Institutul de Fizică Aplicată

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    СИНТЕЗ МНОГОКОМПОНЕНТНЫХ И МНОГОФУНКЦИОНАЛЬНЫХ ПОКРЫТИЙ В ПЛАЗМЕ НИЗКОВОЛЬТНОГО ИМПУЛЬСНОГО РАЗРЯДА
    (CEP USM, 2024) Михайлов, Валентин; Казак, Наталья; Ивашку, Сергей; Янакевич, Анатолий; Яцко, Спиридон
    The synthesis of multicomponent and multifunctional coatings in low-voltage discharge plasma using compact electrodes made of graphite, refractory metals such as titanium, tantalum and tungsten, as well as their powders has been studied. Optimised energy regimes (energy value of electric discharges) have been identified at which the most qualitative coatings (uniform and continuous) with the highest content of carbide phases were obtained, which provide high hardness and service life under wear conditions. The utilisation of powders as alloying materials in lieu of compact electrodes has enabled the attainment of significantly thicker coatings and an enhancement in the process's productivity. This will facilitate the expansion of the technology's potential applications.
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    СХОДСТВО И РАЗЛИЧИЕ СПЕЦИФИКИ ДЕФОРМИРОВАНИЯ СТАЛИ AISI 316L В УСЛОВИЯХ ТРЕНИЯ И УДАРНОЙ НАГРУЗКИ
    (CEP USM, 2024) Грабко, Дарья; Пырцак, Константин; Присакару, Андриан; Топал, Дарья; Вилотич, Марко; Вилотич, Драгиша; Шикимака, Ольга
    The paper studies the formation of a hardened nano-microstructured (NMS) surface layer on AISI 316L stainless steel using two methods: light friction and light impact loading. The studies have shown that the forming NMS layer has both common and different features that can affect the properties of the modified material in different ways. The common features of the NMS layer under friction and impact loading include the fragmentation of the grain structure, the appearance of slip bands inside the grains, an increase in the strength and plasticity parameters. On the other hand, some differences are noted: a different degree of hardening in the NMS layer compared to the original undeformed surface, different sizes of the NMS layer, etc. Based on the obtained results, it can be assumed that the friction method can be used to obtain a slightly strengthened NMS layer with a thickness of about 500 μm. The impact load method is preferable for obtaining a more strengthened NMS layer of thickness ≈15-20 μm.
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    DIAGNOSE OF BIOMOLECULES USING RAMAN INTERACTIONS OF THE LIGHT
    (CEP USM, 2024) Ţurcan, Marina
    It is particularly important by now to apply the light in processing and development of modern diagnostic. Here with, two basic aspects of the interaction of light with the substance are discussed: the nonlinear one of light interaction with the environment, and the cooperative aspect of interaction of photons with matter (atoms or biomolecules). One should mention the use of metamaterials for tissue decontamination where the specific form of contact surface plays an important role. Another goal of the present work is the study and use of the cooperative effects of bacteria and viruses located in the evanescent field of biomaterials during Raman interaction of light in ultraviolet region. A model is proposed based upon existing experiments which takes into account the local symmetry of biomolecules. New models emerging from the non-linear interaction of the atomic (molecular) subsystem and the electromagnetic field of cavity could be elaborated. The photons statistic is proposed for the diagnosis of the new collective processes.
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    SEDIMENTAREA PROTEINELOR SERICE ÎN PUNCTUL IZOELECTRIC LA ELECTROACTIVAREA ZERULUI
    (CEP USM, 2024) Paladii, Irina; Vrabie, Elvira; Bologa, Mircea; Vrabie, Valeria; Stepurina, Tatiana; Policarpov, Albert; Sprincean, Cătălina
    The electroactivation of whey generates the recovery of whey proteins into mineral protein concentrates, accompanied by a series of inter- and intramolecular changes through the activation of all the substances in the solid content, especially the protein content, which occur through the action of a series of protein aggregation mechanisms, in according to the classic chemical and biochemical properties of serum proteins. The variation of active acidity and redox potential in the cathode cell is not homogeneous, it expands during processing and ensures the sedimentation of serum proteins from whey at their isoelectric point, it demonstrates the influence of solid and protein content on the electroactivation of different types of whey and indicates the transition of aquacomplexes in hydrocomplexes, being more evident when processing whey with a low protein content.
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    OPTIMIZATION OF AN EHD PUMP CHARACTERISTICS
    (CEP USM, 2024) Motorin, Oleg; Bologa, Mircea; Podlesny, Igor
    Electrohydrodynamic pumps generate flow in dielectric liquids. Two injection type electrohydodynamic pumps with blade-blade with insulation coating type electrodes and grid-grid type electrodes made of bare wires and wires covered with perforated insulation have been studied. There was a movable flow-limiting partition in the interelectrode space of the second pump. The current-voltage and pressure-flow rate characteristics of the pumps are given when using pure transformer oil, transformer oil-butanol mixtures ans polyethylsiloxane liquid. The optimal interelectrode gap distance, conductivity of the medium and position of the flow-limiting partition has been established, which ensures maximum pressure (in transformer oil, the pressure was 1.8 times higher than in polyethylsiloxane liquid).
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    EXAMENUL DE BAC LA FIZIC{ – BARIERA DINTRE EVALUAȚI ȘI EVALUATORI
    (CEP USM, 2024) Cârlig, Sergiu; Bîzgan, Serghei; Rusu, Angela
    The participation of students in the BAC examination in PHYSICS is analyzed for the last three years, after the modification of the national curriculum and the syllabus for the examination. The authors’ experience as trainers is summarized and ways to increase the objectivity of the assessment of the Physics exam are discussed. Statistics are presented and conclusions are drawn.
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    OSCILATORUL ANARMONIC
    (CEP USM, 2024) Cârlig, Sergiu; Bardeţchi, Profirie; Ciornea, Viorel; Macovei, Mihai
    The article analyzes the influence of the non-linear terms of the restoring force at large deviations from the equilibrium position of an oscillating body (non-linear oscillator). Particularly, it is demonstrated, in an accessible way,that the oscillations of the anharmonic oscillator drastically differ from thoseof a harmonic one. The main reason lies in the fact the oscillator frequency ofthe nonlinear oscillator, at large deviations, begins to depend on the amplitudeof the oscillations.
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    CRYSTAL STRUCTURE AND HIRSHFELD SURFACE ANALYSIS OF 2,4-DIAMINO-6-PHENYL-1,3,5-TRIAZIN-1-IUM PERCHLORATE
    (CEP USM, 2024) Craciun, Nicoleta; Melnic, Elena; Fonari, Marina; Chişca, Diana
    Synthesis and characterization of new organic salt, 2,4-diamino-6-phenyl-1,3,5-triazin- 1-ium perchlorate (LH)(ClO4), in which NH ···O(N) hydrogen bonds play an essential role in stabilizing the crystal structure, were highlighted in the present study. The crystal structure was determined using single-crystal X-ray diffraction analysis, which reveals that the title compound crystallizes in the monoclinic centrosymmetric space group P21/c and contains one cation and one anion in the asymmetric unit. The unit cell parameters are a =13.8011(13) Å, b = 5.0674(5) Å, c = 16.6411(13) Å, and β = 91.930(9)˚. Also, the composition C9H10ClN5O4, of the discussed compound was confirmed by FTIR spectroscopy. From this research a decisive influence of hydrogen bonds on stability of the reported crystal is evidenced. The distribution of all types of intermolecular interactions was assessed by the Hirschfeld surface analysis method.
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    QUANTUM HYBRID SYSTEM’S DYNAMICS via ENVIRONMENTAL THERMOSTAT
    (2024) Ceban, Victor; Cecoi, Elena; Cârlig, Sergiu; Macovei, Mihai
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