bluuebunny/crossref_metadata_2025 huggingface dataset:
The Natural Course of Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis, and Mycoplasma genitalium in Pregnant and Post-Delivery Women in Pemba Island, Tanzania
Authors: Juliana Naomi C. A. , Omar Abdulla Mbaruk , Pleijster Jolein , Aftab Fahad , Uijldert Nina B. , Ali Said M. , Ouburg Sander , Sazawal Sunil , Morré Servaas A. , Deb Saikat , Ambrosino Elena
Published: May 2021

This study aimed to determine the persistence of Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), Trichomonas vaginalis (TV) and Mycoplasma genitalium (MG) infections during pregnancy and after delivery in vaginal swabs of women from Pemba Island, Tanzania. In the context of an earlier biobanking effort, vaginal swabs were collected at two timepoints during pregnancy and once post-delivery. Detection of CT, NG, TV, and MG was performed by PCR using validated detection kits in samples from 441 pregnant women aged 16–48 years old. Among those, 202 samples were matched during pregnancy and 38 at the second timepoint of the pregnancy and post-delivery CT infection persistence during pregnancy was 100% (n = 11) after an average of eight weeks, that of TV infection 82% (n = 11) after ten weeks, and that of MG infection 75% (n = 4) after ten weeks. Post-delivery (after approximately 22 weeks) infection persistence was 100% for CT (n = 1) and 20% for TV (n = 5). NG was only detected at the last collection timepoint, its persistence rate could not be determined. These results show persistence and clearance of curable infections during and after pregnancy. Analysis of biobanked samples is a valuable approach in the investigation of the natural history of curable pathogens.
Antimicrobial and Antibiofilm Activities of Weissella cibaria against Pathogens of Upper Respiratory Tract Infections
Authors: Yeu Ji-Eun , Lee Hyeon-Gyu , Park Geun-Yeong , Lee Jisun , Kang Mi-Sun
Published: May 2021

Recently discovered preventive effects of probiotics on oral health have attracted interest to their use for the prevention and treatment of various diseases. This study aimed to evaluate the antimicrobial and antibiofilm properties of Weissella cibaria against Streptococcus pyogenes, Staphylococcus aureus, S. pneumoniae, and Moraxella catarrhalis, the major pathogens of upper respiratory tract infections (URTIs). The antimicrobial activities of W. cibaria were compared with those of other oral probiotics using a competitive inhibition assay and the determination of the minimum inhibitory concentrations (MICs). In addition, a time-kill assay, spectrophotometry, and confocal laser scanning microscopy were used to confirm the antimicrobial and antibiofilm abilities of W. cibaria CMU (oraCMU) and CMS1 (oraCMS1). Both live cells and cell-free supernatants of all tested probiotics, except Streptococcus salivarius, showed excellent antimicrobial activities. All target pathogens were killed within 4 to 24 h at twice the MIC of oraCMU and oraCMS1, which showed the highest antimicrobial activities against M. catarrhalis. The antimicrobial substances that affected different target pathogens were different. Both oraCMU and oraCMS1 showed excellent abilities to inhibit biofilm formation and remove preformed biofilms. Our results suggest that the W. cibaria probiotics offer new possibilities for the prevention and treatment of bacterial URTIs.
Depositional Environment and Genesis of the Nabeba Banded Iron Formation (BIF) in the Ivindo Basement Complex, Republic of the Congo: Perspective from Whole-Rock and Magnetite Geochemistry
Authors: Gatsé Ebotehouna Chesther , Xie Yuling , Adomako-Ansah Kofi , Gourcerol Blandine , Qu Yunwei
Published: May 2021

The Nabeba high-grade iron deposit (Republic of the Congo) is hosted by banded iron formation (BIF) in the Ivindo Basement Complex, which lies in the northwestern part of the Congo Craton. The Nabeba BIF is intercalated with chlorite-sericite-quartz schist and comprises two facies (oxide and a carbonate-oxide). In this study, whole-rock and LA-ICP-MS magnetite geochemistry of the BIF was reported. Magnetite samples from both BIF facies had fairly similar trace element compositions except for the rare earth element plus yttrium (REE + Y) distribution patterns. The high V, Ni, Cr, and Mg contents of the magnetite in the Nabeba BIF could be ascribed to the involvement of external medium-high temperature hydrothermal fluids during their deposition in relatively reduced environment. The Post-Archean Australian Shale (PAAS)-normalized REY patterns of the Nabeba BIF magnetite were characterized by LREE depletion coupled with varying La and positive Eu anomalies. Processing of the information gathered from the geochemical signatures of magnetite and the whole-rock BIF suggested that the Nabeba BIF was formed by the mixing of predominantly anoxic seawater (99.9%) with 0.1% of high-temperature (>250 °C) hydrothermal vent fluids, similar to the formation mechanism of many Archean Algoma-type BIFs reported elsewhere in the world.
Development and Validation of an Online Analyzer for Particle Size Distribution in Conveyor Belts
Authors: Leiva Claudio , Acuña Claudio , Castillo Diego
Published: May 2021

Online measurement of particle size distribution in the crushing process is critical to reduce particle obstruction and to reduce energy consumption. Nevertheless, commercial systems to determine size distribution do not accurately identify large particles (20–250 mm), leading to particle obstruction, increasing energy consumption, and reducing equipment availability. To solve this problem, an online sensor prototype was designed, implemented, and validated in a copper ore plant. The sensor is based on 2D images and specific detection algorithms. The system consists of a camera (1024 p) mounted on the conveyor belt and image processing software, which improves the detection of large particle edges. The algorithms determine the geometry of each particle, from a sequence of digital photographs. For the development of the software, noise reduction algorithms were evaluated and selected, and a routine was designed to incorporate morphological mathematics (erosion, dilation, opening, lock) and segmentation algorithms (Roberts, Prewitt, Sobel, Laplacian–Gaussian, Canny, watershed, geodesic transform). The software was implemented (in MatLab Image Processing Toolbox) based on the 3D equivalent diameter (using major and minor axes, assuming an oblate spheroid). The size distribution adjusted to the Rosin Rammler function in the major axis. To test the sensor capabilities, laboratory images were used, where the results show a precision of 5% in Rosin Rambler model fitting. To validate the large particle detection algorithms, a pilot test was implemented in a large mining company in Chile. The accuracy of large particle detection was 60% to 67% depending on the crushing stage. In conclusion, it is shown that the prototype and software allow online measurement of large particle sizes, which provides useful information for screening equipment maintenance and control of crushers’ open size setting, reducing the obstruction risk and increasing operational availability.
A Mineralogical Museum as a Geotourism Attraction: A Case Study
Authors: Turner-Carrión Magner , Carrión-Mero Paúl , Turner-Salamea Israel , Morante-Carballo Fernando , Aguilar-Aguilar Maribel , Zambrano-Ruiz Kerly , Berrezueta Edgar
Published: May 2021

The Zaruma-Portovelo mining district in Ecuador, and in particular, Portovelo City, is home to the oldest mining museum in the country. This museum, named Museo Mineralógico Magner Turner (MMMT in Spanish), is a centre that reflects, through its collections, the history and culture of this territory. This work aimed to evaluate the MMMT as a possible geosite by analysing its contributions to the geomining heritage of the Zaruma-Portovelo district, and thus, to enhance it and promote its collections as a geotouristic attraction. The work involved three phases: (i) describing the museum and its surroundings; (ii) a semiquantitative evaluation of the museum using the Brilha method and a geosites assessment model (GAM); and (iii) a qualitative evaluation using the Delphi and SWOT methodologies to define strategies and proposals for museum development. The results obtained by the semiquantitative evaluation of the geosite with the Brilha method reflect high scientific (330/400), educational (380/400) and touristic (365/400) appeal. The applied GAM shows the museum as a geosite with high principal and additional value, placing it in the Z33 field of the global valuation matrix. In addition, the semiquantitative and qualitative evaluation made it possible to describe the importance of the museum and its collections in the development of the area. The study carried out qualified the museum as a mining site with an appropriate valuation, an example of ex-situ geological heritage conservation and a basis for geotourism development.
Optimization Studies on Biological Desulfurization of Sulfide Ore Using Response Surface Methodology
Authors: Tang Jiahui , Feng Yanxi , Wu Zengling , Zhang Siyuan , Sarkodie Emmanuel Konadu , Jin Huimin , Yuan Ruiling , Pan Wei , Liu Hongwei
Published: May 2021

This research aimed to optimize the experimental conditions of biodesulfurization of sulfide ore and to evaluate the flame-retardant effect after desulfurization under optimal conditions. Six experimental factors were determined: particle size of ore sample, ambient temperature, rotary speed of the shaking table, volume of bacteria liquid, concentration of leaching aid (Tween80), and pH value of acidizing ore sample. Desulfurization efficiency was used as the main characterization index of the desulfurization effect in optimization studies. Particle size of ore sample, rotary speed of the shaking table, and volume of bacteria liquid inoculated were selected as significant factors by a Plackett–Burman experiment. Modeling, optimization, and analysis of the interactive effects of these factors, notably between particle size and bacteria liquid, were performed using a Box–Behnken design with response surface methodology. The optimum operating conditions were found to be: particle size of 120 to 140 mesh, rotary speed of 175 rpm, and bacteria liquid of 111 mL. Under these conditions, a significant rise of 8.1% was seen in 5-day average desulfurization efficiency. The 5-day oxidation weight gain rate of desulfurized ore was 2.73%, while that of the control group was 4.78%. The results show that, after optimized desulfurization, the surface oxidizability and spontaneous combustion tendency of the ore are reduced.
Piperlongumine Analogs Promote A549 Cell Apoptosis through Enhancing ROS Generation
Authors: Sun Ai-Ling , Mu Wen-Wen , Li Yan-Mo , Sun Ya-Lei , Li Peng-Xiao , Liu Ren-Min , Yang Jie , Liu Guo-Yun
Published: May 2021

Chemotherapeutic agents, which contain the Michael acceptor, are potent anticancer molecules by promoting intracellular reactive oxygen species (ROS) generation. In this study, we synthesized a panel of PL (piperlongumine) analogs with chlorine attaching at C2 and an electron-withdrawing/electron-donating group attaching to the aromatic ring. The results displayed that the strong electrophilicity group at the C2–C3 double bond of PL analogs plays an important role in the cytotoxicity whereas the electric effect of substituents, which attached to the aromatic ring, partly contributed to the anticancer activity. Moreover, the protein containing sulfydryl or seleno, such as TrxR, could be irreversibly inhibited by the C2–C3 double bond of PL analogs, and boost intracellular ROS generation. Then, the ROS accumulation could disrupt the redox balance, induce lipid peroxidation, lead to the loss of MMP (Mitochondrial Membrane Potential), and ultimately result in cell cycle arrest and A549 cell line death. In conclusion, PL analogs could induce in vitro cancer apoptosis through the inhibition of TrxR and ROS accumulation.
Antitumor Activity and Potential Mechanism of Novel Fullerene Derivative Nanoparticles
Authors: Ye Lianjie , Kollie Larwubah , Liu Xing , Guo Wei , Ying Xiangxian , Zhu Jun , Yang Shengjie , Yu Meilan
Published: May 2021

The development of novel nanoparticles as a new generation therapeutic drug platform is an active field of chemistry and cancer research. In recent years, fullerene nanoparticles have received extensive attention due to their unique physical and chemical properties. Properly modified fullerene nanoparticles have excellent biocompatibility and significant anti-tumor activity, which makes them have broad application prospects in the field of cancer therapy. Therefore, understanding the anti-tumor mechanism of fullerene nanoparticles is of great significance for the design and development of anti-tumor drugs with low toxicity and high targeting. This review has focused on various anti-tumor mechanisms of fullerene derivatives and discusses their toxicity and their distribution in organisms. Finally, the review points out some urgent problems that need solution before fullerene derivatives as a new generation of anti-tumor nano-drug platform enter clinical research.
Effect of Filtrated Osmotic Solution Based on Concentrated Chokeberry Juice and Mint Extract on the Drying Kinetics, Energy Consumption and Physicochemical Properties of Dried Apples
Authors: Masztalerz Klaudia , Łyczko Jacek , Lech Krzysztof
Published: May 2021

Background: Filtration of osmotic solution affects selective penetration during osmotic dehydration (OD), and after drying is finished, this can influence the chemical composition of the material, which is also modified by OD. Methods: Osmotic dehydration was carried out in filtrated and non-filtrated concentrated chokeberry juice with the addition of mint infusion. Then, this underwent convective drying, vacuum-microwave drying and combined convective pre-drying, followed by vacuum-microwave finishing drying. Drying kinetics were presented and mathematical models were selected. The specific energy consumption for each drying method was calculated and the energy efficiency was determined. Results and Discussion: The study revealed that filtration of osmotic solution did not have significant effect on drying kinetics; however, it affected selective penetration during OD. The highest specific energy consumption was obtained for the samples treated by convective drying (CD) (around 170 kJ·g−1 fresh weight (fw)) and the lowest for the samples treated by vacuum-microwave drying (VMD) (around 30 kJ·g−1 fw), which is due to the differences in the time of drying and when these methods are applied. Conclusions: Filtration of the osmotic solution can be used to obtain the desired material after drying and the VMD method is the most appropriate considering both phenolic acid content and the energy aspect of drying.
Polyoxygenated Klysimplexane- and Eunicellin-Based Diterpenoids from the Gorgonian Briareum violaceum
Authors: Ahmed Atallah F. , Cheng Yang , Dai Chang-Feng , Sheu Jyh-Horng
Published: May 2021

Three new polyoxygenated diterpenoids with a rare 4-isopropyl-1,5,8a-trimethylperhydrophenanthrane structure of the klysimplexane skeleton, briarols A‒C (1‒3), and one eunicellin-based diterpenoid, briarol D (4), were isolated from Briareum violaceum, a gorgonian inhabiting Taiwanese waters. The chemical structures of these compounds were determined by employing extensive analyses of NMR and high-resolution electrospray ionization mass spectrometry (HRESIMS) data. Metabolites 1‒3 were found to possess the rarely found skeleton of the diterpenoid klysimplexin T. All isolated compounds showed very weak cytotoxic activity against the growth of three cancer cell lines. A plausible biosynthetic pathway for briarols A‒C from the coexisting eunicellin diterpenoid briarol D (4) was postulated.
In Vitro and In Vivo Activity of 14-O-[(4,6-Diamino-pyrimidine-2-yl) thioacetyl] Mutilin against Methicillin-Resistant Staphylococcus aureus
Authors: Fu Yunxing , Leng Chunqing , Fan Yuan , Ma Xia , Li Xianghui , Wang Xuefei , Guo Zhenghuan , Wang Xiujun , Shang Ruofeng
Published: May 2021

Staphylococcus aureus (S. aureus) is a major human pathogen that requires new antibiotics with unique mechanism. A new pleuromutilin derivative, 14-O-[(4,6-Diamino-pyrimidine-2-yl) thioacetyl] mutilin (DPTM), has been synthesized and proved as a potent antibacterial agent using in vitro and in vivo assays. In the present study, DPTM was further in vitro evaluated against methicillin-resistant Staphylococcus aureus (MRSA) isolated from dairy farms and outperformed tiamulin fumarate, a pleuromutilin drug used for veterinary. Moreover, a murine skin wound model caused by MRSA infection was established, and the healing effect of DPTM was investigated. The results showed that DPTM could promote the healing of MRSA skin infection, reduce the bacterial burden of infected skin MRSA and decrease the secretion of IL-6 and TNF-α inflammatory cytokines in plasma. These results provided the basis for further in-depth drug targeted studies of DPTM as a novel antibacterial agent.
Multiarm Star-Shaped Polydimethylsiloxanes with a Dendritic Branching Center
Authors: Tikhonov Pavel A. , Vasilenko Nataliya G. , Gallyamov Marat O. , Cherkaev Georgii V. , Vasil’ev Viktor G. , Demchenko Nina V. , Buzin Mikhail I. , Vasil’ev Sergey G. , Muzafarov Aziz M.
Published: May 2021

New multiarm stars have been synthesized based on polylithium derivatives of high-generation carbosilane dendrimers. In the synthesis of multiarm stars based on the eighth-generation dendrimer, steric hindrances were observed even during the synthesis of a polylithium initiator. Subsequently, this led to chain transfer reactions between growing arms, as well as other side effects. As a result, dense nanogel formations with a higher tendency of ordering than in classical objects of this type were isolated from the reaction mixture. The study of the rheology of multiarm stars based on sixth-generation dendrimers made it possible to determine the activation energies of viscous flow in these objects, which makes it possible to consider them as objects with a macromolecular nature and a reptation flow mechanism.
Substituent Effects on EI-MS Fragmentation Patterns of 5-Allyloxy-1-aryl-tetrazoles and 4-Allyl-1-aryl-tetrazole-5-ones; Correlation with UV-Induced Fragmentation Channels
Authors: Secrieru Alina , Oumeddour Rabah , Cristiano Maria L. S.
Published: May 2021

1,4- and 1,5-disubstituted tetrazoles possess enriched structures and versatile chemistry, representing a challenge for chemists. In the present work, we unravel the fragmentation patterns of a chemically diverse range of 5-allyloxy-1-aryl-tetrazoles and 4-allyl-1-aryl-tetrazolole-5-ones when subjected to electron impact mass spectrometry (EI-MS) and investigate the correlation with the UV-induced fragmentation channels of the matrix-isolated tetrazole derivatives. Our results indicate that the fragmentation pathways of the selected tetrazoles in EI-MS are highly influenced by the electronic effects induced by substitution. Multiple pathways can be envisaged to explain the mechanisms of fragmentation, frequently awarding common final species, namely arylisocyanate, arylazide, arylnitrene, isocyanic acid and hydrogen azide radical cations, as well as allyl/aryl cations. The identified fragments are consistent with those found in previous investigations concerning the photochemical stability of the same class of molecules. This parallelism showcases a similarity in the behaviour of tetrazoles under EI-MS and UV-irradiation in the inert environment of cryogenic matrices of noble gases, providing efficient tools for reactivity predictions, whether for analytical ends or more in-depth studies. Theoretical calculations provide complementary information to articulate predictions of resulting products.
Sustainable Development of Chitosan/Calotropis procera-Based Hydrogels to Stimulate Formation of Granulation Tissue and Angiogenesis in Wound Healing Applications
Authors: Zahid Muhammad , Lodhi Maria , Rehan Zulfiqar Ahmad , Tayyab Hamna , Javed Talha , Shabbir Rubab , Mukhtar Ahmed , EL Sabagh Ayman , Adamski Robert , Sakran Mohamed I. , Siuta Dorota
Published: May 2021

The formation of new scaffolds to enhance healing magnitude is necessarily required in biomedical applications. Granulation tissue formation is a crucial stage of wound healing in which granulation tissue grows on the surface of a wound by the formation of connective tissue and blood vessels. In the present study, porous hydrogels were synthesized using chitosan incorporating latex of the Calotropis procera plant by using a freeze–thaw cycle to stimulate the formation of granulation tissue and angiogenesis in wound healing applications. Structural analysis through Fourier transform infrared (FTIR) spectroscopy confirmed the interaction between chitosan and Calotropis procera. Latex extract containing hydrogel showed slightly higher absorption than the control during water absorption analysis. Thermogravimetric analysis showed high thermal stability of the 60:40 combination of chitosan (CS) and Calotropis procera as compared to all other treatments and controls. A fabricated scaffold application on a chick chorioallantoic membrane (CAM) showed that all hydrogels containing latex extract resulted in a significant formation of blood vessels and regeneration of cells. Overall, the formation of connective tissues and blood capillaries and healing magnitude decreased in ascending order of concentration of extract.
Structural Insights of Three 2,4-Disubstituted Dihydropyrimidine-5-carbonitriles as Potential Dihydrofolate Reductase Inhibitors
Authors: Al-Wahaibi Lamya H. , Shaik Althaf , Elmorsy Mohammed A. , Abdelbaky Mohammed S. M. , Garcia-Granda Santiago , Thamotharan Subbiah , Thiruvenkatam Vijay , El-Emam Ali A.
Published: May 2021

In this report, we describe the structural characterization of three 2,4-disubstituted-dihydropyrimidine-5-carbonitrile derivatives, namely 2-{[(4-nitrophenyl)methyl]sulfanyl}-6-oxo-4-propyl-1,6-dihydropyrimidine-5-carbonitrile 1, 4-(2-methylpropyl)-2-{[(4-nitrophenyl)methyl]sulfanyl}-6-oxo-1,6-dihydropyrimidine-5-carbonitrile 2, and 2-[(2-ethoxyethyl)sulfanyl]-6-oxo-4-phenyl-1,6-dihydropyrimidine-5-carbonitrile monohydrate 3. An X-ray diffraction analysis revealed that these compounds were crystallized in the centrosymmetric space groups and adopt an L-shaped conformation. One of the compounds (3) crystallized with a water molecule. A cyclic motif (R22(8)) mediated by N–H···O hydrogen bond was formed in compounds 1 and 2, whereas the corresponding motif was not favorable, due to the water molecule, in compound 3. The crystal packing of these compounds was analyzed based on energy frameworks performed at the B3LYP/6-31G(d,p) level of theory. Various inter-contacts were characterized using the Hirshfeld surface and its associated 2D-fingerprint plots. Furthermore, a molecular docking simulation was carried out to assess the inhibitory potential of the title compounds against the human dihydrofolate reductase (DHFR) enzyme.
Gibberellin Increases the Bud Yield and Theanine Accumulation in Camellia sinensis (L.) Kuntze
Authors: Li Wei , Xiang Fen , Su Yi , Luo Zhoufei , Luo Weigui , Zhou Lingyun , Liu Hongyan , Xiao Langtao
Published: May 2021

Tea (Camellia sinensis) is one of the most important cash crops in the world. Theanine, as an important amino acid component in tea, is a key quality index for excellent tea quality and high economic value. People increase theanine accumulation in tea mainly through the application of nitrogen fertilizer, shading and pruning. However, these methods are not effective. In this study, we treated tea buds with a 100 μM solution of GA3 containing 1‰ tween-20, investigated the effects of GA3 on theanine accumulation, bud yield, chlorophyll fluorescence parameters and expression level of theanine biosynthesis pathway genes in tea plant by qPCR, LC-MS/MS etc. Results showed that change trends of theanine and GA3 was extremely positively correlated with each other. Exogenous GA3 upregulated the expression level of theanine biosynthesis pathway genes, caused an increase of theanine content (mg·g-1) by 27% in tea leaves compared with Mock, and accelerated the germination of buds and elongation of shoots, which lead to a significant increase of tea yield by 56% (w/w). Moreover, the decrease of chlorophyll contents, photochemical quenching coefficient (qP) and relative electron transport rate (rETR) under GA3 treatment suggested that GA3 reduced photosynthesis in the tender tea leaves, indicating that the decline of carbon assimilation in tea plants was conducive to the nitrogen metabolism, and it was beneficial to the accumulation of theanine. This study provided a new technical and theoretical support for the precise control of tea quality components and phenophase.
Droplet Microfluidic Optimisation Using Micropipette Characterisation of Bio-Instructive Polymeric Surfactants
Authors: Henshaw Charlotte A. , Dundas Adam A. , Cuzzucoli Crucitti Valentina , Alexander Morgan R. , Wildman Ricky , Rose Felicity R. A. J. , Irvine Derek J. , Williams Philip M.
Published: May 2021

Droplet microfluidics can produce highly tailored microparticles whilst retaining monodispersity. However, these systems often require lengthy optimisation, commonly based on a trial-and-error approach, particularly when using bio-instructive, polymeric surfactants. Here, micropipette manipulation methods were used to optimise the concentration of bespoke polymeric surfactants to produce biodegradable (poly(d,l-lactic acid) (PDLLA)) microparticles with unique, bio-instructive surface chemistries. The effect of these three-dimensional surfactants on the interfacial tension of the system was analysed. It was determined that to provide adequate stabilisation, a low level (0.1% (w/v)) of poly(vinyl acetate-co-alcohol) (PVA) was required. Optimisation of the PVA concentration was informed by micropipette manipulation. As a result, successful, monodisperse particles were produced that maintained the desired bio-instructive surface chemistry.
Room Temperature Operation of UV Photocatalytic Functionalized AlGaN/GaN Heterostructure Hydrogen Sensor
Authors: Choi June-Heang , Park Taehyun , Hur Jaehyun , Cha Ho-Young
Published: May 2021

An AlGaN/GaN heterostructure based hydrogen sensor was fabricated using a dual catalyst layer with ZnO-nanoparticles (NPs) atop of Pd catalyst film. The ZnO-NPs were synthesized to have an average diameter of ~10 nm and spin coated on the Pd catalyst layer. Unlike the conventional catalytic reaction, the fabricated sensors exhibited room temperature operation without heating owing to the photocatalytic reaction of the ZnO-NPs with ultraviolet illumination at 280 nm. A sensing response of 25% was achieved for a hydrogen concentration of 4% at room temperature with fast response and recovery times; a response time of 8 s and a recovery time of 11 s.
Facile Fabrication of MnCo2O4/NiO Flower-Like Nanostructure Composites with Improved Energy Storage Capacity for High-Performance Supercapacitors
Authors: Sambasivam Sangaraju , Raghavendra K. V. G. , Yedluri Anil Kumar , Arbi Hammad Mueen , Narayanaswamy Venkatesha , Gopi Chandu V. V. Muralee , Choi Byung-Chun , Kim Hee-Je , Alzahmi Salem , Obaidat Ihab M.
Published: May 2021

Over the past few decades, the application of new novel materials in energy storage system has seen excellent development. We report a novel MnCo2O4/NiO nanostructure prepared by a simplistic chemical bath deposition method and employed it as a binder free electrode in the supercapacitor. The synergistic attraction from a high density of active sites, better transportation of ion diffusion and super-most electrical transportation, which deliver boost electrochemical activities. X-ray diffraction, field-emission scanning electron microscopy, and X-ray photoelectron spectroscopy have been used to investigate the crystallinity, morphology, and elemental composition of the as-synthesized precursors, respectively. Cyclic voltammetry, galvanostatic charge/discharge, and electron impedance spectroscopy have been employed to investigate the electrochemical properties. The unique nanoparticle structures delivered additional well-organized pathways for the swift mobility of electrons and ions. The as-prepared binder-free MnCo2O4/NiO nanocomposite electrode has a high specific capacity of 453.3 C g−1 at 1 Ag−1, and an excellent cycling reliability of 91.89 percent even after 4000 cycles, which are significantly higher than bare MnCo2O4 and NiO electrodes. Finally, these results disclose that the as-fabricated MnCo2O4/NiO electrode could be a favored-like electrode material holds substantial potential and supreme option for efficient supercapacitor and their energy storage-related applications.
Biomass Nanoporous Carbon-Supported Pd Catalysts for Partial Hydrogenation of Biodiesel: Effects of Surface Chemistry on Pd Particle Size and Catalytic Performance
Authors: Udomsap Parncheewa , Meesiri Sirasit , Chollacoop Nuwong , Eiad-Ua Apiluck
Published: May 2021

Two types of cattail flower-derived nanoporous carbon (NPC), i.e., NPC activated with KOH and H3PO4, were produced and characterized using several techniques (e.g., Raman spectroscopy, nitrogen adsorption, and X-ray photoelectron spectroscopy). The influence of the carbon support characteristics on the particle sizes and chemical states of Pd in the synthesized Pd/NPC catalysts, which affect the catalytic activity and product selectivity, was analyzed. The surface chemistry properties of NPC were the main factors influencing the Pd particle size; by contrast, the textural properties did not significantly affect the size of the Pd particles on NPC supports. The use of Pd nanoparticles supported on the rich-functionalized surface carbons obtained by H3PO4 activation led to superior catalytic activity for the polyunsaturated fatty acid methyl ester (poly-FAME) hydrogenation, which could achieve 90% poly-FAME conversion and 84% selectivity towards monounsaturated FAME after a 45-min reaction time. This is due to the small Pd nanoparticle size and the high acidity of the catalysts, which are beneficial for the partial hydrogenation of poly-FAME in biodiesel. Conversely, the Pd nanoparticles supported on the high-surface-area carbon by KOH activation, with large Pd particle size and low acidity, required a longer reaction time to reach similar conversion and product selectivity levels.
Nano-Crystal and Microstructure Formation in Fluoride Photo-Thermo-Refractive Glass Using Chirp-Controlled Ultrafast Laser Bessel Beams
Authors: Zhang Yunjie , Wang Xu , Zhang Guodong , Stoian Razvan , Cheng Guanghua
Published: May 2021

Nano-crystals were formed in the exposed regions of photo-thermo-refractive glass undergoing irradiation with zeroth order chirp-controlled ultrafast laser Bessel beams and subsequent heat treatment. Effects of various writing powers, pulse durations and heat treatment time on the distribution and the size of the nano-crystals were investigated. The results show that nano-crystals’ distribution depended on the laser power density spatial shape, while the size of the nano-crystals is quasi-independent. However, the average diameter of the nano-crystals was affected by the heat treatment time, decreasing from 175 to 105 nm with the time halved. In addition, using crystallographic characterization by X-ray diffraction, the nano-crystal composition in the laser-exposed regions was detected to be sodium fluoride.
Fabrication of Piezoelectric ZnO Nanowires Energy Harvester on Flexible Substrate Coated with Various Seed Layer Structures
Authors: Slimani Tlemcani Taoufik , Justeau Camille , Nadaud Kevin , Alquier Daniel , Poulin-Vittrant Guylaine
Published: May 2021

Flexible piezoelectric nanogenerators (PENGs) are very attractive for mechanical energy harvesting due to their high potential for realizing self-powered sensors and low-power electronics. In this paper, a PENG that is based on zinc oxide (ZnO) nanowires (NWs) is fabricated on flexible and transparent Polydimethylsiloxane (PDMS) substrate. The ZnO NWs were deposited on two different seed layer structures, i.e., gold (Au)/ZnO and tin-doped indium-oxide (ITO)/ZnO, using hydrothermal synthesis. Along with the structural and morphological analyses of ZnO NWs, the electrical characterization was also investigated for ZnO NWs-based flexible PENGs. In order to evaluate the suitability of the PENG device structure, the electrical output performance was studied. By applying a periodic mechanical force of 3 N, the ZnO NWs-based flexible PENG generated a maximum root mean square (RMS) voltage and average power of 2.7 V and 64 nW, respectively. Moreover, the comparison between the fabricated device performances shows that a higher electrical output can be obtained when ITO/ZnO seed layer structure is adopted. The proposed ZnO NWs-based PENG structure can provide a flexible and cost-effective device for supplying portable electronics.
PVDF HFP_RuO2 Nanocomposite Aerogels Produced by Supercritical Drying for Electrochemical Oxidation of Model Tannery Wastewaters
Authors: Sarno Maria , Scudieri Carmela , Ponticorvo Eleonora , Baldino Lucia , Cardea Stefano , Reverchon Ernesto
Published: May 2021

A supercritical CO2 drying process was used to prepare an innovative nanocomposite, formed by a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF HFP) aerogel loaded with RuO2 nanoparticles. The produced nanocomposites, at 10% and 60% w/w of RuO2, were tested for the electrochemical oxidation of model tannery wastewaters. The effect of the electrochemical oxidation parameters, like pH, temperature, and current density, on tannic acid, intermediates, and chemical oxygen demand (COD) removal, was investigated. In particular, the electrolysis of a simulated real tannery wastewater, using PVDF HFP_RuO2 60, was optimized working at pH 10, 40 °C, and setting the current density at 600 A/m2. Operating in this way, surfactants, sulfides, and tannins oxidation was achieved in about 2.5 h, ammonium nitrogen oxidation in 3 h, and COD removal in 5 h. When chloride-containing solutions were tested, the purification was due to indirect electrolysis, related to surface redox reactions generating active chlorine. Moreover, sulfide ions were converted into sulfates and ammonium nitrogen in gaseous N2.
Nanodiamond Particles as Secondary Additive for Polyalphaolefin Oil Lubrication of Steel–Aluminium Contact
Authors: Raina Ankush , Irfan Ul Haq Mir , Anand Ankush , Mohan Sanjay , Kumar Rajiv , Jayalakshmi Subramanian , Arvind Singh Ramachandra
Published: May 2021

Nanodiamond (ND) particles are effective lubricant additives. Attention of research has shifted towards investigating the particles as secondary additives. ND particles provide more benefits as secondary additives than as the sole lubricant additive for steel–steel contacts. In this work, the influence of ND particles as secondary additives on oil lubrication of steel–aluminium tribopair (hard–soft contact) was examined. AISI 52100 steel balls were slid against AA2024 aluminium alloy discs, in the presence of polyalphaolefin (PAO) base oil, in boundary lubrication regime (applied normal load: 10 N to 50 N). Primary additives were copper oxide (CuO) and hexagonal boron nitride (h-BN) nanoparticles. The addition of ND particles to PAO, with CuO and h-BN as primary additives, at the lowest applied normal load of 10 N: (i) decreased the volumetric wear of the aluminium discs by 28% and 63%, respectively, and (ii) decreased the coefficient of friction by 15% and 33%, respectively. At the highest applied normal load of 50 N, it: (i) decreased the volumetric wear of the aluminium discs by 20% and 38%, respectively, and (ii) decreased the coefficient of friction by 5.4% and 8%, respectively. ND particles as secondary additives significantly reduce energy loss and power loss as a consequence of an effective reduction in friction during sliding. Unique characteristics of ND particles—such as their (a) physicochemical and thermal properties, (b) ball bearing and polishing effects and (c) synergistic interaction with primary additives to form stable tribofilms—enhance the lubrication performance of steel–aluminium contact. ND particles in combination with h-BN nanoparticles showed the best performance, due to better synergy between the primary additive and the secondary additive. Results from the investigation indicate that ND particles taken as secondary additives in small amount (0.2 wt%) can improve oil lubrication performance of hard–soft contacts in engineering systems.
Chitosan Nanoparticles as a Promising Nanomaterial for Encapsulation of Pomegranate (Punica granatum L.) Peel Extract as a Natural Source of Antioxidants
Authors: Soltanzadeh Maral , Peighambardoust Seyed Hadi , Ghanbarzadeh Babak , Mohammadi Maryam , Lorenzo José M.
Published: May 2021

The encapsulation of pomegranate peel extract (PPE) in chitosan nanoparticles (CSNPs) is an advantageous strategy to protect sensitive constituents of the extract. This study was aimed to develop PPE-loaded CSNPs and characterize their physical, structural morphology, antioxidant and antimicrobial properties. Spherical NPs were successfully synthesized with a mean diameter of 174–898 nm, a zeta potential (ZP) of +3 – +36 mV, an encapsulation efficiency (EE) of 26–70%, and a loading capacity (LC) of 14–21% depending on their loaded extract concentrations. Based on these results, CSNPs with chitosan:PPE ratio of 1:0.50 (w/w) exhibited good physical stability (ZP = 27 mV), the highest loading (LC = 20%) and desirable encapsulation efficiency (EE = 51%), and thus, selected as optimally loaded NPs. The FTIR analysis of PPE-CSNPs demonstrated no spectral changes indicating no possible chemical interaction between the PPE and CSNPs, which confirms that the PPE was physically entrapped within NPs. Moreover, FTIR spectra of pure PPE showed specific absorption bands (at 3293–3450 cm−1) attributed to the incidence of phenolic compounds, such as tannic acid, ellagic acid and gallic acid. Total phenolic content (TPC) and antioxidant analysis of selected CSNPs revealed that the encapsulated NPs had significantly lower TPC and antioxidant activity than those of pure PPE, indicating that CSNPs successfully preserved PPE from rapid release during the measurements. Antibacterial tests indicated that pure PPE and PPE-loaded CSNPs effectively retarded the growth of Gram-positive S. aureus with a minimum inhibitory concentration (MIC) of 0.27 and 1.1 mg/mL, respectively. Whereas Gram-negative E. coli, due to its protective cell membrane, was not retarded by pure PPE and PPE-CSNPs at the MIC values tested in this study. Gas chromatography-mass spectroscopy analysis confirmed the incidence of various phytochemicals, including phenolic compounds, fatty acids, and furfurals, with possible antioxidant or antimicrobial properties. Overall, CSNPs can be regarded as suitable nanomaterials for the protection and controlled delivery of natural antioxidants/antimicrobials, such as PPE in food packaging applications.
Carbon-Supported Trimetallic Catalysts (PdAuNi/C) for Borohydride Oxidation Reaction
Authors: ElSheikh Ahmed , Backović Gordana , Oliveira Raisa , Sequeira César , McGregor James , Šljukić Biljana , Santos Diogo
Published: May 2021

The synthesis of palladium-based trimetallic catalysts via a facile and scalable synthesis procedure was shown to yield highly promising materials for borohydride-based fuel cells, which are attractive for use in compact environments. This, thereby, provides a route to more environmentally friendly energy storage and generation systems. Carbon-supported trimetallic catalysts were herein prepared by three different routes: using a NaBH4-ethylene glycol complex (PdAuNi/CSBEG), a NaBH4-2-propanol complex (PdAuNi/CSBIPA), and a three-step route (PdAuNi/C3-step). Notably, PdAuNi/CSBIPA yielded highly dispersed trimetallic alloy particles, as determined by XRD, EDX, ICP-OES, XPS, and TEM. The activity of the catalysts for borohydride oxidation reaction was assessed by cyclic voltammetry and RDE-based procedures, with results referenced to a Pd/C catalyst. A number of exchanged electrons close to eight was obtained for PdAuNi/C3-step and PdAuNi/CSBIPA (7.4 and 7.1, respectively), while the others, PdAuNi/CSBEG and Pd/CSBIPA, presented lower values, 2.8 and 1.2, respectively. A direct borohydride-peroxide fuel cell employing PdAuNi/CSBIPA catalyst in the anode attained a power density of 47.5 mW cm−2 at room temperature, while the elevation of temperature to 75 °C led to an approximately four-fold increase in power density to 175 mW cm−2. Trimetallic catalysts prepared via this synthesis route have significant potential for future development.
Novel Three-Dimensional Graphene-Like Networks Loaded with Fe3O4 Nanoparticles for Efficient Microwave Absorption
Authors: Shang Tao , Lu Qingshan , Zhao Jianjun , Chao Luomeng , Qin Yanli , Ren Ningyu , Yun Yuehou , Yun Guohong
Published: May 2021

A novel three-dimensional graphene-like networks material (3D-GLN) exhibiting the hierarchical porous structure was fabricated with a large-scale preparation method by employing an ion exchange resin as a carbon precursor. 3D-GLN was first studied as the effective microwave absorbing material. As indicated from the results of the electromagnetic parameter tests, and the minimum reflection loss (RL) of the 3D-GLN reached −34.75 dB at the frequency of 11.7 GHz. To enhance the absorption performance of the nonmagnetic 3D-GLN, the magnetic Fe3O4 nanoparticles were loaded on the surface of the 3D-GLN by using the hydrothermal method to develop the 3D-GLN/Fe3O4 hybrid. The hybrid exhibited the prominent absorbing properties. Under the matching thickness of 3.0 mm, the minimum RL value of hybrid reached −46.8 dB at 11.8 GHz. In addition, under the thickness range of 2.0–5.5 mm, the effective absorption bandwidth (RL < 10 dB) was 13.0 GHz, which covered part of the C-band and the entire X-band, as well as the entire Ku-band. The significant microwave absorption could be attributed to the special 3D network structure exhibited by the hybrid and the synergistic effect exerted by the graphene and the Fe3O4 nanoparticles. As revealed from the results, the 3D-GLN/Fe3O4 hybrid could be a novel microwave absorber with promising applications.
Synthesis of Fe1-xS Nanoparticles with Various Superstructures by a Simple Thermal Decomposition Route and Their Magnetic Properties
Authors: Spivakov Aleksandr A. , Lin Chun-Rong , Chang Yu-Chuan , Chen Ying-Zhen
Published: May 2021

Pyrrhotite nanoparticles with 5C and 3C superstructures were synthesized via a simple one-step thermal decomposition method in which hexadecylamine was used as a solvent at various reaction temperatures (TR). Structural analysis showed that at TR = 360 °C, almost uniform in size and shape Fe7S8 nanoparticles with 3C superstructure are formed, and an increase in the reaction temperature leads to the formation of Fe9S10 nanoparticles (5C superstructure), herewith a significant increase in the size of nanoparticles is observed. High-temperature magnetic measurements in 5 repeated heating-cooling cycles revealed that after the first heating branch in the Fe9S10 samples, the λ—Peak transition disappears, and the magnetization has a Weiss-type behavior characteristic of the Fe7S8 sample. The change in the behavior of magnetization can be explained by the redistribution of iron vacancies, which changes the initial phase composition of nanoparticles.
A Review of Fluorescent Carbon Dots, Their Synthesis, Physical and Chemical Characteristics, and Applications
Authors: Jorns Mychele , Pappas Dimitri
Published: May 2021

Carbon dots (CDs) are a particularly useful type of fluorescent nanoparticle that demonstrate biocompatibility, resistance to photobleaching, as well as diversity in composition and characteristics amongst the different types available. There are two main morphologies of CDs: Disk-shaped with 1–3 stacked sheets of aromatic carbon rings and quasi-spherical with a core-shell arrangement having crystalline and amorphous properties. They can be synthesized from various potentially environmentally friendly methods including hydrothermal carbonization, microwaving, pyrolysis or combustion, and are then purified via one or more methods. CDs can have either excitation wavelength-dependent or -independent emission with each having their own benefits in microscopic fluorescent imaging. Some CDs have an affinity for a particular cell type, organelle or chemical. This property allows the CDs to be used as sensors in a biological environment and can even provide quantitative information if the quenching or intensity of their fluorescence is dependent on the concentration of the analyte. In addition to fluorescent imaging, CDs can also be used for other applications including drug delivery, quality control, photodynamic therapy, and photocatalysis.
Hollow CoP/FeP4 Heterostructural Nanorods Interwoven by CNT as a Highly Efficient Electrocatalyst for Oxygen Evolution Reactions
Authors: Liu Yanfang , Li Yong , Wu Qi , Su Zhe , Wang Bin , Chen Yuanfu , Wang Shifeng
Published: May 2021

Electrolysis of water to produce hydrogen is crucial for developing sustainable clean energy and protecting the environment. However, because of the multi-electron transfer in the oxygen evolution reaction (OER) process, the kinetics of the reaction is seriously hindered. To address this issue, we designed and synthesized hollow CoP/FeP4 heterostructural nanorods interwoven by carbon nanotubes (CoP/FeP4@CNT) via a hydrothermal reaction and a phosphorization process. The CoP/FeP4@CNT hybrid catalyst delivers prominent OER electrochemical performances: it displays a substantially smaller Tafel slope of 48.0 mV dec−1 and a lower overpotential of 301 mV at 10 mA cm−2, compared with an RuO2 commercial catalyst; it also shows good stability over 20 h. The outstanding OER property is mainly attributed to the synergistic coupling between its unique CNT-interwoven hollow nanorod structure and the CoP/FeP4 heterojunction, which can not only guarantee high conductivity and rich active sites, but also greatly facilitate the electron transfer, ion diffusion, and O2 gas release and significantly enhance its electrocatalytic activity. This work offers a facile method to develop transition metal-based phosphide heterostructure electrocatalysts with a unique hierarchical nanostructure for high performance water oxidation.
Beyond Nutrient Deficiency—Opportunities to Improve Nutritional Status and Promote Health Modernizing DRIs and Supplementation Recommendations
Authors: McBurney Michael I. , Blumberg Jeffrey B. , Costello Rebecca B. , Eggersdorfer Manfred , Erdman John W. , Harris William S. , Johnson Elizabeth J. , Hazels Mitmesser Susan , Post Robert C. , Rai Deshanie , Schurgers Leon J.
Published: May 2021

The US Dietary Guidelines for Americans (DGA) provide dietary recommendations to meet nutrient needs, promote health, and prevent disease. Despite 40 years of DGA, the prevalence of under-consumed nutrients continues in the US and globally, although dietary supplement use can help to fill shortfalls. Nutrient recommendations are based on Dietary Reference Intakes (DRIs) to meet the nutrient requirements for nearly all (97 to 98 percent) healthy individuals in a particular life stage and gender group and many need to be updated using current evidence. There is an opportunity to modernize vitamin and mineral intake recommendations based on biomarker or surrogate endpoint levels needed to ‘prevent deficiency’ with DRIs based on ranges of biomarker or surrogate endpoints levels that support normal cell/organ/tissue function in healthy individuals, and to establish DRIs for bioactive compounds. We recommend vitamin K and Mg DRIs be updated and DRIs be established for lutein and eicosapentaenoic and docosahexaenoic acid (EPA + DHA). With increasing interest in personalized (or precision) nutrition, we propose greater research investment in validating biomarkers and metabolic health measures and the development and use of inexpensive diagnostic devices. Data generated from such approaches will help elucidate optimal nutrient status, provide objective evaluations of an individual’s nutritional status, and serve to provide personalized nutrition guidance.