Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Temperature environment”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 307 records · Page 17Linked to original sources
PubMed1992

A five-station hip joint simulator for wear rate studies.

The aim of the work has been the development of a hip joint simulator for comparative wear rate studies of long duration. A five-station apparatus has been designed, constructed and tested. Five total hip joints can be tested at the same time in identical conditions. The flexion-extension motion and the superior-inferior component of the joint contact force are incorporated. The motion is electromechanical and the loading pneumatic. The angle and load waveforms are fixed and simulate level walking. For accurate wear measurements each station employs a control prosthesis. The conditions of the control prosthesis in regard to loading, exposure to lubricant and environment temperature (37 +/- 1 degree C) are identical to those of the test prosthesis. The acetabular cups can be readily removed for periodic wear measurements and reassembled in exactly the original position. Extensive tests have shown that the simulator is a practical and reliable instrument in the wear rate studies of various designs of total hip joint.

Equipment Design↗
PubMed2004

Employing oxygen-plasma posttreatment to improve the laser-induced damage threshold of ZrO2 films prepared by the electron-beam evaporation method.

ZrO2 films are deposited by the electron-beam evaporation method. Parts of the prepared samples are post-treated with oxygen plasma at the environment temperature. The laser-induced damage threshold (LIDT) of the films increases from 15.9 to 23.1 J/cm2 after treatment with oxygen plasma. Compared with that of the as-grown samples, significant reduction of the average microdefect density and absorption are found after oxygen-plasma posttreatment. These results indicate that the oxygen-plasma posttreatment technique is an effective and simple method for reducing the microdefect density and absorption to improve the LIDT.

Journal Article↗
PubMed2006

Multiple parameter vector bending and high-temperature sensors based on asymmetric multimode fiber Bragg gratings inscribed by an infrared femtosecond laser.

We present a multiple parameter integrated fiber sensor that can detect vector bending and ambient temperature simultaneously with a single asymmetric multimode fiber Bragg grating. Multimode Bragg gratings were fabricated in an all-silica core fiber by an infrared femtosecond laser, which showed multiple transmission dips in the transmission spectrum. Bending and ambient temperature fluctuations affect the shapes of multiple transmission dips in different ways. In bending, different dips have different sensitivities. On the other hand, temperature fluctuations tended to influence the dips uniformly across different dips. By analyzing the changing spectrum of dips, one can distinguish the changes induced by bending or temperature fluctuations. Furthermore, the high thermal stability of Bragg gratings inscribed by an infrared femtosecond laser can make this double parameter fiber sensor work in very harsh, high-temperature environments.

Journal Article↗
PubMed2004

Drift increases the advantage of sex in RNA bacteriophage Phi6.

The pervasiveness of sex and recombination remains one of the most enigmatic problems in evolutionary biology. According to many theoretical models, recombination can increase the rate of adaptation by restoring genetic variation. However, the potential for genetic drift to generate conditions that produce this outcome has yet to be studied experimentally. We have designed and performed an experiment that reveals the effects of drift on existing genetic variation by minimizing the influence of variation on beneficial mutation rate. Our experiment was conducted in populations of RNA bacteriophage Phi6 initiated from a common source population at varying bottleneck sizes. The segmented genome of this virus results in genetic exchange between viruses that co-infect the same host cell. In response to selection for growth in a high-temperature environment, sexual lines outperformed their asexual counterparts on average. The advantage of sex attenuated with increasing effective population size, implying that the rate of adaptation was limited by clonal interference among segments caused by drift. This is the first empirical evidence that the advantage of sex during adaptation increases with the intensity of drift.

Bacteriophage phi 6↗
PubMed1995

[Sneddon syndrome. Report of 3 cases].

The Sneddon's syndrome consists of neurologic manifestations associated to the presence of livedo reticularis and cyanosis of the extremities. The pathological process is an endothelial obliteration of arterioles, leading to a reticular appearance of the skin, despite the environment temperature. The authors present three new cases, caucasian males with 7, 16 and 54 years of age. The youngest started with hemilateralized motor seizures and showed a porencefalic area in the CT scan. The oldest had livedo reticularis, acrocyanosis and started with hemilateralized motor seizures, and a hemiparesis as sequela; CT scan with parasagittal infarct and occlusion presented of one anterior cerebral artery on angiography. The third patient started with hemifacial seizures, developed a labioglossolaringeal paresis and dysarthria as sequela; CT scan and MRI showed multiple infarcts, with multiple occlusions of cortical branches on angiography. The skin biopsies showed endothelial vascular hyperplasia in all cases. Only one (54 years old) patient had a positive IgG antiphospholipid antibodies. The Sneddon's syndrome seems not to be so rare and have to be considered in the etiological investigation of cerebral infarcts, mainly in young people.

Adolescent↗
PubMed1998

[Ergonomic working conditions for the nursing team in a cardiology unit].

Aiming at finding out the ergonomics conditions of the nursing personnel in a hospital admission unit, the authors utilized as a methodological presupposition the search for a global experienced work situation through the analysis of some elements as: the man (nursing worker); the work activity (prescribed duty, real activities and work position) and the environment (temperature, noise and illumination). The authors selected the Cardiology admission unit for the site of their research. The results verified that the nursing workers the mentioned unit face problems related to salaries, work installations, relationship, work organization, levels of formation and the activities executed. The authors suggested some recommendations.

Cardiology↗
PubMed1996

Predicting long-term performance of irradiation polymers.

Material degradation occurs during and after irradiation sterilization. The degree of post-degradation can be accelerated by altering the temperature, environment, and irradiation dose. This article discusses methods to accelerate post-degradation and how this can be used as a predictive technique for evaluating new or improved polymer formulations.

Polymers↗
PubMed2000

[New physiopathological findings in paraproteinemias].

Apart from their antigen-recognising function, immunoglobulins have other physicochemical properties. The best described is cryoprecipitation of monoclonal and/or polyclonal immunoglobulins. The cryoprecipitation phenomenon is unique for each cryoglobulin, and depends on the intrinsic properties of the monoclonal immunoglobulin, the protein environment, temperature and the surrounding ionic concentrations. The complement activating properties of monoclonal immunoglobulins are also unique. We have described a series of monoclonal immunoglobulins which are able to activate the classical pathway of complement without the formation of antigen/antibody complexes. Analysis of the properties of these monoclonal immunoglobulins suggests new therapeutic strategies in oncology. Monoclonal chimeric antibodies, combining antibody specific against tumour antigens and strong complement activation, may be more damaging to tumor cells than currently used antibodies.

Complement Pathway, Classical↗
PubMedDate not supplied

[Features of the structure of fibrin clots, connected with conditions of gel formation].

Fibrinogen to fibrin conversion and then fibrin clot three-dimensional network formation is one of the final steps in the coagulation system activation. Different factors, such as the environment temperature and pH, ions, so on, render an effect on the fibrin gel formation. Recently, the presence or absences of interface between two phases influence on the fibrin gel structure during its formation have been shown. Studies of fibrin gel structure peculiarities formed at different conditions (between two phases and without one phase) are demonstrated in this article. The plasmin enzymatic hydrolysis of fibrin clots both with surface film and without it was investigated. Experimental data allow to make a conclusion that the fibrin clot structure changes depend on its essential influence on the plasmin hydrolysis process of these clots.

Electrophoresis, Polyacrylamide Gel↗
PubMed2002

Effect of carbon dioxide and ammonium removal on pH changes in polishing ponds.

If nutrient removal is to be obtained in ponds treating sewage, the pH must be raised so that ammonia can desorb and phosphates can precipitate. In this paper it is shown that the pH increase in ponds can be predicted quantitatively from simple stoichiometry, taking into consideration physical and biological carbon dioxide removal, ammonia stripping and calcium carbonate precipitation. Biological CO2 removal by photosynthesis is identified as the main process to effect pH increase in ponds. The rate of pH increase and consequently the required retention time depend on the net rate of CO2 consumption, the extent of ammonium stripping, the characteristics of the influent (alkalinity and pH) as well as factors concerning the environment (temperature) and dimensions (depth) of the pond. A high pH (range 9 to 10) can be obtained in about 5 days if digested sewage is used (low organic material concentration), climate conditions are favourable and the pond is shallow (< 0.5 m deep).

Adsorption↗
PubMed2001

[An experimental study of the computer-controlled equipment for delivering volatile anesthetic agent].

Our newly-designed computer-controlled equipment for delivering volatile anesthetic agent uses the subminiature singlechip processor as the central controlling unit. The variables, such as anesthesia method, anesthetic agent, the volume of respiratory loop, age of patient, sex, height, weight, environment temperature and the grade of ASA are all input from the keyboard. The anesthetic dosage, calculated by the singlechip processor, is converted into the signals controlling the pump to accurately deliver anesthetic agent into respiratory loop. We have designed an electrocircuit for the equipment to detect the status of the pump's operation, so we can assure of the safety and the stability of the equipment. The output precision of the equipment, with a good anti-jamming capability, is 1-2% for high flow anesthesia and 1-5% for closed-circuit anesthesia and its self-detecting working is reliable.

Anesthesia, Closed-Circuit↗
PubMed2003

[An epidemiologic study of diabetes mellitus in employees of Baotou Iron & Steel Company].

OBJECTIVE: To investigate prevalence of diabetes mellitus (DM), impaired glucose tolerance (IGT), impaired fasting glucose (IFG) in Baotou Iron & Steel Company and to provide scientific evidence for prevention and intervention of DM. METHODS: Prevalence of DM was studied in 20 221 workers aged 20 years and over (male 15 124 and female 5 097), with the criteria set by the American Diabetes Association (ADA, 1997), in Baotou Iron & Steel Company. RESULTS: Prevalence of DM, IGT and IFG was 3.22%, 3.48% and 2.09%, respectively in 20 221 subjects, adjusted for age, which increased with age, body mass index and waist to hip ratio, and 56.30% of them were newly-diagnosed. Family history of DM and overweight correlated to prevalence of DM, IGT and IFG, which was higher in mental workers than that in physical laborers. The lower level of education, the higher prevalence of DM, IGT and IFG. Prevalence of DM, IGT and IFG in the workers working under high-temperature condition had no significantly difference with that in the control group. Mean blood pressure was significantly higher in persons with DM, IGT and IFG than that in the normal controls. CONCLUSIONS: Age, overweight, obesity, family history of DM, mental work, low level of education, and history of gestation with a huge fetus all were risk factors for DM, IGT and IFG. There is no significant impact of high temperature environment on prevalence of DM, IGT and IFG.

Adult↗
PubMedDate not supplied

[Expression of genes of prophage P1 Escherichia coli in cells of phytopathogenic Erwinia].

It is shown that the temperate coliphage P1Cmcts100 can transduce resistance to chloramphenicol in the cells of phytopathogenic bacteria Erwinia horticola and E. carotovora subsp. atroseptica. In the latter case the extrachromosomal DNA is inherited by recipient cells as the authentic prophage P1. The prophage P1 expresses rectification-modification EcoP1, as well as the genes of lysogenic conversion in phytopathogenic erwinia. Here the character of superinfection of transductants of E. atroseptica g125 by erwiniophage ZF40, by certain carotovoricines and coliphage T21 changes. Besides, the expression of genes of prophage P1 leads to the increase of survival of E. atroseptica when raising the environment temperature. Under these conditions the trans mutagenesis of bacterial chromosome can precede, that permits considering the phage P1 as a special tool for studying the molecular genetics of erwinia.

Anti-Bacterial Agents↗
PubMed1991

[An experimental model of ischemic lesions of the small intestine].

Ischemic (necrotic) lesions of the small intestine are caused by the influence of elevated environment temperature on the rat. The initial change which was gained was a subnuclear vacuolization of the absorptive cells on the tips of the intestinal villi. Later on, the vacuoles blend into the subnuclear space which contains a serous exudate in some places. With the expansion of the subnuclear space the epithelium separates from the stroma, and after it's desquamation there comes to an autolysis of the denuded stroma of the intestinal villi. The lesions are comparable with lesions of the small intestine caused by hypothermia, shock, mesenterial blood vessel ligation in experimental models of other authors, and with ischemic lesions of the small intestine in humans as well. These changes can be considered as a nonspecific consequence of mesenterial ischemia in the appearance of which vascular factors play a key role.

Animals↗
PubMed1985

A physiologist's view of running economy.

The relationship between VO2 and velocity of running (running economy) has been rather casually dealt with until very recently, and there still remains considerable disagreement as to the importance of this variable. Various factors which have been shown, or appear, to affect running economy include environment (temperature, altitude, running surface), fatigue, age, weight, state of fitness, and inherent differences. That differences between individuals and within individuals can and do exist seems clear; the questions which need to be addressed in future research are: (1) What type of training is most effective in bringing about changes in running economy? and (2) How much change in economy can be expected with optimum training? Furthermore, it is suggested that running economy be investigated as an entity, so that changes that may take place with time or training can be more accurately related to their cause.

Aging↗
PubMed1982

Filtration deformability of rabbit pulmonary macrophage.

Rabbit PAM deformability was evaluated by positive-pressure filtration through Nucleopore membranes of well-specified pore diameter. The PAM filtration method was standardized and was influenced by apparatus variations (pore size, flow rate, cell concentration), environment (temperature, pH, divalent cations, protein concentration), and differences in PAM cell volume. The influence of phagocyte function on filtration deformability was evaluated by exposing PAMs to pharmacologic and physiologic agents with somewhat exclusive influences on phagocyte physiology. Agents that interact with microfilament contractile protein (N-ethylmaleimide, cytochalasin B) altered deformability profoundly, but no effect was observed with agents interacting with microtubules (vinblastine, colchicine). Agents that cause general PAM activation (phorbol myristate acetate) or stimulate chemotaxis (F-Met-Leu-Phe) increased deformability. On the contrary, PAM deformability was not changed by phagocytosis of Staphylococcus aureus or latex beads. Pharmacologic agents that alter PAM adhesion (aspirin, indomethacin, physiologic dose hydrocortisone) or inhibit glycolysis (2-deoxyglucose) had no influence on filtration deformability. Filtration PAM deformability reflects passive whole cell rigidity, which appears to be determined by the state of polymerization of the actin-myosin microfilament complex.

Animals↗