ẢNH HƯỞNG CỦA NHIỆT ĐỘ, THỜI GIAN VÀ TỐC ĐỘ GIA NHIỆT ĐẾN HÌNH THÁI CỦA VẬT LIỆU SnO2

In this work, rod-flower-like SnO2 hierarchical micro-nanostructures are successfully synthesized via pyrolysis of SnO2/chitosan in a nitrogen atmosphere. The effects of the heating temperature, time and rate of the thermolysis on the morphologies of the as-prepared products were evaluated. The optimized parameters to synthesis flower-like ensembles composed of nanorods found are as follows: temperature 500 °C, time six hours, and heating rate 10 °C/min. The structural properties of the material are systematically investigated by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The mechanism of the material formation is proposed.SnO2 có cấu trúc đa cấp hình bông hoa dạng que đã được tổng hợp bằng cách tiến hành nhiệt phân SnO2/chitosan trong môi trường khí nitơ. Các yếu tố ảnh hưởng đến hình thái của sản phẩm đã được khảo sát bao gồm nhiệt độ nung, thời gian nung và tốc độ gia nhiệt. Kết quả cho thấy tiến hành nung SnO2/chitosan trong khí nitơ ở 500 °C trong 6 giờ với tốc độ gia nhiệt 10 °C/phút thu được sản phẩm SnO2/cacbon có dạng màng bền và giữ nguyên hình dạng của màng SnO2/chitosan ban đầu, SnO2 có tính tinh thể cao và có cấu trúc đa cấp hình bông hoa. Vật liệu được đặc trưng bằng phương pháp nhiễu xạ tia X, hiển vi điện tử quét và phân tích nhiệt trọng lượng. Quá trình hình thành cấu trúc đa cấp hình bông hoa dạng que của SnO2 đã được đề nghị.SnO2 có cấu trúc đa cấp hình bông hoa dạng que đã được tổng hợp bằng cách tiến hành nhiệt phân SnO2/chitosan trong môi trường khí nitơ. Các yếu tố ảnh hưởng đến hình thái của sản phẩm đã được khảo sát bao gồm nhiệt độ nung, thời gian nung và tốc độ gia nhiệt. Kết quả cho thấy tiến hành nung SnO2/chitosan trong khí nitơ ở 500 °C trong 6 giờ với tốc độ gia nhiệt 10 °C/phút thu được sản phẩm SnO2/cacbon có dạng màng bền và giữ nguyên hình dạng của màng SnO2/chitosan ban đầu, SnO2 có tính tinh thể cao và có cấu trúc đa cấp hình bông hoa. Vật liệu được đặc trưng bằng phương pháp nhiễu xạ tia X, hiển vi điện tử quét và phân tích nhiệt trọng lượng. Quá trình hình thành cấu trúc đa cấp hình bông hoa dạng que của SnO2 đã được đề nghị

Extract and fraction of cashew nut testa ameliorate the hyperglycemic mice induced by Streptozotocin and high-fat diet

Drug strategy is a standard method for treating type 2 diabetes mellitus (T2D), a non-communicable disease with increasing prevalence, which may cause side effects. Therefore, natural compounds with limited adverse effects have come back into vogue for treating T2D. This study aims to evaluate the effects on rehabilitating hyperglycemic mice of cashew nut testa (husk) extract and fraction known as potential bio-substances for improvement in T2D. First, the hyperglycemic mice were induced with a high-fat diet (HFD) for 4 weeks and then were injected with streptozotocin (STZ, dozen for injection was 40 mg/kg/week) for 2 weeks. Next, the confirmed hyperglycemic mice were treated with pioglitazone (HG+PG group), total extract (HG+TE group), and saponin-rich fraction (HG+SRF group) for 3 weeks. Then, the evaluation was based on body mass; blood glucose (BG) level; BG tolerance, lipid profile, pancreatic histology and the expression IRS-1 in the pancreas. The results showed that body mass and BG level significantly increased in hyperglycemic mice. After substance treatment, there was no change in body mass in TE and SRF groups. However, BG level of HG+TE group mice significantly decreased compared to hyperglycemic mice and only BG tolerance of HG+SRF group was improved. Besides, HG+TE and HG+SRF groups modulated the triglyceride, HDL and LDL close to those expressed in normal mice. In addition, histological images of the pancreas revealed the restoration in both HG+TE and HG+SRF groups. Simultaneously, the IRS-1 expression in HG+TE group pancreas was restored to its expression in normal mice. These results demonstrate that the TE and SRF of cashew nut testa could ameliorate BG, lipid profile and pancreatic IRS-1 expression and restore the damaged pancreas and islets in hyperglycemic mice

Biocompatible chitosan-functionalized upconverting nanocomposites

Simultaneous integration of photon emission and biocompatibility into nanoparticles is an interesting strategy to develop applications of advanced optical materials. In this work, we present the synthesis of biocompatible optical nanocomposites from the combination of near-infrared luminescent lanthanide nanoparticles and water-soluble chitosan. NaYF4:Yb,Er upconverting nanocrystal guests and water-soluble chitosan hosts are prepared and integrated together into biofunctional optical composites. The control of aqueous dissolution, gelation, assembly, and drying of NaYF4:Yb,Er nanocolloids and chitosan liquids allowed us to design novel optical structures of spongelike aerogels and beadlike microspheres. Well-defined shape and near-infrared response lead upconverting nanocrystals to serve as photon converters to couple with plasmonic gold (Au) nanoparticles. Biocompatible chitosan-stabilized Au/NaYF4:Yb,Er nanocomposites are prepared to show their potential use in biomedicine as we find them exhibiting a half-maximal effective concentration (EC50) of 0.58 mg mL–1 for chitosan-stabilized Au/NaYF4:Yb,Er nanorods versus 0.24 mg mL–1 for chitosan-stabilized NaYF4:Yb,Er after 24 h. As a result of their low cytotoxicity and upconverting response, these novel materials hold promise to be interesting for biomedicine, analytical sensing, and other applications

Some results of research and forecasting of groundwater salinization in the coastal zone of Soc Trang province

In recent years, the situation of salinity intrusion is very complicated and becomes more serious in the coastal area of Soc Trang province. In this research, SEAWAT modified water density flow model was used to forecast the salinity intrusion for Holocene aquifer (qh) and upper Pleistocene aquifer (qp3) according to the water use planning scenario. The results show that the impact of groundwater extraction process increases the TDS content in the aquifer, the salt water/fresh water areas change over time, the trend of salinity change increases. In Holocene aquifer, salt water area is relatively large and the TDS concentration increases towards the sea, however, fresh water area changes inconsiderably: In 2015 accounting for 17.42% and by 2030 accounting for 17.77% of aquifer area. In upper Pleistocene aquifer, the fresh water area declines significantly: In 2015 accounting for 9.35% and by 2030 only accounting for 7.53% of aquifer area

Study Structure and Properties of Nanocomposite Material Based on Unsaturated Polyester with Clay Modified by Poly(ethylene oxide)

In recent years, polymer clay nanocomposites have been attracting considerable interests in polymers science because of their advantages. There are many scientists who researched about this kind of material and demonstrated that when polymer matrix was added to little weight of clay, properties were enhanced considerably. Because clay is a hydrophilic substance so it is difficult to use as filler in polymer matrix having hydrophobic nature, so clay needs to be modified to become compatible with polymer. In this study, poly(ethylene oxide) was used as a new modifier for clay to replace some traditional ionic surfactants such as primary, secondary, tertiary, and quaternary alkyl ammonium or alkylphosphonium cations having the following disadvantages: disintegrate at high temperature, catalyze polymer degradation, and make nanoproducts colorific, and so forth. In order to evaluate modifying effect of poly(ethylene oxide), modified clay products were characterize d by X-ray spectrum. Then organoclay was used to prepare nanocomposite based on unsaturated polyester. Morphology and properties of nanocomposites were measure d by X-ray diffraction, transmission electron microscopy, tensile strength, and thermal stability. The results showed that clay galleries changed to intercalated state in the nanocomposites. Properties of nanocomposites were improved a lot when the loading of the organoclay was used at 1 phr

Quantifying antimicrobial access and usage for paediatric diarrhoeal disease in an urban community setting in Asia.

OBJECTIVES: Antimicrobial-resistant infections are a major global health issue. Ease of antimicrobial access in developing countries is proposed to be a key driver of the antimicrobial resistance (AMR) epidemic despite a lack of community antimicrobial usage data. METHODS: Using a mixed-methods approach (geospatial mapping, simulated clients, healthcare utilization, longitudinal cohort) we assessed antimicrobial access in the community and quantified antimicrobial usage for childhood diarrhoea in an urban Vietnamese setting. RESULTS: The study area had a pharmacy density of 15.7 pharmacies/km2 (a pharmacy for every 1316 people). Using a simulated client method at pharmacies within the area, we found that 8% (3/37) and 22% (8/37) of outlets sold antimicrobials for paediatric watery and mucoid diarrhoea, respectively. However, despite ease of pharmacy access, the majority of caregivers would choose to take their child to a healthcare facility, with 81% (319/396) and 88% (347/396) of responders selecting a specialized hospital as one of their top three preferences when seeking treatment for watery and mucoid diarrhoea, respectively. We calculated that at least 19% (2688/14427) of diarrhoea episodes in those aged 1 to <5 years would receive an antimicrobial annually; however, antimicrobial usage was almost 10 times greater in hospitals than in the community. CONCLUSIONS: Our data question the impact of community antimicrobial usage on AMR and highlight the need for better education and guidelines for all professionals with the authority to prescribe antimicrobials

Лексические средства связности в речи телеведущего в жанре интерактивной белорусскоязычной телебеседы

Материалы XII Междунар. науч. конф. студентов, магистрантов, аспирантов и молодых ученых, Гомель, 16–17 мая 2019 г

CHITIN LIQUID CRYSTAL- DERIVED SPONGE- LIKE AEROGEL

Abstract: Chitin nanocrystals in anisotropic liquid crystals have been used as a colloidal precursor to fabricate hydrogels and aerogels. Native chitin nanofibrils are deacetylated and hydrolyzed to generate rod-shaped chitin nanocrystals that are dispersible in water to form colloidal aqueous suspensions. Chitin nanocolloids self-organize into anisotropic liquid crystals that can solidify into layered nematic films. Chitin liquid crystals are hydrothermally gelatinized with formaldehyde crosslinkers to form homogeneous chitin hydrogels. The removal of water in the hydrogels by freeze-drying recovers ultralight chitin sponge-like aerogels with morphological retention of layered nematic chitin structure. These biocompatible chitin aerogels hold promise for developing advanced functional materials such as fabrics for antibacterial bandages and tissue engineering and hydrophobic absorbents for oil/water separation. Potentially, chitin nanocrystals assembled in the aerogels may be functionalized into hydrophobic sponges for oil/water separation or carbonized into nitrogen-doped carbon foams for supercapacitors

Evaluating the efficiency of Vietnam banks using data envelopment analysis

Efficiency is a topic of great interest because its applications are diverse and rich. It is applied greatly in all scientific disciplines, especially accounting for a very large proportion in economics, finance and accounting. The main objective in this paper is to analyze the effectiveness of banks in Vietnam. In order to investigate this issue, there are several implements to examine bank effectiveness where the data envelopment analysis (DEA) method is widely used. This paper presents details of the DEA method. Using the data collected from banks in Vietnam for the period 2014-2017, the approach is executed to investigate issues of technical efficiency, resource analysis and business efficiency of banks in Vietnam

Optimization of an in vitro bioassay for human pdgf (platelet-derived growth factor)

Platelet-derived growth factor (PDGF) is a major mitogen of many messenchymal original cells. With promising potential, PDGF has been considered as an emerging recombinant product which is targeted to pharmaceutical applications. Testing biological activity is an essential step in PDGF manufacturing. There are in vitro assay which based on PDGF function of stimulating fibrolast cell proliferation and in vivo assay which shows PDGF capability in healing wound. The former assay serves many advantages, such as saving time, expenditure, and scale of experiments. Several PDGF in vitro assays have been used in some scientific publications. While the PDGF manufacturing asks for a stable, specific and authentic bioassay, those published bioassays differ from each others in some parameters such as: synchronization methods, PDGF-treating time, etc. To provide scientific base for selecting and using an in vitro bioassay in PDGF manufacturing in Vietnam,  this paper presented the results of evaluation and optimization of PDGF in vitro bioassay. The results demontrated a stable and sensitive PDGF bioassay (%CV<15%) in which 5×103 initial seeding cells per well was used without sychronization, following by 36 hours PDGF-treated in FBS-free medium