Display omitted
•The indirect Z-scheme g-C3N4-RGO-TiO2 photocatalysts were successfully fabricated.•A 3.2-fold activity enhancement was achieved by inserting RGO into g-C3N4- TiO2.•The indirect ...Z-scheme mechanism was verified by PL spectra and radical trapping.•The multi-functional roles of RGO in enhancing photodegradation were revealed.
In the present research work, the ternary indirect all-solid-state Z-scheme nanoheterojunctions, graphitic-C3N4/reduced graphene oxide/anatase TiO2 (g-C3N4-RGO-TiO2) with highly enhanced photocatalytic performance were successfully prepared via a simple liquid-precipitation strategy. The photocatalytic activities of indirect all-solid-state Z-scheme g-C3N4-RGO-TiO2 nanoheterojunctions were evaluated by the degradation of methylene blue (MB). The results showed that the introduction of RGO as an interfacial mediator into direct Z-scheme g-C3N4-TiO2 nanocomposites can remarkably enhance their photocatalytic activities. The as-obtained indirect all-solid-state Z-scheme g-C3N4-RGO-TiO2 nanoheterojunctions, with the optimal loading amount of 10wt% RGO, exhibited the highest rate towards the photocatalytic degradation of MB under simulated solar light irradiation. The degradation kinetics of MB can be described by the apparent first-order kinetics model. The highest degradation rate constant of 0.0137min−1 is about 4.7 and 3.2 times greater than those of the pure g-C3N4 (0.0029min−1) and direct Z-scheme g-C3N4-TiO2 (0.0043min−1), respectively. An indirect all-solid-state Z-scheme charge-separation mechanism was proposed based on the photoluminescence spectra and the trapping experiment procedure of the photo-generated active species. It was believed that the indirect all-solid-state Z-scheme charge separation mechanism in g-C3N4-RGO-TiO2 nanoheterojunctions could lead to the promoted charge separation and transfer, improved oxygen-reduction capacity of electrons in g-C3N4 and the formation of hydroxyl radicals driven by the holes in TiO2, respectively, thus achieving the highly enhanced photocatalytic degradation performance. This work might provide new insights and understanding on the graphene as electron mediators to design highly efficient all-solid-state Z-scheme nanoheterojunctions with enhanced visible-light driven photoactivity for various photocatalytic applications.
The widespread presence of antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB) in the drinking water system facilitates their horizontal gene transfer among microbiota. In this ...study, the conjugative gene transfer of RP4 plasmid after disinfection including ultraviolet (UV) irradiation and low-level chlorine treatment was investigated. It was found that both UV irradiation and low-level chlorine treatment reduced the conjugative gene transfer frequency. The transfer frequency gradually decreased from 2.75 × 10−3 to 2.44 × 10−5 after exposure to UV doses ranging from 5 to 20 mJ/cm2. With higher UV dose of 50 and 100 mJ/cm2, the transfer frequency was reduced to 1.77 × 10−6 and 2.44 × 10−8. The RP4 plasmid transfer frequency was not significantly affected by chlorine treatment at dosages ranging from 0.05 to 0.2 mg/l, but treatment with 0.3–0.5 mg/l chlorine induced a decrease in conjugative transfer to 4.40 × 10−5 or below the detection limit. The mechanisms underlying these phenomena were also explored, and the results demonstrated that UV irradiation and chlorine treatment (0.3 and 0.5 mg/l) significantly reduced the viability of bacteria, thereby lowering the conjugative transfer frequency. Although the lower chlorine concentrations tested (0.05–0.2 mg/l) were not sufficient to damage the cells, exposure to these concentrations may still depress the expression of a flagellar gene (FlgC), an outer membrane porin gene (ompF), and a DNA transport-related gene (TraG). Additionally, fewer pili were scattered on the bacteria after chlorine treatment. These findings are important in assessing and controlling the risk of ARG transfer and dissemination in the drinking water system.
Display omitted
•UV irradiation and low-level of chlorine treatment reduced conjugative transfer.•UV irradiation decreased the alive donors, thus lowered their conjugative transfer.•0.3 and 0.5 mg/l chlorine lowered conjugative transfer by reducing bacterial cells.•Low-level chlorine depressed the expression of FlgC, ompF, and TraG.•Fewer pili scattered around the bacteria after chlorine treatment.
Mutations in amyloid β precursor protein (APP) gene alter APP processing, either causing familial Alzheimer's disease (AD) or protecting against dementia. Under normal conditions, β-site APP cleaving ...enzyme 1 (BACE1) cleaves APP at minor Asp
site to generate C99 for amyloid β protein (Aβ) production, and predominantly at major Glu
site to generate C89, resulting in truncated Aβ production. We discovered that A673V mutation, the only recessive AD-associated APP mutation, shifted the preferential β-cleavage site of BACE1 in APP from the Glu
site to the Asp
site both in male and female transgenic mice
and in cell lines and primary neuronal culture derived from timed pregnant rats
, resulting in a much higher C99 level and C99/C89 ratio. All other mutations at this site, including the protective Icelandic A673T mutation, reduced C99 generation, and decreased the C99/C89 ratio. Furthermore, A673V mutation caused stronger dimerization between mutant and wild-type APP, enhanced the lysosomal degradation of the mutant APP, and inhibited γ-secretase cleavage of the mutant C99 to generate Aβ, leading to recessively inherited AD. The results demonstrate that APP673 regulates APP processing and the BACE1 cleavage site selection is critical for amyloidogenesis in AD pathogenesis, and implicate a pharmaceutical potential for targeting the APP673 site for AD drug development.
β-site APP cleaving enzyme 1 (BACE1) is essential for amyloid β protein production. We discovered that A673V mutation shifted the BACE1 cleavage site from the Glu
to the Asp
site, resulting in much higher C99 level and C99/C89 ratio. All other mutations at this site of amyloid β precursor protein (APP) reduced C99 generation and decreased the C99/C89 ratio. Furthermore, A673V mutation resulted in stronger dimerization between mutant and wild-type APP, enhanced the lysosomal degradation of the mutant APP, and inhibited γ-secretase cleavage of the mutant C99 to generate amyloid β protein, leading to recessively inherited Alzheimer's disease (AD). The results demonstrate that APP673 regulates APP processing, and the BACE1 cleavage site selection is critical for amyloidogenesis in AD pathogenesis, and implicate a pharmaceutical potential for targeting the APP673 site for AD drug development.
With over 2 million new cases annually, stroke is associated with the highest disability-adjusted life-years lost of any disease in China. The burden is expected to increase further as a result of ...population ageing, an ongoing high prevalence of risk factors (eg, hypertension), and inadequate management. Despite improved access to overall health services, the availability of specialist stroke care is variable across the country, and especially uneven in rural areas. In-hospital outcomes have improved because of a greater availability of reperfusion therapies and supportive care, but adherence to secondary prevention strategies and long-term care are inadequate. Thrombolysis and stroke units are accepted as standards of care across the world, including in China, but bleeding-risk concerns and organisational challenges hamper widespread adoption of this care in China. Despite little supporting evidence, Chinese herbal products and neuroprotective drugs are widely used, and the increased availability of neuroimaging techniques also results in overdiagnosis and overtreatment of so-called silent stroke. Future efforts should focus on providing more balanced availability of specialised stroke services across the country, enhancing evidence-based practice, and encouraging greater translational research to improve outcome of patients with stroke.
Efficiency roll-off is a major issue for most types of light-emitting diodes (LEDs), and its origins remain controversial. Here we present investigations of the efficiency roll-off in perovskite LEDs ...based on two-dimensional layered perovskites. By simultaneously measuring electroluminescence and photoluminescence on a working device, supported by transient photoluminescence decay measurements, we conclude that the efficiency roll-off in perovskite LEDs is mainly due to luminescence quenching which is likely caused by non-radiative Auger recombination. This detrimental effect can be suppressed by increasing the width of quantum wells, which can be easily realized in the layered perovskites by tuning the ratio of large and small organic cations in the precursor solution. This approach leads to the realization of a perovskite LED with a record external quantum efficiency of 12.7%, and the efficiency remains to be high, at approximately 10%, under a high current density of 500 mA cm
.
An important regulator of innate immunity, the protein complex of Toll‐like receptors 1 and 2 (TLR1/TLR2) provides an attractive target for the treatment of various immune disorders. The novel ...compound CU‐CPT22 can compete with the binding of the specific lipoprotein ligand to TLR1/TLR2 (see picture) with high inhibitory activity and specificity. Repression of downstream signaling from TNF‐α and IL‐1β was also observed.
Deposition of amyloid β protein (Aβ) to form neuritic plaques in the brain is the pathological hallmark of Alzheimer's disease (AD). Aβ is produced by β- and γ-cleavages of amyloid β precursor ...protein (APP). Ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) is a de-ubiquitinating enzyme that cleaves ubiquitin at its carboxyl terminal. Dysfunction of UCHL1 has been reported in neurodegenerative diseases. However, whether UCHL1 affects Aβ production and AD progression remains unknown. Here we report that UCHL1 interacts with APP and regulates Aβ production. UCHL1 increases free ubiquitin level and accelerates the lysosomal degradation of APP by promoting its ubiquitination. Furthermore, we demonstrate that overexpression of UCHL1 by intracranial injection of UCHL1-expressing rAAV reduces Aβ production, inhibits neuritic plaque formation and improves memory deficits in AD transgenic model mice. Our study suggests that UCHL1 may delay Alzheimer's progression by regulating APP degradation in a long-term fashion, and that overexpression of UCHL1 may be a safe and effective disease-modifying strategy to treat AD.
A novel electrochemical system was proposed to remove hardness species, by combining the conventional electrocoagulation process and electrochemical precipitation process. The results showed that the ...new system had excellent synergistic effects. The little amount of Al floc produced in electrocoagulation cell enhanced the hardness removed by floc in electrochemical precipitation cell by 224.65% which increased the total hardness removal in the electrochemical precipitation cell by 69.16%. Meanwhile, the amount of deposit on the cathode surface in electrochemical precipitation cell was decreased by 22.79%, which would delay the cathode inactivation in practical application. The operating cost of the new combined electrochemical system was reduced by 53.09% than that of the conventional electrochemical precipitation process. And the production of sludge was nearly three times decreased in the new system than that in the conventional electrocoagulation process, for the lower current density. Therefore, this new proposed system is a beneficial technology for hardness reduction, which can overcome the drawbacks of the two conventional processes.
The mechanism of the novel combined electrochemical system for hardness removal. Display omitted
•A novel concept of electrochemical system was established for hardness removal.•The total hardness removal was increased for the large improvement of floc removal.•The new system had lower operating cost than electrochemical precipitation process.•The new system produced less sludge than electrocoagulation process.
Aiming at the problems of low fault diagnosis accuracy caused by insufficient samples and unbalanced data sample distribution in bearing fault diagnosis, this paper proposes a fault diagnosis method ...for rolling bearings referencing conditional deep convolution adversarial generative networks (C−DCGAN) for efficient data augmentation. Firstly, the concept of conditional constraints is used to guide and improve the sample generation process of the original generative adversarial network, and specific constraints are added to the data generation model to perform a balanced expansion of muti-category fault data for small sample data sets. Secondly, aiming at the phenomena of training instability, gradient disappearance and gradient explosion in the imbalanced sample set, it is proposed to optimize the structure of the generative network by using the structure of self-defined skip connections and spectral normalization, while using the Wasserstein distance with penalty term instead of cross entropy. The function is used as the loss function of the generative adversarial network to improve the stable feature extraction ability of the generative network and the effect of the training process; in this way, simulation sample data with only a small variation from the real data distribution can be generated. Finally, the complete fault data set (after mixing the original data with sufficient fault category and sample number) and the generated data are input into the one-dimensional convolution neural network for fault diagnosis of rolling bearing. The experiment’s results show that the diagnosis method in this paper can improve the fault classification effect of rolling bearings by generating balanced and sufficient sample data.
PDF
