jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Aleksandra Benko
Source: Cancer Drug Resistance (review, 2020-01-01)
Field: Materials Science — Materials Chemistry

Nanocarrier drug resistant tumor interactions: novel approaches to fight drug resistance in cancer Cancer is one of the biggest healthcare concerns in our century, a disease whose treatment has become even more difficult following reports of drug-resistant tumors. When this happens, chemotherapy treatments fail or decrease in efficiency, leading to catastrophic consequences to the patient. This discovery, along with the fact that drug resistance limits the efficacy of current treatments, has led to a new wave of discovery for new methods of treatment. The use of nanomedicine has been widely studied in current years as a way to effectively fight drug resistance in cancer. Research in the area of cancer nanotechnology over the past decades has led to tremendous advancement in the synthesis of tailored nanoparticles with targeting ligands that can successfully attach to chemotherapy-resistant cancer by preferentially accumulating within the tumor region through means of active and passive targeting. Consequently, these approaches can reduce the off-target accumulation of their payload and lead to reduced cytotoxicity and better targeting. This review explores some categories of nanocarriers that have been used in the treatment of drug-resistant cancers, including polymeric, viral, lipid-based, metal-based, carbon-based, and magnetic nanocarriers, opening the door for an exciting field of discovery that holds tremendous promise in the treatment of these tumors. Drug ; Drug resistance ; Nanocarriers ; Cancer drugs ; Cancer ; Pharmacology ; Medicine ; Biology ; Internal medicine ; Genetics Advanced Nanomaterials in Catalysis ; Nanoplatforms for cancer theranostics ; Advanced biosensing and bioanalysis techniques
Authors: Martin Pelzer | Thomas Vad | Amrei Becker | Thomas Gries | Svetlana Markova | V. V. Teplyakov
Source: Journal of Applied Polymer Science (article, 2020-07-06)
Field: Materials Science — Polymers and Plastics

Melt spinning and characterization of hollow fibers from poly(4‐methyl‐1‐pentene) Abstract In this article, the melt spinning behavior of poly(4‐methyl‐1‐pentene) (PMP) hollow fibers (HF) is examined. The melt spinning trials are carried out on a pilot scale melt spinning plant with different settings while a 10‐hole 2c‐shaped spinneret is used. It is found that the winding speed mainly affects the outer fiber diameter. The influence of different melt spinning parameters is investigated, in particular temperatures, take‐up velocities, and the use of quench air. For this purpose, the shape and crystalline structure of the fibers are analyzed using a light microscope, a scanning electron microscope, and wide‐angle X‐ray scattering. The shape of the fibers is mainly influenced by the temperature settings in the melt spinning process. As a reasonable lower limit, a melt spinning temperature of 280°C is identified. Concerning the crystallinity, a saturation going along with a slight reduction of the polymer chain orientation is observed at elevated take‐up velocities. Spinning ; Melt spinning ; Materials science ; Crystallinity ; Composite material ; Scanning electron microscope ; Fiber ; Polymer ; Characterization (materials science) ; Nanotechnology Polymer crystallization and properties ; Fiber-reinforced polymer composites ; Natural Fiber Reinforced Composites
Authors: Thibault Godard | Daniela Zühlke | Georg Richter | Melanie W Wall | Manfred Rohde | Katharina Riedel | Ignacio Poblete‐Castro | Rainer Krull | Rebekka Biedendieck
Source: Frontiers in Bioengineering and Biotechnology (article, 2020-02-21)
Field: Materials Science — Biomaterials

Metabolic Rearrangements Causing Elevated Proline and Polyhydroxybutyrate Accumulation During the Osmotic Adaptation Response of Bacillus megaterium For many years now, <i>Bacillus megaterium</i> serves as a microbial workhorse for the high-level production of recombinant proteins in the g/L-scale. However, efficient and stable production processes require the knowledge of the molecular adaptation strategies of the host organism to establish optimal environmental conditions. Here, we interrogated the osmotic stress response of <i>B. megaterium</i> using transcriptome, proteome, metabolome, and fluxome analyses. An initial transient adaptation consisted of potassium import and glutamate counterion synthesis. The massive synthesis of the compatible solute proline constituted the second longterm adaptation process. Several stress response enzymes involved in iron scavenging and reactive oxygen species (ROS) fighting proteins showed higher levels under prolonged osmotic stress induced by 1.8 M NaCl. At the same time, the downregulation of the expression of genes of the upper part of glycolysis resulted in the activation of the pentose phosphate pathway (PPP), generating an oversupply of NADPH. The increased production of lactate accompanied by the reduction of acetate secretion partially compensate for the unbalanced (NADH/NAD<sup>+</sup>) ratio. Besides, the tricarboxylic acid cycle (TCA) mainly supplies the produced NADH, as indicated by the higher mRNA and protein levels of involved enzymes, and further confirmed by <sup>13</sup>C flux analyses. As a consequence of the metabolic flux toward acetyl-CoA and the generation of an excess of NADPH, <i>B. megaterium</i> redirected the produced acetyl-CoA toward the polyhydroxybutyrate (PHB) biosynthetic pathway accumulating around 30% of the cell dry weight (CDW) as PHB. This direct relation between osmotic stress and intracellular PHB content has been evidenced for the first time, thus opening new avenues for synthesizing this valuable biopolymer using varying salt concentrations under non-limiting nutrient conditions. Bacillus megaterium ; Biochemistry ; Osmotic shock ; Pentose phosphate pathway ; Polyhydroxybutyrate ; Citric acid cycle ; Osmoprotectant ; NAD+ kinase ; Proline ; Biology ; Metabolic pathway ; Osmotic pressure ; Glycolysis ; Chemistry ; Enzyme ; Amino acid ; Bacteria ; Gene biodegradable polymer synthesis and properties ; Biopolymer Synthesis and Applications ; Polyamine Metabolism and Applications
Authors: Isaac J. Gresham | Dennis M. Reurink | Stuart W. Prescott | Andrew Nelson | Wiebe M. de Vos | Joshua D. Willott
Source: Macromolecules (article, 2020-11-18)
Field: Materials Science — Surfaces, Coatings and Films

Structure and Hydration of Asymmetric Polyelectrolyte Multilayers as Studied by Neutron Reflectometry: Connecting Multilayer Structure to Superior Membrane Performance Porous membranes coated with so-called asymmetric polyelectrolyte multilayers (PEMs) have recently been shown to outperform commercial membranes for micropollutant removal. They consist of open support layers of poly(styrene sulfonate) (PSS)/poly(allylamine) (PAH) capped by denser and more selective layers of either PAH/poly(acrylic acid) (PAA) or PAH/Nafion. Unfortunately, the structure of these asymmetric PEMs, and thus their superior membrane performance, is poorly understood. In this work, neutron reflectometry (NR) is employed to elucidate the multilayered structure and hydration of these asymmetric PEMs. NR reveals that the multilayers are indeed asymmetric in structure, with distinct bottom and top multilayers when air-dried and when solvated. The low hydration of the top [PAH/Nafion] multilayer, together with the low water permeance of comparable [PAH/Nafion]-capped PEM membranes, demonstrate that it is a reduction in hydration that makes these separation layers denser and more selective. In contrast, the [PAH/PAA] capping multilayers are more hydrated than the support [PSS/PAH] layers, signifying that, here, densification of the separation layer occurs through a decrease in the mesh size (or effective pore size) of the top layer due to the higher charge density of the PAH/PAA couple compared to the PSS/PAH couple. The [PAH/PAA] and [PAH/Nafion] separation layers are extremely thin (∼4.5 and ∼7 nm, respectively), confirming that these asymmetric PEM membranes have some of the thinnest separation layers ever achieved. Polyelectrolyte ; Neutron reflectometry ; Membrane ; Chemical engineering ; Nafion ; Allylamine ; Styrene ; Acrylic acid ; Permeance ; Sulfonate ; Chemistry ; Polymer chemistry ; Materials science ; Layer (electronics) ; Copolymer ; Permeation ; Polymer ; Small-angle neutron scattering ; Organic chemistry ; Neutron scattering ; Neutron ; Physical chemistry ; Sodium ; Electrochemistry Polymer Surface Interaction Studies ; Membrane Separation Technologies ; Fuel Cells and Related Materials
Authors: David Guzmán | Ilias Papadopoulos | Giulia Lavarda | Parisa R. Rami | Rik R. Tykwinski | M. Salomé Rodríguez‐Morgade | Dirk M. Guldi | Tomás Torres⊗
Source: Angewandte Chemie International Edition (article, 2020-10-01)
Field: Materials Science — Materials Chemistry

Controlling Intramolecular Förster Resonance Energy Transfer and Singlet Fission in a Subporphyrazine–Pentacene Conjugate by Solvent Polarity Due its complementary absorptions in the range of 450 and 600 nm, an energy-donating hexaaryl-subporphyrazine has been linked to a pentacene dimer, which acts primarily as an energy acceptor and secondarily as a singlet fission enabler. In the corresponding conjugate, efficient intramolecular Förster resonance energy transfer (i-FRET) is the modus operandi to transfer energy from the subporphyrazine to the pentacene dimer. Upon energy transfer, the pentacene dimer undergoes intramolecular singlet fission (i-SF), that is, converting the singlet excited state, via an intermediate state, into a pair of correlated triplet excited states. Solvatochromic fluorescence of the subporphyrazine is a key feature of this system and features a red-shift as large as 20 nm in polar media. Solvent is thus used to modulate spectral overlap between the fluorescence of subporphyrazine and absorption of the pentacene dimer, which controls the Förster rate constant, on one hand, and the triplet quantum yield, on the other hand. The optimum spectral overlap is realized in xylene, leading to Förster rate constant of 3.52×10<sup>11</sup> s<sup>-1</sup> and a triplet quantum yield of 171 % ±10 %. In short, the solvent polarity dependence, which is a unique feature of subporphyrazines, is decisive in terms of adjusting spectral overlap, ensuring a sizable Förster rate constant, and maximizing triplet quantum yields. Uniquely, this optimization can be achieved without a need for synthetic modification of the subporphyrazine donor. Singlet fission ; Pentacene ; Intramolecular force ; Polarity (international relations) ; Energy transfer ; Conjugate ; Photochemistry ; Fission ; Solvent polarity ; Solvent ; Singlet state ; Materials science ; Resonance (particle physics) ; Förster resonance energy transfer ; Chemical physics ; Fluorescence ; Chemistry ; Physics ; Atomic physics ; Nanotechnology ; Excited state ; Optics ; Stereochemistry ; Nuclear physics ; Organic chemistry Porphyrin and Phthalocyanine Chemistry ; Luminescence and Fluorescent Materials ; Photochemistry and Electron Transfer Studies
Authors: Selina Beatrice van der Meer | Theresa Seiler | Christin Buchmann | Georgia Partalidou | Sophia Boden | Kateryna Loza | Marc Heggen | Jürgen Linders | Oleg Prymak | Cristiano L. P. Oliveira | Laura Hartmann | Matthias Epple
Source: Chemistry - A European Journal (article, 2020-09-22)
Field: Materials Science — Materials Chemistry

Controlling the Surface Functionalization of Ultrasmall Gold Nanoparticles by Sequence‐Defined Macromolecules Ultrasmall gold nanoparticles (diameter about 2 nm) were surface-functionalized with cysteine-carrying precision macromolecules. These consisted of sequence-defined oligo(amidoamine)s (OAAs) with either two or six cysteine molecules for binding to the gold surface and either with or without a PEG chain (3400 Da). They were characterized by <sup>1</sup> H NMR spectroscopy, <sup>1</sup> H NMR diffusion-ordered spectroscopy (DOSY), small-angle X-ray scattering (SAXS), and high-resolution transmission electron microscopy. The number of precision macromolecules per nanoparticle was determined after fluorescent labeling by UV spectroscopy and also by quantitative <sup>1</sup> H NMR spectroscopy. Each nanoparticle carried between 40 and 100 OAA ligands, depending on the number of cysteine units per OAA. The footprint of each ligand was about 0.074 nm<sup>2</sup> per cysteine molecule. OAAs are well suited to stabilize ultrasmall gold nanoparticles by selective surface conjugation and can be used to selectively cover their surface. The presence of the PEG chain considerably increased the hydrodynamic diameter of both dissolved macromolecules and macromolecule-conjugated gold nanoparticles. Colloidal gold ; Macromolecule ; Nanoparticle ; Nuclear magnetic resonance spectroscopy ; Dynamic light scattering ; Chemistry ; Small-angle X-ray scattering ; Surface modification ; Conjugated system ; Molecule ; Spectroscopy ; Materials science ; Crystallography ; Nanotechnology ; Organic chemistry ; Polymer ; Scattering ; Physical chemistry Nanocluster Synthesis and Applications ; Gold and Silver Nanoparticles Synthesis and Applications ; Nanomaterials for catalytic reactions
Authors: Gernot Pongratz | Vanja Subotić | Hartmuth Schroettner | Bernhard Stoeckl | Christoph Hochenauer | Andrés Anca‐Couce | Robert Scharler
Source: Biomass Conversion and Biorefinery (article, 2020-04-16)
Field: Materials Science — Materials Chemistry

Investigation of solid oxide fuel cell operation with synthetic biomass gasification product gases as a basis for enhancing its performance Abstract Solid oxide fuel cells represent a promising technology to increase the electrical efficiency of biomass-based combined-heat-power systems in comparison to state-of-the-art gas engines, additionally providing high temperature heat. To identify favorable fuel gas compositions for an efficient coupling with gasifiers at low degradation risk is of major importance to ensure stability, reliability, and durability of the systems used, thus increasing attractiveness of electricity production from biomass. Therefore, this study presents a comprehensive analysis on the influence of main gas components from biomass gasification on the performance and efficiency of a cell relevant for real application. An industrial-size electrolyte supported single cell with nickel/gadolinium-doped ceria anode was selected showing high potential for gasifier-solid oxide fuel cell systems. Beneficial gas component ratios enhancing the power output and electric efficiency are proposed based on the experimental study performed. Furthermore, the degradation stability of a SOFC fueled with a synthetic product gas representing steam gasification of woody biomass was investigated. After 500 h of operation under load at a steam-to-carbon ratio of 2.25 in the fuel gas, no performance or anode degradation could be detected. Wood gas generator ; Solid oxide fuel cell ; Biomass (ecology) ; Syngas ; Fuel gas ; Anode ; Waste management ; Process engineering ; Electricity generation ; Chemical engineering ; Materials science ; Environmental science ; Chemistry ; Hydrogen ; Engineering ; Combustion ; Power (physics) ; Coal ; Electrode ; Organic chemistry Advancements in Solid Oxide Fuel Cells ; Electrocatalysts for Energy Conversion ; Fuel Cells and Related Materials
Authors: Sreehari Perumanath | Matthew K. Borg | James E. Sprittles | Ryan Enright
Source: Nanoscale (article, 2020-01-01)
Field: Materials Science — Surfaces, Coatings and Films

Molecular physics of jumping nanodroplets Next-generation processor-chip cooling devices and self-cleaning surfaces can be enhanced by a passive process that requires little to no electrical input, through coalescence-induced nanodroplet jumping. Here, we describe the crucial impact thermal capillary waves and ambient gas rarefaction have on enhancing/limiting the jumping speeds of nanodroplets on low adhesion surfaces. By using high-fidelity non-equilibrium molecular dynamics simulations in conjunction with well-resolved volume-of-fluid continuum calculations, we are able to quantify the different dissipation mechanisms that govern nanodroplet jumping at length scales that are currently difficult to access experimentally. We find that interfacial thermal capillary waves contribute to a large statistical spread of nanodroplet jumping speeds that range from 0-30 m s-1, where the typical jumping speeds of micro/millimeter sized droplets are only up to a few m s-1. As the gas surrounding these liquid droplets is no longer in thermodynamic equilibrium, we also show how the reduced external drag leads to increased jumping speeds. This work demonstrates that, in the viscous-dominated regime, the Ohnesorge number and viscosity ratio between the two phases alone are not sufficient, but that the thermal fluctuation number (Th) and the Knudsen number (Kn) are both needed to recover the relevant molecular physics at nanoscales. Our results and analysis suggest that these dimensionless parameters would be relevant for many other free-surface flow processes and applications that operate at the nanoscale. Jumping ; Molecular motor ; Nanotechnology ; Statistical physics ; Physics ; Biology ; Materials science ; Paleontology Surface Modification and Superhydrophobicity ; Nanomaterials and Printing Technologies ; Fluid Dynamics and Thin Films
Authors: Matej Njegovec | Denis Đonlagić
Source: Sensors (article, 2020-07-02)
Field: Chemistry — Spectroscopy

A Fiber-Optic Gas Sensor and Method for the Measurement of Refractive Index Dispersion in NIR This paper presents a method for gas concentration determination based on the measurement of the refractive index dispersion of a gas near the gas resonance in the near-infrared region (NIR). The gas refractive index dispersion line shape is reconstructed from the variation in the spectral interference fringes' periods, which are generated by a low-finesse Fabry-Perot interferometer during the DFB diode's linear-over-time optical frequency sweep around the gas resonance frequency. The entire sensing system was modeled and then verified experimentally, for an example of a low concentration methane-air mixture. We demonstrate experimentally a refractive index dispersion measurement resolution of 2 × 10<sup>-9</sup> refractive index units (RIU), which corresponds to a change in methane concentration in air of 0.04 vol% at the resonant frequency of 181.285 THz (1653.7 nm). The experimental and modeling results show an excellent agreement. The presented system utilizes a very simple optical design and has good potential for the realization of cost-efficient gas sensors that can be operated remotely through standard telecom optical fibers. Refractive index ; Optical fiber ; Dispersion (optics) ; Fiber optic sensor ; Materials science ; Optics ; Graded-index fiber ; Step-index profile ; Fiber ; Index (typography) ; Refractive index profile ; Normalized frequency (unit) ; Optoelectronics ; Computer science ; Physics ; Composite material Spectroscopy and Laser Applications ; Laser Design and Applications ; Semiconductor Lasers and Optical Devices
Authors: Yanfei Guan | Connor W. Coley | Haoyang Wu | Duminda S. Ranasinghe | Esther Heid | Thomas J. Struble | Lagnajit Pattanaik | William H. Green | Klavs F. Jensen
Source: ChemRxiv (preprint, 2020-09-03)
Field: Materials Science — Materials Chemistry

Regio-Selectivity Prediction with a Machine-Learned Reaction Representation and On-the-Fly Quantum Mechanical Descriptors &lt;div&gt; &lt;div&gt; &lt;div&gt; &lt;p&gt;We introduce a new method that combines machine-learned reaction representation with selected quantum mechanical descriptors to predict regio-selectivity in general substitution reactions. We construct a reactivity descriptor database based on ab initio calculations of 130k organic molecules, and train a multi-task constrained model to calculate demanded descriptors on-the-fly. &lt;/p&gt; &lt;/div&gt; &lt;/div&gt; &lt;/div&gt; Ab initio ; Representation (politics) ; Quantum ; Selectivity ; Construct (python library) ; Chemistry ; On the fly ; Reactivity (psychology) ; Task (project management) ; Molecule ; Substitution (logic) ; Computer science ; Computational chemistry ; Biological system ; Artificial intelligence ; Physics ; Engineering ; Organic chemistry ; Quantum mechanics ; Catalysis ; Biology Machine Learning in Materials Science ; Computational Drug Discovery Methods ; Protein Structure and Dynamics
Authors: Dongxin He | Tao Zhang | Meng Ma | Wenjie Gong | Wei Wang | Qingquan Li
Source: Journal of Nanomaterials (article, 2020-02-03)
Field: Materials Science — Materials Chemistry

Research on Mechanical, Physicochemical and Electrical Properties of XLPE-Insulated Cables under Electrical-Thermal Aging The stabilization of cross-linked polyethylene (XLPE) cables is crucial to the safe working of power systems. In order to investigate the aging characteristics of cable insulation in the process of operation, 10 kV XLPE cables were electrically-thermally aged at an AC voltage of 26.1 kV and three temperatures: 103°C, 114°C, and 135°C. Cable samples at five aging stages were cut into slices and tested to determine their mechanical, physicochemical properties and dielectric strength. The changes in these properties were analyzed in terms of aging time. The mechanical strength and oxidation induction time have the same changing trend of decrease, because the chemical bonds of the cable insulation material are fractured when the XLPE cable is aged. The AC space charge presented a trend of gradual accumulation with aging time. The breakdown field strength after AC voltage application decreases monotonically with aging time, which could be a characteristic index to evaluate the degradation degree of the cable insulation. This research contributes to the comprehension of degradation mechanism and discovery of aging assessment criteria, which is of great significance in assessments of insulation properties and fault detection on power cables. Materials science ; Cross-linked polyethylene ; Composite material ; Accelerated aging ; Polyethylene ; Dielectric strength ; Power cable ; Degradation (telecommunications) ; Voltage ; Dielectric ; Forensic engineering ; Electrical engineering ; Optoelectronics High voltage insulation and dielectric phenomena ; Power Transformer Diagnostics and Insulation ; Electrical Fault Detection and Protection