Гибридные режимы работы термоэлектрических модулей

It is suggested that thermoelectric coolers designing should not be limited to the extreme modes of their operation. In some cases, it is convenient to use the so called hybrid modes - a combination of the extreme mode of maximum coefficient of performance for large temperature differences and a general cooling mode for small ones. The proposed hybrid mode makes it possible to control the cooling capacity of the module and not to confine this value to that under the extreme operating conditions, the maximum coefficient of performance in particular.

Effect of Cooling Rate during Glazing on the Mechanical and Optical Properties of Monolithic Zirconia with 3 mol% Yttria Content

Glazing is the final heat treatment process in the manufacturing of a monolithic zirconia prosthesis. Herein, the effect of cooling rate during zirconia glazing was investigated. A 3 mol% yttria-stabilized tetragonal zirconia polycrystal was glazed at the general cooling rate suggested by the manufacturer, as well as at higher and lower cooling rates, and the differences in flexural strength, hardness, optical properties, and crystal structure were evaluated. A higher cooling rate did not affect the flexural strength, hardness, grain size, optical properties, or crystal structure; however, the Weibull modulus decreased by 1.3. A lower cooling rate did not affect the flexural strength, optical properties, or crystal structure; however, the Weibull characteristic strength increased by 26.7 MPa and the Weibull modulus increased by 0.9. The decrease in hardness and the increase in grain size were statistically significant; however, the numerical differences were negligible. This study revealed that a lower cooling rate provides more reliable flexural strength. Therefore, glazing can proceed at a general cooling rate, which takes 3–4 min; however, glazing at a lower cooling rate will provide a more consistent flexural strength if desired, despite being time-consuming.

Anomalous phenomena and geoecological situation in the Russian Far East

The development of the geosystems of the Russian Far East proceeds under the enormous but contradictory in nature double influence of the continent and the ocean and is carried out through the atmosphere. The goal is to characterize hazardous natural phenomena depending on the differentiated natural tension of the Far East (from maximum in the south to moderate in the north), often causing disasters and creating tense levels of the geoecological situation in general. The article presents comparative-geographical, geophysical, informational methods, as well as author’s development, etc. Further strengthening of the natural continentality of the entire region climate predetermines a directed increase in the geosystems development of the role of hazardous natural processes. If a sharp anthropogenic climate warming occurs, an accelerated rise in the level of the World Ocean is possible, which will cause increased abrasion, avalanches and landslides in the coastal zone. In case of a persisting general cooling, a general extremalization of the entire natural environment will occur. Crisis situations are, to a certain extent, predictable, which can help in optimizing rational nature management.

Non-obvious effects of montelukast – leukotriene receptor blocker: frigoprotective and anticonvulsant properties

The participation of arachidonic acid metabolism products – prostaglandins and leukotrienes – in the process of inflammation is a common pathogenetic link of cold injury and epilepsy. Montelukast is widely used for the treatment of bronchial asthma and allergic rhinitis as a leukotriene receptor blocker. However, the mechanism of action of the drug suggests a wider range of its pharmacological properties and the corresponding scope of application. This study is aimed to determine the effectiveness of montelukast as a potential frigoprotective and anticonvulsant drug. Experiments were performed on 73 white mice weighing 20-22 g on models of acute general cooling and pentylenetetrazol convulsions. Frigoprotective properties were studied at a temperature of –18°C, recording the lifetime. Montelukast ("Singular", 2 mg/kg), acetylsalicylic acid ("Aspirin", 50 mg/kg), celecoxib ("Celebrex", 74 mg/kg), diclofenac sodium ("Voltaren", 14 mg/kg) were administered intragastrically as a suspension in a prophylactic mode, 30 minutes before the cold injury. In the study of anti­convulsant activity, montelukast ("Singular", 4 mg/kg) and sodium valproate ("Depakin", 300 mg/kg) were admi­nistered intragastrically 30 minutes before stimulating convulsions by subcutaneous administration of pentylene­tetrazole (90 mg/kg). The latent period of convulsions, the number of convulsions per 1 animal, % of mice with clonic and tonic paroxysms, the severity of convulsions in points, the duration of the convulsive period, the lifetime of animals and lethality were recorded for an hour. On the model of acute general cooling, montelukast showed a dose-dependent frigoprotective effect at a dose of 2 mg/kg surpassing drugs with proven frigoprotective properties – acetylsalicylic acid and celecoxib. On the model of pentylenetetrazole-induced convulsions, montelukast statistically significantly reduced the integral indicator of anticonvulsant activity – lethality – by 2.57 times. Thus, the experiment proved the significant role of leukotrienes in the pathogenesis of cold injury and epilepsy and justified the feasibility of further study of the frigoprotective and anticonvulsant properties of montelukast – leukotriene receptor blocker a drug as for adjuvant therapy, especially when these pathologies are combined with bronchial asthma and allergic rhinitis.

Thermal Conductivity Properties of Summer Cooling Towels

This study evaluated the cooling properties of summer cooling towels of different brands by studying the liquid moisture management behavior. All the samples were found to provide a cooling effect at first contact after being wetted. The samples of Perfect Fitness showed the highest cooling effect followed, whereas N-rit, Cooldyxm and Ice Towel samples had the poorest cooling effect. Through this study, the general cooling effect of summer cooling towels in the market can be compared which provide some idea to the consumer for product selection.

Dynamics of the Level of Myeloperoxidase and Serum Calprotectin in Local Cold Injury

Relevance. Cold injury is defined as a complex of pathophysiological and pathomorphological changes arising as a result of local or general cooling of the human body. Endothelial dysfunction provokes a powerful cascade of cellular interactions with expressed excretory activity, which ultimately leads to a pronounced remodeling of microcirculation and a protracted process of inflammation in the focus of alterations. Aim of the study. To establish the dynamics of the level of myeloperoxidase and calprotectin in the serum of patients with local cold injury. Materials and methods. The study included 80 patients with III–IV degree lesions in the late reactive period and the period of granulation and epithelialization. The average age of patients was 38 ± 8 years. The myeloperoxidase level was measured on the 5th and 30th days from the moment of cryopreservation using multiplex analysis of blood serum. Results. The level of myeloperoxidase and serum calprotectin increases. In late reactive period (day 5), MPO level in patients with frostbite is 7.25 times higher in comparison with control values, in the period of granulation and epithelialization (day 30), it remains elevated, but only 3.63 times higher than in the control group. In the late reactive period, the level of calprotectin in the blood serum of patients with local cold injury was 4.6 times higher in comparison with control values, and on the 30th day of cryopreservation, the value of calprotectin was 4.5 times higher than in the control group. Changes in the level of myeloperoxidase and serum calprotectin reflect the flow of destructive and reparative mechanisms in tissues during local cold trauma and can be used in predicting an unfavorable prolonged course of the wound process.