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In this work we investigated the nonlinear vibration of nanocomposite multilayer perovskite solar cell (NMPSC) subjected to the combination of mechanical and thermal loadings. The model of organic solar cell is assumed to consist seven functional layers: Au, Spiro-OMeTAD, PEDOT:PSS, Graphene oxide, MAPbI3, TiO­2 and IOT, and glass substrate. The governing equations are established basing on the classical plate theory taking into account the effect of elastic foundations and initial imperfection. Four edges of the NMPSC are assumed to be supported immovably in a transverse plane. The relationship between deflection amplitude and time as well as the expression of natural frequency of NMPSC are obtained by using the Galerkin and Runge – Kutta methods. The numerical results showed that the nonlinear dynamic response and the natural frequency of NMPSC have been strongly influenced by the geometrical and material parameters, initial imperfection, temperature increment and elastic foundations. Keywords: Perovskite solar cell; nonlinear vibration; elastic foundations; initial imperfection; thermal environment

Repeated column chromatography resulted in the isolation of two new glycosides, miliusides A-B (

Từ đầu năm 2009 Bệnh viện Trung ương Huế đã được trang bị máy CT-64 lát cắt, chúng tôi đã phát hiện nhiều trường hợp tim bẩm sinh phức tạp như tứ chứng Fallot, thất phải hai đường ra, tuần hoàn bàng hệ chủ-phổi phức tạp, bất sản động mạch phổi có kèm thông liên thất, thất trái độc nhất, hẹp eo động mạch chủ, đứt đoạn động mạch chủ, phình động mạch vành, còn ống động mạch…Hầu hết các trường hợp được phẫu thuật đều có kết quả phù hợp với chẩn đoán. Với độ phân giải từng phần cao và tái tạo hình ảnh 3 chiều, CT-64 lát cắt tim mạch thể hiện rất hiệu quả các cấu trúc giải phẫu và mối tương quan giữa chúng, ngay cả ở các trẻ nhỏ. CT-64 lát cắt tim mạch đặc biệt hữu ích để khảo sát hình ảnh của các vùng mà siêu âm tim không thể nhìn thấy rõ như các mạch máu lớn. CT-64 lát cắt tim mạch là phương pháp khám xét nhanh và không xâm nhập, có thể chẩn đoán chính xác các bệnh tim bẩm sinh, khắc phục các hạn chế của siêu âm tim như cửa sổ âm khó khảo sát và cung cấp các thông tin cần thiết tổng thể cho phẫu thuật.

Suy tĩnh mạch mạn tính chi dưới là bệnh lý khá thường gặp, chiếm khoảng 40,5% người trên 50 tuổi, nữ giới nhiều gấp 4,25 lần so với nam giới [Error! Reference source not found.]. Tổn thương có thể gặp ở tĩnh mạch nông, tĩnh xuyên, tĩnh mạch sâu hoặc ở cả 3 hệ tĩnh mạch của chi dưới [0]. Riêng về bệnh lý tĩnh mạch nông, một cách tổng quát, ta có thể phân thành 3 nhóm sau: nhóm suy tĩnh mạch mạn tính, nhóm giãn tĩnh mạch, nhóm viêm tắc tĩnh mạch. Điều trị suy tĩnh mạch chi dưới nói chung và suy – giãn tĩnh mạch nông nói riêng được phân làm 2 mảng chính: nội khoa và ngoại khoa. Điều trị ngoại khoa chủ yếu vẫn là phẫu thuật. Từ các thập niên 80 – 90 của thế kỉ 20, các phương pháp can thiệp nội mạch trong điều trị suy – giãn tĩnh mạch nông chi dưới lần lượt được thực hiện và đã mở ra một bước tiến mới trong điều trị bệnh lý suy tĩnh mạch chi dưới [0, 0, 0, 0, 16] .

Lower limb chronic venous insufficiency is a commonly seen disease which accounted for 40.5% of people over the age of 50 years old with females having 4.25 higher prevalence compared with males [23]. The lesions could be observed in superficial, perforating, deep veins or all three venous systems in the lower extremities [2]. Superficial veins in particular could be classified in 3 groups: chronic venous insufficiency, varicose veins, and thrombophlebitis. The treatment options of lower limb chronic venous insufficiency in general and chronic venous insufficiency – varicose veins are grouped in two major categories: medication/intervention and surgery. Since 1980s-1990s, endovascular interventions for the treatment of superficial venous insufficiency – varicose veins were introduced and were the new advancement in the treatment of lower limb venous insufficiency disorders [3, 7, 11, 12, 16] .

Fifteen yeast strains isolated from maprang (Bouea macrophylla Griffith) were characterised using standard microbiological procedures. The species were identified belonging to three genera Saccharomyces, Hanseniaspora and Pichia and their abilities for wine production were tested by analysing the alcohol produced and remaining sugar. The best biochemically active strain was used along with commercial yeast (S. cerevisiae) to produce wine from maprang juice. Fermenting activity of isolated yeasts was higher than commercial yeast. The isolated yeast strain namely 3.5B and 5.5A showed the best fermenting activity such as fast fermentation by Durham test and highest alcohol percentage (11.5 and 11.83% v/v). Based on the 28S rRNA sequences, yeast strain 5.5A and 3.5B showed 99% similarity to S. cerevisiae (KP723678.1 and KF728774.1, respectively). Using isolated yeast strain 5.5A for wine fermentation at pH 4.0, total soluble solid content 24% and inoculated with yeast density of 107 cells/mL, the alcohol content produced was 14.5% v/v and the wine had favorable color and flavor. Our work constitutes a foundation for strain selection for future applications as starter cultures in fruit wine fermentations. This work is the first ever on yeast diversity from maprang which is the special fruit of Vinh Long province, Vietnam.

This paper focuses on the influence of CNTs, porosity, mechanical and thermal loading on the vibration and dynamic response of the sandwich functionally graded carbon nanotube-reinforced composite ...

Single Point Incremental Forming (SPIF) is really a new technology of forming metal sheet nowadays and in recent decades. Although it was invented in, 1967 by Lezak, an American inventor, but the applications of the innovative technology were broad from 1990 because of the advance of controlling technology. This technology is especially adapted to small batch, unique or single productions. There are many forming parameters that influence to the formability of the metal sheet workpiece such as diameter of tool, the revolution per minute of the tool tip, the vertical feed rate after each orbit, the velocity of tool in horizontal plane…. Among of them, in our own experiences, we recognize that in almost all cases, the revolution per minute of the forming tool when forming ferric material sheet such as mild steel, stainless steel, hard steels… should be as small as possible to get the biggest ability of deformation of the workpiece sheet to get rid of failure on the lateral edge of the sheet. The tangential velocity of forming point on the spherical tool tip should be selected to attain the situation of rolling but no sliding of the surface of the spherical tool on the one of the sheet material. The paper recommends a new version of a forming tool in which the tip of the tool is a very hard ball (such as the quenched ball in a ball bearing) that is freely rotate by the friction to modify the contact point on the spherical surface of the tool to avoid the abrading and keep the spherical shape and the situation of rotating but no sliding on the surface of the workpiece sheet as mentioned above. The manufacture of the innovative forming tool is performed and then empirical processes verified it. The models formed by the typical tool are better in comparison with the ones of normal forming tool.

A new rhamnofolane-type diterpenoid (1) and a new phenolic derivative (2), together with eleven known compounds, were isolated from the leaves of E. cochinchinensis Lour. The chemical structures of these compounds were elucidated based on extensive spectroscopic analysis, including HR-QTOF-MS and NMR, and comparison with reported data. The inhibitory effects of compounds 1–13 on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW264.7 cells were evaluated. As the obtained results, compound 9 showed a moderate inhibitory effects on NO production activity with an IC50 of 6.17 ± 0.25 µM, relative to that of the positive control cardamonin.

The total mean ∑ $$15\overline{\text{PAHs}}$$ in samples were from 75.3 to 387.0 ng/g dry weight (d.w) and showed high value in black dry tea, followed by herbal, oolong, and green tea. The mean ∑ $$\overline{\text{PAH4}}$$ (a combination of benz[a]anthracene, chrysene, benzo[b]fluoranthene, and benzo[a]pyrene) values were 54.3 ng/g, 16.4 ng/g, 14.2 ng/g, and 6.6 ng/g for black, herbal, green, and oolong teas, respectively. Concentration for benzo[a]pyrene (BaP) was from 0.4 to 35.8 ng/g, and the BaP equivalent concentration values ranged from 0.3 to 48.1 ng/g. There was only 1 black tea sample that BaP concentration exceeded the maximum level according to European Union (EU) standards. Tea samples marketed in Vietnam showed insignificant difference with the samples from other origins by same analytical method. Black teas showed high PAHs contents in dry tea samples but the released percentage of sum of PAHs from tea-to-tea infusion was lower than that in other tea type samples. The released percentages of PAH4 from tea-to-tea infusion were 40.7, 15.4, and 1.9 for green, herbal, and black tea. High temperature in black tea manufacturing processes might reduce essential oil content in tea that might effect on the PAHs partially release into the infusion. Indeed, based on EU regulations, we may conclude that tea consumers are safe in risk of exposure to PAHs obtained from teas.

In this study, a series of fourteen Cu (II), Zn (II), Ni (II) and Ag (I) complexes containing bis-benzimidazole derivatives were successfully designed and synthesized from 2-(1H-benzimidazole-2-yl)-phenol derivatives and corresponding metal salt solutions. The compound structures were identified by FT-IR, 1H-NMR, powder X-ray diffraction and ESI-MS analyses, and the presence of the metal in the complexes was confirmed by ultraviolet-visible spectroscopy and ICP optical emission spectrometry. Electronic structure calculations were also carried out to describe the detailed structures in addition to the electronic absorption spectra of the ligands. The cytotoxic activity of the complexes was evaluated against three human cancer cell lines: lung (A549), breast (MDA-MB-231) and prostate (PC3) cancer cells. All complexes inhibited anti-proliferative cancer cells better than free ligands, especially Zn (II) and Ag (I) complexes, which are most sensitive to MDA-MB-231 cells. In addition, showing the growth inhibition of three cancer cell lines with IC50 < 10.4 µM, complexes C1, C3 and C14 could be considered potential multi-targeted anti-cancer agents.

The Annamites mountain range of Southeast Asia which runs along the border of Viet Nam and Laos is an important biodiversity hotspot with high levels of endemism. However, that biodiversity is threatened by unsustainable hunting, and many protected areas across the region have been emptied of their wildlife. To better protect the unique species in the Annamites, it is crucial to have a better understanding of their ecology and distribution. Additionally, basic genetic information is needed to provide conservation stakeholders with essential information to facilitate conservation breeding and counteract the illegal wildlife trade. To date, this baseline information is lacking for many Annamites species. This thesis aims to assess the effectiveness of using non-invasive collection methods, i.e. camera-trap surveys and leech-derived wildlife host DNA, in order to improve and enhance our understanding of ecology, distribution, and genetic diversity of the Annamites terrestrial mammals. In chapter 1, we analysed data from a systematic landscape camera-trap survey using single-species occupancy models to assess the ecology and distribution of two little-known Annamite endemics, the Annamite dark muntjac (Muntiacus rooseveltorum / truongsonensis) and Annamite striped rabbit (Nesolagus timminsi), in multiple protected areas across the Annamites. This chapter provided the first in-depth information on their ecology, as well as distribution patterns at large spatial scales. Most notably, we found that the Annamite dark muntjac was predominantly found at higher elevations, while responses to elevation varied among study areas for the Annamite striped rabbit. We estimated occupancy probabilities for both endemics by using their responses to environmental and anthropogenic influences and used this information to make recommendations for targeted conservation actions. We discuss how the approach we used for these two Annamites endemics can be expanded for other little-known and threatened species in other tropical regions. As is the case with ecology and distribution, very little is known about the genetic diversity of the Annamite striped rabbit and other mammals of the Annamites. This poor understanding is mainly attributed to the lack of a comprehensive DNA sample collection that covers the species’ entire distribution range, which is believed to be a consequence of the low density of mammals or the remoteness of species’ habitat. In order to overcome the difficulties when trying to collect DNA samples from elusive mammals, we applied invertebrate-derived DNA (iDNA) sampling via hematophagous leeches to indirectly obtain genetic materials of their terrestrial host mammals. In chapter 2, leech-derived DNA was used to study the genetic diversity of the Annamite striped rabbit population. By analysing the DNA extracted from leech samples collected at multiple study areas of the central Annamites, we found a genetic variation with five haplotypes among nine obtained sequences. Despite this diversity, we found no clear phylogeographic pattern among the lagomorph’s populations in central Annamites. The findings have direct conservation implications for the species, as local stakeholders are currently establishing a conservation rescue and breeding facility for Annamite endemic species. Thus our results suggested that Annamite striped rabbits from multiple protected areas in central Annamites can be used as founders for the breeding program. In chapter 3, the genetic material of six mammals, which are frequently found in Indochina's illegal wildlife trade, was extracted from leeches collected at six study sites across the Anamites. Species-specific genetic markers were used to obtain DNA fragments that were analysed together with Genbank reference sequences from other parts of the species’ distribution range. Our results showed that invertebrate-derived DNA can be used to fill the sampling gaps and provide genetic reference data that is needed for conservation breeding programmes or to counteract the illegal wildlife trade. Overal, this dissertation provides the first insights in the ecology, distribution, and genetics of rare and threatened species of the Annamites by utilising camera traps and leech-derived DNA as two non-invasive collection methods. This information is essential for improving conservation efforts of local stakeholders and managers, especially for the Annamite endemics. Results in this dissertation also show the effectiveness of both non-invasive methods for studying terrestrial mammals at a landscape level. By expanding the application of these methods to other protected areas across the Annamites, we will further our understanding of ecology, distribution, and genetics of Annamite endemics. With such landscape-scale surveys, we are able to provide stakeholders with an overview of the current status of wildlife in the Annamites which supports efforts to protect these secretive species from illegal hunting and thus their extinction.

Thin films were deposited on SUS440 stainless steel samples by arc plasma evaporation at substrate bias voltages of 10–100 V. X-ray diffraction, optical microscopy, field emission scanning electron microscopy, energy dispersive spectroscopy, microhardness test, and electrochemical test were used to investigate the morphology and properties of the thin films. Particularly, the thin films were composed of chromium nitride (CrN, phases of CrN + Cr) and 0.76 mm thick. They were deposited with microdroplets on the samples. The surface hardness of these films reached the highest value of 1492 HV at the bias of 20 V. As the bias voltage increased, the adhesion of the CrN thin films decreased. The excessively high bias voltage of 100 V led to the delamination of the CrN thin films. The electrochemical test demonstrated that the corrosion resistance in the 3% NaCl solution of CrN coating can be improved.

The rise in Plasmodium falciparum resistance to dihydroartemisinin-piperaquine in Vietnam justifies the need to evaluate alternative artemisinin-based combination therapies. Between July 2018 and October 2019, a single-arm trial of pyronaridine-artesunate (Pyramax, PA) was conducted in Dak Nong province, Vietnam. PA (3-day course) was administered to adults and children infected with P. falciparum. PA was well tolerated by the participants. The proportion of patients with Day 42 PCR-corrected adequate clinical and parasitological response was 95.2% (95% confidence interval [CI], 82.3 to 98.8, n = 40/42) for treating falciparum malaria. The median parasite clearance half-life was 6.7 h (range, 2.6 to 11.9) and the median parasite clearance time was 72 h (range, 12 to 132) with 44.9% (22/49) of patients having positive blood films at 72 h. The two patients that recrudesced had comparable Day 7 blood pyronaridine concentrations (39.5 and 39.0 ng/ml) to the 40 patients who did not recrudesce (median 43.4 ng/ml, 95% CI, 35.1 to 54.9). Ring-stage and piperaquine survival assays revealed that of the 29 P. falciparum isolates collected from the patients before PA treatment, 22 (75.9%) had reduced susceptibility to artemisinins and 17 (58.6%) were resistant to piperaquine. Genotyping confirmed that 92.0% (46/50) of falciparum patients were infected with parasites bearing the Pfkelch13 C580Y mutation associated with artemisinin resistance. Of these, 56.0% (28/50) of the isolates also had multiple copies of the plasmepsin 2/3 genes responsible for piperaquine resistance. Overall, PA was effective in treating P. falciparum in the Central Highlands of Vietnam. (This study has been registered at AustralianClinicalTrials.gov.au under trial ID ACTRN12618001429246.).

Background Malaria elimination by 2030 is an aim of many countries in the Greater Mekong Sub-region, including Vietnam. However, to achieve this goal and accelerate towards malaria elimination, countries need to determine the extent and prevalence of asymptomatic malaria as a potential reservoir for malaria transmission and the intensity of malaria transmission. The purpose of this study was to determine the prevalence of asymptomatic malaria and seropositivity rate in several districts of Gia Lai province in the Central Highlands of Vietnam. Methods A cross-sectional survey of asymptomatic malaria and serological testing was conducted in 3283 people living at 14 communes across seven districts in Gia Lai province in December 2016 to January 2017. Finger prick capillary blood samples were tested for malaria using rapid diagnostic testing and polymerase chain reaction (PCR), as well as detecting antibodies against 3 Plasmodium falciparum and 4 Plasmodium vivax antigens by indirect enzyme-linked immunosorbent assay (ELISA). Age-seroprevalence curves were fitted using reverse catalytic models with maximum likelihood. Results The study population was predominantly male (65.9%, 2165/3283), adults (88.7%, 2911/3283) and of a minority ethnicity (72.2%, 2371/3283), with most participants being farmers and outdoor government workers (90.2%, 2960/3283). Using a small volume of blood (≈ 10 µL) the PCR assay revealed that 1.74% (57/3283) of the participants had asymptomatic malaria (P. falciparum 1.07%, P. vivax 0.40%, Plasmodium malariae 0.15% and mixed infections 0.12%). In contrast, the annual malaria prevalence rates for clinical malaria in the communities where the participants lived were 0.12% (108/90,395) in 2016 and 0.22% (201/93,184) in 2017. Seropositivity for at least one P. falciparum or one P. vivax antigen was 38.5% (1257/3262) and 31.1% (1022/3282), respectively. Age-dependent trends in the proportion of seropositive individuals in five of the districts discriminated the three districts with sustained low malaria prevalence from the two districts with higher transmission. Conclusions Asymptomatic Plasmodium carriers were found to be substantially more prevalent than clinical cases in seven districts of Gia Lai province, and a third of the population had serological evidence of previous malaria exposure. The findings add knowledge on the extent of asymptomatic malaria and transmission for developing malaria elimination strategies for Vietnam.

The Northeastern coastal zone of Vietnam possesses high biodiversity and rich ecosystems like coral reefs, seagrasses, beaches and mangroves. It also includes the Ha Long Bay Natural Heritage site (UNESCO 1994) and the Cat Ba Biosphere Reserve (MAB/UNESCO 2004) as well as hosts the Economic Development Triangle (Hai Phong−Ha Noi–Quang Ninh) established by the Government of Vietnam. As one of the coastal ecosystems, sandy beach ecosystems attracted more attention during recent decades because of their essential role for human welfare and in environmental protection. A few studies concentrated on sustainable management of sandy beach based on environmental and ecological protection and enhance the beach quality for recreational use. The DPSIR (Driving force Pressure State Impact Response) framework describes the logical interaction among systems and finds out the cause and consequence of social-economic development activities to the environment and resources. In this study, the DPSIR was applied on the sandy beaches in the Northeastern coast of Vietnam to reveal the main environmental problems on sandy beaches including the decline of the natural landscape around the beaches and the degradation of the environment. It also pointed out that tourism development in association with urbanization and sea reclamation is the main driving forces for environmental degradation of the sandy beaches. Therefore, local authorities of Hai Phong and Quang Ninh should take into account several main responses to policies on inter-province coordination and managerial measures with a wider scope, which integrate socio-economic and physical factors, proximity, accessibility, and neighborhood to manage healthy coastal ecosystems and sandy beaches in particular. An integrated coastal management program for the Northeastern coast of Vietnam needs to be developed and carried out to follow the laws of Vietnam as well as to meet local urgent requirements.