bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of E-Commerce Adoption on Farmers’ Participation in the Digital Financial Market: Evidence from Rural China
Authors: Su Lanlan , Peng Yanling , Kong Rong , Chen Qiu
Published: April 2021

Although the increasing adoption of digital finance in recent years has exerted a wide-ranging influence on farmers’ consumption and production activities, many farmers in China still seriously suffer from digital financial exclusion. Few studies have documented the different impacts of e-commerce adoption characterized by online purchases and sales on farmers’ participation in the digital financial market measured by their engagement in digital payments, digital wealth management, and digital credit in rural China. Using survey data from 832 entrepreneurial households in rural China, we contribute to the literature by confirming that both online purchases and sales have a robust significant and positive impact on farmers’ participation in the digital financial market and that this impact on digital wealth management is successively larger than that on digital payments and digital credit, with the propensity score matching (PSM) method and instrument variable (IV) approach employed. We further discover that the impact of online purchases and sales on farmers’ participation in the digital financial market is significantly mediated by digital financial literacy. Moreover, the impact of online purchases and sales on farmers’ participation in the digital financial market is larger for those with high education levels, pursuing skills training, running new agricultural operation entities (i.e., family farms, professional cooperatives), and engaging in agricultural entrepreneurship. Our findings suggest that more effective measures to enhance adoption rates of online purchases and sales, innovation in rural market-oriented digital financial products and services, systematic training for farmers in e-commerce skills as well as digital financial literacy, and differentiated support measures for different groups of farmers to reduce the gap are urgently needed in China.
Discourse and Form Constraints on Licensing Object-First Sentences in German
Authors: Bader Markus , Portele Yvonne
Published: April 2021

In German, the subject usually precedes the object (SO order), but, under certain discourse conditions, the object is allowed to precede the subject (OS order). This paper focuses on main clauses in which either the subject or a discourse-given object occurs in clause-initial position. Two acceptability experiments show that OS sentences with a given object are generally acceptable, but the precise degree of acceptability varies both with the object‘s referential form (demonstrative objects leading to higher acceptability than other types of objects) and with formal properties of the subject (pronominal subjects leading to higher acceptability than non-pronominal subjects). For SO sentences, acceptability was reduced when the object was a d-pronoun, which contrasts with the high acceptability of OS sentences with a d-pronoun object. This finding was explored in a third acceptability experiment comparing d-pronouns in subject and object function. This experiment provides evidence that a reduction in acceptability due to a prescriptive bias against d-pronouns is suspended when the d-pronoun occurs as object in the prefield. We discuss the experimental results with respect to theories of German clause structure that claim that OS sentences with different information-structural properties are derived by different types of movement.
Minimum Radiant Exposure and Irradiance for Triggering Adequate Polymerization of a Photo-Polymerized Resin Cement
Authors: Li Qi , Lin Hong-Lei , Zheng Ming , Ozcan Mutlu , Yu Hao
Published: April 2021

This study aimed to establish the minimum radiant exposure and irradiance to trigger an adequate polymerization of a photo-polymerized resin cement. In total, 220 disc-shaped specimens (diameter of 10 mm and thickness of 0.1 mm) were fabricated using a photo-polymerized resin cement (Variolink N-transparent, Ivoclar Vivadent). To investigate the minimum radiant exposure, the specimens were polymerized with radiant exposures of 1, 2, 3, 4, 5, 6, and 18 J/cm2 (n = 20). During polymerization, the irradiance was maintained at 200 mW/cm2. To investigate the minimum irradiance, the specimens were polymerized with irradiances of 50, 100, 150, and 200 mW/cm2 (n = 20). During polymerization, the radiant exposure was maintained at the previously determined minimum radiant exposure. The Vickers microhardness (HV) and degree of conversion (DC) of the carbon double bond of the specimens were measured to determine the degree of polymerization of the specimens. The results were analyzed using one-way analysis of variance (ANOVA) and Tukey’s test (p < 0.05). In the investigation of the minimum radiant exposure, the HV and DC of the specimens polymerized with a radiant exposure from 1 to 5 J/cm2 were significantly lower than those with 18 J/cm2 (all p < 0.05). However, no significant difference in HV and DC was found between the specimens polymerized with 6 J/cm2 and 18 J/cm2 (p > 0.05). In the investigation of the minimum irradiance, the specimens polymerized with an irradiance of 50 mW/cm2 had significantly lower HV and DC than the specimens polymerized with an irradiance of 200 mW/cm2 (p < 0.05). However, no significant difference in the HV and DC was found among the specimens cured with irradiances of 100, 150, and 200 mW/cm2 (p > 0.05). In conclusion, the minimum radiant exposure and irradiance to trigger an adequate polymerization of the light-cured resin cement were 6 J/cm2 and 100 mW/cm2, respectively.
Preparation of CD3 Antibody-Conjugated, Graphene Oxide Coated Iron Nitride Magnetic Beads and Its Preliminary Application in T Cell Separation
Authors: Liang Tianya , Li Jianxing , Liu Xiao , Ma Zhuang , Su Xiaojin , Meng Xiangjiao , Zhanghuang Ziyi , Wang Huiqin , Li Jintao , Wang Qun , Wang Minglian
Published: April 2021

Immunomagnetic beads (IMBs) for cell sorting are universally used in medical and biological fields. At present, the IMBs on the market are ferrite coated with a silicon shell. Based on a new type of magnetic material, the graphene coated iron nitride magnetic particle (G@FeN-MP), which we previously reported, we prepared a novel IMB, a graphene oxide coated iron nitride immune magnetic bead (GO@FeN-IMBs), and explored its feasibility for cell sorting. First, the surface of the G@FeN-MP was oxidized to produce oxygen-containing groups as carboxyl, etc. by the optimized Hummers’ method, followed by a homogenization procedure to make the particles uniform in size and dispersive. The carboxy groups generated were then condensed and coupled with anti-CD3 antibodies by the carbodiimide method to produce an anti-CD3-GO@FeN-IMB after the coupling efficacy was proved by bovine serum albumin (BSA) and labeled antibodies. Finally, the anti-CD3-GO@FeN-IMBs were incubated with a cell mixture containing human T cells. With the aid of a magnetic stand, the T cells were successfully isolated from the cell mixture. The isolated T cells turned out to be intact and could proliferate with the activation of the IMBs. The results show that the G@FeN-MP can be modified for IMB preparation, and the anti-CD3-GO@FeN-IMBs we prepared can potentially separate T cells.
Learning Neural Representations and Local Embedding for Nonlinear Dimensionality Reduction Mapping
Authors: Wu Sheng-Shiung , Jong Sing-Jie , Hu Kai , Wu Jiann-Ming
Published: April 2021

This work explores neural approximation for nonlinear dimensionality reduction mapping based on internal representations of graph-organized regular data supports. Given training observations are assumed as a sample from a high-dimensional space with an embedding low-dimensional manifold. An approximating function consisting of adaptable built-in parameters is optimized subject to given training observations by the proposed learning process, and verified for transformation of novel testing observations to images in the low-dimensional output space. Optimized internal representations sketch graph-organized supports of distributed data clusters and their representative images in the output space. On the basis, the approximating function is able to operate for testing without reserving original massive training observations. The neural approximating model contains multiple modules. Each activates a non-zero output for mapping in response to an input inside its correspondent local support. Graph-organized data supports have lateral interconnections for representing neighboring relations, inferring the minimal path between centroids of any two data supports, and proposing distance constraints for mapping all centroids to images in the output space. Following the distance-preserving principle, this work proposes Levenberg-Marquardt learning for optimizing images of centroids in the output space subject to given distance constraints, and further develops local embedding constraints for mapping during execution phase. Numerical simulations show the proposed neural approximation effective and reliable for nonlinear dimensionality reduction mapping.
A Peptides Prediction Methodology for Tertiary Structure Based on Simulated Annealing
Authors: Sánchez-Hernández Juan P. , Frausto-Solís Juan , González-Barbosa Juan J. , Soto-Monterrubio Diego A. , Maldonado-Nava Fanny G. , Castilla-Valdez Guadalupe
Published: April 2021

The Protein Folding Problem (PFP) is a big challenge that has remained unsolved for more than fifty years. This problem consists of obtaining the tertiary structure or Native Structure (NS) of a protein knowing its amino acid sequence. The computational methodologies applied to this problem are classified into two groups, known as Template-Based Modeling (TBM) and ab initio models. In the latter methodology, only information from the primary structure of the target protein is used. In the literature, Hybrid Simulated Annealing (HSA) algorithms are among the best ab initio algorithms for PFP; Golden Ratio Simulated Annealing (GRSA) is a PFP family of these algorithms designed for peptides. Moreover, for the algorithms designed with TBM, they use information from a target protein’s primary structure and information from similar or analog proteins. This paper presents GRSA-SSP methodology that implements a secondary structure prediction to build an initial model and refine it with HSA algorithms. Additionally, we compare the performance of the GRSAX-SSP algorithms versus its corresponding GRSAX. Finally, our best algorithm GRSAX-SSP is compared with PEP-FOLD3, I-TASSER, QUARK, and Rosetta, showing that it competes in small peptides except when predicting the largest peptides.
Optimising the DPPH Assay for Cell-Free Marine Microorganism Supernatants
Authors: Gang Yehui , Eom Tae-Yang , Marasinghe Svini Dileepa , Lee Youngdeuk , Jo Eunyoung , Oh Chulhong
Published: April 2021

Antioxidants prevent ageing and are usually quantified and screened using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. However, this assay cannot be used for salt-containing samples, such as the cell-free supernatants of marine microorganisms that are aggregated under these conditions. Herein, the DPPH solvent (methanol or ethanol) and its water content were optimized to enable the analysis of salt-containing samples, aggregation was observed for alcohol contents of >70%. The water content of methanol influenced the activities of standard antioxidants but did not significantly affect that of the samples. Based on solution stability considerations, 70% aqueous methanol was chosen as the optimal DPPH solvent. The developed method was successfully applied to the cell-free supernatants of marine bacteria (Pseudoalteromonas rubra and Pseudoalteromonas xiamenensis), revealing their high antioxidant activities. Furthermore, it was concluded that this method would be useful for the screening of marine microorganism–derived antioxidants, which also has numerous potential applications, such as salt-fermented foods.
Knowledge, Attitudes, Practices and Some Characteristic Features of People Recovered from COVID-19 in Turkey
Authors: Yakut Seda , Karagülle Burcu , Atçalı Tuğçe , Öztürk Yasin , Açık Mehmet Nuri , Çetinkaya Burhan
Published: April 2021

Background and objectives: The whole world is spending an extraordinary effort by implementing various measures to control and prevent the COVID-19 pandemic. The effectiveness of the preventive measures is greatly influenced by the public’s knowledge, attitudes, and practices (KAP) towards the disease. In this study, KAP values and some characteristic features of people recovered from COVID-19 were determined by conducting a questionnaire survey. Materials and Methods: The questionnaire survey was conducted between 1 and 10 January 2021 on people who recovered from COVID-19 in a total of 150 different locations in Turkey. The questionnaire consisted of 46 questions: 14 for determining demographic and some characteristic features of the participants, and 32 for determining their knowledge, attitudes, and practices. The data obtained were evaluated using descriptive statistics, chi-squared tests, t-tests, and one-way analysis of variance (ANOVA). Results: It was determined that 63% of the participants had at least one chronic illness, 3.9% suffered from the disease twice, and 45.2% changed their smoking habits. The average knowledge score of the participants about COVID-19 was calculated as 10.25 (SD = 2.37; range 0–15). The participants were found to have a high level of knowledge about the symptoms and prevention methods in general, and positive changes in post-illness attitudes and behaviors. However, there was a great instability regarding the drugs and vaccines used in the treatment of COVID-19. Conclusions: This was the first study carried out in Turkey to determine knowledge, attitudes, practices, and some characteristic features of people who recovered from COVID-19. It was suggested that health authorities in the country need to develop more effective strategies and policies to find out permanent solutions in order to control and prevent the COVID-19 pandemic by taking into account the concerns of the public, particularly with regards to the drugs used in the treatment and vaccination.
Porcine Xenograft and Epidermal Fully Synthetic Skin Substitutes in the Treatment of Partial-Thickness Burns: A Literature Review
Authors: Haller Herbert L. , Blome-Eberwein Sigrid E. , Branski Ludwik K. , Carson Joshua S. , Crombie Roselle E. , Hickerson William L. , Kamolz Lars Peter , King Booker T. , Nischwitz Sebastian P. , Popp Daniel , Shupp Jeffrey W. , Wolf Steven E.
Published: April 2021

Background and Objectives: Porcine xenografts have been used successfully in partial thickness burn treatment for many years. Their disappearance from the market led to the search for effective and efficient alternatives. In this article, we examine the synthetic epidermal skin substitute Suprathel® as a substitute in the treatment of partial thickness burns. Materials and Methods: A systematic review following the PRISMA guidelines has been performed. Sixteen Suprathel® and 12 porcine xenograft studies could be included. Advantages and disadvantages between the treatments and the studies’ primary endpoints have been investigated qualitatively and quantitatively. Results: Although Suprathel had a nearly six times larger TBSA in their studies (p < 0.001), it showed a significantly lower necessity for skin grafts (p < 0.001), and we found a significantly lower infection rate (p < 0.001) than in Porcine Xenografts. Nonetheless, no significant differences in the healing time (p = 0.67) and the number of dressing changes until complete wound healing (p = 0.139) could be found. Both products reduced pain to various degrees with the impression of a better performance of Suprathel® on a qualitative level. Porcine xenograft was not recommended for donor sites or coverage of sheet-transplanted keratinocytes, while Suprathel® was used successfully in both indications. Conclusion: The investigated parameters indicate that Suprathel® to be an effective replacement for porcine xenografts with even lower subsequent treatment rates. Suprathel® appears to be usable in an extended range of indications compared to porcine xenograft. Data heterogeneity limited conclusions from the results.
Efficacy of Carbamazepine and Its Derivatives in the Treatment of Bipolar Disorder
Authors: Grunze Anna , Amann Benedikt L. , Grunze Heinz
Published: April 2021

Background and Objectives: This review is dedicated to the use of carbamazepine and its derivatives oxcarbazepine and eslicarbazepine in bipolar disorder and their relative strengths in treating and preventing new depressive or manic episodes. This paper will discuss the evidence of their efficacy relative to the polarity of relapse from controlled acute and maintenance/relapse prevention studies in bipolar patients. Materials and Methods: A Medline search was conducted for controlled acute and maintenance studies with carbamazepine, oxcarbazepine, and eslicarbazepine in bipolar disorder. In addition, abstracts reporting on controlled studies with these medications from key conferences were taken into consideration. Results: Information was extracted from 84 articles on the acute and prophylactic efficacy of the medications under consideration. They all appear to have stronger efficacy in treating acute mania than depression, which also translates to better protection against manic than depressive relapses for carbamazepine. Still, there is a paucity of controlled acute studies on bipolar depression for all and, with the exception of carbamazepine, a lack of long-term monotherapy maintenance data. For eslicarbazepine, the efficacy in bipolar disorder remains largely unknown. Especially with carbamazepine, tolerability issues and drug–drug interactions need to be kept in mind. Conclusions: Two of the medications discussed in this review, carbamazepine and oxcarbazepine, match Class A criteria according to the criteria proposed by Ketter and Calabrese, meaning acute antimanic efficacy, prevention of manic relapses, and not causing or worsening depression.
The Management of Immunosuppression in Kidney Transplant Recipients with COVID-19 Disease: An Update and Systematic Review of the Literature
Authors: Angelico Roberta , Blasi Francesca , Manzia Tommaso Maria , Toti Luca , Tisone Giuseppe , Cacciola Roberto
Published: April 2021

Background and Objectives: In the era of the coronavirus disease 2019 (COVID-19) pandemic, the management of immunosuppressive (IS) therapy in kidney transplant (KT) recipients affected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) requires attention. It is not yet understood whether IS therapy may protect from the cytokine storm induced by SARS-CoV-2 infection or a temporary adjustment/withdrawal of IS therapy to restore the immune system may be necessary. We performed a systematic literature review to investigate the current management of IS therapy in KT recipients with COVID-1. Materials and Methods: Out of 71 articles published from 1 February 2020 until 30 October 2020, 554 KT recipients with SARS-CoV-2 infection were identified. Results: Modifications of IS therapy were based on the clinical conditions. For asymptomatic patients or those with mild COVID-19 symptoms, a “wait and see approach” was mostly used; a suspension of antimetabolites drugs (347/461, 75.27%) or mTOR inhibitors (38/48, 79.2%) was adopted in the majority of patients with symptomatic COVID-19 infections. For CNIs, the most frequent attitude was their maintenance (243/502, 48.4%) or dose-reduction (99/502, 19.72%) in patients asymptomatic or with mild COVID-19 symptoms, while drug withdrawal was the preferred choice in severely symptomatic patients (160/450, 31.87%). A discontinuation of all IS drugs was used only in severely symptomatic COVID-19 patients on invasive mechanical ventilation. Renal function remained stable in 422(76.17%) recipients, while 49(8.84%) patients experienced graft loss. Eight (1.44%) patients experienced a worsening of renal function. The overall mortality was 21.84%, and 53(9.56%) patients died with functioning grafts. Conclusion: A tailored approach to the patient has been the preferred strategy for the management of IS therapy in KT recipients, taking into account the clinical conditions of patients and the potential interactions between IS and antiviral drugs, in the attempt to balance the risks of COVID-19-related complications and those due to rejection or graft loss.
Fabrication of Porous SiC by Direct Selective Laser Sintering Effect of Boron Carbide
Authors: Liu Rongzhen , Chen Gong , Qiu Yudi , Chen Peng , Shi Yusheng , Yan Chunze , Tan Hongbin
Published: April 2021

Additive manufactured porous SiC is a promising material applied in extreme conditions characterised by high temperatures, chemical corrosion, and irradiation etc. However, residual Si’s existence deteriorates its performance and limits its application in harsh environments. In this study, B4C was introduced into the selective laser sintering process of SiC, and its effects on forming ability, pore parameters, microstructure, and phases were investigated. The results showed that when B4C was added, the processing window was enlarged. The minimum energy density was reduced from 457 J/cm2 to 214 J/cm2 when the content of B4C reached 15 wt%. Microstructure orientation was enhanced, and the residual silicon content was decreased from 38 at.% to about 8 at.%. Small pores were turned into large pores with the increase of B4C addition. The findings indicate that the addition of B4C increases the amount of liquid phase during the laser sintering process of silicon carbide, improving the SiC struts’ density and reducing the residual silicon by reacting with it. Therefore, the addition of B4C will help improve the application performance of selected laser-sintered silicon carbide under extreme conditions.
Data Processing Optimization in Untargeted Metabolomics of Urine Using Voigt Lineshape Model Non-Linear Regression Analysis
Authors: Haslauer Kristina E. , Schmitt-Kopplin Philippe , Heinzmann Silke S.
Published: April 2021

Nuclear magnetic resonance (NMR) spectroscopy is well-established to address questions in large-scale untargeted metabolomics. Although several approaches in data processing and analysis are available, significant issues remain. NMR spectroscopy of urine generates information-rich but complex spectra in which signals often overlap. Furthermore, slight changes in pH and salt concentrations cause peak shifting, which introduces, in combination with baseline irregularities, un-informative noise in statistical analysis. Within this work, a straight-forward data processing tool addresses these problems by applying a non-linear curve fitting model based on Voigt function line shape and integration of the underlying peak areas. This method allows a rapid untargeted analysis of urine metabolomics datasets without relying on time-consuming 2D-spectra based deconvolution or information from spectral libraries. The approach is validated with spiking experiments and tested on a human urine 1H dataset compared to conventionally used methods and aims to facilitate metabolomics data analysis.
High Rates of Liver Cirrhosis and Hepatocellular Carcinoma in Chronic Hepatitis B Patients with Metabolic and Cardiovascular Comorbidities
Authors: Bockmann Jan-Hendrik , Kohsar Matin , Murray John M. , Hamed Vanessa , Dandri Maura , Lüth Stefan , Lohse Ansgar W. , Schulze-zur-Wiesch Julian
Published: April 2021

Background: The prevalence of metabolic and cardiovascular diseases is rising worldwide. However, little is known about the impact of such disorders on hepatic disease progression in chronic hepatitis B (CHB) during the era of potent nucleo(s)tide analogues (NAs). Methods: We retrospectively analyzed a single-center cohort of 602 CHB patients, comparing the frequency of liver cirrhosis at baseline and incidences of liver-related events during follow-up (hepatocellular carcinoma, liver transplantation and liver-related death) between CHB patients with a history of diabetes, obesity, hypertension or coronary heart disease (CHD). Results: Rates of cirrhosis at baseline and liver-related events during follow-up (median follow-up time: 2.51 years; NA-treated: 37%) were substantially higher in CHB patients with diabetes (11/23; 3/23), obesity (6/13; 2/13), CHD (7/11; 2/11) or hypertension (15/43; 4/43) compared to CHB patients without the indicated comorbidities (26/509; 6/509). Multivariate analysis identified diabetes as the most significant predictor for cirrhosis (p = 0.0105), while comorbidities did not correlate with liver-related events in pre-existing cirrhosis. Conclusion: The combination of metabolic diseases and CHB is associated with substantially increased rates of liver cirrhosis and secondary liver-related events compared to CHB alone, indicating that hepatitis B patients with metabolic comorbidities warrant particular attention in disease surveillance and evaluation of treatment indication.
Limonin Enhances the Antifungal Activity of Eugenol Nanoemulsion against Penicillium Italicum In Vitro and In Vivo Tests
Authors: Li Yi , Zhao Runan , Li Yan , Zhou Zhiqin
Published: April 2021

Penicillium italicum, the cause of citrus blue mold, is a pathogenic fungus that seriously affects the postharvest quality of citrus fruit and causes serious economic loss. In this study, a eugenol nanoemulsion containing limonin, an antimicrobial component from citrus seeds, was prepared using a high-pressure microfluidizer and the antifungal activity of the nanoemulsions against P. italicum was evaluated based on the conidial germination rate, mycelial growth, and scanning electron microscopy analysis. The results showed that the minimum inhibitory concentration and the inhibition rate of limonin-loaded eugenol nanoemulsion was 160 μg/mL and 59.21%, respectively, which was more potent than that of the limonin-free eugenol emulsion. After treatment with the nanoemulsions, the integrity of the P. italicum cell membrane was disrupted, the cell morphology was abnormal, and the leakage of nucleic acid and protein was observed. In addition, the challenge test on citrus fruits revealed that the limonin-loaded eugenol emulsion inhibited citrus infection for longer periods, with an infection rate of 29.2% after 5 days. The current research shows that nanoemulsions containing limonin and eugenol have effective antifungal activity against P. italicum, and may be used as a substitute for inhibiting blue mold in citrus fruits.
A Review on the Methods Used for the Detection and Diagnosis of Rabbit Hemorrhagic Disease Virus (RHDV)
Authors: Abrantes Joana , Lopes Ana M.
Published: April 2021

Since the early 1980s, the European rabbit (Oryctolagus cuniculus) has been threatened by the rabbit hemorrhagic disease (RHD). The disease is caused by a lagovirus of the family Caliciviridae, the rabbit hemorrhagic disease virus (RHDV). The need for detection, identification and further characterization of RHDV led to the development of several diagnostic tests. Owing to the lack of an appropriate cell culture system for in vitro propagation of the virus, much of the methods involved in these tests contributed to our current knowledge on RHD and RHDV and to the development of vaccines to contain the disease. Here, we provide a comprehensive review of the RHDV diagnostic tests used since the first RHD outbreak and that include molecular, histological and serological techniques, ranging from simpler tests initially used, such as the hemagglutination test, to the more recent and sophisticated high-throughput sequencing, along with an overview of their potential and their limitations.
Lactobacillus crispatus BC1 Biosurfactant Counteracts the Infectivity of Chlamydia trachomatis Elementary Bodies
Authors: Foschi Claudio , Parolin Carola , Giordani Barbara , Morselli Sara , Luppi Barbara , Vitali Beatrice , Marangoni Antonella
Published: April 2021

Lactobacilli-derived biosurfactants (BS) have shown promising effects as antimicrobial molecules. Since Lactobacillus crispatus plays a crucial role in maintaining vaginal eubiosis, BS from this species could represent novel therapeutic agents to counteract sexually transmitted pathogens, such as Chlamydia trachomatis (CT). The aim of the present study was to assess the inhibitory effects of a BS produced by the vaginal strain L. crispatus BC1 on the infectivity of CT elementary bodies (EBs). For concentrations ranging between 1 and 0.5 mg/mL at 60-min contact time, L. crispatus BC1 BS displayed a highly significant anti-CT activity, with about 50% reduction of EB infectivity towards HeLa cells. To identify the components responsible for chlamydial inhibition, a panel of selected fatty acids, including those present in BS lipopeptidic structure, was tested against CT EBs. Pentadecanoic acid, myristic acid, β-hydroxy-myristic acid, and β-hydroxy-palmitic acid were able to significantly reduce EBs infectivity up to 5–0.5 µg/mL, concentrations that resulted to be non-toxic for HeLa cells. These data can contribute to the understanding of the biological role of lactobacilli in the vaginal niche, as well as to promote the application of their produced BS as an innovative and antibiotic-sparing anti-chlamydial strategy.
Extracellular Polymeric Substance Protects Some Cells in an Escherichia coli Biofilm from the Biomechanical Consequences of Treatment with Magainin 2
Authors: Greer Helen , Overton Kanesha , Ferguson Megan , Spain Eileen , Darling Louise , Núñez Megan , Volle Catherine
Published: April 2021

Bacterial biofilms have long been recognized as a source of persistent infections and industrial contamination with their intransigence generally attributed to their protective layer of extracellular polymeric substances (EPS). EPS, consisting of secreted nucleic acids, proteins, and polysaccharides, make it difficult to fully eliminate biofilms by conventional chemical or physical means. Since most bacteria are capable of forming biofilms, understanding how biofilms respond to new antibiotic compounds and components of the immune system has important ramifications. Antimicrobial peptides (AMPs) are both potential novel antibiotic compounds and part of the immune response in many different organisms. Here, we use atomic force microscopy to investigate the biomechanical changes that occur in individual cells when a biofilm is exposed to the AMP magainin 2 (MAG2), which acts by permeabilizing bacterial membranes. While MAG2 is able to prevent biofilm initiation, cells in an established biofilm can withstand exposure to high concentrations of MAG2. Treated cells in the biofilm are classified into two distinct populations after treatment: one population of cells is indistinguishable from untreated cells, maintaining cellular turgor pressure and a smooth outer surface, and the second population of cells are softer than untreated cells and have a rough outer surface after treatment. Notably, the latter population is similar to planktonic cells treated with MAG2. The EPS likely reduces the local MAG2 concentration around the stiffer cells since once the EPS was enzymatically removed, all cells became softer and had rough outer surfaces. Thus, while MAG2 appears to have the same mechanism of action in biofilm cells as in planktonic ones, MAG2 cannot eradicate a biofilm unless coupled with the removal of the EPS.
Milling Studies in an Impact Crusher I: Kinetics Modelling Based on Population Balance Modelling
Authors: Chimwani Ngonidzashe , Bwalya Murray M.
Published: April 2021

A number of experiments were conducted on a laboratory batch impact crusher to investigate the effects of particle size and impeller speed on grinding rate and product size distribution. The experiments involved feeding a fixed mass of particles through a funnel into the crusher up to four times, and monitoring the grinding achieved with each pass. The duration of each pass was approximately 20 s; thus, this amounted to a total time of 1 min and 20 s of grinding for four passes. The population balance model (PBM) was then used to describe the breakage process, and its effectiveness as a tool for describing the breakage process in the vertical impact crusher is assessed. It was observed that low impeller speeds require longer crushing time to break the particles significantly whilst for higher speeds, longer crushing time is not desirable as grinding rate sharply decreases as the crushing time increases, hence the process becomes inefficient. Results also showed that larger particle sizes require shorter breakage time whilst smaller feed particles require longer breakage time.
The Treatment of Acid Mine Drainage Using Vertically Flowing Wetland: Insights into the Fate of Chemical Species
Authors: Nguegang Beauclair , Masindi Vhahangwele , Msagati Titus Alfred Makudali , Tekere Memory
Published: April 2021

In this study, the treatment of acid mine drainage (AMD) using vertically flowing wetland was explored. The wetland was enriched with Vetiveria zizanioides as a decontaminating media and soil as the substrate. Water was percolated through the substrate and the throughput samples were collected and characterized every five days for a period of 30 days. The obtained results revealed a tolerant index of 1.03 for Vetiveria zizanioides, and a net reduction of metals and sulfate. The removal efficacy of chemical species was observed to obey the following order: Fe (71.25%) > Zn (70.40%) > Mn (62%) > Al (56.68%)> SO42− (55.18%) > Ni (35%) > Cu (18.83%). The removal of chemical species was further aided by the used substrate, and this could be attributed to the accumulation of chemical species on the soil through precipitation, adsorption, and phyto-retention. As such, it could be deduced that the substrate plays a significant role in the removal of metals, while the grass and external factors accounted for the rest of the chemical species attenuation. The translocation assessment revealed that the distribution of chemical species was observed to be predominant in the roots, except manganese, which was transferred in the shoot (67%). The XRF, XRD, FTIR, and SEM-EDS analysis revealed the presence of AMD chemical species in the substrate and the grass components, hence confirming that the plants are playing a huge role in the removal of contaminants from AMD. The PH REdox EQuilibrium (in C language) (PHREEQC) geochemical model confirm that metals existed as di-and-trivalent complexes in AMD. Lastly, available metals were precipitated as metals hydroxides and oxy-hydrosulfates by the substrate. In light of the obtained results, vertically flowing wetland could be used for the passive treatment of AMD, and it will play a huge role in active and abandoned mines. However, prolonged assessment should be undertaken to understand its performance over a notable period of time.
Clay Mineralogy: A Signature of Granitic Geothermal Reservoirs of the Central Upper Rhine Graben
Authors: Glaas Carole , Patrier Patricia , Vidal Jeanne , Beaufort Daniel , Genter Albert
Published: April 2021

Clay minerals are the signature of hydrothermal alterations related to fluid circulation in volcanic and crystalline rocks. In the French part of the Upper Rhine Graben, in the deep-seated granites, illitic minerals (illite and I/S mixed layers (ml)) are typical products of the structurally-controlled argillic alteration in the Paleozoic granitic basement. In the new Illkirch geothermal well, GIL-1, drill-cuttings were studied with various petrographic methods to determine the characteristics of illite in paleo- and present-permeable zones, and to compare the alteration mineralogy with that of geothermal Soultz-sous-Forêts and Rittershoffen sites. Alteration petrography, crystal structure as well as the chemical composition of the illitic minerals and the altered bulk rocks were performed all along the well. This complete characterization, combined with geophysical logs and structural results, highlighted that the illitic minerals at Illkirch, Soultz-sous-Forêts, and Rittershoffen are composed of illite and illite-rich illite-smectite mixed layers (I/S ml) (<10% smectite). Two mineralogical assemblages were distinguished: chlorite + illite resulting from the propylitic alteration after the emplacement of the granitic basement under temperatures higher than 350 °C, and illite + I/S ml + carbonates + quartz resulting from the argillic alteration due to fluid circulation in the fractures at temperatures between 130 and 160 °C. Fracture zones are characterized by the occurrence of illitic minerals (illite and I/S ml), and specifically, by higher quantities of I/S ml in present-day permeable zones than in paleo-permeable zones. A conceptual model of the fracture zones at the interface between the overlying sedimentary rocks and the granitic basement is proposed. The present-day permeability distribution is controlled by the fault and fracture network, which consists of sealed zones and unsealed zones. Fluid convection in the URG implies paleo and present fluids circulating in both fractured sedimentary and crystalline reservoirs. Such circulations develop illitic minerals that could be considered as exploration guides for future geothermal sites in the URG. At Illkirch, the repartition of the present-permeable fracture zones (KFZs) in the GIL-1 well indicates that the moderately argillically altered granite distally situated from the Eschau fault is more permeable than the intensely argillically altered granite close to the Eschau fault.
Investigation the Effects of Green-Synthesized Copper Nanoparticles on the Performance of Activated Carbon-Chitosan-Alginate for the Removal of Cr(VI) from Aqueous Solution
Authors: Ahmed Inas A. , Hussein Hala S. , Ragab Ahmed H. , AlMasoud Najla , Ghfar Ayman A.
Published: April 2021

In the present investigation, green nano-zerovalent copper (GnZVCu), activated carbon (AC), chitosan (CS) and alginate (ALG) nanocomposites were produced and used for the elimination of chromium (VI) from a polluted solution. The nanocomposites GnZVCu/AC-CS-alginate and AC-CS-alginate were prepared. Analysis and characterization were performed by the following techniques: X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. The SEM analysis revealed that the nanocomposites are extremely mesoporous, which leads to the greatest adsorption of Cr+6 (i.e., 97.5% and 95%) for GnZVCu/AC-CS-alginate and AC-CS-alginate, respectively. The adsorption efficiency was enhanced by coupling GnZVCu with AC-CS-alginate with a contact time of 40 min. The maximum elimination of Cr+6 with the two nanocomposites was achieved at pH 2. The isotherm model, Freundlich adsorption isotherm and kinetics model and P.S.O.R kinetic models were discovered to be better suited to describe the exclusion of Cr+6 by the nanocomposites. The results suggested that the synthesized nanocomposites are promising for the segregation of Cr+6 from polluted solutions, specially the GnZVCu/AC-CS-alginate nanocomposite.
D936Y and Other Mutations in the Fusion Core of the SARS-CoV-2 Spike Protein Heptad Repeat 1: Frequency, Geographical Distribution, and Structural Effect
Authors: Oliva Romina , Shaikh Abdul Rajjak , Petta Andrea , Vangone Anna , Cavallo Luigi
Published: April 2021

The crown of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is constituted by its spike (S) glycoprotein. S protein mediates the SARS-CoV-2 entry into the host cells. The “fusion core” of the heptad repeat 1 (HR1) on S plays a crucial role in the virus infectivity, as it is part of a key membrane fusion architecture. While SARS-CoV-2 was becoming a global threat, scientists have been accumulating data on the virus at an impressive pace, both in terms of genomic sequences and of three-dimensional structures. On 15 February 2021, from the SARS-CoV-2 genomic sequences in the GISAID resource, we collected 415,673 complete S protein sequences and identified all the mutations occurring in the HR1 fusion core. This is a 21-residue segment, which, in the post-fusion conformation of the protein, gives many strong interactions with the heptad repeat 2, bringing viral and cellular membranes in proximity for fusion. We investigated the frequency and structural effect of novel mutations accumulated over time in such a crucial region for the virus infectivity. Three mutations were quite frequent, occurring in over 0.1% of the total sequences. These were S929T, D936Y, and S949F, all in the N-terminal half of the HR1 fusion core segment and particularly spread in Europe and USA. The most frequent of them, D936Y, was present in 17% of sequences from Finland and 12% of sequences from Sweden. In the post-fusion conformation of the unmutated S protein, D936 is involved in an inter-monomer salt bridge with R1185. We investigated the effect of the D936Y mutation on the pre-fusion and post-fusion state of the protein by using molecular dynamics, showing how it especially affects the latter one.
Focal Point Evaluation of Energies for Tautomers and Isomers for 3-hydroxy-2-butenamide: Evaluation of Competing Internal Hydrogen Bonds of Types -OH…O=, -OH…N, -NH…O=, and CH…X (X=O and N)
Authors: Altun Zikri , Bleda Erdi Ata , Trindle Carl
Published: April 2021

The title compound is a small molecule with many structural variations; it can illustrate a variety of internal hydrogen bonds, among other noncovalent interactions. Here we examine structures displaying hydrogen bonding between carbonyl oxygen and hydroxyl H; between carbonyl oxygen and amino H; hydroxyl H and amino N; hydroxyl O and amino H. We also consider H-bonding in its tautomer 2-oxopropanamide. By extrapolation algorithms applied to Hartree-Fock and correlation energies as estimated in HF, MP2, and CCSD calculations using the cc-pVNZ correlation-consistent basis sets (N = 2, 3, and 4) we obtain reliable relative energies of the isomeric forms. Assuming that such energy differences may be attributed to the presence of the various types of hydrogen bonding, we attempt to infer relative strengths of types of H-bonding. The Atoms in Molecules theory of Bader and the Local Vibrational Modes analysis of Cremer and Kraka are applied to this task. Hydrogen bonds are ranked by relative strength as measured by local stretching force constants, with the stronger =O…HO- > NH…O= > -OH…N well separated from a cluster > NH…O= ≈ >NH…OH ≈ CH…O= of comparable and intermediate strength. Weaker but still significant interactions are of type CH…N which is stronger than CH…OH.
Alkaloids of the Genus Datura: Review of a Rich Resource for Natural Product Discovery
Authors: Cinelli Maris A. , Jones A. Daniel
Published: April 2021

The genus Datura (Solanaceae) contains nine species of medicinal plants that have held both curative utility and cultural significance throughout history. This genus’ particular bioactivity results from the enormous diversity of alkaloids it contains, making it a valuable study organism for many disciplines. Although Datura contains mostly tropane alkaloids (such as hyoscyamine and scopolamine), indole, beta-carboline, and pyrrolidine alkaloids have also been identified. The tools available to explore specialized metabolism in plants have undergone remarkable advances over the past couple of decades and provide renewed opportunities for discoveries of new compounds and the genetic basis for their biosynthesis. This review provides a comprehensive overview of studies on the alkaloids of Datura that focuses on three questions: How do we find and identify alkaloids? Where do alkaloids come from? What factors affect their presence and abundance? We also address pitfalls and relevant questions applicable to natural products and metabolomics researchers. With both careful perspectives and new advances in instrumentation, the pace of alkaloid discovery—from not just Datura—has the potential to accelerate dramatically in the near future.
Antioxidants and Bioactive Compounds in Licorice Root Extract Potentially Contribute to Improving Growth, Bulb Quality and Yield of Onion (Allium cepa)
Authors: Younes Nabil A. , Rahman Md. Mezanur , Wardany Ahmed A. , Dawood Mona F. A. , Mostofa Mohammad Golam , Keya Sanjida Sultana , Abdel Latef Arafat Abdel Hamed , Tran Lam-Son Phan
Published: April 2021

The increasing culinary use of onion (Alium cepa) raises pressure on the current production rate, demanding sustainable approaches for increasing its productivity worldwide. Here, we aimed to investigate the beneficial effects of licorice (Glycyrrhiza glabra) root extract (LRE) in improving growth, yield, nutritional status, and antioxidant properties of two high-yielding onion cultivars, Shandaweel and Giza 20, growing under field conditions in two consecutive years. Our results revealed that pretreatments of both onion cultivars with LRE exhibited improved growth indices (plant height and number of leaves) and yield-related features (bulb length, bulb diameter, and bulb weight) in comparison with the corresponding LRE-devoid control plants. Pretreatments with LRE also improved the nutritional and antioxidant properties of bulbs of both cultivars, which was linked to improved mineral (e.g., K+ and Ca2+) acquisition, and heightened activities of enzymatic antioxidants (e.g., superoxide dismutase, catalase, ascorbate peroxidase, glutathione peroxidase, and glutathione S-transferase) and increased levels of non-enzymatic antioxidants (e.g., ascorbic acid, reduced glutathione, phenolics, and flavonoids). LRE also elevated the contents of proline, total free amino acids, total soluble carbohydrates, and water-soluble proteins in both onion bulbs. In general, both cultivars displayed positive responses to LRE pretreatments; however, the Shandaweel cultivar performed better than the Giza 20 cultivar in terms of yield and, to some extent, bulb quality. Collectively, our findings suggest that the application of LRE as biostimulant might be an effective strategy to enhance bulb quality and ultimately the productivity of onion cultivars under field conditions.
Simultaneous Determination of As, Bi, Sb, Se, Te, Hg, Pb and Sn by Small-Sized Electrothermal Vaporization Capacitively Coupled Plasma Microtorch Optical Emission Spectrometry Using Direct Liquid Microsampling
Authors: Angyus Simion Bogdan , Levei Erika , Petreus Dorin , Etz Radu , Covaci Eniko , Moldovan Oana Teodora , Ponta Michaela , Darvasi Eugen , Frentiu Tiberiu
Published: April 2021

The simultaneous determination of chemical vapor-generating elements involving derivatization is difficult even by inductively coupled plasma optical emission spectrometry or mass spectrometry. This study proposes a new direct liquid microsampling method for the simultaneous determination of As, Bi, Se, Te, Hg, Pb, and Sn, using a fully miniaturized set-up based on electrothermal vaporization capacitively coupled plasma microtorch optical emission spectrometry. The method is cost-effective, free from non-spectral interference, and easy to run by avoiding derivatization. The method involves the vaporization of analytes from the 10 µL sample and recording of episodic spectra generated in low-power (15 W) and low-Ar consumption (150 mL min−1) plasma microtorch interfaced with low-resolution microspectrometers. Selective vaporization at 1300 °C ensured the avoidance of non-spectral effects and allowed the use of external calibration. Several spectral lines for each element even in the range 180–210 nm could be selected. Generally, this spectral range is examined with large-scale instrumentation. Even in the absence of derivatization, the obtained detection limits were low (0.02–0.75 mg kg−1) and allowed analysis of environmental samples, such as cave and river sediments. The recovery was in the range of 86–116%, and the accuracy was better than 10%. The method is of general interest and could be implemented on any miniaturized or classical laboratory spectrometric instrumentation.