Technical University of Moldova
Recent publications
Premenstrual syndrome (PMS) is one of the most common disorders faced by women of reproductive age. More than 200 symptoms of varying severity associated with PMS have been identified. Because of the broad spectrum of action of PMS and its impact on quality of life, symptom relief is the main challenge of treating PMS and premenstrual dysphoric disorder (PMDD). The review aims to analyze and identify the potential impact of dietary and nutritional therapies on PMS and, respectively, for its better management. The study was conducted by accessing Internet databases such as PubMed, ScienceDirect, and Scopus and using relevant keywords such as PMS, symptoms, dietary patterns (DPs), macro and micronutrients, and supplements. The results showed that diet is an essential modulating factor in reducing and managing PMS symptoms. But research on the actual effect of foods and nutrients on PMS is sparse, sporadic, and studied with insufficient scientific rigor. No correlations were identified between the consumption of macronutrients and PMS: protein, fat, carbohydrates, and fiber, but the effectiveness of micronutrients, especially calcium, magnesium, vitamin D, B vitamins, and herbal supplements, was demonstrated. Researchers remain unanimous that the evidence is insufficient and limited to support their use as an effective treatment. Nevertheless, the results could contribute to providing quality information to help women and girls make evidence-based decisions regarding premenstrual health and the adoption of dietary and nutritional therapies.
In this paper, we show in a series of experiments on 10 nm thick SnS thin film-based back-gate transistors that in the absence of the gate voltage, the drain current versus drain voltage (ID–VD) dependence is characterized by a weak drain current and by an ambipolar transport mechanism. When we apply a gate voltage as low as 1 μV, the current increases by several orders of magnitude and the ID–VD dependence changes drastically, with the SnS behaving as a p-type semiconductor. This happens because the current flows from the source (S) to the drain (D) electrode through a discontinuous superficial region of the SnS film when no gate voltage is applied. On the contrary, when minute gate voltages are applied, the vertical electric field applied to the multilayer SnS induces a change in the flow path of the charge carriers, involving the inner and continuous SnS layer in the electrical conduction. Moreover, we show that high gate voltages can tune significantly the SnS bandgap.
High-quality Bi 1− x Sb x (0 ≤ x ≤ 0.2) bicrystals with nanowidth crystallite interfaces (CIs), exhibiting simultaneously superconductivity ( T c ≤ 21 K) and weak ferromagnetism, are studied. A number of unusual features of quantum transport are observed, which are due to topological changes of the Fermi surface of CIs layers, as well as the manifestation of some 3D topological phases of the matter. It is revealed that the flow of Dirac fermions is sensitive to the field orientation, and the localization process occurs only at the B||CIs plane. In doing so, the dependences of the Landau level index n on peak position [Formula: see text] at inclination interfaces are extrapolated to −0.5 if 1 /B n → 0, as expected for the massless Dirac fermions, while in crystallites and some twisting CIs with an increased degree of imperfection, electronic states are of the Schrodinger type, since n takes integer values. At Sb concentrations of x ∼ 0.04, the high-field thermomagnetic phenomena of CI layers exhibit behavior of the 3D topological semimetals, whereas in bicrystals with 0.07 ≤ x ≤ 0.2 they manifest typical features of the 3D topological insulators.
Selenium nanoparticles are attracting the attention of researchers due to their multiple applications, including medicine. The biosynthesis of selenium nanoparticles has become particularly important due to the environmentally friendly character of the process and special properties of the obtained particles. The possibility of performing the biosynthesis of selenium nanoparticles via the living culture of Arthrospira platensis starting from sodium selenite was studied. The bioaccumulation capacity of the culture, along with changes in the main biochemical parameters of the biomass, the ultrastructural changes in the cells during biosynthesis and the change in the expression of some genes involved in stress response reactions were determined. Protein, lipid and polysaccharide fractions were obtained from the biomass grown in the presence of sodium selenite. The formation of selenium nanoparticles in the protein fraction was demonstrated. Thus, Arthrospira platensis culture can be considered a suitable matrix for the biosynthesis of selenium nanoparticles.
A new technological approach for sintering Al-doped ZnO ceramics using chemical vapor transport (CVT) based on HCl has been developed. Among the advantages of the proposed sintering approach are: the low sintering temperature of 1070 °C; the absence of deviation in the diameter of ceramics after sintering; and the presence of Zn excess in the resulting material. The influence of dopant powder, concentration of Al, powder compacting pressure, and stoichiometric deviation on the density and conductive properties of ceramics has been investigated. Due to the relatively weak interaction of Al2O3 with HCl and limited solubility of Al in ZnO, a doping level about 2 at.% is recommended. A further increase in the dopant concentration significantly reduces the density and conductivity of the resulting material. A theoretical and experimental comparative analysis of the features of CVT sintering of ZnO doped with Al, Ga, and In was also carried out. ZnO:Al:Cl CVT ceramics with the resistivity of 9.5 × 10–3 Ω cm can be used as stable magnetron targets for ZnO thin films deposition with improved conductive properties. The influence of dopant powder, Al concentration, deposition temperature, and the gaseous medium of sintering target on the electrical properties of films are investigated and discussed.
Optical absorption measurements at high pressure have been performed in two phases of the ordered-vacancy compound (OVC) ZnGa2Se4: defect stannite (DS) and defect chalcopyrite (DC). The direct bandgap energy of both phases exhibits a non-linear pressure dependence with a blueshift up to 10 GPa and a redshift at higher pressures. We discuss the different behavior of both phases in these two pressure ranges in relation to the pressure-induced order-disorder processes taking place at cation sites. Measurements performed in both phases on downstroke after increasing pressure to 22 GPa show that the direct bandgap energy of the recovered samples at room pressure was 0.35 eV smaller than that of the original samples. These results evidence that different disordered phases are formed on decreasing pressure, depending on the cation disorder already present in the original samples. In particular, we attribute the recovered samples from the original DC and DS phases to disordered CuAu (DCA) and disordered zincblende (DZ) phases, respectively. The decrease of the direct bandgap energy and its pressure coefficient on increasing disorder in the four measured phases are explained. In summary, this combined experimental and theoretical work on two phases (DC and DS) of the same compound has allowed us to show that the optical properties of both phases show a similar behavior under compression because irreversible pressure-induced order-disorder processes occur in all adamantine OVCs irrespective of the initial crystalline structure.
In this work, sol-gel synthesis and luminescence properties of erbium and ytterbium doped BaTiO 3 (BaTiO3:Er,Yb) in porous anodic alumina are reported. Porous anodic alumina with its well-known tailor-made honeycomb structure was chosen as a template for the sol-gel synthesis of BaTiO 3 :Er,Yb. Porous anodic alumina was fabricated either on silicon wafer or aluminum foil. The sol corresponding to xerogel content of Ba 0,76 Er 0,04 Yb 0,20 TiO 3 was deposited on porous anodic alumina by spinning, which was followed by drying and heat treatment at a relatively low temperature 450 °C on aluminum foil or 800 °C on silicon. Porous anodic alumina known also as an optically anisotropic structure differed in the experiments by diameter of the pores and thickness. Evidently, all fabricated samples demonstrated a roomtemperature erbium upconversion luminescence under excitation in the continuous-wave (CW) mode with a focused 980 nm laser beam of a 200 mW diode module. Erbium upconversion luminescence is characterized by the bands at 410, 523, 546, and 658 nm, corresponding to the ² H 9/2 → ⁴ I 15/2 , ² H 11/2 → ⁴ I 15/2 , ⁴ S 3/2 → ⁴ I 15/2 and ⁴ F 9/2 → ⁴ I 15/2 .
In this paper, new aeromaterials are proposed on the basis of titania thin films deposited using atomic layer deposition (ALD) on a sacrificial network of ZnO microtetrapods. The technology consists of two technological steps applied after ALD, namely, thermal treatment at different temperatures and etching of the sacrificial template. Two procedures are applied for etching, one of which is wet etching in a citric acid aqua solution, while the other one is etching in a hydride vapor phase epitaxy (HVPE) system with HCl and hydrogen chemicals. The morphology, composition, and crystal structure of the produced aeromaterials are investigated depending on the temperature of annealing and the sequence of the technological steps. The performed photoluminescence analysis suggests that the developed aeromaterials are potential candidates for photocatalytic applications.
Privacy and mutual authentication under corruption with temporary state disclosure are two significant requirements for real-life applications of RFID schemes. This paper proposes two practical RFID schemes that meet these requirements. They differ from other similar schemes in that they provide reader-first authentication. Regarding privacy, our first scheme achieves destructive privacy, while the second one -- narrow destructive privacy in Vaudenay's model with temporary state disclosure. To achieve these privacy levels, we use Physically Unclonable Functions (PUFs) to assure that the internal secret of the tag remains hidden from an adversary with invasive capabilities. Both of our schemes avoid the use of random generators on tags. Detailed security and privacy proofs are provided.
In the context of forecasted climate change scenarios, the growth of forest tree species at their distribution margin is crucial to adapt current forest management strategies. Analyses of beech (Fagus sylvatica L.) growth have shown high plasticity, but easternmost beech populations have been rarely studied. To describe the response of the marginal beech population to the climate in the far east sites of its distribution, we first compiled new tree ring width chronologies. Then we analyzed climate–growth relationships for three marginal beech populations in the Republic of Moldova. We observed a relatively high growth rate in the marginal populations compared to core distribution sites. Our analyses further revealed a distinct and significant response of beech growth to all climatic variables, assessing for the first time the relationship between growth and vapor pressure deficit (VPD) which described how plant growth responds to drought. These results highlight that accumulated water deficit is an essential limiting factor of beech growth in this region. In conclusion, beech growth in the easternmost marginal population is drought-limited, and the sensitivity to VPD will need to be considered in future studies to update the forest management of other economic and ecologically important species.
The investigation of weather properties and clouds distribution in the stratosphere is rare, but essential for science. In this research, twenty years of satellite recordings showed the properties of stratospheric clouds approved by GIS (Geographical Information System) and Remote sensing (RS) techniques. This type of clouds covered a small area in the analyzed period, but the results were important for meteorological and climatological condition in the atmosphere. A very tiny layer of water vapor and their low concentration produces a small number of clouds throughout the year. The average altitude of the stratosphere varied between 12 km and 50 km. The stratosphere is very dry; only polar stratospheric clouds (PSCCl) may be found. This type of clouds appears near the poles in the winter season. This research provides the explanation on the climate properties of clouds (water content) in this layer of the atmosphere. The layers of this type of clouds present stable factor of meteorological stability, but have recently been influenced by climate change effects. The new findings of water in the stratosphere were made possible by precise analysis of satellite recordings. The estimated amount of water in the clouds in the stratosphere may be significant for potential cloud seeding in the future.
For the conventional vineyard, reducing the pesticide usage is the most important issue for converting to organic vineyard. In order to study the effect of pesticide usage on grape yeast, an investigation were designed in vintage 2020, ten vineyards (include two organic vineyards) with different treatment frequency index (TFI) were chosen, and the yeast population counted by two method: cultivate method and the direct epifluorescence technique (DEFT). The results show, the grape yeast from Moldova exist the viable but non-culturable (VBNC) state. In organic vineyards, less proportion yeast reach the VBNC, however the opposite conclusion draw from conventional vineyards. High TFI with high level VBNC yeast population, inversely, less culturable yeast. No matter in which yeast state, the treatment of powdery mildew is the most influential factor on yeast population.
This study focused on the development of a yogurt with an improved structure, texture and antioxidant activity level, by using apple pomace (AP) powder that was obtained in large quantities during the production of juices. The objective was to determine the sensory, physicochemical, textural and antioxidant characteristics of yogurt with the addition of AP powder (0.2–1.0%), during its shelf life. The physicochemical composition of AP was determined as follows: dietary fibers—62.73%, including pectin—23.12%; and the content of the antioxidant compounds in AP—total polyphenols (728.8 mg GAE/100 g DW), flavonoids (246.5 mg QE/100 g DW), tannins (63.54 mg TAE/100 g DW), carotenoids (4.93 mg/100 g DW) and the ability to inhibit the free radical (2433 µmol TE/100 g DW). AP addition reduces the yogurt fermentation time. The increase in the total dietary fiber content of up to 0.63% and in the insoluble fiber of up to 0.14% was attested in this study, as well as a significant increase in antioxidant activity, which correlated to the AP content. The addition of AP improved the textural properties of the yogurt during storage (20 days) and led to a significant reduction in syneresis. The influence of the AP content and the storage period on the textural characteristics and the overall acceptability of the yogurt samples were analyzed by the mutual information method. The AP content greatly influenced the yogurt’s quality, with the information analysis value for the overall acceptability being 0.965 bits. The analysis of the sensory and textural parameters of the yogurt during storage (1–20 days) demonstrated that samples with AP in proportions of 0.6–0.8% were evaluated with the highest score.
Clouds play an important role in maintaining the balance in the environment. Cloudiness can influence numerous important ecological drivers, including growth, survival and distribution of plants. The cloud cover dynamics and distribution may provide key information for delineating various types of plant and species distribution. During a year, different types of clouds on a territory can influence the distribution of plants and potential of cloud seeding. New properties of cloudiness may be important for new ecological patterns and new adapted values of ecological drivers. In the territory of the Republic of Moldova, 30 years of cloudiness were taken to show new distribution of clouds properties and their influence on sunflower (Helianthus annus L.) and grapes (Vitis vinifera). The main result of this research is the first established map with the location of water derived from cloud seeding. In the last decade (2010-2020), the cloudiness increased by more than 15%. Another important focus of this research is the possibility of cloud seeding in line with recent deficit of precipitation, especially in dry areas. The territory of Moldova has 37% of semiarid and 6% of arid zones. The distribution and the potential of cloud seeding has been analyzed by means of Remote Sensing and GIS techniques and methodology, along with the Moderate Resolution Imaging Spectroradiometer. Satellite data in the resolution of 1 km 2 were downloaded for the period between 1990 and 2020. The exact distribution of clouds helped to determine the belts for the potential irrigation of crops. Extremely low cloudiness and a long period of drought may jeopardize the agricultural sector in the Republic of Moldova, and therefore, the irrigation from alternative water sources is of utmost importance.
Porous InP templates possessing a thickness of up to 100 µm and uniformly distributed porosity were prepared by anodic etching of InP substrates exhibiting different electrical conductivities, involving an environmentally friendly electrolyte. Ni nanoparticles were successfully directly deposited by pulsed electroplating into prefabricated InP templates without any additional deposition of intermediary layers. The parameters of electrodeposition, including the pulse amplitude, pulse width and interval between pulses, were optimized to reach a uniform metal deposition covering the inner surface of the nanopores. The electrochemical dissolution of n-InP single crystals was investigated by measuring the current–voltage dependences, while the Ni-decorated n-InP templates have been characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The proposed technology is expected to be of interest for sensing and photocatalytic applications, as well as for the exploration of their plasmonic and magnetic properties.
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669 members
Lupan Oleg
  • Department of Microelectronics and Biomedical Engineering
Anatolie Casian
  • Department of Computers, Informatics and Microelectronics, Technical University of Moldova
Valeriu Dulgheru
  • Fundamentals of Machine Design
Anatolie Sochirean
  • Design of Machine Parts
Victor Zalamai
  • National Center for Materials Study and Testing
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