Donor Concentration Research Articles

Effect of Adding Cu2O as a Back Surface Field Layer on the Performance of Copper Manganese Tin Sulfide Solar Cells

One of the major limitations causing deadlock in solar cells with higher sulfur content in the photovoltaic absorber material is the unintended formation of an uncontrollable MoS2 layer between the absorber material and Mo back contact, which can affect negatively the efficiency of solar cells. Researchers reported that it is very difficult to control the MoS2 properties such as the conductivity type, thickness, band gap, and carrier concentration in experiments. Considering these challenges, an initial step involved a thorough examination utilizing the one-dimensional solar cell capacitance simulator (SCAPS-1D) to assess the impact of n-MoS2 interlayer thickness and donor concentration on the performance of CMTS solar cells. Our investigation revealed the formation of a “cliff-like CBO” at the CMTS/n-MoS2 interface, facilitating the transport of electrons from the p-CMTS absorber to the Mo back contact, resulting in a significantly higher recombination rate. Subsequently, herein a novel approach is proposed, using Cu2O as a back surface field (BSF) layer due to its low cost, intrinsic p-type properties, and non-toxic nature. Simulation results of a novel heterostructure (Mo/Cu2O/CMTS/CdS/i-ZnO/AZO/Al) of the CMTS-based solar cell are discussed in terms of recombination rate and conduction band alignment at the absorber/BSF interface. A desired “spike-like CBO” is formed between CMTS/Cu2O, which hinders the transport of electrons to the back contact. By optimizing the physical parameters such as thickness and the doping density of the Cu2O layer, an efficiency η of 21.78% is achieved, with an open circuit voltage (Voc) of 1.26 V, short-circuit current density (Jsc) of 24.45 mA/cm², and fill factor (FF) of 70.85%. Our simulation results offer a promising research direction to further develop highly efficient and low-cost CMTS solar cells.

Effects of In Vitro Combination of Nitric Oxide Donors and Hypochlorite on Acanthamoeba castellanii Viability.

To investigate the combined anti-Acanthamoeba effects of nitric oxide (NO) donors and hypochlorite to maximize amoebicidal outcomes while minimizing damage to human corneal epithelial cells (HCECs). Acanthamoeba castellanii and primary cultured HCECs and keratocytes were treated with sodium hypochlorite (NaOCl), NO donors (sodium nitroprusside [SNP] and sodium nitrite [NaNO2]), or a combination of hypochlorite and NO donors. The viability of A. castellanii, HCECs, and keratocytes was assessed. Minimal inhibitory concentration (MIC) and fractional inhibitory concentration of NaOCl and NO donors were determined. The activation of mammalian targets of rapamycin (mTOR) and ERK and the expression of nitrite reductase and Nrf2 were assessed in HCECs using Western blot analysis. The cysticidal effects of combined NaOCl and NO donors were also evaluated. A dose-dependent toxicity was observed in A. castellanii, HCECs, and keratocytes when treated with NaOCl and SNP. The range of tested NaNO2 concentrations showed no significant toxicity to HCECs; however, dose-dependent toxicity to A. castellanii was observed. The MIC of NaOCl against HCECs and A. castellanii was 8.0mg/mL. The MIC of NaNO2 and SNP was 500mM and 10mM in both HCECs and A. castellanii, respectively. Weak attenuation of the mTOR and ERK phosphorylation was observed and Nrf2 expression decreased slightly after exposure of HCECs to 2.0mg/mL NaOCl. For the combination treatment, NaOCl (0.125mg/mL) was selected based on the safety of HCECs and the toxicity of A. castellanii. A more potent anti-Acanthamoeba effect and HCEC toxicity were observed when NaOCl was combined with SNP rather than NaNO2. Combined NaOCl and NO donors had a stronger anti-Acanthamoeba effect compared to either drug alone. This study demonstrates that the combined use of various drugs for the treatment of Acanthamoeba infection can enhance the anti-Acanthamoeba effect while minimizing the toxicity of the individual drug.

Optimization and Performance Analysis of a TiO2/i-CH3NH3SnBr3/CsPbI3/Al(BSF) Heterojunction Perovskite Solar Cell for Enhanced Efficiency.

This paper reports the simulation and optimization of heterojunction perovskite solar cells (PSCs) with a proposed structure of TiO2/i-CH3NH3SnBr3/CsPbI3/Al(BSF) using SCAPS-1D software. The purpose of this study is to investigate the performance of the PSC with CsPbI3 perovskite active layers and i-CH3NH3SnBr3 as the permeable layer. Therefore, the thicknesses of the layers of the heterojunction perovskite are modified in order to find a better conversion efficiency of the solar cell, where the latter's performance is improved by optimizing the absorber's thickness, which is found to be 1 μm, with a permeable layer of 15 μm. The device efficiency of the i-CH3NH3SnBr3/CsPbI3 heterojunction is improved to 38.98%, and optimized parameters are Voc = 1.21 mV, Jsc = 35.63 mA/cm2, and FF = 89.84%. The acceptor concentration (Na), donor concentration (Nd), defect density, and series and shunt resistances are also investigated.

Enhancing photoelectrochemical performance through surface engineering of CdSe and Al-doped CdSe nanoparticles on ZnO/FTO photoanodes

This study presents a comprehensive investigation into the enhanced performance of photoelectrochemical (PEC) cells through the decoration of CdSe and Al-doped CdSe nanoparticles on ZnO rods. The capacitance-voltage study reveals that Al doping increases the donor concentration and improves minority carrier diffusion time while reducing dispersion at grain boundaries. Spectral response analysis demonstrates that CdSe/ZnO/FTO and Al: CdSe/ZnO/FTO photoanodes exhibit maximum short-circuit currents at a wavelength of 675 nm, corresponding to a bandgap of 1.84 eV. Al doping shifts the spectral response to longer wavelengths, indicating an estimated bandgap of 1.72 eV. Furthermore, the effect of surface free energy and polarity on the developed photoanode materials is investigated. CdSe and Al-doped CdSe nano particles on ZnO/FTO surfaces exhibit reduced water contact angles, indicating improved wettability. The surface free energy decreases with Al doping, potentially influencing electrolyte absorption and the interaction between photoanodes and electrolytes. The presence of polar hydroxyl (-OH) groups and Al+++ ions on the Al: CdSe nano particles contributes to their impact on surface free energy. These findings provide valuable insights for optimizing PEC cell performance by manipulating doping concentrations and surface characteristics.

Measuring capillary blood glucose concentration: Is the first blood drop really the right blood drop?

BackgroundCapillary blood glucose (CBG) is fundamental for diabetes mellitus management. However, it is still unclear whether the first or the subsequent blood drops most accurately reflect patients’ blood glucose levels. Methods128 healthy volunteers were included in this prospective cohort study from November 2021 to December 2021. Capillary blood glucose concentrations of the first four blood drops, measured using glucose meters were compared with venous blood concentrations of the respective donors, measured using an in-lab hexokinase method. ANOVA, the Spearman correlation coefficient and Bland-Altman plots were used to analyze the data. ResultsThe mean plasma glucose concentration was 90.46 mg/dl with an SD of ± 14.416 (5.02 ± 0.8 mmol/l). There were statistically strong correlations among the glucose concentrations of all capillary blood drops (correlation coefficients of r > 0.8). The first capillary blood drops showed the lowest mean difference to plasma blood glucose concentrations (+4.92 mg/dl; +0.27 mmol/l), followed by the third drop (+7.28 mg/dl; +0.4 mmol/l), second drop (+7.30 mg/dl; +0.4 mmol/l) and fourth drop (+8.87 mg/dl; +0.49 mmol/l). ConclusionThere is a strong correlation and good agreement between the different capillary blood drops, making all blood drops equally suitable for blood glucose monitoring. In practice, the given setting (clinical or patient self-monitoring) should be considered upon choosing a specific blood drop.

Modeling of highly efficient CNGS based kesterite solar cell: A DFT study along with SCAPS-1D analysis

The electronic and optical properties of Cu2NiGeS4 (CNGS) are examined using the first-principle DFT calculations. A unique mBJ + U potential method is used for the band gap energy calculation of CNGS. With a remarkably high absorption coefficient (104 cm−1), CNGS has become a promising candidate for photovoltaic applications. SCAPS-1D tool is used to simulate a thin-film solar cell with a Mo/MoS2/Cu2NiGeS4 (CNGS)/CdS/ZnO/ZnO:Al structure. The impact of various factors, such as layer thickness, donor and acceptor concentrations, and defect density on the CNGS layer was explored. This study also explores the combination of suitable buffer layers (such as CdS, ZnS, and their alloy Cd1−xZnxS), along with different doping concentrations and thicknesses, to be used as suitable buffer layers in the CNGS solar cell. The simulation outcomes suggest that the optimal thickness for the absorption layer in CNGS solar cells is between 2000 and 2400 nm, while the ideal thickness for MoS2 is 100 nm. The buffer layer should be between 20 and 50 nm. Keeping the defect density of CNGS below 1014 cm−3 is crucial for high efficiency. The optimized results yield an efficiency conversion rate of 20.05%, a 66.77% fill factor, a short-circuit current of 29.67 mA/cm2 and an open-circuit voltage of 0.983 V.

The effect of the antioxidant system resveratrol - iron sulfonitrosyl complex sodium-μ2-dithiosulphate-tetrarntrosyl diferrate tetrahydrate on the mitochondria of pea germ epicotyls in vitro

The interaction of antioxidants - plant polyphenol resveratrol and nitric oxide donor, iron-sulfo-nitrosyl complex with thiosulfate Na2[Fe2(S2O3)2(N0)4]24H2O (TNIC-thio), and their combined action on mitochondria of pea germ epicotyls was studied in vitro. The antioxidant activity of resveratrol (10-6 M), partially compensated the toxic effect of TNIC-thio at high concentration, that is most likely associated with the exhibition of the prooxidant properties of high concentrations of the nitric oxide donor. The effect of resveratrol at concentrations 10-6 M and 10-8 M on the membranes of mitochondria isolated from the pea germ epicotyls treated with 10-8 M TNIC-thio led to coordinations failure in the system of regulation of lipid peroxidation of membranes, that caused antioxidant stress. The action of resveratrol at the dose of 240-5 M had a dual character and practically did not effect on the structural state of mitochondrial membranes.

Properties of κ‐Ga2O3 Prepared by Epitaxial Lateral Overgrowth

AbstractThe structural and electrical properties of undoped and Sn doped κ‐Ga2O3 layers grown by epitaxial lateral overgrowth on TiO2/sapphire substrates using stripe and point masks show that the crystalline structure of the films can be greatly improved relative to conventional planar growth. The undoped films are semi‐insulating, with the Fermi level pinned near EC‐0.7 eV, and deep electron traps at EC‐0.5 eV and EC‐0.3 eV are detectable in thermally stimulated current and photoinduced current transient spectra measurements. Low concentration Sn doping results in net donor concentrations of ≈ 1013 cm−3, and deep trap spectra determined by electron traps at EC‐0.5 eV, and deep acceptors with an optical ionization threshold near 2 and 3.1 eV. Treatment of the samples in hydrogen plasma at 330 °C increases the donor density near the surface to ≈ 1019 cm−3. Such samples show strong persistent photocapacitance and photoconductivity, indicating the possible DX‐like character of the centers involved. For thin (5 µm) κ‐Ga2O3 films grown on GaN/sapphire templates, p‐type‐like behavior is unexpectedly observed in electrical properties and we discuss the possible formation of a 2D hole gas at the κ‐Ga2O3/GaN interface.

Conduction mechanism of Schottky contacts fabricated on etch pits originating from single threading dislocation in a highly Si-doped HVPE GaN substrate

This paper reports the relationship between a single dislocation structure and current leakage mechanism observed in a Pt/n+-GaN Schottky contacts with the combined use of transmission electron microscopy (TEM) and conductive atomic force microscopy (C-AFM). The contacts were fabricated on a substrate grown by hydride vapor phase epitaxy. TEM analysis clarified that large- and small-size etch pits are attributed to mixed/screw and edge dislocations, respectively. Schottky contacts formed on the surfaces of large and small etch pits (L-EPC, S-EPC), a dislocation-free flat area (FLAT), and a Schottky barrier diode with a diameter of 50 μm (SBD) were prepared and their temperature-dependent current-voltage characteristics were measured using C-AFM. Analysis of the forward bias characteristics revealed that the Schottky barrier height increased and the ideality factor approached unity with increasing temperature. Such temperature dependence of the barrier height was well explained by barrier inhomogeneity at the metal/semiconductor interface. From the analysis of the reverse bias characteristics, we found that field emission (FE) currents caused by the high donor concentration of the sample were the dominant conduction mechanism for S-EPC and FLAT. On the other hand, for L-EPC, the FE currents were overlapped by Poole-Frenkel emission (PFE) currents. For SBD, the leakage currents were successfully explained by the FE and thermionic field emission (TFE) mechanisms by assuming dislocation regions with a lowered barrier height. These findings suggest that mixed dislocations are associated with PFE and lower the Schottky barrier.

Cross-scale models for iron oxides bioreduction rates

Bioreduction rates of iron (Fe) oxides are a key variable for predicting the fate and transport of Fe and contaminants in subsurface environments. Such rates, however, vary significantly at different spatial scales, and change in orders of magnitude even within the same scale. This study first collected and consistently processed the data of Fe oxide bioreduction rates from literature, which were then used to train a machine learning (ML) model that resulted in a well-fitted relationship between the cross-scale bioreduction rates and common influencing factors including electron donor concentrations, electron numbers, Fe concentrations, cell numbers, and reaction Gibbs free energy. Sensitivity analysis was performed to provide insights into the relative role of the influencing factors and how they affect the rates. The result indicated that their effects were generally consistent with saturation type models. New experiments of iron oxide bioreduction were performed to validate the ML-based cross-scale model. The result showed that ML-based model well predicted the experimental results, indicating the effectiveness of the model. The result has a strong implication for developing the models of cross-scale reaction rates of iron oxide bioreduction in environmental systems and for predicting the fate and transport of iron and contaminants.

Influence of buffer layer on copper doped tin sulfide solar cell: A Numerical approach

The proposed paper has examined the copper tin sulfide (CTS) semiconductor which is a ternary compound with extremely high absorption coefficient (105 cm−1) and ideal bandgap ranging from 0.9 to 1.6 eV. Non-toxic and widely available elements present on the earth constitute the elements of CTS. In this work, we have numerically simulated the structure: ITO coated polyethylene terephthalate (PET)/ZnO/(CdS, ZnS, CdZnS, TiO2)/CTS/Al using wx-AMPS software.In the structure different layers are: ITO coated PET which is a flexible substrate and acting as a front layer. It has been optimized by optimizing its layer thickness as 140 nm; ZnO as intrinsic layer; CdS/ZnS/CdZnS/TiO2 as buffer layers; CTS as absorber layer and Al as back contact. Different buffer layer variation was studied by varying its thickness and donor concentration. The QE curve shown in the result shows that at lower wavelength also, the QE value for CdZnS and TiO2 is high. Therefore, for furthermore investigation, these two buffer layers were considered. After optimizing the buffer layer, absorber layer optimization was carried out by varying its thickness, acceptor concentration and defect density values. By considering CdZnS as buffer layer, the optimized result which we got as, VOC = 0.819 V, JSC = 25.77 mA/cm2, FF = 85.59 %, η = 18.08 % and by considering TiO2 as buffer layer, the optimized result which we got as, VOC = 0.818 V, JSC = 25.55 mA/cm2, FF = 84.41 %, η = 17.66 %.

Interactions of hydrogen atoms with boron and gallium in silicon crystals co-doped with phosphorus and acceptors

Reports showing that hydrogen and group-III acceptors play an important role in Light- and elevated Temperature-induced Degradation (LeTID) of Si-based solar cells highlight the need for a better understanding of interactions between these two species. In this contribution, a combination of junction spectroscopy techniques and first principles modelling has been used to study hydrogen-induced changes in electrical properties of either boron or gallium Czochralski-grown silicon co-doped with phosphorus in order to produce n-type material facilitating novel techniques to assess recombination active defects. The interactions of hydrogen with acceptor atoms have been induced via annealing of these co-doped hydrogenated samples with the application of reverse bias (RBA). These treatments have resulted in a significant increase in the net shallow donor concentration in depletion regions of both materials and in the appearance of a strong electron emission signal due to a trap with an energy level at about Ec −0.18 eV in the DLTS spectra of Si:P + B material. It is argued that this trap is related to the donor level of a BH2 complex. Calculations using density functional theory have shown that the BH2 defect has a charge-state dependent geometry, which turns out to be crucial for the proposed non-radiative recombination mechanism. The BH2 defect is therefore suggested to be the root cause of LeTID in boron-doped Si. In contrast, modelling results predict that GaH2 is a defect with shallow energy levels, without the characteristic features of a recombination centre. This is corroborated by the results of electrical measurements on hydrogenated Si:P + Ga subjected to RBA. Conventional annealing treatments were subsequently used to assess the thermal stability of acceptor-H related defects. Based on the obtained results, the peculiarities of hydrogen interactions with boron and gallium acceptors are discussed.

A promising artificial intelligence-based tool to simulate the efficient and sustainable hydrogen sulfide elimination using deep eutectic solvents

This work applies artificial intelligence (AI) methodologies and relevance tests to investigate the hydrogen sulfide (H2S) elimination capacity of a wide range of DESs (deep eutectic solvents). A great deal of effort is made to deploy a practical model to predict the H2S removal ability of eighteen different DESs as a function of DES chemistry, equilibrium conditions, and H2S-DES interaction. Multiple linear regression and Pearson’s correlation methods are employed to measure the direction and relative influence of hydrogen bond acceptor (HBA), hydrogen-bond donor (HBD), the HBA and HBD concentration, water dose, pressure, temperature, and absorption enthalpy on the DES capacity to absorb H2S molecules. Both tests approve that absorption enthalpy (ΔH) of H2S by DESs, hydrogen bond acceptor (HBA), pressure, and temperature mainly control the considered separation process. The relevance tests also identify that the H2S solubility in DESs improves by either a decrease in ΔH, HBA molecular weight, and temperature or an increase in pressure. Then, five diverse AI types are applied to estimate H2S molality in DESs as a function of the involved explanatory variables, and their accuracy is compared. The sensitivity analysis clarifies that the cascade neural network (CNN) with only 20 hidden nodes is the most reliable AI tool to simulate the considered problem. Further investigations approve that the CNN tool provides more accurate predictions for H2S solubility in DESs when it is equipped with the logarithm and tangent sigmoid transfer functions in the hidden and output neuronic layers. Also, amongst eleven checked training algorithms, the Levenberg-Marquardt presented the best performance. This structure-regulated CNN tool can predict 512 actual H2S solubility records in DESs with the MSE = 0.0031, MAE = 0.02, RAE = 2.03%, AARE = 3.03%, and multiple-R = 0.99943.

O-016 Sperm motility has declined between 2017 and 2022 among candidate sperm donors in Denmark

Abstract Study question Has sperm quality among candidate sperm donors in Denmark changed in recent years (2017-2022)? Summary answer Although sperm concentration of candidate donors did not change, sperm quality (motility) declined by ∼35% after controlling for age and other potential confounds. What is known already Questions remain about whether human sperm quality has declined in recent decades. Whilst some studies support this trend, others dispute it due to potential biases in the populations studied or the different methodological approaches to measuring sperm quality. Resolution of this issue is important because of the implications for human fertility, as well as for those involved in the recruitment of donors for use in Medically Assisted Reproduction. Study design, size, duration We analyzed the semen quality of 6,774 candidate sperm donors attending for their first semen analysis at Cryos International from 2017 to 2022 at four cities in Denmark: Aarhus, Aalborg, Copenhagen, and Odense. We analyzed only the first sperm sample, whether or not the candidate was eventually accepted as a donor. All donor candidates were between 18 and 46 years old and lived in or near these four cities. Participants/materials, setting, methods Ejaculates were examined within one hour of production. Semen volume (mL) was estimated by weight and both total sperm concentration (106/mL) and the concentration of grade A and B spermatozoa were measured using the same protocols and CASA-system across all years at each site. Analyses were controlled for age, site, ejaculate volume, and the average monthly temperature when the ejaculate was produced. We used longitudinal data from accepted donors to test for methodological biases. Main results and the role of chance From 2017 to 2022, there was no evidence of changes in either semen volume (median = 3.5 mL) or sperm concentration (median = 58 million/mL) in the ejaculates of candidate donors. There was, however, clear evidence of a decline in the concentration (and total number) of grade A and B motile sperm. For the average candidate sperm donor that we studied, the concentration of grade A sperm declined from 5.15 [95% CL: 4.18, 6.34] million/mL in 2018 to 3.33 [2.71, 4.08] million/mL in 2022. This corresponds, for example, to a predicted decline in sperm quality of ∼35% for a 25-year-old candidate from Aarhus in a month when the average daily high temperature was 18.5 °C. The same pattern was evident from all four cities, but candidates at Aarhus had lower overall sperm quality (grade A sperm motility) than candidates at the other three cities. Analysis of the longitudinal data from repeated donations from all 'accepted' donors during this same period (2017 – 2022), allowed us to rule out methodological factors (sperm collection, CASA, statistical anomalies) that might have influenced these findings. Limitations, reasons for caution We cannot rule out the possibility that men with poor sperm quality were more likely to apply to be donors during the global pandemic, or that the lifestyles of candidate donors had changed during this period because of lockdowns or changes in work patterns. Wider implications of the findings Candidate sperm donors are a useful population in which to monitor changes in human semen quality over time. The results may have implications for human fertility and the recruitment of sperm donors, where motile sperm concentration is an essential selection criterion. Trial registration number not applicable

780 nm near-infrared photorefractive holograms recorded in undoped Bi12TiO20 crystal under the action of external electric field

In this paper, we studied recording and erasure of photorefractive holographic gratings recorded at 780 nm in an undoped Bi12TiO20 (BTO) crystal sample under the action of an externally applied electric field. The diffraction efficiency was measured by directly chopping the diffracted beams by the gratings recorded in a two-wave mixing setup without using of any phase-modulation technique of the recording beams or feedback mechanism. An enhancement of 3.5-fold in the diffraction efficiency was observed when the applied electric field increased from 0 to 6 kV/cm. The theoretical dependence of the diffraction efficiency on the external electric field considering the effect of screening of charges near the electrodes was investigated, and the result is supported by good fit to the experimental data, allowing us to compute characteristic parameters of the material, including the values of photoactive donor concentrations (ND1)eff ≈ 0.12 × 1016 cm−3 and (ND2)eff ≈ 0.8 × 1015 cm−3, respectively, for the levels placed at 1.6 eV and 1.3 eV below the conduction band responsible for photorefractive recording in the BTO sample.

Rapid synthesis and characterizations of defect-enhanced WO3-δ thin film electrode for effective energy storage application in asymmetric supercapacitor devices

Oxygen vacancy-doped WO3-δ thin film electrode with improved conductivity and high areal capacitance was synthesized via mild electrochemical oxygen de-intercalation of electrodeposited WO3 thin film. The X-ray diffraction (XRD) analysis revealed the presence of monoclinic phase W18O49 of the doped thin film electrode. Raman spectroscopy analysis confirmed the presence of lower valence W5+ in the WO3-δ film. Electrical characterizations of doped WO3-δ and undoped WO3 films show that the doped electrode exhibits far lower sheet resistance and resistivity than the undoped WO3 sample. Mott-Schottky analysis of the samples shows that the vacancy-doped WO3-x possesses a higher donor concentration than the stoichiometric WO3. Electrochemical characterizations by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD,) and electrochemical impedance spectroscopy (EIS) confirmed the superior pseudocapacitive charge storage metrics via its improved volumetric capacitance of 366.12 F·cm−3 (16.0 mF·cm−2) and reduced equivalent series as well as charge transfer resistance over WO3 thin film. This study demonstrated the synthesis of oxygen vacancy-doped WO3-δ thin film using a homemade two-electrode cell facility instead of the popular energy-consuming vacuum-assisted film deposition under controlled-atmosphere conditions. Besides, the vacancy-doped WO3-δ electrode shows a strong charge storage capability in the far negative operating potential range, indicating its suitability as an anode electrode for fabricating high-energy asymmetric supercapacitors.

Lipase catalyzed chemo-enzymatic synthesis of propranolol: A newer enzymatic approach

The biocatalytic processes are greener and safer alternatives for synthesis of drug and drug intermediates. This study reports one such approach of chemo-enzymatic synthesis of propranolol, a β-adrenergic receptor blocker. A green synthetic route was employed for synthesis of propranolol using enzymatic kinetic resolution. Racemic mixture of secondary alcohol [1-chloro-3-(naphthalen-1-yloxy)propan-2-ol] (RS)-5 was synthesized chemically in two step reaction and further its enzymatic kinetic resolution was carried out by using lipase to synthesize enantiomeric forms (R)-5 and S-(6) of propranolol. The kinetic resolution of (RS)-5 involves the transesterification of secondary racemic alcohol in which vinyl acetate is used as acyl donor. Initially, we screened commercially available lipases for kinetic resolution and of all the screened lipases Addzyme 001 showed the best results. The several reaction parameters such as organic solvent, acyl donor, temperature, reaction time and enzyme concentration were optimized to improve rate of reaction and to achieve maximum enantioselectivity. Addzyme 001 at 40 mg shows the maximum conversion rate of 49% using cyclohexane as the organic solvent, vinyl acetate as the acyl donor and it was found that the reaction yield was higher for (R)-5 along with the (S)-6 (eep = 98%, ees = 97%) at 40 °C in 48 h. Further, the treatment of (R)-5 with isopropyl amine resulted into formation of (S)-propranolol eep = 98%, and overall yield 29% independently. To synthesize (R)-propranolol, S-(6) acetate was produced enzymatically and was further deacylated by chemical hydrolysis for the production of (R)-propranolol. This study reports newer approach for synthesis of (R) and (S) propranolol using chemoenzymatic route.

Efficient site-specific integration in CHO-K1 cells using CRISPR/Cas9-modified donors.

Conventional methods applied to develop recombinant CHO (rCHO) cell line as a predominant host for mammalian protein expression are limited to random integration approaches, which can prolong the process of getting the desired clones for months. CRISPR/Cas9 could be an alternative by mediating site-specific integration into transcriptionally active hotspots, promoting homogenous clones, and shortening the clonal selection process. However, applying this approach for the rCHO cell linedevelopment depends on an acceptable integration rate and robust sites for the sustained expression. In this study, we aimed at improving the rate of GFP reporter integration to the Chromosome 3 (Chr3) pseudo-attP site of the CHO-K1 genome via two strategies; these include the PCR-based donor linearization and increasing local concentration of donor in the vicinity of DSB site by applying the monomeric streptavidin (mSA)-biotin tethering approach. According to the results, compared to the conventional CRISPR-mediated targeting, donor linearization and tethering methods exhibited 1.6- and 2.4-fold improvement in knock-in efficiency; among on-target clones, 84% and 73% were determined to be single copy by the quantitative PCR, respectively. Finally, to evaluate the expression level of the targeted integration, the expression cassette of hrsACE2 as a secretory protein was targeted to the Chr3 pseudo-attP site by applying the established tethering method. The generated cell pool reached 2-fold productivity, as compared to the random integration cell line. Our study suggested reliable strategies for enhancing the CRISPR-mediated integration, introducing Chr3 pseudo-attP site as a potential candidate for the sustained transgene expression, which might be applied to promote the rCHO cell linedevelopment.

United Kingdom aid cuts: implications for financing health systems.

The United Kingdom (UK) used to be the second largest bilateral provider of official development assistance (ODA) for health. However, in 2021 the UK government cut its annual aid budget by 30%. We aim to understand how these cuts might affect financing for health systems in UK aid recipient countries. We conducted a retrospective analysis of domestic and external funding for 134 countries that received UK aid for the 2019-2020 budget year. We grouped countries into two cohorts: those that continued to receive aid in 2020-2021 ("budget") and those that did not ("no budget"). Data was collected from publicly available datasets and we compared UK's ODA, UK's health ODA with total ODA, general government expenditures and domestic general government health expenditure to assess the donor dependency and donor concentration of budget and no budget countries. Budget countries are more reliant on external aid to finance their governments and health systems than no budget countries, with a handful of exceptions. While the UK does not appear to be a major ODA contributor among most no budget countries, it is in many budget countries. Two no budget countries in particular may be faced with health systems financing challenges given their high ratios of UK health aid to domestic government health expenditures: the Gambia (1.24:1) and Eritrea (0.33:1). Although "safe" for this budget cycle, a number of low-income countries in Sub-Saharan Africa have very high ratios of UK health aid to domestic government health expenditures, including South Sudan (3.15:1), Sierra Leone (0.48:1), and the Democratic Republic of Congo (0.34:1). The 2021-2022 UK aid cuts could have negative impacts in a few countries highly dependent on UK health aid. Its departure could leave these countries with rather large funding gaps to fill and create a more concentrated donor climate.

Consequences of grain boundary barriers on electrical characteristics of CIGS solar cells

The following work deals with interpreting defect spectroscopy results for CIGS solar cells. The motivation and brief background for defect physics investigation in photovoltaic materials is presented. Since the subject of defect spectroscopy interpretation in CIGS has been discussed for many years and plenty of experimental results are available, we present here those that we believe are the most important. Characteristic and essential features of signals observed in CIGS are shown, which have eluded unambiguous interpretation and made it impossible to propose a coherent physical mechanism so far. The physical models co-existing in the CIGS community are also briefly discussed. Emphasis is placed on which features of the observed signals are explained by models and which are not. The main aim of the presented work is to introduce a new model describing the results of admittance spectroscopy in CIGS solar cells based on the existence of hole barriers at the grain boundaries. Most completely, the presented model explains the characteristic features of the measured signals, including the variability of the activation energy of the observed processes, its dependence on the hole concentration, and its correlation with the results of conductivity measurements. The model assumptions and simulation results show how the concentration of surface donors at the grain boundaries affects the height of the grain boundary barriers and the measured concentration of holes in the CIGS. The simulations are presented for different grain sizes and confronted with experimental results.