jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Coralie M. Backlund
Source: Scholarworks (University of Massachusetts Amherst) (article, 2018-01-01)
Field: Materials Science — Biomaterials

Polymeric Peptide Mimics for Protein Delivery The plasma membrane is a major obstacle in the development and use of biomacromolecules for intracellular applications. Consequently, proteins with intracellular targets represent an enormous, yet under studied avenue for therapeutics. Extended research has aimed at facilitating intracellular delivery of exogenous proteins using protein transduction domains (PTDs), which allow transport of bioactive molecules into cells. Synthetic polymers, inspired by PTDs, provide a well-controlled platform to vary molecular architecture for structure activity relationship studies. Specifically, this thesis focuses on the use of ring-opening metathesis, a facile and efficient polymerization technique, through which we can vary structural parameters to optimize delivery of non-covalently encapsulated proteins. The aim was to characterize, optimize, and utilize PTD mimics (PTDMs) for functional protein delivery. Fluorescently labeled cargo were used to elucidate the predominant cellular entry mechanism for the PTDMs and were compared to their ability to deliver protein into cells. A series of polymers was designed around the most membrane active polymers to explore the incorporation of guanidine and hydrophobic moieties, yielding a PTDM capable of high protein delivery into a variety of cell types. The PTDM was then explored for use as a vaccine delivery reagent into immune cells. The ability to have a specific response with the cargo of interest verifies cytosolic delivery using the PTDMs and provides valuable insight into their use to affect intracellular pathways. Peptide ; Chemistry ; Nanotechnology ; Biochemistry ; Materials science Supramolecular Self-Assembly in Materials ; Chemical Synthesis and Analysis ; Advanced biosensing and bioanalysis techniques
Authors: Yamkela Mbandezi
Source: University of the Western Cape Electronic Theses and Dissertations Repository (University of the Western Cape) (article, 2018-01-01)
Field: Materials Science — Materials Chemistry

Evaluation of cytotoxic activity of gold nanoparticles naturally synthesised from South African indigenous medicinal plant extracts Nanotechnology has emerged as a promising field in the quest to address health conditions. Green nanotechnology is a fairly new branch of nanotechnology, which aims to produce and utilize nanomaterials in a way that is safe for living organisms and their environment. Plant extracts are increasingly used in the green synthesis of gold nanoparticles (AuNPs), which involves the reduction of sodium tetrachloroaurate (III) dehydrate by phytochemicals present in the plant extract. It is probable that the green synthesised AuNPs are more biocompatible than chemically synthesised AuNPs as biomolecules of plant origin are involved in the synthesis process. Therefore, this study aimed to explore various water extracts from indigenous South African plants, which included Perlagonium capitatum, Otholobium bracteolatum, Gerbera linnae, Morrella quercifolia, Searsia lucida, Phylica bubescens, Euclea racemosa, Tetragonia fruticosa, and Searsia glauca for their potential to synthesize AuNPs and to investigate their toxicity towards several microorganisms known to cause skin infections. These organisms play a significant role in delaying the healing of wounds. The antimicrobial properties of nanoparticles are increasing exploited in the production of wound treatments. Antimicrobial ; Nanotechnology ; Colloidal gold ; Nanomaterials ; Silver nanoparticle ; Traditional medicine ; Chemistry ; Nanoparticle ; Materials science ; Medicine ; Organic chemistry Nanoparticles: synthesis and applications
Authors: Thomas H. Allen
Source: D-Scholarship@Pitt (University of Pittsburgh) (article, 2018-09-26)
Field: Chemistry — Organic Chemistry

New Boron–Hydrogen Insertion Reactions of Ligated Boranes Chemical transformations of ligated borane complexes, including N-heterocyclic carbene boranes, are demonstrated. Chapter 1 begins with an introduction of Lewis base borane complexes, rhodium carbene chemistry, and B–H insertion of ligated boranes. The second part of Chapter 1 describes the insertion of rhodium carbenes, previously demonstrated with NHC-boranes, into the B–H bonds of other ligated boranes. Stable ligated α-boryl esters were isolated. A series of competitive B–H insertion experiments are described that were used to develop a relative reactivity profile of ligated boranes toward rhodium-catalyzed B–H insertion. The enantioselective B–H insertion of NHC-boranes with chiral dirhodium catalysts was also investigated. Finally, the synthesis and application of two chiral bridged dirhodium catalysts is described. Chapter 2 describes the discovery and isolation of NHC-boryl hydrazones by non-chain radical recombinations of NHC-boranes, diazomalonates, and azo initiators. Thermal 1,1-hydroborations of a diazo dione and a diazonium salt to give boryl hydrazone and boryl diazene products are demonstrated. Chapter 3 explores the use of electrophilic NHC-borane complexes to catalyze B–H insertion reactions with diazoesters. The boryl iodide catalyzed method is adept at producing α-substituted-α-NHC-boryl esters. A small family of NHC-boryl esters with amino acid side chains was synthesized. Chapter 4 describes the basic hydrolyses of ligated α-boryl esters to yield ligated α-boryl acetic acids. The boryl acetic acid derivatives were characterized by X-ray crystallography and acidity constant measurements. They are among the least acidic carboxylic acids known. The electron-donating ability of ligated borane substituents was further quantified by using derived Hammett constants from 13C NMR chemical shift correlation experiments. Boranes ; Chemistry ; Carbene ; Rhodium ; Borane ; Lewis acids and bases ; Insertion reaction ; Electrophile ; Alkylation ; Catalysis ; Medicinal chemistry ; Stereochemistry ; Organic chemistry ; Boron Cyclopropane Reaction Mechanisms ; Catalytic C–H Functionalization Methods ; Organoboron and organosilicon chemistry
Authors: Kotiba A. Malek
Source: Journal of Bioresource Management (article, 2018-01-01)
Field: Chemistry — Organic Chemistry

Redox-Active Silver N-Heterocyclic Carbene Complexes: A Dual Targeting Antibacterial Drug Active Silver N-heterocyclic Carbene Complexes: A Dual Targeting Anti-Bacterial Drug Bacterial resistance to current -lactam antibiotics necessitates new therapeutic approaches.Silver-based drugs offer a promising alternative because of their antibacterial properties and minimal bacterial resistance.However, many silver-based antibacterial drugs rapidly release silver ions, limiting the bioavailability of silver ions for a longer period of time.Recently, N-heterocyclic carbenes (NHC) containing silver complexes have become a popular subject of research due to their versatility and the slow release of silver ions under biological conditions.To further enhance the efficacy of silver-NHC drugs, we fused redox-active substituents such as naphthoquinone and ferrocenes to NHCs.Both naphthoquinone and ferrocenes have been shown to increase reactive oxygen species (ROS) under biological conditions that may augment the antibacterial action of redox-active silver-NHC complexes.Herein, we report synthesis and characterization of several redox-active silver-NHC complexes, 1-(ferrocenylmethyl)-3mesityl-imidazol-2-ylidene silver chloride [(2)AgCl] (compound 6), 1,3-di (ferrocenylmethyl)imidazol-2-ylidene silver chloride [(3)AgCl] (compound 7), bis (1benzyl-3-mesitylimidazol-2-ylidene) silver chloride [(1)2Ag][Cl], (compound 9), Bis (1-(ferrocenylmethyl)-3-mesityl-imidazol-2-ylidene) silver chloride [(2)2Ag][Cl] (compound 10), Bis (1,3 di(ferrocenylmethyl)imidazole-2-ylidene) silver chloride [(3)2Ag][Cl] Carbene ; Redox ; Chemistry ; Drug ; Dual (grammatical number) ; Combinatorial chemistry ; Nanotechnology ; Pharmacology ; Medicine ; Materials science ; Organic chemistry ; Catalysis ; Philosophy N-Heterocyclic Carbenes in Organic and Inorganic Chemistry ; Catalytic Cross-Coupling Reactions ; Click Chemistry and Applications
Authors: Nancy E. Hernández | William A. Hansen | Denzel Zhu | Maria E. Shea | Marium Khalid | Viacheslav Manichev | Matthew Putnins | Muyuan Chen | Anthony G. Dodge | Lu Yang | Ileana Marrero-Berríos | Melissa Banal | Phillip Rechani | Torgny Gustafsson | Leonard C. Feldman | Sang-Hyuk Lee | Lawrence P. Wackett | Wei Dai | Sagar D. Khare
Source: bioRxiv (Cold Spring Harbor Laboratory) (preprint, 2018-03-01)
Field: Materials Science — Biomaterials

Stimulus-responsive Self-Assembly of Protein-Based Fractals by Computational Design Abstract Fractal topologies, which are statistically self-similar over multiple length scales, are pervasive in nature. The recurrence of patterns at increasing length scales in fractal-shaped branched objects, e.g. , trees, lungs, and sponges, results in high effective surface areas, and provides key functional advantages, e.g. , for molecular trapping and exchange. Mimicking these topologies in designed protein-based assemblies will provide access to novel classes of functional biomaterials for wide ranging applications. Here we describe a computational design approach for the reversible self-assembly of proteins into tunable supramolecular fractal-like topologies in response to phosphorylation. Computationally-guided atomic-resolution modeling of fusions of symmetric, oligomeric proteins with Src homology 2 (SH2) binding domain and its phosphorylatable ligand peptide was used to design iterative branching leading to assembly formation by two enzymes of the atrazine degradation pathway. Structural characterization using various microscopy techniques and Cryo-electron tomography revealed a variety of dendritic, hyperbranched, and sponge-like topologies which are self-similar over three decades (~10nm-10μm) of length scale, in agreement with models from multi-scale computational simulations. Control over assembly topology and formation dynamics is demonstrated. Owing to their sponge-like structure on the nanoscale, fractal assemblies are capable of efficient and phosphorylation-dependent reversible macromolecular capture. The described design framework should enable the construction of a variety of novel, spatiotemporally responsive biomaterials featuring fractal topologies. One Sentence Summary We report a computationally-guided bottom up design approach for constructing fractal-shaped protein assemblies for efficient molecular capture. Network topology ; Fractal ; Topology (electrical circuits) ; Supramolecular chemistry ; Branching (polymer chemistry) ; Protein design ; Computational model Supramolecular Self-Assembly in Materials ; Bacteriophages and microbial interactions ; Diatoms and Algae Research
Authors: Alexander J. Stirk
Source: Scholarship at UWindsor (University of Windsor) (article, 2018-01-01)
Field: Chemistry — Inorganic Chemistry

Reticular Synthesis of Metal-Organic Rotaxane Frameworks The work herein, describes the placement of mechanically interlocked molecules (MIMs) into ordered, crystalline metal-organic frameworks (MOFs) to create metal-organic rotaxane frameworks (MORFs). This placement is done through the use of the concepts of reticular synthesis, to create predictable materials based on prior known building blocks and topological nets in order to achieve robust dynamics. The concepts of MIMs, nets, reticular synthesis, robust dynamics are all discussed in detail in Chapter 1. Also outlined in Chapter 1 are six design criteria that act as a blueprint for the creation of robust dynamics using the tenants of reticular synthesis. Chapter 2 shows the targeting of nbo derived topological nets for incorporating a T-shaped [2]rotaxane linker. The targeting of this net produced three MOFs of UWCM-CH3 and the two phases of α/β-UWDM-CF3 (University of Windsor Crystalline Material). Topological analysis of the nets show that the nbo derived fof net was produced by UWCM-CH3 and α-UWCM-CF3. Also reported is the first instance of the newly named loz net of β-UWCM-CF3. Chapter 3 is an evolution of the T-shaped linker design for the targeting of lvt nets. This endeavour resulted in the isoreticular lil nets of UWCM-10 and the MIM containing UWDM-10 (University of Windsor Dynamic Material). Through the use of variable temperature 2H solid-state nuclear magnetic resonance spectroscopy (SSNMR), the rotational motion of the mechanically bound wheel of the [2]rotaxane was characterised. Chapter 4 uses a linear T-shaped linker design to target the edge-transitive pcu net resulting in the isoreticular MOF and MORFs, UWCM-11 and UWDM-11. The rotational dynamics of UWDM-11 were probed using VT 2H SSNMR. Chapter 5 uses the same linear T-shaped [2]rotaxane linker for incorporation into the edge-transitive net of fcu producing UWDM-12. The Zr MOF was targeted for the high chemical stability of the secondary building unit (SBU) allowing for acid/base chemistry on the benzimidazole/benzimidazolium axle of the [2]rotaxane. This produced both UWDM-12[Neutral] and UWDM-12[Protonated] that were shown through VT 2H SSNMR to have a qualitative effect on the rotational dynamics of the mechanically bound wheel inside the framework – a first for the UWDM series. Chapter 6 evaluates the six design objectives, and debates their practicality in the pursuit of creating robust dynamics by using reticular synthesis. Rotaxane ; Chemistry ; Crystallography ; Supramolecular chemistry ; Crystal structure Metal-Organic Frameworks: Synthesis and Applications ; Supramolecular Chemistry and Complexes ; Silicone and Siloxane Chemistry
Authors: M. Akbari | S. Ramakrishna | Sophie Laurent | M.-S. Shokrgozar | A. Davoud | D. Mohammad | S. Bonakdar | S. Mohammadi
Source: ORBi UMONS (article, 2018-01-01)
Field: Materials Science — Biomaterials

Fabrication of Nanofibrous PVA/Alginate-Sulfate Substrates for Growth Factor Delivery peer reviewed Fabrication ; Nanofiber ; Process (computing) ; Extrusion ; Substrate (aquarium) Electrospun Nanofibers in Biomedical Applications ; Bone Tissue Engineering Materials ; Graphene and Nanomaterials Applications
Authors: Rachael L. Smith | Martin Vickers | Christoph G. Salzmann
Source: ChemRxiv (preprint, 2018-11-23)
Field: Materials Science — Materials Chemistry

Stacking Disorder by Design: Factors Governing the Polytypism of Silver Iodide upon Precipitation and Formation from the Superionic Phase Silver iodide (AgI) is used for a wide range of applications from photocatalysis and antimicrobial coatings to photography and ice nucleation. By fitting powder X-ray diffraction patterns with DIFFaX, we show that AgI displays a strong tendency to form stacking-disordered materials. Its polytypism is determined by the silver cation to iodide molar ratio during precipitation. Under iodide-rich conditions, fully hexagonal &lt;i&gt;b&lt;/i&gt;-AgI is obtained whereas a maximal percentage of cubic stacking of 80% is obtained at a 1:2 molar ratio in the silver cation-rich regime. These findings are explained on the basis of a concentration-dependent competition between kinetically and thermodynamically-favored adsorption processes. Furthermore, the previously reported memory effects observed upon transforming hexagonal and cubic AgI to the high-temperature superionic phase and back are now followed quantitatively. We propose that the memory effects originate from excess ions at the surfaces of AgI crystals that stabilize the pyroelectricity of AgI associated with hexagonal stacking. The ability to ‘design’ the polytypism of AgI by tuning the precipitation conditions provides a first example where the stacking disorder of a material can be controlled in a continuous fashion. Future studies will clarify if this design principle can be applied to other materials as well. Stacking ; Silver iodide ; Materials science ; Precipitation ; Nucleation ; Iodide ; Hexagonal crystal system ; Phase (matter) ; Crystallography ; Molar ratio ; Hexagonal phase ; Chemical engineering ; Inorganic chemistry ; Nanotechnology ; Chemistry ; Layer (electronics) ; Organic chemistry Copper-based nanomaterials and applications ; Quantum Dots Synthesis And Properties ; Advanced Condensed Matter Physics
Authors: L. Ehrenberg | Filip Nilsson
Source: Lund University Publications Student Papers (Lund University) (article, 2018-01-01)
Field: Materials Science — Biomaterials

Analysing and concluding the cost/performance matrix for biopolymer blends with different renewable contents Due to increasing awareness and consumer demands it has become important for companies to develop an economical and environmentally sustainable alternative to traditional petroleum-based plastics. The transition from fossil material to bio based is important for the future of people and planet, still, how the transformation should be implemented is yet unknown. In this report, the possibilities of developing a polymer blend between PP and the biopolymers PLA, PBS and PHA are investigated for commercial application in IKEA plastic products. The value chain, from feedstock to polymer is covered to give the reader a holistic understanding of the challenges and opportunities for biopolymer blends in plastic applications. Cost is introduced as a crucial parameter to increase the relevancy of the material from a commercial point of view, in addition to technical aspects. The mechanical and thermal properties of the bio/fossil blends is examined in a joint venture between IKEA and Fraunhofer ICT. The report also covers a deeper explanation of PHA materials and a cost/capacity evaluation for this polymer. After the material properties of the blend material is examined, an extensive discussion about the application and recyclability follows. Blends between PP and PHA modified with additives were made and tested in relation to IKEA specifications as cost was considered. The blends show promising properties but should be further optimized to be implemented in IKEA products. Raw material ; Biopolymer ; Fossil fuel ; Plastic packaging ; Biochemical engineering ; Materials science ; Process engineering ; Polymer science ; Polymer ; Pulp and paper industry ; Waste management ; Composite material ; Engineering ; Chemistry biodegradable polymer synthesis and properties ; Additive Manufacturing and 3D Printing Technologies ; Polymer crystallization and properties
Authors: Chad Priest
Source: eScholarship (California Digital Library) (article, 2018-01-01)
Field: Chemistry — Inorganic Chemistry

Theoretical Insight Towards Uranium Extraction from Seawater Uraniumâs economical consumption is based on the industrial nuclear fuel cycle. Today there remains 4-6 million tons of terrestrial uranium in Earthâs ores. However, as the projected population is estimated to double by 2040, current uranium reserves are only estimated to provide nuclear fuel for the next century. Unconventional methods for acquiring uranium are, therefore, required to maintain longevity and sustainability for future economic nuclear energy demands. One unconventional alternative for mining uranium is diving from land and into the open seas. Although uranium resides uniformly in the oceans at very low concentrations of 3.3 ppb, in a vast body of Earths water, there exists an untapped reserve of uranium at an astounding 4.5 billion ton. Uranium exists in aqueous environment as the stable oxo-cation, in the hexavalent (VI) state called uranyl, UO22+, and as the neutral ternary-uranyl-carbonato, Ca2UO2(CO3)3, in seawater. After six generations of research and development, current extraction methods rely on a polymer grafter amidoxime-based (poly(AO)) material for uranium recovery from seawater. One chemical advancement in adsorption capacity is from the inclusion the hydrophilic group carboxylate (Ac). However, displacing coordinating carbonates with poly(amidoxime) from uranyl, which is both at low concentrations and existing in soup of various metal-ions in a seawater matrix, still remains a formidable challenge. One of the multifaceted efforts involved with increasing adsorption selectivity is by the theoretical insight into uraniumâs coordination chemistry with interacting ligands in seawater-related environments.Herein we utilize current state-of-the-art, advanced computing technology to investigate coordinating uranium species in a completely explicit model. First, we employ a pure quantum mechanical (QM) simulations to pry into the chemistry of surrounding water moleculesâ influence on the dominant Ca2[UO2(CO3)3] specie. Furthermore, large scale classical molecular dynamics (CMD) simulations are assisted with umbrella sampling to develop computational techniques for investigating coordinating uranyl-AO from calculating binding free-energies (ïGbind). Furthermore, we investigate the influence of capacity by inspecting the interactions of mix-ligand containing AO/Ac. Additionally, employing umbrella sampling method coupled with WHAM, we investigate the sodium ion solvation environment of one of the most competing vanadium-containing species, HVO42-. Uranium ; Uranyl ; Seawater ; Chemistry ; Population ; Uranium ore ; Adsorption ; Nuclear fuel ; Environmental science ; Nuclear chemistry ; Geology ; Metallurgy ; Materials science ; Oceanography Radioactive element chemistry and processing ; Radioactive contamination and transfer ; Chemical Synthesis and Characterization
Authors: 磐仪 梁
Source: Hokkaido University Collection of Scholarly and Academic Papers (Hokkaido University) (article, 2018-09-25)
Field: Materials Science — Materials Chemistry

Development of Thermal Process Methodology and Mechanochemical Synthesis for Luminescent Copper(I)-halide Complexes Halide ; Copper ; Process (computing) ; Luminescence ; Chemistry ; Thermal ; Process engineering ; Materials science ; Computer science ; Inorganic chemistry ; Organic chemistry ; Engineering ; Physics ; Thermodynamics ; Optoelectronics Luminescence Properties of Advanced Materials ; Pigment Synthesis and Properties ; Thermal and Kinetic Analysis
Authors: Vidya Zende | Tejpalsingh Ramsingh Girase | Nicolas Chrysochos | Anant R. Kapdi | Carola Schulzke
Source: Acta Crystallographica Section E Crystallographic Communications (article, 2018-10-26)
Field: Chemistry — Organic Chemistry

Crystal structure of 1-butyl-3-{2-[(indan-5-yl)amino]-2-oxoethyl}-1<i>H</i>-imidazol-3-ium chloride In the cation of the title mol-ecular salt, C<sub>18</sub>H<sub>24</sub>N<sub>3</sub>O<sup>+</sup>·Cl<sup>-</sup>, an intra-molecular C-H⋯O hydrogen bond stabilizes the almost coplanar orientation of the aromatic ring of the indane unit and the amide plane. In the crystal, the packing is dominated by inter-molecular C-H⋯Cl hydrogen-bonding inter-actions that result in the formation of slab-like structures propagating along [010]. The slabs are linked by weak C-H⋯O inter-actions, forming layers lying parallel to (100). The methyl-ene carbon atom of the indanyl substituent is disordered over two positions with a refined occupancy ratio of 0.84 (2):0.16 (2). The crystal studied was refined as a twin with matrix [1 0 0.9, 0 0, 0 0 ]; the resulting BASF value is 0.30. Hydrogen bond ; Crystallography ; Intramolecular force ; Chemistry ; Ring (chemistry) ; Crystal (programming language) ; Intermolecular force ; Substituent ; Methylene ; Amide ; Crystal structure ; Aromaticity ; Stereochemistry ; Medicinal chemistry ; Molecule ; Organic chemistry Synthesis and Reactions of Organic Compounds ; N-Heterocyclic Carbenes in Organic and Inorganic Chemistry ; Synthesis of heterocyclic compounds
Authors: 光磊 李
Source: Hokkaido University Collection of Scholarly and Academic Papers (Hokkaido University) (article, 2018-12-25)
Field: Materials Science — Materials Chemistry

Suzuki–Miyaura cross-coupling based synthesis and characterization of fluorescent and chemiluminescent boron dipyrromethene dyes spanning near-infrared region Fluorescence ; Boron ; Chemistry ; Photochemistry ; Characterization (materials science) ; Nanotechnology ; Materials science ; Physics ; Optics ; Organic chemistry Luminescence and Fluorescent Materials ; Carbon and Quantum Dots Applications ; Conducting polymers and applications