jablonkagroup/rise_ai_scientists huggingface dataset:
Authors: Wenqi Wang | Zefeng Zhou | Xuanting Tang | Stephanie Moran | Jing Jin | Fredrik Hæffner | Jia Niu
Source:  (preprint, 2021-09-14)
Field: Chemistry — Organic Chemistry

Truly Random Degradable Vinyl Copolymers via Photocontrolled Radical Ring-Opening Cascade Copolymerization Degradable vinyl polymers by radical ring-opening polymerization have become a promising solution to the challenges caused by the widespread use of non-degradable vinyl plastics. However, achieving even distribution of labile functional groups in the backbone of degradable vinyl polymers remains challenging. Herein, we report a photocatalytic approach to truly random degradable vinyl copolymers with tunable main-chain composition via radical ring-opening cascade copolymerization (rROCCP). The rROCCP of the macrocyclic allylic sulfone and acrylates or acrylamides mediated by visible light at ambient temperature achieved near-unity reactivity ratios of both comonomers over the entire range of the comonomer compositions and afforded truly random vinyl copolymers with degradable units evenly distributed in the polymer backbone. Experimental and computational evidence revealed an unusual reversible inhibition of chain propagation by in situ generated sulfur dioxide, which was successfully overcome by reducing the solubility of sulfur dioxide in the reaction mixture. This study provided a powerful approach to truly random degradable vinyl copolymers with tunable main-chain labile functionalities and comparable thermal and mechanical properties to traditional non-degradable vinyl polymers. Comonomer ; Copolymer ; Vinyl polymer ; Polymer ; Polymer chemistry ; Materials science ; Polymerization ; Vinyl alcohol ; Radical polymerization ; Chemistry ; Composite material Advanced Polymer Synthesis and Characterization ; Synthesis and properties of polymers ; Polymer composites and self-healing
Authors: Candyce R. Clark | Eric C. Hosten | Richard Betz
Source: Zeitschrift für Kristallographie - New Crystal Structures (article, 2021-02-14)
Field: Chemistry — Organic Chemistry

The crystal structure of 1,2-bis(1<i>H</i>-benzo[<i>d</i>]imidazol-2-yl)ethane-1,2-diol — <i>N</i>-(2-aminophenyl)-3-(1<i>H</i>-benzo[<i>d</i>]imidazol-2-yl)-2,3-dihydroxypropanamide (1/1), C<sub>32</sub>H<sub>30</sub>N<sub>8</sub>O<sub>5</sub> Abstract C 32 H 30 N 8 O 5 , orthorhombic, P 2 1 2 1 2 1 (no. 19), a = 9.1258(4) Å, b = 10.6225(5) Å, c = 30.1870(14) Å, V = 2926.3(2) Å 3 , Z = 4, R gt ( F ) = 0.0367, wR ref ( F 2 ) = 0.0837, T = 200 K. Orthorhombic crystal system ; Chemistry ; Medicinal chemistry ; Crystal structure ; Stereochemistry ; Crystallography Synthesis of heterocyclic compounds ; Quinazolinone synthesis and applications ; Synthesis and Characterization of Heterocyclic Compounds
Authors: Jared D. Harris
Source: Scholarworks (University of Massachusetts Amherst) (article, 2021-04-01)
Field: Materials Science — Polymers and Plastics

SYNTHESIS AND CHARACTERIZATION OF IMIDAZOLE-CONTAINING CONJUGATED POLYMERS This dissertation examines the relationship between race and educational achievement among inner city, low income, first generation, and high achieving Latino/a students. Research on students of color has focused on <em>cultural deficit models,</em> which portray students as culturally deprived and proposes cultural assimilation as the solution (Nieto 2010; Delpit 2006; Solórzano & Yosso 2002). As a way to contest these models, I describe the role of Academic Support & College Readiness Program (ASP) as a place where <em>community cultural wealth </em>(Yosso 2005) is being created and transferred. Community cultural wealth is an alternative concept that uses Critical Race Theory (CRT) to challenge interpretations of traditional cultural capital theories. It is defined as knowledge, skills and contacts possessed and utilized by Communities of Color to resist different forms of oppression (Yosso 2005; Solórzano & Yosso 2002). While many studies focus on evaluating academic support programs, this study focuses exclusively on students’ experiences and the role of ASP in facilitating their success. I conducted participant observation and forty-seven interviews with students who reside in La Esperanza, a city about forty minutes north of Boston. I explore how they interpret their roles as children of immigrants, high school students, college students, siblings, role models and risk takers. My results highlight the need for scholars and educators to move away from negative discourse regarding students of color and learn more about how communities of color create cultural wealth to resist different forms of oppression. Conjugated system ; Imidazole ; Polymer ; Chemistry ; Characterization (materials science) ; Polymer science ; Nanotechnology ; Materials science ; Organic chemistry Synthesis and properties of polymers ; Epoxy Resin Curing Processes ; Material Properties and Applications
Authors: Ana Mateos Maroto | Irene Abelenda Núñez | Francisco Ortega | Ramón G. Rubio | Eduardo Guzmán
Source: Zenodo (CERN European Organization for Nuclear Research) (article, 2021-04-09)
Field: Materials Science — Surfaces, Coatings and Films

Polyelectrolyte Multilayers on Soft Colloidal Nanosurfaces: A New Life for the Layer-By-Layer Method The Layer-by-Layer (LbL) method is a well-established method for the assembly of nanomaterials with controlled structure and functionality through the alternate deposition onto a template of two mutual interacting molecules, e.g., polyelectrolytes bearing opposite charge. The current development of this methodology has allowed the fabrication of a broad range of systems by assembling different types of molecules onto substrates with different chemical nature, size, or shape, resulting in numerous applications for LbL systems. In particular, the use of soft colloidal nanosurfaces, including nanogels, vesicles, liposomes, micelles, and emulsion droplets as a template for the assembly of LbL materials has undergone a significant growth in recent years due to their potential impact on the design of platforms for the encapsulation and controlled release of active molecules. This review proposes an analysis of some of the current trends on the fabrication of LbL materials using soft colloidal nanosurfaces, including liposomes, emulsion droplets, or even cells, as templates. Furthermore, some fundamental aspects related to deposition methodologies commonly used for fabricating LbL materials on colloidal templates together with the most fundamental physicochemical aspects involved in the assembly of LbL materials will also be discussed. Layer (electronics) ; Polyelectrolyte ; Layer by layer ; Materials science ; Colloid ; Chemical engineering ; Nanotechnology ; Composite material ; Engineering ; Polymer Polymer Surface Interaction Studies ; Hydrogels: synthesis, properties, applications ; Dendrimers and Hyperbranched Polymers
Authors: Yumiao Ma | Zhaohong Wang
Source:  (preprint, 2021-08-18)
Field: Chemistry — Organic Chemistry

Boosting Palladium Catalyzed Aryl–Nitro Bond Activation Reaction by Understanding the Electronic, Electrostatic and Polarization Effect: A Computational Study from Basic Understanding to Ligand Design Although cross coupling reaction with nitroarene as the electrophilic partner has gained high interest recently, the palladium catalyzed aryl–nitro bond activation reaction still requires rather high temperature and hash condition. In this work, based on Nakao’s nitrogen heterocyclic carbene (NHC) ligand, we systematically explored the substituent effect on the oxidative addition step, the known rate determining step of the whole reaction, by density functional theory (DFT) calculation. The key aryl ring on the ligand skeleton, namely Ring A, acts as a π-donor and stabilizes the palladium center of the transition state, as shown by Extended Transition State Natural Orbital of Chemical Valance (ETS-NOCV) analysis, and thus an electron-rich Ring A is expected to lower the barrier. On the other hand, however, the polarization and electrostatic effects were shown to be as or even more important, although they were often ignored before. These effects originate from through-space interaction with the nitro group in the resting state, and the overall effect is that any polarizable or partly negative group nearby the ortho- or meta¬- site of Ring A is harmful for the reaction. Based on these discoveries, we proposed a list of guidelines for successful ligand development, and designed several new ligands. These ligands exhibit significantly lower barrier than the reported Nakao’s ligand by as large as ~5 kcal/mol in both gas phase and solvation, and might be good candidates for further experimental study. Chemistry ; Aryl ; Computational chemistry ; Ligand (biochemistry) ; Electrophile ; Palladium ; Carbene ; Density functional theory ; Photochemistry ; Catalysis ; Organic chemistry ; Alkyl Catalytic Cross-Coupling Reactions ; Catalytic C–H Functionalization Methods ; Nanomaterials for catalytic reactions
Authors: Yumiao Ma | Zhaohong Wang
Source: ChemRxiv (preprint, 2021-08-17)
Field: Chemistry — Organic Chemistry

Boosting Palladium Catalyzed Aryl–Nitro Bond Activation Reaction by Understanding the Electronic, Electrostatic and Polarization Effect: A Computational Study from Basic Understanding to Ligand Design Although cross coupling reactions with nitroarene as the electrophilic partner has gained high interest recently, the palladium catalyzed aryl–nitro bond activation reaction still requires rather high temperature and hash condition. In this work, based on Nakao’s nitrogen heterocyclic carbene (NHC) ligand, we systematically explored the substituent effect on the oxidative addition step, the known rate determining step of the whole reaction, by density functional theory (DFT) calculation. The key aryl ring on the ligand skeleton, namely Ring A, acts as a π-donor and stabilizes the palladium center of the transition state, as shown by Extended Transition State Natural Orbital of Chemical Valance (ETS-NOCV) analysis, and thus an electron-rich Ring A is expected to lower the barrier. On the other hand, however, the polarization and electrostatic effects were shown to be as or even more important, although they were often ignored before. These effects originate from through-space interaction with the nitro group in the resting state, and the overall effect is that any polarizable or partly negative group nearby the ortho- or meta¬- site of Ring A is harmful for the reaction. Based on these discoveries, we proposed a list of guidelines for successful ligand development, and designed several new ligands. These ligands exhibit significantly lower barrier than the reported Nakao’s ligand by as large as ~5 kcal/mol in both gas phase and solvation, and might be good candidates for further experimental study. Chemistry ; Aryl ; Computational chemistry ; Palladium ; Ligand (biochemistry) ; Electrophile ; Carbene ; Density functional theory ; Substituent ; Photochemistry ; Catalysis ; Stereochemistry ; Organic chemistry ; Alkyl Catalytic Cross-Coupling Reactions ; Catalytic C–H Functionalization Methods ; Nanomaterials for catalytic reactions
Authors: Е. Ф. Комарова | O. N. Zhukovskaya | EA Lukbanova | M. A. Yengibaryan | VV Pozdnyakova | Н. Д. Ушакова | YuS Shatova | YuV Przhedetsky | L N Vashenko | Д. А. Харагезов
Source: Bulletin of Russian State Medical University (article, 2021-06-01)
Field: Chemistry — Organic Chemistry

Benzimidazole derivative as antitumor drug against experimentally induced lung carcinoma Most cancer drugs used in a clinical setting are insufficiently effective and insufficiently safe. This prompts the search for novel substances to fight cancer. The aim of this study was to explore the effects of dihydrobromide 2-(3,4-dihydroxyphenyl)-9-diethylaminoethylimidazo[1,2-a] benzimidazole (RU-185) on the growth and metastasis of experimentally induced transplantable Lewis lung carcinoma (LLC). Fifty-five C57/Bl6 male mice (weight 18–20 g) were subcutaneously inoculated with LLC cells. The tested substance (0.5 ml) was administered intragastrically at 50, 220, and 500 mg/kg (groups 1, 2 and 3, respectively) once a day for 10 days starting at 48 h after inoculation. The control group received normal saline. Intragastric administration of the tested substance resulted in significantly longer survival in group 2 only (162.3%) and in the significant reduction of tumor size on day 1 after treatment in all groups. After the end of treatment, tumor sizes in groups 2 and 3 were 3.4 and 1.3 times smaller, respectively, on day 7 and 2.2. and 1.3 times smaller, respectively, on day 14 than in the control group (р &lt; 0,05). The growth delay rate was sustained in group 2 by day 14 after the end of treatment; tumor regression was observed in 20% of the animals. The number of metastases in the lungs was lower in groups 1 and 2 than in the control group (2.6 and 3.1-fold, respectively), and the metastasis inhibition was 68.1% and 80%, respectively. The tested substance RU-185 has an anticancer effect in mice: it results in longer survival, slower growth of the primary tumor and fewer lung metastases of Lewis lung carcinoma. Lewis lung carcinoma ; Benzimidazole ; Medicine ; Metastasis ; Lung cancer ; Saline ; Carcinoma ; Lung ; Internal medicine ; Cancer ; Pharmacology ; Chemistry Synthesis and biological activity ; Synthesis and Characterization of Heterocyclic Compounds ; Synthesis and Biological Evaluation
Authors: Zhong‐Sheng Nong | Ling Zhu | Tian-Ci Wang | Lian‐Feng Fan | Pu‐Sheng Wang | Liu‐Zhu Gong
Source: Research Square (preprint, 2021-10-20)
Field: Chemistry — Inorganic Chemistry

Branch- and Enantioselective Allylic C−H Alkylation Works Well for Almost All Types of α-Alkenes Abstract Asymmetric functionalization of alkenes represents one of the most attractive and straightforward methods to achieve precise assembly of molecular complexity from cost-effectiveness and sustainability viewpoints. Although the regio- and enantioselective transformations on the carbon-carbon double bond of alkenes have been extensively studied, those on the allylic C−H bonds of inactivated alkenes remain to be explored. Here, we report a Pd-catalyzed branch- and enantioselective allylic C−H alkylation, capable of accommodating almost all types of α-alkenes that range from feedstocks annually manufactured on million-ton scale to olefins tethering a wide scope of appended functionalities, providing unconventional access to chiral γ,δ-unsaturated amides. Notably, mechanistic studies reveal that the regioselectivity is not only governed by the coordination pattern of nucleophiles but also regulated by the ligational behaviors of ligands, highlighting the importance of the mono-ligation of chiral phosphoramidite ligands in provoking high levels of stereo- and branch-selectivity via a nucleophile-coordination enabled inner-sphere allylation pathway. Enantioselective synthesis ; Regioselectivity ; Tsuji–Trost reaction ; Allylic rearrangement ; Nucleophile ; Chemistry ; Combinatorial chemistry ; Phosphoramidite ; Alkylation ; Chirality (physics) ; Stereochemistry ; Catalysis ; Organic chemistry Asymmetric Hydrogenation and Catalysis ; Catalytic C–H Functionalization Methods ; Chemical Synthesis and Analysis
Authors: Paolo Quadrelli
Source: ARKIVOC (article, 2021-07-01)
Field: Chemistry — Organic Chemistry

Palladium catalyzed molecular cascades for the synthesis of ethyl 2-methyl-2-(4-methyl-3-(morpholinomethyl)-2-oxopent-3-en-1-yl)-1-oxo-1,2,3,4,5,6-hexahydro-3aH-indene-3a-carboxylate Regiospecific pentamolecular queuing cascades involving the formation of five new bonds have been investigated. The process employs vinyl triflate as starter species together with excess dimethylallene and CO in the presence of in situ generated Pd(0) catalyst and morpholine as capping agent. The investigated reactions were properly tuned up for determining the best conditions allowing to maximizing the desired pentamolecular cascade pathway. The choice of the base, Pd-ligands and reaction temperature as well as the nature of the additive or its presence seem to be pivotal elements that must be tuned for realizing an efficient and reliable process. OTf COOEt H 3 C N H O CO + + + CH 3 Pd(0) COOEt O O H 3 C CH 3 N O (Y. 68% Chemistry ; Palladium ; Catalysis ; Medicinal chemistry ; Stereochemistry ; Organic chemistry Cyclopropane Reaction Mechanisms ; Synthetic Organic Chemistry Methods ; Cancer Treatment and Pharmacology
Authors: V. N. Permyakov | Mikhail Omelchuk
Source: Istrazivanja i projektovanja za privredu (article, 2021-10-21)
Field: Materials Science — Materials Chemistry

Development of methods for assessing the safety of light hydrocarbon storage facilities in emergency situations The risk of accidents involving light hydrocarbons is caused by the physicochemical properties of the components, primarily propane and butane. The most catastrophic accidents involving these substances were on November 19, 1984, in the city of San Juan Ixhuatepec (Mexico) and on June 4, 1989, on the Asha - Ulu-Telyak section (USSR), in each of which more than 500 people died. The novelty of the study is determined by the requirement to ensure industrial and fire safety of storage facilities for light hydrocarbons by predicting probable zones of air flow stagnation. The authors calculated the formation of probable air stagnation zones for various space-planning solutions by using a three-dimensional modelling system and the finite volume method. The paper developed a methodology for assessing the safety of storage facilities for light hydrocarbons in emergency situations, which is based on the analysis of probable air stagnation zones by using three-dimensional modelling systems. The practical significance of the study is determined by the additional development of a parameter for assessing the safety state of a storage facility for light hydrocarbons (Ks) and a resulting parameter (Kr) for calculating the optimal location of structures and their structural changes. Integration of stagnation zone sizes into a single formula with the results of other safety calculations is an urgent scientific and applied problem. Environmental science ; Propane ; Nuclear engineering ; Meteorology ; Engineering ; Geography ; Physics ; Thermodynamics Structural mechanics and materials ; Aerospace, Electronics, Mathematical Modeling ; Wind and Air Flow Studies
Authors: Katrina A. Rieger
Source: Scholarworks (University of Massachusetts Amherst) (article, 2021-04-01)
Field: Materials Science — Biomaterials

Biopolymer Electrospun Nanofiber Mats to Inactivate and Remove Bacteria This dissertation investigates the cognitive mechanism underlying language users' ability to generalize probabilistic phonological patterns in their lexicon to novel words. Specifically, do speakers represent probabilistic patterns using abstract grammatical constraints? If so, this system of constraints would, like categorical phonological generalizations (a) be limited in the space of possible generalizations it can represent, and (b) apply to known and novel words alike without reference to specific known words. I examine these two predictions, comparing them to the predictions of alternative models. Analogical models are specifically considered. In chapter 3 I examine speakers' productions of novel words without near lexical neighbors. Speakers' productions of these novel words are compared to actual (relatively distant) words which could serve as an analogical base. Participants successfully extended a probabilistic trend in the lexicon to novel words, and did not use the analogical bases to do so: the contents of an analogical base for a given nonword did not predict participants' behavior on that nonword. In chapter 4 I discuss a case of mismatch with the lexicon - participants extend a near-categorical trend in the lexicon to novel words, but they undermatch the distribution found in the lexicon. This undermatching would not be predicted if learners could induce arbitrarily complex constraints. I argue instead that the trend is represented grammatically, and that the mismatch arises because of a bias for simpler constraints either in learning or in the structure of the grammar itself. If probabilistic phonological generalizations are represented abstractly, how do they interact with the lexicon of stored word forms? I address this issue in chapter 2 by looking at the perception of known and novel forms. ERP data demonstrates that a productive probabilistic trend influences the early stages of the lexical access process, specifically in known words. I consider two possible mechanisms for this: (1) that the lexical entries of known exceptional forms differ from known trend-observing forms, or (2) that the process of accessing an exceptional form involves a violation of expectations imposed by the grammar, and thus requires more processing power than the process of accessing a trend-observing form. Nanofiber ; Biopolymer ; Electrospinning ; Bacteria ; Polymer science ; Materials science ; Chemistry ; Nanotechnology ; Composite material ; Biology ; Polymer Electrospun Nanofibers in Biomedical Applications
Authors: Zhihao Sun | Zheng Li | Zhongfei Ma | Minxue Zheng | Zhan Wang
Source: Research Square (preprint, 2021-09-02)
Field: Materials Science — Biomaterials

Preparation of Natural Silk Protein-Based Flame Retardant Abstract To counter paper flammability, SF-JR400/MP-SiO 2 sourced from natural silk protein may be applied to the paper surface using layer-by-layer assembly (LbL). The microstructure and composition of the coating may be assessed using SEM, FTIR and XPS. Presence of the coating increases the paper combustion limiting oxygen index (LOI) from 20.4% to 38%. Compared to untreated DBP, TGA analysis shows that the initial decomposition temperature of DBP rises from 115˚C to 148˚C. Residual char yield increases from 11.3% to 38.8%. The formation of a surface char layer protects paper internal fibers from heat feedback and consequent thermal decomposition. Analysis using CONE indicates that a 25-layer assembly can reduce the peak and total heat dissipation by 88.4% and 54.7%, respectively analysis suggests that silk may function as an agent to accelerate the coating, formation of a protective. Char ; SILK ; Fire retardant ; Coating ; Limiting oxygen index ; Materials science ; Thermal decomposition ; Chemical engineering ; Thermogravimetric analysis ; Flammability ; Layer (electronics) ; Composite material ; Fourier transform infrared spectroscopy ; Microstructure ; Pyrolytic carbon ; Combustion ; Pyrolysis ; Chemistry ; Organic chemistry Silk-based biomaterials and applications