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The prediction of a difficult cholecystectomy has traditionally been based on certain pre-operative clinical and imaging factors. Most of the previous literature reported small patient cohorts and have not used an objective measure of operative difficulty. The aim of this study was to develop a pre-operative score to predict difficult cholecystectomy, as defined by a validated intra-operative difficulty grading scale. Two cohorts from prospectively maintained databases of patients who underwent laparoscopic cholecystectomy were analysed: the CholeS Study (8755 patients) and a single surgeon series (4089 patients). Factors potentially predictive of difficulty were correlated to the Nassar intra-operative difficulty scale. A multivariable binary logistic regression analysis was then used to identify factors that were independently associated with difficult laparoscopic cholecystectomy, defined as operative difficulty grades 3 to 5. The resulting model was then converted to a risk score, and validated on both internal and external datasets. Increasing age and ASA classification, male gender, diagnosis of CBD stone or cholecystitis, thick-walled gallbladders, CBD dilation, use of pre-operative ERCP and non-elective operations were found to be significant independent predictors of difficult cases. A risk score based on these factors returned an area under the ROC curve of 0.789 (95% CI 0.773–0.806, p

Structure, optical and electronic properties of predicted stables Perovskites ABX3 are calculated using DFT approach. The modified Becke-Johnson potential is also used to investigate electrical and optical properties. The density of states and electronic band structure calculations reveal that the predicted stable halides Perovskites ABX3 have a direct as well as indirect band gap, with dielectric function, optical reflectivity, absorption coefficient, optical conductivity, extinction coefficient, refractive index are calculated in different ranges of energy. The maximum value of static dielectric function is observed for KNiI3 and RbIrBr3 are 3.5 and 3 respectively. The highest absorption peak among the all is observed at 26eV for SrLiF3, while refractive index of that SrLiF3 gives peak at 24eV then refractive index decreases below the unity as energy increases up to 27.5eV. The maximum peaks of optical conductivity of predicted stables halides Perovskites are observed in visible to ultraviolet range (1.7eV to 30eV). The maximum peaks of optical conductivity are observed for SrLiF3 at 24eV. For the first time, all of the properties evaluated for predicted stable halides ABX3Perovskites are reported, because no theoretical work is reported yet on most of the physical properties., Comment: 33 pages, 8 figures

Direct bandgap bulk materials are very important for the optical applications. It is therefore important to predict new materials with the desired properties. In the present work, density functional theory is applied to study different physical properties of X$_2$MgZ$_4$($X=$ Sc, Y; $Z=$ S, Se) spinel compounds. Generalized gradient approximation is used to analyze the structural and elastic parameters while modified Becke Johnson exchange potential is applied to calculate electric band profiles and optical properties. All the studied compounds are stable in the cubic structure. Also the energy bandgap is of direct nature. Therefore these compounds can find useful applications in the optoelectrics devices. Optical properties of the compounds are studied in terms of dielectric function, refractive index, extinction coefficient, optical conductivity and reflectivity. The transport parameters like electrical conductivity, Seebeck coefficient, and thermal conductivity are also evaluated., Comment: 14 pages, 10 fugures

A comprehensive study of the structural, electronic, and optical properties of lead-free perovskites has been carried out by means of first principles method based on DFT. The calculations are performed for the compound of the type A2BX6 with A=Rb, and Cs; B=Sn, Pd, and Pt; and X=Cl, Br, and I. The calculated structural parameters (lattice constants and bond lengths) agree well with the experiments. The computed band gap reveals a semiconducting profile for all these compounds showing a decreasing trend of the band gap energy by changing the halide ions consecutively from Cl to Br and Br to I. However, for variation in the B-site cation, the band gap increases by changing the cation from Pd to Pt via Sn. The most likely compounds, Rb2PdBr6 and Cs2PtI6, exhibit a band gap within the optimal range of 0.9-1.6 eV for single-junction photovoltaic applications. The optical properties in terms of the optimal value of the dielectric constant, optical conductivity, and absorption coefficient are also investigated upto the photon energy of 10 eV. Our results indicate that upon changing the halogen ions (Cl by Br and Br by I) the optical properties altered significantly. Maximum dielectric constants and high optical absorption are found for Rb2PdI6 and Cs2PtI6. The unique optoelectronic properties such as ideal band gap, high dielectric constants, and optimum absorption of A2BX6 perovskites could be efficiently utilized in designing high performance single and multi-junction perovskite solar cells., Comment: 25 pages, 12 Figures, 4 Tables

Direct bandgap bulk materials are very important for the optical applications. It is therefore important to predict new materials with the desired properties. In the present work, density functional theory is applied to study different physical properties of X2ZnZ4(X= Sc, Y; Z= S, Se) spinel compounds. Generalized gradient approximation is used to analyze the structural and elastic parameters while modified Becke Johnson exchange potential is applied to calculate electric band profiles and optical properties. All the studied compounds are stable in the cubic structure. Also the energy bandgap is of direct nature. Therefore, these compounds can find useful applications in the optoelectrics devices., 12 pages, seven figures. arXiv admin note: text overlap with arXiv:2008.05126

Direct energy bandgap materials are crucial for the efficient optoelectronics devices. Therefore, the investigation of new direct gap materials is important. In the present work, two novel d-metal sulfides Sc2CdS4 and Y2CdS4 compounds are investigated by using the all electron full potential linearized augment plane wave method. Both the compounds show semiconducting nature and direct band gap with a value 1.886eV for Sc2CdS4 and 2.209eV for Y2CdS4, respectively. Strong hybridization between S-p and Sc/Y-d orbitals present among valence and conduction bands which is beneicial to electrical transport. Key optical parameters are calculated. The static value of the reflectivity R(0) and refractive index n(0) are vary inversely with the energy band gap (Eg). Both the compounds Sc2CdS4 and Y2CdS4 are P-type thermoelectric materials because the Hole carriers dominate the electronic transport. High optical and thermal response for all compounds reveals that they are potential candidates for optical and thermoelectric devices., Comment: 14 pages, 1 Tables, 4 figures

In the current millennium, consumers are becoming more conscious about their dietary patterns with special concern to nutrient retention during cooking methods. There is a need to assess the most convenient and nutritionally better thermal cooking method which causes the least nutrient abuse. The current study investigated the consequence of three cookery methods viz. conventional boiling, steaming and microwave cooking on the physical parameters, β-carotene, vitamin C, total phenolic contents (TPC), total flavonoid contents (TFC) and antioxidant activity (DPPH%) of the particular vegetables. Results revealed that both cooking methods and length of time exerted positive and negative influence on nutritional composition of vegetables. L*, a* and b* values decreased in all samples. In texture analysis, highest force N (Newton) determined in control and microwave cooked samples followed by steaming and boiled samples. Cooking of vegetable by microwaving had the maximum retention for vitamin C, TPC and DPPH% after control. While, s-carotene contents increased in microwave cooking than control. Total flavonoid contents were tending to a decreasing trend in all cooking methods but highest contents were retained in boiling cooking. Amongst the three cookery methods adopted, microwave cooking method emerged as the most appropriate method in terms of retention of nutrients in vegetables.

In this research work, effect of Au ions irradiated Zn1-xNixO (with x = 0.0, 0.02, 0.04 and 0.06) thin films grown by pulsed laser deposition on Si substrate has been investigated. The influence of ions implantation on structural, optical, electronic and morphological properties of the thin films have been examined by X-ray diffraction (XRD), X-ray absorption near edge spectroscopy (XANES), Field emission scanning electron microscopy (FESEM) and ultraviolet-visible (UV-Vis) spectroscopy. XRD results confirm the existence of single phase hexagonal wurtzite structure of ZnO in all the thin films. The preferred orientation were observed along (002) plane. It has also been analyzed that due to co-doping of Au ions and Ni ions, the peaks shifts towards the shorter angle, as a result, lattice expansion has been identified. UV-Vis measurements reveal that the band gap decreases up to x = 0.02 and 0.04 Ni concentration, after that it starts increasing at x= 0.06. XANES analysis reveals the presence of Zn, Ni and O at different edges, K and L edges. FESEM results reveal that the surface morphologies are scarcely changed.&nbsp

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Atmospheric particles (total suspended particles, TSPs) mass samples (288) were collected by high volume samplers at nine sampling locations in Faisalabad, Pakistan from May 2012 to April 2013. These TSP mass samples were subjected to gravimetric and quantitative chemical analyses for determining trace elements (Pb, Cd, Ni, Zn, Cu, Fe) using atomic absorption spectroscopy and water-soluble cations (Ca2+, Mg2+, Na+and K+, NH4+) and anions (Cl−, SO42−, and NO3−) by ion chromatography. The average TSP mass and elemental concentrations at all locations were found to be highest during the dry and lowest during the wet season. The crustal elements Ca, Fe, Mg, and Na were the largest contributors to TSP mass while elements of anthropogenic origin Pb, Cd, Ni, Cu, and Zn had relatively lower concentrations and also showing a high spatial variation. The concentration of TSP and elements exhibited the maxima at the sampling locations characterized by intensive industrial and vehicular activities. The wind rose analysis and the UNMIX model applied to chemical speciation data both identified the same three primary sources of TSP: power plant/refinery, brick kilns, and roadways. The normalized dot product was successfully used to quantify the similarity between different source profiles extracted from UNMIX model. The coupling of UNMIX with wind direction analysis complemented each other and provided a complete assessment of source contributions and locations.

The present study was conducted to investigate whether salt tolerance may be induced in wheat at germination stage by halopriming with different inorganic salts (CaCl 2 , NaCl and CaSO 4 ), and how far these salts affect the mobilization of different nutrients to different parts of seedlings. Seeds of two wheat cultivars (Inqlab-91 and SARC-1) were primed in 50 mmol solutions of CaCl 2 , NaCl or CaSO 4 for 12 h separately and germinated under non-saline and saline (125 mmol NaCl) conditions. All seed treatments hastened germination under saline and non-saline conditions as compared to those of non-primed seeds. However, priming with CaSO 4 enhanced germination of both cultivars under saline conditions more than any other treatment. Maximum root length and fresh and dry weights were obtained in plants raised from seeds primed with CaSO 4 followed by CaCl 2 . Concentrations of Na + and K + in seedlings obtained after priming changed significantly. However, Na + was highest in seedlings raised from seeds primed with NaCl whereas the concentration of K + was highest in the seedlings primed with CaSO 4 . Maximum total sugars and reducing sugars were observed when seeds were treated with CaCl 2 followed by CaSO 4 . In addition, SARC-1 overcame Inqlab-91 in all growth parameters of the seedlings. In conclusion, different salts used for priming in wheat seeds improved the salt stress tolerance; however, CaSO 4 and CaCl 2 proved to be the most effective priming agents in inducing salt tolerance in both wheat cultivars whereas NaCl was a less effective priming agent.

© 2015, Universidad Nacional Autonoma de Mexico. All tights reserved. Spatial and temporal variations in aerosol particulate matter (PM) were investigated for distribution over the four seasons of chemical constituents and particle size fractions in Faisalabad, Pakistan from June 2012 to April 2013. At nine sampling sites, four PM mass size fractions (total suspended particulates [TSP], PM10, PM4and PM2.5) were monitored; simultaneously, TSP mass samples were collected on glass fber flters using a high volume air sampler. TSP samples (144) were subjected to quantitative chemical analyses for determining trace elements (Pb, Cd, Ni, Zn, Cu, Fe) using atomic absorption spectroscopy, and water-soluble cations (Ca2+, Mg2+, Na+, K+, NH4+) and anions (Cl–, SO42–and NO3–) by ion chromatography. The highest PM mass concentrations were observed at industrial sites, while they were somewhat lower in major road intersections and lowest in the remote background site. It was also observed that PM mass concentrations were about two to 20 times higher than the standard limits of the World Health Organization and the US Environmental Protection Agency. Coarse particles (TSP, PM10and PM4) were found to be highest during the summer, while relatively fne particles (PM2.5) were higher during the winter period. Concentrations of all size fractions were lowest during the monsoon sampling period at all sites. Concentrations of different elements and water-soluble ions also followed the similar temporal pattern as PM mass concentrations. The crustal elements Ca, Fe, Mg and Na were the largest contributors to TSP mass while elements of anthropogenic origin (Pb, Cd, Ni, Cu and Zn) had relatively lower concentrations and also showed a high spatial variation. Among the anions, sulfate (SO42–) was the predominant species contributing to 50-60% of the total anion concentration. It was found that rainfall, wind speed and relative humidity were the most important meteorological factors affecting PM concentrations. The evaluation of data presented in this paper will serve as a basis for future regional modeling and source apportionment.

The aim of this study was to develop a single combined once-daily sustained release microencapsulated dosage form of Allopurinol and Nimesulide using Ethyl cellulose as release controlling factor and to evaluate drug release parameters as per various release kinetic models. In order to achieve required sustained release profile, microparticles were prepared using coacervation thermal change technique. The formulated microparticles were also characterized by physical and chemical parameters and results were found in acceptable limits. Different dissolution models were applied to drug release data in order to evaluate release mechanisms and kinetics. The drug release data fit well to the Higuchi expression. Drug release mechanism was found as a complex anomalous one.

In this paper, an angularly stable super wideband metasurface is reported. The designed metasurface consists of a square Split Ring Resonator (SRR) and a circular SRR each having two cuts in adjacent sides for polarization conversion purposes. The proposed metasurface is operating within 11 - 35GHz and having a relative impedance bandwidth of 104.3%. The design shows a stable response for oblique incidence up to 40 degrees. The Polarization Conversion Ratio (PCR) of the proposed metasurface is above 62% within the entire operating band.