Effects of bribery on natural resource efficiency in Vietnam: moderating effects of market competition and credit constraints

This article uses small and medium-sized enterprises’ (SMEs) survey data in Vietnam from 2007 to 2015 to examine the effects of bribery on the natural resource efficiency of firms facing credit constraints and market competition. We also employ the disaggregated resource intensity by water, fuel, and electricity. Creditconstrained firms are broken down into those who have had formal loan applications denied (credit rationed) and those who do not apply for formal loans due to either the process being too difficult or the interest rate being too high (discouraged borrowers). Applying instrumental variable method to take into account the endogeneity problem, the empirical results provide evidence to support the ‘sanding-the-wheels of resource efficiency’ hypothesis. Among the three natural resources, inefficiency is most evident in water consumption. Furthermore, the effects become more sizable for micro-sized and informally registered firms since they have a lower bargaining power vis-a-vis public officials. Credit constraints and market competition pressure can reduce a firm’s ability to use natural resources efficientl

Welfare consequences of inconsistent monetary policy implementation in Vietnam

We develop a New Keynesian model featuring Calvo price setting and Calvo wage setting to quantify the welfare consequences of shifting trend inflation in Vietnam. To capture the characteristics of the Vietnamese economy, we use the Simulated Method of Moment and calibrate parameters jointly to match the important selected moments of Vietnamese data. The results show a severe consequence of a constant positive trend inflation and an exogenous shock to trend inflation, especially when a central bank sets a high level of inflation target. Among staggered price and wage contracts, the latter play a vital role in transmitting the adverse impacts of constant and shifting trend inflation into the economy. Based on our analyses, raising inflation targets would seem to be a bad policy prescription in Vietnam

Effects of R&D, networking and leadership roles on environmental innovation adoption in Vietnam’s SMEs

Although small and medium-sized enterprises (SMEs) constitute a majority of firms, they still have little knowledge about environmental issues and generally encounter difficulties when integrating environmental aspects into their activities. Similar arguments are also highlighted by Ha et al. in the case of Vietnam. This paper, therefore, builds a guideline for promoting SMEs’ organisational environmental innovation adoption based on Environmental Standard Certification (ESC) by investigating the effects of R&D, networking, and leadership roles in Vietnam. By using SME survey data in Vietnam from 2011 to 2015, the empirical results show that R&D spending and organisational capabilities proxied by already owning ESC are positively associated with green innovation implementation. We also find that either collaboration with different partners, including competitors, banks, and public agents or communication networks, affects firms’ decisions on green innovations. The demographic characteristics of managers such as gender, educational level, and knowledge about the environmental laws play determining roles in these decisions. Finally, we advanced the literature by indicating the moderating effects of men in leadership roles and leaders with better related knowledge on the impacts of firms’ internal resources (R&D) and firms’ international orientation (export)

Reclamation of Marine Chitinous Materials for Chitosanase Production via Microbial Conversion by Paenibacillus macerans

[[abstract]]: Chitinous materials from marine byproducts elicit great interest among biotechnologists for their potential biomedical or agricultural applications. In this study, four kinds of marine chitinous materials (squid pens, shrimp heads, demineralized shrimp shells, and demineralized crab shells) were used to screen the best source for producing chitosanase by Paenibacillus macerans TKU029. Among them, the chitosanase activity was found to be highest in the culture using the medium containing squid pens as the sole carbon/nitrogen (C/N) source. A chitosanase which showed molecular weights at 63 kDa was isolated from P. macerans cultured on a squid pens medium. The purified TKU029 chitosanase exhibited optimum activity at 60 ◦C and pH 7, and was stable at temperatures under 50 ◦C and pH 3-8. An analysis by MALDI-TOF MS revealed that the chitosan oligosaccharides (COS) obtained from the hydrolysis of water-soluble chitosan by TKU029 crude enzyme showed various degrees of polymerization (DP), varying from 3–6. The obtained COS enhanced the growth of four lactic acid bacteria strains but exhibited no effect on the growth of E. coli. By specialized growth enhancing effects, the COS produced from hydrolyzing water soluble chitosan with TKU029 chitinolytic enzymes could have potential for use in medicine or nutraceuticals.[[sponsorship]]MOST[[notice]]補正完

A hierarchical architecture for increasing efficiency of large photovoltaic plants under non-homogeneous solar irradiation

Under non-homogeneous solar irradiation, photovoltaic (PV) panels receive different solar irradiance, resulting in a decrease in efficiency of the PV generation system. There are a few technical options to fix this issue that goes under the name of mismatch. One of these is the reconfiguration of the PV generation system, namely changing the connections of the PV panels from the initial configuration to the optimal one. Such technique has been widely considered for small systems, due to the excessive number of required switches. In this paper, the authors propose a new method for increasing the efficiency of large PV systems under non-homogeneous solar irradiation using Series-Parallel (SP) topology. In the first part of the paper, the authors propose a method containing two key points: a switching matrix to change the connection of PV panels based on SP topology and the proof that the SP-based reconfiguration method can increase the efficiency of the photovoltaic system up to 50%. In the second part, the authors propose the extension of the method proposed in the first part to improve the efficiency of large solar generation systems by means of a two-levels architecture to minimize the cost of fabrication of the switching matrix

COMPLETE REPAIR FOR TETRALOGY OF FALLOT IN CHILDREN: SHORT-TERM OUTCOME IN A SINGLE CENTER

Tetralogy of Fallot is a common cyanotic congenital heart disease. Early surgery treatment gives patients a chance to have normal physical and mental health due to preventing complications of cyanosis and even death as a natural history of tetralogy of Fallot. This study aimed to show short-term outcomes (including the time of postoperative hospital stay and 30 days after discharge) of tetralogy of Fallot complete repair at the Department of Pediatric Cardiac Surgery, Cho Ray Hospital. A retrospective study was performed on the data of medical documents of 38 patients, who underwent complete repair for tetralogy of Fallot with full sternotomy and cardiopulmonary bypass from March 2017 to December 2019, following a collection form. The results showed the average age and weight were 33.89±13.02 months and 11.77±2.48 kg. The cardiopulmonary bypass time was 147.74±12.48 mins, the aortic cross-clamp time 104.84±9.73 mins, the mechanical ventilation time 31.14±10.75 hours, the duration of stay in the intensive care unit 58.03±13.56 hours, the postoperative hospital stay time 10.12±1.5 days, and the mortality rate 2.6%. The study concludes that the short-term surgical outcome of complete repair for tetralogy of Fallot in lightweight children is safe and effective with a low mortality rate

Cloning and expression of gene FanC-2NT encoding K99-2NT fimbrial antigen of enterotoxigenic Escherichia coli from diarrheic post-weaning piglets

Background and Purpose: The K99 (F5) is one pilus adhesin that mediates the attachment of enterotoxigenic E. coli (ETEC) strains to small intestines to cause to diarrhea in piglets, lambs and newborn calves. In this work, we carried out cloning and expression of the mature peptide of FanC subunit, K99 fimbriae, one of the most common adhesive antigens in E. coli. Materials and Methods: E. coli 2NT strain was isolated from fecal samples of post-weaning piglets with diarrhea. The coding sequence of the mature peptide of K99-2NT subunit was isolated by PCR amplification and cloned into pGEM®-T Easy vector for sequencing using fluorescent dideoxy-terminator method. Expression of K99-2NT protein which was inserted into pET200/D-TOPO vector induced with IPTG. The PCR product and expression level of protein was examined by agarose gel electrophoresis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis, respectively. Results and Conclusions: We cloned and expressed successfully the mature peptide of K99 subunit with molecular weight of approximately 17.5 kDa from E. coli 2NT strain (named K99-2NT). Nucleotide sequence of the K99-2NT subunit coding region of fanC-2NT gene is 477 bp in length and is 99% similarity with that of fanC gene (accession no: M35282). Highest expression level occurred after 12 h of induction with 0.75 mM IPTG at 37oC. This subunit antigen will be tested for immune response of rat in the next time

Bioactivity-guided purification of novel herbal antioxidant and anti-NO compounds from Euonymus laxiflorus Champ

[[abstract]]Euonymus laxiflorus Champ., a medicinal herb collected in Vietnam, has been reported to show several potent bioactivities, including anti-NO, enzyme inhibition, hypoglycemic and antidiabetic effects. Recently, the antioxidant activity of Euonymus laxiflorus Champ. trunk bark (ELCTB) has also been reported. However, the active antioxidant and anti-NO constituents existing in ELCTB have not been reported in the literature. The objective of this study was to purify the active antioxidants from ELCTB and investigate the anti-NO effect of the major constituents. Twenty-two phenolics isolated from ELCTB, including 12 compounds newly isolated in this study (1–12) and 10 constituents obtained from our previous work, were evaluated for their antioxidant activity. Of these, 12 compounds (4–6, 9, 13–15, 18–22) showed a potent antioxidant capacity (FRS50 = 7.8–58.11 µg/mL), in comparison to α-tocopherol (FRS50 = 23 µg/mL). In the anti-NO activity tests, Walterolactone A (1a) and B (1b) β-D-glucopyranoside (13) demonstrated the most effective and comparable activity to that of quercetin with max inhibition and IC50 values of 100%, 1.3 µg/mL, and 100%, 1.21 µg/mL, respectively. The crude extract and its major compounds showed no cytotoxicity on normal cells. Notably, three constituents (9, 11, and 12) were identified as new compounds, another three constituents, including 1, 7, and 8, were found to be new natural products, constituents 9 and 13 were determined to be new antioxidants, and compound 13 was reported to have novel potent anti-NO activity for the first time. The results of this study contribute to the enrichment of new natural products and compounds, as well as the novel biological activity of constituents isolated from Euonymus laxiflorus Champ. The current study also indicates ELCTB as a rich natural source of active phenolics. It is suggested that ELCTB could be developed as a health food with promising antioxidant and anti-NO effects, as well as other beneficial biological activities.[[sponsorship]]科技部[[notice]]補正完

Simultaneous quantitative analyses of Tanshinone I, Cryptotanshinone, and Tanshinone IIA in Danshen (Salvia miltiorrhiza Bunge) cultivated in Vietnam using LC-MS/MS

By using chromatography methods, the principal compounds tanshinon I, cryptotanshinone, tanshinone IIA were isolated from danshen (Salvia miltiorrhiza Bunge). Based on the spectroscopic data (1H-NMR, 13C-NMR and ESI-MS mass spectra), the structures were determined. The compound was purified (purity > 99.8%) by Agilent 218 purification system, which was used as the standard for analyzing tanshinon I, cryptotanshinone, tanshinone IIA in six samples. In this study, one LC-MS/MS method was developed for the simultaneous quantitative determination of three bioactive principles, tanshinone I, cryptotanshinone, and tanshinone IIA in Radix Salviae miltiorrhizae (RSM, the root of S. miltiorrhiza). The quantification of these diterpenoids is based on the fragments of [M+H]+ under collision-activated conditions and in selected reaction monitoring (SRM) mode. The quantitative method is validated by determining the mean recovery from fortified samples of tanshinone I, cryptotanshinone, and tanshinone IIA as higher than 98%. The established method is successfully applied to the quality assessment of six batches of RSM samples collected from different regions of Vietnam. The results show that Lam Dong sample has the highest tanshinone I content (4.4286±0.0009 µg/mg), meanwhile Muong Long sample has the lowest (1.2717±0.0013µg/mg). Lam Dong sample has the highest cryptotanshinone content (8.1589±0.0006 µg/mg), whereas Guangxi-China sample has the lowest (2.8630±0.0008 µg/mg). Ha Giang sample has the highest tanshinone IIA content (13.0252±0.0004 µg/mg), whereas Muong Long sample has the lowest (3.8278±0.0003 µg/mg)