jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Manohar Singh | Vasantha Kumar Rajendran | J. C. Pandey
Source: Computational Materials Science (article, 2020-07-09)
Field: Materials Science — Materials Chemistry

A novel bisection method based algorithm to quantify interphase in epoxy alumina nanocomposites Interphase ; Materials science ; Permittivity ; Composite material ; Epoxy ; Nanocomposite ; Polymer nanocomposite ; Polymer ; Dielectric High voltage insulation and dielectric phenomena ; Dielectric materials and actuators ; Polymer Nanocomposites and Properties
Authors: Chengyang Jiang | Parastoo Sakinejad | Ruoyu Xu | Yongchun Tang
Source: Colloid & Polymer Science (article, 2020-06-19)
Field: Chemistry — Organic Chemistry

Modulation of rheological behaviors of hydrophobically modified polyacrylamide based on micellar kinetics Kinetics ; Polyacrylamide ; Pulmonary surfactant ; Rheology ; Micelle ; Chemical engineering ; Polymer ; Chemistry ; Shear rate ; Aqueous solution ; Dilatant ; Thixotropy ; Polymer chemistry ; Organic chemistry ; Materials science ; Composite material Surfactants and Colloidal Systems ; Enhanced Oil Recovery Techniques ; Rheology and Fluid Dynamics Studies
Authors: Yulia D. Gordievskaya | Elena Yu. Kramarenko
Source: Soft Matter (article, 2020-12-08)
Field: Materials Science — Materials Chemistry

Conformational transitions and helical structures of a dipolar chain in external electric fields The conformational behavior of a single dipolar chain in a uniform electric field is investigated by molecular dynamics simulations. The dipolar chain is modeled as a backbone bead-on-spring chain of equally charged beads, each connected by a rigid spring with an oppositely charged side bead that can freely rotate around the backbone bead. In the strong coupling regime, when the dipolar chain is in the globular state due to a strong electrostatic correlational attraction, the application of an electric field causes the chain swelling and elongation along the field direction. In the weak coupling regime, a qualitatively new regime is found when the swollen dipolar chain shrinks along the field direction adopting flattened conformations due to the field-induced anisotropy of the chain rigidity and the head-to-tail attraction of the dipoles orienting along the field lines. A novel helical conformation is detected for low-polar media and strong electric fields. An increasing rigidity of the backbone chain leads to some stabilization of the helical conformation and the formation of double and triple helices as well as flat spread springs. Fine tuning of the interplay between dipolar and volume interactions by external electric fields induces re-orientation of rod-like dipolar chains in dilute solutions. The obtained results can provide new ways to control dipolar polymer conformations and design materials with responsive properties. Electric field ; Dipole ; Chain (unit) ; Molecular dynamics ; Chemical physics ; Materials science ; Condensed matter physics ; Chemistry ; Physics ; Computational chemistry Material Dynamics and Properties ; Surfactants and Colloidal Systems ; Characterization and Applications of Magnetic Nanoparticles
Authors: Jia-Chuan Lin | Yu‐Chen Huang
Source: Optics Express (article, 2020-09-09)
Field: Materials Science — Materials Chemistry

Three-dimensional electrochemical etching by grid ditching for multi-wavelength visible-light emission on porous silicon A new approach of three-dimensional electro-chemical etchings both in vertical and lateral current directions on grid ditched Si pn-structures is originally proposed. Lateral etchings on the different ditched zones cause different porosities on porous Si, which emit visible lights of different wavelengths under ultraviolet light stimulation. Therefore, a single Si-based chip is capable of emitting visible light with tunable and multiple wavelengths simultaneously by this new approach. Moreover, the etching conditions on porous Si films and their related wavelengths can be fine-tuned by area sizes. Compared with the conventional method, the new approach provides a new option for multi-wavelength chip design with a precise patterning for porous Si without any mask and photoresist. Materials science ; Porous silicon ; Wavelength ; Photoresist ; Visible spectrum ; Etching (microfabrication) ; Optics ; Optoelectronics ; Silicon ; Ultraviolet ; Porosity ; Photolithography ; Nanotechnology ; Layer (electronics) ; Composite material Silicon Nanostructures and Photoluminescence ; Nanowire Synthesis and Applications ; Semiconductor materials and devices
Authors: Óscar Castillo | Esther Delgado | Elisa Hernández | María Pérez | Félix Zamora
Source: Crystal Growth & Design (article, 2020-05-12)
Field: Materials Science — Electronic, Optical and Magnetic Materials

Structural Factors Governing the Formation of Extended Structures in Group 10 and 12 Metal-Dithiolenes A series of metal-dithiolene compounds have been prepared by direct reactions between MCl2·6H2O (M = Ni, Zn) or HgCl2 with HSC6H2X2SH (X = Cl or H) in the presence of a base. The fine-tuning of the reaction conditions has allowed us to rationalize part of the structural factors governing the formation of coordination polymers versus discrete metal-dithiolene complexes. With the aim to gain knowledge of the formation of extended metal–organic structures, we have also studied the reaction between Na[Ni(SC6H2Cl2S)2] and HgCl2. These reactions lead to the formation of either discrete compounds or extended structures. The detailed structural analysis of 11 compounds has allowed us to uncover some relevant clues about the formation of coordination polymers based on dithiolenes. We have observed that extended structures are typically formed when: (i) the sulfur atoms apart from being involved in the chelation of the transition metal center also coordinate to the alkaline metal center; i.e., dithiolene acts as a bridging ligand; (ii) water molecules preferentially coordinate to alkaline centers mostly acting as bridging molecules; and (iii) bulkier alkaline cations are employed to allow a greater number of sulfur atoms coming from the metal-dithiolene entities to be incorporated in their coordination sphere. The results obtained ensure that a combination of at least two of these features gives rise to polymeric coordination entities. Chemistry ; Metal ; Molecule ; Coordination sphere ; Ligand (biochemistry) ; Transition metal ; Crystallography ; Coordination complex ; Bridging ligand ; Chelation ; Polymer ; Coordination polymer ; Crystal structure ; Inorganic chemistry ; Organic chemistry ; Catalysis Organic and Molecular Conductors Research ; Inorganic Fluorides and Related Compounds ; Perovskite Materials and Applications
Authors: Bingnan Qian | Fan Sun | P. Vermaut | F. Prima
Source: MATEC Web of Conferences (article, 2020-01-01)
Field: Materials Science — Materials Chemistry

Fine-tuning of stress-induced martensite in TRIP/TWIP Ti alloys Fine-tuning of stress-induced martensitic (SIM) transformation was studied in Ti-Mo based β metastable alloys, showing combined Transformation Induced Plasticity (TRIP) and Twinning Induced Plasticity effects (TWIP) effects. The work aimed to clarify the transition and interaction between the two deformation mechanisms and their influences on the mechanical properties of Ti-Mo based alloys. Electron parameter design methods (Bo-Md and e/a ratio) were cross-used to increase the β phase stability from near-TRIP to near-TWIP by adding third alloying elements. SIM α″ transformation and mechanical twinning were traced by in-situ EBSD (Electron backscatter diffraction) mapping under cyclic tension. The deformation modes of β phase exhibited significant changes when shifting its metastability via chemical composition modifications. In near-TRIP conditions (dominated by the growth of SIM α″ in plastic regime), SIM α″ transformation and internal twinning of martensite were the main mechanisms to accommodate the local stress-strain conditions. In near-TWIP ones (dominated by the growth of {332}&lt;113&gt;β twinning in plastic regime), SIM α″ was observed only at twinning interface during strain process and disappeared after stress release. Twip ; Crystal twinning ; Materials science ; Plasticity ; Electron backscatter diffraction ; Martensite ; Deformation (meteorology) ; Diffusionless transformation ; Stress (linguistics) ; Metallurgy ; Phase (matter) ; Condensed matter physics ; Composite material ; Microstructure ; Chemistry ; Physics Titanium Alloys Microstructure and Properties ; Intermetallics and Advanced Alloy Properties ; Advanced materials and composites
Authors: Emma Incocciati | Roberto Lauri | Biancamaria Pietrangeli
Source: Zenodo (CERN European Organization for Nuclear Research) (article, 2020-04-01)
Field: Materials Science — Biomaterials

Innovative Mixed Microbial Culture Processes for Pha Production at Pilot Scale: Professional Chemical Risk Assessment Identification and fine-tuning of a process that allows the effective conversion of organic carbon from urban waste into valuable bio-based products is the main goal of “REsources from URban BIowaSte”- RES URBIS (GA 7303499) project in the European Horizon2020 program.\n\nIn this frame, the Mixed Microbial Culture (MMC) process for polyhydroxyalkanoates (PHA) production has notbeen exploited at full scale yet and the process is presently under investigation only at pilot scale.\n\nThe successful development and the industrial implementation of a safe biochemical conversion process is essential for meeting sustainable development goals. Although the health and safety risks posed by bioprocesses for the valorisation of biomass are usually expected to be lower than the traditional chemical and petrochemical processes, there is still a lack of information about these aspects of biorefinery plants, especially for novel bioprocesses under development.\n\nTaking steps to meet this challenge, the work presents early results of professional chemical risk assessment in application to the MMC-PHA production process at pilot plant scale. The assessment has been performed applying a guideline drawn up by Italian National System for Environmental Protection for the protection of operators from risks to their safety and health arising, or likely to arise, from the effects of chemical agents that are present at the workplace or as a result of any work activity involving chemical agents. Meeting the requirements of Community legislation and the updates introduced by EC Regulation 1907/2006 (REACH, 2006) and EC Regulation 1272/2008 (CLP, 2008), the guideline provides a methodology for chemical risk assessment distinguishing between risks for safety, related to reactivity and chemical-physical properties of chemicals, and risks for health, mainly ascribable to toxicological properties of chemical agents.\n\nStarting from the analysis of the Process Flow Diagram of a pilot scale plant for PHA production, a lot of information (hazardous properties of chemical agents, circumstances of work involving such agents, including their amount, level, type and duration of exposure, relevant material safety data sheets, occupational exposure limit values, effect of preventive measures taken or to be taken) has been collected in order to apply the guideline criteria and the joined IT tool. The paper presents the results of the assessment attempt. Production (economics) ; Scale (ratio) ; Environmental science ; Biochemical engineering ; Business ; Engineering ; Geography ; Economics biodegradable polymer synthesis and properties ; Chemistry and Chemical Engineering ; Sustainable Supply Chain Management
Authors: Claudiu Locovei | Nicolae Filipoiu | Andrei Kuncser | Anda Elena Stanciu | S. Antohe | Camelia Florica | Andreea Costas | Ionuţ Enculescu | Luc Piraux | V. Kuncser | Vlad‐Andrei Antohe
Source: Nanomaterials (article, 2020-12-07)
Field: Materials Science — Materials Chemistry

Unidirectional Magnetic Anisotropy in Dense Vertically-Standing Arrays of Passivated Nickel Nanotubes We report the facile and low-cost preparation as well as detailed characterization of dense arrays of passivated ferromagnetic nickel (Ni) nanotubes (NTs) vertically-supported onto solid Au-coated Si substrates. The proposed fabrication method relies on electrochemical synthesis within the nanopores of a supported anodic aluminum oxide (AAO) template and allows for fine tuning of the NTs ferromagnetic walls just by changing the cathodic reduction potential during the nanostructures' electrochemical growth. Subsequently, the experimental platform allowed further passivation of the Ni NTs with the formation of ultra-thin antiferromagnetic layers of nickel oxide (NiO). Using adequately adapted magnetic measurements, we afterwards demonstrated that the thickness of the NT walls and of the thin antiferromagneticNiO layer, strongly influences the magnetic behavior of the dense array of exchange-coupled Ni/NiO NTs. The specific magnetic properties of these hybrid ferromagnetic/antiferromagnetic nanosystems were then correlated with the morpho-structural and geometrical parameters of the NTs, as well as ultimately strengthened by additionally-implemented micromagnetic simulations. The effect of the unidirectional anisotropy strongly amplified by the cylindrical geometry of the ferromagnetic/antiferromagnetic interfaces has been investigated with the magnetic field applied both parallel and perpendicular to the NTs axis. Materials science ; Ferromagnetism ; Antiferromagnetism ; Non-blocking I/O ; Passivation ; Nickel ; Magnetic anisotropy ; Anisotropy ; Nickel oxide ; Nanotechnology ; Thin film ; Oxide ; Exchange bias ; Fabrication ; Optoelectronics ; Condensed matter physics ; Magnetic field ; Layer (electronics) ; Magnetization ; Metallurgy ; Optics ; Chemistry Anodic Oxide Films and Nanostructures ; Magnetic properties of thin films ; Nanoporous metals and alloys
Authors: Sơn Tùng Ngô | Han N. Phan | Chinh N. Le | Nhung Cam Thi Ngo | Khanh B. Vu | Nguyễn Thanh Tùng | Cuong X. Luu | Van V. Vu
Source: The Journal of Physical Chemistry B (article, 2020-01-28)
Field: Chemistry — Inorganic Chemistry

Fine Tuning of the Copper Active Site in Polysaccharide Monooxygenases Type 2 copper active sites, one of the several important copper active sites in biology, were recently found in the novel superfamily of polysaccharide monooxygenases (PMOs) that cleave recalcitrant polysaccharides via an unprecedented oxidative mechanism. The copper center in PMOs is ligated by the bidentate N-terminal histidine residue and another conserved histidine residue, forming a unique T-shaped core termed as <i>Histidine brace</i>. This core serves as the foundation for diverse structures and electronic properties among PMO families and subfamilies. Understanding of the copper active site in PMOs is limited to the static solid structures obtained with X-ray diffraction (XRD), whereas in several families, the copper center exists as a mixture of species in solution as indicated by electron paramagnetic resonance (EPR) spectroscopy. To obtain further details on the copper active sites in PMOs, we carried out density functional theory calculations and molecular dynamics simulations on <i>Mt</i>PMO3* that were previously studied with XRD, EPR, mutagenesis, and activity assays. The results reveal the fine-tuning of the binding of the distal ligands by both proximal and distal H-bond-forming residues. Q167 forms H bonds with the proximal O<sub>Tyr</sub> ligand of Y167 and the equatorial aqueous ligand (O<sub>eq</sub>). T74 forms a H bond with the distal aqueous ligand (O<sub>dis</sub>). Removing these H bonds by mutating Q167 or T74 to alanine results in great fluctuations of the axial ligands. Strengthening the proximal H bonds by mutating Q167 to glutamate confines Y167 to the copper centers. In all mutants, the residence time of O<sub>dis</sub> is significantly reduced. Q167A, Q167E, and T74A mutants were previously shown to have a significantly reduced activity. Our results indicate that well-tuned H bonds are required for the activity of PMOs. Active site ; Copper ; Chemistry ; Crystallography ; Electron paramagnetic resonance ; Ligand (biochemistry) ; Stereochemistry ; Nuclear magnetic resonance ; Organic chemistry ; Biochemistry ; Catalysis Metal-Catalyzed Oxygenation Mechanisms ; Metal complexes synthesis and properties ; Enzyme Structure and Function
Authors: Neskarlys Rios | Franmerly Fuentes | Juan Manuel Garcia Garfido | Yomaira Otero
Source: ChemRxiv (preprint, 2020-07-14)
Field: Chemistry — Inorganic Chemistry

Synthesis, Characterization and Photophysical Properties of a New 2,5-Di(aryl)phosphole Derivative and Their Trigonal Copper-Phosphole Complexes &lt;div&gt;A new phosphole derivative 2,5-di(2-quinolyl)-1-phenylphosphole (&lt;b&gt;1&lt;/b&gt;) was synthesized by using the Fagan-Nugent method. Phosphole was obtained as an air stable solid in high yield (73%). Additionally, two new copper phosphole complexes [CuX(Phosphole)&lt;sub&gt;2&lt;/sub&gt;] (X = Cl (&lt;b&gt;2a&lt;/b&gt;), I (&lt;b&gt;2b&lt;/b&gt;), Phosphole = &lt;b&gt;1&lt;/b&gt;) have been synthesized by reaction of CuX (X = Cl, I) and phosphole derivative (&lt;b&gt;1&lt;/b&gt;). All compound were characterized by NMR, ESI-MS, UV–Vis and fluorescence spectroscopy. The photophysical properties of all compounds were analyzed, UV-Vis spectra of the complexes &lt;b&gt;2a-b&lt;/b&gt; shown π–π* transitions with shift very similar to the found in the free phosphole due to that their symmetrical structures inhibits efficient ILCT. We have found that the compounds &lt;b&gt;1&lt;/b&gt;, &lt;b&gt;2a-b&lt;/b&gt; exhibited fluorescence between 460 and 583 nm with quantum yields of Φ&lt;sub&gt;f&lt;/sub&gt; = 0.04 – 0.11. The emission energy of &lt;b&gt;2b&lt;/b&gt; is higher than &lt;b&gt;2a&lt;/b&gt;, suggesting that λ&lt;sub&gt;max&lt;/sub&gt; is affected by the ligand-field strength of the halogen ions in the complexes (I&lt;sup&gt;-&lt;/sup&gt; &lt; Cl&lt;sup&gt;-&lt;/sup&gt; ).&lt;/div&gt; Phosphole ; Chemistry ; Derivative (finance) ; Ligand (biochemistry) ; Stereochemistry ; Medicinal chemistry ; Receptor Synthesis and characterization of novel inorganic/organometallic compounds ; Organophosphorus compounds synthesis ; Fungal Plant Pathogen Control
Authors: Neeta Singh | Priyanka Yadav | S. K. Gupta
Source: RASAYAN Journal of Chemistry (article, 2020-01-01)
Field: Materials Science — General Materials Science

STRATEGIES AND CHARACTERIZATION METHODS IN THE PREPARATION OF POLYMERIC SURFACTANTS FOR VARIOUS APPLICATIONS The polymeric surfactants are gaining the attention of researchers and scientists because of their enhanced surfaceactive properties. In this review, an effort is made to highlight the application of polymeric surfactants and discuss the methods used for their synthesis from different types of feedstocks. The physicochemical properties of polymeric surfactants are superior to conventional surfactants with excellent surface-active features. The development of analytical methods for the characterization of polymers with complex macromolecular structural architectures is essential for the synthesis of polymeric surfactants. Emphasis is laid upon the discussion on the intermolecular micellar aggregates formed as a result of interactions between the polymer backbone and the amphiphilic micelles along with the impact of controlled polymerization to enhance the features of the polymeric surfactants in the detergent industry. An effort to comprehensively analyze the methods deployed for the synthesis of polymeric surfactants concerning their characteristic features that are unique to polymeric surfactants which enable them to be extensively used in the detergent industry is done. These discussions will help in understanding and designing polymeric surfactants for specific applications in the detergent industry. Characterization (materials science) ; Materials science ; Nanotechnology Material Properties and Applications
Authors: Balakrishna Kalluraya | Babiya Kaushik | H.M. Somashekarappa
Source: Journal of Modern Materials (article, 2020-07-05)
Field: Materials Science — Polymers and Plastics

Effect of Gamma- Irradiation on Structure, Morphology and Thermal Properties of Novel Polyamide Based Thermoset Obtained by Double Cycloaddition Cycloaddition reactions gained prominence in macromolecular chemistry for generating macromolecules because of high yields of these reactions, which is a key tool that drives polyaddition reactions. Cycloaddition reaction plays major role in extension of polymerisation or in other words high conversions of monomers to macromolecules of high molecular weights. Until the late 1990s, the major studies regarding cycloadditions in novel polymer synthesis were related to polyaddition reactions. Since then in the field of polymer synthesis the affirmative strengths of these cycloaddition reactions have been exhibited in multi fold polymer design and headway material architecture. Future demand exists in unlatching the capacity of these novel synthetic routes for advanced applications in catalysis, separation, optoelectronics, and analytical media. Thus, we have developed an able and productive synthetic podium for the preparation of a new class of polyimide based on the double 1, 3-dipolar cycloaddition of thiasydnone with bis-maleimide. This paper reports the effect of gamma irradiation on the changes in physico-chemical properties of the polyamide based thermoset synthesised by double cycloaddition approach. The thermoset synthesized by this exclusive approach were irradiated with gamma doses in the range 10- 300 kGy. The substantial effect of gamma radiation and the structural modifications induced on the thermoset have been studied as a function of dose using different characterization techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry- thermo gravimetric analysis (DSC-TGA), Field Emission Scanning Electron Microscope (FESEM) and UV-Vis Spectroscopy. Cycloaddition ; Thermosetting polymer ; Materials science ; Differential scanning calorimetry ; Polymer ; Polymer chemistry ; Macromolecule ; Maleimide ; Polyamide ; Fourier transform infrared spectroscopy ; Chemical engineering ; Chemistry ; Organic chemistry ; Composite material ; Catalysis Synthesis and properties of polymers ; Photopolymerization techniques and applications ; Polymer Nanocomposite Synthesis and Irradiation
Authors: Eugenia Kumacheva | R. M. Choueiri | M. Rubinstein | Anna Klinkova | H. Therien-Aubin
Source: UNC Libraries (article, 2020-11-08)
Field: Chemistry — Physical and Theoretical Chemistry

Colloidal analogs of molecular chain stoppers Self-assembly of nanoparticles in polymer-like chains bears a strong similarity to polymerization reactions, in which monomer units are brought together by directional noncovalent interactions. Based on this similarity, the molecular concepts of polymer chemistry can be applied to achieve controllable nanoparticle assembly. On the other hand, the ability to visualize nanoparticle assemblies and to exploit characterization tools used in nanoscience offers a unique way to study polymerization reactions. Here we explore this twofold strategy for an exemplary system including the self-assembly of bifunctional metal nanorods in the presence of monofunctional nanoparticles (chain stoppers). The approach provided insight into the polymerization kinetics, side reactions, the distribution of species in the system, and the design rules for the synthesis of molecular chain stoppers. Chain (unit) ; Colloid ; Chemistry ; Polymer science ; Nanotechnology ; Materials science ; Physics ; Organic chemistry Various Chemistry Research Topics