bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural, Thermal, Morphological, Adsorption and Catalytic Properties of Poly(BPDAH-co-ODA/PPDA)-Ag/V2O5 Nanocomposites
Authors: Sribala Govindharajan , Meenarathi Balakrishnan , Anbarasan Ramasamy 
Published: February 2020

Thermally stable polyimides (PIs) were prepared by condensation technique at 160 ºC for 5 hours in N-methylpyrrolidone (NMP) medium under N2 atmosphere both in the presence and absence of metal (Ag) and metaloxide (MO) (V2O5) nanoparticles (NPs). The synthesized polymers are characterized by Fourier Transform Infra Red (FT-IR) spectroscopy, 1H Nuclear Magnetic Resonance (1H NMR) spectroscopy, Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy with Energy Dispersive X-Ray (FE-SEM and EDX). The FT-IR spectrum showed a peak at 1786 cm-1 corresponding to the C=O stretching of dianhydride. The aromatic proton signals appeared between 6.7 and 7.5 ppm in the 1H-NMR spectrum of the resultant PIs. The oxydianiline (ODA) based PI with Ag NP loaded system exhibited the highest Tg value. The apparent rate constant values for the adsorption and catalytic reduction of p-nitrophenol (PNP), Cr6+ and rhodamine 6G (R6G) dye were determined with the help of UV-visible spectrophotometer. Among the catalysts, the system loaded with V2O5 NP has higher kapp values. The experimental results are critically analyzed and compared with the previously available literature values. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).
Catalytic Dehydration of Ethanol over W/TiO2 Catalysts Having Different Phases of Titania Support
Authors: Kerdnoi Pongsatorn , Autthanit Chaowat , Chitpong Nithinart , Jongsomjit Bunjerd 
Published: February 2020

This study aims to investigate the catalytic behaviors on W/TiO2 catalysts having different phases of TiO2 towards catalytic dehydration of ethanol to higher value products including ethylene, diethyl ether, and acetaldehyde. In fact, TiO2 support with different crystalline phases can result in differences of physico-chemical properties of the catalyst. Therefore, the present work reports on the catalytic behaviors that were altered with different phases of TiO2 in catalytic ethanol dehydration to diethyl ether or ethylene as a major product. To prepare the catalysts, three different phases [anatase (A), rutile (R), and mixed phases (P25)] of TiO2 supports were impregnated with 10 wt% of tungsten (W). It was found that the W/TiO2-P25 catalyst revealed higher activity among other catalysts. At 300 °C, all catalysts can produce the diethyl ether yield of 24.1%, 22.8%, and 10.6% for W/TiO2-P25, W/TiO2-A, and W/TiO2-R catalysts, respectively. However, when the reaction temperature was increased to 400°C, ethylene is the major product. The W/TiO2-P25 and W/TiO2-A catalysts render the ethylene yield of 60.3% and 46.2%, respectively, whereas only 15.9% is obtained from W/TiO2-R catalyst. The most important parameter influencing their catalytic properties appears to be the proper pore structure, acidity, and distribution of W species. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).
Polymerization of Ethylene Glycol Dimethacrylate (EGDM), Using An Algerian Clay as Eco-catalyst (Maghnite-H+ and Maghnite-Na+)
Authors: Haoue Sara , Derdar Hodhaifa , Belbachir Mohammed , Harrane Amine 
Published: February 2020

In this paper we have explored a novel and green method to synthesis and polymerize ethylene glycol dimethacrylate (EGDM). This technique consists on using Maghnite (Algerian clay) as a green catalyst to replace toxic catalysts. The Algerian clay has been modified using two ion exchange process to obtain Maghnite-H+ (proton exchanged process) and Maghnite-Na+ (sodium exchanged process). Synthesis experiments of EGDM and Poly (EGDM) are performed in bulk respecting the principles of green chemistry. The structure of the obtained monomer and the obtained polymer was confirmed by FT-IR, 1H-NMR and 13C-NMR, where the methacrylate end groups are clearly visible. The presence of unsaturated end group in the structure of monomer was confirmed by UV-Visible analysis. Thermogravimetric analysis (TGA) was used to study the thermal stability of these obtained products. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).
Dynamic Model-Free and Model-Fitting Kinetic Analysis during Torrefaction of Oil Palm Frond Pellets
Authors: Matali Sharmeela , Abd Rahman Norazah , Idris Siti Shawalliah , Yaacob Nurhafizah 
Published: February 2020

Torrefaction is a thermal conversion method extensively used for improving the properties of biomass. Usually this process is conducted within a temperature range of 200-300 °C under an inert atmosphere with residence time up to 60 minutes. This work aimed to study the kinetic of thermal degradation of oil palm frond pellet (OPFP) as solid biofuel for bioenergy production. The kinetics of OPFP during torrefaction was studied using frequently used iso-conversional model fitting (Coats-Redfern (CR)) and integral model-free (Kissinger-Akahira-Sunose (KAS)) methods in order to provide effective apparent activation energy as a function of conversion. The thermal degradation experiments were conducted at four heating rates of 5, 10, 15, and 20 °C/min in a thermogravimetric analyzer (TGA) under non-oxidative atmosphere. The results revealed that thermal decomposition kinetics of OPFP during torrefaction is significantly influenced by the severity of torrefaction temperature. Via Coats-Redfern method, torrefaction degradation reaction mechanism follows that of reaction order with n = 1. The activation energy values were 239.03 kJ/mol and 109.28 kJ/mol based on KAS and CR models, respectively. Copyright © 2020 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).
DES2 is a fatty acid Δ11 desaturase capable of synthesizing palmitvaccenic acid in the arbuscular mycorrhizal fungus Rhizophagus irregularis
Authors: Cheeld Henry , Bhutada Govindprasad , Beaudoin Frederic , Eastmond Peter J. 
Published: February 2020

Arbuscular mycorrhizal (AM) fungi are oleaginous organisms, and the most abundant fatty acyl moiety usually found in their lipids is palmitvaccenic acid (16:1Δ11cis). However, it is not known how this uncommon fatty acid species is made. Here, we have cloned two homologues of lepidopteran fatty acyl‐coenzyme A Δ11 desaturases from the AM fungus Rhizophagus irregularis. Both enzymes, DES1 and DES2, are expressed in intraradical mycelium and can complement the unsaturated fatty acid‐requiring auxotrophic growth phenotype of the Saccharomyces cerevisiae ole1Δ mutant. DES1 expression leads almost exclusively to oleic acid (18:1Δ9cis) production, whereas DES2 expression results in the production of 16:1Δ11cis and vaccenic acid (18:1Δ11cis). DES2 therefore encodes a Δ11 desaturase that is likely to be responsible for the synthesis of 16:1Δ11cis in R. irregularis.
Opiate Receptors
Authors: Zheng Hui , Law Ping‐Yee , Loh Horace H 
Published: February 2020

AbstractMorphine and its congeners are considered to be the best painkilling agents available. The molecular basis for the observed analgesics effects and other pharmacological functions of opioid analgesic drugs are defined by multiple opioid receptors. The opioid receptors are typical G protein‐coupled receptors and activate a variety of downstream signalling pathways via G protein‐ or β‐arrestin‐dependent pathway. Because of the existence of multiple endogenous peptide ligands and the crosstalk with other nonreceptor signalling pathways or neurological circuitries, the pharmacological functions mediated by the multiple opioid receptors are quite complex and are involved in multiple physiological processes, such as the effects on the functions of immune cells and neural stem cells.Key ConceptsThe molecular basis for the observed pharmacological functions of opioid analgesic drugs is defined by multiple opioid receptors.Signalling transduction from opioid receptors is essential for the functions of opioids.As classical GPCR, agonist‐selective signalling can be observed with opioid receptors.Opioid analgesic drugs and opioid receptors contribute to other CNS functions in addition to pain relief.The observed pharmacological functions of opioid analgesic drugs involve nonreceptor elements.
Bacterial Endospores
Authors: Flores Matthew J , Popham David L 
Published: February 2020

Abstract

Species of the genera
Bacillus
and
Clostridium
form dormant, resistant cells are known as endospores in response to stressful conditions. Endospores form inside of a mother cell, or sporangia, via a modified, asymmetrical cell division pathway followed by a variety of spore‐specific modifications to cell structure and content. Once the spore is formed, it is metabolically dormant and highly resistant to various insults such as heat, noxious chemicals, desiccation and UV irradiation. Several significant pathogens are spore formers, which makes disease prevention via food and environment sterilisation challenging. The resistance properties of spores are derived from chemical and physical alterations such as dehydration and mineralisation of the cytoplasm, protective alteration of DNA structure by specialised proteins and formation of impermeable proteinaceous spore coats. Dormancy is ended when the spore enters an environment where spore germination is favourable.

Key Concepts

Bacterial endospores can survive for decades and are highly resistant to numerous environmental insults.

The resistance properties of bacterial endospores contribute to their roles in food spoilage and in human and animal pathogenesis.

Bacterial endospores are cells with specialised modifications to their structure and contents.

Bacterial endospores are produced via a simple developmental process involving cooperative and regulated gene expression of two cells.

Heat resistance of bacterial endospores is determined by several factors, the most important being the relative dehydration of the spore core.

Bacterial endospores possess a unique mode of resistance to UV irradiation involving specialised DNA‐binding proteins.
Bacterial Flagella
Authors: Kühne Caroline , Guse Alina , Hüsing Svenja , Erhardt Marc 
Published: February 2020

Abstract

Bacteria propel themselves through liquid or over semisolid media using rotation of a propeller‐like organelle, the flagellum. The membrane‐embedded basal body is connected via a flexible coupling structure, the hook, to the rigid, external filament. The flagellum is a sophisticated, molecular nanomachine, and to build a flagellum, several thousand copies of more than two dozen proteins assemble in an ordered process. Flagellar gene expression is temporally coupled to its assembly state, and complex self‐assembly mechanisms control the accurate size and subunit composition of flagellar substructures. A specialised protein export machine, termed type‐III secretion system, transports flagellar substrates across the inner membrane. Secreted substrates diffuse through a narrow channel within the flagellum and self‐assemble at the distal end. Intermittent secretion of a molecular ruler protein controls the hook length, while diffusion of flagellin proteins intrinsically limits the length of the flagellar filament.

Key Concepts

Bacteria swim through their environment by rotating an extracellular appendage, the flagellum.

Rotation of the flagellum is energised by influx of ions through stator proteins that are attached to the cell body, which is called the ion motive force.

The bacterial flagellum consists of three major parts: (1) the basal body as the engine, (2) a flexible joint structure, the hook, that connects the engine to (3) the long external filament.

Assembly of the flagellum involves dozens of proteins and the coordination of gene expression to the assembly state of the flagellum.

A specialised protein export system, a type‐III secretion apparatus, is responsible for the export of flagellar secretion substrates, including the majority of the external structures of the flagellum.

Protein export via the flagellar‐specific type‐III secretion system is dependent on the proton motive force.

The length of the hook structure is regulated to an optimal length of 55 nm in
Salmonella
. A molecular ruler controls the final length and catalyses a switch in secretion specificity from early to late substrate secretion mode.

After proton motive force‐dependent injection, flagellin molecules, the building blocks of the filament, diffuse through a narrow channel and self‐assemble at the distal tip of the structure.
Methane Paradox
Authors: Bižić Mina , Grossart Hans‐Peter , Ionescu Danny 
Published: February 2020

Abstract

In contrast to common textbook knowledge, substantial amounts of the potent greenhouse gas methane are produced and emitted from oxygenated freshwater and marine systems. Since this phenomenon contradicts the belief that biological methane production occurs only under strictly anoxic conditions, it was termed the ‘Methane Paradox’. Several biotic and abiotic mechanisms have been suggested to explain the ‘Methane Paradox’. These include the transport of methane from anoxic environments, the formation of microenvironments able to support the classical anaerobic methanogenesis and novel pathways. Among the latter demethylation of methylphosphonates has been proposed as an important pathway in both marine and freshwater systems. Nevertheless, recent studies point to the ability of a broad spectrum of organisms to produce methane independent of the currently known biochemical pathways.

Key Concepts

Methane has roughly 30 times the global warming potential of carbon dioxide by mass over a century.

Methane is emitted from oxygen‐rich environments and not only from anoxic ones as is often stated.

The ‘Methane Paradox’ describes the occurrence of elevated methane concentrations in the upper oxic water column as compared to deeper waters, suggesting local production despite the strict anaerobic nature of all known
Archaea
‐based methanogenic pathways.

Abiotic factors can contribute to the presence of methane in oxic waters and include transport of methane produced in anoxic environments and nonbiological degradation of methylated compounds.

Biotic factors contributing to the presence of methane in oxic waters include local production by microorganisms in anoxic microniches, degradation of methylated compounds and direct, photosynthesis‐related production by phytoplankton like
Cyanobacteria
, diatoms, green algae and
Coccolithofores
.
The Chemistry of Porous Organic Molecular Materials
Authors: Little Marc A. , Cooper Andrew I. 
Published: February 2020

AbstractPorous organic molecular materials are a subclass of porous solids that are defined by their modular, molecular structures, and the absence of extended covalent or coordination bonding in the solid‐state. As a result, porous molecular materials are soluble and they can be processed into different forms, such as mixed matrix membranes. The structure of the porous modules can be fine‐tuned for specific applications, such as gas isotope separations, and in some cases the solid‐state properties of these materials can be defined by the structure of the porous molecule as viewed in isolation. In this review, the authors focus on the design of porous organic molecular materials and how their properties can be tuned for specific applications by using crystal engineering techniques. The authors distinguish between strategies where porosity is defined largely by the molecule itself, for example, in porous organic cages, and cases where porosity is generated by the solid‐state crystalline assembly. They emphasize the importance of computational techniques in the de novo design of functional, porous organic molecular materials, and how molecular modeling is applied to understand the properties of these materials.
Tailoring 2D Heteroatom‐Doped Carbon Nanosheets with Dominated Pseudocapacitive Behaviors Enabling Fast and High‐Performance Sodium Storage
Authors: Jin Qianzheng , Li Wei , Wang Kangli , Li Haomiao , Feng Pingyuan , Zhang Zhuchan , Wang Wei , Jiang Kai 
Published: February 2020

Abstract2D carbon nanosheets are considered to be promising candidates for use as sodium ion battery (SIB) anodes due to their large specific surface area and excellent electronic conductivity. However, their applications are hampered by inferior cycling performance, insufficient storage capacity, and high cost. N, B co‐doping carbon nanosheets (NBTs) are synthesized using biomass‐based gelatin as carbon precursor and boric acid as template, and demonstrate their great potential as high‐performance SIB anodes in practical applications. The synergistic effect of heteroatom doping and ultrathin 2D structure provides the NBTs with abundant defects, active sites, and short ion/electron transfer distance, which favors and improves the storage capabilities and rate performances. The optimized NBTs present a remarkable cyclability and superb rate capability (309 mAh g−1 at 0.2 A g−1 for 200 cycles; 225 mAh g−1 at 1 A g−1 for 2000 cycles). Meanwhile, the Na storage mechanism is proved to be a pseudocapacitive‐controlled process, which accounts for the fast charge/discharge behaviors. This work demonstrates an effective template method to produce 2D heteroatoms co‐doping carbon nanosheets to achieve excellent Na storage performances.
Silica Nanodepletors: Targeting and Clearing Alzheimer's β‐Amyloid Plaques
Authors: Jung Huijin , Chung You Jung , Wilton Rosemarie , Lee Chang Heon , Lee Byung Il , Lim Jinyeong , Lee Hyojin , Choi Jong‐Ho , Kang Hyuno , Lee Byeongdu , Rozhkova Elena A. , Park Chan Beum , Lee Joonseok 
Published: February 2020

AbstractAbnormal accumulation of β‐amyloid (Aβ) peptide aggregates in the brain is a major hallmark of Alzheimer's disease (AD). Aβ aggregates interfere with neuronal communications, ultimately causing neuronal damage and brain atrophy. Much effort has been made to develop AD treatments that suppress Aβ aggregate formation, thereby attenuating Aβ‐induced neurotoxicity. Here, the design of Aβ nanodepletors consisting of ultralarge mesoporous silica nanostructures and anti‐Aβ single‐chain variable fragments, with the goal of targeting and eliminating aggregative Aβ monomers, is reported. The Aβ nanodepletors impart a notable decline in Aβ aggregate formation, resulting in significant mitigation of Aβ‐induced neurotoxicity in vitro. Furthermore, stereotaxic injections of Aβ nanodepletors into the brain of an AD mouse model system successfully suppress Aβ plaque formation in vivo up to ≈30%, suggesting that Aβ nanodepletors can serve as a promising antiamylodoisis material.
Narrowband‐Absorption‐Type Organic Photodetectors for the Far‐Red Range Based on Fullerene‐Free Bulk Heterojunctions
Authors: Xia Kai , Li Yachen , Wang Yan , Portilla Luis , Pecunia Vincenzo 
Published: February 2020

AbstractSpectrally‐selective photodetection via organic semiconductors manifesting narrowband absorption (NBA photodetection) is highly attractive for emerging applications that require ultrathin, lightweight, and low‐cost solutions. While successful over mainstream color bands, NBA photodetectors have struggled so far to meet the functional and/or performance demands at longer wavelengths, importantly in the far‐red (700–750 nm), a range relevant to diverse applications in analytical biology, medical diagnostics, remote sensing, etc. In consideration of the potential of a nonfullerene‐acceptor route to address this challenge, the narrowband photodetection capabilities of SBDTIC, a recently‐developed benzodithiophene‐based acceptor with narrowband absorption in the far‐red, are explored. Two bulk‐heterojunction NBA configurations are considered, in which SBDTIC is combined with a donor either absorbing also in the far‐red, or transparent through the visible. It is found that the latter configuration provides superior narrowband functionality, with peak detectivity of 1.42 × 1013 Jones and spectral width of 141 nm—the highest detectivity to date for NBA far‐red‐selective photodetectors, and the smallest spectral width of all solution‐processed implementations. In self‐powered operation, such photodetectors additionally present a quasilinear response over a photocurrent range of least four orders of magnitude, and respond in the microsecond range, further evidencing the suitability of this approach to address the wealth of target applications.
Synthesis and Application of Heterocyclic Germatranes via Rhodium‐Catalyzed Directed C−H Activation/Annulation with Alkynyl Germatranes and Palladium‐Catalyzed Cross‐Coupling
Authors: Xu Meng‐Yu , Wang Chao , Jiang Wei‐Tao , Xiao Bin 
Published: February 2020

AbstractRhodium‐catalyzed C−H activation and annulation with alkynyl germatranes for the synthesis of heterocyclic germatranes is described. Various heterocyclic germatranes were constructed by this protocol and applied in multiple derivatizations such as palladium‐catalyzed cross‐coupling reactions.magnified image
The Opportunity Cost of the Conservation Reserve Program: A Kansas Land Example
Authors: Taylor Mykel R. , Hendricks Nathan P. , Sampson Gabriel S. , Garr Dillon 
Published: February 2020

AbstractThe effects of the Conservation Reserve Program (CRP) on farmland values is investigated using a set of parcel‐level data for land sales in Kansas over the period 1998 to 2014. The sales data are used to estimate a hedonic model of land values that allows for the opportunity cost of CRP enrollment to vary across space and time. Factors impacting the opportunity costs include the relative productivity of land, returns to farming, and the time remaining under the CRP contracts. We find that the discount associated with having land under CRP contract averages 7%.
Scale‐up analysis of autothermal operation of methane oxidative coupling with La2O3/CaO catalyst
Authors: Sun Zhe , West David H. , Gautam Pankaj , Balakotaiah Vemuri 
Published: February 2020

AbstractThe exothermicity of oxidative coupling of methane (OCM) renders a cooled packed‐bed reactor impractical or impossible. Recently, we proposed an adiabatic autothermal reactor as a solution to this problem and reported the first results for stable autothermal operation (AO) with feed at ambient temperature. AO on the ignited branch is possible only in the region of steady‐state multiplicity. High per‐pass conversion and productivity requirements demand a stable ignited branch at the lowest possible feed temperature and high flow rate. To achieve OCM scale‐up, many conditions must be satisfied simultaneously. Using a kinetic model for La2O3/CaO catalyst, we examine the impact of space time, feed methane to oxygen ratio, feed temperature, particle size, inter‐phase heat and mass transfer gradients, pore‐diffusion, bed scale heat/mass dispersion on the region of AO for large scale adiabatic packed‐bed reactors. We show that while it is possible to achieve CH4 conversion of about 20% and C2 selectivity of about 80% in scaled‐up reactors, these values are sensitive to the design and operating parameters.