Thermokinetic study of the isomerization of isocyanic acid

In this work, the detailed study on the mechanism, kinetics and thermochemistry of the isomerization of isocyanic is described. Theoretical study was carried out by ab initio molecular orbital theory based on the CCSD(T) and B3LYP/6-311++G(3df,2p) methods in conjunction with statistical theoretical kinetic Rice-Ramsperger-Kassel-Marcus (RRKM) Master equation calculations. The potential energy surface (PES) for the isomeric reactions was also examined. At 760 Torr pressure, temperature dependent rate constants of the isomeric reactions HNCO ® HOCN (a), HNCO  ® H(CNO) (b) and HNCO ® H(NCO) (c) were: k(T) (a) = 10-37.70.T13.09.e-93.30kcal/mol/RT, k(T) (b)  = 103.46.T1.76.e-93.98kcal/mol/RT, k(T) (c) = 10-28.50.T10.61.e-91.16kcal/mol/RT respectively. Calculated results show that the isomerization of isocyanic acid may take place via three mechanisms and have very high barriers; all rate constants of them are very small in the temperature range from 300 to 2000 K. Keywords. Potential energy surface, isocyanic acid, density function theory, isomerization

Optimal condition for Propagation and Growing of Dendrobium thyrsiflorum

Dendrobium thyrsiflorum is a medicinal orchid that is being gradually destroyed due to over-exploitation. This research focuses on in vitro production of D. thyrsiflorum plantlet under optimal acclimatization conditions. The results of the study showed that the best medium for seed germination was MS basal medium (full-strength MS nutrient plus 100 ml L-1 coconut water; 7 g L-1 agar, 30 g L-1 sucrose, and 0.5 g L-1 active charcoal) supplemented with 60 g L-1 mashed sweet potatoes, which induces 97.8% of seed germination. The shoot was well developed in MS basal medium supplemented with 60 g L-1 mashed sweet potatoes and 0.4 mg L-1 6-Benzylaminopurine (BA) and, corpulent and green in shoot morphology. The shoot multiplication rate was greatest on MS basal medium supplemented with 0.4 mg L-1 BA and 0.4 mg L-1 Kinetin with 4.53 times, and the shoot height was reported at 3.45 cm after 8 weeks of subculture. Further, The shoot was 100% rooting, with an average of 4.51 roots/shoot and 5.34 cm per root in length when the shoot was implanted on MS basal medium plus 60 g L-1 mashed sweet potatoes and 0.75 g L-1 active charcoal. Especially, plantlets after transplanting to the orchid net house reached a 94.8% survival rate on tree fern after 24 weeks. Hence, the results of the study suggested a successful production of D. thyrsiflorum plantlet on the selected media compositions

Perceived Risk, Investment Performance and Intentions in Emerging Stock Markets

The study built the new measurement scales of risk perception in investing in stock types trading on the emerging stock market, and then explored the effects of perceived risk on investment performance and intentions of individual investors. The study employed mixed research methods including in-depth interviews, a pilot study involving 50 investors, a survey distributed to 465 retail investors. Results showed that perceived risk had direct positive impact on both investment performance and intentions. Perceived risk also had indirect influence on intentions to invest through investment performance. The study recommended investors drew attention to risk of stocks labelled as “warned”, “controlled”, and “halted trading”. The higher an investor has perceived risk of these stock types, the greater one has been satisfied with one's decisions on investing, the recent rate of return achieved as well as intended to invest in the next time. Moreover, securities corporations have regularly organized seminars, workshops or training courses about investing in the kinds of stocks and updated regulations of stock investment in time; particularly, improved the quality of listed companies to attract more investors to the stock market. Keywords: Investment performance, Intentions, Perceived risk, emerging stock markets. JEL Classifications: E44, G3

Analysis on the performance of reconfigurable intelligent surface-aided free-space optical link under atmospheric turbulence and pointing errors

Free-space optical (FSO) communication can provide the cost-efficient, secure, high data-rate communication links required for applications. For example, it provides broadband Internet access and backhauling for the fifth-generation (5G) and the sixth-generation (6G) communication networks. However, previous solutions to deal with signal loss caused by obstructions and atmospheric turbulence. In these solutions, reconfigurable intelligent surfaces (RISs) are considered hardware technology to improve the performance of optical wireless communication systems. This study investigates the pointing error effects for RIS-aided FSO links under atmospheric turbulence channels. We analyze the performance of RIS-aided FSO links influenced by pointing errors, atmospheric attenuation, and turbulence for the subcarrier quadrature amplitude modulation (SC-QAM) technique. Atmospheric turbulence is modeled using log-normal distribution for weak atmospheric turbulence. Several numerical outcomes obtained for different transmitter beam waist radius and pointing error displacement standard deviation are shown to quantitatively illustrate the average symbol error rate (ASER)

Towards a post-pandemic tourism recovery: An empirical study on the behavioural intention of using contactless payment and Covid-19 vaccination in Vietnam

This study highlights the applicability of the joint framework of the Theory of Planned Behaviour (TPB) and Protection Motivation Theory (PMT) to the utilization of contactless payment and Covid-19 vaccination in the context of post-pandemic tourism recovery in Vietnam. The conclusion of this study evidenced that the behavioural intention of using the contactless payment mode was positively driven by subjective norms, attitude, perceived behavioural control, risk perception, and perceived benefit. Moreover, tourists would feel safer when combining two protective measures, including contactless payment and vaccination. This study contributes to the field of contactless payment literature by applying a new different theoretical lens to explain the behaviour and intentions towards employing it generally and the field of tourism literature particularly

Effects of hormone and fertilizers on early flower induction of Dendrobium anosmum hybrid seedlings under ex vitro condition

Early flowering of new orchids is important to save time for selecting valuable flowers and artificial induction of flowering is a critical consideration in the orchid production industry. In this study, a new Dendrobium anosmum hybrid was generated by cross-breeding between D. anosmum ‘Chau Nhu’ and D. anosmum ‘Di Linh’. The ancestors and hybrid seedlings from in-vitro culture were trained in the net house and their growth and flowering were evaluated under ex vivo conditions with specific fertilizers and hormones. The results suggest that the hybrid plants grew better than their parents in terms of stem height, stem diameter, and leaf number. Growth hormones were applied to stimulate early flowering in matured hybrids and it was discovered that ‘Keiki pro’, a commercial hormone product, produced the best results, with a flowering rate of 66.67% after two applications. Hybrid flowers varied in width from 36.36% (3.0-6.0 cm) to 63.64 % (more than 6.0 cm) from ancestral width in medium-sized and large-sized flowers, respectively. Also, the hybrid flower colours was mostly a combination of pink/violet (75C) and purple/pink (68A), which is different from their parents. Importantly, the dorsal sepal, petal colours, and shape of hybrid flowers varied significantly among individual hybrids, between hybrids and their progenitors. Some mutations in the lips and columns of the novel hybrid flowers were also visualized. Hence, the D. anosmum hybrid seedlings successfully induced flowers after a year of culture under optimal hormones and fertilizers conditions. The results can serve as a critical reference for the early flowering of the orchid seedlings

Average symbol error rate analysis of reconfigurable intelligent surfaces based free-space optical link over Weibull distribution channels

Optical wireless communication (OWC) enables wireless connectivity using ultraviolet bands, infrared or visible. With its advantages features as high bandwidth, low cost, and operation in an unregulated spectrum. Free-space optical (FSO) communication systems are near terrestrial as a communication link between transceivers, the link is line-of-sight and successfully transmitted optical signals. Nevertheless, the optical signals transmissions over the FSO channels bring challenges to the system. To overcome the challenges posed by the FSO channels, the most common technique is to use relay stations, the most recent is the reconfigurable intelligent surfaces (RISs) technique. This study introduces a Weibull distribution model for a free-space optical communication link with RISs assisted, the parameter used to evaluate the performance of the system is the average symbol error rate (ASER). The RISs effect is examined by considering the influence of the transmitter beam waist radius, shape parameter, aperture radius, scale parameter, and signal-to-noise ratio on the ASER