bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural and Optical Characterization of ZnS Ultrathin Films Prepared by Low-Temperature ALD from Diethylzinc and 1.5-Pentanedithiol after Various Annealing Treatments
Authors: Włodarski Maksymilian , Chodorow Urszula , Jóźwiak Stanisław , Putkonen Matti , Durejko Tomasz , Sajavaara Timo , Norek Małgorzata
Published: September 2019

The structural and optical evolution of the ZnS thin films prepared by atomic layer deposition (ALD) from the diethylzinc (DEZ) and 1,5-pentanedithiol (PDT) as zinc and sulfur precursors was studied. A deposited ZnS layer (of about 60 nm) is amorphous, with a significant S excess. After annealing, the stoichiometry improved for annealing temperatures ≥400 °C and annealing time ≥2 h, and 1:1 stoichiometry was obtained when annealed at 500 °C for 4 h. ZnS crystallized into small crystallites (1–7 nm) with cubic sphalerite structure, which remained stable under the applied annealing conditions. The size of the crystallites (D) tended to decrease with annealing temperature, in agreement with the EDS data (decreased content of both S and Zn with annealing temperature); the D for samples annealed at 600 °C (for the time ≤2 h) was always the smallest. Both reflectivity and ellipsometric spectra showed characteristics typical for quantum confinement (distinct dips/peaks in UV spectral region). It can thus be concluded that the amorphous ZnS layer obtained at a relatively low temperature (150 °C) from organic S precursor transformed into the layers built of small ZnS nanocrystals of cubic structure after annealing at a temperature range of 300–600 °C under Ar atmosphere.
Environmental-Friendly Modifications of Zeolite to Increase Its Sorption and Anion Exchange Properties, Physicochemical Studies of the Modified Materials
Authors: Cieśla Jolanta , Franus Wojciech , Franus Małgorzata , Kedziora Karolina , Gluszczyk Justyna , Szerement Justyna , Jozefaciuk Grzegorz
Published: September 2019

Zeolites, naturally possessing a high negative surface charge and large specific surface, are used in agriculture as cationic fertilizers, water holders, heavy metals, and organic pollutants sorbents. Since some nutrients occur in anionic forms, there is a need to modify the zeolite surface to hold anions. In this study, hydrogen (hydrochloric acid), iron (Fe2+ and Fe3+), and aluminum cations as well as the influence of sodium hydroxide modifiers on the specific surface area, water vapor, adsorption energy, fractal dimension, mesopore volumes and radii, electrokinetic (zeta) potential, and isoelectric point were investigated. The use of alkali solution did not affect the zeolite properties significantly, whereas hydrogen, iron, and treatments with aluminum cations resulted in an increase in the specific surface area, mesopore volumes, and radii, and a decrease in the water-binding forces. Aluminum cations were the most effective in recharging the zeolite surface from negative to positive, shifting the isoelectric point toward the highest values. Calcination enlarged the negative surface charge and mesopore radius, and diminished the surface area and mesopore volume. The modified zeolites are promising carriers of anionic nutrients, large surface area sorbents, and suppliers of water for plant roots in soil.
Effects of T5 Treatment on Microstructure and Mechanical Properties at Elevated Temperature of AZ80-Ag Alloy
Authors: Zeng Gang , Liu Chuming , Gao Yonghao , Jiang Shunong , Yu Shilun , Chen Zhiyong
Published: September 2019

Effects of T5 treatment on microstructure and mechanical properties at elevated temperature of hot-ring-rolled (HRRed) AZ80-Ag magnesium alloy were systematically investigated. Results show that, after aging at 175 °C for 36 h, discontinuous and continuous precipitates form inside grains, with the former one taking up a volume fraction of ~64.9%. T5 treatment improves the tensile strength at ambient temperature of the alloy but weakens its tensile strength and creep resistance at elevated temperatures (120–175 °C), indicating opposite effects of T5 on mechanical properties at ambient and elevated temperatures. During creep at 120–175 °C and under 70–90 MPa, the dynamic precipitation process in HRRed specimen is accelerated with increasing temperature. At 150–175 °C massive nucleation and growth of dynamic discontinuous precipitates could result in an atypical primary creep stage, consisting of deceleration and acceleration creep stages, which is reported in wrought Mg-Al-based alloy for the first time. Such primary creep stage can be eliminated by T5 treatment. Besides, diffusion-controlled dislocation creep is the dominant creep mechanism for both HRRed and T5 specimens.
Exact Solutions for a Modified Schrödinger Equation
Authors: Benia Yassine , Ruggieri Marianna , Scapellato Andrea
Published: September 2019

The aim of this paper was to propose a systematic study of a ( 1 + 1 ) -dimensional higher order nonlinear Schrödinger equation, arising in two different contexts regarding the biological science and the nonlinear optics. We performed a Lie symmetry analysis and here present exact solutions of the equation.
Dual Crosslinked Methacrylated Alginate Hydrogel Micron Fibers and Tissue Constructs for Cell Biology
Authors: Gao Yingjun , Jin Xiangyu
Published: September 2019

As an important natural polysaccharide biomaterial from marine organisms, alginate and its derivatives have shown great potential in the fabrication of biomedical materials such as tissue engineering, cell biology, drug delivery, and pharmaceuticals due to their excellent biological activity and controllable physicochemical properties. Ionic crosslinking is the most common method used in the preparation of alginate-based biomaterials, but ionic crosslinked alginate hydrogels are prone to decompose in physiological solution, which hinders their applications in biomedical fields. In this study, dual crosslinked alginate hydrogel microfibers were prepared for the first time. The ionic crosslinked methacrylated alginate (Alg-MA) hydrogel microfibers fabricated by Microfluidic Fabrication (MFF) system were exposed to ultraviolet (UV) light and covalent crosslink between methacrylate groups avoided the fracture of dual crosslinked macromolecular chains in organizational environment. The chemical structures, swelling ratio, mechanical performance, and stability were investigated. Cell-encapsulated dual crosslinked Alg-MA hydrogel microfibers were fabricated to explore the application in tissue engineering for the first time. The hydrogel microfibers provided an excellent 3D distribution and growth conditions for cells. Cell-encapsulated Alg-MA microfibers scaffolds with functional 3D tissue structures were developed which possessed great potential in the production of next-generation scaffolds for tissue engineering and regenerative medicine.
Physicochemical and Functional Properties of Type I Collagens in Red Stingray (Dasyatis akajei) Skin
Authors: Chen Junde , Li Jianying , Li Zhongbao , Yi Ruizao , Shi Shenjia , Wu Kunyuan , Li Yushuang , Wu Sijia
Published: September 2019

Collagen is widely used in the pharmaceutical, tissue engineering, nutraceutical, and cosmetic industries. In this study, acid-soluble collagen (ASC) and pepsin-soluble collagen (PSC) were extracted from the skin of red stingray, and its physicochemical and functional properties were investigated. The yields of ASC and PSC were 33.95 ± 0.7% and 37.18 ± 0.71% (on a dry weight basis), respectively. ASC and PSC were identified as type I collagen by Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE) analysis, possessing a complete triple helix structure as determined by UV absorption, Fourier transform infrared, circular dichroism, and X-ray diffraction spectroscopy. Contact angle experiments indicated that PSC was more hydrophobic than ASC. Thermal stability tests revealed that the melting temperature of PSC from red stingray skin was higher than that of PSC from duck skin, and the difference in the melting temperature between these two PSCs was 9.24 °C. Additionally, both ASC and PSC were functionally superior to some other proteins from terrestrial sources, such as scallop gonad protein, whey protein, and goose liver protein. These results suggest that PSC from red stingray skin could be used instead of terrestrial animal collagen in drugs, foods, cosmetics, and biological functional materials, and as scaffolds for bone regeneration.
A Comprehensive Review of Bioactive Peptides from Marine Fungi and Their Biological Significance
Authors: Youssef Fadia S. , Ashour Mohamed L. , Singab Abdel Nasser B. , Wink Michael
Published: September 2019

Fungal marine microorganisms are a valuable source of bioactive natural products. Fungal secondary metabolites mainly comprise alkaloids, terpenoids, peptides, polyketides, steroids, and lactones. Proteins and peptides from marine fungi show minimal human toxicity and less adverse effects comparable to synthetic drugs. This review summarizes the chemistry and the biological activities of peptides that were isolated and structurally elucidated from marine fungi. Relevant fungal genera including Acremonium, Ascotricha, Aspergillus, Asteromyces, Ceratodictyon, Clonostachys, Emericella, Exserohilum, Microsporum, Metarrhizium, Penicillium, Scytalidium, Simplicillium, Stachylidium, Talaromyces, Trichoderma, as well as Zygosporium were extensively reviewed. About 131 peptides were reported from these 17 genera and their structures were unambiguously determined using 1D and 2D NMR (one and two dimensional nuclear magnetic resonance) techniques in addition to HRMS (high resolution mass spectrometry). Marfey and Mosher reactions were used to confirm the identity of these compounds. About 53% of the isolated peptides exhibited cytotoxic, antimicrobial, and antiviral activity, meanwhile, few of them showed antidiabetic, lipid lowering, and anti-inflammatory activity. However 47% of the isolated peptides showed no activity with respect to the examined biological activity and thus required further in depth biological assessment. In conclusion, when searching for bioactive natural products, it is worth exploring more peptides of fungal origin and assessing their biological activities.
Antimicrobial Sesquiterpenoid Derivatives and Monoterpenoids from the Deep-Sea Sediment-Derived Fungus Aspergillus versicolor SD-330
Authors: Li Xiao-Dong , Li Xiao-Ming , Yin Xiu-Li , Li Xin , Wang Bin-Gui
Published: September 2019

Two new antimicrobial bisabolane-type sesquiterpenoid derivatives, ent-aspergoterpenin C (compound 1) and 7-O-methylhydroxysydonic acid (2), and two new butyrolactone-type monoterpenoids, pestalotiolactones C (3) and D (4), along with a known monoterpenoid pestalotiolactone A (5) and four known bisabolane sesquiterpenoids (6−9), were isolated and identified from the deep-sea sediment-derived fungus Aspergillus versicolor SD-330. The structures of these compounds were elucidated on the basis of spectroscopic analysis, and the absolute configurations of the new compounds 1−4 were determined by the combination of NOESY and TDDFT-ECD calculations and X-ray crystallographic analysis. Additionally, we first determined and reported the absolute configuration of the known monoterpenoid pestalotiolactone A (5) through the X-ray crystallographic experiment. All of these isolated compounds were evaluated for antimicrobial activities against human and aquatic pathogenic bacteria. Compounds 1, 2, 6 and 9 exhibited selective inhibitory activities against zoonotic pathogenic bacteria such as Escherichia coli, Edwardsiella tarda, Vibrio anguillarum and V. harveyi, with MIC values ranging from 1.0 to 8.0 μg/mL.
Unraveling the Detoxification Mechanism of 2,4-Dichlorophenol by Marine-Derived Mesophotic Symbiotic Fungi Isolated from Marine Invertebrates
Authors: Nikolaivits Efstratios , Agrafiotis Andreas , Termentzi Aikaterini , Machera Kyriaki , Le Goff Géraldine , Álvarez Pedro , Chavanich Suchana , Benayahu Yehuda , Ouazzani Jamal , Fokialakis Nikolas , Topakas Evangelos
Published: September 2019

Chlorophenols (CPs) are environmental pollutants that are produced through various anthropogenic activities and introduced in the environment. Living organisms, including humans, are exposed to these toxic xenobiotics and suffer from adverse health effects. More specifically, 2,4-dichlorophenol (2,4-DCP) is released in high amounts in the environment and has been listed as a priority pollutant by the US Environmental Protection Agency. Bioremediation has been proposed as a sustainable alternative to conventional remediation methods for the detoxification of phenolic compounds. In this work, we studied the potential of fungal strains isolated as symbionts of marine invertebrates from the underexplored mesophotic coral ecosystems. Hence, the unspecific metabolic pathways of these fungal strains are being explored in the present study, using the powerful analytical capabilities of a UHPLC-HRMS/MS. The newly identified 2,4-DCP metabolites add significantly to the knowledge of the transformation of such pollutants by fungi, since such reports are scarce.
A Shared-Electrode and Nested-Tube Structure Triboelectric Nanogenerator for Motion Energy Harvesting
Authors: Tian Zhumei , Shao Guicheng , Zhang Qiong , Geng Yanan , Chen Xi
Published: September 2019

Triboelectric nanogenerators with the function of harvesting human motion energy have attracted wide attention. Here, we demonstrate a shared-electrode and nested-tube structure triboelectric nanogenerator (SNTN) for harvesting human motion energy. The design of the SNTN employs flexible silicone rubber as the negative friction material and Ni-coated polyester conductive textile as the positive friction material and the electrode material. The entire structure consists of an inner triboelectric unit and an outer triboelectric unit. The inner triboelectric unit is formed by a hollow inner tube and a hollow middle tube, while the hollow middle tube and a hollow outer tube constitute the outer triboelectric unit. The hollow middle tube is used as the shared tube, and the electrode in the middle tube is used as the shared electrode of the two triboelectric units. Our research demonstrates that the output performance of the SNTN was improved significantly compared with a single triboelectric unit due to the cooperation of the two triboelectric units. When the SNTN is pressed by 300 N external force, output open-circuit voltage of 180 V and output short-circuit current of 8.5 μA can be obtained. The output electrical energy can light up 31 light-emitting diodes (LEDs) connected serially (displaying “XZTC”) and can drive a digital clock after rectifying storage, which shows application prospects in the field of illuminating devices and portable electronics.
Isolation, Identification, and Characterization of Pectinolytic Yeasts for Starter Culture in Coffee Fermentation
Authors: Haile Mesfin , Kang Won Hee
Published: September 2019

This experiment was carried out to identify and select pectinolytic yeasts that have potential use as a starter culture for coffee fermentation during wet processing. The coffee fruit was fermented for 48 h at 28 °C and a sample was taken from the fermented solution and spread onto yeast extract-peptone-dextrose agar (YPDA) media and incubated at 28 °C. A total of 28 yeasts were isolated, eight of which had the ability to produce pectinase enzymes. The species of those eight yeasts were molecularly identified and confirmed. These yeasts are Wickerhamomyces anomalus (strain KNU18Y3), Saccharomycopsis fibuligera (strain KNU18Y4), Papiliotrema flavescens (strain KNU18Y5 and KNU18Y6), Pichia kudriavzevii (strain KNU18Y7 and KNU18Y8), and Saccharomyces cerevisiae (strain KNU18Y12 and KNU18Y13). The pectin degradation index of S. fibuligera (strain KNU18Y4), W. anomalus (strain KNU18Y3), and P. flavescens (strain KNU18Y6) were higher compared to the others, at 178%, 160%, and 152%, respectively. The pectinase enzyme assays were made on two growth media: coffee pulp media (CPM) and synthetic pectin media (SPM). S. fibuligera (strain KNU18Y4) and W. anomalus (strain KNU18Y3) had great potential in producing polygalacturonase (PG) and pectin lyase (PL) compared to others in both media. However, S. cerevisiae strains (KNU18Y12 and KNU18Y13) produced higher pectin methylesterase (PME). Using MEGA 6 software, the phylogenetic trees were constructed to determine the evolutionary relationship of newly identified yeasts from our experiment and previously published yeast species. The sequences of the yeasts were deposited in the National Center for Biotechnology Information (NCBI) database.
Probiotic Bifunctionality of Bacillus subtilis—Rescuing Lactic Acid Bacteria from Desiccation and Antagonizing Pathogenic Staphylococcus aureus
Authors: Kimelman Hadar , Shemesh Moshe
Published: September 2019

Live probiotic bacteria obtained with food are thought to have beneficial effects on a mammalian host, including their ability to reduce intestinal colonization by pathogens. To ensure the beneficial effects, the probiotic cells must survive processing and storage of food, its passage through the upper gastrointestinal tract (GIT), and subsequent chemical ingestion processes until they reach their target organ. However, there is considerable loss of viability of the probiotic bacteria during the drying process, in the acidic conditions of the stomach, and in the high bile concentration in the small intestine. Bacillus subtilis, a spore-forming probiotic bacterium, can effectively maintain a favorable balance of microflora in the GIT. B. subtilis produces a protective extracellular matrix (ECM), which is shared with other probiotic bacteria; thus, it was suggested that this ECM could potentially protect an entire community of probiotic cells against unfavorable environmental conditions. Consequently, a biofilm-based bio-coating system was developed that would enable a mutual growth of B. subtilis with different lactic acid bacteria (LAB) through increasing the ECM production. Results of the study demonstrate a significant increase in the survivability of the bio-coated LAB cells during the desiccation process and passage through the acidic environment. Thus, it provides evidence about the ability of B. subtilis in rescuing the desiccation-sensitive LAB, for instance, Lactobacillus rhamnosus, from complete eradication. Furthermore, this study demonstrates the antagonistic potential of the mutual probiotic system against pathogenic bacteria such as Staphylococcus aureus. The data show that the cells of B. subtilis possess robust anti-biofilm activity against S. aureus through activating the antimicrobial lipopeptide production pathway.
Synthesis and Biological Evaluation of New Glycoconjugated LDH Inhibitors as Anticancer Agents
Authors: D’Andrea Felicia , Vagelli Giulia , Granchi Carlotta , Guazzelli Lorenzo , Tuccinardi Tiziano , Poli Giulio , Iacopini Dalila , Minutolo Filippo , Di Bussolo Valeria
Published: September 2019

Conjugation of known biologically active molecules to carbohydrate frameworks represents a valuable option for the preparation of hybrid, structurally-related families of compounds with the aim of modulating their biological response. Therefore, we present here a study on the preparation of d-galacto, d-manno, d-gluco, and d-lactose glycoconjugates of an established N-hydroxyindole-based (NHI) inhibitor of lactated dehydrogenase (LDH). Structural variations involved the sugar stereochemistry and size as well as the anchoring point of the NHI on the carbohydrate frame (either C-1 or C-6). In the case of the galactose anomeric glycoconjugate (C-1), intriguing solvent-dependent effects were observed in the glycosylation stereochemical outcome. The biological activity of the deprotected glycoconjugates in contrasting lactate formation and cancer cell proliferation are described.
Chemically Responsive Hydrogel Deformation Mechanics: A Review
Authors: Fennell Eanna , Huyghe Jacques M.
Published: September 2019

A hydrogel is a polymeric three-dimensional network structure. The applications of this material type are diversified over a broad range of fields. Their soft nature and similarity to natural tissue allows for their use in tissue engineering, medical devices, agriculture, and industrial health products. However, as the demand for such materials increases, the need to understand the material mechanics is paramount across all fields. As a result, many attempts to numerically model the swelling and drying of chemically responsive hydrogels have been published. Material characterization of the mechanical properties of a gel bead under osmotic loading is difficult. As a result, much of the literature has implemented variants of swelling theories. Therefore, this article focuses on reviewing the current literature and outlining the numerical models of swelling hydrogels as a result of exposure to chemical stimuli. Furthermore, the experimental techniques attempting to quantify bulk gel mechanics are summarized. Finally, an overview on the mechanisms governing the formation of geometric surface instabilities during transient swelling of soft materials is provided.
Indolylboronic Acids: Preparation and Applications
Authors: Čubiňák Marek , Edlová Tereza , Polák Peter , Tobrman Tomáš
Published: September 2019

Indole derivatives are associated with a variety of both biological activities and applications in the field of material chemistry. A number of different strategies for synthesizing substituted indoles by means of the reactions of indolylboronic acids with electrophilic compounds are considered the methods of choice for modifying indoles because indolylboronic acids are easily available, stable, non-toxic and new reactions using indolylboronic acids have been described in the literature. Thus, the aim of this review is to summarize the methods available for the preparation of indolylboronic acids as well as their chemical transformations. The review covers the period 2010–2019.
Design, Synthesis and Biological Evaluation of Pentacyclic Triterpene Derivatives: Optimization of Anti-ABL Kinase Activity
Authors: I. Ciftci Halil , O. Radwan Mohamed , E. Ozturk Safiye , Ulusoy N. Gokce , Sozer Ece , E. Ellakwa Doha , Ocak Zeynep , Can Mustafa , F.S. Ali Taha , I. Abd-Alla Howaida , Yayli Nurettin , Tateishi Hiroshi , Otsuka Masami , Fujita Mikako
Published: September 2019

Imatinib, an Abelson (ABL) tyrosine kinase inhibitor, is a lead molecular-targeted drug against chronic myelogenous leukemia (CML). To overcome its resistance and adverse effects, new inhibitors of ABL kinase are needed. Our previous study showed that the benzyl ester of gypsogenin (1c), a pentacyclic triterpene, has anti-ABL kinase and a subsequent anti-CML activity. To optimize its activities, benzyl esters of carefully selected triterpenes (PT1–PT6), from different classes comprising oleanane, ursane and lupane, and new substituted benzyl esters of gypsogenin (GP1–GP5) were synthesized. All of the synthesized compounds were purified and charachterized by different spectroscopic methods. Cytotoxicity of the parent triterpenes and the synthesized compounds against CML cell line K562 was examined; revealing three promising compounds PT5, GP2 and GP5 (IC50 5.46, 4.78 and 3.19 μM, respectively). These compounds were shown to inhibit extracellular signal-regulated kinase (ERK) downstream signaling, and induce apoptosis in K562 cells. Among them, PT5 was identified to have in vitro activity (IC50 = 1.44 μM) against ABL1 kinase, about sixfold of 1c, which was justified by molecular docking. The in vitro activities of GP2 and GP5 are less than PT5, hence they were supposed to possess other more mechanisms of cytotoxicity. In general, our design and derivatizations resulted in enhancing the activity against ABL1 kinase and CML cells.
Cell-Penetrating Peptide and Transferrin Co-Modified Liposomes for Targeted Therapy of Glioma
Authors: Wang Xi , Zhao Yarong , Dong Shiyan , Lee Robert J. , Yang Dongsheng , Zhang Huan , Teng Lesheng
Published: September 2019

Glioma is one of the most aggressive and common malignant brain tumors. Due to the presence of the blood-brain barrier (BBB), the effectiveness of therapeutics is greatly affected. In this work, to develop an efficient anti-glioma drug with targeting and which was able to cross the BBB, cell-penetrating peptides (R8) and transferrin co-modified doxorubicin (DOX)-loaded liposomes (Tf-LPs) were prepared. Tf-LPs possessed a spherical shape and uniform size with 128.64 nm and their ξ-potential was 6.81 mV. Tf-LPs were found to be stable in serum within 48 h. Uptake of Tf-LPs in both U87 and GL261 cells was analyzed by confocal laser scanning microscopy and by flow cytometry. Tf-LPs were efficiently taken up by both U87 and GL261 cells. Moreover, Tf-LPs exhibited sustained-release. The cumulative release of DOX from Tf-LPs reached ~50.0% and showed excellent anti-glioma efficacy. Histology of major organs, including brain, heart, liver, spleen, lungs and kidney, and the bodyweight of mice, all indicated low toxicity of Tf-LPs. In conclusion, Tf-LPs showed great promise as an anti-glioma therapeutic agent.
Nanobiomaterials Used in Cancer Therapy: An Up-To-Date Overview
Authors: Lungu Iulia Ioana , Grumezescu Alexandru Mihai , Volceanov Adrian , Andronescu Ecaterina
Published: September 2019

The disadvantages that come with traditional cancer treatments, such as chemotherapy and radiotherapy, generated a research shift toward nanotechnology. However, even with the important advancements regarding cancer therapy, there are still serious stepping stones that need to be addressed. The use of both nanotechnology and nanomedicine has generated significant improvements in nano-sized materials development and their use as therapeutic, diagnosis, and imaging agents. The biological barriers that come from the healthy body, as well from the tumorous sites, are important parameters that need to be taken into consideration when designing drug delivery systems. There are several aspects of extreme importance such as the tumor microenvironment and vasculature, the reticuloendothelial system, the blood–brain barrier, the blood–tumor barrier, and the renal system. In order to achieve an effective system for cancer therapy, several characteristics of the nanoparticles have been outlined. Moreover, this review has also focused on the different types of nanoparticles that have been studied over the years as potential candidates for cancer therapy.
A Selective, Dual Emission β-Alanine Aminopeptidase Activated Fluorescent Probe for the Detection of Pseudomonas aeruginosa, Burkholderia cepacia, and Serratia marcescens
Authors: Váradi Linda , Najib Elias Y. , Hibbs David E. , Perry John D. , Groundwater Paul W.
Published: September 2019

Selective detection of β-alanyl aminopeptidase (BAP)-producing Pseudomonas aeruginosa, Serratia marcescens, and Burkholderia cepacia was achieved by employing the blue-to-yellow fluorescent transition of a BAP-specific enzyme substrate, 3-hydroxy-2-(p-dimethylaminophenyl)flavone derivative, incorporating a self-immolative linker to β-alanine. Upon cellular uptake and accumulation of the substrate by viable bacterial colonies, blue fluorescence was generated, while hydrolysis of the N-terminal peptide bond by BAP resulted in the elimination of the self-immolative linker and the restoration of the original fluorescence of the flavone derivative.
Site Selectivity in Pd-Catalyzed Reactions of α-Diazo-α-(methoxycarbonyl)acetamides: Effects of Catalysts and Substrate Substitution in the Synthesis of Oxindoles and β-Lactams
Authors: Solé Daniel , Pérez-Janer Ferran , Amenta Arianna , Bennasar M.-Lluïsa , Fernández Israel
Published: September 2019

The Pd-catalyzed intramolecular carbene C–H insertion of α-diazo-α-(methoxycarbonyl)acetamides to prepare oxindoles as well as β-lactams was studied. In order to identify what factors influence the selectivity of the processes, we explored how the reactions are affected by the catalyst type, using two oxidation states of Pd and a variety of ligands. It was found that, in the synthesis of oxindoles, ((IMes)Pd(NQ))2 can be used as an alternative to Pd2(dba)3 to catalyze the carbene CArsp2–H insertion, although it was less versatile. On the other hand, it was demonstrated that the Csp3–H insertion leading to β-lactams can be effectively promoted by both Pd(0) and Pd(II) catalysts, the latter being most efficient. Insight into the reaction mechanisms involved in these transformations was provided by DFT calculations.
Enlarged Pore Size Chiral Mesoporous Silica Nanoparticles Loaded Poorly Water-Soluble Drug Perform Superior Delivery Effect
Authors: Guo Yingyu , Gou Kaijun , Yang Baixue , Wang Yumei , Pu Xueyu , Li Sanming , Li Heran
Published: September 2019

Large mesopores of chiral silica nanoparticles applied as drug carrier are worth studying. In this study, chiral mesoporous silica nanoparticles (CMSN) and enlarged chiral mesoporous silica nanoparticles (E-CMSN) with a particle size from 200 to 300 nm were synthesized. Fourier transform infrared spectrometer (FTIR), circular dichroism spectrum, scanning electron microscopy (SEM), transmission electron microscope (TEM), and nitrogen adsorption/desorption measurement were adopted to explore their characteristics. The results showed that the surface area, pore volume, and pore diameter of E-CMSN were higher than those of CMSN due to enlarged mesopores. Poorly water-soluble drug nimesulide (NMS) was taken as the model drug and loaded into carriers using adsorption method. After NMS was loaded into CMSN and E-CMSN, most crystalline NMS converted to amorphous phase and E-CMSN was superior. The anti-inflammatory pharmacodynamics and in vivo pharmacokinetics results were consistent with the wetting property and in vitro drug dissolution results, verifying that NMS/E-CMSN exhibited superior NMS delivery system based on its higher oral relative bioavailability and anti-inflammatory effect because its enlarge mesopores contributed to load and release more amorphous NMS. The minor variations in the synthesis process contributed to optimize the chiral nano-silica drug delivery system.
Combining Soft Polysilazanes with Melt-Shear Organization of Core–Shell Particles: On the Road to Polymer-Templated Porous Ceramics
Authors: Boehm Anna K. , Ionescu Emanuel , Koch Marcus , Gallei Markus
Published: September 2019

The preparation of ordered macroporous SiCN ceramics has attracted significant interest and is an attractive area for various applications, e.g., in the fields of catalysis, gas adsorption, or membranes. Non-oxidic ceramics, such as SiCN, own a great stability based on the covalent bonds between the containing elements, which leads to interesting properties concerning resistance and stability at high temperature. Their peculiar properties have become more and more important for a manifold of applications, like catalysis or separation processes, at high temperatures. Within this work, a feasible approach for the preparation of ordered porous materials by taking advantage of polymer-derived ceramics is presented. To gain access to free-standing films consisting of porous ceramic materials, the combination of monodisperse organic polymer-based colloids with diameters of 130 nm and 180 nm featuring a processable preceramic polymer is essential. For this purpose, the tailored design of hybrid organic/inorganic particles featuring anchoring sites for a preceramic polymer in the soft shell material is developed. Moreover, polymer-based core particles are used as sacrificial template for the generation of pores, while the preceramic shell polymer can be converted to the ceramic matrix after thermal treatment. Two different routes for the polymer particles, which can be obtained by emulsion polymerization, are followed for covalently linking the preceramic polysilazane Durazane1800 (Merck, Germany): (i) Free radical polymerization and (ii) atom transfer radical polymerization (ATRP) conditions. These hybrid hard core/soft shell particles can be processed via the so-called melt-shear organization for the one-step preparation of free-standing particle films. A major advantage of this technique is the absence of any solvent or dispersion medium, enabling the core particles to merge into ordered particle stacks based on the soft preceramic shell. Subsequent ceramization of the colloidal crystal films leads to core particle degradation and transformation into porous ceramics with ceramic yields of 18–54%.
6-Shogaol Suppresses 2-Amino-1-Methyl-6-Phenylimidazo [4,5-b] Pyridine (PhIP)-Induced Human 786-O Renal Cell Carcinoma Osteoclastogenic Activity and Metastatic Potential
Authors: Yeh I-Jeng , Chen Szu-Chia , Yen Meng-Chi , Wu Yen-Hung , Hung Chih-Hsing , Kuo Po-Lin
Published: September 2019

2-Amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP) which can be detected in processed meats and red meats, is a potential carcinogen for renal cell carcinoma (RCC). Approximately 30% of patients with metastatic RCC have bone metastases, and the prognosis of RCC with bone metastases is poor. Thus, the aim of the present study was to investigate whether PhIP induced bone metastases and to develop novel therapeutic agents. Our data revealed that PhIP pre-treatment increased the production of parathyroid hormone-related protein (PTHrP) in human 786-O renal cell carcinoma cells. Subsequently, the cultures of human osteoblasts with PhIP-stimulated condition medium of 786-O increased the expression of the macrophage colony-stimulating factor (M-CSF) and receptor activator of nuclear factor kappa-B ligand (RANKL), and decreased the expression of osteoprotegerin (OPG). In addition, PhIP-mediated PTHrP up-regulated as well as increased IL-8 secretion in 786-O cells, and then contributed to 786-O-mediated bone resorption. Furthermore, 6-shogaol, which is an active ingredient in ginger, showed suppressive effects on PhIP-mediated bone resorption. In summary, this is the first study to demonstrate that PhIP pre-treatment increases the stimulatory effect of human renal cell carcinoma 786-O on osteoclastogenesis activity directly by PTHrP. In addition, 6-shogaol treatment reverses PhIP-mediated bone resorption. It suggests that 6-shogaol treatment results in bone resorption activity in the RCC model in vitro.
Protective Effect of Spirulina platensis Extract against Dextran-Sulfate-Sodium-Induced Ulcerative Colitis in Rats
Authors: Morsy Mohamed A. , Gupta Sumeet , Nair Anroop B. , Venugopala Katharigatta N. , Greish Khaled , El-Daly Mahmoud
Published: September 2019

Inflammatory bowel disease is a multifactorial inflammatory condition. This study aimed to test the protective effects of Spirulina platensis against ulcerative colitis (UC). UC was induced in thirty-six male Wistar rats by adding dextran sulfate sodium (DSS) to their drinking water, while a control group received only drinking water. UC rats were equally-divided into six groups that received a single oral daily dose of vehicle (DSS), sulfasalazine (SSZ, 50 mg/kg/day), chloroform or the hydroalcoholic extracts of Spirulina platensis (100 or 200 mg/kg/day) for 15 days, and then blood and colon samples were harvested for determination of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), erythrocyte sedimentation rate (ESR), myeloperoxidase (MPO), and histopathology. At the end of the study, compared to time-matched controls, UC rats showed increased TNF-α (1.64-fold), IL-6 (5.73-fold), ESR (3.18-fold), and MPO (1.61-fold), along with loss of body weight (24.73%) and disease activity index (1.767 ± 0.216 vs. 0 ± 0), p < 0.001. These effects were prevented by SSZ treatment (p < 0.001 vs. DSS). The hydroalcoholic extract of Spirulina platensis dose-dependently modulated all DSS-induced inflammatory changes. However, the chloroform extract significantly lowered only IL-6 and ESR, but not TNF-α or MPO levels. The protective effects of the hydroalcoholic extract of Spirulina platensis against experimental UC involved mitigation of DSS-induced inflammation.
Role of Memory B Cells in Hemagglutinin-Specific Antibody Production Following Human Influenza A Virus Infection
Authors: Sangster Mark Y. , Nguyen Phuong Q. T. , Topham David J.
Published: September 2019

When influenza A virus infects an immune individual, preexisting memory B cell (MBC) activation and rapid anamnestic antibody production plays a key role in viral clearance. The most effective neutralizing antibodies target the antigenically variable head of the viral hemagglutinin (HA); antibodies against the conserved HA stalk provide broader but less potent protection. In this review, we provide a comprehensive picture of an adult’s HA-specific antibody response to influenza virus infection. The process is followed from preexisting HA-specific MBC activation and rapid production of anti-HA antibodies, through to germinal center seeding and adaptation of the response to novel features of the HA. A major focus of the review is the role of competition between preexisting MBCs in determining the character of the HA-reactive antibody response. HA novelty modifies this competition and can shift the response from the immunodominant head to the stalk. We suggest that antibodies resulting from preexisting MBC activation are important regulators of anti-HA antibody production and play a role in positive selection of germinal center B cells reactive to novel HA epitopes. Our review also considers the role of MBCs in the effects of early-life imprinting on HA head- and stalk-specific antibody responses to influenza infection. An understanding of the processes described in this review will guide development of vaccination strategies that provide broadly effective protection.
Preformulation Study of Electrospun Haemanthamine-Loaded Amphiphilic Nanofibers Intended for a Solid Template for Self-Assembled Liposomes
Authors: Viet Nguyen Khan , Laidmäe Ivo , Kogermann Karin , Lust Andres , Meos Andres , Viet Ho Duc , Raal Ain , Heinämäki Jyrki , Thi Nguyen Hoai
Published: September 2019

Haemanthamine (HAE) has been proven as a potential anticancer agent. However, the therapeutic use of this plant-origin alkaloid to date is limited due to the chemical instability and poorly water-soluble characteristics of the agent. To overcome these challenges, we developed novel amphiphilic electrospun nanofibers (NFs) loaded with HAE, phosphatidylcholine (PC) and polyvinylpyrrolidone (PVP), and intended for a stabilizing platform (template) of self-assembled liposomes of the active agent. The NFs were fabricated with a solvent-based electrospinning method. The chemical structure of HAE and the geometric properties, molecular interactions and physical solid-state properties of the NFs were investigated using nuclear magnetic resonance (NMR) spectroscopy, scanning electron microscopy (SEM), photon correlation spectroscopy (PCS), Fourier transform infrared (FTIR) spectroscopy, X-ray powder diffraction (XRPD) and differential scanning calorimetry (DSC), respectively. An in-house dialysis-based dissolution method was used to investigate the drug release in vitro. The HAE-loaded fibers showed a nanoscale size ranging from 197 nm to 534 nm. The liposomes with a diameter between 63 nm and 401 nm were spontaneously formed as the NFs were exposed to water. HAE dispersed inside liposomes showed a tri-modal dissolution behavior. In conclusion, the present amphiphilic NFs loaded with HAE are an alternative approach for the formulation of a liposomal drug delivery system and stabilization of the liposomes of the present alkaloid.
Complex Aerogels Generated from Nano-Polysaccharides and Its Derivatives for Oil–Water Separation
Authors: Yagoub Hajo , Zhu Liping , Shibraen Mahmoud H. M. A. , Altam Ali A. , Babiker Dafaalla M. D. , Liang Songmiao , Jin Yan , Yang Shuguang
Published: September 2019

The complex aerogel generated from nano-polysaccharides, chitin nanocrystals (ChiNC) and TEMPO-oxidized cellulose nanofibers (TCNF), and its derivative cationic guar gum (CGG) is successfully prepared via a facile freeze-drying method with glutaraldehyde (GA) as cross-linkers. The complexation of ChiNC, TCNF, and CGG is shown to be helpful in creating a porous structure in the three-dimensional aerogel, which creates within the aerogel with large pore volume and excellent compressive properties. The ChiNC/TCNF/CGG aerogel is then modified with methyltrichlorosilane (MTCS) to obtain superhydrophobicity/superoleophilicity and used for oil–water separation. The successful modification is demonstrated through FTIR, XPS, and surface wettability studies. A water contact angle of 155° on the aerogel surface and 150° on the surface of the inside part of aerogel are obtained for the MTCS-modified ChiNC/TCNF/CGG aerogel, resulting in its effective absorption of corn oil and organic solvents (toluene, n-hexane, and trichloromethane) from both beneath and at the surface of water with excellent absorption capacity (i.e., 21.9 g/g for trichloromethane). More importantly, the modified aerogel can be used to continuously separate oil from water with the assistance of a vacuum setup and maintains a high absorption capacity after being used for 10 cycles. The as-prepared superhydrophobic/superoleophilic ChiNC/TCNF/CGG aerogel can be used as a promising absorbent material for the removal of oil from aqueous media.
CFD-DEM Modeling and Simulation Coupled to a Global Thermodynamic Analysis Methodology for Evaluating Energy Performance: Biofertilizer Industry
Authors: Burgos-Florez Francisco , Bula Antonio , Marquez John , Ferrer Alberto , Sanjuan Marco
Published: September 2019

This work develops a methodology based on real chemical plant data collected from a Nitrogen-Phosphorus-Potassium fertilizer (NPK) cooling rotary drum. By blending thermodynamic variables given by global energy and mass balances with computational fluid dynamics-discrete element method (CFD-DEM) modeling and simulation, the methodology provides an initial approximation to the understanding of heat transfer inside industry rotary coolers. The NPK cooling process was modeled in CFD software Simcenter STAR − CCM + 13.06.011 using a Eulerian–Lagrangian scheme through a coupled CFD-DEM method using one-way coupling. The average temperature of the NPK particles was obtained as well as the average mass flow of the particles dropping as the drum was rotating. The analysis was performed for two-particle diameters (8 and 20 mm) during 17.5 s. The average heat transfer coefficient between the fluid and the NPK particles during the simulated time was obtained. A thermodynamic analysis was carried out using instantaneous energy and mass balances. Prandtl, Nusselt, and Reynolds numbers were obtained for each simulated time step. Finally, through a non-linear regression using the Marquardt method, a correlation between Prandtl, Nusselt, and Reynolds number was developed that allowed analyzing the rotating drum. Results showed that the proposed methodology could serve as a useful tool during the design and analysis of any given rotary cooler, allowing calculation of the heat transfer coefficient and obtaining the process variables that could expand the machine operational capabilities due to the knowledge of the Nusselt number as a function of the drum working parameters.
Credit Valuation Adjustment Compression by Genetic Optimization
Authors: Chataigner Marc , Crépey Stéphane
Published: September 2019

Since the 2008–2009 financial crisis, banks have introduced a family of X-valuation adjustments (XVAs) to quantify the cost of counterparty risk and of its capital and funding implications. XVAs represent a switch of paradigm in derivative management, from hedging to balance sheet optimization. They reflect market inefficiencies that should be compressed as much as possible. In this work, we present a genetic algorithm applied to the compression of credit valuation adjustment (CVA), the expected cost of client defaults to a bank. The design of the algorithm is fine-tuned to the hybrid structure, both discrete and continuous parameter, of the corresponding high-dimensional and nonconvex optimization problem. To make intensive trade incremental XVA computations practical in real-time as required for XVA compression purposes, we propose an approach that circumvents portfolio revaluation at the cost of disk memory, storing the portfolio exposure of the night so that the exposure of the portfolio augmented by a new deal can be obtained at the cost of computing the exposure of the new deal only. This is illustrated by a CVA compression case study on real swap portfolios.
Three-Fold Urban Expansion in Saudi Arabia from 1992 to 2013 Observed Using Calibrated DMSP-OLS Night-Time Lights Imagery
Authors: Alahmadi Mohammed , Atkinson Peter M.
Published: September 2019

Although Saudi Arabia has experienced very high rates of urbanization, little interest has been given to investigating national and provincial trends in urbanization in space and time. Night-time lights satellite sensor data are considered as a suitable source of imagery for mapping urban areas across large regions. This study uses night-time lights data to analyze the spatial and temporal patterns and dynamics of urban growth in Saudi Arabia between 1992 and 2013 at the national and provincial levels. A hybrid method was applied to ensure the continuity and consistency of the Defense Meteorological Satellite Program (DMSP) Operational Line-Scan System (OLS) of stable night-time (SNT) data through time. As a result of spatial variation in the character of urban areas across Saudi Arabia, different thresholds were used to derive urban areas from the imagery. The extracted urban morphology was assessed using socio-economic data and finer resolution imagery, and accuracy assessment revealed excellent agreement. Based on the rigorous stepwise calibration analysis undertaken here, urban areas in Saudi Arabia were found to have increased three-fold between 1992 and 2013, with most of the increase concentrated in three provinces (Makkah, Riyadh and Eastern). In addition, significant variation was observed in urbanization at the provincial level. The observed high rates of urban growth are aligned with the prosperity and socio-economic development of Saudi Arabia over the last 40 years. The research shows that DMSP-OLS SNT data can provide a valuable source of information for mapping the space–time dynamics of urban growth across very large areas. Such data are required by urban and regional planners, as well as policy makers, for characterizing urban growth patterns, interpreting the drivers of such dynamics and for forecasting future growth, as well as achieving sustainable development management.