Linear Increment Research Articles

Integer multi-wavelength gradient phase metagrating for perfect refraction: Phase choice freedom in supercella).

Phase gradient metagratings (PGMs) reshape the impinging wavefront though the interplay between the linear adjacent phase increment inside supercells and the grating diffraction of supercells. However, the adjacent phase increment is elaborately designed by tuning the resonance of each subcell at a certain target frequency, which inevitably confines PGMs to operate only at the single frequency in turn. We notice that there exists a freedom of phase choice with a multi-2π increment in a supercell of PGMs, whereas conventional designs focus on the 2π increment. This freedom can induce a collaborative mechanism of surface impedance matching and multi-wavelength subcells, enabling the design of PGMs at multi-wavelengths. We further design and fabricate a supercell consisting of eight curved pipes to construct the two-wavelengths PGMs. The linear adjacent phase gradient of 0.25π at the fundamental frequency 3430 Hz is achieved, while the almost perfect transmission effect is observed due to the impedance match at the ends of curved pipes. In addition, the transmission field at the double frequency 6860 Hz is measured, whose refraction direction is consistent with that at 3430 Hz. This design strategy originated from phase choice freedom in the supercell and the experimental fabrication might stimulate applications on other multi-wavelength metasurfaces/metagratings.

Grain Quality Responses of Durum Wheat (<i>Triticum turgium</i> L. var. durum) to N Fertilizer and Seed Rates

In Ethiopia, knowledge about integrated seed and N fertilizer rates aimed at increasing the nutritional quality of durum wheat is limited. To full fill this gap, four levels of seed rate (i.e. 100, 125, 150, and 175 kg ha<sup>-1</sup>) and four levels of N rate (i.e. 0, 46, 92, and 138 kg ha<sup>-1</sup>) were arranged in randomized complete block design under two growing locations (environments). Results showed that the sole effects of the N fertilizer rate were a linear increment in hectoliter weight, gluten index (), and grain hardness under a high N rate. However sole effect of seed rate as well as the interaction effects of seed by N fertilizer rates did not have significant effects in all the tested grain nutritional qualities. On the other hand, interaction between the N rate and growing environment was found to be significant effects observed on the grain quality traits; grain protein content, wet, dry gluten, and gluten index were higher in Memirhager (low damp environment) combined with N application of 92 kg ha than Chefe Donsa site (high damp environment) even under higher N rate. The results of this research indicated that the aforementioned quality traits would be appreciably modified by N fertilizer, durum wheat should be grown in a low-damp environment. However, hectoliter weight, 1000-KW, and grain hardness were higher at the Chefe Donsa site. Therefore, an agronomist must consider the effects of nitrogen fertilizer, the environment, along their interaction, when aiming to optimize quality traits.

Revisiting the IR Spectra of H2S in an Argon Matrix: Identification of (H2S)n (n ≤ 4) Clusters via the Spectral Assignment of νS-H Transitions.

Small-molecular clusters of H2S up to tetramer have been experimentally identified in a cold and solid argon matrix by the spectral assignment of νS-H fundamental transitions for different H2S:argon mixing ratios. Normal-mode frequency calculations at the MP2-CP/aug-cc-pV(Q + d)Z level have been used to support the spectral assignments. In addition, modulations in relative populations of different clusters due to the annealing of the deposited matrix and the preheating of the H2S-argon gas mixture before deposition reinforced the spectral assignments. Variations in mixing ratio, annealing of the matrix, and preheating of the gas mixture have also been used, in a combined manner, to unambiguously identify the ν1 and ν3 bands of the H2S monomer, which has been a matter of dispute for a long period. The two bands have been identified at 2634.4 and 2648.0 cm-1, respectively, while three bands at 2581.5, 2568.4, and 2547.6 cm-1 have been assigned to H-bonded dimers, cyclic trimers, and cyclic tetramers, respectively. Multiple bands within 2550-2580 cm-1 have been assigned to caged tetramers. The cooperative strengthening of S-H···S H bonds in cyclic H2S clusters was evident from the linear increment in νS-H spectral shifts with cluster size.

Fabrication of CdSe/Si nanostructure for self-powered visible light photodetector

Self-powered visible light photodetector based nanostructured CdSe/Si geometry was fabricated using pulsed laser deposition (PLD). Herein, a detailed microstructural investigation was demonstrated in conjunction with the overall device photoresponsive performance. Particularly, an average particle diameter of 66.62 nm along optical band gap of 2.25 eV were attained. This was, subsequently, perceived in the fabricated device spectral response performance during which photocurrent (Iph) of 47 µA was attained under incident light of 575 nm and 6 mW/cm2, the nearest incident wavelength to the obtained optical band gap. At the reported incident light features, the proposed arrangement exhibited responsivity (Rλ) of 7.85 mA/W with light to dark current ratio (Iph/ID) of 998 %, respectively. Herein, the incident power variation suggested a linear increment (R2≈ 0.94) in both Iph and Iph/ID profiles, with values of 71 µA and 1501 %, respectively, at 575 nm and 26 mW/cm2. The fabricated device exhibited a pronounced time-resolved feature with rise/fall periods of 0.31 and 0.34 sec., while the power dependance based time-resolved behavior indicated a linear correlation between the stated factors with R2 value of 0.924, both of which were carried out at 0 bias voltage. The dual-singularity evidenced the self-powered feature of the proposed photodetector, where zero external potential is required.

Biocontrol potential of entomopathogenic nematodes against camel tick, Hyalomma dromedarii (Acari: Ixodidae)

Entomopathogenic nematodes (EPNs) are a well-established biocontrol agent for insect pests. Using such a bio-agent to eliminate ticks has only been reported in a few cases. The current study intended to determine how the camel tick, Hyalomma dromedarii Koch, 1844 (Acari:Ixodidae), engorged female, was affected by various concentrations and timing of exposure to infected juveniles of five EPN isolates from two species. The six groups of engorged females, each with 25 ticks, were subjected to five concentrations of 50, 100, 150, 300, and 600 infective juveniles (IJs)/female in order to perform the work. Female mortality was observed every day for up to 72 h. The groups' average weights were statistically equivalent. The following biological parameters: initial weight of the female (mg); pre- and oviposition periods (days); survival period (days); initial weight of the egg mass (mg); hatching percentage (%H); nutritional efficacy index (NEI); and the control efficacy (%) of the engorged females as influenced by Heterorhabditis indica NEM-23 and H. bacteriophora NEM-26 infections were also measured. The results showed a linear increment in female mortality with the increase in EPN concentrations. Three days after being exposed to H. bacteriophora at 300 or 600 IJs/Female, all H. dromedarii individuals died, while the group containing 50 IJs/Female of the same EPN reached 75 %. All biological parameters were altered by EPNs, and there were extremely noticeable variations between the concentrations and the untreated group. These findings indicate that both Heterorhabditis isolates acted negatively on the parameters that were being observed, encouraging one to believe that this EPN was effective in controlling engorged females of H. dromedarii in the laboratory.

Synthesis and thermoluminescence behavior of novel Sm3+ doped YCa4O(BO3)3 under beta irradiation

This study investigates the luminescent properties and dosimetric potential of YCa4O(BO3)3:0.5%Sm3+ phosphor synthesized via the combustion method. Dose-response investigations unveil a noteworthy linear increment in thermoluminescence (TL) intensity, emphasizing a remarkable linearity spanning a broad dose range from 0.1 to 300 Gy. Unusual heating rate effects are explored, revealing a shift in TL glow curve peak temperature (i.e 200 °C) towards higher temperatures with increasing heating rate. Speculative models, including Kinetic Trapping Effect, Thermal Quenching Compensation, and Defect Activation Energy Changes, are proposed. The study employs the Tmax-Tstop method to identify characterize glow curve peaks, and the Initial Rise method for the low-temperature segment analysis, revealing seven distinct trap levels at various depths within the bandgap. Glow curve deconvolution using the Complex Glow Curve Deconvolution (CGCD) method delineates a multi-peak structure, offering valuable insights into luminescent mechanisms. The model exhibits a Figure of Merit (FOM) of 1.71%, within an acceptable range, affirming its reliability. However, interpretation of the activation energy and frequency factor values suggests intricate site processes, necessitating a nuanced analysis to understand the material's luminescent characteristics. The YCa4O(BO3)3:0.5%Sm3+ phosphor demonstrates promising characteristics for precise dosimetry, with linear dose response, absence of saturation effects, and intriguing heating rate behavior.

Bactericidal effect of nanosilver synthesized with Neolitsea cassia mucilaginous extract

This study focused on green synthesis of silver nanoparticles using mucilaginous leaf extracts of Neolitsea cassia and demonstrating the bactericidal effect of the product against Staphylococcus aureus and Escherichia coli, which are common in polluted water. A concentration series of silver nitrate was subjected to four treatments by mixing with separate (a) aqueous and (b) 80% methanol extracts of N. cassia leaves in (c) atmospheric and (d) nitrogen gaseous environments, for comparison. A linear increment of the dry weight of silver nanoparticles was observed with increasing silver nitrate concentration (r = 0.99, p = 0), resulting in higher yields from 80% methanol extracts in an atmospheric environment. As characterized by surface plasmon resonance absorption, energy-dispersive X-ray spectroscopy and scanning electron microscopy, quasi-spherical crystalline silver nanoparticles of 11.7 nm average diameter were synthesized. The disk diffusion method showed that the growth of E. coli and S. aureus in culture media was increasingly inhibited with increasing nanoparticle concentration (r = 0.95, p = 0 and r = 0.93, p = 0, respectively). It was concluded that 80% methanol extract in an atmospheric environment was the most productive way to green-synthesize silver nanoparticles from the mucilaginous sap of N. cassia.

Asset Allocation for Retirement: Strategies for Risk Management and Growth

The US ex-president Franklin D. Roosevelt once famously said the test of our progress is not whether we add more to the abundance of those who have much, it is whether we provide enough for those who have too little. From the big picture, the aging problem has been or already slopped in many countries and regions. With the development of technology and healthcare, it is foreseeable to result in a longer lifetime and a healthier body, which should be good news for all human beings. However, the collateral costs are also unavoidably rising. By 2050, it is projected that one in six people in the world will be over the age of 65. This shift in demographics will have far-reaching social, economic, and political implications. Policies, like Social Security, National Pension System, National Insurance Scheme, etc., are all implemented based on the current economic environment, more to the point, the world is in a state of flux, and linear increment can never produce the order of magnitude achievements. To achieve real financial freedom, technical asset allocation may be a bite of the cherry, by financially operating retirement planning by almost any measure, can help to identify and mitigate more potential risks, achieve retirement goals and secure a financial future.

Numerical investigation of the velocity and spreading characteristics of non-circular turbulent jets at different Reynolds numbers

The flow field characteristics of non-circular turbulent jets are investigated numerically. A steady numerical simulation is conducted using the k–ε turbulence model in Ansys Fluent software. A hotwire anemometer is utilized to collect velocity data along the jet centerline for velocity validation. The jet exit Reynolds numbers vary from 200 to 5000, covering both laminar and turbulent regimes. The mean flow field characteristics, such as mean velocity, turbulent intensity, velocity decay, and half-jet spread width, are examined. The simulated results depict that mean velocity profile decay reveals a universal decay pattern, and the lateral velocity distribution shows a top-hat-like velocity profile in the near field. It significantly changed into peak-shaped and parabolic-shaped at a far downstream distance. The turbulent intensity profile reveals that shear layer growth begins near the jet exits, and entrainment becomes strong with the Reynold number. The potential core region increases with Reynolds numbers. The jet spread width shows a linear increment with the jet exit Reynolds number. The presented numerical results agree well with the measured experimental results and are consistent with published data.

Utilization of a new restoration technique for the rehabilitation of a degraded mangrove ecosystem: a case study from Koggala Lagoon, Sri Lanka

Mangrove ecosystems, amongst the most productive and biologically complex on Earth, are being degraded worldwide, and their widespread decline during the past decades has affected vital ecosystem services. Mangroves at Koggala lagoon on the southern coast of Sri Lanka have been degraded at an alarming rate due to agricultural practices, coastal zone development, and tourism activities. Most of the banks are heavily eroded due to boat and sea plane activities, and the mangrove ecosystem has been significantly damaged. Implementation of a scientific rehabilitation project was needed to restore this degraded mangrove ecosystem, and research was carried out to enrich the mangrove community by re-establishing mangroves on the eroded banks using corrosion-resistant plastic barrels. The sustainability of replanted mangroves was monitored under phase one and the re-establishment of ecological functions in the mangrove community was monitored under phase two. The accumulated biomass carbon during the period of two and half years was calculated by an allometric equation suggested for calculating biomass carbon of mangroves using the girth and height of individuals. The highest rate of girth increment was observed by the 24th month from establishment, whilst the growth rate declined between the 18th and the 30th months. During the study period, the average above-ground and below-ground biomass per barrel showed a linear increment. Our case study showed that the new method used for restoration is successful in establishing mangroves in sites with high erosion. This restoration technique was successful in coping with the situation in Koggala lagoon where previous restoration attempts were failures. Thus, we recommend this restoration method for sites facing the threat of severe erosion.

Chopped Areca Nut Fibers as Filler in Epoxy Matrix: Mechanical and Tribological Studies

In the current investigation, fibers extracted from the areca nut tree husk were either used unprocessed or processed with an alkaline treatment by being submerged in a 5 % sodium hydroxide solution. The average length of the areca fibers used in this work is 30 mm. Compression molding is used to create the composite out of an epoxy matrix with fibers added at 10, 15, 20 and 25 weight percent. The composites were tested for tensile strength, flexural modulus, Charpy impact, and shore D hardness, all of which showed the significant advantage acquired with quantity of fibers and fiber treatment. Pin on disc tribometer was used to conduct tribological tests on the treated fiber composites to analyse how the fiber-matrix bonding improved with an increase in fiber content. The primary shortcoming of the fibers is their relatively low elongation, which, even after treatment, hardly approaches 4 %. This indicates that the fibers are not uniform in length and prevents direct comparison to comparable composites containing a similar volume and length of natural fibers. The mechanical qualities of materials made with alkali treated chopped areca fibers where found to be enhanced when it was at 20 % volume fraction. A linear increment in values where observed in samples till 20 % volume fraction and a decrement with further increase in volume fraction. In the case of tribological evaluations, lesser values or wears were obtained at combination III for all the 3 loads, 10N, 15N and 20N. HIGHLIGHTS Three different amounts of fibers, namely 10, 15, 20 and 25 wt%, have been introduced in an epoxy matrix, fabricating the composite by compression molding. The composites were subjected to tensile, flexural, Charpy impact and Shore D hardness testing, which all demonstrated the considerable advantage obtained with quantity of fibers and fiber treatment, except in the case of hardness, where limited advantages were encountered. Also wear tests were carried out on treated fiber composites and surface morphology of the worn-out samples was studies, which demonstrated the improvement in fiber-matrix bonding obtained with the growing amounts of fibers. From the results on composites testing, it is evident that the areca nut husk fiber/epoxy polymer composites with an amount of short (30 mm length) random reinforcement introduced of 20 wt%, exhibits the highest peak mechanical properties among all the calculated properties. GRAPHICAL ABSTRACT

Nanomolar “Turn-On” Hg2+ detection by a fluorescein based fluorescent probe: DFT calculations, bioimaging and on-site assay kit studies

Sensitive yet rapid methodologies for efficient recognition of toxic heavy metals, like Hg2+, would avert the poisonous impacts of these elements on the environment and human health. Herein, we present a highly selective fluoresceine-based fluorogenic probe FP for Hg2+ recognition with quick response, an impressive LOD of 67.1 nM, high sensitivity, and a linear emission increment relationship with Hg2+ concentration (0–20.0 μM). FP could specifically recognize Hg2+ and it exhibited a 250-fold emission enhancement at 515 nm to Hg2+, but no response to other common cations. The mechanism for FP-Hg2+ was completely examined through FTIR, 1H NMR, TOF-MS, and density functional theory (DFT) calculations. To examine naked-eye recognition of Hg2+, the FP-coated silica plates, and cotton swabs were productively manufactured for the sensing of Hg2+. Besides, FP was able to recognize Hg2+ in biological systems with excellent efficiency. Overall, ultra-fast recognition property of FP for Hg2+, high sensitivity, and selectivity of FP against Hg2+ could be conveniently utilized to prevent the toxicity of Hg2+.

Salt effects on the reactivity for ligand substitution reactions of [Ru(CN)5OH2]3− anion with two naphthalene substituted ligands (nitroso‐R‐salt and α‐nitroso‐β‐naphthol) in presence of Tetrapropylammonium bromide (Pr4NBr) and Sodium chloride (NaCl)

AbstractThe kinetics of the ligand exchange reaction between aquapentacyanoruthenate(II) [Ru(CN)5OH2]3− ion and naphthalene substituted ligands [α‐nitroso‐β‐naphthol (αNβN), and nitroso‐R‐salt (NRS)] has been studied in aqueous salt solutions of sodium chloride (NaCl) or tetrapropylammonium bromide (Pr4NBr) salt. The kinetics was monitored spectrophotometrically at 525 nm corresponding to the λmax of reddish‐brown‐colored substituted products, [Ru(CN)5(αNβN)]3− or [Ru(CN)5(NRS)]3−. Increasing the ionic strength of the reaction mixture using NaCl, exerted a negative salt effect on the rate of formation of naphthalene‐substituted products. At the same time, an increment in the concentration of Pr4NBr imparted a positive salt effect on the reaction. The observed rate constant (kobs) exhibits linear increment with respect to the concentration of NRS or αNβN while remaining invariant with variation in [Ru(CN)5OH2]3−. The computed activation parameters for NRS (∆H# = 24.55 kJ mol−1, Ea = 27.03 kJ mol−1, ∆G# = 87.83 kJ mol−1, and ∆S# = – 212.5 J K−1 mol−1) and αNβN ((∆H# = 17.33 kJ mol−1, Ea = 19.81 kJ mol−1, ∆G# = 87.87 kJ mol−1, and ∆S# = – 236.7 J K−1 mol−1) also support the proposed mechanism.

Воздействие климатических факторов на приросты сосны обыкновенной (Pinus sylvestris L.) на побережье Кандалакшского залива Белого моря

The purpose of this study is a comparative analysis of linear and radial increments of Scots pine (Pinus sylvestris L.) as a response to the growing conditions on the coast of the Kandalaksha Bay of the White Sea, as well as an evaluation of the temperature and precipitation influences of the current and previous growing seasons. These were applied to the conventional methods of measurement and data analysis. The dynamics of growth in height and diameter were employed as indicators of the stands' response to habitant conditions. A statistical analysis of the growth rates was performed, which vary depending on habitat type, as well as an assessment of the connection between biometric indicators of the stands and the amount of precipitation and mean temperature. The significant differences in the series of linear increment increases were found as distinctions between biotopes, but they were absent for the radial increment. Therefore, it is possible to monitor the typical behavior of tree diversity independent of the biotope type using radial growth series. This provides the foundation for a long-term retrospective analysis of environmental impact on the stands by using the annual rings of the trees without taking growing conditions into account. Precipitation was determined to be a limiting factor for radial and linear growth throughout the phenophase of internodal growth and early wood formation. Temperature was identified as a limiting factor for radial development only during the stages of late wood formation and resource accumulation for the following growing season. The high sensitivity of linear increases to climatic conditions was revealed, which makes it useful as a criterion for assessing the state of forest ecosystems over short time periods (up to 30 years). However, this, in turn, dictates the impossibility of forming long-term linear increment series, as for radial growth, which is a significant limitation of this method. The choice of linear or radial growth analysis methods is concluded to be determined by the goals of the intended study, i.e., monitoring forest ecosystems under current climate change conditions or long-term paleoclimate analysis. For citation: Koukhta A.E., Maksimova O.V., Kuznetsova V.V. Influence of Climatic Factors on Scots Pine (Pinus sylvestris L.) Growth on the Coast of the Kandalaksha Bay of the White Sea. Lesnoy Zhurnal = Russian Forestry Journal, 2023, no. 4, pp. 105–119. (In Russ.). https://doi.org/10.37482/0536-1036-2023-4-105-119

Sustainable management practices for durum wheat production: Analyzing specific agronomic interventions on productivity, grain micronutrient content, and quality

As compared with single agronomic crop management practices during grain formation, knowledge about integrated agronomic management practices on grain mineral composition and grain technological properties in durum wheat is limited. This knowledge is important for determining management strategies aimed at increasing grain yield without affecting grain nutritional quality. Integrated agronomic practices such as foliar nutrient application × seeding rate × varieties combined with growing locations were investigated to evaluate the dynamics of yield and grain quality traits. Two durum wheat varieties, three-level of micronutrients (i.e. control, FeSO4, and ZnSO4), and four levels of seeding rate (i.e. 100, 125, 150, and 175 kg ha−1) were arranged in split-split plot design under two different growing locations (environments). The main plots were assigned to the varieties, subplots to micronutrients, and sub-sub plots to the seeding rate treatments. Zinc and iron were applied in a form of ZnSO4 and FeSO4 at the early flowering stage, both at a rate of 25 kg ha−1. Results showed a linear increment in biomass (21.5%) and grain yield (23.5%) under a high seeding rate, even though the 1000-grain weight, the number of grains spike−1, spike length, and the number of grains spike−1 were decreased. Higher varietal and environmental response of seeding rate was observed between varieties. The grain protein content, gluten, and zeleyn index decreased as the seeding rate increased. Grain micronutrient content was significantly influenced by seeding rate and varietal difference. The grain protein content was higher in a dryland environment than in a wet environment. A combined use of density-tolerant varieties, high seeding rate, and foliar-based iron application can improve the grain yield from 2.01 to 3.20 t ha−1 under a potential environment. Hence, all stakeholders should consider the genotype (G), environment (E), management (M), and their synergies, as far as grain yield and quality are considered simultaneously.

Development of silver nanoparticles and aptamer conjugated biosensor for rapid detection of E. coli in a water sample.

A simple, rapid, and sensitive electrochemical biosensor based on a screen-printed carbon electrode (SPCE) was developed for onsite detection of E. coli in real time. This work analyzed the effect of aptamer conjugation and PBS buffer solution on the colloidal stability of the silver nanoparticles (AgNPs). Aggregations of the AgNPs after aptamer conjugation in PBS buffer were observed from the particle size distribution analysis. The AgNP-aptamer conjugation and its affinity towards E. coli (DH5α) were confirmed by UV-visible spectrophotometry, which showed a linear increment in the absorption with increasing E.coli concentration. The screen-printed carbon electrodes were modified by drop-casting of AgNPs, which were used as an effective immobilization platform for E. coli-specific aptamers. The modified electrode's surface modification and redox behavior were characterized using cyclic voltammetry. Finally, E. coli was detected using differential pulse voltammetry with an optimized incubation time of 15min. The developed biosensors showed a linear decrease in current intensity with an increase in the concentration of E. coli. The biosensor had a relative standard deviation (RSD) of 6.91% (n = 3), which showed good reproducibility. The developed biosensors are highly sensitive and have a limit of detection (LOD) as low as 150CFU/ml. The biosensor showed good selectivity for E.coli coli when comparing the signal response obtained for bacteria other than E.coli. Also, the biosensor was found stable for four weeks at room temperature and showed high recoveries from 95.27% to 107% during the tap water sensitivity validation.

Carotid intima-media thickness in adults with and without psoriasis - a nested case-control study from baseline data of ELSA-Brasil cohort.

There is a lack of consensus about the association between psoriasis (PSO) and carotid intima-media thickness (cIMT) in literature, since previous studies considered dermatologic clinic patients or general population. This study aimed to compare cIMT levels according to PSO in a sample of 10,530 civil servants form the ELSA-Brasil cohort study and analyze its association with the disease. The PSO cases and disease duration were identified by medical diagnosis self-reported at study enrollment. A paired group was identified by propensity score matching among all the participants without PSO. Mean cIMT values were considered for continuous analysis while cIMT above 75th percentile was considered for categorical analysis. Multivariate conditional regression models were used to analyze association between cIMT and PSO diagnosis, by comparing PSO cases against paired controls and overall sample without disease. A total of n = 162 PSO cases were identified (1.54%) and no difference in cIMT values was observed between participants with PSO and overall sample or control group. PSO was not associated with linear increment of cIMT (vs. overall sample: β = 0.003, p = 0.690; vs. matched controls: β = 0.004, p = 0.633) neither with increased chance of having cIMT above 75th percentile (vs. overall sample: OR = 1.06, p = 0.777; vs. matched controls: OR = 1.19, p = 0.432; conditional regression: OR = 1.31, p = 0.254). There was no relationship between disease duration and cIMT (β = 0.000, p = 0.627). Although no significant relationship between mild cases of psoriasis and cIMT was observed among a wide cohort of civil servants, longitudinal investigation about cIMT progression and severity of disease are still needed.

Evaluating high temperature photoelectrocatalysis of TiO2 model photoanode

Sunlight concentration has been demonstrated as one promising strategy for practically photoelectrochemical (PEC) water splitting with exceeding 10% solar-to-hydrogen efficiency. However, the operating temperature of PEC devices, including the electrolyte and photoelectrodes, can be elevated to 65 ℃ naturally due to the concentrated sunlight and the thermal effect of near-infrared light. In this work, high temperature photoelectrocatalysis is evaluated using titanium dioxide (TiO2) photoanode as a model system, which is believed to be one of the most stable semiconductors. During the studied temperature range of 25–65 ℃, a linear increment of photocurrent density with a positive coefficient of 5.02 μA cm−2 K−1 can be observed. The onset potential for water electrolysis shows a significant negative shift by 200 mV. An amorphous titanium hydroxide layer and a number of oxygen vacancies generate on the surface of TiO2 nanorods, promoting the water oxidation kinetics. During long-term stability testing, the NaOH electrolyte degradation and TiO2 photocorrosion at high temperatures could cause the decaying photocurrent. This work evaluates the high temperature photoelectrocatalysis of TiO2 photoanode and reveals the mechanism of temperature effects on TiO2 model photoanode.

Sensitive detection of chromium (VI) using Au-NPs/MWCNT/chitosan composite via electrochemical approach

A glassy carbon electrode (GCE) was nanostructurally modified with a scaffold of gold nanoparticles (AuNPs), multiwalled carbon nanotubes (MWCNTs) and chitosan (Chit) for a sensitive detection of hexavalent chromium Cr(VI) in aqueous solutions. Each step of modification was analyzed and characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Strong interfacial adhesion between gold nanoparticles and porous nanostructure of MWCNTs-Chit was depicted. This scaffold uniformly distributed hydroxyl and carboxylate groups, as well as amine group throughout the surface of glassy carbon electrode, and gold nanoparticles adhered to carbon nanotubes wall inside the polymeric matrix. This scaffold selectively coordinated and preconcentrated the chromate ions for ulterior Cr(VI) detection. Under the optimized conditions (deposition potential: + 0.8 V vs. SCE, deposition time: 120 s), differential pulse voltammetry (DPV) electroanalysis results indicated the linear increment of electrochemical signals with an increase in the concentration of Cr(VI). Fabrication of a calibration curve was performed in a concentration range of 0.003–0.1 μg L−1 and limit of detection (LOD, 3σ/m) was calculated as 0.007 μg L−1. This nanostructured electrochemical sensor coupled with differential pulsed voltammetry, constitutes a very effective prospective capable of high sensitivity, selectivity, precision, accuracy, and rapid trace determination of hexavalent chromium ion in aqueous medium.

Optimized preparation and dyeing of Pterocarpus santalinus waste extract for enhancing healthy and environmental care performance of wool fabric

P. santalinus waste powders were utilized to prepare the aqueous extracts for the dyeing of wool fabric. The extraction and dyeing processes of P. santalinus were optimized for obtaining the dyed fabric with high color strength and flavonoids content. The antibacterial, antioxidant and aqueous Cr(VI) removal capacity of the dyed fabric was then examined and compared with other two plant (P. tinctorius and Lycium ruthenicum Murray) material extract dyed wool fabrics. The results indicated that the addition of ethanol in aqueous solvent could increase the content of colorants and flavonoid compounds in P. santalinus extract when soxhlet apparatus was used. The highest extraction effectiveness of P. santalinus was achieved at ethanol concentration of 80%. High dyeing temperature or low pH level caused an almost linear increment in color strength and flavonoid content of the dyed fabric. Optimum dyeing of wool fabric could be conducted when 35 mL of P. santalinus extract was used to prepare 100 mL of dyeing bath. The dyed fabric not only showed unique color, but also presented better antibacterial, antioxidant and Cr(VI) removal capacity, which were higher than those of the other two dyed fabrics. Increasing color strength or flavonoid content could enhance their functionalities.