Recombination Rate Research Articles

Addressing accuracy by prescribing precision: Bayesian error estimation of point defect energetics

With density functional theory (DFT), it is possible to calculate the formation energy of charged point defects and in turn to predict a range of experimentally relevant quantities, such as defect concentrations, charge transition levels, or recombination rates. While prior efforts have led to marked improvements in the accuracy of such calculations, comparatively modest effort has been directed at quantifying their uncertainties. However, in the broader DFT research space, the development of Bayesian Error Estimation Functionals (BEEF) has enabled uncertainty quantification (UQ) for other properties. In this paper, we investigate the utility of BEEF as a tool for UQ of defect formation energies. We build a pipeline for propagating BEEF energies through a formation-energy calculation and test it on intrinsic defects in several materials systems spanning a variety of chemistries, bandgaps, and crystal structures, comparing to prior published results where available. We also assess the impact of aligning to a deep-level transition rather than to the VBM (valence band maximum). We observe negligible dependence of the estimated uncertainty upon a supercell size, though the relationship may be obfuscated by the fact that finite-size corrections cannot be computed separately for each member of the BEEF ensemble. Additionally, we find an increase in estimated uncertainty with respect to the absolute charge of a defect and the relaxation around the defect site without deep-level alignment, but this trend is absent when the alignment is applied. While further investigation is warranted, our results suggest that BEEF could be a useful method for UQ in defect calculations.

Tuning the structural and optical parameters of Li1.2Ni0.4Fe2O4 for efficient degradation of dye and pharmaceutical compounds

Sol-gel auto-combustion route was used for the fabrication of lithium and dysprosium co-doped nickel ferrite (LNDFO). The composite of LNDFO with gCN (LNDFO@gCN) was prepared via ultra-sonication method. The synthesized samples were tested by photodegrading organic pollutants. Different characterization techniques were employed to examine the structure, morphology, elemental composition, and bandgap of prepared photocatalysts. The optical bandgap energy of LNFO, LNDFO, and LNDFO@gCN was 2.92 eV, 2.73 eV, and 2.64 eV, respectively. LNDFO@gCN had the lowest recombination rate of charged species and greater surface area, which makes it an efficient photocatalyst. The degradation shown by LNDFO@gCN for panadol, MB, and phenol was 90.04 %, 93 %, and 89.5 % respectively. EIS and Mott-Schottky analysis revealed that the charge transfer resistance of fabricated composite was less than bare and doped samples, and they were n-type semiconductor materials. As compared to all fabricated photocatalysts, LNDFO@gCN was most efficient photocatalyst due to its high degradation ability, easy formation, and higher charge separation rate.

Synergistic effects of Fe2O3 supported on dendritic fibrous SBA-15 for superior photocatalytic degradation of methylene blue

Environmental pollution caused by dye effluent has attracted much attention, and thus developing photocatalysts with superior photodegradation performance is an imperative task. A series of Fe supported on dendritic fibrous SBA-15 (Fe/DFSBA-15) catalysts with various Fe contents were prepared using a microemulsion coupled with ultrasonic-assisted impregnation methods. The findings revealed that the structural stability of DFSBA-15 was unaffected by the amount of Fe loaded. As the Fe loading increased, the size of Fe2O3 nanocrystals increased while the catalysts’ surface area decreased. The bandgap energy of the catalyst decreased with increasing Fe loading and became constant after reaching an optimal Fe loading of 10 wt%. The one-factor-at-a-time study revealed that 10Fe/DFSBA-15 degraded 94.72 % of methylene blue (MB) within 180 min at 1.5 g/L catalyst dosage, pH 8, and 10 mg/L of concentration, owing to Si-O-Fe coordination, modest Fe2O3 crystallite size, homogeneous metal distribution, slower recombination rate, and low bandgap energy. The advantageous features of 10Fe/DFSBA-15 resulted in accelerating the photodegradation rate, where 10Fe/DFSBA-15 is found as the optimal catalyst. The addition of Fe particles to the DFSBA-15 largely improved their photocatalytic activity toward MB degradation, making it a potential candidate for removing pollutants from aqueous solutions.

Linkage equilibrium between rare mutations.

Recombination breaks down genetic linkage by reshuffling existing variants onto new genetic backgrounds. These dynamics are traditionally quantified by examining the correlations between alleles, and how they decay as a function of the recombination rate. However, the magnitudes of these correlations are strongly influenced by other evolutionary forces like natural selection and genetic drift, making it difficult to tease out the effects of recombination. Here we introduce a theoretical framework for analyzing an alternative family of statistics that measure the homoplasy produced by recombination. We derive analytical expressions that predict how these statistics depend on the rates of recombination and recurrent mutation, the strength of negative selection and genetic drift, and the present-day frequencies of the mutant alleles. We find that the degree of homoplasy can strongly depend on this frequency scale, which reflects the underlying timescales over which these mutations occurred. We show how these scaling properties can be used to isolate the effects of recombination, and discuss their implications for the rates of horizontal gene transfer in bacteria.

Synergistic role of Bi-functional NiS2/MoS2 dandelion flowers for electrochemical performance towards clean energy H2 production

MoS2 and NiS2 are promising materials that have been extensively used for efficiently facilitating energy storage and hydrogen production owing to the existence of rich active sites. To cope with the worldwide energy crises, target oriented NiS2/MoS2 dandelion flowers like composites have been developed and their synergistic effect has been studied for their potential utilization energy applications. NiS2/MoS2 dandelion having emerging nanowires (d=20 nm) played synergistic role and exhibited enhanced specific capacitance (711 F/g) as equated to individual MoS2 (481 F/g) and NiS2 (620 F/g). This improvement is credited to the numerous active sites generation, rapid ions transfer and powerful synergistic impact caused by NiS2/MoS2 composite. More than 91 % of capacitance has been observed for NiS2/MoS2 composites after 4000 cycles, demonstrating their exceptional stability owing to the uniform growth. Along with higher specific capacitance, considerably higher H2 production rate (8 µmol h−1g−1) for NiS2/MoS2 composites have also been observed. Correlation between recombination rate and optical characteristics have been well-explained by photoluminescence. Thus bi-functional NiS2/MoS2 composite material has prospective applications in H2 production and energy storage devices.

Photocatalytic Degradation of Sulfamethoxazole by Cd/Er-Doped Bi2MoO6

Bi2MoO6 (BMO) is a typical bismuth-based semiconductor material, and its unique Aurivillius structure provides a broad space for electron delocalization. In this study, a new type of bismuth molybdate Cd/Er-BMO photocatalytic material was prepared by co-doping Er3+ and Cd2+, and the performance of the photocatalytic degradation of sulfamethoxazole (SMZ) was systematically studied. The research results showed that the efficiency of SMZ degradation by Cd/Er-BMO was significantly improved after doping Er3+ and Cd2+ ions, reflecting the synergistic catalytic effect of Cd2+ and Er3+ co-doping. Cd/Er-BMO doped with 6% Cd had the highest degradation efficiency (93.89%) of SMZ under visible light irradiation. The material revealed excellent stability and reusability in repeated degradation experiments. In addition, 6% Cd/Er-BMO had a smaller particle size and a larger specific surface area, which is conducive to improving the generation efficiency of its photogenerated electron-hole pairs and reducing the recombination rate, significantly enhancing the photocatalysis of the material. This study not only provides an effective photocatalyst for degrading environmental pollutants such as SMZ, but also provides an important scientific basis and new ideas for the future development of efficient and stable photocatalytic materials.

A maghemite (γ-Fe2O3) incorporated activated carbon photocatalytic nanocomposite fabricated via Co-precipitation utilized against degradation of methyl orange

The γ−Fe2O3/ACP has been synthesized in different ratios by facile co-precipitation method to degrade the methyl orange dye. In order to check the stability and potential of photo activated catalyst, UV, PL, SEM, XRD, EDX, FTIR and Zeta Potential are discussed here. The bandgap has been reduced from 2.06 eV to 1.86eV. Here, 1:3 γ−Fe2O3/ACP sample showed maximum reduced bandgap of 1.86 eV. The PL spectroscopy showed that 1:3 sample has less intensity, which in turn have 94 % photo degradation of methyl orange dye in 180min. The 1:3 sample showed 87 % degradation of methyl blue dye at 125mins light irradiation and proved as an optimal concentration of ACP in maghemite at pH of 11. The inclusion of carbon into maghemite enhances the overall properties by reducing the charge recombination rate. No impurity has been found in the final synthesized samples confirmed through EDX. The XRD and SEM revealed that size of crystallites and particle size increases, which confirms that bandgap is reduced. While trapping techniques and recycling techniques has been employed on the optimal concentration sample to check its stability towards degradation of methyl orange (MO) dye. The photo catalysis through such nanocomposite is not reported before. The 1:3 sample showed promising potential towards pollutants degradation in waste water treatment.

Enhancing charge extraction in BiVO4 photoanodes by ZrCl4 treatment of SnO2 hole-blocking layers

In the search for more efficient and sustainable photoelectrochemical devices, BiVO4 is nowadays one of the best-performing photoanode material, with favourable band structure for water oxidation. However, BiVO4 photoanodes face challenges such as poor charge transport and slow kinetics. To address these issues, SnO2 films are commonly used as hole blocking layers, reducing recombination rate and enhancing charge lifespan and overall productivity. Yet, this method encounters problems like high defect concentrations at the SnO2/BiVO4 interface and pinholes in the SnO2 layer, which lead to charge recombination. In this study, we explore a ZrCl4 treatment to improve the effectiveness of SnO2 as a hole-blocking layer in BiVO4 photoanodes. Our findings, supported by detailed optoelectronic characterization and continuous and modulated electrochemical analysis, reveal that ZrCl4 treatment significantly enhances the hole-blocking properties of SnO2. This treatment results in a 37 % increase in photocurrent density at 1.23 VRHE and a 40 mV shift in the onset voltage, demonstrating a substantial improvement in overall photoanode efficiency.

Facile construction of ZnWO4/g-C3N4 heterojunction for the improved photocatalytic degradation of MB, RhB and mixed dyes

This study presents the construction of binary ZnWO4/g-C3N4 nanocomposite via a facile hydrothermal approach to enhance the photocatalytic performance under the visible light irradiation. The proposed ZnWO4/g-C3N4 nanocomposite photocatalyst shows excellent photodegradation towards organic dyes, such as methylene blue (MB) and rhodamine B (RhB). The optimal loading of ZnWO4 and g-C3N4 leads to the synergistic effect which plays a predominant role in inhibiting the fast electron-hole pairs recombination rate at the interface of ZnWO4/g-C3N4 photocatalyst. The degradation rates of MB and RhB is achieved around 92.9 % and 88.8 % under the visible light irradiation for 120 min. According to our findings, the radical quenching experiments suggested that the ●OH radicals played a positive impact in the photodegradation process. Since, our proposed photocatalyst exhibit superior photocatalytic activity towards the individual MB and RhB degradation. The ZnWO4/g-C3N4 photocatalyst were further applied to demonstrate the degradation of mixed dyes (MB and RhB) at an irradiation time of 180 min. In the mixed dye solution, the ZnWO4/g-C3N4 photocatalyst achieved a highest reaction rate of 0.010 min−1 for MB and 0.012 min−1 for RhB with the degradation rate of 87.8 % and 83.3 % for RhB and MB, respectively. For the mixed dyes, the radical quenching experiments confirmed that the ●OH radicals are responsible for the fast photodegradation. Additionally, the practicality of the proposed ZnWO4/g-C3N4 photocatalyst towards the degradation of MB, RhB and the mixed dyes were examined in the tap water samples. Furthermore, the plausible photodegradation mechanism of ZnWO4/g-C3N4 photocatalyst was proposed in detail. This study provides a new insight for the simultaneous degradation of mixed chemical pollutants using our proposed ZnWO4/g-C3N4 photocatalyst.

Synthesis, nonlinear optical activity, solvents effect, β-cyclodextrin effect, and cytotoxic activity on skin fibroblast and breast cancer cell lines of a new chalcone derivative of nabumetone

The use of small organic molecules, such as chalcones, for efficient applications as organic luminescent materials has attracted increasing attention owing to their interesting optical, photophysical, and biological properties. In this study, a new chalcone, 1-(4-isopropylphenyl)-5-(6-methoxynaphthalen-2-yl)pent-1-en-3-one (INM), was synthesized via base condensation between nabumetone and cuminaldehyde. INM was subsequently identified and characterized by FT-IR, NMR spectroscopy (1H and 13C), mass spectrometry, elemental analysis, X-ray diffraction, thermogravimetric analysis, and FESEM studies. Investigation of the solvent effect revealed that the π → π* transition involved a bathochromic shift from hexane to water and a large Stokes-shifted, twisted intramolecular charge-transfer emission in water. Diffuse reflectance spectral studies confirmed the formation of transparent INM chalcones with excellent crystallinity, and photoluminescence studies substantiated the low recombination rate of electrons and holes. Tauc plot analysis with the Kubelka–Munk algorithm revealed higher direct (3.57 eV) and indirect (3.41 eV) bandgap energies of INM. Density functional theory calculations at B3LYP/6-31G(d,p) revealed that INM had promising nonlinear optical activity (β ≈ 30.504 × 10−30 compared to a reference material, urea. Cell biocompatibility was evaluated after culturing skin fibroblasts and breast cancer cells with INM using the MTT assay and fluorescence microscopy of the live/dead cell assay. It was observed that INM exhibited good NIH/3T3 cell adhesion and proliferation and the weak inhibiting ability of MDA-MB231.

Role of Nanoparticle Size in the Photocatalytic Degradation of Pollutants

Purpose: The aim of the study was to assess the role of nanoparticle size in the photocatalytic degradation of pollutants. Methodology: This study adopted a desk methodology. A desk study research design is commonly known as secondary data collection. This is basically collecting data from existing resources preferably because of its low cost advantage as compared to a field research. Our current study looked into already published studies and reports as the data was easily accessed through online journals and libraries. Findings: The study indicated that smaller nanoparticles exhibit a higher surface area-to-volume ratio, providing more active sites for pollutant interaction and adsorption, which enhances the overall degradation process. Additionally, smaller nanoparticles tend to have higher charge carrier mobility and reduced recombination rates of electron-hole pairs, further improving photocatalytic activity. This increased efficiency is critical in environmental applications, as it allows for the effective breakdown of various contaminants, including dyes, pesticides, and pharmaceuticals, at lower catalyst loadings and shorter reaction times. The optimization of nanoparticle size, therefore, plays a crucial role in developing advanced photocatalytic systems for environmental remediation. Implications to Theory, Practice and Policy: Optical absorption theory, surface area and reaction kinetics theory and charge carrier dynamics theory may be used to anchor future studies on assessing the role of nanoparticle size in the photocatalytic degradation of pollutants. Develop robust methodologies for synthesizing nanoparticles with precise control over size distribution. Establish standardized protocols for evaluating the performance and safety of nanoparticle-based photocatalytic materials. This includes setting benchmarks for degradation efficiency, durability, and potential environmental impacts.

Photocatalytic degradation of Alizarin Red contaminant using Ag2CrO4@NiFe-LDH composite under visible light irradiation.

In this study, Ag2CrO4@NiFe-LDH nanoparticles were synthesized by hydrothermal method for photocatalytic degradation of Alizarin Red (AR) dye. Three composites with different molar percentages were prepared, among which 50%Ag2CrO4@50%NiFe-LDH composite was the best sample with a removal rate of 97.1% in AR degradation. Also, the properties, structure, and characteristics of pure Ag2CrO4 and NiFe-LDH and their composites were determined by XRD, FESEM, FTIR, EDX mapping, and UV-visible analyses. It was found that Ag2CrO4@NiFe-LDH composites with the formation of heterogeneous structure of Z-scheme, in addition to increasing the active sites and increasing the specific surface, decrease the recombination rate of pure Ag2CrO4 and NiFe-LDH. Also, the Box-Behnken design technique, which is one of the most common designs used in response surface methodology, was used to optimize the operating conditions and investigate the effect of 4 independent parameters: catalyst amount, solution concentration, pH, and light intensity. The importance of independent parameters and their interactions were determined by ANOVA. By means of numerical optimization, the optimal values of the selected parameters equal to 1.34 g/L of catalyst, concentration of 16.45 mg/L, pH = 10.74, and light intensity of 15.53 W were obtained as optimal conditions with a desirability coefficient of 1.00 and an absorption value of 89.34%. The closeness of adjusted R2 (0.9838) and predicted R2 (0.9507) values show that this model can be successfully used for prediction.

Numerical simulation of deuterium retention in tungsten under ELM-like conditions

Retention of hydrogen isotopes (HI) in plasma-facing components (PFCs) is a crucial process influencing the operation of a fusion device. The dynamics of HI retention is mainly determined by irradiation conditions of PFCs. These conditions can change due to the onset of fast transient events, such as edge-localised modes (ELMs). The development of ELMs results in repetitive short-term plasma bursts on PFCs, affecting the exposure regime. In this work, the effect of ELM-like loads on the fuel retention is numerically analysed using a one-dimensional diffusion model, implemented in the FESTIM code. As a representative simulation case, the deuterium (D) retention in tungsten (W) is considered with the geometry and inter-ELM exposure conditions relevant for large fusion devices. Temporal dependencies of heat and particle fluxes during intra-ELM stages are accounted for by applying the free-streaming model for an ELM filament transport. The simulations were conducted for three inter-ELM exposure regimes with various properties of transient loads, D trapping sites, and D recombination rates. Compared to the ELM-free irradiation, the onset of transients is shown to mainly reduce the D retention rate because of significant material heating induced by the arrival of energetic ELMy particles. This relative difference can decrease if the material is characterised by strong trapping sites or limited desorption from a surface. The findings also demonstrate that additional heating during transients provides conditions for a faster D migration into the bulk. In addition, we discuss the possibility of using ELM-average loads to obtain quick assessments of the D content. The approach is shown to be applicable for the case of small ELMs and is used to derive the analytical expressions for the D distribution in W within the steady-state approximation.

Effectively enhanced photocatalytic hydrogen production performance of novel noble metal-free Cu(OH)2/MoSe2-g-C3N4 ternary nanocomposite under visible light irradiation

The present work presents a novel copper hydroxide-molybdenum diselenide-carbon nitride (3 % Cu(OH)2/MoSe2-g-C3N4, (3CM-CN)) ternary nanocomposite catalyst. This catalyst was synthesized using a three-step process: hydrothermal synthesis, ball milling, and wet impregnation. The focus of this research is on the hydrogen generation (H₂) capabilities of this novel material. The catalyst was extensively characterized using various analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet–visible (UV–Vis) spectroscopy, photoluminescence (PL) spectroscopy, and X-ray photoelectron spectroscopy (XPS), resulting in a comprehensive understanding of its structure, morphology, optical properties, and surface composition. The catalytic activity and mechanism of Cu(OH)2/MoSe2-g-C3N4 composites were investigated. The ternary nanocomposite catalyst significantly enhanced hydrogen production, achieving rates 7.7 times greater than g-C3N4 and 4 times greater than 3 % Cu(OH)2/MoSe2 (3CM). Its maximum production reached an impressive 3012 µmol g−1 h−1. The analysis demonstrated a significant increase in active sites on the composite’s surface, accompanied by an increase in the composite-specific surface area to 73 m2/g. The development of a ternary nanocomposite led to a higher rate of catalyst production for hydrogen generation while simultaneously decreasing the rate of electron-hole recombination. It gave an innovative strategy for constructing highly efficient composite catalysts for hydrogen generation very effectively.

Photophysical properties of donor (D)-acceptor (A)-donor (D) diketopyrrolopyrrole (A) systems as donors for applications to organic electronic devices.

Fourteen substituted diketopyrrolopyrrole (DPP) molecules in a donor (D)-acceptor (DPP)-donor (D) arrangement were designed. We employed density functional theory, time-dependent DFT, DFT-MRCI and the ab initio wave function second-order algebraic diagrammatic construction (ADC(2)) methods to investigate theoretically these systems. The examined aromatic substituents have one, two, or three hetero- and non-hetero rings. We comprehensively investigated their optical, electronic, and charge transport properties to evaluate potential applications in organic electronic devices. We found that the donor substituents based on one, two, or three aromatic rings bonded to the DPP core can improve the efficiency of an organic solar cell by fine-tuning the highest occupied molecular orbital/lowest unoccupied molecular orbital levels to match acceptors in typical bulk heterojunctions acceptors. Several properties of interest for organic photovoltaic devices were computed. We show that the investigated molecules are promising for applications as donor materials when combined with typical acceptors in bulk heterojunctions because they have appreciable energy conversion efficiencies resulting from their low ionization potentials and high electron affinities. This scenario allows a more effective charge separation and reduces the recombination rates. A comprehensive charge transfer analysis shows that D-A (DDP)-D systems have significant intramolecular charge transfer, further confirming their promise as candidates for donor materials in solar cells. The significant photophysical properties of DPP derivatives, including the high fluorescence emission, also allow these materials to be used in organic light-emitting diodes.

Investigation into the impact of anionic substitution on modulating the optical and catalytic properties of bismuth ferrite nanoparticles

Bismuth ferrite (BFO) nanoparticles have emerged as a non-toxic catalyst with remarkable potential for the photodegradation of various environmental pollutants. A notable departure from conventional approaches, where cations are added as dopant, this study achieved enhanced catalytic performance through anion substitution. Specifically, replacing oxygen atoms with nitrogen introduces spin-polarized defect states within the BFO’s energy gap, resulting in a notable reduction in the energy band gap. Nitrogen doping of bismuth ferrite yields a novel material with exceptional capabilities for the photodegradation of methylene blue dye and the reduction of 4-nitrophenol. Comprehensive characterization, including X-ray diffraction, Fourier-transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy, has unequivocally confirmed the successful incorporation of nitrogen into the BFO nanoparticle lattice. Interestingly, field emission scanning electron microscopy analysis revealed no significant alteration in nanoparticle size after nitrogen doping. Meanwhile, UV-diffuse reflectance spectroscopy unveiled a distinct decrease in the energy gap upon nitrogen incorporation. The observed improvements in catalytic activities can be attributed to nitrogen ions, introduced as substitutes, effectively occupying the oxygen defects within the sample, thereby diminishing recombination centers for photogenerated charge carriers and decreasing recombination rates. Additionally, adsorption kinetics studies underscore the efficacy of the catalyst surface in adsorbing methylene blue and/or 4-nitrophenol, conforming to the Ho pseudo-second-order model. This study not only highlights the exciting potential of nitrogen-doped bismuth ferrite nanoparticles in environmental remediation but also sheds light on the intricate interplay between anion substitution, band structure modification, and catalytic performance enhancement.Graphical

Enhancement of photocatalytic activity by thermal annealing of Au, Ag, and Cu implanted TiN thin films

The paper presents an investigation on the optoelectronic and photocatalytic properties of titanium-nitride (TiN) thin films, modified through the introduction of metal ions (Au, Ag, and Cu) during implantation, followed by thermal annealing. Employing high-resolution microscopic and spectroscopic techniques, we examined the microstructural and compositional features of the films in detail. The films exhibited a crystalline structure with distinct columnar patterns, attributed to defect release and recovery during annealing. Furthermore, metal nanoparticles were detected in samples implanted with gold and silver ions, indicating coalescence processes, while no such particles were observed in the case of Cu ions. Post-implantation annealing also led to surface oxidation and the formation of anatase TiO2, with a coexistence of TiO2, TiN, metallic Au and Ag, and CuO phases in subsurface regions. Comparative optical measurements revealed significant changes in photoluminescence efficiency and photocatalytic response of modified TiN. All implanted samples showed reduced photoluminescence intensity compared to pristine titanium-nitride, with the Au-implanted film exhibiting the most significant decrease, due to the presence of surface Au nanoparticles, thus resulting in the slower electron-hole recombination rates and enhanced photocatalytic activity.

Temperature affects recombination rate plasticity and meiotic success between thermotolerant and cold tolerant yeast species.

Meiosis is required for the formation of gametes in all sexually reproducing species and the process is well conserved across the tree of life. However, meiosis is sensitive to a variety of external factors, which can impact chromosome pairing, recombination, and fertility. For example, the optimal temperature for successful meiosis varies between species of plants and animals. This suggests that meiosis is temperature sensitive, and that natural selection may act on variation in meiotic success as organisms adapt to different environmental conditions. To understand how temperature alters the successful completion of meiosis, we utilized two species of the budding yeast Saccharomyces with different temperature preferences: thermotolerant Saccharomyces cerevisiae and cold tolerant Saccharomyces uvarum. We surveyed three metrics of meiosis: sporulation efficiency, spore viability, and recombination rate in multiple strains of each species. As per our predictions, the proportion of cells that complete meiosis and form spores is temperature sensitive, with thermotolerant S. cerevisiae having a higher temperature threshold for successful meiosis than cold tolerant S. uvarum. We confirmed previous observations that S. cerevisiae recombination rate varies between strains and across genomic regions, and add new results that S. uvarum has higher recombination rates than S. cerevisiae. We find that temperature significantly influences recombination rate plasticity in S. cerevisiae and S. uvarum, in agreement with studies in animals and plants. Overall, these results suggest that meiotic thermal sensitivity is associated with organismal thermal tolerance, and may even result in temporal reproductive isolation as populations diverge in thermal profiles.

Preparation of MoS2/V2O5 nanocomposites for ciprofloxacin degradation and Cr (VI) reduction

In this study, MoS2/V2O5 nanocomposites are obtained by hydrothermal process, and used for photocatalytic system of Ciprofloxacin (CIP) degradation and Cr (VI) reduction. Owing to its novel characteristics, MoS2/V2O5 heterojunctions are revealed as potential semiconductors in this region. V2O5 photocatalyst acts as a charge acceptor, meantime MoS2 acts as an electron donor, therefore promoting charge carrier separation and enhancing photocatalytic efficiency. The MoS2/V2O5 nanocomposites displayed enhanced photocatalytic CIP (98.7 %) and Cr (VI) reduction (98.8 %) after 120 min and 100 min of visible light activity. In contrast, in the first cycle, the photocatalysis capability of the photocatalyst performed in six cycles is 93.8 %. The Kapp values of MoS2/ V2O5 nanocomposites displayed about 11.2 and 19.5-times improvement of photocatalytic of CIP degradation and Cr (VI) reduction, respectively. The MoS2/V2O5 nanocomposites exhibited an enhanced photocurrent density of 0.082 μA/cm−2 compared to a pristine MoS2 sample of 0.045 μA/cm−2. The distinguished heterojunction photocatalysis performance is due to the significant migration of interfacial charges and the inhibited recombination rate of electron-hole pairs. CIP Pollutants eventually decay into H2O, CO2, and small molecule intermediates by generating •O2-, •OH, and h+. The influences of reactive radicals follow the order of •O2- radicals > h+ radicals > •OH radicals. Then, the probable structures of intermediates and achievable photodegradation pathways were discussed for the removal of CIP and Cr (VI) reduction using nanocomposite with visible light response.

Enhanced performance of hierarchical heterostructures CuS@ZnS-Ag-doped core–shell quantum dots towards photocatalytic degradation of pesticide contaminants in aqueous solution

ABSTRACT In recent years, the pollution of the water by pesticides has become a significant global concern due to the harmful effects these compounds have on human health and the environment. Therefore, removal of pollutants or making them ineffective is necessary for life. In this study, removal of agricultural pesticides such as Deltamethrin, Flumethrin and Phoxim was performed through photodegradation process using CuS@ZnS-Ag quantum dots as photocatalyst. The synthesised CuS@ZnS-Ag heterojunction nanocomposite has suitable charge separation and low electron–hole recombination rate with good optical properties. The synthesised photocatalyst was characterised by various techniques such as X-ray diffraction, Fourier transform infrared spectrometry, UV-Visible spectroscopy, field emission scanning electron microscopy and transmission electron microscopy. The effects of pH, temperature, photocatalyst dose and agitation rate on the degradation were investigated. The optimised conditions were obtained as follows: pH 7 (±0.5), temperature 30 (±2) °C, photocatalyst dose for Flumethrin 30 mg/L, Deltamethrin 10 mg/L and Phoxim 15 mg/mL and agitation rate 500 rpm. Results showed that under optimal conditions, the CuS@ZnS-Ag as photocatalyst can degrade 96% of the pollutants using light-emitting diode lamp. Kinetic studies indicated the pseudo-second-order model.