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

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

Chemical components and biological properties from acetone extracts of Conamomum vietnamense

Conamomum vietnamense is an endemic and rare species from Vietnam. The aim of this study is to determine the chemical compositions, antibacterial and antioxidant properties of the acetone extracts obtained from the different organs of this species for the first time. A total of 82 components were identified from the acetone extracts of leaf, flower, and rhizome of C. vietnamense using Gas chromatography–mass spectrometry (GC/MS) technique. Furthermore, the agar disk-diffusion method was also used to determine the antibacterial activity of the C. vietnamense extracts. Accordingly, the leaf extract was found to be effective against eight out of nine bacterial strains while the flower and rhizome extracts displayed activity against four out of nine tested bacteria. In addition, the three organs of C. vietnamense also possessed the high DPPH scavenging properties. The results of this study indicate that C. vietnamense extracts have the potential to be developed into pharmaceutical products in the future

Zero-Knowledge Password Policy Check from Lattices

Passwords are ubiquitous and most commonly used to authenticate users when logging into online services. Using high entropy passwords is critical to prevent unauthorized access and password policies emerged to enforce this requirement on passwords. However, with current methods of password storage, poor practices and server breaches have leaked many passwords to the public. To protect one's sensitive information in case of such events, passwords should be hidden from servers. Verifier-based password authenticated key exchange, proposed by Bellovin and Merrit (IEEE S\&P, 1992), allows authenticated secure channels to be established with a hash of a password (verifier). Unfortunately, this restricts password policies as passwords cannot be checked from their verifier. To address this issue, Kiefer and Manulis (ESORICS 2014) proposed zero-knowledge password policy check (ZKPPC). A ZKPPC protocol allows users to prove in zero knowledge that a hash of the user's password satisfies the password policy required by the server. Unfortunately, their proposal is not quantum resistant with the use of discrete logarithm-based cryptographic tools and there are currently no other viable alternatives. In this work, we construct the first post-quantum ZKPPC using lattice-based tools. To this end, we introduce a new randomised password hashing scheme for ASCII-based passwords and design an accompanying zero-knowledge protocol for policy compliance. Interestingly, our proposal does not follow the framework established by Kiefer and Manulis and offers an alternate construction without homomorphic commitments. Although our protocol is not ready to be used in practice, we think it is an important first step towards a quantum-resistant privacy-preserving password-based authentication and key exchange system

RESEARCH ON BUILDING A COMPOSTING PROCESS OF PEELED SHRIMP SHELLS PRODUCED IN SUPER-INTENSIVE SHRIMP FARMING INTO ORGANIC FERTILIZER BY PROBIOTICS

In this study, the author mixed peeled shrimp shells in intensive shrimp farming and straw with probiotics using the aerobic organic composting process to produce calciumrich organic fertilizer. After 50 days of composting of peeled shrimp shells and straw with BioUSD or Fito-Biomix RR probiotics, the resulting fertilizer was brown-black in color, highly soft, spongy and highly degraded and has a relatively uniform size. Due to the action of microorganisms in Bio-USD probiotics, the nutritional compositions in peeled shrimp shell fertilizer had total nitrogen 4.34%, NH4+-N 269 (mg/kg), total carbon 14.6%, organic matter 51.3%, total calcium 22.0%, and C/N ratio 3.26. Similarly, the nutritional compositions in that fertilizer by FitoBiomix RR probiotics were total nitrogen 4.17%, NH4+-N 329 (mg/kg), total carbon 17.8%, organic matter 53.8%, total calcium 17.8%, and C/N ratio 4.27. Finally, the author evaluated the quality of the fertilizers with different probiotics in bok choy cultivation

Observations on multiple mating flights of Apis dorsata queens

This observation is aimed at providing information for a reasonable comparative study on reproductive biology among the honeybee species. The research was carried out in 1996 in the submerged Melaleuca forest of southern Vietnam, where low-nesting colonies on man-made supports, rafters, allowed us to make detailed observations on the queens. Flights of six newly emerged queens were observed and after their final mating flights, queens were dissected to count the sperm number. The five investigated queens took their first flights 6 ± 1 (mean ± SD) days after emergence. Four queens took orientation flights of less than 3 min. One queen flew to mate without any orientation flight. Mating flights happened around sunset and lasted 15.4 ± 4.3 (n = 14) min. A queen undertook two to four mating flights and after fully mating, she had 5.5 ± 0.9 (n = 5) million sperm in her spermatheca. This study indicated the extreme polyandry in A. dorsata. © Inra/DIB/AGIB/Elsevier, Pari

Choosing the best machine tool in mechanical manufacturing

Machine tools are indispensable components and play an important role in mechanical manufacturing. The equipment of machine tools has a huge effect on the operational efficiency of businesses. Each machine tool type is described by many different criteria, such as cost, technological capabilities, accuracy, energy consumption, convenience in operation, safety for workers, working noise, etc. If the selection of machine is only based on one or several criteria, it will be really easy to make mistakes, which means it is not possible to choose the real best machine. A machine is considered to be the best only when it is chosen based on all of its criteria. This work is called multi-criteria decision-making (MCDM). In this study, the selection of machine tools has been done using two different multi-criteria decision-making methods, including the FUCA method (Faire Un Choix Adéquat) and the CURLI method (Collaborative Unbiased Rank List Intergration). These are two methods with very different characteristics. When using the FUCA method, it is necessary to normalize the data and determine the weights for the criteria. Meanwhile, if using the CURLI method, these two things are not necessary. The selection of these two distinct methods is intended to produce the most generalizable conclusions. Three types of machine tool, which are considered in this study, include grinding machine, drilling machine and milling machine. The number of grinders that were offered for selection was twelve, the number of drills that were surveyed in this study was thirteen, while nine were the number of milling machines that were given for selection. The objective of this study is to determine the best solution in each type of machine. The results of ranking the machines are very similar when using the two mentioned methods. Specially, in all the surveyed cases, the two methods FUCA and CURLI always find the same best alternative. Accordingly, it is possible to firmly come to a conclusion that the FUCA method and the CURLI method are equally effective in machine tool selection. In addition, this study has determined the best three machines corresponding to the three different machine type

Unique Shortest Vector Problem for max norm is NP-hard

The unique Shortest vector problem (uSVP) in lattice theory plays a crucial role in many public-key cryptosystems. The security of those cryptosystems bases on the hardness of uSVP. However, so far there is no proof for the proper hardness of uSVP even in its exact version. In this paper, we show that the exact version of uSVP for $\ell_\infty$ norm is NP-hard. Furthermore, many other lattice problems including unique Subspace avoiding problem, unique Closest vector problem and unique Generalized closest vector problem, for any $\ell_p$ norm, are also shown to be NP-hard

Outage performance of underlay cognitive radio networks over mix fading environment

In this paper, the underlay cognitive radio network over mix fading environment is presented and investigated. A cooperative cognitive system with a secondary source node S, a secondary destination node D, secondary relay node Relay, and a primary node P are considered. In this model system, we consider the mix fading environment in two scenarios as Rayleigh/Nakagami-m and Nakagami-m/Rayleigh Fading channels. For system performance analysis, the closed-form expression of the system outage probability (OP) and the integral-formed expression of the ergodic capacity (EC) are derived in connection with the system's primary parameters. Finally, we proposed the Monte Carlo simulation for convincing the correctness of the system performance