An improved nondominated sorting genetic algorithm-II (INSGA-II) has been proposed for optimal planning of multiple distributed generation (DG) units in this paper. First, multiobjective functions ...that take minimum line loss, minimum voltage deviation, and maximal voltage stability margin into consideration have been formed. Then, using the proposed INSGA-II algorithm to solve the multiobjective planning problem has been described in detail. The improved sorting strategy and the novel truncation strategy based on hierarchical agglomerative clustering are utilized to keep the diversity of population. In order to strengthen the global optimal searching capability, the mutation and recombination strategies in differential evolution are introduced to replace the original one. In addition, a tradeoff method based on fuzzy set theory is used to obtain the best compromise solution from the Pareto-optimal set. Finally, several experiments have been made on the IEEE 33-bus test case and multiple actual test cases with the consideration of multiple DG units. The feasibility and effectiveness of the proposed algorithm for optimal placement and sizing of DG in distribution systems have been proved.
Aims. We aim to reveal the physical properties and chemical composition of the cores in the California molecular cloud (CMC), so as to better understand the initial conditions of star formation. ...Methods. We made a high-resolution column density map (18.2′′) with Herschel data, and extracted a complete sample of the cores in the CMC with the fellwalker algorithm. We performed new single-pointing observations of molecular lines near 90 GHz with the IRAM 30m telescope along the main filament of the CMC. In addition, we also performed a numerical modeling of chemical evolution for the cores under the physical conditions. Results. We extracted 300 cores, of which 33 are protostellar and 267 are starless cores. About 51% (137 of 267) of the starless cores are prestellar cores. Three cores have the potential to evolve into high-mass stars. The prestellar core mass function (CMF) can be well fit by a log-normal form. The high-mass end of the prestellar CMF shows a power-law form with an index α = −0.9 ± 0.1 that is shallower than that of the Galactic field stellar mass function. Combining the mass transformation efficiency (ε) from the prestellar core to the star of 15 ± 1% and the core formation efficiency (CFE) of 5.5%, we suggest an overall star formation efficiency of about 1% in the CMC. In the single-pointing observations with the IRAM 30m telescope, we find that 6 cores show blue-skewed profile, while 4 cores show red-skewed profile. HCO+/HNC and HCO+/N2H+ in protostellar cores are higher than those in prestellar cores; this can be used as chemical clocks. The best-fit chemical age of the cores with line observations is ~5 × 104 yr.
Abstract
Hot corinos are of great interest due to their richness in interstellar complex organic molecules (COMs) and the consequent potential prebiotic connection to solar-like planetary systems. ...Recent surveys have reported an increasing number of detected hot corinos in Class 0/I protostars; however, the relationships between their physical properties and the hot-corino signatures remain elusive. In this study, our objective is to establish a general picture of the detectability of hot corinos by identifying the origins of the hot-corino signatures in the sample of young stellar objects (YSOs) obtained from the Atacama Large Millimeter/submillimeter Array Survey of Orion Planck Galactic Cold Clumps project. We apply spectral energy distribution modeling to our sample and identify the physical parameters of the modeled YSOs directly, linking the detection of hot-corino signatures to the envelope properties of the YSOs. Imaging simulations of the methanol emission further support this scenario. We therefore posit that the observed COM emission originates from the warm inner envelopes of the sample YSOs, based on both the warm region size and the envelope density profile. The former is governed by the source luminosity and is additionally affected by the disk and cavity properties, while the latter is related to the evolutionary stages. This scenario provides a framework for detecting hot-corino signatures toward luminous Class 0 YSOs, with fewer detections being observed toward similarly luminous Class I sources.
A novel double-input pulsewidth-modulation (PWM) dc/dc converter for high-/low-voltage sources is proposed in this paper. With a PWM control scheme, the proposed double-input dc/dc converter can draw ...power from two different voltage sources simultaneously or individually. The operation modes and the steady-state analysis of the proposed double-input dc/dc converter are introduced in detail. The PWM control scheme for the power flow balancing is also presented. By using a single passive lossless soft-switching cell, switching losses of all power switches can be reduced significantly. Finally, experimental measurements are demonstrated to verify the performance of the proposed converter
An asymmetric unactivated alkene/CH bond difunctionalization reaction for the concomitant construction of CCF3 and CO bonds was realized by using a Cu/Brønsted acid cooperative catalytic system, ...thus providing facile access to valuable chiral CF3‐containing N,O‐aminals with excellent regio‐, chemo‐, and enantioselectivity. Mechanistic studies revealed that this reaction may proceed by an unprecedented 1,5‐hydride shift involving activation of unactivated alkenes and a radical trifluoromethylation to initiate subsequent enantioselective functionalization of CH bonds. Control experiments also suggested that chiral Brønsted acid plays multiple roles and not only controls the stereoselectivity but also increases the reaction rate through activation of Togni’s reagent.
En route: The title redox‐neutral reaction provides a convenient route to valuable enantioenriched trifluoromethylated N,O‐aminals in good to excellent yields and with excellent regio‐, chemo‐, and enantioselectivity. The reaction features a CuI/Brønsted acid system and broad substrate scope.
Purpose
The purpose of this study was to investigate the moderating effects of organizational justice and workplace friendship on the relationship between workplace bullying and hotel employees’ ...well-being.
Design/methodology/approach
The research sample included 310 entry-level employees of international tourism hotels in Taiwan. This study adopted hierarchical regression for data analysis.
Findings
The study found that workplace bullying negatively impacted on hotel employees’ well-being. Organizational justice and workplace friendship had significantly positive effects on hotel employees’ well-being. Compared with workplace friendship, organizational justice had a significant moderating effect on the relationship between workplace bullying and hotel employees’ well-being.
Originality/value
In the research fields of hospitality, past studies failed to use organizational justice and workplace friendship to moderate the relationship between workplace bullying and hotel employees’ well-being. This study confirmed that organizational justice could effectively buffer the negative effect of workplace bullying on hotel employees’ well-being.
A chiral‐NHC‐catalyzed highly diastereo‐ and enantioselective dearomatizing double Mannich reaction of isoquinolines was developed that provides a powerful and straightforward synthetic route toward ...substituted tropane derivatives with four contiguous stereocenters. A unique feature of this strategy is the use of readily available isoquinolines to provide two reactive sites for dearomatization, thus opening up an unprecedented approach to tropane derivatives with excellent stereoselectivity. The four‐component reactions proceeded smoothly with good results. Thus, the present method is suitable for the diversity‐oriented synthesis of useful tropane derivatives with high efficiency.
Fab four: A highly stereoselective dearomatizing double Mannich reaction of readily available isoquinolines, which provided two reactive sites for dearomatization, smoothly produced substituted benzotropanes with four contiguous stereocenters. In particular as a four‐component reaction, this transformation shows high potential for the efficient diversity‐oriented synthesis of useful tropane derivatives (see scheme).
Advanced glycation end product (AGE) clearance may cause renal tubular injuries, such as changes in sodium reabsorption. We hypothesize that AGEs interact with sodium metabolism to influence blood ...pressure (BP). The study participants were outpatients who were suspected of having hypertension but had not been treated with antihypertensive medication. Clinic and ambulatory blood pressures were measured at baseline (n = 989) and during follow-up (median, 4.4 years, n = 293). Plasma AGE concentrations were measured by enzyme-linked immunosorbent assay. Twenty-four-hour urine was collected for measurements of creatinine, sodium and lithium. In a cross-sectional analysis (n = 989), subjects in the top quintile versus quintiles 1-4 of plasma AGE concentration had significantly (P ≤ 0.004) lower fractional excretion of lithium (18.3% vs. 21.6%) and fractional distal reabsorption rate of sodium (95.0% vs. 95.8%) but similar BP (P ≥ 0.25). However, there was an interaction between plasma AGE concentration and urinary sodium excretion in relation to diastolic BP (P ≤ 0.058). Only in participants with low urinary sodium chloride excretion (≤6 grams/day, n = 189), clinic (84.3 vs. 80.2 mmHg), 24-h (83.9 vs. 80.4 mmHg), daytime (87.8 vs. 84.8 mmHg) and nighttime (75.1 vs. 72.1 mmHg) diastolic BP at baseline were higher (P ≤ 0.05) in the top quintile than in quintiles 1-4 of plasma AGE concentration. In the longitudinal study (n = 383), similar trends were observed, with significant (P ≤ 0.05) differences in the increment in daytime diastolic BP (6.8 vs. -1.7 mmHg) and incidence of ambulatory and treated hypertension (hazard ratio 3.73) during follow-up. In conclusion, AGEs were associated with high BP, probably via enhanced proximal sodium handling and on low dietary sodium intake.
Methyl carbamate CH3OC(O)NH2 is an isomer of glycine. Quantum chemical analyses show that methyl carbamate is a more stable isomer than glycine. Because of this, there could be a higher chance for ...methyl carbamate to exist in the interstellar medium (ISM) as compared to glycine. Despite immense searches, until now glycine has not been detected in the ISM; therefore, it is worthwhile to search its isomer methyl carbamate. In this paper, we present the constraints of methyl carbamate formation under the interstellar conditions. Large complex organic molecules are favorably produced in hot-corino environments of low-mass protostars. We for the first time carried out astrochemical modeling focusing on the formation of methyl carbamate in physical conditions similar to hot-corino objects. Consequently, we examined ALMA archival data for existing spectral line observations toward hot corinos NGC 1333 IRAS 4A2 and IRAS 16293B. Within the common spectral range toward these sources, we found three features are possibly related to the spectral transitions of methyl carbamate and consequently estimate the upper limit of column densities. Results of chemical modeling are consistent with the observational upper limit of estimated column density/abundance toward the sources. This may hint the validation of the proposed formation mechanism. Future observations using a telescope like ngVLA may confirm the presence of MC toward the hot corinos.
Abstract
Poly(ethylene oxide)-based solid-state electrolytes are widely considered promising candidates for the next generation of lithium and sodium metal batteries. However, several challenges, ...including low oxidation resistance and low cation transference number, hinder poly(ethylene oxide)-based electrolytes for broad applications. To circumvent these issues, here, we propose the design, synthesis and application of a fluoropolymer, i.e., poly(2,2,2-trifluoroethyl methacrylate). This polymer, when introduced into a poly(ethylene oxide)-based solid electrolyte, improves the electrochemical window stability and transference number. Via multiple physicochemical and theoretical characterizations, we identify the presence of tailored supramolecular bonds and peculiar morphological structures as the main factors responsible for the improved electrochemical performances. The polymeric solid electrolyte is also investigated in full lithium and sodium metal lab-scale cells. Interestingly, when tested in a single-layer pouch cell configuration in combination with a Li metal negative electrode and a LiMn
0.6
Fe
0.4
PO
4
-based positive electrode, the polymeric solid-state electrolyte enables 200 cycles at 42 mA·g
−1
and 70 °C with a stable discharge capacity of approximately 2.5 mAh when an external pressure of 0.28 MPa is applied.
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