NREMT-NRP techniques - NREMT National Registered Paramedic Updated: 2023
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Exam Code: NREMT-NRP NREMT National Registered Paramedic techniques November 2023 by Killexams.com team|
NREMT-NRP NREMT National Registered Paramedic
The NREMT-NRP (National Registered Paramedic) certification exam is designed to assess the knowledge and skills of paramedics in providing advanced medical care in emergency situations. This exam evaluates the candidate's ability to apply critical thinking and clinical judgment in various medical scenarios. The following description provides an overview of the NREMT-NRP certification.
Number of Questions and Time:
The NREMT-NRP exam typically consists of approximately 135-150 questions. The exact number of questions may vary, as the NREMT regularly updates the exam content. Candidates are given 2 hours and 30 minutes (150 minutes) to complete the exam.
To prepare for the NREMT-NRP exam, candidates can undergo comprehensive training programs that cover a wide range of subjects related to advanced paramedic care. These courses provide in-depth knowledge and practical skills required to become proficient in providing advanced medical interventions. The course outline may include the following topics:
1. Advanced Patient Assessment:
- Comprehensive patient assessment techniques
- Advanced airway management and ventilation
- Hemodynamic monitoring and assessment
- Neurological assessment and management
2. Advanced Cardiac Care:
- Advanced cardiac rhythm interpretation
- Defibrillation and cardioversion
- Pharmacological interventions for cardiac emergencies
- Cardiac pacing and external cardiac support
3. Trauma Management:
- Advanced trauma assessment and triage
- Management of traumatic injuries (head, chest, abdominal, musculoskeletal)
- Advanced airway management in trauma patients
- Hemorrhage control and fluid resuscitation
4. Medical Emergencies:
- Management of medical emergencies (respiratory, cardiovascular, neurological, etc.)
- Pharmacological interventions for medical emergencies
- Endocrine and metabolic emergencies
- Environmental emergencies (heatstroke, hypothermia, etc.)
5. Special Populations:
- Pediatrics and neonatal care
- Geriatric care
- Obstetric and gynecological emergencies
- Behavioral and psychiatric emergencies
The NREMT-NRP exam aims to assess the candidate's knowledge and skills in providing advanced paramedic care. The exam objectives include the following:
1. Demonstrate proficiency in advanced patient assessment techniques and critical thinking skills.
2. Apply advanced airway management and ventilation techniques.
3. Perform advanced cardiac care, including rhythm interpretation, defibrillation, and pharmacological interventions.
4. Manage traumatic injuries, including assessment, stabilization, and appropriate interventions.
5. Manage a wide range of medical emergencies using evidence-based practices and pharmacological interventions.
6. Provide specialized care for pediatric, neonatal, geriatric, obstetric, and behavioral health patients.
The NREMT-NRP exam syllabus covers a comprehensive range of subjects related to advanced paramedic care. The syllabus includes the following areas of study:
- Advanced patient assessment and management
- Advanced airway management and ventilation
- Cardiac care and dysrhythmia interpretation
- Trauma assessment and management
- Medical emergencies and pharmacology
- Special populations and specialized care
The NREMT-NRP exam format typically includes multiple-choice questions, scenario-based questions, and skill-based stations. Candidates are required to apply their knowledge and skills to real-world situations and demonstrate competency in providing advanced paramedic care.
|NREMT National Registered Paramedic|
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NREMT National Registered Paramedic
When is a detailed head-to-toe assessment performed?
A. After the primary survey
B. After assessing vitals
C. After a demo history
D. After a wet check
The detailed head-to-toe check should be performed after vitals have been
The radio code that refers to position or location is coded as what?
D. Echo Bravo
To refer to position or location on a radio, 10/20 is used.
ETA is an acronym that stands for:
A. Emergency trust agreement
B. Enabled translation account
C. Estimated time of arrival
D. Enhanced tertiary airway
Estimated time of arrival is commonly shortened to ETA.
The acronym PERL is used to assess what?
A. Pupil dilation
B. Level of consciousness
C. Event history
PERL (pupils equal and reactive to light) assesses the equality and the size of
Which of the following assessments is not required when assessing the neck?
A. Tracheal deviation
B. Jugular vein distension
D. Paradoxical motion
Paradoxical motion occurs in the chest area. It refers to the unequal rise and fall of
What is most essential requirement when assessing a patients breathing with a
A. To listen for a heartbeat
B. To assess bilaterally
C. Check one side of the apex during a pneumothorax
D. Listen for wheezing
Checking the breath sounds bilaterally will tell you whether both lungs are
The acronym DCAP-BTLS is usually used in which of the following
A. The scene survey
B. The wet check
C. The detailed head-to-toe check
D. The demo history
DCAP-BTLP (deformities, contusion, abrasions, punctures, burns, lacerations,
and swelling) is used during a head-to-toe check.
What gland is assessed by a combination of bidigital palpation and circular
A. Pituitary gland
B. Hormone gland
C. Thyroid gland
D. Parotid gland
The thyroid gland is assessed by a combination of bidigital palpation and circular
compression. The assessment is for asymmetry and enlargement of the thyroid
gland. The assessment is done by having the client sit upright and by asking him
or her to swallow.
Which is not a pathogen route of transmission?
Vapor is not a pathogen route of transmission. The routes of transmission are
droplet, vector-borne, indirect, direct, airborne, and fecal-oral. For these routes to
function there must be a source of infectious microorganisms and a susceptible
When questioning a patient, it is important to gather as much information as
possible. What is not a question type?
Indirect is not a question type. When questioning a patient, it is important to
gather as much information as possible. Question types include open-ended,
direct, probing, leading, laundry list, and facilitating. When communicating, avoid
jargon that patients may not understand and confirm at the appointments end that
the patient understands what has been discussed.
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An MD&DI April 1998 Column
Four molding techniques open up a variety of new approaches to the design of medical components.
Plastics injection molding and applications development for medical devices are two areas of technology that perpetually leapfrog one another. The increased functional requirements of molded medical components drive the molding technology advances required to fulfill those needs. In turn, the increased capabilities of the injection molding process facilitate innovations in design, manufacturing, and assembly of new medical devices.
In most cases, past and present, conventional injection molding technology has been sufficient to meet the needs of the applications developed. When conventional molding has fallen short, however, novel improvements and modifications to the process have been devised to provide unique solutions to the increasingly sophisticated demands of medical design engineers. There have been many such improvements, but four in particular stand out. The first, pulsed cooling and induction coil heating, takes the conventional molding process and adds to it a greater degree of process control. For two others, gas-assisted injection molding and multiâlive feed molding, auxiliary equipment is incorporated into the standard machine design. The last technique, multimaterial molding, requires modified molding machines and tooling for optimal success.
PULSED COOLING AND INDUCTION COIL HEATING
This innovative method for controlling mold temperature (Figure 1) overcomes a previously unavoidable drawback in moldcooling methodology. In the conventional molding process, coolant such as water or oil is circulated through the mold continuously while mold temperature is regulated by a controller such as a thermolator or chiller. This type of temperature control maintains a reasonably consistent water-inlet temperature to the mold.
Figure 1. Pulsed cooling and induction coil heating maintains temperature during the injection stroke by closing manifold valves and stopping water flow.When the injection stops, the valves reopen until the steel cools to the desired temperature. Illustration courtesy of Ken A. Kerouac
When plastic is injected into the mold cavity, the mold temperature rises as heat is transferred from the molten plastic to the mold itself. As the molded part cools and solidifies, heat is conveyed out of the system by transfer to the circulating cooling medium and, to a lesser extent, through the mold base to the ambient environment. Cooling continues through mold opening, part ejection, and mold closing, right up until polymer injection on the subsequent shot. This process has unfortunate implications for the polymer. The melt is now being injected into the mold at what is, from a thermal standpoint, the worst possible moment in the cycleâthe point at which the mold is at its coldest temperature. Ideally, coolant should be flowing through the mold only when it is required: from the end of polymer injection to the point where the part is cool enough to be ejected.
The pulsed cooling process is designed to address this problem. A manifold fitted with solenoid-controlled water valves is placed in the supply line between the incoming water source and the mold. The manifold is linked to a controller, which is in turn linked to probes that are inserted into each half of the mold just under the parting line surface. The desired steel temperature (monitored by the probes) is set on the controller. During the injection stroke, the manifold valves are closed, permitting no water flow (and therefore no cooling) to the mold. At the end of injection, a signal is sent to the manifold to open all of the valves and pulse cold water through the system. Once the probes sense that the desired steel temperature is reached, water flow through the mold is again terminated until the next shot.
A unique feature of this system is that with larger, complex molds in which heat transfer from the part will not occur uniformly, more probes may be used in conjunction with manifolds that have a greater number of ports. This will allow for independent zones of control within the mold, so that water flow to areas that are sufficiently cooled will be closed off and diverted to warmer areas of the mold. This degree of control affords the opportunity for better part uniformity and reduced cycle time.
A coinjection molding machine forms parts using two materials (one skin and one core), taking advantage of the benefits of both (Ferromatik Milacron, Cincinnati).
With high-temperature polymers, particularly those that run with hot oil rather than water, the problem is often not losing heat too slowly but too rapidly. A high thermal gradient exists between the hot mold and the ambient air, and the resulting heat transfer may overcool the mold in spite of the benefits of the pulsed water flow. In such cases, the pulsed cooling may be supplemented by, or even replaced by, induction coils inserted into each half of the mold. These coils are also controlled by the unit that regulates the water manifold. Their function is to provide background heating to the mold around its perimeter, thus preventing excessive heat loss and maintaining a better thermal equilibrium within the mold. The drawback to induction coils is that they will only work with ferrous mold materials and therefore are not suited for prototyping efforts with molds made out of aluminum or nonferrous alloys.
Pulsed cooling can be retrofitted to existing molds relatively inexpensively. Because the polymer will fill the cavity under warmer conditions, parts with lower, more uniform molded-in stress can be achieved. This can promote better dimensional stability, including heat-distortion resistance, reduced birefringence in transparent parts, more uniform surface finish, more uniform crystallinity development, and therefore more uniform shrinkage. Studies have also Verified cycle time improvements with some applications of between 10 and 20%.
GAS-ASSISTED INJECTION MOLDING
Although the earliest patents on gas-assisted molding were issued in the mid- to late 1970s, the process has only come into its own over the last five years, after a quiet gestation period in the 1980s. Its latest explosive growth has shown it to be a truly enabling technologyâthings can be achieved with gas-assist that are simply not possible with any other type of molding process.
Gas-assisted molding evolved from a modification of the structural foam process known as gas counterpressure, in which a sealed mold cavity is pressurized with nitrogen before the introduction of the polymer/blowing agent blend. The pressure in the cavity prevents the foaming action of the blowing agent from taking place at the melt front, allowing a smooth skin to be formed at the surface while the cellular structure is created in the core. This process minimizes the surface swirls, splay, and imperfections that often made foamed parts difficult to finish or paint.
Gas-assist, like its parent technology, employs prepressurized nitrogen, but in this case no blowing agent is used in the polymer, and the gas is injected into the interior of the polymer shot, creating a part with a polymer skin that is either entirely hollow or solid with hollow sections, depending on the design (Figure 2). Unlike structural foam, gas-assist produces no cellular structure; the polymer and gas form separate, discrete layers.
Figure 2. Injection, hold, and release sequence for gas-assisted molding of hollow or partially hollow parts. Illustration courtesy of Cinpres, Ltd. (Tamworth, UK).
Suppliers of gas-assist equipment offer a wide choice of hardware and controls, but in all cases the basics of the process are similar. A stand-alone gas-assist unit wired to receive signals from the molding machine draws from a nitrogen source (in most cases either a bottle or a nitrogen generator) and prepares a pressurized charge of nitrogen to be delivered to the mold. As the injection stage of the cycle begins, a signal based on time, pressure, or screw position is sent to the gas unit to trigger gas injection at the appropriate time. Gas may be injected either into the polymer melt through a specially designed molding machine nozzle, which sends the gas through the sprue, runners, and gates before entering the part cavity, or directly into the mold itself through gas nozzles fitted into the mold base.
Once injected into the polymer, the gas bubble finds the path of least resistance, favoring the best combination of high temperature and low pressure. In a properly designed tool run under the proper process conditions, the nitrogen, which is much lower in viscosity than the polymer, remains isolated in the gas channels of the part without bleeding out into any thin-walled areas. The gas channels are those areas that have been thickened to achieve functional utility in the part or to promote better flow of the polymer during filling. Because of the lower viscosity of the gas, the pressure drop across the gas bubble is much lower than across a normal polymer shot. This phenomenon accounts for the ability of gas-assist to provide a higher degree of packing than is possible with the traditional process and to allow the melt to travel longer flow lengths in the mold with fewer gates.
Once the gas has aided the polymer in filling out the cavity, it is held under pressure until the material solidifies, with the gas-hold stage replacing the hold stage in a conventional cycle. The gas is then allowed to vent from the part in order to relieve the internal pressure prior to mold opening. By coring out thick sections with gas, significant cycle time savings can be achieved since there are no thick sections of plastic that require a long time to cool. During the period between the end of gas hold and part ejection, the gas unit is recharged with nitrogen for the next shot.
Gas-assist applications often fall into one of three categories:
With the gas-assist process, thick parts can be molded without cycle time sacrifices and associated issues such as sink marks and voids. Parts cored out with gas will be lighter, with a higher stiffness-to-weight ratio, resulting in material savings and reduced costs. Large parts can be filled more easily, creating parts with less molded-in stress and better dimensional stability. The surface appearance of gas-assist parts is much improved over that of structural foam. Many items produced by gas-assist do not require paint or any other kind of secondary finishing step.
MULTIâLIVE FEED MOLDING
The conventional injection molding process imposes severe limitations on how the polymer melt may be manipulated once it has filled the cavity. Between the end of first-stage injection and final part ejection only two external effects can act on the melt. The first is heat removal through a combination of conduction and convection. The second is the relatively static pack-and-hold pressures applied by the screw. Used to compensate for volumetric shrinkage and to prevent sinks from forming as the part solidifies, these pressures can only be applied until the gate freezes off. The multiâlive feed (MLF) process (Figure 3) employs auxiliary injection molding equipment to achieve dynamic oscillation of the polymer melt within the mold cavity. This oscillation creates a shearing effect on the polymer that prolongs the time the material remains in the molten state and promotes improved orientation and weld line characteristics.
Figure 3. The multiple live feed process, showing (A) out-of-phase oscillation (fill), (B) in-phase oscillation (pack), and (C) holding phase. Illustration courtesy of Eliot M. Grossman (Cinpres-Scorim, Ltd., Tamworth, UK).
Weld lines are molding defects created when multiple polymer flow paths converge in a cavity, such as when melt fronts from different gates meet each other or when flow from a single gate is forced to split and recombine around a pin or other projection in the tool. Weld lines can create appearance problems, since their visibility on the surface may require a costly painting step, or they may be structurally objectionable, since weld lines are inherently weak areas of the parts that can act as stress concentrators and possible failure points in impact or flex situations.
The heart of the MLF process is the head, which mounts to the front of the injection barrel. Within this head, the polymer shot is divided into two independent flow paths and delivered to the mold through two nozzles rather than one, as is done conventionally. A modified sprue bushing with two sprues is required, as is a runner layout that maintains separation of the flow paths.
The head contains hydraulically actuated pistons that act on the melt and provide the oscillation and subsequent pack-and- hold phases employed by the process. Piston motion is controlled by a stand-alone unit synchronized with the injection molding machine by a signal such as first-to-second-stage transfer time or position on each shot.
The MLF process employs three modes of operation:
The MLF unit controls five specific parameters:
The MLF process may eliminate the need to paint parts by reducing the surface weld-line severity to the point where the weld lines are virtually invisible. Whether the surface weld lines are eliminated or not, the internal ones may be altered to a degree that will make the part stronger than it would be with weld lines formed by conventional processes. In fiber-reinforced parts, orientation of the fibers is improved, achieving improved strength in the fiber direction. Filling of thin-wall parts may be facilitated if the oscillation is initiated during polymer fill, creating the shearing effect that may postpone the onset of rapid cooling and solidification that can limit the success of thin-wall molding.
Unlike the other three processes reviewed above, which superimpose auxiliary equipment and some mold modifications onto otherwise standard molding machines, multimaterial molding requires specialized molding equipment in and of itself. A number of different methods fall under the broad umbrella of multimaterial molding: coinjection, overmolding, two-shot molding, and sandwich molding. In all cases, the basic premise of multimaterial molding is to take economical advantage of two or more materials with uniquely different properties by incorporating them into one molded component.
The fundamental equipment requirement for multimaterial molding is to have as many plasticating units (machine barrels) as there are materials to incorporate into the molded part. With some machine designs, multiple barrels are mounted onto the machine base itself; with other systems, the design is more modular, allowing barrels to be added or removed as needed and aligned in different configurations (even vertically) to accommodate more or fewer materials or to adapt for floor space or ceiling height limitations.
Coinjection and Sandwich Molding. These two similar processes (coinjection is sometimes classified as a subset of sandwich molding) form parts with a skin of one material and a core of another, taking advantage of the benefits of both. The critical material requirement in this kind of molding is compatibility. If the two polymers are not compatible, they will not adhere to each other, resulting in delamination at the interface between the two polymer layers and failure of the part.
Figure 4. The coinjection process works by first injecting the skin material (A) then switching to the core material (B). A small amount of skin material can seal the gate to finish the process. Illustration courtesy of Battenfeld of America (West Warwick, RI).
In coinjection molding, two barrels are joined together by a common manifold and nozzle, through which both materials flow before entering the cavity (Figure 4). The nozzle is designed with a shutoff feature that allows only one of the materials to flow through at any given time. To set up the process, the relative percentage of skin to core material is determined, most often by trial and error, and the two barrels are each programmed with the appropriate shot size. On injection, the injection unit with the skin material (often called the A barrel or A side) injects the set amount of polymer. This is followed by the core material in the B barrel which, in a manner similar to gas-assist, penetrates the skin polymer and completes filling of the cavity without breaking through to the skin surface. Since plastics flow in injection molding is laminar, the two materials can be molded in this skin-core configuration without mixing with each other.
Coinjection molding often has a third stage, in which a small amount of skin material completes the injection stage. This is known as an A-B-A injection sequence and accomplishes the task of completely encapsulating the core material, thus protecting it from any weathering, chemicals, or other exposures to which it might be susceptible.
Figure 5. Sandwich molding's multiple plasticating units serve as extruders that allow fixed amounts of material into a single injection unit. Illustration courtesy of Ferromatik Milacron (Cincinnati).
Sandwich molding also results in a skin-core structure, but the mechanics are slightly different (Figure 5). In this process, multiple plasticating units are used only as extruders to feed their percentage of the total shot to a single injection unit. The injection unit itself also accounts for one of the polymer layers. Prior to injection, then, the injection unit has built up a shot consisting of as many layers as there are materials. Again, because of the laminar nature of polymer flow in the injection molding process, these layers do not mix with each other.
Upon injection, the last material fed to the injection unit, which is at the front of the barrel, becomes the skin of the part, and all of the subsequent layers form beneath it, working toward the center, until the last material in, which was that material plasticized by the injection unit itself, becomes the very core. Because all of the injection is done through only one injection unit, there is no opportunity for an A-B-A sequence, as in coinjection; therefore, complete encapsulation of the core is not possible. The core will be exposed at the gate leading into the cavity, which is often not a problem if the gate is on an area of the part that will be hidden or if the material in the core is resistant to the detrimental effects of environmental or chemical exposure.
Coinjection and sandwich molding can provide both economical and functional advantages to a molder. Economically, material costs can be reduced by having the premium or more expensive material only on the outside of the part where it is visible, while the inside may be filled with a less expensive resin. The core of a coinjected part may also be an excellent outlet for regrind generated in production operations. Functionally, parts can combine both structure and utility. A part requiring surface features such as a soft touch, or a 100% color match to eliminate paint, may be molded with a more rigid core material, or even a filled one, to provide a good combination of a soft, pliable surface and high rigidity.
Overmolding. With sandwich or coinjection molding, it may not always be apparent that two materials are being used. Overmolding, or two-shot molding, results in parts in which it is clearly evident that more than one material is being used. In these processes, only part of a product is molded in one material, and that molded piece is manipulated so the second material can be molded around, over, under, or through it to complete the final part. This method is sometimes referred to as in-mold assembly, since the resulting part effectively acts as an assembly of two materials rather than as a layered structure.
Tool design is a critical element for successful overmolding. In some designs, the first component is molded in the first material; then sliding action in the tool creates an additional cavity space that can be filled by the second material to complete the in-mold assembly of the part. The mold cavity also has to be transported, either by mold rotation or mold shuttling, to a position of alignment with the second barrel so it can complete filling of the mold. In other cases, the first molded component has to be physically removed from its cavity and placed in another cavity for molding with the second material. The second molding stage may be another barrel on the same machine, in which the same sort of rotating or shuttling tooling may be employed, or it may be an entirely different mold on an entirely different machine, which saves tooling costs but ties up two machines instead of one.
In most cases, good compatibility of the different materials is required to promote good adhesion and to prevent delamination and part failure. In some cases, however, incompatible materials may be deliberately molded with each other for applications in which relative motion between the two subcomponents is desired. It is possible, for instance, to create a jointed part with a ball molded in one material and a socket molded in a second, incompatible material. The parts can be assembled right in the mold, and since the materials are incompatible, the ball and socket will not adhere, allowing free movement between the components.
The primary benefit of overmolding is savings on assembly costs. Downstream assembly operations may be eliminated, and time and expense are reduced if mechanical fasteners or adhesives do not have to be purchased, installed, or applied. One of the more commercially visible overmolding applications is toothbrushes that have a soft section built into the handle to achieve a better grip. This application would not be practical if it required any kind of mechanical fastener, and human oral contact may limit the kinds of adhesives that may be considered.
An article such as this can only touch upon the many innovations in molding technology that contribute to the success of medical device manufacturing. As unmet needs continue to be identified, new materials in new designs for new applications will continue to be developed. Injection molding technology will continue to keep pace with these developments and provide the manufacturing capabilities necessary to bring these products to life.
Ken A. Kerouac is a specialist with the applied fabrication technology team in the technical service and development (TS&D) department and Peter F. Grelle is a development leader in the automotive technical service and development group at Dow Plastics (Midland, MI).
Copyright Â©1998 Medical Device & Diagnostic Industry
The American Society for Radiation Oncology (ASTRO) updated their guidelines on partial breast irradiation (PBI) for patients with early-stage invasive breast cancer or ductal carcinoma in situ (DCIS).
These new guidelines take into account results from multiple randomized controlled trials that have been published since ASTRO last issued recommendations for PBI in 2017. The trials included more than 10,000 women with about 10 years of follow-up, and, according to ASTRO guideline task force members, demonstrated "oncologic equivalence" between PBI and whole-breast irradiation (WBI) for the treatment of early-stage breast cancer and DCIS.
"For patients with early-stage breast cancer, many are eligible for consideration of partial breast irradiation," Task Force Chair Janice Lyons, MD, of the University Hospitals Seidman Cancer Center in Cleveland, told MedPage Today. "This is a conversation radiation oncologists should have with their patients and they can use the guidelines as a framework on how to have that discussion and how to deliver partial breast irradiation safely."
According to Lyons, one of the key differences in the updated guidelines is that they are "more liberal" regarding the age at which PBI may be appropriate.
The 2017 guidelines recommended that women ages 50 and older be considered "suitable" for PBI outside a clinical trial, while women ages 40 to 49 were included in the "cautionary" group, and those ages 40 and under be included in the "unsuitable" group.
The updated guidelines state that, for patients with early-stage, node-negative invasive breast cancer, PBI is strongly recommended as an alternative to WBI if the patient has favorable clinical features and tumor characteristics, including grade 1 to 2 disease, estrogen receptor (ER)-positive status, age 40 or older, and small tumor size.
PBI is conditionally recommended if the patient has an indication of higher recurrence risk, including grade 3 disease, ER-negative histology, or larger tumor size. It is not recommended for patients with positive lymph nodes, positive surgical margins, or germline BRCA1/2 mutations, or those who are younger than 40, and is conditionally not recommended for patients with less favorable risk features (e.g., lymphovascular invasion or lobular histology), due to the lack of robust data on these patient subsets.
For patients with DCIS, the recommendations align with those for early-stage breast cancer. PBI is strongly recommended as an alternative to WBI for patients with favorable clinical and tumor features outlined in the guideline, conditionally recommended for those with higher-grade disease or larger tumors, and not recommended for patients with positive surgical margins, BRCA mutations, or age less than 40.
"At this point so many randomized controlled trials have been conducted that we were able to really drill down into the subgroups of patients to better define those represented sufficiently enough to strongly recommend partial breast radiation rather than whole breast radiation," said Simona F. Shaitelman, MD, of the University of Texas MD Anderson Cancer Center in Houston, who served as the task force's vice chair.
Shaitelman pointed out that the updated guidelines also dealt with issues related to the delivery of PBI.
Recommended techniques for PBI include 3-D conformal radiation therapy, intensity-modulated radiation therapy, and multi-catheter interstitial brachytherapy, based on studies showing similar long-term rates of ipsilateral breast recurrence compared with WBI.
Single-entry catheter brachytherapy is conditionally recommended, while intraoperative radiation therapy (IORT) techniques, including electron IORT and photon (kV) IORT without WBI, are not recommended unless part of a clinical trial or multi-institutional registry.
The guideline also outlines the optimal dose-fractionation regimens, target volume delineation, and treatment planning parameters for different PBI techniques.
A daily or every-other-day course of PBI is recommended over twice-daily regimens, and the guidelines also pay particular attention to clinical and cosmetic side effects of PBI.
"I think the guidelines highlight how in certain scenarios, partial breast irradiation is actually more favorable than whole-breast irradiation," said Shaitelman. "And that's an important point to highlight to patients in order to Excellerate their overall quality of life if they require radiation as part of their oncologic care."
Lyons reported serving as a board examiner for the American Board of Radiology and consulting for Primum.
Shaitelman reported relationships with Alpha Tau Medical, Artios Pharma, Becton, Dickinson & Co., Elekta, the Emerson Collective Foundation, Exact Sciences, the NIH, and TAE Life Sciences, and serving on the editorial board of the journal Brachytherapy.
Practical Radiation Oncology
Source Reference: Shaitelman SF, et al "Partial breast irradiation for patients with early-stage invasive breast cancer or ductal carcinoma in situ: an ASTRO clinical practice guideline" Pract Radiat Oncol 2023; DOI: 10.1016/j.prro.2023.11.001.
Early Detection and Gender Disparities in COPD
Dr. MeiLan Han
In thisÂ interview, Dr. MeiLan Han, a distinguished pulmonologist and Chief of the Division of Pulmonary and Critical Care at the University of Michigan, shares her profound insights into Chronic Obstructive Pulmonary Disease (COPD).
(MENAFN- GlobeNewsWire - Nasdaq) As the aging population and number of diseases increase, the demand for syringes in Europe is expected to increase.
Wilmington, Delaware, United States, Nov. 17, 2023 (GLOBE NEWSWIRE) -- Transparency Market Research Inc. - The syringes market was worth US$ 4 billion in Europe in 2021. From 2022 to 2031, it is projected to grow at a CAGR of 5.6%. The market for syringes in Europe is estimated to reach US$ 6.9 billion by 2031. COVID-19 has increased global pandemic preparedness. A rapid and effective response to future health crises can be ensured by stockpiling essential medical supplies, such as syringes.
Traditional needle-based injections can be replaced with needle-free injection technologies. For delivery of medication with these systems, jet injectors or microneedles are often used. Infections and needlestick injuries can be reduced with the use of smart syringes. Injection processes can be monitored and controlled with electronic components or retractable needles.
A growing interest in biodegradable and sustainable materials is being expressed in developing syringes and medical devices. Self-administered injections are made easier with autoinjectors. In treating autoimmune diseases, these devices are often used to deliver specific medications. Personalized drug delivery systems have become increasingly important with advances in precision medicine. Enhanced efficacy and reduction in side effects can be achieved by customizing the dosage of medications and delivery methods to the individual patient's characteristics.
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Data tracking and monitoring features are being incorporated into some syringe technologies. Patients and healthcare providers can benefit from better medication management by integrating digital health platforms. The use of nanotechnology in drug delivery mechanisms is being explored. In addition to enhancing targeted delivery, nano-sized particles and structures may lead to improved therapeutic outcomes.
3D printing technology can create more customizable and intricate designs for medical devices, including syringes. Developing solutions tailored to patients can be made easier this way.
Key Findings of Market Report
Global Syringes Market: Growth Drivers
COVID-19 and other infectious diseases have caused the demand for syringes to rise. A growing number of vaccine campaigns and routine immunizations are boosting the syringe market. Chronic diseases like diabetes are becoming more prevalent around the world. As a result, syringes have become less common for administering injectable medications, including insulin.
Enhanced needlestick safety, easy-to-use designs, and drug-compatible materials can drive syringe technology innovation. As a result of these advancements, drug delivery has become safer and more efficient. Medical devices, including syringes, are in high demand as global healthcare expenditures rise. Investments in healthcare infrastructure are increasing in developing countries, contributing to market growth.
Syringe demand is largely driven by an expanding market for biologics and biosimilars. In addition to treating cancer and autoimmune diseases, these products are also used in other conditions. The quality and safety of medical devices, including syringes, is strictly regulated. Industry innovation and quality improvements can be driven by compliance with these regulations.
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Global Syringes Market: Regional Landscape
Global Syringes Market: Key Players
Syringes are a consolidated market, with a few major vendors controlling most of the market. Research & development is a top priority for key firms, especially those involved in environmental protection. Mergers & acquisitions and expanding product portfolios are key strategies key players adopt.
Global Syringes Market: Segmentation
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Lymphatic drainage massage is a form of gentle massage that encourages the drainage of lymph nodes and the movement of lymph fluids around the body. It can help relieve symptoms of lymphedema.
The fluid in the lymphatic system helps remove waste and toxins from body tissues. Some health conditions can cause lymph fluid to build up.
In this article, we discuss the benefits of lymphatic massage, who may find it useful, and how a person can prepare for and perform it at home.
Lymphatic massage, sometimes called manual lymphatic drainage, is a specialized type of medical massage. It can help treat lymphedema, in which lymphatic fluid collects in certain areas of the body because it cannot drain away effectively.
Lymphatic massage aims to Excellerate the flow of lymph fluid, which should reduce swelling. Massaging an area without swelling will make space for fluid to flow to those parts from more congested areas.
There are two types of lymphatic drainage:
Anyone planning on learning simple lymphatic drainage should learn how to do it from a specialist. It is essential to know which area to massage and how much pressure to use.
Who can benefit?
Lymphatic massages can benefit people who have a buildup of lymphatic fluid. This may occur due to:
Lymphatic buildup affects around 1 in 5 females after treatment for breast cancer.
According to a 2021 review, manual lymph drainage may also Excellerate the quality of life in people with fibromyalgia.
However, this type of massage may not be suitable or safe for some people, for example, if they have cellulitis or a heart condition. People should speak with a doctor before using lymphatic massage.
Trained professionals, including physical therapists or massage therapists with a certified manual lymphatic drainage therapist certificate, can provide lymphatic massage and teach an individual basic drainage techniques to use at home.
People can perform most of these exercises either standing, sitting, or lying down, as long as they are comfortable.
Keep the following tips in mind during a lymphatic massage:
The following preparation methods will stimulate the lymphatic system and prepare the lymph nodes to bring in more fluid before a lymphatic massage.
1. Lymphatic breathing
Deep breathing acts like a pump that helps move fluid through the vessels and lymph nodes. Follow the steps below:
2. Prepare the front of the neck
The United Kingdomâs National Health Service (NHS) recommends the following steps to prepare the front and sides of the neck:
4. Prepare the back of the neck
The following steps can prepare the back of the neck:
5. Prepare under the arms
Prepare the lymph nodes under the arms to help them accept lymph fluid from other areas of the body. Do not perform this movement on areas that doctors have treated for cancer. Follow these steps:
6. Prepare behind the knees
Upper body massage techniques
Use the following techniques to help drain lymph fluid from the chest, shoulder, and upper arm.
To massage the chest:
To massage the shoulder:
To massage the upper arm:
To massage the full arm:
To massage the fingers:
Lower body massage techniques
Start the massage at the top of the leg and work down toward the foot. Use a pillow or stool for support.
To massage the upper leg:
To massage the lower leg:
To massage the toes, use the thumb and index finger and stroke the skin from the tip of each toe toward the base.
It is vital to always end the massage by drinking extra fluids.
People who use lymphatic drainage massages may notice that their swelling reduces. At the very least, swelling should not worsen. People can attend regular checks with a doctor to monitor whether this procedure works for them.
People with lymphedema should continue using compression socks or sleeves to prevent swelling.
People can also boost their lymphatic system function and help remove more waste from the body using the following methods:
The lymphatic system plays a key role in the bodyâs immune defenses. Lymphatic fluid flows through lymph vessels, which connect lymph nodes. As it passes through the lymph nodes, white blood cells trap and destroy harmful particles, such as bacteria.
Like blood in the circulatory system, lymphatic fluid is always moving. If it stops, swelling can occur due to fluid build-ups, often in the arms or legs. Health experts call this lymphedema.
Lymphatic massage usually forms part of a treatment program that health experts call decongestive lymphatic therapy (DLT). This treatment plan may also include skin care, exercise, and compression garments.
Together, these can Excellerate circulation throughout the lymphatic system and help manage symptoms of lymphedema.
Here are some questions people often ask about lymphatic drainage.
What does a lymphatic drainage massage do?
It aims to reduce swelling by relieving the buildup of lymph fluid in people with lymphedema or other conditions.
What are the symptoms of a poor lymphatic system?
Symptoms of lymphedema may include:
How often should someone get a lymphatic drainage massage?
DLT, which includes lymphatic massage, may involve daily treatment over several weeks before becoming less frequent.
However, the frequency of massage may depend on a personâs needs and the severity of their symptoms.
How can I drain my lymphatic system at home?
Simple lymphatic drainage techniques are suitable for home use, as described in this article. People should use light pressure during the massage and avoid any areas with swelling.
How painful is lymphatic massage?
It should not be painful. The fingers will stroke the skin very lightly. However, if there is pain or redness, a person should stop the massage and consult a specialist for guidance.
A person can use lymphatic drainage massage techniques to help reduce swelling and Excellerate circulation. An effectively functioning lymphatic system is essential for overall health.
People who think that they could benefit from a lymphatic drainage massage should speak with a physical therapist, preferably one who specializes in treating lymphedema.
Healthcare professionals can perform the massage or teach someone massage techniques to use at home.
Twenty years ago, Shoaib Akhtar became the first person recorded to bowl at 100mph (161km per hour) during the 2003 One-Day International Men's World Cup match for Pakistan against England. There was an expectation afterwards that this feat would become a regular occurrence.
As humans have continued to run faster, throw further and jump higher, it was believed that this milestone would be a stepping stone consigned to history similar to Roger Bannister breaking the four-minute mile. It was thought it might also act as a catalyst for serious worldwide improvement in fast bowling.
However, despite continuing improvement in the athletic ability of fast bowlers, the magical three-figure barrier has only been surpassed since by Brett Lee and Shaun Taitâand not for over ten years.
Has cricket fast bowling's top speed stalled? During the current 2023 One-Day International Men's World Cup being hosted in India, only a handful of bowlers have produced speeds over 90mph (145km per hour), with the fastest being around 95mph (153 km per hour).
The performance of cricket fast bowlers almost entirely depends on two factors. The first is the amount of momentum developed in the run-up and maintained before the front foot contacting the floor. The second is the technique employed to generate and transfer momentum within the body during the bowling phase between the front foot contacting the floor and the release of the ball from the bowler's hand.
Previous research has highlighted that the fastest elite male bowlers generate more momentum in their run-up, adopting a movement strategy that aims to maintain and transfer this momentum into the throw instead of generating additional momentum from their muscles.
Testing the limits
To investigate the limits of fast bowling performance, a world-leading predictive musculoskeletal computer simulation model of ten elite male fast bowlers (essentially a virtual clone of each bowler) was developed. It then optimized their technique to maximize the release speed of the ball.
Significantly, none of these bowlers were predicted by the computer model to break the 100mph barrier.
To understand why the top speed has stalled, it is important to consider how all the factors influencing human movement patterns affect the technique of fast bowlers.
The behavior of all our movement patterns is shaped by three types of constraint. The first is organismic: these are constraints on the individual, such as their size, strength and range of motion. The second factor shaping movement patterns is the environment the individual interacts with, including the atmosphere, temperature, equipment and surfaces. The third shaping factor is the task, which involves constraints such as the goal of the activity, the rules and the intensity.
Our previous experiences of the movementâwhat we have seen, what we have been told and our previous performance of the movementâalso affect individual technique in fast bowling.
The innate physiology of the fast bowler, an organismic constraint, provides the only potential area for development in fast bowling. The other constraints, such as environment and task, which often lead to scientific and technological development associated with improvements in other sports, are extremely limited in fast bowling. This is due to the lack of equipment and the simplicity of the activity.
The physiological aspect often considered to be associated with improvements in fast bowling performance is an increase in muscular strength, power and endurance. However, there's a unique cricket bowling "task" constraint which requires bowlers to maintain a straight arm during the bowling phase. This significantly reduces the time available to complete the throwing movement.
Elite males complete the bowling phase in approximately 100 milliseconds. This is similar to the time required to explosively activate a single muscle. This limits the ability of bowlers to develop additional momentum using their muscles in the bowling phase and neutralizes the effect of strength increases on ball speed.
This explains why maximizing momentum generated during the run-up is preferred over generating muscular momentum during the bowling phase. It also explains why fast bowling top speeds have not increased despite latest advances in fast bowlers' athletic abilities.
Interestingly, research on women fast bowlers has highlighted that bowlers who generate less momentum during the run-up and therefore have more time available to generate additional muscular momentum, adopt a movement pattern more akin to throwing. In this approach, the momentum generated in the run-up is added to via the use of large rotational torso muscles within the bowling phase.
Improvements to the performance of the large rotational torso muscles in men and women could possibly Excellerate the generation of muscular momentum. But this approach is considered a sub-optimal technique by the research that's been carried out on fast bowling.
A potential mechanism to increase the time available to develop more momentum from muscles would be to increase the range of motion that joints move through during the bowling phase.
Recent research has highlighted that, on average, elite fast bowlers with an increased range of motion in the hip and shoulder had greater ball release speeds. It was also suggested that the bowlers' techniques were probably influenced by their range of motion during their early learning years.
In addition, elbow hyperextensionâwhere the joint travels beyond a straight positionâhas been shown to increase the speed of ball release by up to 5% during the bowling phase. A common misconception, however, is that taller bowlers will bowl faster due to the benefit associated with increased limb length.
Unfortunately, as limbs get longer, they get more difficult to rotate. As muscular strength does not scale equally with limb length this becomes a disadvantage. Thus, an optimal height for fast bowlers probably exists, though we don't know what it is.
Organismic factors linked with increased ball speed such as body shape, size and hypermobility are largely genetic. Since human evolution is extremely slow, advances in ball release speed are likely to follow at a similar pace.
The 100mph barrier, therefore, should be viewed more as a mountain that requires a once-every-generation bowler to scale rather than a dam in a river. The potential of this peak to grow is limited by the constraints of the task and by our innate physiology.
Citation: The best techniques for being a cricket fast bowler, according to science (2023, November 2) retrieved 17 November 2023 from https://medicalxpress.com/news/2023-11-techniques-cricket-fast-bowler-science.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
When an algorithm-driven microscopy technique developed in 2021 (and able to run on a fraction of the images earlier techniques required) isn't fast enough, what do you do?
Dive DEEPer, and square it. At least, that was the solution used by Dushan Wadduwage, John Harvard Distinguished Science Fellow at the FAS Center for Advanced Imaging.
Scientists have worked for decades to image the depths of a living brain. They first tried fluorescence microscopy, a century-old technique that relies on fluorescent molecules and light. However, the wavelengths weren't long enough and they scattered before they reached an appreciable distance.
The invention of two-photon microscopy in 1990 brought longer wavelengths of light shine onto the tissue, causing fluorescent molecules to absorb not one but two photons. The longer wavelengths used to excite the molecules scattered less and could penetrate farther.
But two-photon microscopy can typically only excite one point on the tissue at a time, which makes for a long process requiring many measurements. A faster way to image would be to illuminate multiple points at once using a wider field of view but this, too, had its drawbacks.
"If you excite multiple points at the same time, then you can't resolve them," Wadduwage said. "When it comes out, all the light is scattered, and you don't know where it comes from."
To overcome this difficulty, Wadduwage's group began using a special type of microscopy, described in Science Advances in 2021. The team excited multiple points on the tissue in a wide-field mode, using different pre-encoded excitation patterns. This techniqueâcalled De-scattering with Excitation Patterning, or DEEPâworks with the help of a computational algorithm.
"The idea is that we use multiple excitation codes, or multiple patterns to excite, and we detect multiple images," Wadduwage said. "We can then use the information about the excitation patterns and the detected images and computationally reconstruct a clean image."
The results are comparable in quality to images produced by point-scanning two-photon microscopy. Yet they can be produced with just hundreds of images, rather than to the hundreds of thousands typically needed for point-scanning. With the new technique, Wadduwage's group was able to look as far as 300 microns deep into live mouse brains.
Still not good enough. Wadduwage wondered: Could DEEP produce a clear image with only tens of images?
In a latest paper published in Light: Science and Applications, he turned to machine learning to make the imaging technique even faster. He and his co-authors used AI to train a neural network-driven algorithm on multiple sets of images, eventually teaching it to reconstruct a perfectly resolved image with only 32 scattered images (rather than the 256 reported in their first paper). They named the new method DEEP-squared: Deep learning powered de-scattering with excitation patterning.
The team took images produced by typical two-photon point-scanning microscopy, providing what Wadduwage called the "ground-truth." The DEEP microscope then used physics to make a computational model of the image formation process and put it to work simulating scattered input images. These trained their DEEP-squared AI model. Once AI produced reconstructed images that resembled Wadduwage's ground-truth reference, the researchers used it to capture new images of blood vessels in a mouse brain.
"It is like a step-by-step process," Wadduwage said. "In the first paper we worked on the optics side and reached a good working state, and in the second paper we worked on the algorithm side and tried to push the boundary all the way and understand the limits. We now have a better understanding that this is probably the best we can do with the current data we acquire."
Still, Wadduwage has more ideas for boosting the capabilities of DEEP-squared, including improving instrument design to acquire data faster. He said DEEP-squared exemplifies cross-disciplinary cooperation, as will any future innovations on the technology.
"Biologists who did the animal experiments, physicists who built the optics, and computer scientists who developed the algorithms all came together to build one solution," he said.
More information: Navodini Wijethilake et al, DEEP-squared: deep learning powered De-scattering with Excitation Patterning, Light: Science & Applications (2023). DOI: 10.1038/s41377-023-01248-6
Citation: Machine learning techniques give scientists faster returns of high-quality organ images (2023, October 17) retrieved 17 November 2023 from https://medicalxpress.com/news/2023-10-machine-techniques-scientists-faster-high-quality.html
This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.
An MD&DI Â January 1998 Column
Choosing the right thermal control element helps ensure accurate functioning of complex electronic, imaging, and processing systems.
Equipment engineers seeking to develop faster and more accurate medical and laboratory products are beginning to recognize the importance of proper thermal management. The speed or accuracy of sensitive electronic devices such as microprocessors and lasers can be affected by thermal conditions, and cooling generally has a positive effect on equipment reliability. Chemical reaction rates are proportional to temperature, and the working time or shelf life of a biological demo or laboratory reagent can be increased by keeping the substance at an optimal temperature. Instruments such as DNA cyclers, tunable laser diodes, and thermal-stress analyzers all require a capacity for cycling an object or demo through a range of temperatures with speed and precision.
Heat sinks can be used with or without fans and offer considerable installation flexibility, but they cannot cool components below ambient temperature. Photo courtesy of Melcor Corp. (Trenton, NJ)
There are many different tools and methods for transferring heat. Which method is best depends on the temperatures and tolerances of the application. Simpler devices might function well enough with passive cooling elements such as heat sinks, while devices that operate in more demanding environments might require an active cooling method such as a compressor-based or thermoelectric system. A fan, for example, can be used to remove the heat generated inside an electronics cabinet. If the cabinet is sealed, a heat sink or heat pipe is needed. If the cabinet's temperature must be controlled, a heat pump or air conditioner is indicated. The best design will be determined by system needs and limitations. System needs would address the amount of heat to be added or removed to achieve the required temperature. Limitations might involve space, cost, allowable vibration, and available power. Once these factors are defined, the thermal engineering choices become apparent. The following is an overview of the thermal management technologies readily available to the engineer, listed from the simplest to the most sophisticated.
FANS AND BLOWERS
Fans operate by passing air over a hot component, absorbing the component's heat. Overall cooling effectiveness is determined by the air's flow rate and temperature together with the component's size and output. Typically, fans and fan trays are used in cabinets for bulk cooling of electronics. Fans and blowers are relatively inexpensive and provide a high measure of flexibility in installation. On the other hand, the constant exchange of air raises the potential for contamination from dust and moisture. Moreover, fans and blowers can prove ineffective for high-power devices and cannot cool an object at or below ambient temperature.
Generally, heat sinks are made from aluminum because of the metal's relatively high thermal conductivity and low cost. They are either extruded, stamped, bonded, cast, or machined to achieve a shape that will maximize surface area, facilitating the absorption of heat by the surrounding cooler air. Most have a fin or pin design. When used with fans (forced convection), heat sinks can dissipate large amounts of heat while keeping the targeted components at 10Â°â15Â°C above ambient temperature. Heat sinks without fans (free convection) result in a higher component temperature because of the decreased impingement of air. Like fans, heat sinks are inexpensive and offer installation flexibility but cannot cool components at or below ambient temperature. Also, heat sinks do not permit temperature control.
Thermoelectric coolers made from semiconductor pairs between ceramic plates (Melcor Corp., Trenton, NJ).
LIQUID COLD PLATES
Liquid cold plates are typically made from copper, aluminum, or aluminum-clad copper tubing. Heat is absorbed by a liquid pumped through the plate, which is attached directly to the object being cooled. In an open-loop system, the liquid (usually tap water) runs through the plate and out through a drain. In a closed-loop system, a pump recirculates the liquid through a heat exchanger or radiator. Liquid cold plates are characterized by a small size (at point of attachment), and they offer effective heat dissipation. The devices are limited by the fact that they cannot cool below ambient (liquid) temperature and permit no temperature control. The potential for leakage is also a concern, and the availability of liquid sources can sometimes pose a problem.
The best design will be determined by system needs, such as the amount of heat to be removed, and limitations, such as space, cost, power, and permissible vibration.
A heat pipe is a sealed vessel that transfers heat by the evaporation and condensation of an internal working fluid. Ammonia, water, acetone, or methanol are typically used, although special fluids are used for cryogenic and high-temperature applications. As heat is absorbed at the evaporator, the working fluid is vaporized, creating a pressure gradient within the heat pipe. The vapor is forced to flow to the cooler end of the pipe, where it condenses, giving up its latent heat to the ambient environment. The condensed working fluid returns to the evaporator via gravity or capillary action within the wick structure. Because heat pipes exploit the latent heat effects of the working fluid, they can be designed to keep a component near ambient conditions. Though they are most effective when the condensed fluid is working with gravity, heat pipes can work in any orientation. Using forced air at the condenser allows for larger amounts of heat dissipation. Heat pumps are typically small and highly reliable, but they can't cool objects below ambient temperature and do not permit temperature control.
Compressor-based cooling systems, found in commercial refrigerators and air conditioners, contain three fundamental parts: an evaporator, a compressor, and a condenser. In the evaporator, pressurized refrigerant is allowed to expand, boil, and evaporate, absorbing heat as it changes from a liquid to a gas. The compressor acts as the refrigerant pump and recompresses the gas to a liquid. The condenser expels the heat absorbed (along with the heat produced during compression) into the ambient environment. Compressor-based refrigeration is effective for large heat loads (300 W or more) and can cool components far below ambient temperature. The technique also allows users to control temperature. These refrigerators must be used in their designed orientation, which limits installation flexibility. Maintenance and reliability are also compromised by moving parts. Compressor-based systems also tend to be bulky and noisy.
Thermoelectric coolers (TECs) are solid-state heat pumps made from semiconductor materials. They have no moving parts but comprise a series of p-type and n-type semiconductor pairs or junctions sandwiched between ceramic plates. Heat is absorbed by electrons at the cold junction as they pass from a low energy level in a p-type element to a higher energy level in an n-type element. At the hot junction, energy is expelled to a heat sink as the electrons move from the high-energy n-type element to a low-energy p-type element. A dc power supply provides the energy to move the electrons through the system. A typical TEC will contain up to 127 junctions and can pump as much as 120 W of heat. The amount of heat pumped is proportional to the amount of current flowing through the TEC; therefore, tight temperature control (<0.01Â°C) is possible. By reversing the current, TECs can function as heaters, which can be useful in controlling an object in changing ambient environments or in cycling at different temperatures. Sizes range from 2 to 62 mm, and multiple TECs can be used for greater cooling. Because of the relatively large amount of heat being pumped over a small area, TECs require a heat sink to dissipate the heat into the ambient environment. The modular units can be used in any orientation and are compatible with heat sinks, cold plates, and heat pipes. On the down side, TECs require a dc power source and are more expensive than passive components.
When mounting a cooling device to a component or assembling a cooling system, designers must select a thermal bonding material that will allow heat to flow out of the device with minimal resistance. Designers should take into account mechanical stresses at the interfaces caused by differing material coefficients of thermal expansion. The idea is to eliminate any air pockets between the two surfaces.
The most common interface material is thermal grease, typically made from zinc oxide in a silicon or petroleum base. There are also pastes available with thermal conductors such as aluminum oxide and aluminum nitride. Pads and foils are less messy to apply and can be cut to match the component footprint. Some pads are available with adhesive surfaces to allow permanent attachment. Aluminum oxide and aluminum nitride are used in thermal pads, as are sheets made from graphite, indium, and aluminum.
Thermal epoxies create rigid, permanent bonds. They are typically supplied as two-part systems comprising a hardener and a resin filled with silver, aluminum, aluminum oxide, or aluminum nitride. Because they are permanent, epoxies should be used only in areas that will not require future disassembly. Rigid bonds can also be achieved using solder. Eutectic and noneutectic formulations are available for use in a wide temperature range. Soldered surfaces offer a good rigid thermal joint and can be disassembled by simply reflowing the solder. As with all rigid joints, the effects of differing thermal expansions should be considered.
High-performance electronics, sensitive imaging equipment, and sample-processing systems all require proper thermal control to ensure accuracy and functionality. Design engineers need to identify temperature-sensitive components in order to create an integrated system with parts that are both compatible and economical. They should do this early in the design process; the sooner thermal limitations are identified, the more flexibility the engineer has in choosing from the available options. In the final analysis, retrofitting thermal products is usually not as effective and economical as generating a solid thermal design from day one.
Robert Smythe is vice president of sales and marketing at Melcor Corp. (Trenton, NJ).
Copyright Â©1998 Medical Device & Diagnostic Industry
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