DFT simulation of HCl leaching over cellulase-mimetic solid acid catalyst for possible application in biohydrogen production

Cellulase-mimetic solid acid catalysts (CMSAC), having both cellulose-binding and catalytic sites, are known to have much lower activation energy and higher catalytic activity than traditional solid acid catalysts. It is an emerging greener and cost-friendly solution for producing biofuel, such as bio-hydrogen, from lignocellulose. However, in 2018 the widely used CMSAC, sulfonated chloromethyl polystyrene, was found to have its catalytic activity attributed to the in-situ release of HCl during catalytic hydrolysis, which is unexpected. An ab initio quantum calculation based on density functional theory (DFT) is performed to study its reaction mechanism. Results have shown that the most probable mechanism responsible for the in-situ release of HCl is through SN1 nucleophilic substitution. The simulation also predicted a surface reaction activation energy of 1.56 eV (35.97 kcal/mol), along the predicted minimum energy path (MEP). This is the first ab initio study to theoretically predict the HCl leaching mechanism from CMSAC before its industrial application.     

Calf massager: Intervention for body muscle discomfort during prolonged standing

Many occupations require workers to stand for long periods of time without proper interventions, which causes discomfort in the back and lower limbs. Therefore, this study aims to assess the effectiveness in alleviating body muscle discomfort during prolonged standing through the use of a calf massager. This study was conducted among male workers at a manufacturer with production line workers and the list was obtained from the HR Department and simple random sampling was done by number categorization. A total of 100 respondents (50 respondents for both the control and the experimental groups) participated in this study. The experiment took place in a room with a similar setup for the production line. Each respondent was requested to perform the simulated task for 2 hr. For the experimental group, the calf massager was turned on every 15 min. At every 15‐min interval after turning on the calf massager, respondents from both groups were required to evaluate their discomfort level on a Borg's scale CR‐10 questionnaire. The results showed that the level of body discomfort among respondents in the experimental group reduced (20–30%) compared with that of the control group. Multivariate analysis results revealed that the discomfort rating for the lower back, knees, thighs, calves, and feet was significantly lower (p < .05) among the experimental group compared with the control group. For lower body parts, the lower back region was statistically significant (p < .05) at the 90th, 105th, and 120th min; the thigh region was statistically significant (p < .05) at the 120th min; the knee region was statistically significant (p < .05) at the 105th and 120th min; the calf region was statistically significant (p < .05) at all minute intervals except the 15th and 45th min, while the feet region, was statistically significant at the 105th and 120th min. Therefore, this study indicates that calf massage treatment is capable of reducing body muscle discomfort during prolonged standing and highlights the significance of calf massage.     

Smart gateways switching control algorithms based on tropospheric propagation forecasts

The use Q/V band spectrum for the feeder links of high throughput satellites and the need to cope with the significant propagation impairments at those frequencies motivate the development of smart diversity techniques. Those techniques aim at improving the availability level of the overall feeder link with a limited level of redundancy. The combinatorial gain of availability provided by those techniques can be obtained only if efficient switching methodologies are developed, performing the best trade‐off between system flexibility and channel prediction accuracy. This paper proposes various propagation forecast mechanisms for the control of switching between gateways in smart diversity, corresponding to various system assumptions in terms of required anticipation time for the triggering of the switches. The performances of those algorithms are then assessed against measured attenuation and meteorological data. It enables to evaluate the performance degradation regarding an idealized case.     

Examining the relationships among e-government maturity,corruption, economic prosperity and environmental degradation: A cross-country analysis

There is growing interest in the role and contribution of e-government to the levels of corruption, economic prosperity and environmental degradation of nation states. In this paper, we use publicly available archival data to explore the relationships among them. Results substantiate a significant relationship between (1) e-government maturity and corruption; and (2) e-government maturity, economic prosperity and environmental degradation through the mediating effects of corruption. The findings suggest that while e-government maturity did not contribute to economic prosperity and environmental degradation, its value could be realized indirectly via its impacts on corruption. Our findings contribute to the theoretical discourse on e-government impact by identifying the role of e-government in a country and provide indications to practice on enhancing its economic prosperity and lowering its environmental degradation by managing the levels of e-government maturity and corruption.     

Determination of hydrogen concentration in a-Si and a-Ge layers by elastic recoil detection analysis

In this work we have studied the individual a-Si and a-Ge hydrogenated layers prepared by RF sputtering on Si (100) substrates using Ar and H₂ gas mixture. The absolute value of atomic content of the H was determined by Elastic Recoil Detection Analysis (ERDA) with 1.6 MeV 4He⁺ beam. The dynamics of the out diffusion was investigated by annealing in high purity (99.999%) argon atmosphere at 350 °C for several hours. It was clearly shown that hydrogen can diffuse out faster from Ge film than from the Si one during annealing of the samples.     

On the formation of blisters in annealed hydrogenated a-Si layers

Differently hydrogenated radio frequency-sputtered a-Si layers have been studied by infrared (IR) spectroscopy as a function of the annealing time at 350°C with the aim to get a deeper understanding of the origin of blisters previously observed by us in a-Si/a-Ge multilayers prepared under the same conditions as the ones applied to the present a-Si layers. The H content varied between 10.8 and 17.6 at.% as measured by elastic recoil detection analysis. IR spectroscopy showed that the concentration of the clustered (Si-H)_n groups and of the (Si-H₂)_n (n ≥ 1) polymers increased at the expense of the Si-H mono-hydrides with increasing annealing time, suggesting that there is a corresponding increase of the volume of micro-voids whose walls are assumed from literature to be decorated by the clustered mono-hydride groups and polymers. At the same time, an increase in the size of surface blisters was observed. Also, with increasing annealing time, the total concentration of bonded H of any type decreases, indicating that H is partially released from its bonds to Si. It is argued that the H released from the (Si-H)_n complexes and polymers at the microvoid surfaces form molecular H₂ inside the voids, whose size increases upon annealing because of the thermal expansion of the H₂ gas, eventually producing plastic surface deformation in the shape of blisters.     

Response dynamics of phosphorelays suggest their potential utility in cell signalling

Phosphorelays are extended two-component signalling systems found in diverse bacteria, lower eukaryotes and plants. Only few of these systems are characterized, and we still lack a full understanding of their signalling abilities. Here, we aim to achieve a global understanding of phosphorelay signalling and its dynamical properties. We develop a generic model, allowing us to systematically analyse response dynamics under different assumptions. Using this model, we find that the steady-state concentration of phosphorylated protein at the final layer of a phosphorelay is a linearly increasing, but eventually saturating function of the input. In contrast, the intermediate layers can display ultrasensitivity. We find that such ultrasensitivity is a direct result of the phosphorelay biochemistry; shuttling of a single phosphate group from the first to the last layer. The response dynamics of the phosphorelay results in tolerance of cross-talk, especially when it occurs as cross-deactivation. Further, it leads to a high signal-to-noise ratio for the final layer. We find that a relay length of four, which is most commonly observed, acts as a saturating point for these dynamic properties. These findings suggest that phosphorelays could act as a mechanism to reduce noise and effects of cross-talk on the final layer of the relay and enforce its input–response relation to be linear. In addition, our analysis suggests that middle layers of phosphorelays could embed thresholds. We discuss the consequence of these findings in relation to why cells might use phosphorelays along with enzymatic kinase cascades.     

Photo-induced transformations in amorphous chalcogenide nano-multilayers

Photo-stimulated interdiffusion in a-Se/As₂S₃ amorphous chalcogenide nano-multilayers (ANML) is known as a useful method for amplitude-phase optical relief formation besides the known amorphous–amorphous or amorphous–crystalline photo-induced structural transformations (PST) in homogeneous chalcogenide layers, but it has a relatively narrow sensitivity spectral range and small amplitude modulation. Experimental evidences of improvement of optical recording processes were obtained in Te-, Bi-, Sb-containing nano-layered structures based on As₂S₃ matrix. The influence of nano-structuring and combination of components on the sensitivity, type of the recorded relief is discussed.