bluuebunny/crossref_metadata_2025_split huggingface dataset:
Recent progress in thermal and acoustic properties of natural fiber reinforced polymer composites: Preparation, characterization, and data analysis
Authors: Dev Barshan , Rahman Md. Ashikur , Repon Md. Reazuddin , Rahman Mohammed M. , Haji Aminoddin , Nawab Yasir 
Published: August 2023

AbstractNatural fiber reinforced polymer composites (NFRPCs) have emerged as promising eco‐friendly alternatives over conventional synthetic fiber composites due to their inherent biodegradability, renewability, low environmental impact, and lightweight properties. It has been seen a significant growth in both invention and innovation in the field of NFRPCs. Natural fibers (NFs) reduce the cost of the material by 5%, the weight of the composite by 10%, and the energy required for production by 80%. In terms of thermal, and acoustic properties, NFs can successfully compete with synthetic fibers. As a result, the development of NFRPCs for industrial use has increased significantly in the past decade to meet the growing demands of industrial sectors. To improve the thermal and acoustic properties of NFRPCs, researchers have done a lot of investigation. The aim of the current review is to provide a comprehensive analysis of the existing literature on the thermal and acoustic properties of natural fiber reinforced polymer composites. Thermal properties such as thermal conductivity, TGA, DSC, DMA, and acoustic properties of natural fiber reinforced composites with several parameters, such as different fiber types, different matrix types, fiber weight ratio, fiber to matrix ratio, chemical treatment of fiber have been summarized and analyzed very concisely. This review also emphasizes a summary of different natural fibers, their chemical compositions, composite preparation, characterizations, and future research directions. This article enables the readers, researchers, and manufacturers to realize several opportunities about the latest developments in NFRPCs for the application of thermal and acoustic purposes.HighlightsNatural fibers can successfully compete with synthetic fibers, in terms of thermal and acoustic properties.Thermal properties of natural fiber reinforced composites including thermal conductivity, TGA, DSC, and DMA are summarized.Acoustic properties of natural fiber reinforced polymer composites are discussed.Composite materials made of treated fibers result better thermal stability than untreated fiber composites.Sound absorption coefficient generally increases as fiber content increases.
Mechanical and thermal properties of high volume‐fraction carbon nanotube/epoxy composites, and property enhancement byUVozone treatment of carbon nanotubes
Authors: Kamae Toshiya , Drzal Lawrence T. 
Published: August 2023

AbstractA new method to fabricate carbon nanotube/epoxy composites, consisting of well dispersed and highly concentrated CNTs in an epoxy resin, has been developed. In this method, multiwalled carbon nanotubes (MWNTs) were dispersed into water with the assistance of cationic polymers to form a MWNT sheet by filtration. An epoxy resin was impregnated into the MWNT sheet by vacuum assisted impregnation using a filtration system, followed by autoclave cure, resulting in a MWNT/epoxy composite with a MWNT content of 33 wt%. It was revealed that the composite has a tensile modulus of 8.37 GPa and a tensile strength of 130 MPa. An application of a UV ozone (UV/O3) treatment to the MWNTs increased the XPS O/C ratio from 0.03 to 0.10, resulting in the improvement of the tensile strength to 171 MPa. These results indicate the effectiveness of the UV/O3treated MWTNs for mechanical property enhancement.
Lubrication mechanism of polyimide/V2CTx MXene composites based on surface chemistry
Authors: Jin Lanyu , Wang Xinrui , Huang Yufei , Chen Guojing , Pang Haosheng , Yin Xuan , Chai Chunpeng 
Published: August 2023

AbstractA series of polyimide (PI)/V2CTx MXene composites was synthesized via polyamide acids (PAA) and two‐dimensional (2D) V2CTx MXene obtained by etching precursor V2AlC. PI/V2CTx MXene composites with different mass ratios were obtained by blending and heating with PAA. The results showed that V2CTx MXene has excellent dispersion in PI. In particular, V2CTx MXene exhibited excellent friction reduction and anti‐wear properties as a solid lubricant additive, and the wear rate (WR) was reduced by 43.2% by incorporating only 0.8 wt% of V2CTx MXene in the pristine PI and 71.9% by incorporating 1.2 wt%. Scanning electron microscopy (SEM) and x‐ray photoelectron spectroscopy (XPS) analyses showed that the continuous transfer film consisting of a high proportion of tribo‐chemical products formed on the contact surface is significant to improve the lubrication performances of the PI composites. This work broadens the application of MXene in the field of tribology and contributes to energy conservation and sustainable development of human society.Highlights
The tribological properties could be tuned by changing the ratio of PI to V2CTx MXene.
The WR of PI composites was reduced by 71.9% with incorporating 1.2 wt% of V2CTx MXene.
The formation of transfer films on the contact surface is significant for improving anti‐wear of PI.
Sodium alginate/polyethyleneimine/polydopamine@cellulose nanofiber composite aerogel as a novel adsorbent for Cr(VI) and dyes removal
Authors: Li Jun , Lei Lingling , Liu Zheng , Qiu Jinghong , Wang Haibo 
Published: August 2023

AbstractIn this work, a novel SA/PEI/PDA@CNF (SPCP) aerogel adsorbent was prepared for efficient hexavalent chromium (Cr(VI)) and dyes removal. Sodium alginate was used as the skeleton ingredient, nanocellulose fiber as the reinforcing agent, while polyethyleneimine provides functional groups, and polydopamine was added to improve the adsorption capacity of the aerogel toward cationic dyes. Several methods were used to characterize the SPCP aerogel, and thorough research showed that the aerogel's adsorption capacities for CR, Cr(VI), and MB were 1078.06, 2827.38, and 596.96 mg/g, respectively. In addition, it was established that the pseudo‐second‐order kinetics provides the most accurate way to the adsorption kinetic process while the Langmuir model provides the most accurate representation of the adsorption isotherm. Additionally, SPCP aerogel still retained exceptional adsorption capability after five adsorption‐desorption cycles. Thereupon, SPCP, this biomass composite aerogel exhibits notable benefits, such as high adsorption capacity, marvelous sustainability, cost‐effectiveness, and easy operation, which was considered to be a promising adsorbent for the wastewater treatment.
Nonlinear plasma surface modification of polylactide to promote interaction with fibroblasts
Authors: Kamalov Almaz , Ivanov Aleksey , Smirnova Natalia , Sokolova Maria , Kolbe Konstantin , Pavlov Andrey , Malafeev Konstantin , Yudin Vladimir 
Published: August 2023

AbstractSurface modification of polylactide films was performed using a dielectric barrier discharge (DBD) with the aim of increasing proliferative activity of human fibroblasts on these films. It has been shown that during the plasma treatment of the polylactide film, nonlinear processes occur depending on the processing time. The effect of the dielectric barrier discharge on the modification of polylactide films was evaluated using IR spectroscopy, AFM, XPS, TSDC, and the wetting angle of the surface. The optimal processing time in DBD of polylactide films is 3 min for this installation, the proliferative activity increases by 10% compared to the original film. This treatment time provides an increased concentration of oxygen‐containing groups, optimal relief, and free surface energy of 55 mJ/m2 on the surface.Highlights
The biocompatibility of the polylactide film was improved by 10% used DBD.
The optimal processing time of PLA films in DBD is 3 min.
The functionalization of the polylactide surface occurs non‐linearly.
A novel micromixer for efficient mixing and nano‐TATB preparation
Authors: Guo Yunyan , Zhou Jinqiang , Liu Shujie , An Chongwei , Wang Jingyu , Wu Bidong 
Published: August 2023

AbstractPassive micromixers are widely used in the preparation of ultrafine explosives because of their efficient mixing and necessary safety. A novel passive micromixer was designed to prepare nano‐TATB. Computational fluid dynamics (CFD) is used to simulate the opening width (K), fluid velocity and mixing performance of the micromixer. The results show that the proposed micromixer has good mixing performance in the Reynolds number (Re) range of 0.1~100, and its pressure drop less than 28204 Pa at Re=100. A microfluidic recrystallization system was established and nano‐TATB was prepared by a new micromixer. The results show that the average particle size of the prepared TATB is 93.12 nm, and the particle size distribution ranges from 43 nm to 151.4 nm. The SEM test shows that TATB has better morphological characteristics. XRD results show that the crystal structure of TATB is consistent with that of raw materials. This study proves that the new micromixer has good mixing effect and the feasibility of preparing nano TATB. It also provides reference for the design of micromixer and refinement of other energetic materials.
Electrostatic hazards: Identifying the early warning signs to reduce explosion risk1
Authors: Ebadat Vahid , Cartwright Paul 
Published: August 2023

AbstractElectrostatic discharges are known to cause many industrial fires and explosions each year. Yet it is quite usual to find that before an incident operatives have encountered signs that static electricity is present. These signs—the ‘early warning signs’—had their significance been appreciated, could have prevented many industrial fires or explosions. In this paper, we bring together evidence obtained from investigation of electrostatic incidents and group them by class of ‘manifestation’. We discuss how these classes/manifestations should be interpreted by reference to discharge types and their associated energy ranges. Finally, we discuss how we can go about assessing whether each static manifestation could lead to an electrostatically initiated fire or explosion as well as how they can be eliminated. The early warning signs of static electricity can be as apparently innocuous as dust patterns on plastic or a prickling feeling on the arms. They can also include unexpected corrosion in a glass‐lined vessel or even a pinhole leak from an insulating pipe; these in addition to the well‐recognized sparks and cracking sounds that present themselves as the more obvious face of hazardous static electricity. Waiting for an ‘early warning sign’ can never be a substitute for detailed hazard assessment work that focuses on the identification and elimination of all potential ignition sources. But it is worth noting that electrostatic sources of ignition are often considered to be more complicated to identify and eliminate than others, and consequently, they frequently elude the formal HAZOP or hazard study process. With electrostatic hazards, this makes vigilance by operatives and others that much more important, especially since electrostatic effects can easily be spotted and eliminated—if you know what to look for. A new proposed ‘classification’ that will be discussed in this paper can aid the understanding of hazardous static electricity and thus help reduce the risk of fire and explosion in industry.
Wind turbine gear reliability analysis considering dependent competing failure
Authors: Liu Yuanyuan , Gao Jianxiong , Yuan Yiping , Wang Shuo 
Published: August 2023

AbstractTo more precisely assess the reliability of wind turbine gears, a competing failure model is established with consideration given to the degradation of internal fatigue strength and external random shocks. Firstly, the nonlinear Gamma process is adopted to depict the degradation of fatigue strength, and the strength‐stress interference theory is used to establish the threshold of degradation failure that changes over time. Also, the non‐homogeneous Poisson process is employed to depict the arrival of the shock, and classification of the shocks. Secondly, the correlation between degradation and shock is described, while the effect of shocks on degradation is demonstrated as a sudden increase in the extent of degradation. Besides, the decline rate of residual strength curve is introduced to describe the change in intensity parameters of the Poisson process, and then the effect of degradation on shocks is described. Finally, the sun gear in the wind turbine gearbox is an example. Monte Carlo simulation is used to calculate the reliability of the dependent competing failure model. This is then compared with the conventional stress‐strength interference model. The results verify that when the relationship between degradation and the shock process is disregarded, the reliability of gears may be overestimated.
Transmission reliability evaluation of the wireless mobile ad hoc network considering the routing protocol and randomness of channel capacity
Authors: Wang Ning , He Jiatao , Xiang Shihu , Yang Jun 
Published: August 2023

AbstractDue to the characteristics of self‐organization, flexibility, and low cost, Mobile ad hoc networks (MANETs) have been applied in many fields, such as disaster rescues and military actions. However, in reality, the successful route establishment based on routing protocols is the prerequisite of data transmission. Besides, the transmission reliability of MANETs is affected by resource constraints, such as channel capacity and energy, and environmental factors. Hence, how accurately modeling and evaluating the transmission reliability of MANETs is very important to ensure their application. Whereas, existing studies ignore the impact of routing protocols and do not fully consider the influence of some factors on transmission reliability, such as environmental randomness, channel capacity, and energy consumption. To solve the above problems, we first propose a signal‐to‐noise‐ratio‐Capacity connection model to better describe the characteristics of wireless links, and the probability of one hop connection is deduced considering the capacity demand randomness. Then, considering the influence of routing protocol on the MANET link establishment, we take the ad hoc on‐demand distance vector routing protocol as an example, and propose an evaluation algorithm of the MANET transmission reliability based on algebraic graph theory and Monte Carlo simulation. Finally, the effectiveness of the proposed method is demonstrated by a numerical example of an unmanned aerial vehicle search and rescue scene.
Sustainable urbanization and vulnerability to climate change in Africa: Accounting for digitalization and institutional quality
Authors: Yeyouomo Aurelien K. , Asongu Simplice A. 
Published: August 2023

AbstractThis study empirically examines the effect of sustainable urbanization on vulnerability to climate change over a sample of 52 African countries from 1996 to 2019. We use the two‐stage system generalized method of moments (GMM) empirical strategy and mediation analysis to assess direct and indirect impacts, respectively. The results of the direct analysis reveal that sustainable urbanization reduces vulnerability to climate change. The results of the indirect analysis also show that sustainable urbanization significantly reduces vulnerability to climate change through the channels of digitalization and institutional quality. The results also highlight that considering the direct effect of sustainable urbanization alone underestimates the impact of reducing vulnerability to climate change. The results are robust to an alternative indicator of vulnerability to climate and other estimation techniques. These results have important policy implications and provide evidence for the improvement of sustainable urbanization in terms of access to basic services or reduction of vulnerability to climate change.
After the startup: A collection to spur research about entrepreneurial growth
Authors: Combs James G. , Ketchen David J. , Terjesen Siri A. , Bergh Donald D. 
Published: August 2023

AbstractResearch SummaryEntrepreneurship researchers have made great strides toward understanding who discovers and/or creates opportunities, how they validate a business model, and how they attract resources, but far less is known about what happens next. Beyond gathering resources, how do entrepreneurs build a growing organization once customer enthusiasm has been demonstrated? What has been learned is fragmented across theoretical perspectives and activities related to growth. We describe a collection of articles that spotlight different theories and organize the articles according to key activities: (1) building internal resources and capabilities, (2) leveraging partnerships, (3) taking strategic actions, and (4) managing interactions among resources, partners, and actions. Juxtaposing these activities with theories from the collection, we offer a research agenda designed to spur research to fill gaps in understanding of how entrepreneurs successfully manage growth.Managerial SummaryThe period of an organization's development between the startup stage and becoming an established firm presents unique challenges. We spotlight a set of articles that have provided insights into how organizations can overcome these challenges. We then add our own perspective by providing research ideas that scholars can investigate in order to generate additional insights.
Declining science‐based startups: Strategic human capital and the value of working in startups versus established firms
Authors: Ding Yuheng , Åstebro Thomas , Braguinsky Serguey 
Published: August 2023

AbstractResearch SummaryWe document that since 1997, the rate of startup formation has precipitously declined for firms operated by US PhD recipients in science and engineering. We explore how increasing knowledge complexity can be associated with fewer science‐based startups. The decline in startup formation is accompanied by an earnings decline, increasing work complexity in R&D, and more administrative work for science‐based founders. Founding a startup appears to have become increasingly harder over the past 20 years, while established firms are becoming more attractive workplaces for PhDs.Managerial SummaryThe increase in knowledge complexity has changed the balance of incentives between starting own business versus working for an incumbent firm in favor of the latter for PhDs. If maintaining a steady flow of new businesses in the high‐tech sector is important to keep the flow of commercialization of new ideas coming, managerial practitioners and policy makers may need to find ways to make the job of the founder more attractive. The findings in this article point to the importance of secularly increasing value of complementary assets in work practices, especially for founders and employees that are high value generators. Alternatively, the increasing dominance of a few very large tech firms that the increasing burden of knowledge is fueling could be just fine, and startups need not play an important role in economic development.
Reduction and Adsorption of Hexavalent Chromium by Iron Sulfide Loaded Biochar: Isotherms, Kinetics and Thermodynamics
Authors: Qhubu Mpho Cynthia , Lesaoana Mahadi , Nomngongo Philiswa Nosizo , Pakade Vusumzi Emmanuel 
Published: August 2023

AbstractThe removal of noxious Cr(VI) from water has gained worldwide attention. In this study, biochar derived from macadamia nut shells (MHP) was embedded with iron sulfide (FeS) nanoparticles produced through a solid‐phase reduction of pyrite. The MHP‐FeS composite was evaluated for the adsorption of Cr(VI) and its subsequent reduction to Cr(III). The scanning electron microscope images revealed that the particles were of irregular shape, while the energy dispersive spectroscopy results showed the existence of Fe, S, O, and C atoms. X‐ray diffraction peaks at 2=29.8°, 33.7°, 43.7°, and 53.1° were characteristic of the formation of FeS nanoparticles. A maximum Cr(VI) adsorption capacity of 4.95 mg/g was obtained at pH 3, 60 min, and 25 °C. The higher correlation coefficient (R2>0.873) and lower residual standard error (RSE=1.43) values pointed to the adsorption process favoring Langmuir and pseudo‐second‐order models. As per thermodynamic reaction calculations, the remediation process was spontaneous and endothermic. With further optimization, this material could be a potential adsorbent and reductant for Cr(VI) in water.
A Facile Regio‐ and Stereoselective Synthesis and Cholinesterase Inhibitory Activity of New Oxobenzothiophene Grafted Spiropyrrolidine/Pyrrolizidine Hybrids Employing Multicomponent 1,3‐Dipolar Cycloaddition Methodology
Authors: Raju Rajesh , Mani Suresh , Arumugam Natarajan , Almansour Abdulrahman I. , Suresh Kumar Raju , Premnath Dhanaraj , Perumal Karthikeyan 
Published: August 2023

AbstractA stereo‐, regio‐ and chemoselective synthesis of a series of structurally diverse novel oxobenzothiophene embedded spirooxindolopyrrolidine/pyrrolizidine hybrid heterocycles were achieved in excellent yields by multicomponent 1,3‐dipolar cycloaddition reaction process. The 1,3‐dipole component employed was generated in situ from isatin and N‐methylglycine/L‐proline while the dipolarophile, ethyl 2‐(3‐oxobenzo[b]thiophen‐2(3H)‐ylidene)acetate was prepared from thiophenol in two good yielding steps. The formation of spiroheterocyclic hybrids occurred through the formation of two C=C and one C−N bonds in a single synthetic transformation. The compounds formed consists of three adjacent stereocenters, out of which two are spirocarbons. The synthesized spiro compounds were assayed for their AChE/BChE inhibitory activity and most of the spirocompounds showed promising cholinesterase inhibitory activity. Among them, spiropyrrolidine that substituted with chlorine atom on the oxindole ring displayed significant activity (4.16±0.09 μM) with respect to standard drug, galantamine (2.09±0.11 μM). Molecular modelling simulation was explored for the most potent compound that revealed interesting binding templates to the active site of enzyme.
Design, Synthesis, Antimicrobial and Docking Studies of Benzothiazoles Bearing Pyrazole and Pyrimidine Moieties
Authors: Tamam Esraa , Fadda Ahmed A. , El‐Sawy Eslam R. , Abdel‐Aziz Mohamed S. , Tawfik Eman H. 
Published: August 2023

AbstractThe reaction of enaminonitrile 2 with hydrazine hydrate yielded 5‐amino pyrazole derivative 4. Compound 4 reacted with ethyl acetoacetate, enaminone 8, chalcone 12, enaminonitrile 2, arylidene malononitrile 18, 3‐(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)‐3‐oxopropanenitrile 21 and phenacyl bromide to give the corresponding pyrazolopyrimidine derivatives 7, 11, 14, 17, 20, 23, and imidazopyrazole 25, respectively. The newly synthesized compounds were characterized by spectral and elemental analyses. The antimicrobial activities of the new compounds were tested against S. aureus, E. coli, and C. albicans. It was found that compound 23 exhibited the highest antimicrobial activity against the tested microorganisms. All tested compounds did not have antifungal activity against A. niger as a fungal strain. Utilizing drug‐likeness (ADME) and molecular docking the effectiveness of compound 23 towards G+ve and G‐ve bacteria has been studied. Accordingly, compound 23 is expected to have a high chance of oral bioavailability due to its compliance with Lipinski′s rule of five. In addition, it plays a critical role in the inhibition of bacterial S. Ribosome, dihydropteroate synthase, transpeptidase, and gyrase B. subunit proteins.