The orientation and magnitude of the molecular electric dipole moment are key properties relevant to topics ranging from the nature of intermolecular interactions to the quantitative analysis of ...complex gas-phase mixtures, such as chemistry in astrophysical environments. Stark effect measurements on rotational spectra have been the method of choice for isolated molecules but have become less common with the practical disappearance of Stark modulation spectrometers. Their role has been taken over by supersonic expansion measurements within a Fabry-Perot resonator cavity, which introduces specific technical problems that need to be overcome. Several of the adopted solutions are described and compared. Presently, we report precise electric dipole moment determinations for the two most stable conformers of the selected molecules of confirmed or potential astrophysical relevance: n-propanol, n-butanol, and n-butyl cyanide. All dipole moment components have been precisely determined at supersonic expansion conditions by employing specially designed Stark electrodes and a computer program for fitting the measured Stark shifts, inclusive of cases with resolved nuclear quadrupole hyperfine structure. The experimental values are compared with suitable quantum chemistry computations. It is found that, among the tested levels of computation, vibrationally averaged dipole moments are the closest to the observation and the molecular values are, as in the lighter molecules in the series, largely determined by the hydroxyl or nitrile groups.
A study of the behavior of NB-IoT wireless communication in an industrial indoor environment was conducted in this paper. With Wireless Insite software, a scenario in the industrial sector was ...simulated and modeled. Our research examined how this scenario or environment affected the communication parameters of NB-IoT's physical layer. In this context, throughput levels among terminals as well as between terminals and transceiver towers, the power received at signal destination points, signal-to-noise ratios (SNRs) in the environment, and distances between terminals and transceivers are considered. These simulated results are also compared with the calculated or theoretical values of these parameters. The results show the effect of the industrial setting on wireless communication. The differences between the theoretical and simulated values are also established.
Accurate information on gas-to-particle partitioning is needed to model secondary organic aerosol formation. However, determining reliable saturation vapor pressures of atmospherically relevant ...multifunctional organic compounds is extremely difficult. We estimated saturation vapor pressures of α-pinene-ozonolysis-derived secondary organic aerosol constituents using Filter Inlet for Gases and AEROsols (FIGAERO)-chemical ionization mass spectrometer (CIMS) experiments and conductor-like screening model for real solvents (COSMO-RS). We found a good agreement between experimental and computational saturation vapor pressures for molecules with molar masses around 190 g mol.sup.-1 and higher, most within a factor of 3 comparing the average of the experimental vapor pressures and the COSMO-RS estimate of the isomer closest to the experiments. Smaller molecules likely have saturation vapor pressures that are too high to be measured using our experimental setup. The molecules with molar masses below 190 g mol.sup.-1 that have differences of several orders of magnitude between the computational and experimental saturation vapor pressures observed in our experiments are likely products of thermal decomposition occurring during thermal desorption. For example, dehydration and decarboxylation reactions are able to explain some of the discrepancies between experimental and computational saturation vapor pressures. Based on our estimates, FIGAERO-CIMS can best be used to determine saturation vapor pressures of compounds with low and extremely low volatilities at least down to 10.sup.-10 Pa in saturation vapor pressure.
The set of TXsub.3-TrXsub.2 (T = C, Si, Ge; Tr = B, Al, Ga; X = F, Cl, Br) molecules offers a rather unique opportunity to study both σ-hole and π-hole dimerization on the tetrel and triel ends, ...respectively. According to the molecular electrostatic potential (MEP) distribution, the π-hole extrema (acidic sites) were more intense than their σ-hole counterparts. The molecules owning the most (CXsub.3-AlXsub.2) and least (SiXsub.3-BXsub.2) intense π-holes were chosen to evaluate their capacities to attract one and two HCN molecules (Lewis bases). We discovered that the energetic characteristics of π-hole dimers severely conflict with the monomers MEP pattern since the weakest π-hole monomer forms a dimer characterized by interaction energy compared to those created by the monomers with noticeably greater power in the π-hole region. This outcome is due to the deformation of the weakest π-hole donor. Furthermore, the MEP analysis for monomers in the geometry of respective dimers revealed a “residual π-hole” site that was able to drive second ligand attachment, giving rise to the two “unusual trimers” examined further by the NCI and QTAIM analyses. Apart from them, the π-hole/π-hole and σ-hole/π-hole trimers have also been obtained throughout this study and described using energetic and geometric parameters. The SAPT approach revealed details of the bonding in one of the “unusual trimers”. Finally, Born-Oppenheimer Molecular Dynamics (BOMD) simulations were carried out to investigate the time evolution of the interatomic distances of the studied complexes as well as their stability.
A high prevalence of hypertension is found in Low- and Middle-income Countries (LMICs) including in Indonesia. However, hypertension awareness, treatment, and control are relativity poor. A ...community-based program to screen and educate people on non-communicable disease prevention (POSBINDU) was launched by the Indonesian government. However, the association between participation in the POSBINDU program with increasing knowledge, attitude, and practice of hypertension has not been widely assessed. In this study, we compared the knowledge, attitudes, and practices among people who accessed the POSBINDU and those who did not access the POSBINDU program. Subsequently, factors associated with the knowledge, attitudes, and practices among people who accessed the POSBINDU and those who did not access the POSBINDU were explored. This was an observational study with a cross-sectional design measuring the knowledge, attitudes, and practices for hypertension control in four districts in Indonesia from October 2019 to January 2020. A total of 1,988 respondents were included in this study. A questionnaire was used to assess the knowledge, attitudes, and practices of hypertension. Simple logistic regression was used to investigate the correlation between the characteristics of respondents and knowledge, attitudes, and practice status. Multiple logistic regression tests were conducted to investigate factors associated with knowledge, attitudes, and practice status. We found that people who accessed POSBINDU had higher odds of having better knowledge (aOR:1.4; 95%CI:1.2-1.8), however, accessed to POSBINDU was associated with lower attitudes (aOR:0.6; 85%CI: 0.5-0.7) and had no association with hypertension-related practice. People who accessed POSBINDU have an association with good knowledge, but the association with good attitude and practice was less clear. Therefore, an improvement in the POSBINDU program is needed to increase the attitudes and practices of hypertension.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The challenge of improving the activity of TiOsub.2 by modifying it with metals and using it for targeted applications in microreactor environments is an active area of research. Recently, ...microreactors have emerged as successful candidates for many photocatalytic reactions, especially for the selective oxidation process. The current work introduces ultrasound-assisted catalyst deposition on the inner walls of a perfluoro-alkoxy alkane (PFA) microtube under mild conditions. We report Cu-Au/TiOsub.2 and Fe-Au/TiOsub.2 nanoparticles synthesized using the sol-gel method. The obtained photocatalysts were thoroughly characterized by UV-Vis diffuse-reflectance spectroscopy (DRS), high-resolution scanning electron microscopy (HR-SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray diffraction analysis (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and Nsub.2 physisorption. The photocatalytic activity under UV (375 nm) and visible light (515 nm) was estimated by the oxidation of lignin-based model aromatic alcohols in batch and fluoropolymer-based flow systems. The bimetallic catalyst exhibited improved photocatalytic selective oxidation. Herein, four aromatic alcohols were individually investigated and compared. In our experiments, the alcohols containing hydroxy and methoxy groups (coniferyl and vanillin alcohol) showed high conversion (93% and 52%, respectively) with 8% and 17% selectivity towards their respective aldehydes, with the formation of other side products. The results offer an insight into ligand-to-metal charge transfer (LMCT) complex formation, which was found to be the main reason for the activity of synthesized catalysts under visible light.
International business (IB) researchers have been slow to embrace a configurational approach in hypothesis formulation and empirical analysis. Yet, much of what IB scholars study is inherently ...configurational: various explanatory factors and their interplay simultaneously determine the outcome(s) studied, such as governance choice or firm-level performance. The mismatch between the nature of the empirical phenomena studied on the one hand, and hypothesis formulation and empirical methods deployed on the other, explains why many quantitative empirical studies in IB are overly reductionist, relying on hypotheses that assume linear (or simple, curvilinear), unifinal, and symmetrical effects. In this Editorial, we introduce IB scholars to contemporary configurational thinking and its analytical tool, fuzzy-set qualitative comparative analysis (fsQCA). We discuss this tool’s main tenets, advantages, and disadvantages. We review the limited prior IB research using this approach and present a wide range of IB phenomena where it could be usefully applied. We propose that contemporary configurational thinking and fsQCA can help scholars produce insights more closely aligned with the complex realities of international business than conventional research approaches.
Two kinds of core-shell composite particles, i.e., mesoporous-SiO.sub.2@Cu (m-SiO.sub.2@Cu) and mesoporous-SiO.sub.2@TiO.sub.2@Cu (m-SiO.sub.2@TiO.sub.2@Cu) microspheres, were synthesized by coating ...Cu nanoparticles on the surfaces of m-SiO.sub.2 and m-SiO.sub.2@TiO.sub.2 microspheres. Results show that the m-SiO.sub.2 spheres have rougher surfaces and larger specific surface areas than the SiO.sub.2 microspheres. Compared with the m-SiO.sub.2@Cu microsphere, the m-SiO.sub.2@TiO.sub.2@Cu microsphere has a hollow structure. Both catalysts showed high catalytic activity to degrade methyl violet and methylene blue dyes. The degradations of two dyes using the m-SiO.sub.2@Cu approached 100% after 30 min, while it is slightly less, around 90% for the m-SiO.sub.2@TiO.sub.2@Cu. The catalytic activity of m-SiO.sub.2@Cu lies in Cu nanoparticles, which have large specific surface areas and are insensitive to light. The catalytic activity of m-SiO.sub.2@TiO.sub.2@Cu not only lies in Cu nanoparticles, but also in TiO.sub.2, which is sensitive to light. What's more, Cu and TiO.sub.2 work as metal/semiconductor heterojunction, which enhances the electron-hole separation in m-SiO.sub.2@TiO.sub.2@Cu. Graphical abstract
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