History and applications of concrete steel composite structure

The composite steel-and-concrete structure is a modern structure, combines the advantages of concrete and steel one. Nowadays, it is widely utilized all over the world but not much in Vietnam. Studying the history of formation and development is very meaningful in understanding and applying this type of structure in practice. This article focuses on presenting the formation and development of the composite structure and, at the same time, introduces the potential and applications of the composite structure to the current construction practice in Vietnam

Enhanced Luminous Efficacy of White LED with Flat Dual-Layer Remote Phosphor Structure

This paper shows the differences in luminous fluxes of two distinguishing dual-layer remote phosphor structures, Flat Dual-Remote Phosphor (FDRP) and Concave Dual-Remote Phosphor (CDRP). The impact of the distance between the two phosphor layers (d_1) and the distance from the phosphor layer to the LED surface (d_2) on the optical properties of the CDRP is also presented. Specifically, when d_1 and d_2 are varied, the scattering and absorption characteristics of the remote phosphor layer change dramatically, which enormously influences the color uniformity and illumination capability of WLEDs. The concentration of YAG:Ce3+ phosphor also needs to be modified so that the correlated color temperature of WLEDs could be maintained at 8500K when d_1 and d_2 are adjusted. In case d_1 = d_2 = 0, the scattering and absorption in the remote phosphor layer are minimal, leading to the infinitesimal color and luminous flux. When d_1 and d_2 get bigger, the scattering surface increases and that the blue and yellow rays are blended becomes more uniform, leading to the minimum white light deviation as well as the lowest luminous flux. According to the studied results, the lumen output can be maximum at 1020lm if d_1 = 0.08mm or d_2 = 0.63mm while the smallest color deviation occurs when d_1 = 0.64mm or d_2 = 1.35mm. Therefore, the researched results will provide further information for choosing the suitable d_1 and d_2 in order to improve the quality of WLEDs

The application of (Y,Gd)BO3:Tb3+ and CaGa2S4:Mn2+ phosphors to remote white light-emitting diodes

The remote phosphor structure is superior to the conformal phosphor and the in-cup phosphor in terms of lighting efficiency; however, managing the color quality of the remote phosphor structure has been a nuisance to the manufacturers. To address this problem, many researches were conducted and the results suggested that using dual-layer phosphor structure and triple-layer phosphor structure could improve the color quality in remote phosphor structures. The purpose of this article is to study which one between the two configurations mentioned above allows multi-chip white LEDs (WLEDs) to reach highest indexes in color rendering index (CRI), color quality scale (CQS), luminous flux (LF), and color uniformity. The color temperature of the WLEDs used for the experiments in this article is 8500 K. The result of this research shows that the triple-layer phosphor configuration has higher CRI, CQS, and LE and also able to reduce color deviation resulting in better color uniformity. This conclusion can be verified by analyzing the scattering features of the phosphor layers using the Mie-theory. Being verifiable increases the reliability of the research result and makes it a valuable reference for producing better quality WLEDs

Enhancing the CRI and lumen output for the 6600 K WLED with convex-dual-layer remote phosphor geometry by applying red-emitting MGSR3SI2O8:EU2+,MN2+ phosphor

The traditional white LED product established with a single chip and a single phosphor results in a low color rendering index (CRI). The upgrade of LED package is comprised of two chips and one phosphor material and gives the higher CRI while keeping high luminous efficiency. Based on previous findings, the research paper performs the application of the two chips and two phosphors to enhance the color tunability of LEDs with different amounts and intensities of the two employed phosphors. Additionally, a color design model is built to serve the purpose of bettering the color fine-tuning of the white-light LED module. The maximum value of the difference between the measured CIE 1931 color coordinates and that of the simulated model is approximately 0.0063 around the 6600 K correlated color temperature (CCT). From the results, this study offers a quick approach to achieve the color fine tuning of a white-light LED module with a high CRI and luminous efficiency

Biological activities of essential oil extracted from leaves of Atalantia sessiflora Guillauminin Vietnam

Introduction: The present study aimed to determine the chemical compositions and bioactivities of the essential oil of Atalantia sessifloraGuillaumin (A. sessiflora), including antibacterial, antimycotic, antitrichomonas, anti-inflammatory and antiviral effects. Methodology: The essential oil from leaves of A. sessiflora was extracted by hydrodistillation using a Clevenger apparatus. Chemical compositions of oil were identified by GC/MS. Antimicrobial and antitrichomonas activity were determined by the microdilution method; anti-inflammatory and antiviral were determined by the MTT method. Results: The average yield of oil was 0.46 ± 0.01% (v/w, dry leaves). A number of 45 constituents were identified by GC/MS. The essential oil comprised four main components. The oil showed antimicrobial activities against Gram-positive strains as Staphylococcus; Gram-negative bacteria such as Klebsiella pneumoniae and Escherichia coli; and finally four Candidaspecies. Enterococcus faecalis and Pseudomonas aeruginosawere least susceptible to the oil of A. sessiflora, as seen in their MIC and MLC values over 16% (v/v). Activity against Trichomonas vaginalis was also undertaken, showing IC50, IC90 and MLC values of 0.016, 0.03 and 0.06% (v/v) respectively, after 48 hours of incubation. The oil of A. sessiflora displayed activity against the nitric oxide generation with the IC50 of 95.94 ± 6.18 μg/mL. The oil was completely ineffective against tested viruses, ssRNA+, ssRNA-, dsRNA, and dsDNA viruses. Conclusions: This is the first yet comprehensive scientific report about the chemical compositions and pharmacological properties of the essential oil of A. sessiflora. Further studies should be done to evaluate the safety and toxicity of A. sessiflora oil

MULTI-CRITERIA DECISION-MAKING FOR ELECTRIC BICYCLE SELECTION

Electric bicycle is a vehicle which is used widely in all the citys and provinces of Vietnam. However, it’s hard to choose “the most suitable” or “the best” type of electric bicycle because each type has different criteria (parameters). To choose out the best option, we need to consider all the alternatives at once. That is called multi-criteria decision-making. This research used three multi-criteria decision-making methods include SAW method, MARCOS method and PSI method to choose from seven bestselling types of electric bicycle on the market in 2022. All the methods which were used chose out the same best electric bicycle type and the same worst bicycle type. And so, among seven types of electric bicycle which include M133 mini, M133 Sport 2022, Aima 133AM, Nijia – PA4, DK 133M, Yadea iGo and Yadea i3, the best type is Aima 133AM, in contrast, Yadea iGo is considered the worst type. Things that need to be done in the folowing researches were proposed in the last part of this paper

ĐẶC ĐIỂM HÌNH THÁI VÀ ĐẶC ĐIỂM VI HỌC CỦA LOÀI BA KÍCH TÍM (Morinda officinalis How.) THU HÁI TẠI TỈNH THỪA THIÊN HUẾ

Morinda officinalis How. is a medicinal plant that has been studied and used for a long time. Previous studies on M. officinalis primarily focused on the source in the northern provinces of Vietnam. This study is the first one on the botanical characteristics, including morphology, anatomy, and powder microscopy of M. officinalis in Thua Thien Hue province. Morphological and microscopic characteristics were determined by comparing the shape and double-staining and observing under a microscope through 10× and 40× objective lenses. The results show the similarities and differences of M. officinalis in Thua Thien Hue and other regions of Vietnam. Particularly, the root of M. officinalis in Thua Thien Hue has a higher percentage of usable parts than other M. officinalis species in northern regions. Furthermore, the results of the study provide scientific data for learning and investigating the morphological and microscopic characteristics of M. officinalis in Thua Thien Hue.Ba kích tím (Morinda officinalis How.) là một loài dược liệu quý được nghiên cứu và sử dụng từ rất lâu đời. Các nghiên cứu về Ba kích tím trước đây chủ yếu tập trung vào nguồn giống thu hái tại các tỉnh phía Bắc của Việt Nam. Nghiên cứu này là công trình đầu tiên về đặc điểm thực vật bao gồm hình thái, vi phẫu và soi bột của cây Ba kích tím được thu hái tại môi trường tự nhiên của tỉnh Thừa Thiên Huế. Đặc điểm hình thái và đặc điểm vi học được nghiên cứu bằng phương pháp so sánh hình thái và nhuộm kép và quan sát dưới kính hiển vi qua vật kính 10× và 40×. Kết quả nghiên cứu cho thấy sự tương đồng và khác biệt chính về đặc điểm thực vật của cây Ba kích tím giữa Thừa Thiên Huế và các vùng miền khác ở Việt Nam. Đặc biệt, rễ củ Ba kích tím tại Thừa Thiên Huế có tỷ lệ bộ phận sử dụng nhiều hơn so với các loài Ba kích tím tại khu vực phía Bắc. Kết quả của bài báo góp phần cung cấp dữ liệu khoa học cho học tập và nghiên cứu về đặc điểm hình thái và vi học của loài Ba kích tím ở Thừa Thiên Huế

A Multi-Center Randomised Controlled Trial of Gatifloxacin versus Azithromycin for the Treatment of Uncomplicated Typhoid Fever in Children and Adults in Vietnam

BACKGROUND: Drug resistant typhoid fever is a major clinical problem globally. Many of the first line antibiotics, including the older generation fluoroquinolones, ciprofloxacin and ofloxacin, are failing. OBJECTIVES: We performed a randomised controlled trial to compare the efficacy and safety of gatifloxacin (10 mg/kg/day) versus azithromycin (20 mg/kg/day) as a once daily oral dose for 7 days for the treatment of uncomplicated typhoid fever in children and adults in Vietnam. METHODS: An open-label multi-centre randomised trial with pre-specified per protocol analysis and intention to treat analysis was conducted. The primary outcome was fever clearance time, the secondary outcome was overall treatment failure (clinical or microbiological failure, development of typhoid fever-related complications, relapse or faecal carriage of S. typhi). PRINCIPAL FINDINGS: We enrolled 358 children and adults with suspected typhoid fever. There was no death in the study. 287 patients had blood culture confirmed typhoid fever, 145 patients received gatifloxacin and 142 patients received azithromycin. The median FCT was 106 hours in both treatment arms (95% Confidence Interval [CI]; 94-118 hours for gatifloxacin versus 88-112 hours for azithromycin), (logrank test p = 0.984, HR [95% CI] = 1.0 [0.80-1.26]). Overall treatment failure occurred in 13/145 (9%) patients in the gatifloxacin group and 13/140 (9.3%) patients in the azithromycin group, (logrank test p = 0.854, HR [95% CI] = 0.93 [0.43-2.0]). 96% (254/263) of the Salmonella enterica serovar Typhi isolates were resistant to nalidixic acid and 58% (153/263) were multidrug resistant. CONCLUSIONS: Both antibiotics showed an excellent efficacy and safety profile. Both gatifloxacin and azithromycin can be recommended for the treatment of typhoid fever particularly in regions with high rates of multidrug and nalidixic acid resistance. The cost of a 7-day treatment course of gatifloxacin is approximately one third of the cost of azithromycin in Vietnam. TRIAL REGISTRATION: Controlled-Trials.com ISRCTN67946944

Safety and efficacy of fluoxetine on functional outcome after acute stroke (AFFINITY): a randomised, double-blind, placebo-controlled trial

Background Trials of fluoxetine for recovery after stroke report conflicting results. The Assessment oF FluoxetINe In sTroke recoverY (AFFINITY) trial aimed to show if daily oral fluoxetine for 6 months after stroke improves functional outcome in an ethnically diverse population. Methods AFFINITY was a randomised, parallel-group, double-blind, placebo-controlled trial done in 43 hospital stroke units in Australia (n=29), New Zealand (four), and Vietnam (ten). Eligible patients were adults (aged ≥18 years) with a clinical diagnosis of acute stroke in the previous 2–15 days, brain imaging consistent with ischaemic or haemorrhagic stroke, and a persisting neurological deficit that produced a modified Rankin Scale (mRS) score of 1 or more. Patients were randomly assigned 1:1 via a web-based system using a minimisation algorithm to once daily, oral fluoxetine 20 mg capsules or matching placebo for 6 months. Patients, carers, investigators, and outcome assessors were masked to the treatment allocation. The primary outcome was functional status, measured by the mRS, at 6 months. The primary analysis was an ordinal logistic regression of the mRS at 6 months, adjusted for minimisation variables. Primary and safety analyses were done according to the patient's treatment allocation. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12611000774921. Findings Between Jan 11, 2013, and June 30, 2019, 1280 patients were recruited in Australia (n=532), New Zealand (n=42), and Vietnam (n=706), of whom 642 were randomly assigned to fluoxetine and 638 were randomly assigned to placebo. Mean duration of trial treatment was 167 days (SD 48·1). At 6 months, mRS data were available in 624 (97%) patients in the fluoxetine group and 632 (99%) in the placebo group. The distribution of mRS categories was similar in the fluoxetine and placebo groups (adjusted common odds ratio 0·94, 95% CI 0·76–1·15; p=0·53). Compared with patients in the placebo group, patients in the fluoxetine group had more falls (20 [3%] vs seven [1%]; p=0·018), bone fractures (19 [3%] vs six [1%]; p=0·014), and epileptic seizures (ten [2%] vs two [<1%]; p=0·038) at 6 months. Interpretation Oral fluoxetine 20 mg daily for 6 months after acute stroke did not improve functional outcome and increased the risk of falls, bone fractures, and epileptic seizures. These results do not support the use of fluoxetine to improve functional outcome after stroke

Thottea aroangensis T. A. Le, D. Dien & Tagane. A. Habit 2021, sp. nov.

Thottea aroangensis T.A. Le, D. Dien & Tagane, sp. nov. (Figs 2 & 3) TYPE: — VIETNAM. Thua Thien Hue province: A Luoi district, A Roang commune, 16°07′39.17″N, 107°24′39.59″E, ± 850 m a.s.l., 18 April 2021, Dien Dinh, Quoc Tuan Doan, Quang Hoa Anh Nguyen, Tuan Anh Le LTA 1101 (holotype VNMN!). Thottea aroangensis is characterized by subshrub habit 70–90 cm tall, inflorescence at base of stem close to ground level, campanulate perianth ca. 2.6 cm long, inside of perianth tube with creamy white patches, obscure perianth lobes very broadly triangular ca. 0.5 cm long, and 20 stamens in 2 whorls, which the combination of characters clearly distinguished it from all the previously known species of the genus. Perennial subshrubs, 70–90 cm tall. Stems erect, scarcely branched, dark green, 0.4–1 cm in diam., terete, glabrous; internode 2.5–15 cm long, node swollen, above nodes constricted. Leaves alternate, distichous; blade elliptic-oblong to obovate, 13–16 × 4–5 cm, slightly curved, laterally not equal, apex acute or mucronate, base obtuse to rounded, slightly oblique, margins entire, adaxial surface green, glabrous, abaxial surface pale green, sparsely pubescent along midrib and veins, midrib prominent on both surfaces, lateral veins 5–6 pairs, prominent on abaxial surface; petioles 0.8–1 cm long, glabrous. Inflorescences 1–2 per plant, racemose, at base of stem close to ground level, axils of fallen leaves, up to 8-flowered; peduncle not branched, 6–11 mm long, 2–3 mm in diam., bracts ovate, elliptic-lanceolate, lanceolate or obovate, 5 × 2–4 mm, venation obvious when young, dark purple, pubescent, margin entire, apex acute, sometimes bifid. Pedicel and ovary 0.5–1.2 cm long, densely pubescent, 4-ribbed. Perianth campanulate, ca. 2.6 cm long, 2.2 cm in diam., base sub-truncate, obscurely lobed, tube ca. 2.1 cm long, outer surface dark claret, sparsely pubescent, with prominent longitudinal veins, inner surface claret with creamy white patches in upper half, densely villous, margin shallowly 3-lobed, lobes very broadly triangular, 0.5 × 0.4–1.8 cm, apex blunt. Stamens 20 in alternate whorls of 2, upper whorl with 10 stamens, lower whorl with 10, filaments 1–1.5 mm long, glabrous, anthers extrose, positioned at swollen connective apex, oblong, ca. 1 mm long, ca. 0.5 mm wide. Style column cylindric, ca. 1.5 mm long, glabrous, stigmatic lobes 8–9, positioned higher than stamens, ca. 4 mm long, glabrous. Capsules ca. 3 cm long, ca. 3.5 mm in diam., dark green to dark purple, curved, 4-angled, puberulent. Seeds not seen. Distribution:— Vietnam, known only from the type locality (Fig. 1). Habitat:— Thottea aroangensis was found on alluvial soils of the shady reclined slope in primary broad-leaved evergreen forest at elevation around 850 m a.s.l., where it grows with Aspidistra heterocarpa Aver., Tillich & V.T. Pham var. echinata Aver., Tillich & T.A. Le, Curculigo sp., Dracaena angustifolia Roxb., and Gomphia serrata (Gaertn.) Kanis. Phenology:— Flowering in March to April and fruiting in April to May. Etymology:— The specific epithet is derived from its type locality, A Roang commune, located in A Luoi district, Thua Thien Hue province, central Vietnam. Vernacular name:— Tốt hoa a roàng Preliminary conservation assessment:— Critically Endangered (CR). To date, we found only five individuals in one population of Thottea aroangensis in the type locality. Therefore, the most appropriate initial assessment of the IUCN conservation status for this species is Critically Endangered (CR) under criteria D (IUCN, 2012). The habitat is located within the protected area at district level and well-protected. However, since it grows near the route for tourist, we need to pay special attention for its survival. Note:— In Indochina, three species of Thottea, T. racemosa, T. tomentosa, and T. aff. hainanensis were recorded (Hou 1981, Hô 1999, Phan et al. 2009, Tagane et al. 2017). Thottea aroangensis is easily distinguished from T. racemosa and T. aff. hainanensis by its inflorescence at base of stem close to ground level (vs. at the upper part of stem, in the axils of foliage leaves) and from T. tomentosa by taller habit 70–90 cm tall (vs. 10–50 cm tall), abaxial surface of lamina sparsely pubescent along midrib and veins (vs. tomentose), and longer perianth ca. 2.6 cm long (vs. 0.7–1.2 cm long). Thottea aroangensis is similar to T. becarrii Hou (1981: 315) of Sumatra in having inflorescence at base of stems and obscurely lobed perianth, but differs in having smaller lamina (13–16 × 4–5 cm in T. aroangensis vs. 19.5–25 × 9.5–15 cm in T. beccarrii), shorter pedicle and ovary (5–12 mm long vs. 15–17.5 mm long), larger campanulate perianth ca. 2.6 cm long (vs. perianth cupular, 1.2–1.5 cm long).Published as part of Le, Tuan Anh, Dinh, Dien, Doan, Quoc Tuan, Nguyen, Quang Hoa Anh & Tagane, Shuichiro, 2021, Thottea aroangensis, a new species of Aristolochiaceae from central Vietnam, pp. 69-74 in Phytotaxa 513 (1) on pages 70-73, DOI: 10.11646/phytotaxa.513.1.5, http://zenodo.org/record/530676