Thin-film dye-sensitized solar cells (DSCs) based on mesoporous semiconductor electrodes are low-cost alternatives to conventional silicon devices. High-efficiency DSCs typically operate as ...photoanodes (n-DSCs), where photocurrents result from dye-sensitized electron injection into n-type semiconductors. Dye-sensitized photocathodes (p-DSCs) operate in an inverse mode, where dye-excitation is followed by rapid electron transfer from a p-type semiconductor to the dye (dye-sensitized hole injection). Such p-DSCs and n-DSCs can be combined to construct tandem solar cells (pn-DSCs) with a theoretical efficiency limitation well beyond that of single-junction DSCs (ref. 4). Nevertheless, the efficiencies of such tandem pn-DSCs have so far been hampered by the poor performance of the available p-DSCs (refs 3, 5-15). Here we show for the first time that p-DSCs can convert absorbed photons to electrons with yields of up to 96%, resulting in a sevenfold increase in energy conversion efficiency compared with previously reported photocathodes. The donor-acceptor dyes, studied as photocathodic sensitizers, comprise a variable-length oligothiophene bridge, which provides control over the spatial separation of the photogenerated charge carriers. As a result, charge recombination is decelerated by several orders of magnitude and tandem pn-DSCs can be constructed that exceed the efficiency of their individual components.
The microstructure and mechanical properties of the CoCrCuFeNiNb high-entropy alloy coating prepared by plasma transferred arc cladding process were investigated. Two phases are found in the prepared ...coating with Nb: one is face-centered-cubic solid solution phase; the other is the Laves phase of (CoCr) Nb type. The nano-indentation testing indicates that the microhardness (H), elastic modulus (E), the hardness/modulus of elasticity ratio (H/E ratio) and high resistance to plastic deformation (H3/E2) of the coating with Nb are 6.13GPa, 221GPa, 0.028 and 4.7×10−3 respectively. The CoCrCuFeNiNb coating displays excellent wear and corrosion resistance. The wear resistance of the coating with Nb is about 1.5 times higher than that of the coating without Nb under the same wet sand rubber wheel abrasion testing conditions. Compared with the coating without Nb and as-cast 304 stainless steel, the coating with Nb shows the lowest icorr values in polarization curves and the highest fitted Rf values in EIS plots in 6N hydrochloric acid solution.
•The CoCrCuFeNiNb HEA coating was prepared by PTA cladding process.•The Nb-free coating was also studied as a comparison material.•Nano-indention was used to investigate mechanical properties of the coating.•The coating has better wear and corrosion resistance than that of Nb-free coating.
The area of thin-film photovoltaics has been overwhelmed by organometal halide perovskites. Unfortunately, serious stability concerns arise with perovskite solar cells. For example, methyl-ammonium ...lead iodide is known to decompose in the presence of water and, more severely, even under inert conditions at elevated temperatures. Here, we demonstrate inverted perovskite solar cells, in which the decomposition of the perovskite is significantly mitigated even at elevated temperatures. Specifically, we introduce a bilayered electron-extraction interlayer consisting of aluminium-doped zinc oxide and tin oxide. We evidence tin oxide grown by atomic layer deposition does form an outstandingly dense gas permeation barrier that effectively hinders the ingress of moisture towards the perovskite and-more importantly-it prevents the egress of decomposition products of the perovskite. Thereby, the overall decomposition of the perovskite is significantly suppressed, leading to an outstanding device stability.
Hierarchical macro‐/mesoporous titania is prepared without the addition of templates or auxiliary additives at room temperature by the simple dropwise addition of tetrabutyl titanate to pure water, ...and then calcined at various temperatures. The products are characterized by X‐ray diffraction, N2‐adsorption–desorption analysis, scanning electron microscopy, and the corresponding photocatalytic activity is evaluated by measuring the photocatalytic oxidation of acetone in air. The results reveal that hierarchical macro‐/mesoporous structures of titania can spontaneously form by self‐assembly in alkoxide–water solutions in the absence of organic templates or auxiliary additives. The calcination temperature has a strong effect on the structures and photocatalytic activity of the prepared titania. At 300 °C, the calcined sample shows the highest photocatalytic activity. At 400 and 500 °C, the photocatalytic activity slightly decreases. When the calcination temperature is higher than 500 °C, the photocatalytic activity greatly decreases because of the destruction of the hierarchical macro‐/mesoporous structure of the titania and the drastic decrease of specific surface area. The hierarchically macro‐/mesostructured titania network with open and accessible pores is well‐preserved after calcination at 500 °C, indicating especially high thermal stability. The macroporous channel structures are even preserved after calcination at 800 °C. This hierarchical macro‐/mesostructured titania is significant because of its potential applications in photocatalysis, catalysis, solar‐cell, separation, and purification processes.
Hierarchical macro‐/mesoporous titania (see figure) was prepared without the addition of templates or auxiliary additives at room temperature by the simple dropwise addition of tetrabutyl titanate to pure water. The calcined samples showed especially high thermal stability and photocatalytic activity, and could be used in photocatalysis, catalysis, solar‐cell, separation, and purification processes.
Most cases of coronavirus disease 2019 (COVID-19) are identified as moderate, which is defined as having a fever or dry cough and lung imaging with ground-glass opacities. The risk factors and ...predictors of prognosis in such cohorts remain uncertain.
All adults with COVID-19 of moderate severity diagnosed using quantitative RT-PCR and hospitalized at the Central Hospital of Wuhan, China, from 1 January to 20 March 2020 were enrolled in this retrospective study. The main outcomes were progression from moderate to severe or critical condition or death.
Among the 456 enrolled patients with moderate COVID-19, 251/456 (55.0%) had poor prognosis. Multivariate logistic regression analysis identified higher neutrophil count: lymphocyte count ratio (NLR) on admission (OR 1.032, 95% CI 1.042–1.230, p 0.004) and higher C-reactive protein (CRP) on admission (OR 3.017, 95% CI 1.941–4.690, p < 0.001) were associated with increased OR of poor prognosis. The area under the receiver operating characteristic curve (AUC) for NLR and CRP in predicting progression to critical condition was 0.77 (95% CI 0.694–0.846, p < 0.001) and 0.84 (95% CI 0.780–0.905, p < 0.001), with a cut-off value of 2.79 and 25.95 mg/L, respectively. The AUC of NLR and CRP in predicting death was 0.81 (95% CI 0.732–0.878, p < 0.001) and 0.89 (95% CI 0.825–0.946, p < 0.001), with a cut-off value of 3.19 and 33.4 mg/L, respectively.
Higher levels of NLR and CRP at admission were associated with poor prognosis of individuals with moderate COVID-19. NLR and CRP were good predictors of progression to critical condition and death.
Introduction
Opioid agonist therapies are effective medications that can greatly improve the quality of life of individuals with opioid use disorder. However, there is significant uncertainty about ...the risks of cause‐specific mortality in and out of treatment.
Objective
This systematic review and meta‐analysis explored the association between methadone and buprenorphine with cause‐specific mortality among opioid‐dependent persons.
Methods
We searched six online databases to identify relevant cohort studies, calculating all‐cause and overdose‐specific mortality rates during periods in and out of treatment. We pooled mortality estimates using multivariate random effects meta‐analysis of the crude mortality rate per 1000 person‐years of follow‐up as well as relative risks comparing mortality in vs. out of treatment.
Results
A total of 32 cohort studies (representing 150 235 participants, 805 423.6 person‐years, and 9112 deaths) met eligibility criteria. Crude mortality rates were substantially higher among methadone cohorts than buprenorphine cohorts. Relative risk reduction was substantially higher with methadone relative to buprenorphine when time in‐treatment was compared to time out‐of‐treatment. Furthermore, the greatest mortality reduction was conferred during the first 4 weeks of treatment. Mortality estimates were substantially heterogeneous and varied significantly by country, region, and by the nature of the treatment provider.
Conclusion
Precautions are necessary for the safer implementation of opioid agonist therapy, including baseline assessments of opioid tolerance, ongoing monitoring during the induction period, education of patients about the risk of overdose, and coordination within healthcare services.
N-graphene synthesized in astrochemical ices Sivaraman, B.; Rahul, K. K.; Ambresh, M. ...
The European physical journal. D, Atomic, molecular, and optical physics,
02/2023, Letnik:
77, Številka:
2
Journal Article
Recenzirano
Odprti dostop
In our quest for the presence of large complex molecules containing a majority of carbon in the interstellar medium (ISM), the search for graphene plays a central role due to its nature in making ...other carbon structures. Although the ingredients for graphene synthesis are present in the ISM, conclusive laboratory evidence of such formation is lacking. Therefore, in our laboratory experiments simulating the cold ISM conditions, we subjected icy mantles of benzonitrile, an aromatic with a cyanide side chain that has recently been detected in the interstellar medium, to vacuum ultraviolet photon irradiation. The irradiated ice was observed to leave a residue upon warming to room temperature. The residue was removed from the substrate and placed on a Quantifoil grid for electron microscopy analysis. Transmission electron microscopy showed quantum dots (QD) and nitrogen-doped graphene (N-Graphene) sheets. Diffraction and energy-dispersive X-ray spectroscopy revealed the crystalline nature and carbon–nitrogen composition, of the observed graphene sheet. This is the first evidence of QD and N-graphene synthesis in ice irradiation at interstellar temperatures.
Graphic Abstract
Increasing evidence has revealed a significant association between microorganisms and oral squamous cell carcinoma (OSCC). Porphyromonas gingivalis, the keystone pathogen in chronic periodontitis, is ...considered an important potential etiologic agent of OSCC, but the underlying immune mechanisms through which P. gingivalis mediates tumor progression of the oral cancer remain poorly understood. Our cohort study showed that the localization of P. gingivalis in tumor tissues was related to poor survival of patients with OSCC. Moreover, P. gingivalis infection increased oral lesion multiplicity and size and promoted tumor progression in a 4-nitroquinoline-1 oxide (4NQO)–induced carcinogenesis mouse model by invading the oral lesions. In addition, CD11b+ myeloid cells and myeloid-derived suppressor cells (MDSCs) showed increased infiltration of oral lesions. Furthermore, in vitro observations showed that MDSCs accumulated when human-derived dysplastic oral keratinocytes (DOKs) were exposed to P. gingivalis, and CXCL2, CCL2, interleukin (IL)–6, and IL-8 may be potential candidate genes that facilitate the recruitment of MDSCs. Taken together, our findings suggest that P. gingivalis promotes tumor progression by generating a cancer-promoting microenvironment, indicating a close relationship among P. gingivalis, tumor progression of the oral cancer, and immune responses.
The results of diffusion-weighted MR imaging (DW-MRI) in predicting early response to chemoradiotherapy in patients with esophageal cancer varied in different studies. We performed this meta-analysis ...to evaluate the predictive values of DW-MRI and compare the diagnostic efficacy of different apparent diffusion coefficients (ADCs). A comprehensive literature search was performed to identify relevant articles published before November 2017. The quality of study was assessed using Quality Assessment of Diagnostic Accuracy Studies-2. The pooled sensitivity, specificity, diagnostic odds ratio (DOR), and area under receiver operating characteristic curve of ADC values were calculated to determine the diagnostic performance. Seven studies with a total of 236 patients were included. The pooled sensitivity, specificity, DOR, and area under curve were 93% (95% CI 77%-98%), 85% (95% CI 72%-93%), 78 (95% CI 15-401), and 0.91 (95% CI 0.89-0.94), respectively, for the ▵ADC; and 75% (95% CI 62%-84%), 90% (95% CI 67%-97%), 26 (95% CI 6-110), and 0.85 (95% CI 0.82-0.88), respectively, for the post-ADC. For pre-ADC, meta-analysis was not performed because of conflicting results. In conclusions, our results demonstrate that DW-MRI has good performance for evaluating the response to chemoradiation therapy in patients with esophageal cancer. ▵ADC and post-ADC are promising reliable and valuable predictors.
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