jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: K. Kurdziel | Marta Raczyńska-Żak | A. Kolbus
Source: Solvent Extraction and Ion Exchange (article, 2020-12-02)
Field: Materials Science — Biomaterials

Removal of Phenol and Monochlorophenols Pollution from Aqueous Solutions with HDTMA-Modified Halloysite Dynamic and equilibrium research on the adsorption of phenol and monochlorophenols (2-chlorophenol, 3-chlorophenol, 4-chlorophenol) on modified halloysite with the use of HDTMA (hexadecyltrimethylammonium) bromide was conducted at three temperatures: 293, 303, and 313 K. The interpretation of experimental data was based on the Temkin, the Dubinin-Radushkevich, the Freundlich, and the Langmuir equations to establish the appropriate adsorption models and to define the characteristic parameters describing the process. We determined that the Freundlich isotherm perfectly described experimental data as regards the adsorption equation concerning phenol; however, 2-chlorophenol, 3-chlorophenol, and 4-chlorophenol sorption took place in compliance with the Langmuir model. The adsorption of the studied compounds on the HDTMA-modified halloysite increased in the following order: phenol <4-chlorophenol <2-chlorophenol <3-chlorophenol. Thermodynamic parameters of the processes indicated the physical as well as exothermal adsorption character. The adsorption kinetics of phenol and monochlorophenols was discussed based on the following models: pseudo-first-order, pseudo-second-order, Elovich, intraparticle diffusion, and film-diffusion model. The rate of the sorption process was described with the pseudo-second-order model. The global electrophilicity indices of phenol and the monochlorophenols were applied to demonstrate the difference through the interaction of these adsorbates with a molecule of surfactant (HDTMA) and, as a result, the different properties of the studied compounds. Freundlich equation ; Chemistry ; Adsorption ; Sorption ; Langmuir ; Phenol ; Chlorophenol ; Aqueous solution ; Halloysite ; Diffusion ; Inorganic chemistry ; Chemical engineering ; Thermodynamics ; Organic chemistry Clay minerals and soil interactions ; Adsorption and biosorption for pollutant removal ; Iron oxide chemistry and applications
Authors: Chiara Piotto | Sidharam P. Pujari | Han Zuilhof | Paolo Bettotti
Source: Nanomaterials (article, 2020-08-24)
Field: Materials Science — Materials Chemistry

Surface Heterogeneous Nucleation-Mediated Release of Beta-Carotene from Porous Silicon We demonstrate that the release of a poorly soluble molecule from nanoporous carriers is a complex process that undergoes heterogeneous surface nucleation events even under significantly diluted release conditions, and that those events heavily affect the dynamics of release. Using beta-carotene and porous silicon as loaded molecule and carrier model, respectively, we show that the cargo easily nucleates at the pore surface during the release, forming micro- to macroscopic solid particles at the pores surface. These particles dissolve at a much slower pace, compared to the rate of dissolution of pure beta-carotene in the same solvent, and they negatively affect the reproducibility of the release experiments, possibly because their solubility depends on their size distribution. We propose to exploit this aspect to use release kinetics as a better alternative to the induction time method, and to thereby detect heterogenous nucleation during release experiments. In fact, release dynamics provide much higher sensitivity and reproducibility as they average over the entire sample surface instead of depending on statistical analysis over a small area to find clusters. Nucleation ; Dissolution ; Materials science ; Nanoporous ; Kinetics ; Chemical physics ; Chemical engineering ; Porosity ; Supersaturation ; Nanotechnology ; Chemistry ; Organic chemistry ; Composite material Anodic Oxide Films and Nanostructures ; Silicon Nanostructures and Photoluminescence ; Mesoporous Materials and Catalysis
Authors: Xiaobao Li | Xiaolong Zhou | Yanian Gao
Source: Micro & Nano Letters (article, 2020-11-01)
Field: Materials Science — Materials Chemistry

Formation mechanism of ZnO nanosheets combined with regenerated cellulose through NaOH inner‐pore diffusion process In the present work, regenerated cellulose films with different pore sizes were prepared using cellulose, which can control the synthesis reaction of nano‐ZnO and thus regulate its morphology. The results show that with 0, 4, and 8 g of cellulose applied, average pore sizes of samples increased from 7.0 nm to 14.4 and 20.1 nm, respectively. When no cellulose was used, only large Zn 5 (OH) 8 Cl 2 ·H 2 O (ZHC) flakes were prepared. Long ZnO nano‐sheets and ZHC flakes with a mass fraction of 0.51 and 0.33, respectively, were prepared by adding 4 g cellulose; and ZnO nano‐sheets with a mass fraction of 0.73, with 0.04 ZHC, were synthesised while using 8 g cellulose. The results reveal that the addition of cellulose can improve the average pore diameter of films and enhance the reaction rate of ZnO, resulting in the formation of ZnO nano‐sheets/regenerated cellulose films. Chemical engineering ; Cellulose ; Diffusion ; Materials science ; Mechanism (biology) ; Process (computing) ; Chemistry ; Nanotechnology ZnO doping and properties ; Advanced Photocatalysis Techniques ; Copper-based nanomaterials and applications
Authors: Salaudeen Abdulwasiu Olawale | Olayinka Oluwaseun Oluwasina
Source: Open Access Journal of Chemistry (article, 2020-01-01)
Field: Chemistry — Analytical Chemistry

Kinetics Studies for the Adsorption of Aqueous Cu (II) and Pb (II) Ions onto Chicken Feather Adsorption kinetic studies are of great significance to evaluate the performance of a given adsorbent and to gain insight into the underlying mechanism.The sorption kinetics of Pb(II) onto chicken feathers (CF) was investigated.In order to understand the mechanisms of the biosorption process and the potential rate controlling steps, kinetic models were used to fit the experimental data.The results indicated that kinetic data were best described by the pseudo second-order model with a correlation coefficient (R 2 ) of 0.999 and 0.998 for Pb(II)/CF and Cu(II)/CF respectively.The experimental uptakes, q exp were much consistent with those calculated/obtained from the pseudo second order model.Biosorbents-Pb(II) kinetics follow the order: pseudo-second order > pseudo-first order > Weber-Moris intra particle diffusion model.The biosorbents also show a good reusability after simple elution with EDTA and HNO 3 . Feather ; Adsorption ; Aqueous solution ; Kinetics ; Chemistry ; Ion ; Nuclear chemistry ; Inorganic chemistry ; Physical chemistry ; Biology ; Physics ; Organic chemistry ; Ecology Dye analysis and toxicity ; Adsorption and biosorption for pollutant removal ; Water Quality Monitoring and Analysis
Authors: Н. В. Саутина | A. I. Rybakova | А.Т. Губайдуллин | Yu. G. Galyametdinov
Source: Liquid Crystals and their Application (article, 2020-06-30)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Liquid Crystal Mesophase of the Water / AOT / Isopropylmiristat System in the Processes of Transdermal Delivery of Amino Acids ЖИДКОКРИСТАЛЛИЧЕСКАЯ МЕЗОФАЗА СИСТЕМЫ ВОДА Transdermal ; Mesophase ; Liquid crystal ; Chemistry ; Delivery system ; Amino acid ; Materials science ; Organic chemistry ; Chemical engineering ; Medicine ; Pharmacology ; Biochemistry ; Engineering Liquid Crystal Research Advancements ; Surfactants and Colloidal Systems ; Lipid Membrane Structure and Behavior
Authors: Reem Alhasani | Taichi Yabe | Yutaro Iyama | Nobutaka Oi | Shoichiro Imanishi | Quang Ngọc Nguyễn | Hiroshi Kawarada
Source: Research Square (preprint, 2020-12-29)
Field: Materials Science — Materials Chemistry

An Enhanced Two-Dimensional Hole Gas (2DHG) C-H Diamond with Positive Surface Charge Model for Advanced Normally-Off MOSFET Devices Abstract Though the complementary power field effect transistore (FETs), e.g., metal-oxide-semiconductor-FETs (MOSFETs) based on wide badgap materials, enable low switching losses and on-resistance, p-channel FETs are not feasible in any wide bandgap material other than diamond. In this paper, we propose the first work to investigate the impact of fixed positive surface charge density on achieving normally-off and control threshold voltage operation obtained on p-channel two-dimensional hole gas (2DHG) hydrogen-terminated diamond (C-H) FET using deep nitrogen doping in the diamond substrate. In general, a p-channel diamond C-H MOSFET demonstrates normally-on operation, but the normally-off operation is also a critical requierment of the feasible electronic power devices in terms of safety operation. The evaluation results of the characteristic of the C-H MOSFET capacitor with the two demonstrated charge sheet models using the two-dimensional Silvaco Atlas TCAD show that the fixed-Fermi level is a function of capacitance-voltage with an activation energy of 1.7 eV (donor level) at the H-diamond surface close to minimum conduction band. The maximum current density with a positive surface charge model and a nitrogen-doped layer of the Al2O3/H-diamond device is -52 mA/mm at a gate-source voltage of -42 V. Also, the gate threshold voltage is relatively high at Vth= -3 V, i.e., the positive surface charge model can achieve the normally-off operation. Moreover, we demonstrate that the obtained results correspond to the experimental work with the SiO2 layer located below the gate in C-H diamond/Al2O3 surface. Diamond ; MOSFET ; Materials science ; Work function ; Threshold voltage ; Optoelectronics ; Doping ; Capacitance ; Voltage ; Nanotechnology ; Electrical engineering ; Chemistry ; Electrode ; Layer (electronics) ; Transistor Diamond and Carbon-based Materials Research ; Semiconductor materials and devices ; Metal and Thin Film Mechanics
Authors: Pryce M.J. | David Cheneler | A. Martin | Farid Aiouache
Source: Proceedings of the World Congress on Mechanical, Chemical, and Material Engineering (article, 2020-07-31)
Field: Materials Science — Polymers and Plastics

Mathematical Model Analysis for Mass and Rates of Woodchip IR Drying The production of woodchip biomass, by means of drying, is of importance with respect to environmental concerns. This has been highlighted by reports of carbon production through utility usage of commercial sites, where drying is often among the most energy intensive operations within industrial processes. It is therefore crucial to dry wood in efficient way in order to derive high quality products and increase end use process efficiency. A key component for dry fuel suppliers is the moisture content of the woodchip product. Halogen (infrared) drying is the foremost method used on site to measure moisture content of wood fuel for supply, as this takes less time, a smaller sample size and less human interaction, in comparison with convective drying. This study investigated the drying behaviour of static woodchip fuel using an infrared source at temperatures ranging from 50 to 80 and atmospheric pressure. With the longest drying time (time until a rate of 0.001g per 99 seconds is reached) of just over three hours and the shortest under an hour and a half. Mathematical models of the drying rates were determined through statistical analysis and the significance of the initial drying periods relevant to rates of falling and constant profiles were analysed for the different temperatures. Statistically the model with the best fit at the temperatures measured was a diffusion model with 6 exponential terms and coefficients with the SSE value 0.2424, R 2 of 0.9989 and RMSE of less than 0.009. Models with 4 coefficients were also able to fit the data well with SSE values of below 0.03. Differentiating the resulting equations of fit at constant temperature resulted in models for the rate of mass lost over time. Environmental science ; Computer science ; Process engineering ; Engineering Textile materials and evaluations ; Forest Biomass Utilization and Management ; Radiative Heat Transfer Studies
Authors: Maciej Łuszczek | Marek Turzyński | Dariusz Świsulski
Source: International Journal of Electronics and Telecommunications (article, 2020-12-02)
Field: Materials Science — Materials Chemistry

The Behavioural Model of Graphene Field-effect Transistor The behavioural model of a graphene field-effect transistor (GFET) is proposed. In this approach the GFET element is treated as a “black box” with only external terminals available and without considering the physical phenomena directly. The presented circuit model was constructed to reflect steady-state characteristics taking also into account GFET capacitances. The authors’ model is defined by a relatively small number of equations which are not nested and all the parameters can be easily extracted. It was demonstrated that the proposed model allows to simulate the steady-state characteristics with the accuracy approximately as high as in the case of the physical model. The presented compact GFET model can be used for circuit or system-level simulations in the future. Graphene ; Field-effect transistor ; Materials science ; Transistor ; Field (mathematics) ; Engineering physics ; Electronic engineering ; Optoelectronics ; Nanotechnology ; Electrical engineering ; Engineering ; Mathematics ; Voltage Graphene research and applications ; Advancements in Semiconductor Devices and Circuit Design ; Radiation Effects in Electronics
Authors: В. И. Миронов | I. G. Emel’yanov | Д. И. Вичужанин | Л. М. Замараев | D. A. Ogorelkov | V. V. Yakovlev
Source: Diagnostics Resource and Mechanics of materials and structures (article, 2020-02-01)
Field: Materials Science — Materials Chemistry

Effect of hydrogenation temperature and tensile stress on the parameters of the complete deformation diagram for steel 09G2S Hydrogen concentration in the sample material depends on its environmental content, external pressure, temperature, surface condition, and testing time. All other things being equal, increasing temperature increases the diffusion coefficient and, consequently, hydrogen concentration in the metal. This, in turn, changes the mechanical properties of the material. The paper considers the principal possibility of determining the parameters of this process within the method of complete deformation diagrams. By changing the parameters of the diagram of the hydrogenated metal, a conclusion is made about the changes in its strength, plasticity, and crack resistance. The approach is illustrated by the results of testing samples of the structural 092 steel, widely used in mechanical engineering. It has been found that the increasing temperature of hydrogenation reduces the strength and ductility of the steel and increases crack resistance. Thus, it is experimentally proved that the parameters of the falling branch of the complete diagram are sensitive to hydrogen concentration in the steel. The changes in the mechanical properties of the structural steel caused by the action of hydrogen are qualitatively similar to those caused by cyclic loading. In this regard, it is concluded that degradation processes of different natures can be studied on a common methodological basis. The parameters of the falling branch of the complete deformation diagram can serve as the representative parameters of these processes. Materials science ; Diagram ; Deformation (meteorology) ; Ultimate tensile strength ; Stress (linguistics) ; Composite material ; Metallurgy ; Mathematics ; Statistics ; Philosophy Material Properties and Failure Mechanisms ; Engineering Diagnostics and Reliability ; Material Properties and Applications
Authors: Rafailia A. A. Beta | Athanasios P. Kyritsis | Veroniki Douka | Eirini Papanastasi | Marianna Rizouli | D.D. Leonidas | Dimitriοs Vlachakis | Nikolaos A. A. Balatsos
Source: FEBS Open Bio (article, 2020-10-23)
Field: Chemistry — Spectroscopy

Biochemical and <i>in silico</i> identification of the active site and the catalytic mechanism of the circadian deadenylase HESPERIN The 24‐h molecular clock is based on the stability of rhythmically expressed transcripts. The shortening of the poly(A) tail of mRNAs is often the first and rate‐limiting step that determines the lifespan of a mRNA and is catalyzed by deadenylases. Herein, we determine the catalytic site of Hesperin, a recently described circadian deadenylase in plants, using a modified site‐directed mutagenesis protocol and a custom vector, pATHRA. To explore the catalytic efficiency of AtHESPERIN, we investigated the effect of AMP and neomycin, and used molecular modeling simulations to propose a catalytic mechanism. Collectively, the biochemical and in silico results classify AtHESPERIN in the exonuclease–endonuclease–phosphatase deadenylase superfamily and contribute to the understanding of the intricate mechanisms of circadian mRNA turnover. In silico ; Biology ; Circadian clock ; Mutagenesis ; Computational biology ; Mechanism (biology) ; Cell biology ; Genetics ; Mutation ; Gene Mass Spectrometry Techniques and Applications ; RNA and protein synthesis mechanisms ; Genomics and Chromatin Dynamics
Authors: Shabbir Hussain | Sadaf Sarfraz
Source: Lahore Garrison University Journal of Life Sciences (article, 2020-04-22)
Field: Chemistry — Organic Chemistry

Biological Potential and Structure Activity Relationships in Organotin (IV) and Pd(II) Compounds Organotin(IV) and palladium(II) complexes are mainly synthesized by treating a N,O or S donor ligand with an organotin halide and PdCl2, respectively. The structures of the complexes can be elucidated by various characterization techniques such as microanalysis (CHNS), FTIR spectroscopic analysis, UV-Visible spectroscopy, NMR (1H &amp; 13C) and single crystal XRD. Organotin compounds are applied in numerous biocidal formulations as wood preservatives, surface disinfectants, antitumor agents, insecticides, marine antifouling paints, mollucides, miticides and fungicides. The biochemical activity is mainly affected by coordination number of tin, number and nature of the organic group bonded to tin and the chain length of an alkyl groups. Organotin(IV) dithiocarbamates are famous for their acaricidal, antifungal, tuberculostatic, antibacterial and anticarcinogenic activities. Cisplatin which is a famous Pt(II) drug, is successfully applied either alone or in various combinations to treat cancer. However, There is also a growing interest in the discovery of alternate drugs with palladium(II) because there are considerable similarities between the coordination chemistry of palladium(II) and platinum(II) compounds. However, the palladium complexes dissociate readily and form reactive species which could not reach their pharmacological targets. This drawback can be overcome by synthesizing Pd(II) complexes with chelating ligands such as dithiocarbamates. Pd(II) and Pt(II) compounds with bioactive ligands are of special interest due to their possibility of oral administration, lower toxicity and their ability to coordinate with DNA. Organotin(IV) derivatives possess strong antibacterial and antifungal potential while palladium(II) complexes are chiefly famous for their antitumor and anticancer activities. The nature of a metal coordinated to the ligand, has a decisive role in biological activities of both kinds of compounds. Palladium ; Chemistry ; Chelation ; Ligand (biochemistry) ; Platinum ; Tin ; Coordination complex ; Semicarbazone ; Antifungal ; Stereochemistry ; Combinatorial chemistry ; Medicinal chemistry ; Organic chemistry ; Metal ; Catalysis Organometallic Compounds Synthesis and Characterization
Authors: C C Dykstra | R R Tidwell | Michael Cory | C A Bell | N A Naiman | T A Fairley
Source: UNC Libraries (article, 2020-10-30)
Field: Chemistry — Organic Chemistry

Structure-activity studies of dicationically substituted bis-benzimidazoles against Giardia lamblia: correlation of antigiardial activity with DNA binding affinity and giardial topoisomerase II inhibition. Nine dicationically substituted bis-benzimidazoles were examined for their in vitro activities against Giardia lamblia WB (ATCC 30957). The potential mechanisms of action of these compounds were evaluated by investigating the relationship among in vitro antigiardial activity and the affinity of the molecules for DNA and their ability to inhibit the activity of giardial topoisomerase II. Each compound demonstrated antigiardial activity, as measured by assessing the incorporation of [methyl-3H]thymidine by giardial trophozoites exposed to the test agents. Three compounds exhibited excellent in vitro antigiardial activities, with 50% inhibitory concentrations which compared very favorably with those of two currently used drugs, quinacrine HCl and metronidazole. Putative mechanisms of action for these compounds were suggested by the strong correlation observed among in vitro antigiardial activity and the affinity of the molecules for natural and synthetic DNA and their ability to inhibit the relaxation activity of giardial topoisomerase II. A strong correlation between the DNA binding affinity of these compounds and their inhibition of giardial topoisomerase II activity was also observed. Giardia lamblia ; Topoisomerase ; Chemistry ; DNA ; Microbiology ; Biochemistry ; Biology Synthesis and Biological Evaluation
Authors: Cennet Yaman
Source: Kahramanmaraş Sütçü İmam Üniversitesi Tarım ve Doğa Dergisi (article, 2020-12-03)
Field: Chemistry — Analytical Chemistry

The Effect of Sample Amount and Decoction Time on The Phytochemicals and Antioxidant Activities of Decoction Lemon Balm and Sage In this study, decoctions (herbal tea) of sage (Salvia officinalis L.) and lemon balm (Melissa officinalis L), two of the important medicinal plants, were analysed for antioxidant activity, antioxidants, and minerals (K, Na, Mg, Ca, Fe, Ba, Ag and Ga) were determined in each sage and lemon balm dry leaves as well as decoctions by inductively coupled plasma-mass spectrometry (ICP-MS). The antioxidant activities of decoctions were evaluated by scavenging activities against 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and hydrogen peroxide (H2O2) radicals, and varied from 19.4 to 109.1 mg trolox equivalent (TE) cup-1 for DPPH and from 35.0 to 168.0 mg ascorbic acid equivalent (AAE) cup-1 for H2O2. The highest antioxidant activity and antioxidants such as total phenolic, flavonoid and flavanol contents were found in the decoction of lemon balm. The analysed minerals were most efficiently observed in sage decoctions. The study also showed that the best sample amount in terms of the minerals was 3 g for both species, but decoction time was statistically insignificant for sage and 10 min more effective for lemon balm. As a result, it was tried to determine the most appropriate sample amount and decoction time for the decoctions of both species according to the analysed parameters. Decoction ; Chemistry ; DPPH ; Traditional medicine ; SAGE ; Antioxidant ; Ascorbic acid ; Salvia ; Salvia officinalis ; Food science ; Officinalis ; Biochemistry ; Medicine Heavy Metals in Plants ; Phytochemicals and Antioxidant Activities ; Bee Products Chemical Analysis