Влияние качества агломерата и кокса на технико-экономические показатели доменной плавки

Introduction. Prognosis of root canal treatment is highly dependent on the quality of endodontic space obturation. The main task of successful root canal treatment is to achieve adequate reparation processes in the apical periodontium. The aim of this study was to evaluate the quality of root canal obturation using the method of gas (argon) penetration through three different endodontic materials. Material and Methods. Thirty recently extracted human single-rooted teeth after root canal instrumentation were divided into three identical groups and obturated with three different endodontic materials: group I - GuttaFlow (RSA, Germany), group II - AH Plus (DeTray, Germany), group III - Acroseal (Septodont, France). The quality of root canal obturation was evaluated using the method of gas permeability. Results. The best results were obtained with GuttaFlow. The average penetration rate of argon was 186.7 seconds. Slightly higher gas porosity had AH Plus, 179.9 seconds, while the highest gas permeability was observed after the application of Acroseal, 178.5 seconds. However, there was no statistically significant difference in gas penetration among these endodontic materials (p>0.05). Conclusion. All three endodontic materials showed gas permeability in a given time interval. The best quality of obturation was achieved with GuttaFlow, while the lowest quality was obtained with Acroseal.

The correlation of insufficient gas penetration and gas permeation to structural performance in gas-assisted injection-molded polystyrene parts, designed with gas channels having five different types of cross sections but with the same section area, was investigated via tensile experiments and bending tests. Test results were also compared with those of standard injection-molded parts. Based on the measured results, it was found that for specimens with insufficient gas penetration, under tensile test and bending test the breaking region occurred in the neighborhood of the gas front tip near the gas entrance. This indicates that the effect of the hollow core developed by the gas, resulting in reduction of the cross-sectional area, is larger than the effect of stress concentration or residual stress at the gas front tip. In tensile tests, it is evident that gas permeation and insufficient gas penetration show significant influence on the tensile properties of parts, lowering the ultimate tensile strength. Moreover, in bending tests, the stress concentration or residual stress occurring at the gas front tip of insufficient gas penetration and the surrounding area of gas permeation shows less significant influence on part bending properties. At the same time, the cross-sectional geometry plays an important role in determining bending properties. The present investigation provides part designers design guidelines for understanding the correlation of insufficient gas penetration and gas permeation to structural performance of gas-assisted injection-molded parts. © 1999 John Wiley & Sons, Inc. Adv Polym Techn 18: 303–313, 1999

Filling simulation and gas penetration modeling for gas-assisted injection molding

When growing medicinal plants, it is important not only to obtain a high yield, but also high-quality raw materials. A wide range of pharmacological effects of calendula is due to the content of the dominant complex of biologically active compounds (BAС) responsible for immune activity and antioxidant properties. These include flavonoids (rutin, narcissin) and carotenoids (β-carotene, lutein). Therefore, the aim of the research was to study the effect of growth regulators of natural origin on the quality of pot marigold raw materials obtained in the conditions of the forest-steppe of the Middle Volga region. The amount of flavonoids was determined in calendula flowers collected in the third decade of July, August, and September by differential spectrophotometry in terms of rutin at a wavelength of 408 nm. Quantitative determination of the content of calendula carotenoids in flowers was carried out by direct spectrophotometric method at an analytical wavelength of 450 nm in terms of β-carotene. The average flavonoid content in July was 3.27%. In the raw materials harvested in August, flavonoid number decreased by 0.24%, in September it increased to 3.36%. According to the Golden Sea variety, the dynamics of accumulation of the amount of flavonoids from 3.37 to 3.46% can be traced. The use of Biodux and Zircon growth regulators ensures high quality of raw materials with a carotenoid content of 160.8...184.7 mg/% and 160.9...204.1 mg/%, respectively, depending on the harvest periods. This indicates the possibility of using vegetable raw materials for the industrial production of calendula preparations.

Freezing has long been used to preserve high-value food products such as meat; fish; particular foods where the quality of the frozen product is significantly better than the alternative, such as peas; and increasingly for other convenience foods ranging from chipped potatoes to complete ready meals. Lowering the temperature of foodstuffs reduces microbiological and biochemical spoilage by decreasing microbial growth rates and by removing liquid water which then becomes unavailable to support microbial growth. Freezing refers to the storage of food at temperatures between −18 and −30°C. In general lower storage temperatures give a longer shelf life. For example soft fruits may be stored for between 3 and 6 months at −12°C but for 24 months and beyond at −24°C. Most meat has a shelf life of 6–9 months at −12°C and this increases to between 15 and 24 months at temperatures down to −24°C. In contrast, chilling is defined by a storage temperature range between −1 and 8°C and is used for meat, fish, dairy products and chilled recipe dishes prior to consumption. It has little or no effect on the nutritional content or organoleptic properties of food. Similarly, the freezing process itself has little or no effect on the nutritional value of frozen foods. Conversely the quality of the initial raw material cannot be improved by freezing and only high-quality raw materials should be selected for freezing. Thus the quality and nutrient content of any food at the point of consumption are dependent upon the quality of the original raw material, the length of storage and the storage conditions and the extent and nature of the freezing process.

Effect of relative humidity and temperature on gas transport in Matrimid®: Experimental study and modeling

To investigate the correlation between nurse job burnout and salivary lysozyme activity. The saliva samples of 131 subjects were collected at four time points for two consecutive days with saliva collection tubes. The acquisition time points were 8:00 (baseline concentration), 10:00 (morning), 15:30 (afternoon), and 17:30 (recovery period). At the same time every subjects completed the job burnout questionnaire to investigate their general demographic characteristics and job burnout level. The salivary lysozyme concentration was measured with ELISA. The data were analyzed by partial correlation analysis and multiple stepwise regression analysis. There were significant differences in the salivary lysozyme activity between subjects with different ages, working years, and education levels. The work period vitality and the average energy of ≤ 30 age group were higher than other two groups and the recovery energy was higher than >35 age group. Working period vitality, the average energy of group >15 years were less than ≤ 10 years group. The work period energy and the average energy of university (college) and above group were lower than high school (secondary) and the following group. Job burnout and its three dimensions had a significant negative correlation with salivary lysozyme concentration (P < 0.01). Depersonalization and emotional exhaustion were the negative impact factors for salivary lysozyme activity at baseline. Emotional exhaustion and personal fulfillment were the negative impact factors for salivary lysozyme activity during the working period. Personal fulfillment was the negative factor for salivary lysozyme activity during the recovery period and the average salivary lysozyme activity. Salivary lysozyme activity is sensitive for nurse job burnout, so it can be used as an objective evaluation index of job burnout.

A sustained supply of low-cost, high quality raw materials is essential for the future success of the U.S. forest products industry. To maximize stem (trunk) growth, a fundamental understanding of the molecular mechanisms that regulate cell divisions within the cambial meristem is essential. We hypothesize that auxin levels within the cambial meristem regulate cyclin gene expression and this in turn controls cell cycle progression as occurs in all eukaryotic cells. Work with model plant species has shown that ectopic overexpression of cyclins promotes cell division thereby increasing root growth > five times. We intended to test whether ectopic overexpression of cambial cyclins in the cambial zone of loblolly pine also promotes cell division rates that enhance stem growth rates. Results generated in model annual angiosperm systems cannot be reliably extrapolated to perennial gymnosperms, thus while the generation and development of transgenic pine is time consuming, this is the necessary approach for meaningful data. We succeeded in isolating a cyclin D gene and Clustal analysis to the Arabidopsis cyclin D gene family indicates that it is more closely related to cyclin D2 than D1 or D3 Using this gene as a probe we observed a small stimulation of cyclin D expression in somatic embryo culture upon addition of auxin. We hypothesized that trees with more cells in the vascular cambial and expansion zones will have higher cyclin mRNA levels. We demonstrated that in trees under compressive stress where the rates of cambial divisions are increased on the underside of the stem relative to the top or opposite side, there was a 20 fold increase in the level of PtcyclinD1 mRNA on the compressed side of the stem relative to the opposite. This suggests that higher secondary growth rates correlate with PtcyclinD1 expression. We showed that larger diameter trees show more growth during each year and that the increased growth in loblolly pine trees correlates with more cell divisions in the cambial meristem as expected. We isolated a promoter from a cambial specific gene and commenced development of transformation protocols for loblolly pine. Since our results show that cyclin D expression correlates with increased growth we continued with experiments to demonstrate the effect of cyclin overexpression upon tree growth. Vectors which constitutively express the cyclin D cDNA were constructed and transformed into a transgenic pine system through the collaboration with Forest Research, New Zealand. The transformation system for Pinus radiata is well established and we hoped to gain phenotypic information in a closely related pine, rather than await development of a robust loblolly pine transformation method. Transformation experiments were conducted by a biolistic method developed at Forest Research, NZ. A total of 78 transgenic embryogenic lines were generated and bulked up with a good representation of transgenic lines per construct. Transformed calli were originally identified by resistance to the antibiotic Geneticin contained in the medium. The transgenic nature of the selected lines was subsequently confirmed using histochemical GUS staining. To date, 10 out of 13 selected transgenic lines have produced embryos and we are currently harvesting the first transgenic plantlets. At present time 22 of those plantlets have been moved to GMO facilities. We will soon develop a strategy for assessing potential phenotypic differences between the transclones and non-transformed controls. Transgenic plants are being grown to a stage (approx. 1 year) when meaningful phenotypic evaluation can be conducted. The recent availability of 10,000 element loblolly pine cDNA microarray will permit the evaluation of cyclinD overexpression upon gene expression in transgenic Pinus.

In the process of transformation and development of the market mechanism in the development of food production, dairy enterprises in Ukraine have experienced a comprehensive decline, the destruction of the material base, reducing the volume and quality of food production. The transition to a market economy proved to be quite difficult and confusing for dairy enterprises, especially in a situation of very low effective demand of the population, low-availability loans, high inflation, elimination of government subsidies led to a shortage of funds and losses of such entities. The purpose of the article is to study the state of development of dairy enterprises and develop measures to improve their management. The state of development of milk processing enterprises of Ukraine is considered in the article. Identifying problems in providing raw milk to the relevant formations. The introduction of best practices in the creation of own raw material base by dairies is proposed. The vision of domestic scientists in the development of measures for the development of dairy farming and dairy enterprises has been studied. The experience of advanced milk processing enterprises is analyzed. It is proved that their creation at the expense of profits or expansion of existing farms together with state support of dairy farming will allow to solve a number of important tasks and provide additional jobs in the dairy industry. A set of measures to improve management in the dairy industry, which will include increasing the technological level of production, streamlining the organizational system, providing the production process with quality raw materials, developing strategies for entering EU markets due to the loss of the Russian market, ensuring and maintaining a management system quality and conducting socially-oriented advertising campaigns. A set of appropriate measures will improve the quality of raw materials, create additional jobs in rural areas and provide dairy plants with high quality raw materials. This, in turn, will increase the competitiveness of domestic dairies in both domestic and foreign markets and provide the population with high quality dairy products.

The world’s beer market has never been more diverse. Most beers are produced in modern and technologically advanced breweries that use high quality raw materials, thus resulting in minor differences of physical–chemical properties between various beers (of the same style). However, consumers focus on constant quality and sensory properties of their chosen beer. Sensory evaluation is not an easy task and involves flexible methods for determination of differences and changes between beers. It is commonly used in breweries to provide constant quality of finished products, but also to ensure the quality of different raw materials (water, malt, hops) and to minimize the influence of the production process on final quality of beer.

It is crucial to understand the conditions and influencing mechanisms of shale gas slip effect for predicting the productivity of shale gas reservoirs. This study focuses on the Carboniferous Hurleg Formation shales in the eastern Qaidam Basin and conducts gas permeability tests using different gases (He/N2), as well as geochemical and pore-structure tests. The slip behavior of different gases in micro- and nanopores as well as the anisotropy of gas permeability were analyzed and discussed. The results show that helium permeability is 1.81–3.56 times higher than nitrogen permeability, with a greater difference at lower pore pressures. These permeability differences are attributed to variations in gas molecule size and slip effects. Specifically, the slip effect of helium gas has a greater contribution to permeability at lower pore pressures, with a helium slip factor averaging 2.79 times that of nitrogen. The effective pore size of shale, calculated based on the helium slip factor, is 0.74 to 1.51 times larger than when nitrogen is used, with an average of 1.67 times. Helium molecules have smaller diameters and longer average molecular free paths, resulting in a more pronounced slip effect compared to nitrogen. While helium does not adsorb, nitrogen exhibits some adsorption, causing radial expansion during gas penetration. Furthermore, when testing with different gases, the horizontal permeability (S043∥; S052∥) is higher than the vertical permeability (S043⊥; S052⊥). The anisotropy of permeability is controlled by the pore system formed by the arrangement and combination of minerals. Calcium-rich samples (S052) tend to exhibit higher anisotropy compared to calcite-rich samples (S043). The effective pore size in the vertical sample is larger than that in the parallel sample, and the gas slip effect is significantly greater in the vertical sample. These findings provide valuable data for future studies on shale gas slip effects and productivity prediction.

Modified random hierarchical bundle model for predicting gas permeability of cement-based materials

Gas‐assisted injection molding can effectively produce parts free of sink marks in thick sections and free of warpage in long plates. This article concerns the numerical simulation of melt flow and gas penetration during the filling stage in gas‐assisted injection molding. By taking the influence of gas penetration on the melt flow as boundary conditions of the melt‐filling region, a hybrid finite‐element/finite‐difference method similar to conventional‐injection molding simulation was used in the gas‐assisted injection molding‐filling simulation. For gas penetration within the gas channel, an analytical formulation of the gas‐penetration thickness ratio was deduced based on the matching asymptotic expansion method. Finally, an experiment was employed to verify this proposed simulation scheme and gas‐penetration model, by comparing the results of the experiment with the simulation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2377–2384, 2003

Geosynthetic clay liners (GCL) are manufactured hydraulic barriers consisting of mineral and geosynthetic components. They belong to a group of geosynthetic products whose primary purpose is to seal and they have been used in many geotechnical and hydrotechnical applications, landfi lls and liquid waste lagoons for quite a while. They are used in landfill final cover systems to prevent the infi ltration of precipitation into the landfi ll body and the penetration of gases and liquids from the landfill into the atmosphere and environment. Laboratory and fi eld research and observations on regulated landfi lls have proven the eff ectiveness of GCL as a barrier for the infi ltration of precipitation into the landfi ll body as well as the drainage of fl uid beneath the landfill. Due to the presence of high concentrations of gases in the landfill body, there is a growing interest in determining the efficiency of GCL as a gas barrier. It was not until the last twenty years that the importance of this topic was recognized. In this article, current GCL gas permeability studies, the testing methods and test results of gas permeability in laboratory conditions are described.

The article describes the current state of the dairy industry in Ukraine. The quality of milk raw materials in agricultural enterprises and households is characterized. The price situation in the milk market is analyzed. In the course of the research it was proved that in the agricultural enterprises the number of cows decreases annually, the logistics are in critical condition. The emerging situation is gaining ground as the country turns from a dairy exporter into an importer. It is established that today one of the main problems is the provision of processing plants with high-quality raw materials. The conducted researches confirm that today only agricultural enterprises that carry out mechanical milking, purification and cooling of milk can provide the necessary quality of the produced milk. Households do not have the capacity to provide the necessary technological process of production. That is why milk produced in households meets the requirements of only the second grade or non-varietal. As a consequence, in most cases milk is purchased at low prices from the population, whereas in agricultural enterprises it is sold extra, higher and first grade. Therefore, the development of civilized trade requires quality certified products. It is established that the determining factor of the competitiveness of dairy products in the market is the quality of products. Without the use of high-quality raw materials, it is impossible to produce a competitive product. It is substantiated that the development of cooperatives, small and family farms and their involvement in the organized market is one of the priority tasks for improving the quality indicators and increasing the purchase prices for milk purchased from private households. Therefore, this problem must be solved by intensifying agrarian policy in the inseparable support for the development of the dairy industry on the basis of state support.