bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental methods in chemical engineering: High performance liquid chromatography—HPLC
Authors: Schieppati Dalma , Patience Nicolas A. , Campisi Sebastiano , Patience Gregory S. 
Published: January 2021

AbstractHigh performance liquid chromatography (HPLC) identifies compounds in a sample and quantifies their concentration. The instrument consists of an injector that introduces a μL sample to a mobile phase that carries the analytes across a column filled with an adsorbing substance. The analytes adsorb and desorb at different rates as they flow down the column and are thereby separated. Detectors record a signal proportional to the concentration of the analyte in the mobile phase. Laboratories apply modern HPLC systems for research and development, quality control, safety, and validation. Academia and industry resort to HPLC to purify, identify, and characterize a wide variety of molecules at all stages of a process. Developing an HPLC analytical method is a long and laborious process requiring standards, calibration curves, derivatization, and multiple tests to identify an appropriate column, stationary phase, flow rate, temperature, and mobile phase. Optimal operating conditions maintain a good resolution (high signal‐to‐noise ratio and low peak overlap) while minimizing analysis time. Web of Science Core Collection indexed 8900 articles in 2019, which is relatively few compared to x‐ray and scanning electron microscopy. However, it is such an ubiquitous technique and we estimate that the number of articles that report it in the experimental section is an order of magnitude higher. The bibliometric analysis of the keywords identified four research clusters: phenolics and flavonoids, extraction and pharmacokinetics, in vitro and oxidative stress, and optimization. Here, we detail a walkthrough for the basic steps required to develop a chromatographic method.
Safe chemistry lessons – the check of substitute substances using the example of traditional solvents
Authors: Klemeyer Horst 
Published: January 2021

AbstractAm Beispiel der Ester aus primären n‐Alkanolen mit unverzweigten gesättigten Carbonsäuren wird aufgezeigt, wie unter Anwendung des GHS‐Spaltenmodells zur Ersatzstoffprüfung sicherheitsoptimierte Synthesen für den Unterricht mit Schülerfreihandversuchen ausgewählt werden können. Es gelingt dabei, Situationen zu vermeiden, bei denen Stoffe mit einem hohen Freisetzungsverhalten, leichter Entzündbarkeit und chronischen Gesundheitsgefahren verwendet werden. Der Unterricht mit den Estern, die als natürliche Aromen bedeutsam sind, kann bei Schülerinnen und Schüler schon aufgrund der olfaktorischen und affektiven Wirkung sehr motivierend sein. Hier wird aufgezeigt, wie dies noch durch haptische und praktische Arbeiten unterstützt werden kann. Zudem wird für den Unterricht das Netzdiagramm als Hilfsmittel zur Beschreibung von Gerüchen vorgestellt.
Preparing (Metalla)carboranes for Nanomedicine
Authors: Gozzi Marta , Schwarze Benedikt , Hey‐Hawkins Evamarie 
Published: January 2021

Abstract“There's plenty of room at the bottom” (Richard Feynman, 1959): an invitation for (metalla)carboranes to enter the (new) field of nanomedicine. For two decades, the number of publications on boron cluster compounds designed for potential applications in medicine has been constantly increasing. Hundreds of compounds have been screened in vitro or in vivo for a variety of biological activities (chemotherapeutics, radiotherapeutics, antiviral, etc.), and some have shown rather promising potential for further development. However, until now, no boron cluster compounds have made it to the clinic, and even clinical trials have been very sparse. This review introduces a new perspective in the field of medicinal boron chemistry, namely that boron‐based drugs should be regarded as nanomedicine platforms, due to their peculiar self‐assembly behaviour in aqueous solutions, and treated as such. Examples for boron‐based 12‐ and 11‐vertex clusters and appropriate comparative studies from medicinal (in)organic chemistry and nanomedicine, highlighting similarities, differences and gaps in physicochemical and biological characterisation methods, are provided to encourage medicinal boron chemists to fill in the gaps between chemistry laboratory and real applications in living systems by employing bioanalytical and biophysical methods for characterising and controlling the aggregation behaviour of the clusters in solution.
Magnetic line source diffraction by a conductive half‐plane in an anisotropic plasma
Authors: Basdemir Husnu Deniz 
Published: January 2021

AbstractAn integral theory that is associated with the scattered fields is considered for the solution of H‐polarized line source diffraction by a conductive half‐plane, which is surrounded by an anisotropic plasma. As the anisotropy does not affect an E‐polarized incident wave, only one polarization case is considered. The cold plasma medium is characterized by the dielectric tensor. The constant external magnetic field producing the anisotropy in a cold plasma is applied parallel to the edge of the half‐plane. The total, scattered, and diffracted waves are derived in terms of the Fresnel functions. Therefore, finite magnitude values at the transition boundaries are obtained. The wave behaviours are investigated numerically for different quantities of the medium.
Ion energy distribution in a radio frequency sheath of plasma with Kappa electron velocity distribution
Authors: Ou Jing , Huang Yueheng 
Published: January 2021

AbstractA hybrid model consisting of a one‐dimensional radio frequency sheath model and an equivalent circuit model is used to investigate the effect of the non‐Maxwellian plasma with enhanced electron tails on ion energy distribution (IED) at the plasma–wall interface. With the assumption that electrons obey the Kappa distribution in which the parameter κ characterizes the deviation from Maxwellian distribution, the bimodal shape of the IED can always be found with the decrease of κ under the condition of current experimental advanced superconducting tokamak (EAST) discharges during the ion cyclotron range of frequency wave heating. However, the height of the low‐energy peak of the IED decreases, while the high‐energy peak does not change significantly. In addition, the IED shifts towards the higher‐energy regime, and the width of the IED expands with the decrease of κ. It is also shown that frequency and amplitude of the disturbance current, bulk plasma density, and ion temperature are the crucial parameters for determining the shape of IED even in the presence of super‐thermal electrons.
Macroion effective charge in complex plasmas with regard to microion correlations
Authors: Martynova Inna A. , Iosilevskiy Igor L. 
Published: January 2021

AbstractIn the present paper, features of high‐charged macroions screening by microions are analysed in classical asymmetrically charged complex plasmas. We consider a two‐component electroneutral system of classical macroions and oppositely charged microions in a spherically symmetrical electroneutral Wigner–Seitz cell with a central macroion in its centre. The present paper is devoted to a problem of a relation between the effective macroion charge and an initial one with regard to a non‐linear screening effect and microions correlations. We show how this relation changes with the number of the central macroion charge value on the rise. Characteristics of two different parts of the relation between the effective charge and the initial one are calculated.
Teaching an experiential field course via online participatory science projects: A COVID‐19 case study of a UC California Naturalist course
Authors: Gerhart Laci M. , Jadallah Christopher C. , Angulo Sarah S. , Ira Gregory C. 
Published: January 2021

AbstractExperience and training in field work are critical components of undergraduate education in ecology, and many university courses incorporate field‐based or experiential components into the curriculum in order to provide students hands‐on experience. Due to the onset of the COVID‐19 pandemic and the sudden shift to remote instruction in the spring of 2020, many instructors of such courses found themselves struggling to identify strategies for developing rigorous field activities that could be completed online, solo, and from a student's backyard. This case study illustrates the process by which one field‐based course, a UC California Naturalist certification course offered at the University of California, Davis, transitioned to fully remote instruction. The transition relied on established, publicly available, online participatory science platforms (e.g., iNaturalist) to which the students contributed data and field observations remotely. Student feedback on the course and voluntary‐continued engagement with the participatory science platforms indicates that the student perspective of the experience was on par with previous traditional offerings of the course. This case study also includes topics and participatory science resources for consideration by faculty facing a similar transition from group field activities to remote, individual field‐based experiences.
Georeferenced phylogenetic analysis of a global collection of wild and cultivated Citrullus species
Authors: Achigan‐Dako Enoch G. , Degbey Hervé , Hale Iago , Blattner Frank R. 
Published: January 2021

AbstractThe geographical origin of watermelon (Citrullus lanatus) remains debated. While a first hypothesis suggests the center of origin to be West Africa, where the endemic sister species C. mucosospermus thrives, a second hypothesis suggests northeastern Africa where the white‐fleshed Sudanese Kordophan melon is cultivated. In this study, we infer biogeographical and haplotype genealogy for C. lanatus, C. mucosospermus, C. amarus, and C. colocynthis using noncoding cpDNA sequences (trnT‐trnL and ndhF‐rpl32 regions) from a global collection of 135 accessions. In total, we identified 38 haplotypes in C. lanatus, C. mucosospermus, C. amarus, and C. colocynthis; of these, 21 were found in Africa and 17 appear endemic to the continent. The least diverse species was C. mucosospermus (5 haplotypes) and the most diverse was C. colocynthis (16 haplotypes). Some haplotypes of C. mucosospermus were nearly exclusive to West Africa, and C. lanatus and C. mucosospermus shared haplotypes that were distinct from those of both C. amarus and C. colocynthis. The results support previous findings that revealed C. mucosospermus to be the closest relative to C. lanatus (including subsp. cordophanus). West Africa, as a center of endemism of C. mucosospermus, is an area of interest in the search of the origin of C. lanatus. This calls for further historical and phylogeographical investigations and wider collection of samples in West and northeastern Africa.
Effects of experimental watering but not warming on herbivory vary across a gradient of precipitation
Authors: Pepi Adam , Karban Richard 
Published: January 2021

AbstractClimate change can affect biotic interactions, and the impacts of climate on biotic interactions may vary across climate gradients. Climate affects biotic interactions through multiple drivers, although few studies have investigated multiple climate drivers in experiments. We examined the effects of experimental watering, warming, and predator access on leaf water content and herbivory rates of woolly bear caterpillars (Arctia virginalis) on a native perennial plant, pacific silverweed (Argentina anserina ssp. pacifica), at two sites across a gradient of precipitation in coastal California. Based on theory, we predicted that watering should increase herbivory at the drier end of the gradient, predation should decrease herbivory, and watering and warming should have positive interacting effects on herbivory. Consistent with our predictions, we found that watering only increased herbivory under drier conditions. However, watering increased leaf water content at both wetter and drier sites. Warming increased herbivory irrespective of local climate and did not interact with watering. Predation did not affect herbivory rates. Given predictions that the study locales will become warmer and drier with climate change, our results suggest that the effects of future warming and drying on herbivory may counteract each other in drier regions of the range of Argentina anserina. Our findings suggest a useful role for range‐limit theory and the stress‐gradient hypothesis in predicting climate change effects on herbivory across stress gradients. Specifically, if climate change decreases stress, herbivory may increase, and vice versa for increasing stress. In addition, our work supports previous suggestions that multiple climate drivers are likely to have dampening effects on biotic interactions due to effects in different directions, though this is context‐dependent.
Male‐biased dispersal in a fungus‐gardening ant symbiosis
Authors: Matthews Alix E. , Kellner Katrin , Seal Jon N. 
Published: January 2021

AbstractFor nearly all organisms, dispersal is a fundamental life‐history trait that can shape their ecology and evolution. Variation in dispersal capabilities within a species exists and can influence population genetic structure and ecological interactions. In fungus‐gardening (attine) ants, co‐dispersal of ants and mutualistic fungi is crucial to the success of this obligate symbiosis. Female‐biased dispersal (and gene flow) may be favored in attines because virgin queens carry the responsibility of dispersing the fungi, but a paucity of research has made this conclusion difficult. Here, we investigate dispersal of the fungus‐gardening antTrachymyrmex septentrionalisusing a combination of maternally (mitochondrial DNA) and biparentally inherited (microsatellites) markers. We found three distinct, spatially isolated mitochondrial DNA haplotypes; two were found in the Florida panhandle and the other in the Florida peninsula. In contrast, biparental markers illustrated significant gene flow across this region and minimal spatial structure. The differential patterns uncovered from mitochondrial DNA and microsatellite markers suggest that most long‐distance ant dispersal is male‐biased and that females (and concomitantly the fungus) have more limited dispersal capabilities. Consequently, the limited female dispersal is likely an important bottleneck for the fungal symbiont. This bottleneck could slow fungal genetic diversification, which has significant implications for both ant hosts and fungal symbionts regarding population genetics, species distributions, adaptive responses to environmental change, and coevolutionary patterns.
Evaluation and speciation of cobalt, copper, and zinc in saline soil bymicrowave‐assistedsingle extraction
Authors: Waris Muhammad , Kazi Tasneem G. , Baig Jameel A. 
Published: January 2021

AbstractThe present research assessed the chemical fractionation of Cobalt (Co), Copper (Cu), and Zinc (Zn), detected in saline soil samples of Hyderabad Pakistan. The partitioning of Co, Cu, and Zn in soil samples was carried by single‐step extraction using microwave irradiation energy. The validity of the methods was confirmed using the same operating conditions applied and checked as in BCR sequential extraction fractionation using certified reference material BCR‐701 and the standard method of addition (recoveries 96%–102%). Atomic absorption spectrometry was used to test extractable Co, Cu, and Zn contents obtained by the comparative method. Using compromised microwave conditions steps 1–3 of the sequential extraction (excluding hydrogen peroxide digestion in step 3) could be accomplished with an ultrasonic bath between 15 and 30 min, whereas 60–120 s were needed for microwave single‐extraction (MSE). The total concentrations of Co, Cu, and Zn extractable metals produced by three separate extractions ranged from 1.02–3.30, 5.02–9.95, and 3.97–8.01 μg/g respectively. Consequently, the use of single‐step extraction with the aid of microwave and ultrasound energy to reduce the time required for single‐step extraction based on the BCR sequential extraction method. However, with the aid of developed single‐step extraction methods, the obtained results were comparable to those values obtained from BCR sequential extraction method. For further study, the MSE can be frequently used to know the metal‐bound intensity with a different chemical fraction on environmental solid samples.
Characteristics of gas‐production, electricity‐generation, and anode biofilm microorganisms based on electrochemical anaerobic digestion of different substrates
Authors: Long Xiangang , Wang Huabin , Yang Sixia , Xu Kunde , Liu Haibo , Wang Nan , Liu Hongzhou , Li Jianchang 
Published: January 2021

AbstractIn this article, it intends to find out the dominant strains on the anode biofilm that prominently contribute to the improvement of biogas quality and methane (CH4) conversion, the relationships between the gas‐producing potential, electricity‐generating capacity, and anode biofilm microbial characteristics were investigated by using volatile fatty acids (intermediates of AD) and glucose as substrates. The experimental results showed that the gas‐producing potential and electricity‐generating capacity of EAD systems both are acetate > butyrate > propionate > glucose. The acetate experimental group had better gas‐producing potential and higher content of hydrogen and methane accounting for 16.12 and 82.61%, respectively. The electrochemical activity of anodic biofilms has been proved to be positively correlated with the electricity‐generating capacity of different substrates, and the acetate experimental group had a greater electricity‐generating capacity with a peak current of 23.07 mA and a coulombic efficiency of 57.69%. The more remarkable gas‐producing potential and electricity‐generating capacity of the experimental group are, and the larger quantities of electroactive microorganisms on the anode biofilm is, there are two strains commonly shared by four different substrate anode biofilms that contribute the most to improve biogas quality and CH4 yield, namely F. Clostridium Perfringens with a hydrogen‐producing ability and P. Geobacter Lovleyi with a power‐generating capacity. All results concerned above will contribute to enormously improve the CH4 conversion rate and the biogas quality. Moreover, these electroactive microorganisms also have very broad application prospects in terms of organic sewage treatment and kitchen waste treatment.
Synthesis of t‐B.PWFe/NiO nanocomposite as an efficient and heterogeneous green nanocatalyst for catalytic oxidative‐extractive desulfurization of gasoline
Authors: Rezvani Mohammad A. , Aghmasheh Masomeh 
Published: January 2021

AbstractThis study aimed to improve the efficiency of sulfur removal from real and model liquid fuel, which is still a challenge. The heterogeneous nanocatalyst was synthesized successfully by supporting ([n‐C4H9]4N)4H[PW11FeO39] (t‐B.PWFe), on nickel oxide (NiO) as a new nanocomposite (t‐B.PWFe/NiO) via sol–gel method. The catalytic activity of the nanocomposite was evaluated for oxidative–extractive desulfurization (OEDS) of model fuel and real gasoline using CH3COOH/H2O2 as an oxidant. The synthesized nanocatalyst was characterized by means of X‐ray diffraction, scanning electron microscopy, Fourier transform infrared, ultraviolet–visible spectroscopy (UV–Vis), and cyclic voltammetry. From UV–Vis, the bandgap energy is found. After OEDS treatments, the obtained results were specified that mercaptans and total sulfur content of real gasoline lowered with about 97% yield. Mechanisms, kinetic studies, and the effect of various operational parameters were evaluated, such as temperature and time on the oxidation reaction. The unique performance of the t‐B.PWFe/NiO proved the extreme capability of this system for sulfur removal to achieve purified and clean gasoline.
Optimal design of inerter‐based nonpacked particle damper considering particle rolling
Authors: Huang Xuhong , Li Xiaojun , Wang Jin 
Published: January 2021

AbstractThis paper presents an optimal design method for a nonpacked particle damper (NPPD) based on a simplified mechanical model and corresponding damping mechanism analysis. First, an equivalent inertial single‐particle mechanics model (EISM) and the corresponding equivalent principle were proposed to consider the influence of particle rolling on the vibration reduction. The experimental verification of the EISM under seismic ground motion was subsequently carried out. Based on a reasonable verification of the proposed model, an analytical solution of the EISM single‐degree‐of‐freedom structure system for the symmetric two‐impacts‐per‐cycle motion was obtained. The influence analyses of collision distance on the damping effect and the damping mechanism under resonance and nonresonance harmonic excitation were performed. The theoretical calculation formula for the optimal collision distance for energy consumption was obtained based on the damping mechanism analysis. Finally, numerical simulations under harmonic excitation and seismic ground motion were carried out to verify the rationality and generalization of the proposed optimal collision distance. Accordingly, an optimal design method for the NPPD was proposed. Based on the proposed optimization method, the vibration reduction effect of NPPD under far‐field records, near‐fault pulse‐like records, and near‐fault nonpulse records are discussed. The analysis results show that the vibration reduction effect of the NPPD is affected by the response frequency of the uncontrolled structure. The proposed optimization method can be used as the basis for the optimization of NPPD under earthquakes.
Multiple‐input multiple‐output system design of multidimensional orthogonal frequency division multiplexing system with coded direct index modulation
Authors: An Changyoung , Ryu Heung‐Gyoon 
Published: January 2021

AbstractIn this paper, two kinds of design methods of combining the multidimensional (MD) orthogonal frequency division multiplexing (OFDM) with coded direct index modulation (CDIM) system and multiple‐input multiple‐output (MIMO) technology are proposed to increase the spectrum efficiency more. These systems can be called as dimension‐dependent system and dimension‐independent system, respectively. MD‐OFDM‐CDIM was proposed to overcome the limitations of the spectral efficiency of MD‐OFDM. It has some advantages in terms of spectral efficiency and the performance is comparable to OFDM. However, there is a lack of compatibility studies with MIMO to increase the spectral efficiency. Therefore, in this paper, the compatibility of MD‐OFDM‐CDIM with MIMO is shown and the performance of the combined MIMO MD‐OFDM‐CDIM systems is evaluated. The simulation results show that the performance of the two proposed systems are similar under the conditions for the same spectral efficiency. However, the dimension‐independent system is better than the dimension‐dependent system because the reception processing complexity of the dimension‐dependent system increases significantly as the numbers of transmission and reception antennas go to higher.