Cavity optomechanics with ultra-high Q crystalline micro-resonators

We present the first observation of optomechanical coupling in ultra-high Q crystalline whispering-gallery-mode (WGM) resonators. The high purity of the crystalline material enables optical quality factors in excess of 10^{10} and finesse exceeding 10^{6}. Simultaneously, mechanical quality factors greater than 10^{5} are obtained, still limited by clamping losses. Compared to previously demonstrated cylindrical resonators, the effective mass of the mechanical modes can be dramatically reduced by the fabrication of CaF2 microdisc resonators. Optical displacement monitoring at the 10^{-18} m/sqrt{Hz}-level reveals mechanical radial modes at frequencies up to 20 MHz, corresponding to unprecedented sideband factors (>100). Together with the weak intrinsic mechanical damping in crystalline materials, such high sindeband factors render crystalline WGM micro-resonators promising for backaction evading measurements, resolved sideband cooling or optomechanical normal mode splitting. Moreover, these resonators can operate in a regime where optomechanical Brillouin lasing can become accessible

Anhedonia in the shadow of chronic social defeat stress, or When the experimental context matters

One of the core symptoms of major depression in human is anhedonia. For that reason, one of the main requirements towards experimental depression models is that they be able to demonstrate anhedonia in animals, that have been exposed to stressful events, and other behavioral changes attributable to a depression-like state. However, the results presented in the literature are contradictory: sweet solution intake, which is considered as a parameter of hedonic/anhedonic behavior in animals, responds quite differently to stressful situations in that it is either unaffected or increased or decreased. Different experimental designs used for the study of anhedonia in male mice exposed to chronic social defeat stress were tried to understand the reasons for so contradictory responses. Anhedonia appears as an abrupt reduction in sweet solution consumption in stressed animals and by failure to attain recovery after deprivation. However, it was also demonstrated that sucrose solution intake and preference strongly depend on the experimental context; that the possible critical factor may be prior acquaintance with the hedonic stimulus – or the lack whereof. Analysis of literature data and ours allowed us to conclude that the lack of a significant decrease in sweet solution intake in stressed animals is no evidence of lack of depression. This decrease is evidence of anhedonia only provided other symptoms of depression are present. Hedonic consumable intake can be decreased over various motivations, conditions or diseases, in particular, a high level of anxiety or pathological aggression

Synthesis and luminescence of lead(II)-activated cadmium sulfide in poly(methyl methacrylate)

Optically transparent polymeric materials PMMA: Cd(Pb)S have been synthesized by polymerization of methyl methacrylate, which concurrently acts as a reaction medium for synthesis of metal sulfides, dispersion medium for the resulting colloidal solution forming during synthesis, and the base of compositions. Dependences of cadmium sulfide luminescence on the concentrations, concentration ratios of the initial compounds, reaction medium composition, and temperature have been established. The observed changes in the spectra are related to the introduction of lead(II) into compositions, complex formation on the surface of colloidal particles, and the effect of polar acetonitrile

Synthesis and absorption and luminescence spectra of poly(methyl methacrylate):Cd(Mn,Pb)S composites

The reaction of cadmium, manganese, and lead trifluoroacetates with thioacetamide in methyl methacrylate yielded colloidal solutions of metal sulfides with different Cd(II): Mn(II): Pb(II) molar ratios. The colloidal particles were separated from solutions and examined by electron microscopy. Glassy polymer composites poly(methyl methacrylate):Cd(Mn)S and poly(methyl methacrylate):Cd(Mn,Pb)S were prepared by thermal polymerization of methyl methacrylate in the bulk. The transmittance of the composites at wavelengths larger than 480 nm is 92% at the sample thickness of 0.40 cm. The luminescence of the composites in the visible range is associated with cadmium sulfide. The corresponding absorption bands were recorded in the luminescence excitation spectra in the wavelength interval 300–450 nm. The effect of the matrix, Mn(II) and Pb(II) ions, and synthesis conditions on the absorption and luminescence properties of the composites was determined

Synthesis and spectral properties of colloidal solutions of metal sulfides

Cadmium, lead, and zinc sulfides as well as cadmium and lead (cadmium and zinc) complex sulfides have been synthesized in the colloidal state by reaction of metal trifluoroacetates with thioacetamide in ethyl acetate and methylmethacrylate. Synthesis products have been isolated from the reaction solutions and studied by X-ray diffraction, vibrational and electronic spectroscopy, and electronic microscopy. The effect of the composition on spectral properties of formulations has been discussed. The formation of colloidal particles and the stability of solutions are related to the complexation

Synthesis and luminescence spectra of poly(methyl methacrylate)/CdS:Ln(III) composites

Cadmium sulfide was prepared by colloidal synthesis in methyl methacrylate (MMA). Europium and terbium salts were added to the colloidal solutions. Using MMA radical polymerization, we synthesized PMMA/CdS:Eu(III), PMMA/CdS:Tb(III), and PMMA/CdS:Eu(III):Tb(III) luminescent composites. Their luminescence is due to defects in the CdS crystals and the 5Dо → 7Fj and 5D4 → 7Fj electronic transitions of the Eu3+ and Tb3+ ions, respectively. It depends on the composition of the materials, complexation on the surface of the colloidal particles, heat treatment time during synthesis, excitation wavelength, and other factors

Theory and Practice of Primary Adaptation as a Factor in Retaining Young Specialists at the Enterprises of the Mining Industry in Russia

The article is devoted to the urgent problem of retaining young specialists at the enterprises of the Russian mining industry. It defines the importance of such an important area of work of personnel management services, as primary adaptation, for the successful solution of this problem. The complex content of adaptation programs for young specialists is revealed and the main strategies for their retention in modern conditions are outlined. At the theoretical level of consideration of the problem, general scientific research methods were used, as well as specific sociological analysis and content analysis of the works of leading Russian scientists in the field of personnel management. The applied significance of the article is to describe the practical work of the personnel management services of the Joint Stock Company ALROSA to retain young specialists at the mining industry enterprises

Методики расчета продолжительности запекания изделий из мясного фарша при тепловой обработке в конвекционных печах

Saving energy resources, optimizing production processes and ensuring high quality of finished products are important tasks facing the food industry of the Republic of Belarus at the present stage of social and economic development. From this point of view, the current direction of scientific activity is development of methods for predicting duration of heat treatment of food products, which will allow to increase the level of production planning, implement production processes rationally, ensure production of finished products with high consumer parameters with no underheating or overheating of material of the processed bodies, and decrease the cost of energy resources for thermal processes. The paper proposes the method for theoretical calculation of baking duration for minced meat products in direct contact of the heating medium with the processed body in modern convection units. When developing a theoretical calculation, heat transfer processes are divided into internal and external. When describing internal heat transfer processes, changes in the thermal and physical characteristics of the material of the processed body are considered, determined by mass transfer processes and physical and chemical changes in structural elements with conversion of raw minced meat into finished product with baked crust. The processes of external heat exchange are described according to the operating parameters of modern convection ovens used in small and medium-sized enterprises of food industry and public catering. The values of duration of heat treatment on the example of products made of chicken mince at different temperatures of the heating medium are obtained. Special rod cassettes with a rigid thermocouple attachment design have been developed to ensure correct experiment. Deviations of baking duration values between the theoretically calculated and experimentally obtained values range from 1.49 to 4.44 % for different temperatures of heating medium, which indicates the efficiency of the developed technique. The proposed technique for calculating the duration of baking process for minced meat products when heated will allow optimizing production processes, saving energy resources and obtaining finished products with high consumer parameters. Acknowledgments. The research was carried out as part of the state program of scientific research “Quality and Efficiency of Agroindustrial Production”.Экономия энергетических ресурсов, оптимизация производственных процессов и обеспечение высокого качество готовой продукции – важные задачи, стоящие перед пищевой промышленностью Республики Беларусь на современном этапе социально-экономического развития. С этой точки зрения актуальным направлением научной деятельности является разработка методик прогнозного определения продолжительности тепловой обработки пищевых продуктов, применение которых позволит повысить уровень планирования производства, рационально осуществлять производственные процессы, обеспечить получение готовой продукции с высокими потребительскими характеристиками без недогрева или перегрева материала обрабатываемых тел, оптимизировать затраты энергетических ресурсов на проведение тепловых процессов. В работе предлагается методика теоретического расчета продолжительности запекания изделий из мясного фарша при прямом контакте греющей среды с обрабатываемым телом в современных конвекционных аппаратах. При разработке теоретического расчета процессы теплообмена разделены на внутренние и внешние. При описании процессов внутреннего теплообмена учтены изменения теплофизических характеристик материала обрабатываемого тела, обусловленные протекающими массообменными процессами и наличием физико-химических изменений структурных элементов с преобразованием сырого фарша в готовый продукт с запеченной коркой. Процессы внешнего теплообмена описаны согласно режимным параметрам современных конвекционных печей, применяемых в малых и средних предприятиях пищевой промышленности и общественном питании. Получены значения продолжительности тепловой обработки на примере изделий из куриного фарша при различных температурах греющей среды. Разработаны специальные стержневые кассеты с конструкцией жесткого крепления термопар, обеспечивающие проведение корректного эксперимента. Отклонения значений продолжительности запекания между теоретически – рассчитанными и полученными экспериментально составляют от 1,49 до 4,44 % для различных температур греющей среды, что свидетельствует о эффективности разработанной методики. Предложенная методика расчета продолжительности процесса запекания изделий из мясного фарша при нагревании позволит оптимизировать производственные процессы, обеспечить экономию энергетических ресурсов и получать готовую продукцию с высокими потребительскими характеристиками. Благодарности. Работа выполнена в рамках государственной программы научных исследований «Качество и эффективность агропромышленного производства»