Challenges for commercializing perovskite solar cells Rong, Yaoguang; Hu, Yue; Mei, Anyi ...
Science (American Association for the Advancement of Science),
2018-Sep-21, 2018-09-21, 20180921, Letnik:
361, Številka:
6408
Journal Article
Recenzirano
Perovskite solar cells (PSCs) have witnessed rapidly rising power conversion efficiencies, together with advances in stability and upscaling. Despite these advances, their limited stability and need ...to prove upscaling remain crucial hurdles on the path to commercialization. We summarize recent advances toward commercially viable PSCs and discuss challenges that remain. We expound the development of standardized protocols to distinguish intrinsic and extrinsic degradation factors in perovskites. We review accelerated aging tests in both cells and modules and discuss the prediction of lifetimes on the basis of degradation kinetics. Mature photovoltaic solutions, which have demonstrated excellent long-term stability in field applications, offer the perovskite community valuable insights into clearing the hurdles to commercialization.
Gallium‐based liquid metal (LM) composite with metallic fillers is an emerging class of thermal interface materials (TIMs), which are widely applied in electronics and power systems to improve their ...performance. In situ alloying between gallium and many metallic fillers like copper and silver, however, leads to a deteriorated composite stability. This paper presents an interfacial engineering approach using 3‐chloropropyltriethoxysilane (CPTES) to serve as effective thermal linkers and diffusion barriers at the copper‐gallium oxide interfaces in the LM matrix, achieving an enhancement in both thermal conductivity and stability of the composite. By mixing LM with copper particles modified by CPTES, a thermal conductivity (κ) as high as 65.9 W m−1 K−1 is achieved. In addition, κ can be tuned by altering the terminal groups of silane molecules, demonstrating the flexibility of this approach. The potential use of such composite as a TIM is also shown in the heat dissipation of a computer central processing unit. While most studies on LM‐based composites enhance the material performance via direct mixing of various fillers, this work provides a different approach to fabricate high‐performance LM‐based composites and may further advance their applications in various areas including thermal management systems, flexible electronics, consumer electronics, and biomedical systems.
Liquid metal composite with metallic fillers is a promising class of thermal interface materials. In this work, 3‐chloropropyltriethoxysilane is used to serve as molecular thermal linkers and diffusion barriers at the liquid metal–copper interface. Enhancement in both thermal conductivity and stability of liquid metal–copper composite is achieved using this interfacial engineering approach.
The 2016 definitions of sepsis included the quick Sepsis-related Organ Failure Assessment (qSOFA) score to identify high-risk patients outside the intensive care unit (ICU).
We sought to compare ...qSOFA with other commonly used early warning scores.
All admitted patients who first met the criteria for suspicion of infection in the emergency department (ED) or hospital wards from November 2008 until January 2016 were included. The qSOFA, Systemic Inflammatory Response Syndrome (SIRS), Modified Early Warning Score (MEWS), and the National Early Warning Score (NEWS) were compared for predicting death and ICU transfer.
Of the 30,677 included patients, 1,649 (5.4%) died and 7,385 (24%) experienced the composite outcome (death or ICU transfer). Sixty percent (n = 18,523) first met the suspicion criteria in the ED. Discrimination for in-hospital mortality was highest for NEWS (area under the curve AUC, 0.77; 95% confidence interval CI, 0.76-0.79), followed by MEWS (AUC, 0.73; 95% CI, 0.71-0.74), qSOFA (AUC, 0.69; 95% CI, 0.67-0.70), and SIRS (AUC, 0.65; 95% CI, 0.63-0.66) (P < 0.01 for all pairwise comparisons). Using the highest non-ICU score of patients, ≥2 SIRS had a sensitivity of 91% and specificity of 13% for the composite outcome compared with 54% and 67% for qSOFA ≥2, 59% and 70% for MEWS ≥5, and 67% and 66% for NEWS ≥8, respectively. Most patients met ≥2 SIRS criteria 17 hours before the combined outcome compared with 5 hours for ≥2 and 17 hours for ≥1 qSOFA criteria.
Commonly used early warning scores are more accurate than the qSOFA score for predicting death and ICU transfer in non-ICU patients. These results suggest that the qSOFA score should not replace general early warning scores when risk-stratifying patients with suspected infection.
End-tidal carbon dioxide (EtCO2) is an invaluable anesthesia measure due to minimal delay in monitoring ventilation. Oral and Maxillofacial Surgery (OMS) presents special challenges because oral ...exhalations are not sampled effectively via nasal cannula normally used to avoid interfering with procedures.
The purpose of the study was to compare EtCO2 waveforms obtained in subjects using nasal monitoring and combined nasal and oral monitoring under simulated ventilatory conditions.
A single-blinded, randomized crossover controlled study was conducted at the University of Illinois Chicago with healthy volunteers, who were blinded to the monitoring system used. Inclusion criteria required subjects be >18 years of age, be consentable and English-speaking. Exclusion criteria required no airway abnormalities, no edentulism, no conditions that preclude undergoing an OMS procedure under sedation.
The primary predictor variable was the EtCO2 monitoring system: nasal with a standard nasal cannula, and combined with a nasal cannula and oral device. The secondary predictor variable evaluated three ventilatory states (nasal breathing, oral breathing, apnea) in each arm, standardizing by maintaining consistent breath counts across observation periods.
The main outcome variable was the number of waveforms recorded over 30 seconds for nasal and combined monitoring. Each recording was standardized by dividing it by the baseline waveforms and multiplying by 20. Higher values, closer to baseline, were considered more accurate depictions of ventilation.
Covariates were body mass index (BMI), age, sex, Mallampati score, and breathing method.
ANOVA, ANCOVA, and MANOVA were performed. P-value<0.05 was considered statistically significant.
The sample included 25 subjects (18 male, 7 female) with mean age 29.9+7.98 years and BMI 23.9+3.51 kg/m2. Combined sampling detected more waveforms during nasal and oral breathing (p<0.001). Higher BMI correlated with reduced waveform capture during nasal sampling in oral breathing (p=0.013). Combined sampling detected more waveforms during nasal breathing (p=0.005) in subjects with BMI < 23.5 kg/m2. Mallampati score correlated with increased waveforms during nasal breathing.
Oral EtCO2 sampling may improve accuracy of capnography waveform capture. Further clinical studies in sedated subjects undergoing OMS procedures are needed.
A systematic interrogation of male germ cells is key to complete understanding of molecular mechanisms governing spermatogenesis and the development of new strategies for infertility therapies and ...male contraception. Here we develop an approach to purify all types of homogeneous spermatogenic cells by combining transgenic labeling and synchronization of the cycle of the seminiferous epithelium, and subsequent single-cell RNA-sequencing. We reveal extensive and previously uncharacterized dynamic processes and molecular signatures in gene expression, as well as specific patterns of alternative splicing, and novel regulators for specific stages of male germ cell development. Our transcriptomics analyses led us to discover discriminative markers for isolating round spermatids at specific stages, and different embryo developmental potentials between early and late stage spermatids, providing evidence that maturation of round spermatids impacts on embryo development. This work provides valuable insights into mammalian spermatogenesis, and a comprehensive resource for future studies towards the complete elucidation of gametogenesis.
Identification of genetic factors that interact with the apolipoprotein e4 (APOE4) allele to reduce risk for Alzheimer disease (AD) would accelerate the search for new AD drug targets. Klotho-VS ...heterozygosity (KL-VSHET+ status) protects against aging-associated phenotypes and cognitive decline, but whether it protects individuals who carry APOE4 from AD remains unclear.
To determine if KL-VSHET+ status is associated with reduced AD risk and β-amyloid (Aβ) pathology in individuals who carry APOE4.
This study combined 25 independent case-control, family-based, and longitudinal AD cohorts that recruited referred and volunteer participants and made data available through public repositories. Analyses were stratified by APOE4 status. Three cohorts were used to evaluate conversion risk, 1 provided longitudinal measures of Aβ CSF and PET, and 3 provided cross-sectional measures of Aβ CSF. Genetic data were available from high-density single-nucleotide variant microarrays. All data were collected between September 2015 and September 2019 and analyzed between April 2019 and December 2019.
The risk of AD was evaluated through logistic regression analyses under a case-control design. The risk of conversion to mild cognitive impairment (MCI) or AD was evaluated through competing risks regression. Associations with Aβ, measured from cerebrospinal fluid (CSF) or brain positron emission tomography (PET), were evaluated using linear regression and mixed-effects modeling.
Of 36 530 eligible participants, 13 782 were excluded for analysis exclusion criteria or refusal to participate. Participants were men and women aged 60 years and older who were non-Hispanic and of Northwestern European ancestry and had been diagnosed as being cognitively normal or having MCI or AD. The sample included 20 928 participants in case-control studies, 3008 in conversion studies, 556 in Aβ CSF regression analyses, and 251 in PET regression analyses. The genotype KL-VSHET+ was associated with reduced risk for AD in individuals carrying APOE4 who were 60 years or older (odds ratio, 0.75 95% CI, 0.67-0.84; P = 7.4 × 10-7), and this was more prominent at ages 60 to 80 years (odds ratio, 0.69 95% CI, 0.61-0.79; P = 3.6 × 10-8). Additionally, control participants carrying APOE4 with KL-VS heterozygosity were at reduced risk of converting to MCI or AD (hazard ratio, 0.64 95% CI, 0.44-0.94; P = .02). Finally, in control participants who carried APOE4 and were aged 60 to 80 years, KL-VS heterozygosity was associated with higher Aβ in CSF (β, 0.06 95% CI, 0.01-0.10; P = .03) and lower Aβ on PET scans (β, -0.04 95% CI, -0.07 to -0.00; P = .04).
The genotype KL-VSHET+ is associated with reduced AD risk and Aβ burden in individuals who are aged 60 to 80 years, cognitively normal, and carrying APOE4. Molecular pathways associated with KL merit exploration for novel AD drug targets. The KL-VS genotype should be considered in conjunction with the APOE genotype to refine AD prediction models used in clinical trial enrichment and personalized genetic counseling.
•Present a critical review on co-simulation of building energy systems and indoor environment for energy and control related applications.•Review methods for co-simulation, including exchanged data, ...data synchronization schemes, and software realization.•Review current and potential applications using co-simulation and identify future research needs on coupling building energy simulation (BES) and Computational Fluid Dynamics (CFD).
This paper presents a comprehensive review of the open literature on motivations, methods and applications of linking stratified airflow simulation to building energy simulation (BES). First, we reviewed the motivations for coupling prediction models for building energy and indoor environment. This review classified various exchanged data in different applications as interface data and state data, and found that choosing different data sets may lead to varying performance of stability, convergence, and speed for the co-simulation. Second, our review shows that an external coupling scheme is substantially more popular in implementations of co-simulation than an internal coupling scheme. The external coupling is shown to be generally faster in computational speed, as well as easier to implement, maintain and expand than the internal coupling. Third, the external coupling can be carried out in different data synchronization schemes, including static coupling and dynamic coupling. In comparison, the static coupling that performs data exchange only once is computationally faster and more stable than the dynamic coupling. However, concerning accuracy, the dynamic coupling that requires multiple times of data exchange is more accurate than the static coupling. Furthermore, the review identified that the implementation of the external coupling can be achieved through customized interfaces, middleware, and standard interfaces. The customized interface is straightforward but may be limited to a specific coupling application. The middleware is versatile and user-friendly but usually limited in data synchronization schemes. The standard interface is versatile and promising, but may be difficult to implement. Current applications of the co-simulation are mainly energy performance evaluation and control studies. Finally, we discussed the limitations of the current research and provided an overview for future research.
The diagnostic accuracy of computer detection programs has been reported to be comparable to that of specialists and expert readers, but no computer detection programs have been validated in an ...independent cohort using an internationally recognized diabetic retinopathy (DR) standard.
To determine the sensitivity and specificity of the Iowa Detection Program (IDP) to detect referable diabetic retinopathy (RDR).
In primary care DR clinics in France, from January 1, 2005, through December 31, 2010, patients were photographed consecutively, and retinal color images were graded for retinopathy severity according to the International Clinical Diabetic Retinopathy scale and macular edema by 3 masked independent retinal specialists and regraded with adjudication until consensus. The IDP analyzed the same images at a predetermined and fixed set point. We defined RDR as more than mild nonproliferative retinopathy and/or macular edema.
A total of 874 people with diabetes at risk for DR.
Sensitivity and specificity of the IDP to detect RDR, area under the receiver operating characteristic curve, sensitivity and specificity of the retinal specialists' readings, and mean interobserver difference (κ).
The RDR prevalence was 21.7% (95% CI, 19.0%-24.5%). The IDP sensitivity was 96.8% (95% CI, 94.4%-99.3%) and specificity was 59.4% (95% CI, 55.7%-63.0%), corresponding to 6 of 874 false-negative results (none met treatment criteria). The area under the receiver operating characteristic curve was 0.937 (95% CI, 0.916-0.959). Before adjudication and consensus, the sensitivity/specificity of the retinal specialists were 0.80/0.98, 0.71/1.00, and 0.91/0.95, and the mean intergrader κ was 0.822.
The IDP has high sensitivity and specificity to detect RDR. Computer analysis of retinal photographs for DR and automated detection of RDR can be implemented safely into the DR screening pipeline, potentially improving access to screening and health care productivity and reducing visual loss through early treatment.
Segmental maxillary osteotomies require precise occlusal control due to variability in individual segment positioning. The role of maxillomandibular fixation (MMF) technique on occlusal control has ...not been validated.
The purpose is to measure and compare the accuracy of occlusal positioning among MMF techniques.
This was a double-blinded in vitro study on experiment models to simulate a 3-piece LeFort I osteotomy. The models were constricted posteriorly and expanded using 3 different MMF techniques and compared to the unaltered baseline occlusion. Based on sample size calculation, 32 separate attempts were made for each MMF technique.
The predictor variable was MMF technique (brackets, MMF screws, and embrasure wires).
The primary outcome variable was the visual occlusal analysis score, a 1.00 to 4.00 continuous scale measuring the similarity of the achieved occlusion to the planned (control) occlusion assessed by an oral and maxillofacial surgeon and an orthodontist. High visual occlusal analysis score indicated greater occlusal accuracy, with 3.50 defined as the threshold for accuracy. The secondary outcome variable was the linear error of the achieved occlusion at the canine and first molar teeth, with lower error indicating greater accuracy. An a priori accuracy threshold of 0.5 mm was set for this variable.
None.
Kruskal-Wallis test with post hoc testing was used to analyze the difference in the outcome variables of interest. P value < .05 was considered statistically significant.
Thirty-two attempts for each technique showed that brackets had higher VAOS than MMF screws and embrasure wires (median differences 1.49 and 0.48, P < .001), and had lower linear occlusal error (median differences 0.35 to 0.99 mm, P < .001).
MMF technique influences the quality of occlusal control, with greater visual rating scores and lower linear errors seen with brackets than with embrasure wires or MMF screws.
Due to its simple process and low energy consumption, forward osmosis (FO) has gained significant attention in the fields of portable hydration bags, desalination, landfill leachate treatment, and ...brine concentration. However, current state-of-the-art reverse osmosis (RO) membranes show relatively low water fluxes in FO processes due to high internal concentration polarization (ICP) and high mass transfer resistance in commercially available microporous support membranes. In this study, carboxylated polysulfones (CPSFs) were synthesized via direct polysulfone (PSF) functionalization and considered as hydrophilic, mechanically stable microporous support membranes. The incorporation of hydrophilic groups into hydrophobic polymer backbones often reduces mechanical strength due to excessive water swelling. However, the mechanical properties of CPSFs (degree of substitution, DS=0.49–0.85) were similar to those of pristine PSF, and they retained their hydrophilic nature. Microporous CPSF membranes were prepared in various conditions, and FO water fluxes and salt passages of polyamide thin-film/CPSF composite membranes were measured and compared with each other. CPSF-based FO membranes showed significantly higher water fluxes (water flux in FO mode: 18L/m2h, salt passage: 2.2g/m2h under 1M MgCl2 as a draw solution, active layer facing DI water) than PSF-based FO membranes (10.5L/m2h, 1.5g/m2h at the same conditions), which might be due to enhanced hydrophilicity and reduced ICP.
•Carboxylated polysulfone membranes were prepared as promising support layers for FO membranes.•CPSF membranes showed moderate hydrophilicity and stable membrane structures.•PA-CPSF TFC membranes showed higher FO water flux than pristine PA-PSF TFC membranes.
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