bluuebunny/crossref_metadata_2025_split huggingface dataset:
Theoretical and experimental investigation of chalcogenide suspended waveguide gas sensor
Authors: Huang Yijun , Wang Xueying , Pi Mingquan , Zhao Huan , Peng Zihang , Min Yuting , Guan Gangyun , Zheng Chuantao , Song Fang , Bai Xue , Wang Yiding 
Published: September 2023

AbstractTo address the issues of low ratio of evanescent field (γ) and high reflectivity between waveguide cross‐section and gas for the mid‐infrared waveguide sensors, we propose a chalcogenide (ChG) suspended waveguide with Ge28Sb12Se60 as the core layer and silica (SiO2) as the buffer layer. The SiO2 beneath the waveguide core ridge structure is removed to create suspended structure. The waveguide sensing performance is obtained using a 10% methane (CH4) sample. The fabricated waveguide exhibits a γ of 112%, which is a 10% improvement compared to a free‐space optical sensor with the same optical path length. The good agreement between the theoretical and experimental results of γ confirms the reliability of our theoretical investigation approach. The influences of fabrication error, environmental temperature, and pressure on sensing performances are discussed. This work provides theoretical guidance for designing waveguide structures with large γ, contributing to the further enhancement of on‐chip sensor performance.
Analysis and application of a local discontinuous Galerkin method for the electromagnetic concentrator model
Authors: Huang Yunqing , Li Jichun , Liu Xin 
Published: September 2023

AbstractIn this paper, we develop a local discontinuous Galerkin (LDG) method to simulate the wave propagation in an electromagnetic concentrator. The concentrator model consists of a coupled system of four partial differential equations and one ordinary differential equation. Discrete stability and error estimate are proved for both semi‐discrete and full‐discrete LDG schemes. Numerical results are presented to justify the theoretical analysis and demonstrate the interesting wave concentration property by the electromagnetic concentrator.
Synthesis and Characterization of Ultra‐Small Gold Nanoparticles in the Ionic Liquid 1‐Ethyl‐3‐methylimidazolium Dicyanamide, [Emim][DCA]
Authors: Hildebrandt Jana , Taubert Andreas , Thünemann Andreas F. 
Published: August 2023

AbstractWe report on gold clusters with around 62 gold atoms and a diameter of 1.15±0.10 nm. Dispersions of the clusters are long‐term stable for two years at ambient conditions. The synthesis was performed by mixing tetrachloroauric acid (HAuCl4 ⋅ 3 H2O) with the ionic liquid 1‐ethyl‐3‐methylimidazolium dicyanamide ([Emim][DCA]) at temperatures of 20 to 80 °C. Characterization was performed with small‐angle X‐ray scattering (SAXS), UV‐Vis spectroscopy, and MALDI‐TOF mass spectrometry. A three‐stage model is proposed for the formation of the clusters, in which cluster growth from gold nuclei takes place according to the Lifshitz‐Slyozov‐Wagner (LSW) model followed by oriented attachment to form colloidal stable clusters.
Exploring service‐providing non‐governmental organization perceptions of shifting civic space in Ghana: Impacts of government and international actors
Authors: Zook Sandy , Krawczyk Kelly Ann , Oduro Franklin 
Published: September 2023

AbstractCivil society space is constantly shifting, either negatively (e.g., shrinking, narrowing) or positively (e.g., expanding). These shifts are predominantly attributed to actions by central government actors, such as the implementation and enforcement of laws. Emergent work, however, also recognizes that in the context of the Global South, the international community can take actions to shrink or expand civil society space. Recently, Ghana in West Africa—known for its democratic stability—has introduced significant legislative and administrative reforms aimed at regulating the NGO sector. We interview 20 Ghanaian service‐providing NGOs to explore perceived shifts in civil society space and the impacts of these shifts, as well as strategies service‐providing NGOs are employing in response to shifting civic space. Findings identify perceived shifts in civic space caused by international actors and the Ghanaian government, as well as strategies for combating and mitigating shifting space.
Numerical simulation of miscible multiphase flow and fluid–fluid interaction in deformable porous media
Authors: Peters Sven , Heider Yousef , Markert Bernd 
Published: September 2023

AbstractThe focus of the underlying research work is on the macroscopic modeling of unstable multiphase fluid flow in deformable porous media, where a lower‐viscous fluid is displaced by a more viscous fluid. This process leads to the formation of channel‐like networks, called viscous fingering. The instability effect is involved in a wide range of different fields in engineering. Some of the most common applications include carbon sequestration to store carbon dioxide (CO2) in underground reservoirs, contaminant transport in geostructures, in industrial processes, such as filtration, catalytic reactions, and in the operation of polymer electrolyte membrane fuel cells with multiphase flow in the gas diffusion layers. In this work, ideal miscible water–glycerin fluids are considered. It is assumed that the interacting fluids in the deformable porous media are incompressible. In addition, a dispersion–diffusion law is applied to capture the fluid–fluid interactions. The presence of a deformable porous material adds additional effects to the problem of the multiphase flow in porous media. The stresses in the porous solid matrix lead to changes in the porosity and influence the flow velocity of the fluids. To couple the deformable porous media with the multiphase flow, a macroscopic approach is used that relies on the theory of porous media. For the porous solid matrix, a linear elastic material model within small strains assumption is applied. The influence of the deformation‐dependent porosity on the instability is studied for 2D simulations, such as a multilayered geometry with different elastic parameters. The presented coupled nonlinear system of differential equations is simulated with the finite element method. Furthermore, a stabilization technique based on the quasi‐compressibility method is used.
Click chemistry‐based azide‐substituted polysulfone/alkynyl‐substituted sulfonated polyvinyl alcohol/nafion blend membranes for direct methanol fuel cells
Authors: Yuan Chengyun , Li Qun , Dong Yunfa , Wang Jiayu , He Weidong , Yan Cenqi , Wang Yinghan , Cheng Pei 
Published: August 2023

AbstractAt present, commercial Nafion membrane is not suitable for proton exchange membrane used in direct methanol fuel cell (DMFC) due to the severe methanol permeation phenomenon. This work reported the preparation and characterization of azide‐substituted polysulfone (PSU‐N3) and alkynyl‐substituted sulfonated polyvinyl alcohol (SAPVA) crosslinked in the matrix of Nafion membrane base on click chemistry applied in DMFC. The compatibility between PSU‐N3 and SAPVA is promoted due to the formation of crosslinked network structure. Key properties, including dimensional stability, oxidative stability, mechanical behavior, methanol permeability and proton conductivity, are compared with those of the recast Nafion membrane. The prepared blend membranes exhibit lower methanol permeability due to the crosslinked network and well‐dispersed microphase structure of PSU‐PVA in the Nafion matrix. The proton selectivity of the Nafion‐PSU‐PVA‐3 membrane is 9.16 × 104 S s/cm3, much higher than that of the recast Nafion membrane (2.82 × 104 S s/cm3). In DMFC single cell tests, the maximum power density of the Nafion‐PSU‐PVA‐3 membrane is 4.6 mW/cm2, about 58.6% higher than that of the recast Nafion membrane. All the results indicate that the prepared blend membranes have the potential to be applied in DMFC.
Rational design of small‐molecule responsive protein switches
Authors: Shui Sailan , Buckley Stephen , Scheller Leo , Correia Bruno E. 
Published: September 2023

AbstractSmall‐molecule responsive protein switches are powerful tools for controlling cellular processes. These switches are designed to respond rapidly and specifically to their inducer. They have been used in numerous applications, including the regulation of gene expression, post‐translational protein modification, and signal transduction. Typically, small‐molecule responsive protein switches consist of two proteins that interact with each other in the presence or absence of a small molecule. Recent advances in computational protein design already contributed to the development of protein switches with an expanded range of small‐molecule inducers and increasingly sophisticated switch mechanisms. Further progress in the engineering of small‐molecule responsive switches is fueled by cutting‐edge computational design approaches, which will enable more complex and precise control over cellular processes and advance synthetic biology applications in biotechnology and medicine. Here, we discuss recent milestones and how technological advances are impacting the development of chemical switches.
Mental health problems in first‐generation university students: A scoping review
Authors: Smith Donna , McLellan Ros 
Published: August 2023

AbstractDespite growing concern about mental health problems in university students and increasing recognition that first‐generation university students (FGS) may face additional challenges, there has been no previous attempt to map the existing research on FGS mental health. The aim of this scoping review was to elicit current understanding of mental health problems in FGS from the literature. Following database searches and screening, 40 peer‐reviewed articles were included in the scoping review. Findings from these studies were synthesised for: types of mental health problems in FGS; prevalence of mental health problems in FGS compared to continuing‐generation students (CGS); factors associated with mental health problems in FGS; effects of mental health problems on FGS; help‐seeking for mental health problems in FGS; and interventions. Significant gaps were highlighted and recommendations made for future research, particularly outside the United States. True commitment to widening participation demands much more research on mental health problems in FGS to ensure that they thrive not just arrive.

Context and implications
Rationale for this studyThe aim of this scoping review was to map the existing international research on mental health problems in first‐generation university students (FGS).Why do the new findings matter?The scoping review synthesises findings from 40 empirical studies published in peer‐reviewed journals, giving valuable insights into mental health problems in FGS and highlighting significant gaps in our understanding.Implications for higher education researchers and universitiesThe findings of the scoping review are a call to action for future research in this field. More studies are needed, particularly outside the United States, using a variety of research designs to gain a more comprehensive understanding of mental health problems in FGS. This research should be prioritised so that universities are provided with evidence‐based recommendations to mitigate and/or address mental health problems in FGS, thereby helping to ensure that they thrive in higher education.
Adaptive mean‐square consensus of heterogeneous multiagent systems with stochastic switching topologies
Authors: Huang Wenchao , Tu Yuhan , Liu Tiantian , Liu Hailin , Tian Binbin , Huang Yanwei , Chen Shaobin 
Published: September 2023

AbstractThe leader–following consensus of linear heterogeneous multiagent systems is investigated in this paper. To comply with the most practical scenario, the communicating topologies among agents are assumed to switch stochastically and driven by a continuous‐time discrete‐state Markov process, whose state space corresponds to all the possible topologies. A novel distributed adaptive compensator is designed for the followers to reconstruct the exogenous signals without knowing the Laplacian matrix who is regarded as a global information, and sufficient conditions are given to ensure the compensator converges to the dynamic of the leader asymptotically in the mean square sense. Then, based on the compensator, we solved the consensus problem both by distributed state and measurement output feedback control schemes under output regulation framework, which allow followers to have nonidentical state dimensions. Finally, the theoretical results are demonstrated by a numerical example.
Expansion of random 0/1 polytopes
Authors: Leroux Brett , Rademacher Luis 
Published: August 2023

AbstractA conjecture of Milena Mihail and Umesh Vazirani (Proc. 24th Annu. ACM Symp. Theory Comput., ACM, Victoria, BC, 1992, pp. 26–38.) states that the edge expansion of the graph of every polytope is at least one. Any lower bound on the edge expansion gives an upper bound for the mixing time of a random walk on the graph of the polytope. Such random walks are important because they can be used to generate an element from a set of combinatorial objects uniformly at random. A weaker form of the conjecture of Mihail and Vazirani says that the edge expansion of the graph of a polytope in is greater than one over some polynomial function of . This weaker version of the conjecture would suffice for all applications. Our main result is that the edge expansion of the graph of a random polytope in is at least with high probability.
One‐pot Multicomponent Synthesis of Novel Chromene Derivatives Using New Organic Phosphate Salt Catalysts
Authors: Salmalian Setareh , Mahmoodi Nosrat O. , Sheykhan Mehdi. 
Published: September 2023

AbstractA new method for synthesizing chromene derivatives as an essential class of heterocyclic compounds has been reported. This research described synthesizing and identifying three new organic salt catalysts based on phosphate moieties. Among the synthesized new phosphate‐based organic salt catalysts, disodium ethyl (phenyl) amino phosphate (DSEAP) plays an essential role and reusable catalyst for the preparation of chromene derivatives under different reaction conditions following the principles of green chemistry. Cost‐effectiveness, non‐toxicity and easy availability are among the salient features of this environmentally friendly catalyst. Furthermore, the catalyst was satisfactorily recycled up to four times without significant performance degradation in the yield of synthesized chromenes. X‐ray diffraction (XRD), infrared spectroscopy (FT‐IR), thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were employed to illustrate the structural and morphologic characteristics of the catalysts. Some synthesized chromene derivatives, including 4I and 4P, showed good antibacterial and biological antioxidant activity compared to the standard drug, respectively. In this research, DSEAP was used as a heterogeneous catalyst in performing one‐pot 3MCRs of aryl aldehyde, an active methylene group e. g. ethyl acetoacetate or diethyl malonate and 5,5‐dimethyl‐1,3‐cyclohexanedione.
DFT Insight into the Kinetics and Mechanism of OH⋅‐Initiated Atmospheric Oxidation of Catechol: Addition of 3∑g− O2 and Isomerization of Peroxy Radicals
Authors: Rahbar Ali , Zahedi Ehsan , Aghaie Hossein , Giahi Masoud , Zare Karim 
Published: September 2023

AbstractAtmospheric oxidation mechanism of predominant catechol‐OH adduct [C6H6O2−OH]⋅ (AD2) by oxygen molecule in its triplet electronic ground state and isomerization processes of catechol peroxy radicals [C6H6O2−OH]⋅−O2 into bicyclic peroxy radicals have been studied at the M06‐2X/aug‐cc‐pVTZ level in conjugation with the RRKM theory. The first step begins via the complexation of [C6H6O2−OH]⋅ with oxygen molecule and formation of two pre‐reactive van der Waals complexes in syn and anti modes. Syn mode addition of O2 is more favorable over the anti mode due to the formation of intramolecular hydrogen bond. Kinetically and thermodynamically, addition of O2 at the C5 position in syn mode, namely peroxy radical AD2‐5OO‐syn, is the most efficient process with bimolecular RRKM rate coefficient 2.80×10−16 cm3 molecule−1 s−1 at ambient conditions. Isomerization (cyclization) of peroxy radical AD2‐5OO‐syn into bicyclic peroxy radicals via the formation of −OO− bridge are strongly endothermic and nonspontaneous processes with high activation energies. Ring closure into the bicyclic peroxy radical AD2‐5,6OO‐syn is the most favorable process with unimolecular RRKM rate coefficient 1.41×10−8 s−1 at ambient conditions.
Synthesis and Recognition Properties of Cd(II) Framework for Highly Selective Sensing of Fe3+, Cr2O72− and CrO42− ions
Authors: Gao Ningning , Zhang Yunyun , Huang Jing , Wang Yan 
Published: September 2023

AbstractIn this study, we successfully constructed a high‐performance fluorescent material for the detection of toxic pollutants in water, [Cd(2‐bpmh)(BDC)H2O]n (1) (2‐bpmh=1,4‐bis(2‐pyridyl)‐2,3‐diaza‐1,3‐butadiene, H2BDC=terephthalic acid), which achieved high yield under the condition of solvothermal reaction. Single crystal X‐ray analysis revealed that complex 1 forms a one‐dimensional chain structure, which is further assembled into a three‐dimensional structure through hydrogen bonding interactions. The luminescence sensing research showed that 1 not only displayed excellent luminescence quenching efficiency, but also could specifically recognize Cr2O72−, CrO42− and Fe3+ ions in water.
Zinc‐Doped BiFeO3 Nanoparticles: Synthesis, Characterization and Photocatalytic Activity on Acid Red‐85 Dye
Authors: Ponraj Caroline , Krishnamoorthi C. , Vinitha G. , Manikandan N. , Santhosh kumar P. , Daniel Joseph 
Published: September 2023

AbstractPhotocatalysis has been drawing significant research attention because of its extensive applications in fields such as environmental remediation and renewable energy. In this work, we design a series of BiFe1‐xZnxO3 (x=0, 0.025, 0.05, 0.075, and 0.1) photocatalysts to reveal the photocatalytic mechanism for model Acid Red‐85, a stable textile dye. The bandgap energy of zinc – doped BiFeO3 is ranging from 2.138 to 2.2 eV. We have shown that changing the Fe/Zn ratio by bandgap engineering effectively controls the reaction pathway. Specifically, BiFe0.925Zn0.075O3 (7.5BFZO) presented the best performance for photocatalytic activity (92 %). The magnetic behaviour improves for lower zinc doping concentrations (x=0.025 and 0.05) and declines for higher concentrations (x=0.075 and 0.10). The photocatalytic degradation of Acid Red‐85 dye followed pseudo first order kinetics, with the highest catalytic effect seen in BiFe0.925Zn0.075O3 with 92 % degradation after 2 hours of light exposure.
Development of Resin Based Spherical Activated Carbon with High Performance Derived from Waste Ion‐Exchange Resin and Its High Effective Removal of Tetracycline
Authors: Li Aiduo , Chen Zhiwei , Ma Cheng , Qiao Wenming , Wang Jitong 
Published: September 2023

AbstractIndustrial production brings billions of tons of solid waste every year, which not only leads to resource waste, but also causes threat to the environment. Improving solid waste resource utilization can better meet the needs of environmental protection and sustainable development. Herein, steam activation method were used to transform the waste ion‐exchange resin (IER) into resin based spherical activated carbons (RSACs) with high adsorption properties and mechanical strength to realize the efficient use of waste resources. The porous structures and mechanical strength of RSACs can be adjusted by changing the reaction conditions including activation temperature, activation time and steam input. The largest specific surface area is up to 2047 m2/g with the pore volume of 1.56 cm3/g. The feasibility of utilizing RSACs to remove tetracycline (TC) from aqueous solution was evaluated, and the highest adsorption capacity is 701 mg/g. The pH variation shows some extent effect on the adsorption. The coexisting ions with higher valence state and concentration result in the decrease of the adsorption capacity to some extent. Additionally, the kinetics experimental data fit the pseudo‐second‐order model well, and the equilibrium data are more consistent with the Freundlich model. The adsorbent is promising in wastewater treatment.
X‐Ray Techniques Dedicated to Materials Characterization in Cultural Heritage
Authors: Magdy Mina 
Published: September 2023

AbstractThis article discusses the basic principles, methodological features, instrumental characteristics, and practical applications of X‐ray techniques in cultural heritage. X‐ray techniques are a set of well‐defined methods for determining the chemical composition and properties of samples. In the field of cultural heritage, material characterization provides valuable information on archaeological materials for understanding heritage assets and ensuring their sustainability. X‐ray fluorescence (XRF) is a versatile method for qualitative and semi‐quantitative elemental analysis. X‐ray diffraction (XRD) is a characterization method to define the properties of the crystal structure of materials. X‐ray photoelectron spectroscopy (XPS) is a chemical tool for understanding the surface chemistry of materials. X‐ray absorption fine structure (XAFS) is a powerful probe for determining the local atomic environment of individual atomic species. X‐ray imaging methods are used for visualization and examination of the objects under study, including X‐ray radiography (XRR) for the non‐destructive inspection of objects, X‐ray computed tomography (XCT) for revealing the internal structure of materials, and dual‐energy X‐ray absorptiometry (DEXA) for the diagnosis of bone health. X‐ray techniques represent key analytical techniques in archaeometric investigations and provide valuable insights into the cultural significance of artifacts.
Bromine Migration and Product Analysis of Waste Printed Circuit Boards during Microwave Steam‐Gasification‐Assisted Pyrolysis
Authors: Li Chunyu , Liu Chengfei , Xia Hongying , Zeng Kangqing , Zhang Libo 
Published: September 2023

AbstractBromine in waste printed circuit boards has caused serious harm to the environment. How to deal with it safely is a problem. In this paper, the debromination of waste printed circuit boards by microwave gasification pyrolysis was studied, and the properties of pyrolysis products and the migration of bromine were analyzed. The optimum pyrolysis conditions of microwave steam atmosphere were 600 °C, 1000 W, 50 min, 2 mL/min. Compared with conventional pyrolysis and conventional steam pyrolysis, less solid products (60.39 wt %) were obtained, and more metal copper was enriched. The content increased from 27.46 % and 28.35 % to 30.63 %, respectively, and the diffraction peak intensity of copper was also enhanced. There is no obvious change in the type of functional groups of the solid product, and its microscopic morphology is smoother. Compared with conventional pyrolysis, the phenolic compounds in pyrolysis oil decreased, and increased compared with conventional steam pyrolysis. The content of H2 in the pyrolysis gas increased significantly, and the content of CO decreased significantly. Compared with conventional pyrolysis, the bromine content in pyrolysis gas and pyrolysis oil decreased from 94.5 % and 5.5 % to 1 %, respectively, and more bromine (98 %) in the raw material entered the aqueous solution.