bluuebunny/crossref_metadata_2025_split huggingface dataset:
Speichel als Matrix für das Humanbiomonitoring in der Arbeits‐ und Umweltmedizin [Biomonitoring Methods in German Language, 2015]
Authors: Michalke B. , Rossbach B. , Göen T. , Schäferhenrich A. , Scherer G. , Hartwig A. ,   MAK Commission
Published: October 2016

Saliva as a matrix for human biomonitoring in occupational and environmental medicinePurpose: Human biomonitoring (HBM) implies the assessment of internal exposure to hazardous substances by measuring the substances, their metabolites or reaction products, as well as effect parameters in human body fluids. Along with blood, plasma and urine, saliva is of increasing interest as an alternative matrix for HBM.Methods: This paper reviews studies that measure salivary background levels of hazardous substances, elevated levels after environmental or occupational exposure, as well as references which deal with physiological and toxicokinetic behaviour of saliva and salivary parameters, respectively.Results: The studies revealed that the determination of biomarkers in saliva is a promising approach for HBM, even if only few substances showed a satisfying correlation with exposure data or established biomonitoring matrices such as blood, plasma and urine. Saliva has been proven to be particularly suitable for substances of low molecular weight such as organic solvents, selected pesticides, cotinine, and for some specific trace elements. Besides several advantages, serious problems and limitations were identified. Above all, the complex interactions between substance properties, sampling procedure, sample preparation, measurement techniques or individual factors, and the salivary analyte level are discussed.Conclusions: A major conclusion of the review is that more scientific studies are needed in order to systematically collect data on parameters, influencing salivary analyte levels. Crucially required is a harmonisation of the sampling as well as the sample preparation techniques and procedures, which is indispensable to achieve an overall comparability and interpretability of salivary biomarker levels.
Chlorinated biphenyls [MAK Value Documentation, 2016]
Authors: Hartwig A. ,   MAK Commission
Published: October 2016

The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has re‐evaluated the maximum concentration at the workplace (MAK value) of chlorinated biphenyls (PCB), considering all toxicological endpoints. Available publications are described in detail.The Commission re‐evaluated the previous distinction of PCB in two groups: congeners with up to 3 and 4 or more chlorine atoms. Recent inhalation studies show that the lung is not expected to be the primary target organ of PCB 3 and PCB 11 but the liver. In feeding studies, Aroclor mixtures containing congeners with up to 3 chlorine atoms yield only liver adenomas but no carcinomas in rats, although some of these congeners are genotoxic. On the other hand, Aroclor mixtures with high amounts of congeners with 4 and more chlorine atoms lead to a high incidence of liver carcinomas in rats. Therefore, for congeners with up to 3 chlorine atoms, the genotoxicity is not decisive for the development of liver tumours but mainly the tumour promotion, which has also been shown for congeners with 4 and more chlorine atoms. The distinction between these two groups is therefore no longer retained and all PCBs are classified in Carcinogen Category 4. As a 4‐week inhalation study in rats with a PCB containing mainly congeners with up to 3 chlorine atoms does not give rise to toxicity at a concentration which is 35 times higher than the previous MAK value for congeners with 4 and more chlorine atoms, this MAK value of 0.003 mg/m3is now set for all PCBs. The assignment to Peak Limitation Category II with an excursion factor of 8 is retained due to the critical systemic effects and to the long half‐life of all PCB. The assignment to Pregnancy Risk Group B is retained, as all PCB damage to the embryo or foetus cannot be ruled out even when the MAK value is observed. The genotoxic potency in vivo is regarded as very low if the MAK value is observed, and all PCB are grouped into Germ Cell Mutagen Category 5.
Ornamental Plants in the United States: An Econometric Analysis of a Household‐Level Demand System
Authors: Hovhannisyan Vardges , Khachatryan Hayk 
Published: October 2016

ABSTRACTThis study provides an empirical analysis of demand for a large group of ornamental plants using a theory‐based demand model. Specifically, consumer preferences are represented by the Almost Ideal Demand System where allowance is made for demand censoring. Given that revealed‐preference data are usually limited to certain ornamental plants and geographical locations, we exploit unique hypothetical purchase data collected via an online survey regarding 16 annual, perennial, and foliage plants from across the United States. The effect of various socio‐economic and demographic factors on demand for plants is quantified. Our findings indicate that ornamental plants are predominantly price‐elastic with foliage plants being more price‐responsive vis‐a‐vis other plant categories. Further, a majority of plants are expenditure‐elastic with the estimates of foliage plants manifesting the greatest variability. Finally, plants in the same category appear to be closer substitutes. Results benefit ornamental plant industry stakeholders as they determine the best pricing strategies in their specific markets.
Synthetic Routes to Thiol‐Functionalized Organic Semiconductors for Molecular and Organic Electronics
Authors: Operamolla Alessandra , Punzi Angela , Farinola Gianluca M. 
Published: October 2016

AbstractOver the few last decades, the potential of using thiol functionalities to induce the self‐assembly of various kinds of molecules on metal surfaces has been widely demonstrated. In particular, π‐conjugated molecules can undergo self‐assembly on metallic surfaces to create electroactive supramolecular layers, which have found important applications in organic and molecular electronics. For this reason, the synthesis of thiol‐functionalized conjugated molecules has been the object of extensive research and many routes have been developed for their synthesis. This Focus Review provides an overview of the state‐of‐the‐art methods for the syntheses of organic semiconductors that are decorated with pendant thiol groups for applications in self‐assembly and molecular and organic electronics. Particular attention is given to synthetic strategies based on organometallic cross‐coupling reactions for the preparation of compounds with extended conjugation.
Total Synthesis of Camptothecin and Related Natural Products by a Flexible Strategy
Authors: Li Ke , Ou Jinjie , Gao Shuanhu 
Published: October 2016

AbstractA flexible strategy for constructing natural products containing indolizinone or quinolizinone scaffolds and their analogues was developed, which was based on a cascade exo hydroamination followed by spontaneous lactamization. This method was applied in the total synthesis of camptothecin in nine steps in a new ring‐forming approach. It was also used to efficiently prepare five biogenetically or structurally related natural alkaloids, including 22‐hydroxyacuminatine, oxypalmatine, norketoyobyrine, naucleficine, and nauclefine, as well as 35 natural‐product‐like molecules. We believe that this method and the small‐molecule library prepared with it can open new avenues for studying the bioactivity of camptothecin and Nauclea natural products.
Mild and Selective Cobalt‐Catalyzed Chemodivergent Transfer Hydrogenation of Nitriles
Authors: Shao Zhihui , Fu Shaomin , Wei Mufeng , Zhou Shaolin , Liu Qiang 
Published: October 2016

AbstractHerein, we describe a selective cobalt‐catalyzed chemodivergent transfer hydrogenation of nitriles to synthesize primary, secondary, and tertiary amines. The solvent effect plays a key role for the selectivity control. The general applicability of this procedure was highlighted by the synthesis of more than 70 amine products bearing various functional groups in high chemoselectivity. Moreover, this mild system achieved >2000 TONs (turnover numbers) for the transfer hydrogenation of nitriles.
Regio‐ and Stereoselective Homologation of 1,2‐Bis(Boronic Esters): Stereocontrolled Synthesis of 1,3‐Diols and Sch 725674
Authors: Fawcett Alexander , Nitsch Dominik , Ali Muhammad , Bateman Joseph M. , Myers Eddie L. , Aggarwal Varinder K. 
Published: October 2016

Abstract1,2‐Bis(boronic esters), derived from the enantioselective diboration of terminal alkenes, can be selectively homologated at the primary boronic ester by using enantioenriched primary/secondary lithiated carbamates or benzoates to give 1,3‐bis(boronic esters), which can be subsequently oxidized to the corresponding secondary‐secondary and secondary‐tertiary 1,3‐diols with full stereocontrol. The transformation was applied to a concise total synthesis of the 14‐membered macrolactone, Sch 725674. The nine‐step synthetic route also features a novel desymmetrizing enantioselective diboration of a divinyl carbinol derivative and high‐yielding late‐stage cross‐metathesis and Yamaguchi macrolactonization reactions.
[Cu13{S2CNnBu2}6(acetylide)4]+: A Two‐Electron Superatom
Authors: Chakrahari Kiran Kumarvarma , Liao Jian‐Hong , Kahlal Samia , Liu Yu‐Chiao , Chiang Ming‐Hsi , Saillard Jean‐Yves , Liu C. W. 
Published: October 2016

AbstractThe first structurally characterized copper cluster with a Cu13 centered cuboctahedral arrangement, a model of the bulk copper fcc structure, was observed in [Cu13(S2CNnBu2)6(C≡CR)4](PF6) (R=C(O)OMe, C6H4F) nanoclusters. Four of the eight triangular faces of the cuboctahedron are capped by acetylide groups in μ3 fashion, and each of the six square faces is bridged by a dithiolate ligand in μ2,μ2 fashion, which leads to a truncated tetrahedron of twelve sulfur atoms. DFT calculations are fully consistent with the description of these Cu13 clusters as two‐electron superatoms, that is, a [Cu13]11+ core passivated by ten monoanionic ligands, with an a1 HOMO containing two 1S jellium electrons.
(C6F5)3B Catalyzed Chemoselective and ortho‐Selective Substitution of Phenols with α‐Aryl α‐Diazoesters
Authors: Yu Zhunzhun , Li Yongfeng , Shi Jiameng , Ma Ben , Liu Lu , Zhang Junliang 
Published: October 2016

AbstractThe development of an efficient method for the site‐selective substitution of unprotected phenols has long been considered as an attractive but challenging task. Herein, we describe a highly chemo‐ and ortho‐selective substitution reaction of phenols with α‐aryl α‐diazoacetates with commercially available (C6F5)3B as the catalyst. This reaction proceeds under simple and mild conditions with high efficiency, it features a wide substrate scope and can be easily scaled up.
Substrate‐Modulated Reductive Graphene Functionalization
Authors: Schäfer Ricarda A. , Weber Konstantin , Koleśnik‐Gray Maria , Hauke Frank , Krstić Vojislav , Meyer Bernd , Hirsch Andreas 
Published: October 2016

AbstractCovalently functionalizing mechanical exfoliated mono‐ and bilayer graphenides with λ‐iodanes led to the discovery that the monolayers supported on a SiO2 substrate are considerably more reactive than bilayers as demonstrated by statistical Raman spectroscopy/microscopy. Supported by DFT calculations we show that ditopic addend binding leads to much more stable products than the corresponding monotopic reactions as a result of the much lower lattice strain of the reactions products. The chemical nature of the substrate (graphene versus SiO2) plays a crucial role.
Long chain branched poly(butylene succinate‐co‐terephthalate) copolyesters using pentaerythritol as branching agent: Synthesis, thermo‐mechanical, and rheological properties
Authors: Lu Jing , Wu Linbo , Li Bo‐Geng 
Published: October 2016

ABSTRACTIncorporating long chain branching (LCB) structure into biodegradable copolyesters can effectively improve their melt strength and film blowing processability. However, branching also results in deterioration of crystallizability which is also important for copolyester properties and processing. In this study, pentaerythritol (PER) was used as branching agent (BA) instead of previous used in‐situ BA, diglycidyl 1,2,3,6‐tetrahydrophthalate (DGT), to synthesize LCB poly(butylene succinate‐co‐terephthalate) (PBST) copolyesters. The chain structure was characterized and the effects of branching on thermal transition, mechanical, and rheological properties were investigated. Similar to DGT, copolymerizing small amount of PER (0.1–0.4 mol %) generates LCB structure and, therefore, improves the melt elasticity or strength and tensile modulus but reduces the elongation at break. Differing from DGT, PER showed higher branching efficiency, and PER‐branched PBSTs exhibited unchanged or even improved crystallization ability compared with linear PBST. The improved melt strength coupled with good crystallizability will endow PER‐branched PBSTs with better film blowing processability. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2017,134, 44544.
Molecular imprinting of dibenzothiophene using vinyl pyridine monomers: Fabrication and performance
Authors: Chen Li , Sun Hui , Zhong Yonghui , Zhang Kaiyu , Zheng Tiantian , Lin Ligang , Cheng Bowen 
Published: October 2016

ABSTRACTMolecular imprinting process was proposed for the sulfur removal from fuels. The novel network‐structured molecularly imprinted polymers (MIPs) were fabricated by arranging 4‐vinyl pyridine functional monomers around dibenzothiophene template compounds, and fixing them with ethylene glycol dimethacrylate as crosslinking agent. The effects of dispersed phase, washing after treatment, content of template molecule, and crosslinking agent on the recognition ability of MIPs have been investigated. The practical performance is obtained by the FT‐IR, morphology, and thermal analysis as well as the recognition ability for dibenzothiophene under various feed sulfur concentrations and recognition time. The recognition ability of MIPs under 1000 mg/L feed sulfur concentration was 4.53 mg S/g. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44552.
Pebax–polydopamine microsphere mixed‐matrix membranes for efficient CO2 separation
Authors: Liu Yuanyuan , Li Xueqin , Qin Yun , Guo Ruili , Zhang Jianshu 
Published: October 2016

ABSTRACTNovel facilitated‐transport mixed‐matrix membrane (MMM) were prepared through the incorporation of polydopamine (PDA) microspheres into a poly(amide‐b‐ethylene oxide) (Pebax MH 1657) matrix to separate CO2–CH4 gas mixtures. The Pebax–PDA microsphere MMMs were characterized by Fourier transform infrared spectroscopy, scanning electron microcopy, X‐ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. The PDA microspheres acted as an adhesive filler and generated strong interfacial interactions with the polymer matrix; this generated a polymer chain rigidification region near the polymer–filler interface. Polymer chain rigidification usually results in a larger resistance to the transport of gas with a larger molecular diameter and a higher CO2–CH4 selectivity. In addition, the surface of PDA microspheres contained larger numbers of amine, imine, and catechol groups; these were beneficial to the improvement of the CO2 separation performance. Compared with the pristine Pebax membrane, the MMM with a 5 wt % PDA microsphere loading displayed a higher gas permeability and selectivity; their CO2 permeability and CO2–CH4 selectivity were increased by 61 and 60%, respectively, and surpassed the 2008 Robeson upper bound line. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44564.
Synthesis of CNT‐polyurethane nanocomposites using ester‐based polyols with different molecular structure: Mechanical, thermal, and electrical properties
Authors: Shamsi Ramin , Mahyari Mojtaba , Koosha Mojtaba 
Published: October 2016

ABSTRACTPolyurethanes (PUs) were prepared by in situ polymerization of three diisocyanate with three synthesized low cost ester‐based polyols. The effect of diisocyanate type, diol structure, and molar ratio of diisocyanate to polyol on the mechanical properties was examined and the optimum chemical structure was introduced regarding the superior mechanical properties. Also, in presence of well dispersed hydroxylated multiwalled carbon nanotubes (CNT), PU/CNT nanocomposites were synthesized and fully characterized. The results showed that PU synthesized based on 1,4‐butane diol (BDO) has the best mechanical properties and thermal stability. Also, the PU samples synthesized from 1,6‐hexamethylene diisocyanate (HDI) were more profitable than aromatic diisocyanate structures due to higher crystallinity and microstructure packing. The nanocomposite sample containing 1.5% CNT was the optimum composition for the maximum tensile strength and electrical conductivity. This result was related to the uniform dispersion and bonding of CNTs to PU chains at this composition, while aggregates were formed at higher concentration of CNTs which increased the defects and reduced the uniformity of the structure. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44567.
Upgrading Electroresistive Memory from Binary to Ternary Through Single‐Atom Substitution in the Molecular Design
Authors: Cheng Xue‐Feng , Shi Er‐Bo , Hou Xiang , Xia Shu‐Gang , He Jing‐Hui , Xu Qing‐Feng , Li Hua , Li Na‐Jun , Chen Dong‐Yun , Lu Jian‐Mei 
Published: October 2016

AbstractHerein, two molecules based on urea and thiourea, which differ by only a single atom, were designed, successfully synthesized, and fabricated into resistive random‐access memory devices (RRAM). The urea‐based molecule showed binary write‐once‐read‐many (WORM) storage behavior, whereas the thiourea‐based molecule demonstrated ternary storage behavior. Atomic‐force microscopy (AFM) and X‐ray diffraction (XRD) patterns show that both molecules have smooth morphology and ordered layer‐by‐layer lamellar packing, which is beneficial for charge transportation and, consequently, device performance. Additionally, the optical and electrochemical properties indicate that the thiourea‐based molecule has a lower bandgap and may be polarized by trapped charges, thus the formation of a continuous conductive channel and electric switching occurs at lower bias voltage, which results in ternary WORM behavior. This study, together with our previous work on single‐atom substitution, may be useful to tune and improve device performance in the future design of organic memory.
Design of nanoscale enzyme complexes based on various scaffolding materials for biomass conversion and immobilization
Authors: Hyeon Jeong Eun , Shin Sang Kyu , Han Sung Ok 
Published: October 2016

AbstractThe utilization of scaffolds for enzyme immobilization involves advanced bionanotechnology applications in biorefinery fields, which can be achieved by optimizing the function of various enzymes. This review presents various current scaffolding techniques based on proteins, microbes and nanomaterials for enzyme immobilization, as well as the impact of these techniques on the biorefinery of lignocellulosic materials. Among them, architectural scaffolds have applied to useful strategies for protein engineering to improve the performance of immobilized enzymes in several industrial and research fields. In complexed enzyme systems that have critical roles in carbon metabolism, scaffolding proteins assemble different proteins in relatively durable configurations and facilitate collaborative protein interactions and functions. Additionally, a microbial strain, combined with designer enzyme complexes, can be applied to the immobilizing scaffold because the in vivo immobilizing technique has several benefits in enzymatic reaction systems related to both synthetic biology and metabolic engineering. Furthermore, with the advent of nanotechnology, nanomaterials possessing ideal physicochemical characteristics, such as mass transfer resistance, specific surface area and efficient enzyme loading, can be applied as novel and interesting scaffolds for enzyme immobilization. Intelligent application of various scaffolds to couple with nanoscale engineering tools and metabolic engineering technology may offer particular benefits in research.
Theoretical Calculations on the Feasibility of Microalgal Biofuels: Utilization of Marine Resources Could Help Realizing the Potential of Microalgae
Authors: Park Hanwool , Lee Choul‐Gyun 
Published: October 2016

AbstractMicroalgae have long been considered as one of most promising feedstocks with better characteristics for biofuels production over conventional energy crops. There have been a wide range of estimations on the feasibility of microalgal biofuels based on various productivity assumptions and data from different scales. The theoretical maximum algal biofuel productivity, however, can be calculated by the amount of solar irradiance and photosynthetic efficiency (PE), assuming other conditions are within the optimal range. Using the actual surface solar irradiance data around the world and PE of algal culture systems, maximum algal biomass and biofuel productivities were calculated, and feasibility of algal biofuel were assessed with the estimation. The results revealed that biofuel production would not easily meet the economic break‐even point and may not be sustainable at a large‐scale with the current algal biotechnology. Substantial reductions in the production cost, improvements in lipid productivity, recycling of resources, and utilization of non‐conventional resources will be necessary for feasible mass production of algal biofuel. Among the emerging technologies, cultivation of microalgae in the ocean shows great potentials to meet the resource requirements and economic feasibility in algal biofuel production by utilizing various marine resources.
Protease substrate profiling using bacterial display of self‐blocking affinity proteins and flow‐cytometric sorting
Authors: Sandersjöö Lisa , Jonsson Andreas , Löfblom John 
Published: October 2016

AbstractProteases are involved in fundamental biological processes and are important tools in both biotechnological and biomedical research. An important property of proteases is to discriminate among potential substrates. Here, a new method for substrate profiling of proteases is presented. The substrates are displayed between two anti‐idiotypic affinity domains on the Gram‐positive bacterium Staphylococcus carnosus. The first domain functions as a reporter tag and has affinity for a labeled reporter protein, whereas the second domain blocks the reporter tag from interacting with the reporter protein. Site‐specific proteolysis of the substrate results in release of the blocking domain, enabling the reporter tag to bind the labeled reporter protein. Proteolysis is therefore reflected in reporter binding, which is quantified by flow cytometry. First, the method with tobacco etch virus protease (TEVp) is evaluated and then the substrate preference of matrix metalloprotease‐1 (MMP‐1) is determined using two libraries of around three million substrates each. Identified substrate peptides contained the previously reported motif (PXXXHy) and on‐cell determination of apparent kcat/KM revealed that the enriched substrate peptides are hydrolyzed six to eight‐fold more efficiently than a previously reported substrate peptide. The method thus works as intended and the authors believe it has potential as an efficient tool for substrate profiling.