bluuebunny/crossref_metadata_2025 huggingface dataset:
Glycosphingolipids Recognized by Acinetobacter baumannii
Authors: Madar Johansson Miralda , Azzouz Mehjar , Häggendal Beatrice , Säljö Karin , Malmi Henri , Zavialov Anton , Teneberg Susann
Published: April 2020

Acinetobacter baumannii is an opportunistic bacterial pathogen associated with hospital-acquired infections, including pneumonia, meningitis, bacteremia, urinary tract infection, and wound infections. Recognition of host cell surface carbohydrates plays a crucial role in adhesion and enables microbes to colonize different host niches. Here the potential glycosphingolipid receptors of A. baumannii were examined by binding of 35S-labeled bacteria to glycosphingolipids on thin-layer chromatograms. Thereby a selective interaction with two non-acid glycosphingolipids of human and rabbit small intestine was found. The binding-active glycosphingolipids were isolated and, on the basis of mass spectrometry, identified as neolactotetraosylceramide (Galβ4GlcNAcβ3Galβ4Glcβ1Cer) and lactotetraosylceramide (Galβ3GlcNAcβ3Galβ4Glcβ1Cer). Further binding assays using reference glycosphingolipids showed that A. baumannii also bound to lactotriaosylceramide (GlcNAcβ3Galβ4Glcβ1Cer) demonstrating that GlcNAc was the basic element recognized. In addition, the bacteria occasionally bound to galactosylceramide, lactosylceramide with phytosphingosine and/or hydroxy fatty acids, isoglobotriaosylceramide, gangliotriaosylceramide, and gangliotetraosylceramide, in analogy with binding patterns that previously have been described for other bacteria classified as “lactosylceramide-binding”. Finally, by isolation and characterization of glycosphingolipids from human skin, the presence of neolactotetraosylceramide was demonstrated in this A. baumannii target tissue.
Fe-Al Phosphate Microcrystals in Pedogenic Goethite Pisoliths
Authors: Kovács János , Farics Éva , Szabó Péter , Sajó István
Published: April 2020

In sedimentary rocks, Fe-Al phosphate minerals occur in different rocks and depositional environments. Herein, we present microcrystals of wavellite, crandallite, and cacoxenite from pedogenic goethite pisoliths and nodules. Pisoliths and nodules are generally dominated by Fe oxides and oxihydroxides. Frequently, pisoliths and nodules demonstrate high phosphatization and a substantial contribution of allogenic detritus. The aim of our study is to present these remarkable crystals found in goethites. We describe the geochemistry and mineralogy of the pisoliths and try to interpret the possible paragenesis of the minerals. Loose ferruginous pisoliths and nodules are separated from the red paleosol and analyzed using field emission scanning electron microscope (FE-SEM) coupled with the energy dispersive X-ray detector (EDS), X-ray fluorescence spectroscopy (XRF), and X-ray powder diffraction (XRD) methods. The studied paleosols are weathered in a subtropical climate and the newly formed precipitation products, such as crandallite, wavellite, cacoxenite, and goethite, accumulate during the weathering of apatite.
Recovery of Germanium from Sulphate Solutions Containing Indium and Tin Using Cementation with Zinc Powder
Authors: Drzazga Michał , Benke Grzegorz , Ciszewski Mateusz , Knapik Magdalena , Radoń Adrian , Kozłowicz Sylwia , Goc Karolina , Kowalik Patrycja , Leszczyńska-Sejda Katarzyna
Published: April 2020

Cementation of germanium from sulphate solution obtained after the leaching of GeIn dross using zinc dust was investigated. The composition of the examined solution was 5.15 Ge, 1.52 In, and 5.81 g/dm3 Zn. In order to resemble the solution before detinning, Sn concentration between 2–10 g/dm3 was also investigated. It was found that >99% of germanium may be precipitated from the solution. In order to achieve high selectivity, a detinned solution should be used because the precipitation yields of germanium and tin from the solution containing Sn were similar. For cementation with Zn powder at 75 °C for 2 h with a final pH of 2.0, over 99% of the germanium was removed from the solution, while the indium precipitation yield was 12%. The obtained cementate contained 50% Ge, mainly in elementary form.
Extra-Framework Content in Sodalite-Group Minerals: Complexity and New Aspects of Its Study Using Infrared and Raman Spectroscopy
Authors: Chukanov Nikita V. , Vigasina Marina F. , Zubkova Natalia V. , Pekov Igor V. , Schäfer Christof , Kasatkin Anatoly V. , Yapaskurt Vasiliy O. , Pushcharovsky Dmitry Yu.
Published: April 2020

Nine samples of carbonate-free sodalite-group minerals, including those with abnormally high contents of polysulfide groups, fluoride anion and carbon dioxide molecules as well as synthetic fluoraluminate sodalite-type compound Na8(Si7Al5O24)(AlF6)3–·5H2O, have been studied by means of electron microprobe analyses, infrared and Raman spectroscopy; the CO2 content was determined using the selective sorption of gaseous ignition products. This article describes a semi-quantitative method for estimating the content of carbon dioxide molecules in these minerals, based on IR spectroscopy data. The data obtained demonstrate the existence of a sulfide sodalite-group mineral with the idealized formula Na7(Si6Al6O24)(S3−)·H2O, which differs significantly from the formula Na6Ca2(Si6Al6O24)S2–2 accepted for lazurite. According to single-crystal X-ray structural analysis, in the F-rich sodalite-group mineral from the Eifel paleovolcanic region, Germany with the idealized formula Na7(Si6Al6O24)F−·nH2O fluorine occurs as an isolated F− anion, unlike synthetic F-rich sodalite-type compounds.
Geochemistry of Rare Earth Elements in Bedrock and Till, Applied in the Context of Mineral Potential in Sweden
Authors: Sadeghi Martiya , Arvanitidis Nikolaos , Ladenberger Anna
Published: April 2020

The Rare Earth Element (REE) mineralizations are not so “rare” in Sweden. They normally occur associated and hosted within granitic crystalline bedrock, and in mineral deposits together with other base and trace metals. Major REE-bearing mineral deposit types are the apatite-iron oxide mineralizations in Norrbotten (e.g., Kiruna) and Bergslagen (e.g., Grängesberg) ore regions, the various skarn deposits in Bergslagen (e.g., Riddarhyttan-Norberg belt), hydrothermal deposits (e.g., Olserum, Bastnäs) and alkaline-carbonatite intrusions such as the Norra Kärr complex and Alnö. In this study, analytical data of samples collected from REE mineralizations during the EURARE project are compared with bedrock and till REE geochemistry, both sourced from databases available at the Geological Survey of Sweden. The positive correlation between REE composition in the three geochemical data groups allows better understanding of REE distribution in Sweden, their regional discrimination, and genetic classification. Data provides complementary information about correlation of LREE and HREE in till with REE content in bedrock and mineralization. Application of principal component analysis enables classification of REE mineralizations in relation to their host. These results are useful in the assessment of REE mineral potential in areas where REE mineralizations are poorly explored or even undiscovered.
Genesis of Early–Middle Jurassic Intrusive Rocks in the Erguna Block (NE China) in Response to the Late-Stage Southward Subduction of the Mongol–Okhotsk Oceanic Plate: Constraints from Geochemistry and Zircon U–Pb Geochronology and Lu–Hf Isotopes
Authors: Mao Anqi , Sun Deyou , Gou Jun , Zheng Han
Published: April 2020

The subduction processes and geodynamic scenarios of the late-stage southward subduction of the Mongol–Okhotsk oceanic slab since the Early Jurassic are subjects of great debate. This contribution presents new U–Pb zircon dating, trace element geochemistry, Ti-in zircon geothermometry, and Lu–Hf isotopes of zircon, as well as bulk-rock geochemical data for Early–Middle Jurassic intrusive rocks in the Erguna Block, NE China. Approximately 181–198 Ma monzogranites and ca. 162–174 Ma quartz monzonites were identified in the block. The Early Jurassic monzogranites are high-K calc-alkaline I-type granites, which display moderately concave-upward rare earth element (REE) patterns with slightly negative Eu anomalies, and low zircon crystallization temperatures. The Middle Jurassic quartz monzonites have low Yb and Y concentrations, high Sr/Y ratios, and strong high field strength elements (HFSEs) depletions, that are in excellent agreement with adakitic rocks. They exhibit right-sloping REE patterns with negligible Eu anomalies, and a wide range of zircon crystallization temperatures. The intrusions yield εHf(t) values between −4.1 to +4.8 and juvenile two-stage model (TDM2) ages varying from 918–1488 Ma. The geochemical and isotopic signatures suggest that the monzogranites were likely derived by the partial melting of K-rich meta-basalts within the lower part of a juvenile crust that had medium-thickness (≤40 km), with the involvement of minor mantle materials. Whereas, the quartz monzonites were possibly produced by partial melting of a thickened continental lower crust (≥50 km). The Mongol–Okhotsk tectonic regime played a dominant role in accounting for their formation. An Andean-type continental arc setting was developed during the Early–Middle Jurassic, with gradual thickening of the continental crust. The significant crustal thickening may reach its ultimate stage at ca. 162–174 Ma, which marks the tectonic transition from compression to extension. The southward subduction beneath the Erguna Block was continuous and stable during the Early Jurassic. Rollback of the subducted slab occurred at ca. 174–177 Ma, followed by moderate magmatic activities represented by adakitic rocks.
Biochar from Fique Bagasse for Remotion of Caffeine and Diclofenac from Aqueous Solution
Authors: Correa-Navarro Yaned Milena , Giraldo Liliana , Moreno-Piraján Juan Carlos
Published: April 2020

Caffeine and diclofenac are molecules with high human intake, and both belong to the ‘emergent’ class of contaminants. These compounds have been found at different concentrations in many sources of water worldwide and have several negative impacts on aquatic life systems; that is why the search for new alternatives for their removal from aqueous media is of transcendental importance. In this sense, adsorption processes are an option to attack this problem and for this reason, biochar could be a good alternative. In this regard, were prepared six different biochar from fique bagasse (FB), a useless agroindustry by-product from fique processing. The six biochar preparations were characterized through several physicochemical procedures, while for the adsorption processes, pH, adsorption time and concentration of caffeine and diclofenac were evaluated. Results showed that the biochar obtained by pyrolysis at 850 °C and residence time of 3 h, labeled as FB850-3, was the material with the highest adsorbent capacity with values of 40.2 mg g−1 and 5.40 mg g−1 for caffeine and diclofenac, respectively. It was also shown that the experimental data from FB850-3 fitted very well the Redlich–Peterson isotherm model and followed a pseudo-first and pseudo-second-order kinetic for caffeine and diclofenac, respectively.
In Situ Raman Investigation of TiO2 Nanotube Array-Based Ultraviolet Photodetectors: Effects of Nanotube Length
Authors: Ren Yanyu , Shi Xiumin , Xia Pengcheng , Li Shuang , Lv Mingyang , Wang Yunxin , Mao Zhu
Published: April 2020

TiO2 nanotube arrays (TNAs) with tube lengths of 4, 6, and 7 μm were prepared via two-step anodization. Thereafter, ultraviolet (UV) photodetectors (PDs) with Au/TiO2/Au structures were prepared using these TNAs with different tube lengths. The effects of TNA length and device area on the performance of the device were investigated using in situ Raman spectroscopy. The maximum laser/dark current ratio was achieved by using a TNA with a size of 1 × 1 cm2 and a length of 7 μm, under a 532 nm laser. In addition, when the device was irradiated with a higher energy laser (325 nm), the UV Raman spectrum was found to be more sensitive than the visible Raman spectrum. At 325 nm, the laser/dark current ratio was nearly 24 times higher than that under a 532 nm laser. Six phonon modes of anatase TNAs were observed, at 144, 199, 395, 514, and 635 cm−1, which were assigned to the Eg(1), Eg(2), B1g(1), A1g/B1g(2), and Eg(3) modes, respectively. The strong low-frequency band at 144 cm−1 was caused by the O-Ti-O bending vibration and is a characteristic band of anatase. The results show that the performance of TNA-based PDs is length-dependent. Surface-enhanced Raman scattering signals of 4-mercaptobenzoic acid (4-MBA) molecules were also observed on the TNA surface. This result indicates that the length-dependent performance may be derived from an increase in the specific surface area of the TNA. In addition, the strong absorption of UV light by the TNAs caused a blueshift of the Eg(1) mode.
Riley Oxidation of Heterocyclic Intermediates on Paths to Hydroporphyrins—A Review
Authors: Wang Pengzhi , Lindsey Jonathan S.
Published: April 2020

Riley oxidation of advanced heterocyclic intermediates (dihydrodipyrrins and tetrahydrodipyrrins) is pivotal in routes to synthetic hydroporphyrins including chlorins, bacteriochlorins, and model (bacterio)chlorophylls. Such macrocycles find wide use in studies ranging from energy sciences to photomedicine. The key transformation (–CH3 → –CHO) is often inefficient, however, thereby crimping the synthesis of hydroporphyrins. The first part of the review summarizes 12 representative conditions for Riley oxidation across diverse (non-hydrodipyrrin) substrates. An interlude summarizes the proposed mechanisms and provides context concerning the nature of various selenium species other than SeO2. The second part of the review comprehensively reports the conditions and results upon Riley oxidation of 45 1-methyltetrahydrodipyrrins and 1-methyldihydrodipyrrins. A comparison of the results provides insights into the tolerable structural features for Riley oxidation of hydrodipyrrins. In general, Riley oxidation of dihydrodipyrrins has a broad scope toward substituents, but proceeds in only modest yield. Too few tetrahydrodipyrrins have been examined to draw conclusions concerning scope. New reaction conditions or approaches will be required to achieve high yields for this critical transformation in the synthesis of hydroporphyrins.
Easy Ligand Activation in the Coordination Sphere of Ru inside the [PW11O39]7– Backbone
Authors: Mukhacheva Anna A. , Gushchin Artem L. , Yanshole Vadim V. , Abramov Pavel A. , Sokolov Maksim N.
Published: April 2020

Irradiation of the Keggin-type [PW11O39{Ru(NO)}]4− (Ru-NO) polyoxometalate in CH3CN results in rapid NO ligand elimination with the formation of [PW11O39{RuIII(CH3CN)}]4− (Ru-CH3CN). This complex offers an easy entry into the Ru-based chemistry of the {PW11Ru} complex. Attempts to substitute N3− for CH3CN in the presence of an NaN3 excess lead a variety of products: (i) [PW11O39{RuIII(N3)}]4− (Ru-N3); (ii) [PW11O39{RuIII(N4HC-CH3)}]4− (Ru-Tz) as a click-reaction product; and (iii) [PW11O39{RuII(N2)}]5− (Ru-N2). UV-VIS, CV, and HR-ESI-MS techniques were used for the reaction monitoring and characterization of the products.
Manipulation of the Size and Phase Composition of Yttrium Iron Garnet Nanoparticles by Pulsed Laser Post-Processing in Liquid
Authors: Hupfeld Tim , Stein Frederic , Barcikowski Stephan , Gökce Bilal , Wiedwald Ulf
Published: April 2020

Modification of the size and phase composition of magnetic oxide nanomaterials dispersed in liquids by laser synthesis and processing of colloids has high implications for applications in biomedicine, catalysis and for nanoparticle-polymer composites. Controlling these properties for ternary oxides, however, is challenging with typical additives like salts and ligands and can lead to unwanted byproducts and various phases. In our study, we demonstrate how additive-free pulsed laser post-processing (LPP) of colloidal yttrium iron oxide nanoparticles using high repetition rates and power at 355 nm laser wavelength can be used for phase transformation and phase purification of the garnet structure by variation of the laser fluence as well as the applied energy dose. Furthermore, LPP allows particle size modification between 5 nm (ps laser) and 20 nm (ns laser) and significant increase of the monodispersity. Resulting colloidal nanoparticles are investigated regarding their size, structure and temperature-dependent magnetic properties.
Biphasic Computational Fluid Dynamics Modelling of the Mixture in an Agricultural Sprayer Tank
Authors: Badules Jorge , Vidal Mariano , Boné Antonio , Gil Emilio , García-Ramos F. Javier
Published: April 2020

Agitation inside agricultural sprayer tanks can be studied while using an international standard procedure, based on obtaining internal samples of liquid. However, in practice, this test is not easy to perform. Herein, we propose the explicit study of the mixing procedure with biphasic computer simulations using Computational Fluid Dynamics (CFD). An experimental test was performed on a 3000 L tank of a commercial air-assisted sprayer, with two different agitation system configurations, in order to compare the results of several theoretical physical models of biphasic flows for CFD, both Eulerian and Lagrangian. From the analysis of these theoretical models, we conclude that the Volume of Fluid model is not viable and the Discrete Phase Model produces erroneous results, while the Eulerian and Mixture models can both be useful. However, the results obtained suggest that complex streams generated by real-world agitation systems produce more errors in calculations. Both models can be conducted in the design phase, prior to the implementation of the machine. In addition, the computer simulations allow for researchers to analyse the mixing process in detail, making it possible to evaluate the efficiency of an agitation system according to the time that is required to reach mixture homogeneity.
Liposome Drug Delivery System across Endothelial Plasma Membrane: Role of Distance between Endothelial Cells and Blood Flow Rate
Authors: Glukhova Olga E.
Published: April 2020

This paper discusses specific features of the interactions of small-diameter liposomes with the cytoplasmic membrane of endothelial cells using in silico methods. The movement pattern of the liposomal drug delivery system was modeled in accordance with the conditions of the near-wall layer of blood flow. Our simulation results show that the liposomes can become stuck in the intercellular gaps and even break down when the gap is reduced. Liposomes stuck in the gaps are capable of withstanding a shell deformation of ~15% with an increase in liposome energy by 26%. Critical deformation of the membrane gives an impetus to drug release from the liposome outward. We found that the liposomes moving in the near-wall layer of blood flow inevitably stick to the membrane. Liposome sticking on the membrane is accompanied by its gradual splicing with the membrane bilayer. This leads to a gradual drug release inside the cell.
Trimeric Small Interfering RNAs and Their Cholesterol-Containing Conjugates Exhibit Improved Accumulation in Tumors, but Dramatically Reduced Silencing Activity
Authors: Chernikov Ivan V. , Gladkikh Daniil V. , Karelina Ulyana A. , Meschaninova Mariya I. , Ven’yaminova Alya G. , Vlassov Valentin V. , Chernolovskaya Elena L.
Published: April 2020

Cholesterol derivatives of nuclease-resistant, anti-MDR1 small-interfering RNAs were designed to contain a 2’-OMe-modified 21-bp siRNA and a 63-bp TsiRNA in order to investigate their accumulation and silencing activity in vitro and in vivo. The results showed that increasing the length of the RNA duplex in such a conjugate increases its biological activity when delivered using a transfection agent. However, the efficiency of accumulation in human drug-resistant KB-8-5 cells during delivery in vitro in a carrier-free mode was reduced as well as efficiency of target gene silencing. TsiRNAs demonstrated a similar biodistribution in KB-8-5 xenograft tumor-bearing SCID mice with more efficient accumulation in organs and tumors than cholesterol-conjugated canonical siRNAs; however, this accumulation did not provide a silencing effect. The lack of correlation between the accumulation in the organ and the silencing activity of cholesterol conjugates of siRNAs of different lengths can be attributed to the fact that trimeric Ch-TsiRNA lags mainly in the intercellular space and does not penetrate sufficiently into the cytoplasm of the cell. Increased accumulation in the organs and in the tumor, by itself, shows that using siRNA with increased molecular weight is an effective approach to control biodistribution and delivery to the target organ.
Valorization of Yarrow (Achillea millefolium L.) By-Product through Application of Subcritical Water Extraction
Authors: Vladić Jelena , Jakovljević Martina , Molnar Maja , Vidović Senka , Tomić Milan , Drinić Zorica , Jokić Stela
Published: April 2020

In the present study, valorization of yarrow (Achillea millefolium) by-product from the filter tea industry was investigated through the application of subcritical water for the extraction of bioactive compounds. The influence of different process parameters (temperature 120–200 °C, extraction time 10–30 min, and HCl concentration in extraction solvent 0–1.5%) on extract quality in terms of content of bioactive compounds and antioxidant activity was investigated. Optimal conditions of the extraction process (temperature 198 °C, extraction time 16.5 min, and without acidifer) were determined and, when applied, the most efficient exploitation of by-products is achieved, that is, attainment of extracts rich in total phenols and flavonoids and high antioxidant activity. In addition, by applying the high performance liquid chromatographic analysis, the content of chlorogenic acid was determined as well as the hydroxymethylfurfural content in obtained extracts. The results demonstrated that subcritical water can be successfully used for utilization of yarrow by-products for obtaining extracts rich in antioxidants.
Butein Promotes Lineage Commitment of Bone Marrow-Derived Stem Cells into Osteoblasts via Modulating ERK1/2 Signaling Pathways
Authors: Abdallah Basem M. , Ali Enas M.
Published: April 2020

Butein is a phytochemical that belongs to the chalcone family of flavonoids and has antitumor, anti-inflammatory, and anti-osteoclastic bone resorption activities. This study aims to investigate the effects of butein on the differentiation potential of mouse primary bone marrow-derived mesenchymal stem cells (mBMSCs) into osteoblast and adipocyte lineages. Primary cultures of mBMSCs are treated with different doses of butein during its differentiation. Osteoblast differentiation is assessed by alkaline phosphatase (ALP) activity quantification and Alizarin red staining for matrix mineralization, while adipogenesis is assessed by quantification of lipid accumulation using Oil Red O staining. Osteoblastic and adipocytic gene expression markers are determined by quantitative real-time PCR (qPCR). Western blot analysis is used to study the activation of extracellular signal-regulated kinase (ERK1/2). Interestingly, butein promotes the lineage commitment of mBMSCs into osteoblasts, while suppressing their differentiation into adipocytes in a dose-dependent manner. A similar effect of butein is confirmed in human (h) primary BMSCs. Occurring at the molecular level, butein significantly upregulates the mRNA expression of osteoblast-related genes, while downregulating the expression of adipocyte-related genes. The mechanism of butein-induced osteogenesis is found to be mediated by activating the ERK1/2 signaling pathway. To conclude, we identify butein as a novel nutraceutical compound with an osteo-anabolic activity to promote the lineage commitment of BMSCs into osteoblast versus adipocyte. Thus, butein can be a plausible therapeutic drug for enhancing bone formation in osteoporotic patients.
Synthesis, Docking, and In Vitro Anticoagulant Activity Assay of Hybrid Derivatives of Pyrrolo[3,2,1-ij]Quinolin-2(1H)-one as New Inhibitors of Factor Xa and Factor XIa
Authors: Novichikhina Nadezhda , Ilin Ivan , Tashchilova Anna , Sulimov Alexey , Kutov Danil , Ledenyova Irina , Krysin Mikhail , Shikhaliev Khidmet , Gantseva Anna , Gantseva Ekaterina , Podoplelova Nadezhda , Sulimov Vladimir
Published: April 2020

Coagulation factor Xa and factor XIa are proven to be convenient and crucial protein targets for treatment for thrombotic disorders and thereby their inhibitors can serve as effective anticoagulant drugs. In the present work, we focused on the structure–activity relationships of derivatives of pyrrolo[3,2,1-ij]quinolin-2(1H)-one and an evaluation of their activity against factor Xa and factor XIa. For this, docking-guided synthesis of nine compounds based on pyrrolo[3,2,1-ij]quinolin-2(1H)-one was carried out. For the synthesis of new hybrid hydropyrrolo[3,2,1-ij]quinolin-2(1H)-one derivatives, we used convenient structural modification of both the tetrahydro- and dihydroquinoline moiety by varying the substituents at the C6,8,9 positions. In vitro testing revealed that four derivatives were able to inhibit both coagulation factors and three compounds were selective factor XIa inhibitors. An IC50 value of 3.68 μM for was found for the best factor Xa inhibitor and 2 μM for the best factor XIa inhibitor.
Erratum: Panda, S.K., et al., Large-Scale Screening of Ethnomedicinal Plants for Identification of Potential Antibacterial Compounds. Molecules 2016, 21, 293
Authors: Panda Sujogya Kumar , Mohanta Yugal Kishore , Padhi Laxmipriya , Park Young-Hwan , Mohanta Tapan Kumar , Bae Hanhong
Published: April 2020

The authors wish to make the following corrections to their paper [...]
An Oxalate-Bridged Copper(II) Complex Combining Monodentate Benzoate, 2,2′-bipyridine and Aqua Ligands: Synthesis, Crystal Structure and Investigation of Magnetic Properties
Authors: Santana Francielli Sousa , Briganti Matteo , Cassaro Rafael A. Allão , Totti Federico , Ribeiro Ronny Rocha , Hughes David L. , Nunes Giovana Gioppo , Reis Dayane Mey
Published: April 2020

A dinuclear copper(II) complex of formula [{Cu(bipy)(bzt)(OH2)}2(μ-ox)] (1) (where bipy = 2,2′-bipyridine, bzt = benzoate and ox = oxalate) was synthesised and characterised by diffractometric (powder and single-crystal XRD) and thermogravimetric (TG/DTG) analyses, spectroscopic techniques (IR, Raman, electron paramagnetic resonance spectroscopy (EPR) and electronic spectroscopy), magnetic measurements and density functional theory (DFT) calculations. The analysis of the crystal structure revealed that the oxalate ligand is in bis(bidentate) coordination mode between two copper(II) centres. The other four positions of the coordination environment of the copper(II) ion are occupied by one water molecule, a bidentate bipy and a monodentate bzt ligand. An inversion centre located on the ox ligand generates the other half of the dinuclear complex. Intermolecular hydrogen bonds and π-π interactions are responsible for the organisation of the molecules in the solid state. Molar magnetic susceptibility and field dependence magnetisation studies evidenced a weak intramolecular–ferromagnetic interaction (J = +2.9 cm−1) between the metal ions. The sign and magnitude of the calculated J value by density functional theory (DFT) are in agreement with the experimental data.
Experimental and Computational Studies Unraveling the Peculiarity of Enolizable Oxoesters in the Organocatalyzed Mannich-Type Addition to Cyclic N-Acyl Iminium Ions
Authors: Menichetti Andrea , Di Pietro Sebastiano , Di Bussolo Valeria , Favero Lucilla , Pineschi Mauro
Published: April 2020

γ− and δ-Oxoesters are easily available starting materials that have been sparingly used in some organocatalyzed reactions proceeding with a high enantioselectivity. In our experimentation we found that the use of these compounds as the enolizable (nucleophilic) component in organocatalyzed Mannich-type reactions using in situ-generated cyclic N-acyl iminium ions gave low diastereoselectivity and low to moderate values of enantioselectivity. This significant drop of facial selectivity with respect to simple aliphatic aldehydes has been rationalized by means of density functional theory (DFT) calculations.
Recent Advances in the Stereoselective Total Synthesis of Natural Pyranones Having Long Side Chains
Authors: Avula Satya Kumar , Das Biswanath , Csuk Rene , Al-Rawahi Ahmed , Al-Harrasi Ahmed
Published: April 2020

Pyranone natural products have attracted great attention in recent years from chemists and biologists due to their fascinating stereoisomeric structural features and impressive bioactivities. A large number of stereoselective total syntheses of these compounds have been described in the literature. The natural pyranones with long side chains have recently received significant importance in the synthetic field. In the present article, we aim to review the modern progress of the stereoselective total syntheses of these natural pyranones containing long-chain substituents.
H/D Isotope Effects on 1H-NMR Chemical Shifts in Cyclic Heterodimers and Heterotrimers of Phosphinic and Phosphoric Acids
Authors: Mulloyarova Valeriia V. , Ustimchuk Daria O. , Filarowski Aleksander , Tolstoy Peter M.
Published: April 2020

Hydrogen-bonded heterocomplexes formed by POOH-containing acids (diphenylphosphoric 1, dimethylphosphoric 2, diphenylphosphinic 3, and dimethylphosphinic 4) are studied by the low-temperature (100 K) 1H-NMR and 31P-NMR using liquefied gases CDF3/CDF2Cl as a solvent. Formation of cyclic dimers and cyclic trimers consisting of molecules of two different acids is confirmed by the analysis of vicinal H/D isotope effects (changes in the bridging proton chemical shift, δH, after the deuteration of a neighboring H-bond). Acids 1 and 4 (or 1 and 3) form heterotrimers with very strong (short) H-bonds (δH ca. 17 ppm). While in the case of all heterotrimers the H-bonds are cyclically arranged head-to-tail, ···O=P–O–H···O=P–O–H···, and thus their cooperative coupling is expected, the signs of vicinal H/D isotope effects indicate an effective anticooperativity, presumably due to steric factors: when one of the H-bonds is elongated upon deuteration, the structure of the heterotrimer adjusts by shortening the neighboring hydrogen bonds. We also demonstrate the formation of cyclic tetramers: in the case of acids 1 and 4 the structure has alternating molecules of 1 and 4 in the cycle, while in case of acids 1 and 3 the cycle has two molecules of 1 followed by two molecules of 3.
Organic Salts of Pharmaceutical Impurity p-Aminophenol
Authors: Khandavilli U. B. Rao , Keshavarz Leila , Skořepová Eliška , Steendam René R. E. , Frawley Patrick J.
Published: April 2020

The presence of impurities can drastically affect the efficacy and safety of pharmaceutical entities. p-Aminophenol (PAP) is one of the main impurities of paracetamol (PA) that can potentially show toxic effects such as maternal toxicity and nephrotoxicity. The removal of PAP from PA is challenging and difficult to achieve through regular crystallization approaches. In this regard, we report four new salts of PAP with salicylic acid (SA), oxalic acid (OX), l-tartaric acid (TA), and (1S)-(+)-10-camphorsulfonic acid (CSA). All the PAP salts were analyzed using single-crystal X-ray diffraction, powder X-ray diffraction, infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. The presence of minute amounts of PAP in paracetamol solids gives a dark color to the product that was difficult to remove through crystallization. In our study, we found that the addition of small quantities of the aforementioned acids helps to remove PAP from PA during the filtration and washings. This shows that salt formation could be used to efficiently remove challenging impurities.
Co-Loaded Curcumin and Methotrexate Nanocapsules Enhance Cytotoxicity against Non-Small-Cell Lung Cancer Cells
Authors: Rudnik Loanda Aparecida Cabral , Farago Paulo Vitor , Manfron Budel Jane , Lyra Amanda , Barboza Fernanda Malaquias , Klein Traudi , Kanunfre Carla Cristine , Nadal Jessica Mendes , Bandéca Matheus Coelho , Raman Vijayasankar , Novatski Andressa , Loguércio Alessandro Dourado , Zanin Sandra Maria Warumby
Published: April 2020

Background: As part of the efforts to find natural alternatives for cancer treatment and to overcome the barriers of cellular resistance to chemotherapeutic agents, polymeric nanocapsules containing curcumin and/or methotrexate were prepared by an interfacial deposition of preformed polymer method. Methods: Physicochemical properties, drug release experiments and in vitro cytotoxicity of these nanocapsules were performed against the Calu-3 lung cancer cell line. Results: The colloidal suspensions of nanocapsules showed suitable size (287 to 325 nm), negative charge (−33 to −41 mV) and high encapsulation efficiency (82.4 to 99.4%). Spherical particles at nanoscale dimensions were observed by scanning electron microscopy. X-ray diffraction analysis indicated that nanocapsules exhibited a non-crystalline pattern with a remarkable decrease of crystalline peaks of the raw materials. Fourier-transform infrared spectra demonstrated no chemical bond between the drug(s) and polymers. Drug release experiments evidenced a controlled release pattern with no burst effect for nanocapsules containing curcumin and/or methotrexate. The nanoformulation containing curcumin and methotrexate (NCUR/MTX-2) statistically decreased the cell viability of Calu-3. The fluorescence and morphological analyses presented a predominance of early apoptosis and late apoptosis as the main death mechanisms for Calu-3. Conclusions: Curcumin and methotrexate co-loaded nanocapsules can be further used as a novel therapeutic strategy for treating non-small-cell lung cancer.
Solvent Switched Weak Interaction of a 4-Quinazolinone with a Cavitand Derivative
Authors: Nagymihály Zoltán , Lemli Beáta , Kollár László , Kunsági-Máté Sándor
Published: April 2020

Interaction of 4-quinazolinone with tetrakis (3,5-dicarboxylatophenoxy)-cavitand derivative has been studied in methanol and dimethylformamide media using fluorescence spectroscopy and molecular modeling methods. Results show temperature dependent complex formation: either the entropy gain or the high enthalpy changes are responsible for the formation of stable complexes in two separated temperature regions. However, different thermodynamic parameters are associated to different conformations of the complexes: while the high entropy gain associated to the formation of deeply included guest in methanol, the high entropy gain is associated with the formation of weakly included guest in dimethylformamide solvent. This finding highlights the importance of dynamic properties of the species interacted in different solvents.
Fast Identification and Quantification of Graphene Oxide in Aqueous Environment by Raman Spectroscopy
Authors: Yang Shengnan , Chen Qian , Shi Mengyao , Zhang Qiangqiang , Lan Suke , Maimaiti Tusunniyaze , Li Qun , Ouyang Peng , Tang Kexin , Yang Sheng-Tao
Published: April 2020

Today, graphene nanomaterials are produced on a large-scale and applied in various areas. The toxicity and hazards of graphene materials have aroused great concerns, in which the detection and quantification of graphene are essential for environmental risk evaluations. In this study, we developed a fast identification and quantification method for graphene oxide (GO) in aqueous environments using Raman spectroscopy. GO was chemically reduced by hydrazine hydrate to form partially reduced GO (PRGO), where the fluorescence from GO was largely reduced, and the Raman signals (G band and D band) were dominating. According to the Raman characteristics, GO was easily be distinguished from other carbon nanomaterials in aqueous environments, such as carbon nanotubes, fullerene and carbon nanoparticles. The GO concentration was quantified in the range of 0.001–0.6 mg/mL with good linearity. Using our technique, we did not find any GO in local water samples. The transport of GO dispersion in quartz sands was successfully quantified. Our results indicated that GO was conveniently quantified by Raman spectroscopy after partial reduction. The potential applications of our technique in the environmental risk evaluations of graphene materials are discussed further.
Down-Shifting and Anti-Reflection Effect of CsPbBr3 Quantum Dots/Multicrystalline Silicon Hybrid Structures for Enhanced Photovoltaic Properties
Authors: Cao Yunqing , Wu Dong , Zhu Ping , Shan Dan , Zeng Xianghua , Xu Jun
Published: April 2020

Over the past couple of decades, extensive research has been conducted on silicon (Si) based solar cells, whose power conversion efficiency (PCE) still has limitations because of a mismatched solar spectrum. Recently, a down-shifting effect has provided a new way to improve cell performances by converting ultraviolet (UV) photons to visible light. In this work, caesium lead bromide perovskite quantum dots (CsPbBr3 QDs) are synthesized with a uniform size of 10 nm. Exhibiting strong absorption of near UV light and intense photoluminescence (PL) peak at 515 nm, CsPbBr3 QDs show a potential application of the down-shifting effect. CsPbBr3 QDs/multicrystalline silicon (mc-Si) hybrid structured solar cells are fabricated and systematically studied. Compared with mc-Si solar cells, CsPbBr3 QDs/mc-Si solar cells have obvious improvement in external quantum efficiency (EQE) within the wavelength ranges of both 300 to 500 nm and 700 to 1100 nm, which can be attributed to the down-shifting effect and the anti-reflection property of CsPbBr3 QDs through the formation of CsPbBr3 QDs/mc-Si structures. Furthermore, a detailed discussion of contact resistance and interface defects is provided. As a result, the coated CsPbBr3 QDs are optimized to be two layers and the solar cell exhibits a highest PCE of 14.52%.
Surface-Enhanced Raman Scattering and Fluorescence on Gold Nanogratings
Authors: Chang Yu-Chung , Huang Bo-Han , Lin Tsung-Hsien
Published: April 2020

Surface-enhanced Raman scattering (SERS) spectroscopy is a sensitive sensing technique. It is desirable to have an easy method to produce SERS-active substrate with reproducible and robust signals. We propose a simple method to fabricate SERS-active substrates with high structural homogeneity and signal reproducibility using electron beam (E-beam) lithography without the problematic photoresist (PR) lift-off process. The substrate was fabricated by using E-beam to define nanograting patterns on the photoresist and subsequently coat a layer of gold thin film on top of it. Efficient and stable SERS signals were observed on the substrates. In order to investigate the enhancement mechanism, we compared the signals from this substrate with those with photoresist lifted-off, which are essentially discontinuous gold stripes. While both structures showed significant grating-period-dependent fluorescence enhancement, no SERS signal was observed on the photoresist lifted-off gratings. Only transverse magnetic (TM)-polarized excitation exhibited strong enhancement, which revealed its plasmonic attribution. The fluorescence enhancement showed distinct periodic dependence for the two structures, which is due to the different enhancement mechanism. We demonstrate using this substrate for specific protein binding detection. Similar periodicity dependence was observed. Detailed theoretical and experimental studies were performed to investigate the observed phenomena. We conclude that the excitation of surface plasmon polaritons on the continuous gold thin film is essential for the stable and efficient SERS effects.
Tumor-Targeted Delivery of the p53-Activating Peptide VIP116 with PEG-Stabilized Lipodisks
Authors: Lundsten Sara , Hernández Víctor Agmo , Gedda Lars , Sarén Tina , Brown Christopher J. , Lane David P. , Edwards Katarina , Nestor Marika
Published: April 2020

Stapled peptides targeting the interaction between p53 and its negative regulators MDM2 and MDM4 have exhibited great potential as anti-cancer drugs, albeit with room for improvement in formulation and tumor specificity. Lipid bilayer disks (lipodisks) have emerged as promising drug nanocarriers and can by attachment of targeting moieties be directed selectively towards tumor cells. Tumor-targeted delivery of stapled peptides by use of lipodisks may therefore increase the uptake in the tumors and limit toxicity in healthy tissue. Here, we utilized epidermal growth factor receptor (EGFR)-targeted lipodisks to deliver p53-activating stapled peptide VIP116 to EGFR-expressing tumor cells. We demonstrate that VIP116 can be stably formulated in lipodisks (maximum peptide/lipid molar ratio 0.11). In vitro cell studies verify specific binding of EGF-decorated lipodisks to tumor cells and confirm that targeted delivery of VIP116 significantly decreases tumor cell viability.
Cerium Dioxide Nanoparticles as Smart Carriers for Self-Healing Coatings
Authors: Habib Sehrish , Fayyad Eman , Nawaz Muddasir , Khan Adnan , Shakoor Rana A. , Kahraman Ramazan , Abdullah Aboubakr
Published: April 2020

The utilization of self-healing cerium dioxide nanoparticles (CeO2), modified with organic corrosion inhibitors (dodecylamine (DDA) and n-methylthiourea (NMTU)), in epoxy coating is an efficient strategy for enhancing the protection of the epoxy coating and increasing its lifetime. Fourier transform infrared (FTIR) spectroscopy analysis was used to confirm the loading and presence of inhibitors in the nanoparticles. Thermal gravimetric analysis (TGA) measurement studies revealed the amount of 25% and 29.75% w/w for NMTU and DDA in the nanoparticles, respectively. The pH sensitive and self-release behavior of modified CeO2 nanoparticles is confirmed through UV-vis spectroscopy and Zeta potential. It was observed, through scanning electron microscopy (SEM), that a protective layer had been formed on the defect site separating the steel surface from the external environment and healed the artificially created scratch. This protective film played a vital role in the corrosion inhibition of steel by preventing the aggressiveness of Cl− in the solution. Electrochemical impedance spectroscopy (EIS) measurements exhibited the exceptional corrosion inhibition efficiency, reaching 99.8% and 95.7% for the modified coating with DDA and NMTU, respectively, after five days of immersion time.
Grafting Thin Layered Graphene Oxide onto the Surface of Nonwoven/PVDF-PAA Composite Membrane for Efficient Dye and Macromolecule Separations
Authors: Baskoro Febri , Rajesh Kumar Selvaraj , Jessie Lue Shingjiang
Published: April 2020

This study investigates the permeance and rejection efficiencies of different dyes (Rhodamine B and methyl orange), folic acid and a protein (bovine serum albumin) using graphene oxide composite membrane. The ultrathin separation layer of graphene oxide (thickness of 380 nm) was successfully deposited onto porous polyvinylidene fluoride-polyacrylic acid intermediate layer on nonwoven support layer using vacuum filtration. The graphene oxide addition in the composite membrane caused an increased hydrophilicity and negative surface charge than those of the membrane without graphene oxide. In the filtration process using a graphene oxide composite membrane, the permeance values of pure water, dyes, folic acid and bovine serum albumin molecules were more severely decreased (by two orders of magnitude) than those of the nonwoven/polyvinylidene fluoride-polyacrylic acid composite membrane. However, the rejection efficiency of the graphene oxide composite was significantly improved in cationic Rhodamine B (from 9% to 80.3%) and anionic methyl orange (from 28.3% to 86.6%) feed solutions. The folic acid and bovine serum albumin were nearly completely rejected from solutions using either nonwoven/polyvinylidene fluoride-polyacrylic acid or nonwoven/polyvinylidene fluoride-polyacrylic acid/graphene oxide composite membrane, but the latter possessed anti-fouling property against the protein molecules. The separation mechanism in nonwoven/polyvinylidene fluoride-polyacrylic acid membrane includes the Donnan exclusion effect (for smaller-than-pore-size solutes) and sieving mechanism (for larger solutes). The sieving mechanism governs the filtration behavior in the nonwoven/polyvinylidene fluoride-polyacrylic acid/graphene oxide composite membrane.
Induced Topological Superconductivity in a BiSbTeSe2-Based Josephson Junction
Authors: de Ronde Bob , Li Chuan , Huang Yingkai , Brinkman Alexander
Published: April 2020

A 4 π -periodic supercurrent through a Josephson junction can be a consequence of the presence of Majorana bound states. A systematic study of the radio frequency response for several temperatures and frequencies yields a concrete protocol for examining the 4 π -periodic contribution to the supercurrent. This work also reports the observation of a 4 π -periodic contribution to the supercurrent in BiSbTeSe 2 -based Josephson junctions. As a response to irradiation by radio frequency waves, the junctions showed an absence of the first Shapiro step. At high irradiation power, a qualitative correspondence to a model including a 4 π -periodic component to the supercurrent is found.
Targeted Breast Milk Fortification for Very Low Birth Weight (VLBW) Infants: Nutritional Intake, Growth Outcome and Body Composition
Authors: Parat Sumesh , Raza Praneeta , Kamleh May , Super Dennis , Groh-Wargo Sharon
Published: April 2020

Despite improvements in nutritional management, preterm infants continue to face high rates of postnatal growth restriction. Because variability in breast milk composition may result in protein and energy deficits, targeted fortification has been advocated. We conducted an interventional study to compare body composition and growth outcomes of very low birth weight infants fed targeted protein-fortified human milk (HM) with those fed standard fortified HM. If mother’s own milk was not available, donor milk was used. Weekly analysis of HM with mid-infrared spectroscopy was conducted and additional protein was added to the fortified HM to ensure a protein intake of 4 g/kg/day. Weekly anthropometric measurements were done. Prior to discharge or at 37 weeks, corrected age skinfold thickness (SFT) measurements as well as body composition measurement using air displacement plethysmography were done. Among 36 preterm infants enrolled, those in the targeted group (n = 17) received more protein and had a larger flank SFT at study end than those in the standard group (n = 19). A pilot post-hoc analysis of subjects having at least 30 intervention days showed a 3% higher fat-free mass in the targeted group. Use of a targeted fortification strategy resulted in a higher protein intake and fat-free mass among those receiving longer intervention.