Characterization of carboxymethyl cellulase produced by Trichoderma asperellum

Background: The present study characterized extracellular carboxymethyl cellulase (CMCase), an enzyme catalyzes the hydrolysis of the cellulose, from Trichoderma asperellum PQ34 that was isolated from agricultural cultivation soil in Thua Thien Hue, Vietnam.Methods: CMCase was produced by culturing T. asperellum PQ34 on Czapek-Dox medium supplemented with carboxymethyl cellulose (CMC) at 28ºC for 96 h at a shaking speed of 150 rpm. Enzyme activity was spectrophotometerically determined with CMC used as a substrate and the absorbance was measured at 540 nm. The molecular weight of CMCase was determined by zymogram based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with 0.2% CMC.Results: CMCase achieved the highest activity after 4 days of culture with the optimal pH and temperature at 4 and 55°C. The enzyme maintains pH and thermal stability in the range of 4-5 and 10-40°C and the relative activity of both is more than 90%. The presence of metal ions at 5 mM such as Ca2+, Al3+, or Co2+ increased the enzyme activity up to 133%, 124%, and 217%, respectively. CMCase was stable with 1 mM ethylenediaminetetraacetic acid and 1 M urea, but inhibited by 5% sodium dodecyl sulfate (SDS) and 5% Triton-X100. Zymographic analysis showed that CMCase from T. asperellum PQ34 consists of two enzymes with a molecular weight of about 31 and 66 kDa.Conclusion: CMCases from T. asperellum PQ34 exhibited characteristics of an acidic and thermostable enzyme. The interaction of Co2+ and CMCase resulted in a significant increase in enzyme activity, however they were strongly inhibited by 5% SDS.Keywords: Carboxymethyl cellulase; Cellulase; Endo-β-1,4-glucanase, Trichoderma asperellu

Energy harvesting over Rician fading channel: A performance analysis for half-duplex bidirectional sensor networks under hardware impairments

In this paper, a rigorous analysis of the performance of time-switching energy harvesting strategy that is applied for a half-duplex bidirectional wireless sensor network with intermediate relay over a Rician fading channel is presented to provide the exact-form expressions of the outage probability, achievable throughput and the symbol-error-rate (SER) of the system under the hardware impairment condition. Using the proposed probabilistic models for wireless channels between mobile nodes as well as for the hardware noises, we derive the outage probability of the system, and then the throughput and SER can be obtained as a result. Both exact analysis and asymptotic analysis at high signal-power-to-noise-ratio regime are provided. Monte Carlo simulation is also conducted to verify the analysis. This work confirms the effectiveness of energy harvesting applied in wireless sensor networks over a Rician fading channel, and can provide an insightful understanding about the effect of various parameters on the system performance.Web of Science186art. no. 1781

Two-way half duplex decode and forward relaying network with hardware impairment over Rician fading channel: system performance analysis

In this paper, the system performance analysis of a two-way decode and forward (DF) relaying network over the Rician fading environment under hardware impairment effect is proposed, analyzed and demonstrated. In this analysis, the analytical mathematical expressions of the achievable throughput, the outage probability, and ergodic capacity were proposed, analyzed and demonstrated. After that, the effect of various system parameters on the system performance is deeply studied with closed-form expressions for the system performance. Finally, the analytical results are also demonstrated by Monte-Carlo simulation in comparison with the closed-form expressions. The numerical results demonstrated and convinced the effect of the system parameters on the system performance of the two-way DF relaying network. The results show that the analytical mathematical and simulated results match for all possible parameter values.Web of Science242787

Effect of the green-emitting CaF2:Ce3+,Tb3+ phosphor particles’ size on color rendering index and color quality scale of the in-cup packaging multichip white LEDs

In this paper, we investigate the effect of the green-emitting CaF2:Ce (3+), Tb (3+) phosphor particle's size on the color rendering index (CRI) and the color quality scale (CQS) of the in-cup packaging multichip white LEDs (MCW-LEDs). For this purpose, 7000K and 8500K in-cup packaging MCW-LEDs is simulated by the commercial software Light Tools. Moreover, scattering process in the phosphor layers is investigated by using Mie Theory with Mat Lab software. Finally, the research results show that the green-emitting CaF2: Ce (3+), Tb (3+) phosphor's size crucially influences on the CRI and CQS. From that point of view, CaF2: Ce (3+), Tb (3+) can be proposed as a potential practical direction for manufacturing the in-cup packaging phosphor WLEDs.Web of Science13235134

UNDERSTANDING THE STATUS AND CHALLENGES OF MANGROVE CONSERVATION IN CENTRAL VIETNAM: CASE STUDY IN DUY XUYEN DISTRICT, QUANG NAM PROVINCE

Abstract: While mangrove forests support large surrounding populations and diverse economic activities, mangrove areas in Central Vietnam are decreasing. This study, thereforce, aims to understand the current status and threats facing mangrove conservation and development. A survey of 52 respondents was conducted in Duy Xuyen district, the largest area of mangrove forests of Quang Nam province. The results show that 17 mangrove species belong to 11 families, in which 8 significant species and 9 minor species were found in this site. The distribution of species was uneven with dominated by Nipah palms (Nypafruticans Wurmb). Although the mangrove species had several useful functions including protection against wind, wave break and serving tourism development, mangrove areas have been decreasing from 26.39ha to 18.22ha during period of 1999-2018. In which, 67.3% of respondents argued that the conversion of mangroves to aquaculture is one of the main causes of mangrove loss. The study also provided some suggestions related to a long-term development strategy for both government and local community, especially who are directly involving in the mangrove for their livelihoods.Keywords: Central Vietnam, development strategy, mangrove forests, livelihood

Long-Term Improvement in Precautions for Flood Risk Mitigation: A Case Study in the Low-Lying Area of Central Vietnam

Local actors appear as inseparable components of the integrated flood risk mitigation strategy in Vietnam. Recognizing this fact, this study examined the long-term improvement in precautions taken by commune authorities and households between two major floods in 1999 and 2017 by applying both quantitative and qualitative methods. Two flood-prone villages were selected for a survey; one in a rural area and the other in a suburban area of Thua Thien Hue Province, central Vietnam. The findings indicate that most villagers doubted the structural works' efficacy and were dissatisfied with the current efforts of local authorities. Households' self-preparation thus became the decisive factor in mitigating risk. While most households have paid greater attention to flood precautions in 2017, others seem to be lagging. Poverty-related barriers were the root causes restraining households in both rural and suburban villages. The suburban riverine residents were further identified as vulnerable by their limitations in upgrading structural measures, which was ascribed to the inconsistency in the ancient town's preservation policy. This multidimensional comparison, in terms of vulnerability, emphasized the importance of space-function links in the suburb and the contradictions of different policy initiatives, such as landscape rehabilitation, disaster prevention, and livelihood maintenance

ẢNH HƯỞNG CỦA MỘT SỐ YẾU TỐ CANH TÁC ĐẾN SINH TRƯỞNG VÀ NĂNG SUẤT CỦA CÂY RAU MÁ (Centella asiatica (L.) Urban) NUÔI CẤY MÔ TẠI XÃ QUẢNG THỌ, TỈNH THỪA THIÊN HUẾ

Quang Tho commune is the locality with the largest area of Centella growing in Thua Thien Hue province, with about 70 hectares, of which 52 hectares are produced according to the Vietgap standard. This study investigated the morphological, growth, and yield characteristics of in vitro Centella in Quang Tho commune. The results showed that the growth ability of in vitro origin seedlings was not significantly different from that of natural cuttings or seeds; they had smaller and higher uniform leaves. The in vitro centella shows the best results of leaf morphology, growth, leaf spot disease reduction, and yield when planted in the spring (from 10 to 20/2) with an average planting density (25 plants/m2). The yield reached 6.13 tons/ha with a low disease rate (12.01% after 14 days). Based on the total yield, the suitable duration to harvest is 25-28 days/time (total yield reaches 2.10 kg/m2). Developing a process for growing in vitro centella culture helps provide: Uniform, Disease-free seedlings for planting and helping increase Centella's economic value.Xã Quảng Thọ là địa phương có diện tích trồng rau má lớn nhất trên địa bàn tỉnh Thừa Thiên Huế với diện tích khoảng 70 ha, trong đó có 52 ha rau má được sản xuất theo quy trình Vietgap. Trong nghiên cứu này, chúng tôi đã khảo sát các đặc điểm hình thái, sinh trưởng và năng suất của cây rau má có nguồn gốc nuôi cấy mô. Kết quả nghiên cứu cho thấy khả năng sinh trưởng của cây rau má nuôi cấy mô không có sự khác biệt quá lớn so với cây rau má giâm hom tự nhiên hay từ hạt, cây có lá nhỏ hơn và độ đồng đều cao hơn. Cây rau má nuôi cấy mô có các chỉ tiêu về hình thái lá, sinh trưởng, bệnh đốm lá và năng suất tốt nhất khi được trồng vào vụ xuân (khoảng 10-20/2) với mật độ trồng trung bình (25 cây/m2), năng suất đạt 6,13 tấn/ha và có tỷ lệ bệnh đốm lá thấp (12,01% sau 14 ngày theo dõi). Khoảng cách giữa các lần thu hoạch của cây rau má nuôi cấy mô là 25-28 ngày cho năng suất cao nhất (tổng năng suất đạt 2,10 kg/m2). Từ các kết quả thu được, nghiên cứu đã góp phần xây dựng quy trình trồng cây rau má có nguồn gốc nuôi cấy mô để sản xuất rau má theo hướng hữu cơ, giúp tăng giá trị kinh tế của loại cây này

System Performance Analysis of Half-Duplex Relay Network over Rician Fading Channel

In this paper, the system performance of an amplify-and-forward (AF) relaying network over Rician Fading Channel is proposed, analyzed and demonstrated. For details this analysis, the energy and information are transferred from the source to the relay nodes by two methods: 1) time switching protocol and 2) power splitting protocol. Firstly, due to the constraint of the wireless energy harvesting at the relay node, the analytical mathematical expressions of the achievable throughput and the outage probability of both schemes were proposed and demonstrated. After that, the effect of various system parameters on the system performance is rigorously studied with closed-form expressions for the system performance. Finally, the analytical results are also demonstrated by Monte-Carlo simulation in comparison with the closed-form expressions. The numerical results demonstrated the effect of various system parameters, such as energy harvesting time, power splitting ratio, source transmission to noise power, and the threshold value, on the system performance of AF wireless relay nodes. The results show that the analytical mathematical and simulated results match for all possible parameter values for both schemes

ISOLATION AND STRUCTURAL CHARACTERIZATION OF TWO SAPONINS FROM THE ROOTS OF Sansevieria trifasciata ‘Laurentii’

Sansevieria is a genus consisting of about 60 species natively distributed in tropical and subtropical areas. Many Sansevieria species are used for ornamental purposes or in traditional medicine to treat human diseases. Sansevieria trifasciata ‘Laurentii,’ commonly known as snake plant, is an evergreen perennial plant used in traditional medicine. The phytochemical investigation of the roots of S. trifasciata ‘Laurentii’ resulted in the isolation and structural characterization of two previously reported saponins: (24S,25R)-1b-[(β-D-fucopyranosyl)oxy]-3b-hydroxyspirost-5-en-24-yl β-D-glucopyranoside (1) and 26-[(β-D-glucopyranosyl)oxy]-3β,22α-dihydroxyfurosta-5,25(27)-dien-1β-yl-O-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranoside (2) by analysis of their 1D and 2D NMR spectra and HR-ESI-MS, together with the comparison to data published in the literature

Utilizing polydispersity in composite fibrous based sound absorbing materials

The distribution of fiber diameters plays a crucial role in the transport and sound absorbing properties of a three-dimensional random fibrous (3D-RF) composites. Conventionally, volume-weighted averaging of fiber diameters has been utilized as an appropriate microstructural descriptor to predict the static viscous permeability of 3D-RF composites. However, the long wavelength acoustical properties of a 3D-RF composites are also sensitive to the smallest fibers, this is particularly true in the high-frequency regime. In our recent research, we demonstrated that an inverse volume-weighted averaging of fiber diameters can effectively serve as a complementary microstructural descriptor to capture the high-frequency behavior of polydisperse fibrous media. In the present work, we review the identification of two representative volume elements (RVEs) which relies on the reconstruction of 3D-RF composites having volume-weighted and inverse-volume weighted averaged fiber diameters, respectively in the low-frequency and high frequency regimes. We examine the implication of such a weighting procedure on the transport and sound absorbing properties of polydisperse fibrous media, highlighting their potential advantages. Furthermore, we discuss the challenges associated with this research field. Finally, we provide a brief perspective of the future directions and opportunities for advancing this area of study, aiming to overcome challenges and extend the benefits of employing polydispersity as a new lever for the optimization of 3D-RF composites in sound-absorbing materials.Comment: 10 pages, 7 figure