Rapid Cooling Research Articles

A Pilot Study of Rapid Cooling by Cold Saline and Endovascular Cooling Before Reperfusion in Patients With ST-Elevation Myocardial Infarction

Experimental studies have shown that induction of hypothermia before reperfusion of acute coronary occlusion reduces infarct size. Previous clinical studies, however, have not been able to show this effect, which is believed to be mainly because therapeutic temperature was not reached before reperfusion in the majority of the patients. We aimed to evaluate the safety and feasibility of rapidly induced hypothermia by infusion of cold saline and endovascular cooling catheter before reperfusion in patients with acute myocardial infarction. Twenty patients with acute myocardial infarction scheduled to undergo primary percutaneous coronary intervention were enrolled in this prospective, randomized study. After 4 ± 2 days, myocardium at risk and infarct size were assessed by cardiac magnetic resonance using T2-weighted imaging and late gadolinium enhancement imaging, respectively. A core body temperature of <35°C (34.7 ± 0.3°C) was achieved before reperfusion without significant delay in door-to-balloon time (43 ± 7 minutes versus 40 ± 6 minutes, hypothermia versus control, P=0.12). Despite similar duration of ischemia (174 ± 51 minutes versus 174 ± 62 minutes, hypothermia versus control, P=1.00), infarct size normalized to myocardium at risk was reduced by 38% in the hypothermia group compared with the control group (29.8 ± 12.6% versus 48.0 ± 21.6%, P=0.041). This was supported by a significant decrease in both peak and cumulative release of Troponin T in the hypothermia group (P=0.01 and P=0.03, respectively). The protocol demonstrates the ability to reach a core body temperature of <35°C before reperfusion in all patients without delaying primary percutaneous coronary intervention and that combination hypothermia as an adjunct therapy in acute myocardial infarction may reduce infarct size at 3 days as measured by MRI. URL: http://www.clinicaltrials.gov. Unique identifier: NCT00417638.

Cryopreservation of Primordial Germ Cells by Rapid Cooling of Whole Zebrafish (Danio rerio) Embryos

The feasibility of cryopreservation of zebrafish (Danio rerio) primordial germ cells (PGCs) by rapid cooling (i.e., vitrification) of dechorionated whole embryos at the 14- to 20-somite stage was investigated. Initially, we examined the glass-forming properties and embryo toxicities of six cryoprotectants: methanol (MeOH), ethylene glycol (EG), glycerol (GC), dimethyl sulfoxide (DMSO), propylene glycol (PG) and 1,3-butylene glycol (1,3-BG). According to the results of glass-forming and embryo toxicity tests, pretreatment solution (PS) containing 2 or 3 M cryoprotectant and vitrification solution (VS) containing 5 M cryoprotectant and 0.5 M sucrose were prepared using each cryoprotectant. Dechorionated embryos, the PGCs of which were visualized by injection of green fluorescence protein-nos1 3'UTR mRNA, were cooled rapidly by plunging into liquid nitrogen after serial exposure to PS and VS. All embryos cooled with MeOH, PG and 1,3-BG showed ice formation during cooling, and few embryos had live PGCs after warming. Most embryos cooled with GC did not show ice formation; however, few embryos had live PGCs. All embryos cooled with EG and most embryos cooled with DMSO had live PGCs when the embryos did not show ice formation during cooling. Based on the number of live PGCs in fresh embryos, the maximum survival rates of PGCs recovered from embryos cooled with EG and DMSO were estimated to be about 40 and 20%, respectively. The present study indicates that rapid cooling of dechorionated whole embryos, especially using EG-based solutions, could be utilized as a simple and promising tool for cryopreservation of PGCs.

Nearly Monodispersion CoSm Alloy Nanoparticles Formed by an In-situ Rapid Cooling and Passivating Microfluidic Process.

An in siturapid cooling and passivating microfluidic processhas been developed for the synthesis of nearly monodispersed cobalt samarium nanoparticles (NPs) with tunable crystal structures and surface properties. This process involves promoting the nucleation and growth of NPs at an elevated temperature and rapidly quenching the NP colloids in a solution containing a passivating reagent at a reduced temperature. We have shown that Cobalt samarium NPs having amorphous crystal structures and a thin passivating layer can be synthesized with uniform nonspherical shapes and size of about 4.8 nm. The amorphous CoSm NPs in our study have blocking temperature near 40 K and average coercivity of 225 Oe at 10 K. The NPs also exhibit high anisotropic magnetic properties with a wasp-waist hysteresis loop and a bias shift of coercivity due to the shape anisotropy and the exchange coupling between the core and the thin oxidized surface layer.

Nanostructured Hypoeutectic Fe-B Alloy Prepared by a Self-propagating High Temperature Synthesis Combining a Rapid Cooling Technique

We have successfully synthesized bulk nanostructured Fe94.3B5.7 alloy using the one-step approach of a self-propagating high temperature synthesis (SHS) combining a rapid cooling technique. This method is convenient, low in cost, and capable of being scaled up for processing the bulk nanostructured materials. The solidification microstructure is composed of a relatively coarse, uniformly distributed dendriteto a nanostructured eutectic matrix with α-Fe(B) and t-Fe2B phases. The fine eutectic structure is disorganized, and the precipitation Fe2B is found in the α-Fe(B) phase of the eutectic. The dendrite phase has the t-Fe2B structure rather than α-Fe(B) in the Fe94.3B5.7 alloy, because the growth velocity of t-Fe2B is faster than that of the α-Fe with the deeply super-cooling degree. The coercivity (Hc) and saturation magnetization (Ms) values of the Fe94.3B5.7 alloy are 11 A/m and 1.74T, respectively. Moreover, the Fe94.3B5.7 alloy yields at 1430 MPa and fractures at 1710 MPa with a large ductility of 19.8% at compressive test.

Abstract 2052: A Rapid Cooling of The Brain Using Percutaneous Cardiopulmonary Bypass Significantly Improves Neurological Function in Patients with Out-of-Hospital Cardiogenic Cardiac Arrest

Objectives: Neurological recovery in patients (pts) with out-of-hospital cardiogenic cardiac arrest (OHCCA) is affected by the cerebral circulatory collapse time from the cardiac arrest to the return of spontaneous circulation. According to recent studies, the cerebral circulatory collapse time is estimated to be 30 min. or less in order to successfully recover neurologically. In addition, percutaneous cardiopulmonary bypass (PCPB) is a powerful tool for rescuing the pts with OHCCA refractory to advanced cardiovascular life support (ACLS), and we have been positively performing cardiopulmonary cerebral resuscitation and rapidly cooling of the brain using PCPB. In this treatment, the cerebral circulatory collapse time is the duration from cardiac arrest to the start of PCPB, we discovered the fact that there are many neurologically successful cases of recovery even though the cerebral circulatory collapse time has exceeded 30 min. In the present study, we investigated the neurological prognosis in relation to the cerebral circulatory collapse time. Methods: From January 2006 to April 2008, 77 consecutive pts with OHCCA, who have been treated with brain hypothermia at 34 degree C were included. 77 pts were divided into two groups. Brain hypothermia (BH) groups (n=34) were treated with only brain hypothermia after the return of spontaneous circulation, and PCPB groups (n=33) were treated with hypothermia using PCPB against refractory to ACLS. The relation between the cerebral circulatory collapse time and the neurological prognosis were assessed. Results: The cerebral circulatory collapse time were from 8 min. to 78 min. in the BH groups, whereas it lasted from 22 min. to 91 min. in PCPB groups. In BH groups, the cases with the favorite neurological outcome were 23 cases (67.6%) and the average collapse time was 19.2 min. (8 to 35 min.) In contrast, in the PCPB groups, the successful neurological cases were 15 cases (45.5%), the average collapse time was 43.6 min (22 to 60 min.) In the cases who received PCPB, there were cases of neurologically successful prognoses even though the cerebral circulatory collapse time was long. Conclusions: These results suggest that a rapid cooling of the brain using PCPB permits a cerebral circulatory collapse time.

Pulsed Laser-Induced Rapid Surface Cooling and Amorphization

In this work, hybrid atomistic-macroscale simulation is conducted to explore the crystallization and amorphization of Si surface in the situation of fast melting and solidification induced by ultrafast laser heating and heat conduction. Our work is focused on investigating the relationship between the amorphization threshold (Ec) and the laser pulse width (tg). An empirical correlation Ec=448.76×tg0.56 is obtained to relate the critical fluence to the laser pulse width. By exploring the microstructure of the amorphous and crystalline state of Si, a sharp interface of about 0.6 nm thickness is observed between the amorphous layer and the crystalline Si. The relationship between the final thickness of amorphous layer and the fluence of the laser pulse is further studied in this work. Employing laser pulses with full width at half maximum (FWHM) equal to 6.67 ns, the formation and recrystallization processes of a 12-nm-thick amorphous layer is investigated.

Effect of As-Mold Rapid Cooling on Shrinkage and Morphology of Core Region of Injection Molded Parts Using Microcellular Foaming Process

Shrinkage is a common problem in injection molded parts which considerably affects the dimensional accuracy of the product. In this paper normal cooling (NC) and as-mold rapid cooling (RC) of core region of injection molded samples have been used to study the% shrinkage of Acetal copolymer with increased weight reduction using Microcellular Foaming Process (MCPs). The results show that shrinkage reduction is not only associated with weight reduction (WR) but also directly related with the decrease in crystalline phase and as-mold RC rate.14% decrease in linear shrinkage by NC with 5.5% loss in crystallinity and 24% decrease in linear shrinkage with 9% loss in crystallinity with RC were observed at 10% weight reduction at same mold temperature. Furthermore, RC of core region resulted into decreased cells size and increased cells density. The study can be useful to control the dimensional tolerances and morphology of the injection molded parts by RC of still molten core region.

Effects of Ti Addition on the Liquid-Phase Separation of Cu71Cr29 Alloy during Rapid Cooling

The effects of Ti addition on the liquid-phase separation of Cu71Cr29 alloy have been investigated. It is revealed that Ti addition can partly suppress the liquid-phase separation of the alloy melts, resulting in refining of Cr-rich particles formed after liquid-phase separation during rapid cooling. Nanoscaled Cr2Ti and Cu4Ti phases precipitate in the annealed Cu-Cr-Ti ribbons when Ti content attains 2.5 pct. The thermodynamic analyses indicate that the large positive mixing heat between Cu and Cr is reduced by the addition of Ti, leading to the liquid-phase separation occurring at a lower temperature and being driven by a smaller force. However, more Cr and Ti dissolve in Cu solid solution when Ti content is more than 3 pct, and as a result, the electrical resistivity of the ribbons is increased sharply.

Grain Refinement of C–Mn Steel to 1 μm by Rapid Cooling and Short Interval Multi-pass Hot Rolling in Stable Austenite Region

A noble grain refinement method to attain ferrite grain size of 1 μm in plain C-Mn steel by multi-pass hot rolling in a stable austenite temperature region has been explored. 0.1%C-1%Mn and 0.16%C-0.7%Mn steels were finish-rolled at about Ae 3 and then rapidly cooled. Special emphases have been placed on the interval, At, between the finish of rolling and the start of water spray cooling of more than 1000°C·s -1 in cooling rate and the interval between the last two rolling passes. By reducing At from 0.5 to 0.05 s alone, the grain sizes near the sheet surface and in the central region were markedly reduced to 1.3 and 2.2 μm respectively. By reducing At and the rolling pass interval together, a further reduction in grain size was then achieved. Consequently, the steel sheet in which the ultrafine grain structure of about 1 μm in grain size penetrated from the sheet surface to the depth of a quarter of the sheet thickness and the grain size in the central region was well below 2 μm was obtained. The transformation to the ultrafine ferrite is considered to be static and from deformed y. The detailed grain refinement mechanisms are discussed based on the microstructure observation of quenched C-Mn steels and a fcc Ni-30%Fe alloy as well as the calculation of prior y texture by the misorientation distribution function method.

Pulsed Laser Heating-induced Surface Rapid Cooling and Amorphization

ABSTRACTIn this work, hybrid atomistic-macroscale simulation is conducted to explore the crystallization process of Si surface in the situation of fast melting and solidification induced by ultrafast laser heating and heat conduction. Using the environment-dependent interatomic potential, samples containing 2,880 and 11,520 Si atoms are modeled to provide accurate details for the relationship between the finial crystal structure and the parameters of laser pulses. For different pulsed lasers, amorphous layers are found to form when the laser fluence exceeds a certain critical value. An empirical correlation Ec = 448.76 × (tg)0.56 is obtained to relate this critical fluence to the laser pulse width. It is found that the final thickness of amorphous layer is related to the fluence of the laser pulse with the same full width at half maximum (FWHM). Employing laser pulses with FWHM = 6.67 ns, the formation and recrystallization processes of a 12 nm thick amorphous layer is further investigated, which may have great potential in laser manufacture techniques for Si-associated structures.

Abstract 73: Rapid Whole Body Cooling in Large Swine: Effects on Heart Rate and Arterial Blood Pressure

There have been recent reports of a variety of cooling methods for reducing the body temperature of victims of post resuscitative syndrome. In the work reported here we cooled a series of large (&gt; 60 kg) domestic swine (n=6) using a whole body approach. The animals were anesthetized using propofol and buprinorphine and instrumented with arterial pressure monitoring and ECG, and thermocouple sensors in the pulmonary artery (PA), carotid artery, tympanic membrane and esophagus. With an initial average PA temperature at 37 (± 0.3) °C, the swine underwent a rapid cooling sequence. This was performed with a flexible surround suit system that provided for a thin 0.5 cm layer of circulating ice water in direct skin contact held between 0.5° and 1.5 °C. A pumping system was used to circulate the water volume of 20 liters at a rate of 15 liters per minute. The average PA temperature at the start was 37 (±0.3) °C. Cooling was targeted at 34 °C with an average value of 34.1 (±0.3) °C. Time to fall 3°C was13.0 (±3.0) min. At the same time, heart rate dropped (although not significantly) from 71 ± 7.9 BPM to 59.5 ± 11.4 BPM while mean carotid pressure dropped from 100.3 ± 16 mmHg to 77.3 ± 14.9 mmHg (p&lt;.05). We interpret these changes as beneficial reductions in cardiac work while the subject is kept cool. It is hypothesized that this is due to a reduction in total body metabolic demands. Thus it is possible, in addition to positive neurological effects, that the process of rapid whole body cooling also may be effective in reducing total workload seen by the heart, and thus may aid in salvaging myocardium in such patients.

Formation and Magic Number Characteristics of Cluster Configurations During Rapid Cooling Processes of Liquid Metals

A molecular dynamic simulation study has been performed for a large-sized system consisting of 106 liquid metal Al atoms to deeply investigate the formation and magic number characteristics of various cluster formed during solidification processes. It has been found that the numbers of various types of cluster in the system obviously possess peak values, namely, magic numbers. The first, second, third, .…,and tenth magic numbers are determined in turn in the order of 13, 19, 25(27), 31(33), 38(40), 42(45), 48(51), 55(59), 61(65), 67,…( the numbers in the brackets are the second peak values in the corresponding level of cluster). This magic number serial is in good agreement with the experimental results obtained by Harris et al, and this method determining the magic numbers from the clusters according to the level of basic cluster can be used to afford a primary scientific and reasonable explanation to experimental results.

A New Method of Selective, Rapid Cooling of the Brain: An Experimental Study

To determine whether retrograde perfusion of cooled blood into one internal jugular vein (IJV) in the pig can selectively reduce the brain temperature without affecting the core body temperature (CBT). In 7 domestic pigs, the left IJV was catheterized on one side and a catheter placed with the tip immediately below the rete mirabile. Thermistors were placed in both brain hemispheres and the brain temperature continuously registered. Thermistors placed in the rectum registered the CBT. From a catheter in the right femoral vein blood was aspirated with the aid of a roller pump, passed through a cooling device, and infused into the catheter in the left IJV at an initial rate of 200 ml/min. Immediately after the start of the infusion of cooled blood (13.8 degrees C) into the IJV, the right brain temperature started to drop from its initial 37.9 degrees C and reached 32 degrees C within 5 min. By increasing the temperature of the perfusate a further drop in the brain temperature was avoided and the brain temperature could be kept around 32 degrees C during the experiment. In 4 of the animals a heating blanket was sufficient to compensate for the slight drop in CBT during the cooling period. We conclude that brain temperature can be reduced in the pig by retrograde perfusion of the internal jugular vein with cooled blood and that the core body temperature can be maintained with the aid of a heating blanket.

Rapid Brain Cooling by Hypothermic Retrograde Jugular Vein Flush

Although whole-body hypothermia recently has been reported effective in improving the neurologic outcome after cardiac arrest, it is contraindicated in the management of trauma patients with hemorrhagic shock. To provide selective brain cooling in this situation, the authors speculated about the feasibility of hypothermic retrograde jugular vein flush (HRJVF). This preliminary study was conducted to test the effectiveness of brain cooling after HRJVF in rats without hemorrhagic shock. After jugular vein cannulation with cranial direction, Sprague-Dawley rats were randomized into a normal control group, a group that underwent flush with cold saline at 4 degrees C, or a group that underwent flush with saline at a room temperature of 24 degrees C. A Servo-controlled heat lamp was applied for all the rats to keep their rectal temperature at 37 +/- 0.5 degrees C. Their brain temperature and cerebral blood flow were checked. Within the 10-minute period of cold saline flush (1.7 mL/100 g), brain temperature was immediately decreased, and this cooling effect could be maintained for at least 20 minutes. Cerebral blood flow was significantly increased after HRJVF, then returned gradually to the baseline as brain temperature elevated. This study successfully demonstrated a significant cooling effect in rat brain by HRJVF. For preservation of brain function, HRJVF may be useful in resuscitation for trauma patients with hemorrhagic shock after further studies on animals with shock.

Evolvement on the Microstructure of Molten Compound AuCu&lt;SUB&gt;3&lt;/SUB&gt; in Rapid Cooling

Evolvement on the Microstructure of Molten Compound AuCu&lt;SUB&gt;3&lt;/SUB&gt; in Rapid Cooling

415 円管内を通過する流体の急速冷却装置の開発(熱工学 II,2.学術講演)

415 円管内を通過する流体の急速冷却装置の開発(熱工学 II,2.学術講演)

507 多層溶接における溶接直後急冷による残留応力低減挙動の熱弾塑性解析(OS-5B 金属の変形と損傷,OS-5 材料の塑性挙動の構成式のモデル化とシミュレーション)

507 多層溶接における溶接直後急冷による残留応力低減挙動の熱弾塑性解析(OS-5B 金属の変形と損傷,OS-5 材料の塑性挙動の構成式のモデル化とシミュレーション)

The Effects of Rapid Cooling on the Structure and Morphology of Silicon Nanoparticles

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

All three ryanodine receptor isoforms generate rapid cooling responses in muscle cells.

The rapid cooling (RC) response in muscle is an increase in cytoplasmic Ca2+ concentration ([Ca2+]i) that is probably caused by Ca2+ release from the sarcoplasmic reticulum (SR). However, the molecular bases of this response have not been completely elucidated. Three different isoforms of the SR Ca2+ release channels, or ryanodine receptors (RyRs), have been isolated (RyR1, RyR2, and RyR3). In the current investigation, the RC response was studied in RyR-null muscle cells (1B5) before and after transduction with HSV-1 virions containing the cDNAs encoding for RyR1, RyR2, or RyR3. Cells were loaded with fluo 4-AM to monitor changes in [Ca2+]i and perfused with either cold ( approximately 0 degrees C), room temperature (RT), or RT buffer containing 40 mM caffeine. Control cells showed no significant response to cold or caffeine, whereas robust Ca2+ transients were recorded in response to both RC and caffeine in transduced cells expressing any one of the three RyR isoforms. Our data demonstrate directly that RyRs are responsible for the RC response and that all three isoforms respond in a similar manner. Ca2+ release from RyRs is likely caused by a RC-induced conformational change of the channel from the closed to the open state.

Rapid Cooling of Dusty Gas in Elliptical Galaxies

We propose a stellar origin for the central dust clouds observed in most giant elliptical galaxies. Dusty gas ejected from evolving red giant stars in elliptical or cD galaxies can cool rapidly even after entering the hot X-ray-emitting gas. Cooling by thermal collisions with dust grains can be faster than either the dynamical time in the galactic potential or the grain sputtering time. Some grains survive in the cooled gas. Dusty stellar outflows cool more efficiently in the central regions, where the stellar metallicity is higher. Mergers with gas and dust-rich dwarf galaxies may occasionally occur but are not required to explain the observed dust clouds.