bluuebunny/crossref_metadata_2025 huggingface dataset:
The Stabilization of Glycosyl Cations Through Cooperative Noncovalent Interactions: A Theoretical Perspective
Authors: Franconetti Antonio , Jiménez‐Barbero Jesús , Cabrera‐Escribano Francisca
Published: November 2017

A systematic study of the stabilization of glycosyl cations on aromatic rings is reported at the B3LYP, M06‐2X and M11 levels of theory. In particular, π‐acidic arenes such as fluorobenzenes or naphthalenediimides efficiently stabilize these cations acting cooperatively as sandwich‐type ternary cation–π–anion systems. The stabilization and cooperativity in polar (both protic and aprotic) and non‐polar solvents has been also evaluated by using the polarizable continuum model. In addition, the role of the protecting group at the C‐2 position (methyl, acetyl, benzyl, and pivaloyl) for this noncovalent stabilization has been explored, as well as the behaviour of the corresponding 2‐deoxy glycosyl cation.
Electrochemistry of Metalloproteins Attached through Functional Self‐Assembled Monolayers on Gold and Ferromagnetic Electrodes
Authors: Mondal Prakash Chandra , Fontanesi Claudio
Published: November 2017

We report the experimental results of a study of the electron‐transfer processes of redox‐active metalloproteins bound to mixed self‐assembled monolayers (SAMs) on magnetic (nickel or ultrathin gold‐coated nickel) or nonmagnetic (gold) electrodes. Metalloproteins, such as hemoglobin (Hb), Cytochrome C (Cyt C), and Cyt C oxidase, are attached through electrostatic interactions to the free carboxylate or imidazole groups present in the mixed SAMs. The formation of both mixed SAMs and SAM/metalloprotein heterostructures were confirmed by using advanced surface analysis techniques, such as polarization modulation infrared reflection absorption spectroscopy and aqueous contact angle measurements. Electrochemical measurements indicated a stronger electronic coupling between Hb and Cyt C oxidase and the mixed‐SAM‐coated gold or gold‐coated‐nickel electrodes, whereas a weaker coupling was found between the protein and the pure nickel electrode. Surface coverage and the electron‐transfer rate constant were estimated from the cyclic voltammetry data.
Image analysis of neural stem cell division patterns in the zebrafish brain
Authors: Lupperger Valerio , Buggenthin Felix , Chapouton Prisca , Marr Carsten
Published: November 2017

Proliferating stem cells in the adult body are the source of constant regeneration. In the brain, neural stem cells (NSCs) divide to maintain the stem cell population and generate neural progenitor cells that eventually replenish mature neurons and glial cells. How much spatial coordination of NSC division and differentiation is present in a functional brain is an open question. To quantify the patterns of stem cell divisions, one has to (i) identify the pool of NSCs that have the ability to divide, (ii) determine NSCs that divide within a given time window, and (iii) analyze the degree of spatial coordination. Here, we present a bioimage informatics pipeline that automatically identifies GFP expressing NSCs in three‐dimensional image stacks of zebrafish brain from whole‐mount preparations. We exploit the fact that NSCs in the zebrafish hemispheres are located on a two‐dimensional surface and identify between 1,500 and 2,500 NSCs in six brain hemispheres. We then determine the position of dividing NSCs in the hemisphere by EdU incorporation into cells undergoing S‐phase and calculate all pairwise NSC distances with three alternative metrics. Finally, we fit a probabilistic model to the observed spatial patterns that accounts for the non‐homogeneous distribution of NSCs. We find a weak positive coordination between dividing NSCs irrespective of the metric and conclude that neither strong inhibitory nor strong attractive signals drive NSC divisions in the adult zebrafish brain. © 2017 The Authors. Cytometry Part A published by Wiley Periodicals, Inc. on behalf of ISAC.
Artificial noise–aided secure communication in a bidirectional relaying network
Authors: Li An , Xu Yizhu , Wang Yuhao , Sun Lihua
Published: November 2017

An artificial noise strategy is proposed for amplify‐and‐forward bi‐directional relay network where the eavesdropper can wiretap the relay channels in both hops. Artificial noise is used to confuse the eavesdropper and improve its secrecy. Specifically, the source and the relay are allowed to split their available transmit power into 2 parts: a useful information portion and a jamming portion to transmit a jamming signal. The mathematical model is established for 2‐way relay network with an eavesdropper. The secrecy rate achieved by using artificial jamming is derived from the above model. The optimal power allocation with individual power constraint is obtained via sequential quadratic programming to maximize the secrecy sum rate, and 2 special cases are investigated. Furthermore, the benchmark is provided for the purpose of performance comparison. Simulation results show that the proposed strategy can significantly improve the secrecy sum rate by using artificial noise to jam the eavesdropper.
Detailed characterization of human Mycobacterium tuberculosis specific HLA‐E restricted CD8+ T cells
Authors: Prezzemolo Teresa , van Meijgaarden Krista E. , Franken Kees L.M.C. , Caccamo Nadia , Dieli Francesco , Ottenhoff Tom H.M. , Joosten Simone A.
Published: November 2017

HLA‐E presented antigens are interesting targets for vaccination given HLA‐Es’ essentially monomorphic nature. We have shown previously that Mycobacterium tuberculosis (Mtb) peptides are presented by HLA‐E to CD8+ effector T cells, but the precise phenotype and functional capacity of these cells remains poorly characterized. We have developed and utilized in this study a new protocol combining HLA‐E tetramer with intracellular staining for cytokines, transcription factors and cytotoxic molecules to characterize these cells in depth. We confirm in this study the significantly increased ex vivo frequency of Mtb‐peptide/HLA‐E‐TM+ CD8+ T cells in the circulation of patients with active tuberculosis (TB). HLA‐E restricted CD8+ T cells from TB patients produced more IL‐13 than cells from controls or subjects with latent tuberculosis infection (LTBI). Compared to total CD8+ T cells, HLA‐E restricted cells produced more IFNγ, IL‐4, IL‐10, and granulysin but less granzyme‐A. Moreover, compared to “classical” Mtb specific HLA‐A2 restricted CD8+ T cells, HLA‐E restricted CD8+ T cells produced less TNFα and perforin, but more IL‐4. In conclusion, HLA‐E restricted‐ Mtb specific cells can produce Th2 cytokines directly.
Study of the Electronic Structure of NiGa2S4 and Extraction of the Spin Hamiltonian Parameters from Ab Initio Calculations
Authors: Pradines Barthélémy , Lacombe Lionel , Guihéry Nathalie , Suaud Nicolas
Published: November 2017

The magnitude of the parameters of the various proposed model Hamiltonians used to model the macroscopic properties of NiGa2S4 and to interpret experimental observations has been the subject of controversy for more than a decade. Both the nature of the relevant operators (magnetic couplings, biquadratic exchange, and anisotropic terms) and the values of their corresponding interactions are far from settled. Through effective Hamiltonian theory and correlated relativistic ab initio calculations, theoretical chemistry can rigorously extract all the required operators and the magnitudes of their corresponding interactions. In this article, we report the values of all relevant interactions. Contrarily to what is often reported, it is shown that: (1) the biquadratic exchange is negligible and smaller than the three‐body terms, (2) the nearest‐neighbor interaction is ferromagnetic and dominant, (3) the next‐nearest‐neighbor coupling is ferromagnetic and small, (4) the next‐next‐nearest‐neighbor coupling is antiferromagnetic and three times smaller than the nearest‐neighbor interaction, and (5) the axial parameter for the local magnetic anisotropy is of the same order of magnitude as the nearest‐neighbor magnetic coupling.
A mechanically strengthened polyacrylamide gel matrix fully compatible with electrophoresis of proteins and nucleic acids
Authors: Pushparajan Charlotte , Goswami Shailesh K. , McAdam C. John , Hanton Lyall R. , Dearden Peter K. , Moratti Stephen C. , Cridge Andrew G.
Published: November 2017

Polyacrylamide gel electrophoresis is a universal tool in a biochemist's toolkit for protein and nucleic acid separation and subsequent visualisation and analysis. The standard formulation of polyacrylamide gels consists of acrylamide (ACM) monomer crosslinked with bisacrylamide (MBA) which creates a gel with excellent sieving properties but which is mechanically fragile and prone to tearing during post‐electrophoresis manipulations involved in visualisation and analysis. By adding a poly(ethylene oxide) macro‐crosslinker to the standard gel formulation, we have created a tough gel matrix that can be used to fractionate proteins and nucleic acids by polyacrylamide gel electrophoresis. The protein and nucleic acid resolving capabilities and performance during staining and electroblotting of the tough gel matrix rivals that of conventional acrylamide/bisacrylamide gels. The tough gel matrix is resistant to tear and remarkably elastic, capable of stretching to over four times its original length before breaking, and represents a significant improvement over standard polyacrylamide gel formulations.
Insight into Optimization, isotherm, kinetics, and thermodynamics of fluoride adsorption onto activated alumina
Authors: Dhawane Sumit H. , Khan Anoar Ali , Singh Kiran , Tripathi Ajay , Hasda Rahala , Halder Gopinath
Published: November 2017

Investigation of essential technique to diminish the exceeded limit of fluoride in groundwater is the need of the hour due to severe adverse effects of fluoride on human health. The present study highlights the prospective of activated alumina, a defluoridating agent for the elimination of excess fluoride (F−) concentration from aqueous solution by using batch adsorption techniques. The adsorptive removal of fluoride was optimized by means of response surface methodology (RSM) considering the parameters in the range of pH (6‐8), contact time (60‐120 min), alumina dose (1‐2 g), agitation speed (200‐300 RPM), and temperature (25‐45°C). The sorbent was instrumentally characterized to study the surface morphology and chemical composition by SEM (Scanning Electron Microscopy), EDX (X‐ray Energy dispersive analysis) and XRD (X‐ray Diffractometry). The optimized condition for the defluoridation procedure was obtained as pH 6, contact time 120 min, alumina dose 2 g, temperature 45°C, and agitation speed of 200 RPM gives 86.1% of fluoride removal. The equilibrium adsorption performances were studied and the data were fitted with both the Freundlich and Langmuir isotherms and showed Freundlich model was fitted well which signifies multilayer adsorption. The defluoridation method followed pseudo‐second‐order kinetics. Gibbs free energy showed that the process is feasible at all three operating temperatures. The statistical parameters proved the significance and applicability of the model for optimization of the defluoridation process using activated alumina as an adsorbent. Hence, alumina could be an eminent adsorbent for the defluoridation of wastewater. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 766–776, 2018
Evaluation of MESSAGE communication strategy combined with group reminiscence therapy on elders with mild cognitive impairment in long‐term care facilities
Authors: Zhang Huan‐huan , Liu Peng‐cheng , Ying Jie , Shi Ying , Wang Shou‐qi , Zhang Mei‐ling , Sun Jiao
Published: November 2017

Objective

This study aims to evaluate combined effects of MESSAGE communication strategy and group reminiscence therapy (GRT) on elders with mild cognitive impairment (MCI) in long‐term care facilities in Changchun, China.

Methods

This study is a nonrandomized controlled trial. Subjects included 60 elders with MCI. Participants were divided into intervention (MESSAGE communication strategy combined with GRT) and control groups (without any intervention). Primary outcomes comprised cognitive function and quality of life of elderly people, as measured by the Beijing version of the Montreal Cognitive Assessment and the Chinese (mainland) version of Short‐Form 36 Health Survey assessment.

Results

We observed significant changes in cognitive function with mean difference of 1.962 after 12 weeks (P = .000; 95% confidence interval [CI] = 1.341, 2.582), delayed memory dimension of 1.115 (P = .003; 95% CI = 0.417, 1.813). The intervention group exhibited the following improvements: general health of 14.731 (P = .000; 95% CI = 8.511, 20.951), mental health of 21.038 (P = .000; 95% CI = 17.301, 24.776), role‐emotional of 26.925 (P = .003; 95% CI = 10.317, 45.533), and vitality of 14.231 (P = .000; 95% CI = 10.084, 18.377).

Conclusions

Using a sample of Chinese elderly people with MCI and residing in long‐term care facilities, we concluded that application of MESSAGE communication strategy combined with GRT resulted in improved cognitive function and quality of life.
4‐(4,6‐Dimethoxy‐1,3,5‐triazin‐2‐yl)‐4‐methylmorpholinium Toluene‐4‐sulfonate (DMT/NMM/TsO−) Universal Coupling Reagent for Synthesis in Solution
Authors: Fraczyk Justyna , Kaminski Zbigniew J. , Katarzynska Joanna , Kolesinska Beata
Published: November 2017

4‐(4,6‐Dimethoxy‐1,3,5‐triazin‐2‐yl)‐4‐methylmorpholinium toluene‐4‐sulfonate (DMT/NMM/TsO−), a representative member of the inexpensive and environmentally‐friendly N‐triazinylammonium family of sulfonates, has been found to be a very effective coupling reagent for the synthesis of amides, esters and peptides in solution. This study confirms the usefulness of DMT/NMM/TsO− for peptide synthesis in solution, starting from Z‐, Fmoc‐, and Boc‐protected substrates as well as unnatural building blocks. Peptide synthesis with DMT/NMM/TsO− produced high yields, with high crude product purity and low risk of racemization. In all cases, stoichiometric amounts of reagents were used and the standard synthetic procedure, without the need for time‐consuming optimization stages or expensive chromatographic purification. DMT/NMM/TsO− was also found to be very useful for the synthesis of oligopeptides using a fragment coupling strategy.
Evaluation of energy balance closure adjustment methods by independent evapotranspiration estimates from lysimeters and hydrological simulations
Authors: Mauder Matthias , Genzel Sandra , Fu Jin , Kiese Ralf , Soltani Mohsen , Steinbrecher Rainer , Zeeman Matthias , Banerjee Tirtha , De Roo Frederik , Kunstmann Harald
Published: November 2017

Non‐closure of the surface energy balance is a frequently observed phenomenon of hydrometeorological field measurements, when using the eddy‐covariance method, which can be ascribed to an underestimation of the turbulent fluxes. Several approaches have been proposed in order to adjust the measured fluxes for this apparent systematic error. However, there are uncertainties about partitioning of the energy balance residual between the sensible and latent heat flux and whether such a correction should be applied on 30‐min data or longer time scales. The data for this study originate from two grassland sites in southern Germany, where measurements from weighable lysimeters are available as reference. The adjusted evapotranspiration rates are also compared with joint energy and water balance simulations using a physically based distributed hydrological model. We evaluate two adjustment methods: the first one preserves the Bowen ratio and the correction factor is determined on a daily basis. The second one attributes a smaller portion of the residual energy to the latent heat flux than to the sensible heat flux for closing the energy balance for every 30‐min flux integration interval. Both methods lead to an improved agreement of the eddy‐covariance based fluxes with the independent lysimeter estimates and the physically based model simulations. The first method results in a better comparability of evapotranspiration rates, and the second method leads to a smaller overall bias. These results are similar between both sites despite considerable differences in terrain complexity and grassland management. Moreover, we found that a daily adjustment factor leads to less scatter than a complete partitioning of the residual for every half‐hour time interval. The vertical temperature gradient in the surface layer and friction velocity were identified as important predictors for a potential future parameterisation of the energy balance residual.
Biodiversity impact assessment (BIA+) – methodological framework for screening biodiversity
Authors: Winter Lisa , Pflugmacher Stephan , Berger Markus , Finkbeiner Matthias
Published: November 2017

For the past 20 years, the life cycle assessment (LCA) community has sought to integrate impacts on biodiversity into the LCA framework. However, existing impact assessment methods still fail to do so comprehensively because they quantify only a few impacts related to specific species and regions. This paper proposes a methodological framework that will allow LCA practitioners to assess currently missing impacts on biodiversity on a global scale. Building on existing models that seek to quantify the impacts of human activities on biodiversity, the herein proposed methodological framework consists of 2 components: a habitat factor for 14 major habitat types and the impact on the biodiversity status in those major habitat types. The habitat factor is calculated by means of indicators that characterize each habitat. The biodiversity status depends on parameters from impact categories. The impact functions, relating these different parameters to a given response in the biodiversity status, rely on expert judgments. To ensure the applicability for LCA practitioners, the components of the framework can be regionalized on a country scale for which LCA inventory data is more readily available. The weighting factors for the 14 major habitat types range from 0.63 to 1.82. By means of area weighting of the major habitat types in a country, country-specific weighting factors are calculated. In order to demonstrate the main part of the framework, examples of impact functions are given for the categories “freshwater eutrophication” and “freshwater ecotoxicity” in 1 major habitat type. The results confirm suitability of the methodological framework. The major advantages are the framework's user-friendliness, given that data can be used from LCA databases directly, and the complete inclusion of all levels of biodiversity (genetic, species, and ecosystem). It is applicable for the whole world and a wide range of impact categories. Integr Environ Assess Manag 2018;14:282–297. © 2017 SETAC

Key Points

Impact assessment methods can help to evaluate human made impacts on biodiversity in order to stop the alarming decrease of life on earth. The proposed methodological framework brings life cycle assessment and biodiversity together in order to assess product environmental impacts on biodiversity. A new approach is developed based on existing ideas. This approach can be applied globally and with regard to different human-made impacts.
Decision Models for the Ranking of Agricultural Water Demand Management Strategies in an Arid Region
Authors: Banihabib Mohammad Ebrahim , Shabestari Mohammad Hadi
Published: November 2017

The agricultural sector is the largest consumer of water and its demand management has a significant impact on water resources of arid areas. This research proposes a hybrid multi‐criteria decision‐making (MCDM) model to prioritize agricultural water demand management (AWDM) strategies based on surveys carried out with 35 Iranian experts in an arid region. It hybridized the advantages of the modified technique for order preference by similarity to ideal solution (MTOPSIS) and the analytical hierarchy process (AHP) methods, and it is called MTAHP. The AHP model is used to determine the relative weights and consistency ratio assessment and finally the MTOPSIS model is used to rank the strategies. Moreover, ELimination and Choice Expressing REality III (ELECTRE III) as a non‐compensatory model and simple additive weighting (SAW) as a compensatory model were used for comparison with the proposed model. The proposed model result was similar to the SAW model but different from ELECTRE III. High‐ranked strategies are training farmers, improvement of cropping patterns and land levelling and modernization of the irrigation systems in the region, respectively. The results of this research show the ability of the hybrid model of AHP and MTOPSIS to prioritize the strategies for AWDM which is recommended for other similar regions. Copyright © 2017 John Wiley & Sons, Ltd.
MiR 376c inhibits osteoblastogenesis by targeting Wnt3 and ARF‐GEF‐1 ‐facilitated augmentation of beta‐catenin transactivation
Authors: Kureel Jyoti , John Aijaz A. , Prakash Ravi , Singh Divya
Published: November 2017

Wnt signaling pathway plays important role in all aspects of skeletal development which include chondrogenesis, osteoblastogenesis, and osteoclastogenesis. Induction of the Wnt‐3 signaling pathway promotes bone formation while inactivation of the pathway leads to bone related disorders like osteoporosis. Wnt signaling thus has become a desired target to treat osteogenic disorders. MicroRNAs (miRNAs) represent an important category of elements that interact with Wnt signaling molecules to regulate osteogenesis. Here, we show that miR‐376c, a well‐characterized tumor suppressor which inhibits cell proliferation and invasion in osteosarcoma by targeting to transforming growth factor‐alpha, suppresses osteoblast proliferation, and differentiation. Over‐expression of miR‐376c inhibited osteoblast differentiation, whereas inhibition of miR‐376c function by antimiR‐376c promoted expression of osteoblast‐specific genes, alkaline phosphatase (ALP) activity, and matrix mineralization. Target prediction analysis tools and experimental validation by luciferase 3′ UTR reporter assay along with qRT‐PCR identified Wnt‐3 and ARF‐GEF‐1 as direct targets of miR‐376c. It was seen that over‐expression of miR‐376c leads to repression of canonical Wnt/β‐catenin signaling. Our overall results suggest that miR‐376c targets Wnt‐3 and ARF‐GEF‐1 suppresses ARF‐6 activation which prevents the release of β‐catenin and its transactivation thereby inhibiting osteoblast differentiation. Although miR‐376c is known to be a tumor repressor; we have identified a second complementary function of miR‐376c where it inhibits Wnt‐3‐mediated osteogenesis and promotes bone loss.
An interacting quantum atom study of model SN2 reactions (X–···CH3X, X = F, Cl, Br, and I)
Authors: Alkorta Ibon , Thacker Joseph C. R. , Popelier Paul L. A.
Published: November 2017

The quantum chemical topology method has been used to analyze the energetic profiles in the X– + CH3X → XCH3 + X–SN2 reactions, with X = F, Cl, Br, and I. The evolution of the electron density properties at the BCPs along the reaction coordinate has been analysed. The interacting quantum atoms (IQA) method has been used to evaluate the intra‐atomic and interatomic energy variations along the reaction path. The different energetic terms have been examined by the relative energy gradient method and the ANANKE program, which enables automatic and unbiased IQA analysis. Four of the six most important IQA energy contributions were needed to reproduce the reaction barrier common to all reactions. The four reactions considered share many common characteristics but when X = F a number of particularities occur. © 2017 Wiley Periodicals, Inc.
Usability of Functional MRI in Clinical Studies for Fast and Reliable Assessment of Renal Perfusion and Quantification of Hemodynamic Effects on the Kidney
Authors: Getzin Tobias , May Marcus , Schmidbauer Martina , Gutberlet Marcel , Martirosian Petros , Oertel Reinhard , Wacker Frank , Schindler Christoph , Hueper Katja
Published: November 2017

The purpose of this study was to evaluate contrast‐media–free arterial spin labeling, a technique of functional magnetic resonance imaging (MRI), for assessment of kidney perfusion in a clinical study. We examined renal perfusion by arterial spin labeling in 15 healthy adults using a clinical 1.5‐T MRI system, twice under baseline conditions and 60 minutes after a single oral dose of 50 mg captopril. Data evaluation included assessment of interstudy and interrater reproducibility in addition to the pharmacological effect of captopril on kidney perfusion and a sample size calculation for potential application of the technique in pharmacological intervention studies. Interstudy reproducibility of cortical and medullary kidney perfusion was excellent (intraclass correlation coefficients 0.77 and 0.83, respectively). Interrater reproducibility was excellent in the cortex and good in the medulla (intraclass correlation coefficients 0.97 and 0.66, respectively). Ingestion of 50 mg captopril was associated with an 11% drop of systolic blood pressure and a rise in kidney perfusion by 22% in the cortex (369 ± 48 vs 452 ± 56 mL/[min·100 g], P < .001) and 26% in the medulla (157 ± 39 to 198 ± 45 ml/[min·100 g]; P < .01). Statistical power analysis revealed that a small sample size of only 6 participants is needed in a clinical trial to capture an equal change in kidney perfusion to the one induced by 50 mg captopril with a statistical power of 82% and an α error of 0.05. In conclusion, funtional MRI with arterial spin labeling is a reliable method for quantification of kidney perfusion and for fast assessment of pharmacologically induced renal perfusion changes, allowing low case numbers.
Improvement of enzyme stability for alkyl esters synthesis in miniemulsion systems by using media engineering
Authors: de Barros Dragana PC , Pinto Fátima , Pfluck Ana CD , Dias Andreia SA , Fernandes Pedro , Fonseca Luís P
Published: November 2017

BACKGROUND

Oil‐in‐water miniemulsions have been suggested to display potential for application as a ‘green’ system for enzymatic alkyl ester synthesis. Still, a realistic assessment of the feasibility of this approach for practical applications requires further insight, namely the relation between enzyme stability and reaction operational conditions. The objective of this work is within such scope. Accordingly, it extends previous research on esterification catalyzed by Fusarium solani pisi cutinase, by addressing medium‐chain length substrates, and aims to contribute to the optimization of reaction conditions and towards the design of an efficient set‐up.

RESULTS

The esterification yield was significantly enhanced (e.g. 50% increase for octyl octanoate system) through the correction of the initial pH of the reaction medium to pH 6. Under such environment, conformational changes of the enzyme were negligible after 24 h, resulting in improved enzyme stability for all systems under study. Maximum esterification rate (3.59 mmol min‐1) and product yield (91%) were achieved for octyl decanoate synthesis. Fed‐batch mode of operation allowed for the production of 1 mol L‐1 hexyl octanoate, while retaining enzyme activity over 5 days. Consecutive batch runs allowed for the cumulative production of 1.1 mol L‐1 hexyl octanoate after four cycles.

CONCLUSIONS

Medium engineering enabled the use of miniemulsion systems for the synthesis of medium‐chain alkyl esters and increase in the final concentration of the intended product. Through a fed‐batch mode the enzyme stability and reutilization were tuned allowing long‐term utilization of the free enzyme which could not be achieved through a repeated batch system. © 2017 Society of Chemical Industry
Continuous cell flocculation for recombinant antibody harvesting
Authors: Burgstaller Daniel , Krepper Walpurga , Haas Josselyn , Maszelin Marine , Mohoric Jure , Pajnic Katja , Jungbauer Alois , Satzer Peter
Published: November 2017

BACKGROUND

Integrated continuous production technology is of great interest in biopharmaceutical industry. Efficient, flexible and cost effective methods for continuous cell removal have to be developed, before a fully continuous and integrated product train can be realized. The paper describes the development and testing of such an integrated continuous and disposable set‐up for cell separation by flocculation combined with depth filtration.

RESULTS

Screening of multiple flocculation agents, depth filters, and conditions demonstrated that the best performance was obtained with 0.0375% polydiallyldimethylammonium chloride (pDADMAC; a polycationic flocculation agent) in combination with Clarisolve® depth filters. Using this set‐up, a 4‐fold decrease of filtration area was achieved relative to standard filtration without flocculation, with yields of ≥97% and DNA depletion of up to 99%. Continuous operation was accomplished using a simple tubular reactor design with parallelization of the filtration. The reactor length was selected to allow a 13.2‐min residence time, which was sufficient to complete flocculation in batch experiments. Continuous flocculation performance was monitored on‐line using focused beam reflectance measurement. Filter switch cycles based on upstream pressure were controlled by in‐line pressure sensors, and were stable from one filter to the next.

CONCLUSION

It was demonstrated that stable and efficient continuous flocculation associated with depth filtration can be easily accomplished using tubular reactors and parallelization. Continuous cell separation is essential for the development of fully continuous integrated process trains. This cost‐efficient disposable design run in continuous mode significantly reduces facility foot print, process costs and enables great flexbility. © 2017 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
Gemini‐type cationic surfactant‐directed synthesis of hollow ZSM‐5 zeolite with intracrystalline mesopores and its application in the hydroxylation of phenol
Authors: Shen Yu , Wang Fumin , Han Zongzhuang , Zhang Xubin
Published: November 2017

BACKGROUND

ZSM‐5 zeolites are of great importance in industrial catalysis. However, the diffusion limitations caused by small pore opening restrict the extent of catalytic conversions over conventional ZSM‐5. Many studies have shown that mass transfer in zeolite channels can be improved by controlling the morphology or creating additional mesoporosity. Here, the catalytic performance is further improved by the creation of hollow structure and intracrystalline mesopores in ZSM‐5 zeolite.

RESULTS

The characterization results demonstrated that hollow ZSM‐5 with intracrystalline mesopores can be synthesized by using a simple one‐step hydrothermal strategy with a commercial gemini‐type cationic surfactant containing hydrophilic hydroxyl groups. Compared with the Fe‐substituted conventional ZSM‐5, the Fe‐substituted hollow ZSM‐5 with intracrystalline mesopores show remarkably enhanced catalytic performance in the hydroxylation of phenol. About 52.2% conversion of phenol can be obtained with almost 96.8% selectivity to dihydroxybenzenes. The catalytic activity remained almost unchanged after five cycles.

CONCLUSION

The newly created hollow structure and intracrystalline mesopores in ZSM‐5 zeolite showed enhanced catalytic activity and reusability for the hydroxylation of phenol, which is higher than most reported systems. The prepared catalyst is a promising alternative material for the hydroxylation of phenol. © 2017 Society of Chemical Industry
Removal of heavy metals by Klebsiella sp. 3S1. Kinetics, equilibrium and interaction mechanisms of Zn(II) biosorption
Authors: Muñoz Antonio Jesús , Espínola Francisco , Ruiz Encarnación
Published: November 2017

BACKGROUND

In this work, the ability of biosorption and bioaccumulation of Zn (II) ions by Klebsiella sp. 3S1 has been investigated. This bacterium had already demonstrated its ability to remove Pb and Ag ions by different mechanisms. The mechanisms involved in the process have been studied using four techniques: FTIR, SEM–EDX, TEM‐EDX and confocal microscopy. Kinetic and equilibrium studies have also been performed.

RESULTS

The main operating variables were optimized by a Rotatable Central Composite Design (RCCD) that yielded the following values: 0.36 g L‐1 biomass, pH 5.20 and 34 °C temperature, although the equilibrium data were obtained at a temperature of 25 °C, more in line with the environmental conditions. The model that best fitted the experimental kinetic data turned out to be the pseudo‐first‐order one. Maximum capacity of biosorption under the Langmuir model was 48.4 mg g‐1. Finally, the presence of two general mechanisms in the biosorption process was confirmed: cytoplasmic bioaccumulation and complex surface adsorption.

CONCLUSIONS

Klebsiella sp. 3S1 can be an effective and inexpensive microorganism to remove heavy metals from contaminated effluents, which along with its ubiquity and great ability to form biofilms, make it a promising biosorbent for use in biofilters. © 2017 Society of Chemical Industry
Factors affecting the separation performance of graphene oxide membranes: mechanical support, properties of graphene oxide, and exotic species
Authors: Mo Yinghui , Zhao Xin , Yuan Tingting , He Benqiao
Published: November 2017

BACKGROUND

Graphene oxide (GO) membrane with 2‐dimensional nanocapillaries has gained worldwide attention. To manipulate the membrane separation performance, most existing studies focused on sandwiching appropriate species between GO layers. This study aimed to provide multiple strategies to manipulate the GO membrane separation performance, including the mechanical support, properties of GO nanosheets, and exotic species (i.e. cross‐linkers and residual water molecules).

RESULTS

Used as the support material, compared with the nitrocellulose membrane, the polyvinylidene fluoride membrane offered stronger mechanical strength to ensure a stable flux. Additional mechanical support could be provided by the non‐woven cloth underneath the GO membrane. The use of GO nanosheets with smaller sizes obtained by centrifugation of the GO suspension increased the water flux and NaCl rejection. Cross‐linking GO layers by Ca2+ resulted in a decreased water flux but increased salt rejection. The same phenomena was observed for the GO membranes post‐treated by vacuum drying, which, compared with air drying, evaporated more residual water molecules from the nanocapillaries.

CONCLUSION

Results suggested that the mechanical support, properties of GO nanosheets, cross‐linkers, and residual water molecules greatly affected the membrane water flux and rejections, which could be utilized as strategies to manipulate the GO membrane separation performance. © 2017 Society of Chemical Industry
Changing world extreme temperature statistics
Authors: Finkel J. M. , Katz J. I.
Published: November 2017

We use the Global Historical Climatology Network – daily database to calculate a nonparametric statistic that describes the rate at which all‐time daily high‐ and low‐temperature records have been set in nine geographic regions (continents or major portions of continents) during periods mostly from the mid‐20th century to the present. This statistic was defined in our earlier work on temperature records in the 48 contiguous United States. In contrast to this earlier work, we find that in every region except North America all‐time high records were set at a rate significantly (at least 3σ) higher than in the null hypothesis of a stationary climate. Except in Antarctica, all‐time low records were set at a rate significantly lower than in the null hypothesis. In Europe, North Africa and North Asia the rate of setting new all‐time highs increased suddenly in the 1990s, suggesting a change in regional climate regime; in most other regions there was a steadier increase.
Resonance Raman studies of Bacillus megaterium cytochrome P450 BM3 and biotechnologically important mutants
Authors: Liu Yilin , McLean Kirsty J. , Munro Andrew W. , Kincaid James R.
Published: November 2017

Cytochrome P450 BM3 is an important model system for mammalian P450s and has great potential for biotechnological applications owing to its high catalytic activity, facilitated by its fused diflavin reductase domain. Mutagenesis studies have shown that Ala‐82 and Phe‐87 are important in controlling molecular selectivity and regioselectivity in BM3 substrate oxidation, with the A82F, F87V, and A82F/F87V double mutant effectively enhancing the affinity for the human P450 drug omeprazole and related proton pump inhibitor drugs. Herein, resonance Raman spectroscopy is used to probe the heme structure and coordination environments of these BM3 mutants, which are known to afford substantial changes in omeprazole recognition. Specifically, it is demonstrated that binding of omeprazole to these BM3 mutants leads to differing degrees of low spin to high spin state conversion of the heme iron. Furthermore, the ferrous‐CO adducts of these proteins are analyzed by resonance Raman to interrogate the effect of substrate binding on the distal pocket architecture, with differing values for the internal modes associated with the Fe‐C‐O fragment reflecting distinct interactions with distal pocket residues.
The nature of plasmon‐exciton codriven surface catalytic reaction
Authors: Liu Wen , Lin Weihua , Zhao Haofei , Wang Peijie , Sun Mengtao
Published: November 2017

In this communication, we propose physical mechanism of plasmon‐exciton codriven surface catalytic reaction, based on the electrochemical graphene mediated surface‐enhanced Raman scattering spectroscopy. It is found that with the help of graphene, the Fermi Level of the graphene‐roughened Ag electrode hybrid system can be significantly increased, which can efficiently promote the efficiency of surface catalytic reaction compared with that driven by roughened Ag electrode alone.
Field findings about milk ethanol stability: a first report of interrelationship between α‐lactalbumin and lactose
Authors: Fagnani Rafael , de Araújo João Paulo Andrade , Botaro Bruno Garcia
Published: November 2017

BACKGROUND

Milk ethanol stability is not only associated with microbiological acidification, but is a phenomenon with many variables that influence the balance of soluble salts, mainly calcium ion activity. On this basis, we wanted to find out more about milk ethanol stability by studying its relationship with milk protein fractions and others major components. The influence of milk composition on ethanol stability was assessed through a predictive model comprising 180 individual raw milk samples. An additional model was used to assess the ethanol stability status as a response to the proteins fractions quantified by electrophoresis.

RESULTS

Of the total samples, 68% were classified as stable and 32% as unstable to alcohol. Milk ethanol instability increased at low values of lactose content and high values of ash percentage. α‐Lactalbumin (α‐La) was also associated with ethanol stability, and the higher the α‐La percentage the lower were the chances of ethanol instability.

CONCLUSION

The lower values of α‐La in unstable milk samples might be related to lower content of lactose, as α‐La promotes lactose synthesis, a key component for the osmotic balance of milk and thus its ethanol stability. This is the first field report linking ethanol stability indirectly with α‐La. © 2017 Society of Chemical Industry
Near‐infrared hyperspectral imaging for detection and quantification of azodicarbonamide in flour
Authors: Wang Xiaobin , Zhao Chunjiang , Huang Wenqian , Wang Qingyan , Liu Chen , Yang Guiyan
Published: November 2017

BACKGROUND

The present study aimed to establish a method for the detection and quantification of azodicarbonamide (ADC) in flour using hyperspectral imaging technology. Hyperspectral images of pure flour, pure ADC and flour–ADC mixtures with different concentrations of ADC were collected. F‐values of one‐way analysis of variance for all possible wavebands within the spectra of the flour and ADC were calculated, and the maximum value indicated that the two wavebands have more significant differences, i.e. the optimal two wavebands. Threshold segmentation was used for band ratio images of two wavebands to create a binary image. This allowed visual identification of ADC‐rich pixels in the mixtures.

RESULTS

The two wavebands with the largest difference between flour and ADC were 2039 nm and 1892 nm. Using the binary image construction method, different concentrations of ADC in flour were identified. The minimum detected concentration was 0.2 g kg−1. In the mixtures, the number of ADC‐rich pixels detected had a good linear relationship with the ADC concentrations, with a correlation coefficient of 0.9845.

CONCLUSION

This study indicated that the band ratio algorithm combination with threshold segmentation for hyperspectral images provides a non‐destructive method for detecting and quantifying of ADC in flour. © 2017 Society of Chemical Industry
Preparation and characterization of a novel molecularly imprinted polymer for the separation of glycyrrhizic acid
Authors: Long Jiapeng , Liang Bing , Li Sanxi , Chen zhenbin
Published: November 2017

Molecularly imprinted polymers of glycyrrhizic acid were prepared by solution polymerization using glycyrrhizic acid as the template molecule, N‐vinypyrrolidone as functional monomer, N,N‐methylene bisacrylamide as cross‐linker and ascorbic acid and hydrogen peroxide as initiators. Focused on the adsorption capacity and separation degree of the polymer to glycyrrhizic acid, the effects of the monomers, crosslinker and initiators were investigated and optimized. Finally, the structure of the polymer was characterized by using Fourier transform infrared spectroscopy and scanning electron microscopy. To obtain objective results, non‐imprinted molecular polymers prepared under the same conditions were also characterized. The adsorption quantity of the polymer was measured by high‐performance liquid chromatography. Under the optimum conditions, the maximum adsorption capacity of glycyrrhizic acid approached 15 mg/g, and the separation degree was as high as 2.5. The adsorption kinetics could be well described by a pseudo‐first‐order model, while the thermodynamics of the adsorption process could be described by the Langmuir model.
Purchase of local food products during trips by international visitors
Authors: Madaleno Ana , Eusébio Celeste , Varum Celeste
Published: November 2017

The contribution made by local products to local economic development has been recognized. While consuming local food products, visitors not only satisfy their vital needs but also interact with local culture and support local development by stimulating demand. Despite this, the determinants of local food product consumption by international visitors have been relatively neglected. The results reveal that the determinants related to interaction with the destination and local products are stronger, but there are differences between visitors' characteristics. The findings contribute to a comprehensive understanding about the interaction of inbound tourism and local food product consumption.
High methylmercury formation in ponds fueled by fresh humic and algal derived organic matter
Authors: Herrero Ortega Sonia , Catalán Núria , Björn Erik , Gröntoft Hannes , Hilmarsson Torfi Geir , Bertilsson Stefan , Wu Pianpian , Bishop Kevin , Levanoni Oded , Bravo Andrea G.
Published: November 2017

Neurotoxic methylmercury causes adverse effects to ecosystem viability and human health. Previous studies have revealed that ponding alters natural organic matter (NOM) composition and increase methylmercury concentrations in rivers, especially in the first years after flooding. Here, we investigate the influence of NOM composition (i.e., sources and degradation status) on mercury methylation rate constants in nine boreal beaver ponds of different ages across Sweden. We show that increased methylmercury concentrations in surface waters is a consequence of enhanced mercury methylation in the pond sediments. Moreover, our results reveal that during the first years after the initial flooding, mercury methylation rates are fueled by the amount of fresh humic substances released from the flooded soils and by an increased production of algal‐derived NOM triggered by enhanced nutrient availability. Our findings indicate that impoundment‐induced changes in NOM composition control mercury methylation processes, causing the raise in MeHg levels in ponds.
Lipid metabolism and functional assessment of discarded human livers with steatosis undergoing 24 hours of normothermic machine perfusion
Authors: Liu Qiang , Nassar Ahmed , Buccini Laura , Iuppa Giuseppe , Soliman Basem , Pezzati Daniele , Hassan Ahmed , Blum Matthew , Baldwin William , Bennett Ana , Chavin Kenneth , Okamoto Toshihiro , Uso Teresa Diago , Fung John , Abu‐Elmagd Kareem , Miller Charles , Quintini Cristiano
Published: November 2017

Normothermic machine perfusion (NMP) is an emerging technology to preserve liver allografts more effectively than cold storage (CS). However, little is known about the effect of NMP on steatosis and the markers indicative of hepatic quality during NMP. To address these points, we perfused 10 discarded human livers with oxygenated NMP for 24 hours after 4‐6 hours of CS. All livers had a variable degree of steatosis at baseline. The perfusate consisted of packed red blood cells and fresh frozen plasma. Perfusate analysis showed an increase in triglyceride levels from the 1st hour (median, 127 mg/dL; interquartile range [IQR], 95‐149 mg/dL) to 24th hour of perfusion (median, 203 mg/dL; IQR, 171‐304 mg/dL; P = 0.004), but tissue steatosis did not decrease. Five livers produced a significant amount of bile (≥5 mL/hour) consistently throughout 24 hours of NMP. Lactate in the perfusate cleared to <3 mmol/L in most livers within 4‐8 hours of NMP, which was independent of bile production rate. This is the first study to characterize the lipid profile and functional assessment of discarded human livers at 24 hours of NMP. Liver Transplantation 24 233–245 2018 AASLD.
Influence of the Hydrophobic–Hydrophilic Nature of Biomedical Polymers and Nanocomposites on In Vitro Biological Development
Authors: Torres Elena , Vallés‐Lluch Anna , Fombuena Vicent , Napiwocki Brett , Lih‐Sheng Turng
Published: November 2017

In this work, cell viability, proliferation, and morphology are studied on two pairs of polymers used in the biomedical field that have similar chemical natures but differ in hydrophobicity. On the one hand, hydrophobic polyester poly(ε‐caprolactone), is modified by blending with poly(lactic acid). On the other hand, the hydrophilic acrylate poly(2‐hydroxyethyl methacrylate) (PHEMA), is copolymerized with ethyl methacrylate (EMA) at a ratio of 50/50 wt.% P(HEMA‐co‐EMA). These two polymers are used as neat resins or combined with hydroxyapatite (HA) nanoparticles and halloysite nanotubes (HNTs) to enhance cell attachment and mechanical properties. Cell proliferation is greater on moderately hydrophobic materials at the initial stage, with cells showing a round shape and aggregating in clusters. However, over longer culture periods, cell proliferation is more advanced on more hydrophilic surfaces, where cells spread out with a flatter shape. Improvement of cell viability is observed with the addition of HA and HNTs.