关键词： Materials Science   general   Characterization and Evaluation of Materials   Polymer Sciences   Solid Mechanics   Crystallography and Scattering Methods   Classical Mechanics  

摘要： Two-dimensional (2D) organic-inorganic perovskite hybrid materials with enhanced stability have attracted wide attention in optoelectronic field in recent years. Efforts of exploring new 2D perovskites with various organic or inorganic components have been devoted to further improve their solar cell efficiencies. In this work, three structurally similar spacer cations of phenylethylammonium (PEA), 4-bromophenylethylammonium (BPEA) and 4-chlorophenylethylammonium (CPEA) are selected to prepare multilayered 2D perovskites. It is found that the introduction of halogen atoms in the organic cations positively influences the film quality, light absorption, charge transport, device performance and moisture stability of the resulting perovskites. The (BPEA)(2)(MA)(4)Pb5I16 and (CPEA)(2)(MA)(4)Pb5I16 perovskites exhibit efficiencies of 7.38% and 10.88%, respectively, which are much higher than that of (PEA)(2)(MA)(4)Pb5I16 (3.98%). Owning to the larger size and bigger electronegativity of halogen atom in spacer cations, the PCE of unsealed BPEA- and CPEA-based 2D perovskite devices maintains 73% and 63% of their original efficiency after 720 h exposure to 60% humid air, while the PEA-based 2D device decreases to 52% of its initial PCE. Our work demonstrates new insight to modify the quality and stability of 2D perovskite hybrids, highlighting the validity of molecule design of organic cations in improving the efficiency and stability of 2D perovskite solar cells.

关键词： alternative calcium   bioactive compounds   pre-treated cuttlebone powder  

摘要： This study was aimed to investigate the potential use of pre-treated cuttlebone powder (CBP) as an alternative calcium source by evaluating the physicochemical properties of CBP pre-treated with distilled water (CBP1), 1% acetic acid (CBP2), and 2% sodium hydroxide (NaOH) solutions (CBP3). Proximate analysis revealed ash as the major component of all samples. The presence of phenols, flavonoids, alkaloids, and glycosides were detected but tannins appeared to be absent in cuttlebones. Mineral analysis indicated that CBP was rich in calcium, which means the material may be considered as a potential calcium source for food products or calcium supplements. The bulk density of CBP2 was significantly lower (p < .05) than those of CBP1 and CBP3, and the water holding capacity (WHC) of CBP1 was significantly higher (p < .05) than those of CBP2 and CBP3. The high bulk density, water and oil holding capacities of CBP demonstrated its potential use as a functional food ingredient.

关键词： electrical conductivity   quality criteria   energy consumption   voltage gradient   SEM images   sensory test  

摘要： BACKGROUND In this study, the alternative method of ohmic heating (OH) was applied to investigate its potential usage in the cooking process for pasta and its comparison with the conventional method. For this purpose, OH was operated at four different voltage gradients (10, 20, 30, 40 V cm(-1)). The electrical conductivity of pasta sigma (S m(-1)) was calculated for the temperature range 22-95 degrees C and a three-phase linear relation between sigma and temperature was determined. RESULTS According to the results, the energy consumption of the OH system and cooking time were lower than the conventional method. Energy conservation was about 73.7% at 40 V cm(-1) and increased up to 90.4% (at 10 V cm(-1)) with lower voltage gradients. Total cooking time, cooking loss, water absorption, degree of gelatinization, volume uptake, energy consumption and sensorial properties were investigated. No significant differences between the results of samples cooked with the conventional method and OH at 30-40 V cm(-1) were found in terms of starch gelatinization degree, volume change, water absorption, and sensorial analysis (P > 0.05). CONCLUSION These results revealed that OH did not cause any negative effects on the quality parameters of pasta samples, and positive effects were observed on energy and time saving. (c) 2021 Society of Chemical Industry.

摘要： Corneal crosslinking (CXL) is the current mainstay treatment for progressive keratoconus. In the past 15 years, a variety of other indications have been tested. A systematic review was conducted to examine these alternative indications for CXL. In total, 143 papers on crosslinking as a treatment for infectious keratitis, bullous keratopathy, pellucid marginal degeneration, and post-laser in situ keratomileusis (LASIK) ectasia and as a way to improve vision either on its own or in combination with other interventions were included. Post-LASIK ectasia is a definite indication for crosslinking. Surprisingly, only limited research has been performed on pellucid marginal degeneration, with no randomized trials available to date. Other interesting applications are the combined use of refractive lasers and crosslinking for suspicious or ectatic corneas and crosslinking as a standalone intervention for minor refractive errors. CXL might offer a solution for refractory bacterial keratitis. In bullous keratopathy, it seems to offer only a transient benefit. Copyright (C) 2021 Published by Wolters Kluwer on behalf of ASCRS and ESCRS

关键词： Quadratic programming   Branch-and-cut algorithm   Alternative direction method   Semidefinite relaxation   Computational complexity  

摘要： We consider a non-convex quadratic program (QP) with linear and convex quadratic constraints that arises from a broad range of applications and is known to be NP-hard. In this paper, we first prove that the alternative direction method converges to a local solution of the underlying QP problem. We then propose a new branch-and-cut algorithm that finds a globally optimal solution to the underlying QP problem within a pre-specified epsilon-tolerance by integrating the alternative direction method with semidefinite relaxation and disjunctive cut techniques. We establish the global convergence of the algorithm and estimate its complexity. Preliminary numerical results demonstrate that the proposed algorithm can effectively find a globally optimal solution to medium-scale QP instances in which the number of negative eigenvalues of the Hessian matrix in the objective function is less than or equals 20.

关键词： Prunus persica   Chilling injury   Antioxidant defense   Respiration pathway   Alternative oxidase  

摘要： Nitric oxide (NO) is an important regulator of plant response to cold stress. In this study, NO treatment delayed the development of chilling injury (CI), inhibited the increase in H2O2 content, O-2(-) production rate and decrease in firmness of postharvest peach fruit. Meanwhile, through RNA-seq analysis, NO treatment up-regulated gene expression of PpG-6-PDH, Pp6-PGDH and PpAOX while it down-regulated the expression of PpGPI and PpHK, suggesting that the pentose phosphate respiratory pathway and cyanide-resistant respiratory pathway were promoted and the glycolysis pathway was inhibited. Furthermore, the PpAOX expression was consistent with the trend of PpPOD1/2 expression and H2O2 content, indicating that AOX may play a role in reducing oxidative damage of peach fruit by scavenging H2O2. Thus, it was concluded that NO treatment could induce the cyanideresistant respiration pathway to enhance antioxidant ability and chilling tolerance in post-harvest peach fruit.

关键词： Adsorption   Rare earth   Recovery   Dysprosium   Vermiculite  

摘要： Background: Dysprosium (Dy) is a critical resource for developing high-tech green energies, and its growing demand implying the need to recover it from secondary sources. Due to the known stability, availability, and high cation exchange capacity, adsorption on vermiculite can be promisor for this purpose. Methods: This work evaluated the dysprosium adsorption and desorption on expanded vermiculite through experiments of equilibrium, thermodynamic, and reuse cycles. Also, the regenerated material was characterized regarding morphological, compositional, thermal, superficial aspects. Significant findings: The equilibrium data achieved high adsorption capacities (0.9 mmol/g), and the sigmoidal isotherms indicated a first layer saturation and progressive surface precipitation, which may favor a Dy selective sorption. The process is feasible and spontaneous, endothermic, and classified as physisorption, advantageous for facilitating dysprosium desorption. From the reusability experiments, high efficiencies of adsorption (99%) and desorption (94%) were reached during five cycles, indicating the effective regeneration of the adsorbent and recovery of the adsorbate using a source of magnesium as eluent (magnesium nitrate hexahydrate solution). The characterization analyzes corroborated the stability and the renewability of the adsorbent. Thus, the material shows a high adsorption capacity and an easy regeneration compared to other complex adsorbents, giving the vermiculite an expressive potential for future applications in rare earth metals recovery. (c) 2021 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

关键词： Blending   Cocoa butter alternatives   Modification   Cocoa butter equivalent  

摘要： Background: Global demand for cocoa butter (CB) product is rising, but the production of CB does not meet the demand, and the availability of this fat is also limited. CB has specific melting properties, and the blooming effect causes defect in its physical properties. The blending of fat is one of the modification methods that offer new functional CB alternatives (CBAs) that can enhance the properties of CB and be applied as substitutes in the food industry. Scope and approach: This review describes the current trends in blending the pure or modified vegetable fats and oils for CBAs production and summarises the characteristics of the blended substances. Typical and recent fats and oils used for CBAs production, including mango seed fat, bambangan kernel fat, shea butter, kokum butter, sunflower stearin and palm oil fractions such as palm oil mid fraction and palm stearin are highlighted. The potential application of the blended fat as CBAs and the changes in their physicochemical, thermal and morphological behaviour are discussed. Key findings and conclusions: The blended fats and oils produced from different sources greatly resemble the characteristics of commercial CB with improved thermal and bloom properties. Thus, the blending processes facilitated the application of various vegetable fats and oils as CBAs to improve the physical quality of the final product in the manufacture of chocolates and confectioneries.

关键词： Geoelectrical survey   Dar-Zarrouk approach   Transmissivity   Hydraulic conductivity   Quaternary basalt aquifer   Syria  

摘要： An alternative geoelectrical approach, based on using the technique of vertical electrical sounding (VES), is developed and proposed to estimate the hydraulic conductivity and transmissivity parameters of the quaternary fractured basalt aquifer (B(1)Q(1)) in Deir Al-Adas region, Southern Syria. Nineteen VES points were executed by Schlumberger configuration, where three of them were made near the available boreholes for comparison. Hydraulic conductivity and transmissivity aquifer parameters are obtained by analyzing conjointly the available pumping test results from the existing boreholes and the electrical Dar-Zarrouk (R) parameters from VES data. An empirical equation between the transverse resistance (R), resulting from VES interpretation, and hydraulic conductivity determined from pumping test is established to estimate geophysically hydraulic conductivity of the Quaternary basalt aquifer. A closed agreement is obtained between the computed hydraulic conductivity and the one determined from pumping test. The established calibrated relationship is consequently used to extrapolate and estimate the transmissivity and the hydraulic conductivity parameters in all VES points, where geoelectrical measurements have been carried out. This extrapolation allows characterizing and deriving the spatial maps of hydraulic conductivity, transmissivity and other related hydrogeophysical parameters in the study area. The integrated acquired results give insights, particularly on the groundwater potentiality of the study region, direction of groundwater flux, and plausible lava directions flux. The resulting maps are important in future modeling processes oriented towards better exploiting of the aquifers. The proposed alternative technique is successfully applied in the study area and can be therefore applied for studying similar basaltic environments worldwide.

关键词： Critical care   Duty hours   work hours   Mathematical modelling   Nurses   Patient safety   Standards of care  

摘要： Objectives: Staffing is the single biggest cost component in the critical care budgets. Due to the fluctua-tion in both bed occupancy and the level of care needs, nursing staff requirement can vary considerably from day to day. This makes the traditional 'fixed roster' staffing system inefficient, costly and potentially unsafe. In this study, we used the existing bed occupancy data to test the viability two 'dynamic' work -force management models. Research methodology: Nursing requirement data were prospectively collected over one year at a thirty-two-bed critical care unit. Using mathematical models, we then tested the concept of two alternative workforce management models and compared the level of staffing, as well as the estimated cost per year. The first was an 'on-call' model, which was a two-tier roster with a standard staffing level and an addi-tional on-call component;the second was a 'predictive' model, which estimated the staffing requirement based on the bed occupancy a few days prior. Setting: Single centre study in a busy district general hospital with a 32-bed critical care unit. Main outcome measures: The number of days with safe staffing levels and the cost of the alternative work -force management models. Results: Data were collected over 331 days. The on-call model was estimated to cost 16% less per year (431,320 pound, or 2,630 nurse-shift equivalent) compared to the fixed roster, while fulfilling the adequate staffing standards in 97% of the days. While the predictive model could also be used to improve the work -force efficiency, this was overall less efficient than the on-call model. Conclusion: The modelled data suggests that the implementation of an 'on-call' model in critical care nursing rostering could potentially improve coverage and appear to be cost effective. (c) 2021 Elsevier Ltd. All rights reserved.