Oxygen reduction reaction activity in non-precious single-atom (M–N/C ) catalysts-contribution of metal and carbon/nitrogen framework-based sites.

We examine the performance of a number of single-atom M-N/C electrocatalysts with a common structure in order to deconvolute the activity of the framework N/C support from the metal M-N4 sites in M-N/Cs. The formation of the N/C framework with coordinating nitrogen sites is performed using zinc as a templating agent. After the formation of the electrically conducting carbon-nitrogen metal-coordinating network, we (trans)metalate with different metals producing a range of different catalysts (Fe-N/C, Co-N/C, Ni-N/C, Sn-N/C, Sb-N/C, and Bi-N/C) without the formation of any metal particles. In these materials, the structure of the carbon/nitrogen framework remains unchanged-only the coordinated metal is substituted. We assess the performance of the subsequent catalysts in acid, near-neutral, and alkaline environments toward the oxygen reduction reaction (ORR) and ascribe and quantify the performance to a combination of metal site activity and activity of the carbon/nitrogen framework. The ORR activity of the carbon/nitrogen framework is about 1000-fold higher in alkaline than it is in acid, suggesting a change in mechanism. At 0.80 VRHE, only Fe and Co contribute ORR activity significantly beyond that provided by the carbon/nitrogen framework at all pH values studied. In acid and near-neutral pH values (pH 0.3 and 5.2, respectively), Fe shows a 30-fold improvement and Co shows a 5-fold improvement, whereas in alkaline pH (pH 13), both Fe and Co show a 7-fold improvement beyond the baseline framework activity. The site density of the single metal atom sites is estimated using the nitrite adsorption and stripping method. This method allows us to deconvolute the framework sites and metal-based active sites. The framework site density of catalysts is estimated as 7.8 × 1018 sites g-1. The metal M-N4 site densities in Fe-N/C and Co-N/C are 9.4 × 1018 sites-1 and 4.8 × 1018 sites g-1, respectively

Broadband spin-controlled focusing via logarithmic-spiral nanoslits of varying width

This work presents analytical, numerical and experimental demonstrations of light diffracted through a logarithmic spiral (LS) nanoslit, which forms a type of switchable and focus-tunable structure. Owing to a strong dependence on the incident photon spin, the proposed LS-nanoslit converges incoming light of opposite handedness (to that of the LS-nanoslit) into a confined subwavelength spot, while it shapes light with similar chirality into a donut-like intensity profile. Benefitting from the varying width of the LS-nanoslit, different incident wavelengths interfere constructively at different positions, i.e., the focal length shifts from 7.5 μm (at λ = 632.8 nm) to 10 μm (at λ = 488 nm), which opens up new opportunities for tuning and spatially separating broadband light at the micrometer scale

The Role of Organizational Culture in Job Satisfaction and Turnover: A Study of Pakistani Employees

The human capital becomes a significant achievement of every organization in the context of the transformation of the fundamental principles in doing business. Every business structure creates and maintains a unique organizational culture that determines the degree of comfortable conditions for employees in their workplace, the level of their interest in the successful operation of the company and the desire to gain leadership in the market. The human resources and the degree of workers’ satisfaction with jobs directly affect the performance of the company

Effect of Moringa oleifera (Lam.) pods as feed additive on egg antioxidants, chemical composition and performance of commercial layers

The present study was designed to investigate the influence of Moringa oleifera (Lam.) pod meal (MPM) on production, immunity, and functional food index of chicken eggs. Two hundred HyLine W36 layer birds aged 50 weeks, 1469 ± 46.63 g, were assigned to four treatments in a completely randomized design, with five replicates and ten birds each. Diets A, B, C, and D were formulated with the same caloric and protein levels, but with differing MPM dose levels of 0, 5, 10, and 15g MPM/kg finisher diet, respectively. Data for production performance, quality, and chemical composition of eggs were analysed by one-way ANOVA, and means were compared with Duncan’s multiple range test. As a result of this study, feed conversion ratio (FCR) and egg mass (EM) were significantly decreased and recorded lowest in Group B, which was offered 5 g/kg above the basal diet. Bioactives such as β-carotene, quercetin, and selenium levels were increased (540, 121, & 72.21μg/100g of yolk, respectively), whereas cholesterol levels in egg yolk and serum were decreased significantly, that is, 201.87 mg/100g and 8.47 mg/dl, respectively. Serum biochemical indicators, including serum glutamic-pyruvic transaminase (SGPT), glucose, creatinine and cholesterol levels, were lowered significantly. Proximate analysis of egg yolk showed that moisture and ether extract were decreased, whereas crude protein (CP), ash and minerals, sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), and phosphorus (P) contents were increased. The outcomes of this study showed that MPM supplementation affects EM, serum biochemistry and bioactive compounds of the egg yolk positively. Keywords: Antibody titers, β-carotene, cholesterol, egg quality, quercetin, seleniu

Evaluating the Influences of Natural Resources and Ageing People on CO2 Emissions in G-11 Nations: Application of CS-ARDL Approach

Globalization as well as the ratio of ageing people in the group of 11 (G-11) countries has seen a rapid increase in recent years. Therefore, this study aims to provide effective policy recommendations for sustainable development goals 13, 8, and 7, for the G-11 countries. This work estimates the impact of natural resources and the ageing population on the emission of carbon dioxide (CO2) in G-11 countries using panel data from 1990–2020. For empirical results, second-generation methods were applied. The Westerlund co-integration test that assesses co-integration confirms the firm association among the parameters, and the values of coefficient of the cross-sectional autoregressive distributed lag (CS-ARDL) approach show that a 1% increase in the ageing population will lower the emissions of CO2 by 13.41% among G-11 countries. Moreover, the findings show that there exists an environmental Kuznets curve (EKC) among natural resources, globalization, economic growth, ageing people, and the emission of CO2. Based on the findings, this work presents some important policy implications for achieving sustainable growth in the G-11 countries. These countries need to lower the amount of energy obtained from fossil fuels to improve air quality. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

Dynamic Profiling of β-Coronavirus 3CL Mpro Protease Ligand-Binding Sites

β-coronavirus (CoVs) alone has been responsible for three major global outbreaks in the 21st century. The current crisis has led to an urgent requirement to develop therapeutics. Even though a number of vaccines are available, alternative strategies targeting essential viral components are required as a backup against the emergence of lethal viral variants. One such target is the main protease (Mpro) that plays an indispensable role in viral replication. The availability of over 270 Mpro X-ray structures in complex with inhibitors provides unique insights into ligand-protein interactions. Herein, we provide a comprehensive comparison of all nonredundant ligand-binding sites available for SARS-CoV2, SARS-CoV, and MERS-CoV Mpro. Extensive adaptive sampling has been used to investigate structural conservation of ligand-binding sites using Markov state models (MSMs) and compare conformational dynamics employing convolutional variational auto-encoder-based deep learning. Our results indicate that not all ligand-binding sites are dynamically conserved despite high sequence and structural conservation across β-CoV homologs. This highlights the complexity in targeting all three Mpro enzymes with a single pan inhibitor

Does Globalization Cause Greenhouse Gas Emissions in Pakistan? A Promise to Enlighten the Value of Environmental Quality

Global environmental issues such as environmental degradation, climate change, and global warming have posed a threat to the global economy, including Pakistan. The primary source of these problems is greenhouse gas emissions. These emissions are the result of human activity. The objective of the study was to investigate the symmetric and asymmetric relationship between globalization and greenhouse gas emissions in Pakistan. The ARDL modern econometric techniques of the time series model were used. Firstly, the stationarity test favors the use of the ARDL model in this study. The BDS test result confirmed that the ARDL model has a non-linearity issue. As a result, the ARDL approach was used to test both the symmetric and asymmetric effect. The results of the asymmetric ARDL model are more robust and reliable than those of the symmetric ARDL model. According to the results of the symmetric ARDL, economic, social, and political globalization have a positive relationship with greenhouse gas emissions in both the short and long run. Furthermore, the long-run results of the asymmetric ARDL model show that positive and negative shocks of economic and political globalization have positive and negative shock effects on greenhouse gas emissions. In the long run, however, the positive shock of social globalization has a negative relationship with greenhouse gas emissions. According to the results of impulse response functions, economic globalization has a significantly more relationship with greenhouse gas emissions than social and political globalization. A policy should be developed that allows only the positive effects of globalization while prohibiting the negative effects of globalization. © 2022 by the authors