Temperature Control Unit Research Articles

Treatment of Severe Hypothermia With Intravascular Temperature Modulation

Treatment of Severe Hypothermia With Intravascular Temperature Modulation

A Solid Trap and Thermal Desorption System with Application to a Medical Electronic Nose.

In this paper, a solid trap/thermal desorption-based odorant gas condensation system has been designed and implemented for measuring low concentration odorant gas. The technique was successfully applied to a medical electronic nose system. The developed system consists of a flow control unit, a temperature control unit and a sorbent tube. The theoretical analysis and experimental results indicate that gas condensation, together with the medical electronic nose system can significantly reduce the detection limit of the nose system and increase the system's ability to distinguish low concentration gas samples. In addition, the integrated system can remove the influence of background components and fluctuation of operational environment. Even with strong disturbances such as water vapour and ethanol gas, the developed system can classify the test samples accurately.

A containerless levitation setup for liquid processing in a superconducting magnet

Containerless processing of materials is considered beneficial for obtaining high quality products due to the elimination of the detrimental effects coming from the contact with container walls. Many containerless processing methods are realized by levitation techniques. This paper describes a containerless levitation setup that utilized the magnetization force generated in a gradient magnetic field. It comprises a levitation unit, a temperature control unit, and a real-time observation unit. Known volume of liquid diamagnetic samples can be levitated in the levitation chamber, the temperature of which is controlled using the temperature control unit. The evolution of the levitated sample is observed in real time using the observation unit. With this setup, containerless processing of liquid such as crystal growth from solution can be realized in a well-controlled manner. Since the levitation is achieved using a superconducting magnet, experiments requiring long duration time such as protein crystallization and simulation of space environment for living system can be easily succeeded.

Study on Microstructure-Processing Relationship of a Semisolid Rheocasting A357 Aluminum Alloy

An improved and self-developed semisolid preparing and rheomoulding device — rotating barrel rheomoulding machine (RBRM) for light alloys in laboratory is introduced in this paper. It mainly consists of a melting furnace, a shearing system with two relative-rotating conical barrels, a central temperature control unit, gas protection system and a die-casting system. Microstructure-processing relationship of A357 aluminum alloy obtained by the RBRM process is investigated by different intensity of turbulence and different shear rate. The experimental results show that the improved RBRM is capable of eliminating coarse dendrites, and producing small and spherical solid particles uniformly distributed in a eutectic matrix. In addition, the process can eliminate entrapped gas and reduce fine shrinkage pores in the specimens as well. Compared with the original self-developed device in our laboratory, the improved equipment has the following advantages: accurate control of stirring temperature; small volume and convenient manipulation; fine and spherical solid particles, chemical and microstructural uniformity throughout the specimens and so on.

Compact optical cell system for vacuum ultraviolet absorption and circular dichroism spectroscopy and its application to aqueous solution sample

We have designed a compact optical cell for studying the absorption and circular dichroism (CD) of a solution sample in the vacuum ultraviolet (VUV) region using a temperature control unit. The cell size was 34 mm in diameter and 14 mm in length. Such compactness was obtained by coating the VUV scintillator onto the outside of the back window. Because this scintillator converts the transmitted VUV light to visible light, the outside of this cell is operated under atmospheric pressure. The temperature of the sample solution was maintained in the range of 5 degrees C to 80 degrees C using a temperature control unit with a Peltier thermoelectric element. Changes in the sample temperature were observed by monitoring the absorption intensity of water. Through the study of VUV-CD spectra of ammonium camphor-10-sulfonate aqueous solutions and the transmitted spectrum of an empty cell, it was concluded that this cell unit has sufficient performance for use in VUV spectroscopy.

BIM and tBID Are Not Mechanistically Equivalent When Assisting BAX to Permeabilize Bilayer Membranes

BIM and tBID are two BCL-2 homology 3 (BH3)-only proteins with a particularly strong capacity to trigger BAX-driven mitochondrial outer membrane permeabilization, a crucial event in mammalian apoptosis. However, the means whereby BIM and tBID fulfill this task is controversial. Here, we used a reconstituted liposomal system bearing physiological relevance to explore systematically how the BAX-permeabilizing function is influenced by interactions of BIM/BID-derived proteins and BH3 motifs with multidomain BCL-2 family members and with membrane lipids. We found that nanomolar dosing of BIM proteins sufficed to reverse completely the inhibition of BAX permeabilizing activity exerted by all antiapoptotic proteins tested (BCL-2, BCL-X(L), BCL-W, MCL-1, and A1). This effect was reproducible by a peptide representing the BH3 motif of BIM, whereas an equivalent BID BH3 peptide was less potent and more selective, reversing antiapoptotic inhibition. On the other hand, in the absence of BCL-2-type proteins, BIM proteins and the BIM BH3 peptide were inefficient, directly triggering the BAX-permeabilizing function. In contrast, tBID alone potently assisted BAX to permeabilize membranes at least in part by producing a structural distortion in the lipid bilayer via BH3-independent interaction of tBID with cardiolipin. Together, these results support the notion that BIM and tBID follow different strategies to trigger BAX-driven mitochondrial outer membrane permeabilization with strong potency.

Study on Unusual Pattern Bridge and Its Mechanism

We found unusual pattern bridge after patterning. We traced all possible sources not only materials used at photo mask step but also air bone contaminants. Finally, we found that wafers were contaminated from temperature control unit (TCU) for cooling lens. However, it is a question which one is directly related among motor oil and cooling gas used in TCU. Polyakyleneglycol is the main component of TCU motor oil and chilling gas is 1,1,1,2-tetrafluoroethane (TFE). TFE can be changed into mist when it meets with H2O or other components in the air. They can have an effect on photoresist pattern. Finally, we came to the conclusion that splashed motor oil is the origin of pattern bridging between the two. We solved this bridge issue by introducing acryl wall around TCU.

Dimerization of Hsp90 Is Required for in Vivo Function

Heat shock protein 90 (Hsp90) plays a central role in signal transduction and has emerged as a promising target for anti-cancer therapeutics, but its molecular mechanism is poorly understood. At physiological concentration, Hsp90 predominantly forms dimers, but the function of full-length monomers in cells is not clear. Hsp90 contains three domains: the N-terminal and middle domains contribute directly to ATP binding and hydrolysis and the C domain mediates dimerization. To study the function of Hsp90 monomers, we used a single-chain strategy that duplicated the C-terminal dimerization domain. This novel monomerization strategy had the dual effect of stabilizing the C domain to denaturation and hindering intermolecular association of the ATPase domain. The resulting construct was predominantly monomeric at physiological concentration and did not function to support yeast viability as the sole Hsp90. The monomeric construct was also defective at ATP hydrolysis and the activation of a kinase and steroid receptor substrate in yeast cells. The ability to support yeast growth was rescued by the addition of a coiled-coil dimerization domain, indicating that the parental single-chain construct is functionally defective because it is monomeric.

Role of the Asymmetry of the Homodimeric b2 Stator Stalk in the Interaction with the F1 Sector of Escherichia coli ATP Synthase

The b subunit dimer in the peripheral stator stalk of Escherichia coli ATP synthase is essential for enzyme assembly and the rotational catalytic mechanism. Recent protein chemical evidence revealed the dimerization domain of b to contain a novel two-stranded right-handed coiled coil with offset helices. Here, the existence of this structure in more complete constructs of b containing the C-terminal domain, and therefore capable of binding to the peripheral F1-ATPase, was supported by the more efficient formation of intersubunit disulfide bonds between cysteine residues that are proximal only in the offset arrangement and by the greater thermal stabilities of cross-linked heterodimers trapped in the offset configuration as opposed to homodimers with the helices trapped in-register. F1-ATPase binding analyses revealed the offset heterodimers to bind F1 more tightly than in-register homodimers. Mutations near the C terminus of b were incorporated specifically into either the N-terminally or the C-terminally shifted polypeptide, bN or bC, respectively, to determine the contribution of each position to F1 binding. Deletion of the last four residues of bN substantially weakened F1 binding, whereas the effect of the deletion in bC was modest. Similarly, benzophenone maleimide introduced at the C terminus of bN, but not bC, mediated cross-linking to the delta subunit of F1. These results imply that the polypeptide in the bN position is more important for F1 binding than the one in the bC position and illustrate the significance of the asymmetry of the b dimer in the enzyme.

Engineered Sarafotoxins as Tissue Inhibitor of Metalloproteinases-like Matrix Metalloproteinase Inhibitors

The sarafotoxins and endothelins are approximately 25-residue peptides that spontaneously fold into a defined tertiary structure with specific pairing of four cysteines into two disulfide bonds. Their structures show an interesting topological similarity to the core of the metalloproteinase interaction sites of the tissue inhibitors of metalloproteinases. Previous work indicates that sarafotoxins and endothelins can be engineered to eliminate or greatly reduce their vasopressive action and that their structural framework can withstand multiple sequence changes. When sarafotoxin 6b, which possesses modest matrix metalloproteinase inhibitory activity, was C-terminally truncated to remove its toxic vasopressive activity, the metalloproteinase inhibitory activity was essentially abolished. However, further changes, based on the sequences of peptides selected from libraries of sarafotoxin variants or suggested by analogy with tissue inhibitors of metalloproteinases, progressively enhanced the matrix metalloproteinase inhibitory activity. Peptide variants with multiple substitutions folded correctly and formed native disulfide bonds. Improvements in matrix metalloproteinase affinity have generated a peptide with micromolar K(i) values for matrix metalloproteinase-1 and -9 that are selective inhibitors of different metalloproteinases. Characterization of its solution structure indicates a close similarity to sarafotoxin but with a more extended C-terminal helix. The effects of N-acetylation and other changes, as well as docking studies, support the hypothesis that the engineered sarafotoxins bind to matrix metalloproteinases in a manner analogous to the tissue inhibitors of metalloproteinases.

Ralstonia pickettiiBacteremia Associated With Pediatric Extracorporeal Membrane Oxygenation Therapy in a Canadian Hospital

We describe 2 pediatric patients with Ralstonia pickettii bacteremia associated with extracorporeal membrane oxygenation (ECMO) therapy. Investigation revealed a common environmental source--the ECMO temperature-control units. We created guidelines for disinfecting these units that do not void the manufacturer's warranty and have prevented additional cases of bacteremia due to this organism.

Microchip‐based capillary electrophoresis for determination of lactate dehydrogenase isoenzymes

This article describes a novel microchip-based capillary electrophoresis and oncolumn enzymatic reaction analysis protocol for lactate dehydrogenase (LDH) isoenzymes with a home-made xenon lamp-induced fluorescence detection system. A microchip integrated with a temperature-control unit is designed and fabricated for low-temperature electrophoretic separation of LDH isoenzymes, optimal enzyme reaction temperature control, and product detection. A four-step operation and temperature control are employed for the determination of LDH activity by on-chip monitoring of the amount of incubation product of NADH during the fixed incubation period and at a fixed temperature. Experiments on the determination of LDH standard sample and serum LDH isoenzymes from a healthy adult donor are carried out. The results are comparable with those obtained by conventional CE. Shorter analysis times and a more stable and lower background baseline can be achieved. The efficient separation of different LDH forms indicates the potential of microfluidic devices for isoenzyme assay.

A Digital CMOS Architecture for a Micro-Hotplate Array

A monolithic gas sensor array fabricated in industrial CMOS technology combined with post-CMOS micromachining is presented. The device comprises an array of three metal-oxide-coated micro-hotplates with integrated MOS transistor heaters and the needed driving and signal-conditioning circuitry. Three digital PID controllers enable individual temperature regulation for each hotplate. The operating temperature of the SnO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> metal-oxide sensors may amount up to 350degC. A serial interface and the temperature control units have been implemented digitally. Emphasis was put on designing a modular system with the required analog circuitry reduced to a minimum. With its small overall size of 5.5times4.5<!-- Character "\" changed to \ -->\ mm2, its digital interface and its good hotplate thermal efficiency of 6degC/mW, the system represents a significant development on the way to low-cost mobile gas sensor systems. The limit of detection at constant temperatures has been assessed to be below 1 ppm for CO and approximately 100 ppm for CH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> . The mainly digital implementation with a maximum sampling rate of 9.3 kHz for all three sensors offers the advantage to apply a power-saving mode and temperature modulation techniques to enhance the analyte discrimination capability

Development of the mold-temperature-control solidification device with individual temperature control units

An experimental device is developed for studying mold-temperature-control solidification(MTCS)process.The device includes the mold and temperature measure control system.In the mold,eight groups of individual heating and cooling units are distributed in proportional spacing.The mold is heated by 16 far-infrared heating pipes and mold cooling are processed by forced convection of the coolant in the machined channels.Eight thermocouples are used to measure the tran- sient temperature of the melt on different positions.According to the temperature data obtained by data collection module,the output control module signals to open or close the heating and cooling units.Thus the mold temperature can be automatically controlled.The flow control is implemented by developing the application based on the MCGS configuration software.The MCGS application can show the real-time and history graphs of the control points temperature and control the system by warn- ing and cyclic strategies.The results of numerical simulation and experiment indicate that the product has no defects like shrinkage cavities and the relative errors between the numerical and experimental data are less than 8 percent.

Thermal control of micro reverse transcription-polymerase chain reaction systems

Being beneficial from dramatic progress in biochemical and micro-electromechanical technologies, traditional DNA manipulation devices tend to be miniaturized to speed up detection processing. Polymerase chain reaction (PCR) and reverse transcription-polymerase chain reaction (RT-PCR) are two typical examples of them. In this report, micro RT-PCR (μRT-PCR) is designed to quantitatively detect viruses. Test samples reservoirs, RT-PCR, and capillary electrophoresis are integrated on a SU-8 based monolithic chip. A high-precision temperature control unit is well developed by embedding amplification circuits and an Intel 8051 microprocessor. The integrated system exhibits high efficacy of heat transfer, exemption of fluid flow clogging and adequate sensitivity to, by feedback, control the cycle of detection for the infected malignant tissues via intensive simulations.

Design and Control of a Piezoelectric Driven Fatigue Testing System for Electronic Packaging Applications

Failure of solder joints for electronic packaging is an important issue for controlling the reliability of semiconductor devices. However, the complicated coupling between mechanical stressing and temperature and time dependent material properties makes it difficult to explore the fundamental failure control mechanisms using the existing accelerated thermal cycling methods. In addition, the testing speed is also severely restricted by the thermal time constant of the characterization system. In order to decouple the mechanical stress effect from other factors as the first step toward exploring the control mechanisms of failure, a piezoelectric-based fatigue characterization system is developed to replace the thermal cycling and provide fast and purely mechanical stressing cycles. A self-tuning based (STR) adaptive controller is also developed to provide accurate process control during experiments for compensating stiffness variation due to fatigue crack growth. It is found that this STR regulator is more robust than the traditional PID controller. The bandwidth of the system is approximately 70 Hz and is currently restricted by the equivalent time constant of the piezoelectric material. Nevertheless, this speed is sufficient for conducting a successful fatigue testing of solder joints. Finally, preliminary fatigue experiments have been performed on Sn63Pb 37 solders and the reduction of stiffness due to crack growth is clearly visible while the actuation performance is consistent and stable during the entire testing period. In the future, it is possible to operate in conjunction with a temperature control unit and a creep testing scheme to explore both the temperature and time dependent nature of solders in order to fully understand the failure control mechanisms of packaging

New Developments in Cold Spray Based on Higher Gas and Particle Temperatures

In cold spraying, bonding is associated with shear instabilities caused by high strain rate deformation during the impact. It is well known that bonding occurs when the impact velocity of an impacting particle exceeds a critical value. This critical velocity depends not only on the type of spray material, but also on the powder quality, the particle size, and the particle impact temperature. Up to now, optimization of cold spraying mainly focused on increasing the particle velocity. The new approach presented in this contribution demonstrates capabilities to reduce critical velocities by well-tuned powder sizes and particle impact temperatures. A newly designed temperature control unit was implemented to a conventional cold spray system and various spray experiments with different powder size cuts were performed to verify results from calculations. Microstructures and mechanical strength of coatings demonstrate that the coating quality can be significantly improved by using well-tuned powder sizes and higher process gas temperatures. The presented optimization strategy, using copper as an example, can be transferred to a variety of spray materials and thus, should boost the development of the cold spray technology with respect to the coating quality.

Thermal trajectory control for micro RT-PCR biochips

Being beneficial from dramatic progress in bio-chemical and micro-electro-mechanical technologies, traditional DNA manipulation devices tend to be miniaturized to speed up detection processing. Polymerase chain reaction (PCR) and reverse transcription polymerase chain reaction (RT-PCR) are two typical examples of them. In this report, micro RT-PCR (μRT-PCR) is designed to quantitatively detect viruses. Test sample reservoirs, RT-PCR, and capillary electrophoresis are integrated on a SU-8 based monolithic chip. A high-precision temperature control unit is well developed by embedding amplification circuits and an Intel 8051 microprocessor. The integrated system exhibits high efficacy of heat transfer, exemption of fluid flow clogging and adequate sensitivity to, by feedback, control the cycle of detection for the infected malignant tissues via intensive simulations.

Characterisation of Thermal Expansion Coefficient of Anisotropic Materials by Electronic Speckle Pattern Interferometry

Abstract: Carbon fibre composites find wide applications in aerospace, sporting goods industry and biomedicine. Mechanical and thermal properties of such materials are highly anisotropic; therefore, adequate experimental measuring methods are requested to determine them. This paper describes the application of electronic speckle pattern interferometry to full‐field, real‐time characterisation of the coefficient of thermal expansion (CTE) of anisotropic materials. The topics such as correlation fringes tilt and influence of small rigid body rotation were theoretically described and experimentally verified. A series of measurements was carried out to determine the CTE tensor for unidirectional and bi‐directional carbon fibre laminates and to prove the feasibility of the method. The measuring set‐up developed includes a temperature control unit for cooling and heating and a one‐dimensional in‐plane speckle interferometer.

Thermoluminescence emission spectra for the LiF:Mg,Cu,Na,Si thermoluminescent materials with various concentrations of the dopants (3-D measurement)

The thermoluminescence (TL) emission spectra from LiF TL materials, called KLT-300 (LiF:Mg,Cu,Na,Si) with various dopant concentrations are measured and analysed. These KLT-300 materials were developed by the Korea Atomic Energy Research Institute (KAERI) to achieve an enhancement of the thermal stability in TL readings. Six types of samples are prepared with different dopant concentrations in the following ranges; Mg (0-0.20 mol%), Cu (0-0.05 mol%), Na and Si (0-0.9 mol%). The spectra measurements are carried out for the six types of samples using a TL emission spectra measurement device. The spectra measurement device consists of a monochromator, photomultiplier tube and temperature control unit to thermally stimulate the samples. The measured data shows the light emission during heating of the sample as a function of temperature and wavelength (three-dimensional TL spectra). The spectra were analysed using a method of deconvolution based on gaussian curve. The wavelength of a main peak of the emission spectra changes depending on the existence of the Cu dopant, while intensity of the spectra rapidly changes with the Cu dopant concentrations. The 385 nm emission is mainly observed in all the spectra from the samples with the Cu dopant, but in those from the samples without the Cu dopant a very weak 401 nm emission is mainly observed. However, any change in the wavelength at a main peak of the TL emission spectra from the sample materials with Na and Si dopants is not observed but that in the intensity at a peak of the spectra is observed.