Model-predictive current control (MPCC) is widely recognized as a high-performance control strategy of permanent magnet synchronous machine (PMSM) drives due to its quick response and simple ...principle. It uses a cost function to select the best voltage vector minimizing the current error between the reference value and the feedback value. However, as only one voltage vector is applied during one control period, it fails to give satisfactory performance due to the limited voltage vectors, especially in the case of two-level converters. This paper proposes an improved MPCC strategy for PMSM drives, which first estimates the back electromotive force (EMF) based on the past value of stator voltage and currents and then applies the estimated EMF in the stator current prediction. To achieve steady-state performance improvement, a null vector along with the active vector obtained from conventional MPCC is applied during one control period. Two methods are proposed to achieve optimal vector selection and vector duration. The first one requires six predictions and the calculation of current differentiation, while the second one only requires one prediction to obtain the best voltage vector and its optimal duty can be obtained in a very efficient way. The proposed methods are comparatively studied and compared to conventional MPCC and deadbeat control with space vector modulation. Both simulation and experimental results confirm the effectiveness of the proposed methods in achieving good steady-state performance while maintaining quick dynamic response.
Organic semiconductors offer a tunable platform for photocatalysis, yet the more difficult exciton dissociation, compared to that in inorganic semiconductors, lowers their photocatalytic activities. ...In this work, we report that the charge carrier lifetime is dramatically prolonged by incorporating a suitable donor-acceptor (β-ketene-cyano) pair into a covalent organic framework nanosheet. These nanosheets show an apparent quantum efficiency up to 82.6% at 450 nm using platinum as co-catalyst for photocatalytic H
evolution. Charge carrier kinetic analysis and femtosecond transient absorption spectroscopy characterizations verify that these modified covalent organic framework nanosheets have intrinsically lower exciton binding energies and longer-lived charge carriers than the corresponding nanosheets without the donor-acceptor unit. This work provides a model for gaining insight into the nature of short-lived active species in polymeric organic photocatalysts.
Solar energy-assisted water oxidative hydrogen peroxide (H2O2) production on an anode combined with H2 production on a cathode increases the value of solar water splitting, but the challenge of the ...dominant oxidative product, O2, needs to be overcome. Here, we report a SnO2–x overlayer coated BiVO4 photoanode, which demonstrates the great ability to near-completely suppress O2 evolution for photoelectrochemical (PEC) H2O oxidative H2O2 evolution. Based on the surface hole accumulation measured by surface photovoltage, downward quasi-hole Fermi energy at the photoanode/electrolyte interface and thermodynamic Gibbs free energy between 2-electron and 4-electron competitive reactions, we are able to consider the photoinduced holes of BiVO4 that migrate to the SnO2–x overlayer kinetically favor H2O2 evolution with great selectivity by reduced band bending. The formation of H2O2 may be mediated by the formation of hydroxyl radicals (OH·), from 1-electron water oxidation reactions, as evidenced by spin-trapping electron paramagnetic resonance (EPR) studies conducted herein. In addition to the H2O oxidative H2O2 evolution from PEC water splitting, the SnO2–x /BiVO4 photoanode can also inhibit H2O2 decomposition into O2 under either electrocatalysis or photocatalysis conditions for continuous H2O2 accumulation. Overall, the SnO2–x /BiVO4 photoanode achieves a Faraday efficiency (FE) of over 86% for H2O2 generation in a wide potential region (0.6–2.1 V vs reversible hydrogen electrode (RHE)) and an H2O2 evolution rate averaging 0.825 μmol/min/cm2 at 1.23 V vs RHE under AM 1.5 illumination, corresponding to a solar to H2O2 efficiency of ∼5.6%; this performance surpasses almost all previous solar energy-assisted H2O2 evolution performances. Because of the simultaneous production of H2O2 and H2 by solar water splitting in the PEC cells, our results highlight a potentially greener and more cost-effective approach for “solar-to-fuel” conversion.
► The intrinsic poor electronic conductivity of layered LiNi
0.5Mn
0.5O
2 cathode material limits its wide application. ► In this study, pure phase, well-crystallized macroporous LiNi
0.5Mn
0.5O
2 ...was prepared by a simple one-step route using gas template. ► The as-synthesized LiNi
0.5Mn
0.5O
2 has much higher first discharge capacity than the material synthesized by conventional solid state reaction method. ► Furthermore, the macroporous LiNi
0.5Mn
0.5O
2 material also possesses remarkable rate capacity and cycle stability.
A simple one-step route using gas template method is applied to synthesize macroporous LiNi
0.5Mn
0.5O
2 which is characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Telle (BET) surface area, charge–discharge tests and electrochemical impedance spectroscopy (EIS) measurements. The as-synthesized material shows pure crystalline phase of LiNi
0.5Mn
0.5O
2, while the microstructure is comprised of macrospores ranging from 0.2 to 0.5
μm. The first discharge capacity is of 174
mAh
g
−1 at 0.1
C rate, which is much higher than that of the material synthesized by the conventional solid state reaction method. Furthermore, the macroporous LiNi
0.5Mn
0.5O
2 material shows remarkable rate capacity and cycle stability, which may be attributed to the shorter lithium ion diffusion distance and better electrolyte penetration.
Previous trial evidence suggested potential risk of serious urinary tract infections (UTIs) and genital infections in type 2 diabetes patients using sodium glucose co-transporter-2 inhibitors (SGLT2) ...inhibitors. We conducted a systematic review and meta-analysis to assess the effects of SGLT2 inhibitors on UTIs and genital infections in patients with type 2 diabetes. In total, 77 RCTs involving 50,820 participants were eligible. The meta-analyses of randomized controlled trials (RCTs) showed no significant difference in UTIs between SGLT2 inhibitors versus control (2,526/29,086 vs. 1,278/14,940; risk ratio (RR) 1.05, 95% confidence interval (CI) 0.98 to 1.12; moderate quality evidence), but suggested increased risk of genital infections with SGLT2 inhibitors (1,521/24,017 vs. 216/12,552; RR 3.30, 95% CI 2.74 to 3.99; moderate quality evidence). Subgroup analyses by length of follow up (interaction p = 0.005), type of control (interaction p = 0.04) and individual SGLT2 inhibitors (interaction p = 0.03) also showed statistically significant differences in genital infections. The upcoming major trials may provide important additional insights on UTIs, and more efforts are needed to address comparative effects of each individual SGLT2 inhibitors on the infections.
Herein, we report the design and fabrication of QH-COF@TiO2 and TiO2@QH-COF (QH-COF: tetrahydroquinoline-linked COFs) core–shell structured heterojunctions for photocatalytic oxidation of alcohols. ...For the first time, the spatial location of two semiconductors either in the core or on the shell is precisely designed, and their corresponding photocatalytic performance has been well investigated. For photocatalytic benzyl alcohol oxidation, the activity of QH-COF@TiO2 is almost three times higher than that of TiO2@QH-COF (reaction rate: 1.19 vs. 0.44 mmol g−1 h−1), although they exhibit similar capability for light harvesting and charge separation. The higher photocatalytic activity of QH-COF@TiO2 is due to its easier donation of electrons to O2. A similar tendency was also observed for the visible-light photocatalytic aerobic cross-dehydrogenative coupling reaction. Our spatial location engineering of semiconductor heterojunctions provides an efficient strategy that facilitates the modulation of charge separation and mass diffusion to enhance the photocatalytic activity of semiconductors.
Promotion of patient safety is among the most important goals and challenges of healthcare systems worldwide in countries including China. Donabedian’s Structure-Process-Outcome model implies that ...patient safety is affected by hospital nursing organizational factors and nursing care process. However, studies are imperative for a clear understanding about the mechanisms by which patient safety is affected to guide practice.
The objective of this study was to explore the impact of hospital nursing work environment, workload, nursing care left undone, and nurse burnout on patient safety.
This was a cross-sectional study conducted in 23 hospitals in Guangdong province, China in 2014. Data from nurses (n = 1542) responsible for direct care on 111 randomly sampled medical and surgical units were analyzed.
Work environment was measured by the Practice Environment Scale of Nursing Work Index. Workload was measured by day shift unit patient-nurse ratio and non-professional tasks conducted by nurses. Nursing care left undone was measured by 12 items addressing necessary nursing activities. Nurse burnout was measured by the emotional exhaustion subscale of the Maslach Burnout Inventory-Human Services Survey. Patient safety was measured by three items indicating nurses’ perception of overall patient safety and nine items addressing patient adverse events. Structural equation modeling was used to examine a hypothesized model that supposed work environment and workload have both direct and indirect effects on patient safety through nursing care left undone and nurse burnout.
The findings generally supported the hypothesized model. Better work environment was associated with better patient safety both directly and indirectly. Lower workload primarily indirectly related to better patient safety. Nursing care left undone and nurse burnout were mediators negatively associated with patient safety.
Improving work environment, increasing nurse staffing levels, and providing sufficient support for nurses to spend more time on direct patient care would be beneficial to patient safety improvement.
Gut-derived bacterial lipopolysaccharide (LPS) and subsequent hepatic toll-like receptor 4 (TLR4) activation have been recognized to be involved in the onset of diet-induced nonalcoholic fatty liver ...disease (NAFLD), but little is known about the variation of LPS and TLR4 during the progression of NAFLD. Probiotics were able to inhibit proliferation of harmful bacteria and improve gastrointestinal barrier function. However, it's unclear whether LPS/TLR4 is involved in the protection effect of probiotics on NAFLD. In this study, we described characteristic of gut microbiota structure in the progression of NAFLD, and we also analyzed the relationship between gut microbiota and LPS/TLR4 in this process. Furthermore, we applied probiotics intervention to investigate the effect of probiotics on gut flora structure, intestinal integrity, serum LPS, liver TLR4 and liver pathology. Our results showed that serum LPS and liver TLR4 were highly increased during progression of NAFLD, with gut flora diversity and gut mircobiological colonization resistance (B/E) declining. Furthermore, probiotics could improve gut microbiota structure and liver pathology. Probiotics could also downregulate serum LPS and liver TLR4. Our results suggested that both gut flora alteration and endotoxemia may be involved in the progression of NAFLD. Probiotics may delay the progression of NAFLD via LPS/TLR4 signaling.
Plant immunity often penalizes growth and yield. The transcription factor Ideal Plant Architecture 1 (IPA1) reduces unproductive tillers and increases grains per panicle, which results in improved ...rice yield. Here we report that higher IPA1 levels enhance immunity. Mechanistically, phosphorylation of IPA1 at amino acid Ser
within its DNA binding domain occurs in response to infection by the fungus
and alters the DNA binding specificity of IPA1. Phosphorylated IPA1 binds to the promoter of the pathogen defense gene
and activates its expression, leading to enhanced disease resistance. IPA1 returns to a nonphosphorylated state within 48 hours after infection, resuming support of the growth needed for high yield. Thus, IPA1 promotes both yield and disease resistance by sustaining a balance between growth and immunity.
A modular approach to azulene building blocks was developed starting from readily available aryl‐substituted cyclopentadiene and ortho‐haloaryl aldehyde by dehydration condensation followed by ...palladium‐catalyzed C−H coupling. It facilitates the synthesis of four nonalternant isomers of pentacene and hexacene, namely, dibenzoe,gazulene, benzo1,2‐f : 5,4‐f′diazulene, benzo1,2‐f : 4,5‐f′diazulene, and naphtho2,3‐f : 6,7‐f′diazulene, which exhibit narrow band gaps with high stability in addition to protonation‐caused enhanced near‐infrared fluorescence. We discovered that in these isomers, i) constitutional isomerism influences significantly their photoelectric properties and ii) the elongation of the conjugation system does not necessarily lead to a narrowing in the band gap. Due to the easy modifiability of the nonazulene building blocks, this strategy can be extended to modularly prepare numerous multiazulene‐fused aromatics.
A modular two‐step 4+3 annulation approach to azulene units was developed starting from readily available aryl‐substituted cyclopentadiene and ortho‐haloaryl aldehyde by dehydration condensation followed by palladium‐catalyzed C−H coupling. It facilitates the syntheses of four nonalternant isomers of pentacene and hexacene including DBA, BDA1, BDA2, and NDA which exhibit narrow band gaps and protonation‐caused enhanced near‐infrared emission.
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