Sharp Peak Research Articles

Application of artificial neural network for the mechano-bactericidal effect of bioinspired nanopatterned surfaces.

This study aimed to calculate the effect of nanopatterns' peak sharpness, width, and spacing parameters on P. aeruginosa and S. aureus cell walls by artificial neural network and finite element analysis. Elastic and creep deformation models of bacteria were developed in silico. Maximum deformation, maximum stress, and maximum strain values of the cell walls were calculated. According to the results, while the spacing of the nanopatterns is constant, it was determined that when their peaks were sharpened and their width decreased, maximum deformation, maximum stress, and maximum strain affecting the cell walls of both bacteria increased. When sharpness and width of the nano-patterns are kept constant and the spacing is increased, maximum deformation, maximum stress, and maximum strain in P. aeruginosa cell walls increase, but a decrease in S. aureus was observed. This study proves that changes in the geometric structures of nanopatterned surfaces can show different effects on different bacteria.

Effect of using MgO coating with multiple coatings on the optical properties of a five-layer stack

تم استخدام المادة العازلة MgO ذات معامل الانكسار العالي (H) 1.737 مع أربعة مواد عازلة BaF2 (فلوريد الباريوم) و Al2O3 (الألومينا) و GdF3 (فلوريد الجادولينيوم) و LaF3 اللانثانوم فلورايد ذوات معامل انكسار واطيء (L) 1.4825 و 1.5322 و 1.59 و 1.6056 على التوالي كطلاءات بصرية لخمس طبقات وللتصميمين الأول هو ((Glass/H/L/H/L/H والثاني (Glass/L/H/L/H/L) ، باستخدام برنامج MATLAB. تم حساب الخصائص البصرية (M، Rvis.، Rsol.، Tsol.) للطلاءات البصرية الأربعة المتكونة ، وذلك لمعرفة أي طلاء منها كفوء لتلوين زجاج الأنظمة الشمسية المستخدمة كواجهات للأبنية وأيها غير كفوء. تظهر النتائج أنه في التصميم الأول (Glass/H/L/H/L/H) للطبقات الخمس ، يوجد طلاءان فقط لهما كفاءة للتلوين ، وهما الطلاءان (MgO + BaF2) و (MgO + Al2O3) ، لأنهما يحققان القيم المطلوبة من عامل الجدارة (M) والانعكاسية المرئية Rvis. حيث ان القيم المطلوبة لقيم عامل الجدارة (M) و.Rvis والتي تجعل الطلاء كفوءاً للتلوين هي 6% و12% على التوالي ، ولهما قمة انعكاس منتظمة وحادة للتلوين في المنطقة المرئية. في التصميم الأول ، يتناسب معامل الانكسار عكسياً مع الخصائص البصرية للطلاء وبالتالي كفاءة تلوين الطلاء ، مما يعني أن طلاء (MgO + BaF2) أكثر كفاءة من طلاء (MgO + Al2O3) للتلوين. يعتبر التصميم الثاني (Glass/L/H/L/H/L) للطبقات الخمس غير كفوء للتلوين للطلاءات الأربعة ( (MgO + BaF2 ، (MgO+ Al2O3) ، (MgO + GdF3) ، MgO + LaF3)) لأنها لا تمتلك القيم المطلوبة من (M) و . Rvis

Raman Study of Novel Nanostructured WO3 Thin Films Grown by Spray Deposition.

The present communication reports on the effect of the sprayed solution volume variation (as a thickness variation element) on the detailed Raman spectroscopy for WO3 thin films with different thicknesses grown from precursor solutions with two different concentrations. Walls-like structured monoclinic WO3 thin films were obtained by the spray deposition method for further integration in gas sensors. A detailed analysis of the two series of samples shows that the increase in thickness strongly affects the films' morphology, while their crystalline structure is only slightly affected. The Raman analysis contributes to refining the structural feature clarifications. It was observed that, for 0.05 M precursor concentration series, thinner films (lower volume) show less intense peaks, indicating more defects and lower crystallinity, while thicker films (higher volume) exhibit sharper and more intense peaks, suggesting improved crystallinity and structural order. For higher precursor concentration 0.1 M series, films at higher precursor concentrations show overall more intense and sharper peaks across all thicknesses, indicating higher crystallinity and fewer defects. Differences in peak intensity and presence reflect variations in film morphology and structural properties due to increased precursor concentration. Further studies are ongoing.

Exploring energy selection methods for robust biologically optimized carbon ion arc for head&neck cancer patients

BackgroundDue to the advantageous depth dose profile of carbon ion beams, carbon ion therapy is commonly applied in the form of intensity modulated particle therapy (IMPT) with few treatment fields. Carbon ion arc therapy (C-Arc) has recently been proposed to improve dose conformity and increase the dose-averaged linear energy transfer (LETd) inside the target to levels relevant for overcoming tumor radioresistance. In this work, we investigate different energy selection approaches for C-Arc, including a novel greedy energy layer refinement strategy.MethodsRobust biologically optimized C-Arc plans were generated for six head &neck cancer patient previously treated at the Shanghai Proton and Heavy Ion Center (SPHIC). Different heuristic approaches for mono- and dual-energy C-Arc were implemented, and compared to carbon IMPT pans. A novel greedy energy layer refinement was developed, acting directly on the dose influence matrix, rather than on an iterative plan optimization. A key challenge in C-Arc with few energy layers per angle is the sharpness of the carbon ion Bragg peak, which is challenging for plan robustness. To improve robustness and plan quality, we propose the use of a 6 mm ripple filter instead of the typical 3 mm ripple filter used for carbon IMPT.ResultsMost mono-energetic C-Arc plans were able to meet the established clinical goals, but some of the heuristic energy selection schemes were not universally applicable with low plan quality in some patients. The developed energy layer refinement strategy delivered high quality plans even for complex cases. Mono-energetic C-Arc plans presented an average increase between 10% and 33% in the maximum LETd in the target, with similar or up to 19% improved average target LETd50%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{50\\%}$$\\end{document} compared to the IMPT carbon ion plans. C-Arc plans with 2 energies per treatment angle, for the employed energy selection heuristic, improved dosimetric quality compared to mono-energetic C-Arc plans, but did not provide the same natural improvement in LETd compared to IMPT.ConclusionsFor small, centrally located targets C-Arc demonstrates the greatest potential, but feasible plans could also be achieved for more complex cases in this work. Further development is necessary for improving C-Arc delivery efficiency and plan quality toward possible clinical application.

Synthesis, Characterization, Acute Dermal Toxicity, Anti-inflammatory, and Wound Healing Potential of Biogenic Silver Nanoparticles in Balb C Mice.

The current study aimed to develop an economic plant-based therapeutic agent to improve the treatment strategies for diseases at the nano-scale. In the current research, silver nanoparticles were synthesized using Trillium govanianum aqueous extract. Characterizations were done using UV-visible spectrophotometer, X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. In vivo biological activities such as acute dermal toxicity, wound healing, and anti-inflammatory were done on Balb C mice. Absorbance at 295 nm corresponds to the out-of-plane quadrupole Plasmonresonance while at 350 nm corresponds to in-plane dipole resonance. SEM images showed the morphology of TGAgNPs is not exactly spherical while XRD analysis shows that highly crystalline TGAgNPs with an average size of 27.94 nm. The FTIR spectrum represents sharp peaks of aldehyde, amide I, aromatic rings, and polysaccharides. The microscopic assessment did not find any epidermal and dermal layer abnormalities in Blab C mice when exposed to TGAgNPs during acute dermal toxicity. Results revealed that 1000 mg/kg is not a lethal dose. In the wound healing activity, no mortality and no abnormal signs were observed when petroleum jelly, nitrofuranose, TGaqu, and TGAgNPs-based ointments were applied. Enhanced epithelization was recorded in TGaqu and TGAgNPs treated mice (p≤0.001). The wound contraction percentage was higher in nitrofuranose-treated mice (74%) followed by TGAgNPs (71%), and TGaqu (69%) compared to vehicle-treated and open-wounded mice. The paw edema model proved the potential use of TGAgNPs and TGaqu as anti-inflammatory agents. Hence, the results proved that both TGaqu and TGAgNPs are not toxic and possessed strong anti-inflammatory and wound-healing effects due to the presence of phytochemical constituents and could be used in various drug production as a therapeutic agent.

Fully automated operational modal identification based on scale-space peak picking algorithm and power spectral density estimation

Modal analysis is a fundamental and essential research direction in the field of structural engineering. The ultimate goal is to determine the modal parameters of the structures. However, the existing modal analysis algorithms often require a large number of parameter adjustments and manual intervention during operation, which cannot be fully automated. In order to realize the automatic identification of modal parameters, the automatic operational modal identification method (AOMI) is proposed based on the interpolated power spectral density estimation (IPSE). To achieve more precise spectrum analysis in the low-frequency band, IPSE is employed to perform Fourier transform on the original frequency domain segment with optimized frequency resolution. This enhances the sharpness of the obtained spectrum in the low-frequency range, making peak frequencies more discernible. Subsequently, the scale-space peak picking algorithm is used to automatically obtain the peak of the power spectral density (PSD), thus enabling the automatic identification of the natural frequency. Finally, the frequency domain decomposition method (FDD) is used to identify modal parameters based on the natural frequencies. The effectiveness of AOMI is verified through the modal identification of the old steel truss bridge and the three layer framework. Under the environmental excitation, the frequencies identified by the IPSE method is close to that of FDD, Bayesian fast fourier transform (FFT) and covariance driven stochastic subspace identification (SSI-COV). Furthermore, the PSD obtained through IPSE has sharper peak than that of FDD and the Welch’s method. The damping ratio identification accuracy and modal assurance criterion (MAC) are satisfactory in AOMI, which can improve the automatic performance.

Optimizing the structural, thermal, gas sensing and electrical properties of in-situ polymerized poly(thiophene-co-indole)/silicon carbide nanocomposites for energy storage applications

Conducting copolymer nanocomposites of thiophene and indole incorporated with silicon carbide nanoparticles [poly (thiophene-co-indole-SiC) (PPSiC)] has been developed by in-situ copolymerization and these nanocomposites were characterized by different analytical techniques. The FTIR peak at 865 cm−1 signifies the successful incorporation of SiC nanoparticles in the copolymer matrix. The intensity of the UV-Vis absorbance of the copolymer nanocomposites increased with the nanoparticle concentrations, and PPSiC7 showed the highest intensity. This was in correlation with its low optical bandgap energy (3.032 eV) and high refractive index (2.388) value. XRD revealed the consistent positioning of sharp and distinct crystalline peaks of SiC in the copolymer. SEM revealed the effective dispersion of nanoparticles throughout the matrix and uniform dispersion was obtained for PPSiC7 nanocomposite. HR-TEM images validated the presence of spherical-shaped particles in the nanocomposite with the nano-size distribution of SiC. The surface roughness of the copolymer nanocomposite was evident from AFM analysis. TGA and DSC revealed that PPSiC nanocomposites have better thermal properties than the copolymer. AC conductivity increased with frequency and temperature. The PPSiC7 exhibits a maximum conductivity of 1.5×10−2 S/cm at 106 Hz and an activation energy of 0.064 eV. PPSiC nanocomposites demonstrated excellent results in degrading dye and detecting ammonia gas at ambient temperature. All analyses showed that the PPSiC7 nanocomposite exhibited superior properties than the copolymer. These admirable properties can be exploited in developing optoelectronic devices, energy storage devices and gas sensors.

Comparative Study on Structural, Dielectric Behavior and AC Conductivity of PPY-PVA Incorporated with TiO2 Fine and Nano Particles

Abstract An in-situ oxidative chemical polymerization technique to prepare thin films of PPY, PVA, and PPY-PVA blend doped with variable concentrations of TiO2 fine- and nano-particles was further investigated by X-ray diffractometer (XRD) and impedance spectrometer to study structural, dielectric, and AC conducting behavior. XRD spectra established that sharp and high intense peaks of PPY-PVA- fine TiO2 films indicated more crystallinity, which might be due to higher compactness and modification in interplanar spacing. Dielectric plots revealed that PPY-PVA-nano TiO2 films exhibited higher dielectric constants and lower dielectric loss compared to films of PPY-PVA- fine TiO2 in shorter frequency region, suggesting that these films are more suitable for charge storage devices. Conductivity plots revealed that AC conductivity of pure PPY was low (4.8 x10-3 S/cm at 313 0K) and was increased to 5.3 x10-3 S/cm by addition of PVA. AC conductivities of PPY-PVA-nano TiO2 thin films are relatively higher (7.43x10-3 S/cm to 1.14x10-2 S/cm) than PPY-PVA-fine TiO2 films (6.35x10-3 to 9.78x10-3 S/cm) with increasing frequency and temperature, which could be due to large surface area to volume ratio of nano-size dopant. This suggests that PPY-PVA-nano TiO2 thin films may be used for sensing various gasses.

Computational screening of silver-based single-atom alloys catalysts for CO2 reduction.

Electrocatalytically reducing CO2 into value-added products is a challenging but promising process. Catalysts have been proposed to reduce the potential necessary for the reaction to occur, among which single-atom alloys (SAAs) are particularly promising. Here, we employ density functional theory calculations and the computational electrode model to predict whether silver-based SAAs have the potential to be effective electrocatalysts to convert CO2 into C1 products. We take into account surface defects by using the Ag(211) surface as a model. We also verify whether the proposed materials are prone to OH poisoning or enhance the competing hydrogen evolution reaction. Our calculations predict that these materials show weak mixing between the host and the dopant, characterized by a sharp peak in the density of states near the Fermi energy, except when copper (also a coinage metal) is used as the dopant. This affects the adsorption energy of the different intermediate molecules, yielding different reaction profiles for each substrate. As non-doped silver, copper-doped SAA tends to spontaneously desorb carbon monoxide (CO) instead of proceeding with its reduction. Other elements of the fourth period (Fe, Co, and Ni) tend to bind to the CO molecule but do not favor more reduced products. These metals also tend to enhance the hydrogen evolution reaction. On the contrary, we show that the Ir and Rh dopants have significant potential as electrocatalysts, which favors the reduction of CO over its desorption while also suppressing the hydrogen evolution reaction at potentials lower than those required by copper. They have also been shown to not be prone to poisoning by OH radicals.

Monte Carlo study of magnetic behaviour of single Fe and Ni nanoparticles

ABSTRACT The exchange integral in the magnetic response of a spherical metallic iron (Fe) and nickel (Ni) nanoparticle is theoretically studied by using Monte Carlo simulations. To this end, using the nanoparticles model in spherical coordinates, we compute magnetization, magnetic susceptibility, specific heat, internal energy, and hysteresis loop over a wide range of temperatures for an Fe and Ni nanoparticle with a size of about 2 nm. The phase transition temperatures are interpolated versus the exchange parameters, and it is observed that the dependence on the coupling parameter is completely linear. Moreover, from the susceptibility results of the samples, the sharpest peak with the least fluctuation gives us the most appropriate Curie temperature and exchange integral for this system. However, the peak related to the heat capacity is also in the Curie temperature range. From the internal energy results, it can be understood that with the increase in phase transition and interaction, the system reaches equilibrium. The magnetic coercive field and remanent magnetization caused by nanoparticles indicate superparamagnetic properties at room temperature. At the end, the obtained results allow us to theoretically determine the magnetic properties of spherical nanoparticles and pave the way for the development of nanoparticles for many applications.

Derivative Spectroscopy and its Application at Detecting the Weak Emission/Absorption Lines

The development of spectroscopic survey telescopes like Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST), Apache Point Observatory Galactic Evolution Experiment and Sloan Digital Sky Survey has opened up unprecedented opportunities for stellar classification. Specific types of stars, such as early-type emission-line stars and those with stellar winds, can be distinguished by the profiles of their spectral lines. In this paper, we introduce a method based on derivative spectroscopy (DS) designed to detect signals within complex backgrounds and provide a preliminary estimation of curve profiles. This method exhibits a unique advantage in identifying weak signals and unusual spectral line profiles when compared to other popular line detection methods. We validated our approach using synthesis spectra, demonstrating that DS can detect emission signals three times fainter than Gaussian fitting. Furthermore, we applied our method to 579,680 co-added spectra from LAMOST Medium-Resolution Spectroscopic Survey, identifying 16,629 spectra with emission peaks around the Hα line from 10,963 stars. These spectra were classified into three distinct morphological groups, resulting in nine subclasses as follows. (1) Emission peak above the pseudo-continuum line (single peak, double peaks, emission peak situated within an absorption line, P Cygni profile, Inverse P Cygni profile); (2) Emission peak below the pseudo-continuum line (sharp emission peak, double absorption peaks, emission peak shifted to one side of the absorption line); (3) Emission peak between the pseudo-continuum line.

Photo-thermoelectric effect-driven detection of optical communication light in graphene/hBN heterostructures

We report on the photodetection properties of high-quality graphene encapsulated by hexagonal boron nitride under illumination with optical communication light. We demonstrate a gate-tunable photocurrent and zero-bias switching cycle operation at RT. Through gate and temperature-dependent photocurrent measurements, we determine that the dominant photoresponse mechanism is the photo-thermoelectric effect. At low temperatures, the photocurrent in finite doping regions correlates with the Seebeck coefficient, while sharp peaks emerge near the charge neutrality point due to an edge-excited photocurrent. Our study provides guidelines for high-performance graphene-based optoelectronic devices.

Enhanced photocatalytic degradation of methylene blue and methyl orange using biogenic ZnO NPs synthesized via Vachellia nilotica (Babool) leaves extract

Biogenic zinc oxide (b-ZnO) NPs were synthesized via the leaf extract of Vachellia nilotica (Babool) due to their rich source of bioactive complexes, which have great potential as a reliable, sustainable, and eco-friendly system. Sharp peaks in the XRD pattern of b-ZnO NPs confirmed the hexagonal wurtzite crystal structure. The crystallite size, D, of b-ZnO, decreased from 22.22 nm to 10.13 nm, and the lattice strain (τ) increased from 5.22 × 10−3 to 11.47 × 10−3 as the material changed from synthetic to biogenic, respectively. The Eg of b-ZnO was observed to be 3.37 eV. The specific surface area, total pore volume and average pore diameter of ZnO and b-ZnO NPs were increased from 9.5 to 34 m2/g, 0.3536–0.3854 cm3/g, and 17.24–19.56 nm, respectively. The photocatalytic degradation of b-ZnO increased from 72% to 80% for MO dye, from 87% to 93% for MB dye and completely degraded MB within 2 h. This work presents an essential advancement towards achieving enhanced photocatalytic performance to reduce water pollutants using b-ZnO and will guide the use of biogenic nanomaterials for photocatalytic applications.

Characterization and investigation of cytotoxicity and antimicrobial properties of coencapsulated limonene and thymol into the Ferula assafoetida gum microparticles

Thymol (Th) and d-limonene (L) exhibit low stability and are prone to oxidation when exposed to air, light, humidity, and high temperatures. This study examined the coencapsulation of Th and L into Ferula assafoetida gum (AFG) microparticles. Scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analyzer (TGA) were done to characterize the obtained complexes. Furthermore, the encapsulation efficiency, antibacterial properties, cytotoxicity, and anticancer properties of both the free and encapsulated forms of L and Th were measured. For all samples, by increasing the percentage of bioactive compound (L, Th, and L-Th) from 2.5 to 5 % w/w, the EE was increased. FTIR and XRD analysis results demonstrated that Th and L were successfully incorporated into the AFG. Additionally, thermogravimetric analysis showed that in the thermal graphs of all samples, the first weight loss occurred between 30 °C and 160 °C, which was due to the evaporation of water. In the free L and Th graph, a sharp reduction peak was observed in which 80 % of compounds were lost. These reduction peaks disappeared in the thermal graphs of L: AFG and Th: AFG revealing that the thermal stability of Th and L was significantly increased upon their incorporation into the AFG. The inclusion of Th into the AFG also led to an increase in its antibacterial activity, while L exhibited acceptable antibacterial activity, albeit not as high as Th. Additionally, according to the MIC results, Th: AFG had the best antibacterial activity among all compounds, especially on gram-positive bacteria. According to the result of the MTT assay, there was a significant difference between the IC50 of free Th (123.4 μg/ml) and Th: AFG (2312 μg/ml), and free L (1762 μg/ml) and L: AFG (2480 μg/ml) showing that encapsulated Th and L into the AFG has decreased the cytotoxicity of free compounds against L929 cell line. Also, Th: AFG had the best anticancer activity against Hella and CT26 cell lines among all compounds. Finally, the flow cytometry analysis demonstrated that the encapsulated particles effectively eliminated cancer cells. The outcomes imply that AFG can be employed as a suitable delivery system to enhance the use of Th and L into the food and pharmaceutical industries.

Multiwavelength Excitation in Ho3+-Doped All-Inorganic Double Perovskites Achieved by Codoping Mn2+ for Warm-White LEDs and Plant Growth.

Doping lanthanide ions is an efficient method to modify the optical properties of lead-free double-perovskite halides. However, most lanthanide-doped double perovskites show a low luminescence efficiency and require a high excitation energy. Here, we have successfully prepared a series of Ho3+-doped Cs2NaBiCl6 microcrystals through a simple hydrothermal method and obtained strong characteristic emissions of Ho3+ at 492 and 657 nm under low-energy excitation (449 nm). After codoping Mn2+, apart from the characteristic emissions from Ho3+ under 450 nm wavelength excitation, the orangish-red luminescence consisting of the emission band centered at 591 nm from Mn2+ and a sharp emission peak at 657 nm from Ho3+ is obtained under 355 nm UV light excitation. Photoluminescence (PL) emission and excitation spectra, along with the PL decay curves, confirm the existence of an energy-transfer channel from Cs2NaBiCl6 to Mn2+ and then from Mn2+ to Ho3+. The enhanced absorption efficiency (10.5 → 70.7%) suggests that the codoping of Mn2+ overcomes the low absorption efficiency caused by f-f forbidden transitions of Ho3+. Finally, the diverse luminescent performance within the Cs2NaBiCl6:Ho3+, Mn2+ phosphor is realized by altering the excitation wavelength, thereby enabling its application in warm-white-light-emitting diodes and plant growth in this work.

Enhanced dissolution rates of glibenclamide through solid dispersions on microcrystalline cellulose and mannitol, combined with phosphatidylcholine

Objective This study aimed to investigate the impact of physical solid dispersions of spray-dried glibenclamide (SG) on the surface of microcrystalline cellulose (MC) and mannitol (M) surfaces, as well as their combination with phosphatidylcholine (P), on enhancing the dissolution rate of glibenclamide (G). Methods Solid dispersions were prepared using varying proportions of 1:1, 1:4, and 1:10 for SG on the surface of MC (SGA) and M (SGM), and then combined with P, in a proportion of 1:4:0.02 using spray drying. The particle size, specific surface area, scanning electron microscopy (SEM), X-ray diffraction (XRD), and dissolution rate of SGA and SGM were characterized. Results SEM analysis revealed successful adhesion of SG onto the surface of the carrier surfaces. XRD showed reduced crystalline characteristic peaks for SGA, while SGM exhibited a sharp peaks pattern. Both SGA and SGM demonstrated higher dissolution rates compared to SG and G alone. Furthermore, the dissolution rates of the solid dispersions of SG, MC and P (SGAP), and SG, M, and P (SGMP) were sequentially higher than that of SGA and SGM. Conclusions The study suggests that physical solid dispersions of SG on MC and M, along with their combination with P, can effectively enhance the dissolution rate of G. These findings may be valuable in developing of oral solid drug dosage forms utilizing SGA, SGM, SGAP, and SGMP.

Jahn-Teller Distortions and Phase Transitions in LiNiO2: Insights from Ab Initio Molecular Dynamics and Variable-Temperature X-ray Diffraction.

The atomistic structure of lithium nickelate (LiNiO2), the parent compound of Ni-rich layered oxide cathodes for Li-ion batteries, continues to elude a comprehensive understanding. The common consensus is that the material exhibits local Jahn-Teller distortions that dynamically reorient, resulting in a time-averaged undistorted R3̅m structure. Through a combination of ab initio molecular dynamics (AIMD) simulations and variable-temperature X-ray diffraction (VT-XRD), we explore Jahn-Teller distortions in LiNiO2 as a function of temperature. Static Jahn-Teller distortions are observed at low temperatures (T < 250 K) via AIMD simulations, followed by a broad phase transition that occurs between 250 and 350 K, leading to a highly dynamic, displacive phase at high temperatures (T > 350 K), which does not show the four short and two long bonds characteristic of local Jahn-Teller distortions. These transitions are followed in the AIMD simulations via abrupt changes in the calculated pair distribution function and the bond-length distortion index and in X-ray diffraction via the monoclinic lattice parameter ratio, amon/bmon, and δ angle, the fit quality of an R3̅m-based structural refinement, and a peak sharpening of the diffraction peaks on heating, consistent with the loss of distorted domains. Between 250 and 350 K, a mixed-phase regime is found via the AIMD simulations where distorted and undistorted domains coexist. The repeated change between the distorted and undistorted states in this mixed-phase regime allows the Jahn-Teller long axes to change direction. These pseudorotations of the Ni-O long axes are a side effect of the onset of the displacive phase transition. Antisite defects, involving Li ions in the Ni layer and Ni ions in the Li layer, are found to pin the undistorted domains at low temperatures, impeding cooperative ordering at a longer length scale.

Production and characterization of cellulose acetate using olive tree pruning biomass as feedstock

AbstractOlive tree pruning (OTP) is one of the most abundant sources of biomass waste in the Mediterranean basin. This is especially relevant in southern Spain where olive oil production represents a large part of the economy. Olive tree prunings are mostly either burned or are spread in olive orchards as an organic amendment, or used for heat generation on a domestic scale. However, the lignocellulosic composition of OTP makes it a potential source of biopolymers, thus providing an excellent economic alternative for the olive oil sector. In this work, pretreated OTP fibers were subjected to an optimized alkaline treatment followed by a single‐step bleaching reaction with H2O2. Afterwards, the cellulose pulp was transformed chemically to obtain cellulose acetate. Noncellulosic components were removed effectively from OTP, thus obtaining a pulp highly purified in cellulose with 71% crystallinity and 355 °C maximum degradation temperature. Nevertheless, a very large amount of cellulose (ca. 50%) was eliminated throughout the process, especially during acid pretreatment, which was responsible for 38% solubilization. A similar level of acetylation and degree of substitution was obtained by using acetylation times in the range of 1 to 6 h. No large differences were observed in the infrared spectra and X‐ray diffractograms of the synthesized acetates. However, their thermal stability varied significantly with reaction time, evolving from a multistep degradation pattern to a single and sharp peak between 300 and 400 °C with increasing time. Thermogravimetric curves revealed that at least 5 h (preferably 6 h) were needed to obtain cellulose acetate from OTP with adequate thermal stability for further processing.

Optical, electrical and thermal investigations on brucinium di-hydrogen citrate tri-hydrate single crystal: An optimistic tool for microelectronics, OPO and OLED applications

Highly capable nonlinear optical brucinium di-hydrogen citrate tri-hydrate (BDHCTH) single crystal under organic material category has been grown-up successfully by slow evaporation method. Optical, electrical, and thermal investigations were made on title crystal to discover the suitability of fabrication of an optical as well as electrical device for the first time. Crystal structure analysis confirms that, the BDHCTH crystal belongs to triclinic crystal system with non-centro symmetric space group P1. The SLDT value of BDHCTH crystal was found to be 4.22 GW/cm2. Second harmonic generation efficiency of the BDHCTH compound is 1.08 times superior to the reference sample KDP. An attribution of single and sharp peak with lesser full width half maximum value confirms the presence of very fewer defects in the grown crystal. An electric response of the title compound shows the normal dielectric behavior. The piezoelectric charge co-efficient (d33) was found to be 4.5 p C/N. Photo luminescence study confirms that the synthesized sample possess violet, blue and red emission behaviors. Presences of various functional groups in the title sample were identified by FT-IR study. Thermal stability of the compound BDHCTH was found to be 135 °C. Kinetic parameters such as activation energy, Arrhenius factor, standard entropy of activation, standard enthalpy of activation, standard Gibb's energy of activation (ΔG*) and induction time of the grown sample were found to be 161.6396 k J mol−1, 7.4854 s−1, -230.8278 J K mol−1, 154.854 k J mol−1, 249.0314 k J mol−1 and 52 days respectively. At the end of an optical, electrical and thermal analysis, we concluded that the grown crystal is an optimistic tool for microelectronics, OPO and OLED applications due to existence of good SHG value, lesser defect and red emission behavior.

Green superabsorbent hydrogel derived from activated charcoal and glycerol with maleic acid as a cross-linker

Superabsorbent hydrogels characterize a set of polymeric materials with three-dimensional structures capable of absorbing large amounts of water due to their hydrophilic functional groups on their surface. Their application in industries, agriculture, and the environment is of primary significance. This study reports the synthesis and characterization of green superabsorbent hydrogels derived from activated charcoal. The process involved a polymerization reaction between activated charcoal (AC) with glycerol (G) using sodium hydroxide as an initiator in the absence and presence of maleic acid as a crosslinker to synthesize HCG-1 and HCG-2 superabsorbent hydrogel respectively. Characterization of the hydrogels was done using Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscope (SEM), and X-ray diffraction (XRD). Optimization conditions were done by synthesizing hydrogel with varying dosages of both activated carbon and maleic acid as well as swelling time. The FT-IR results showed the appearance of strong sharp peaks at 1591.34 cm-1 and 1400.28 cm-1 in HCG-1 associated with -COO¯ symmetric stretching and asymmetric bending vibrations, indicating interlink between reacting monomers. A new absorption band at 1639.48 cm-1 associated with -COO¯ bending in non-conjugated ester indicates ester-crosslink in HCG-2 hydrogel. XRD analysis showed a phase shift from semi-crystalline to crystalline structure upon crosslinking. SEM analysis showed a crystalline intact, rigid structure without voids and pores on its surface in HCG-1 compared to the smooth irregular pores and lamina structure observed in HCG-2 hydrogel. The dosage ratio of AC: G: maleic acid of 8:5:1 produced hydrogel with an optimal water absorption capacity of 1255.80±0.70%. Maleic acid was found to improve the water absorption capacity of the superabsorbent. The study is an eye opener towards the application of biodegradable hydrogels in agriculture, especially in semi and arid regions.