bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantum dots‐based fluorescence resonance energy transfer biosensor for monitoring cell apoptosis
Authors: Gu Chunchuan 
Published: April 2017

AbstractThe development of advanced methods for accurately monitoring cell apoptosis has extensive significance in the diagnostic and pharmaceutical fields. In this study, we developed a rapid, sensitive and selective approach for the detection of cell apoptosis by combining the site‐specific recognition and cleavage of the DEVD–peptide with quantum dots (QDs)‐based fluorescence resonance energy transfer (FRET). Firstly, biotin‐peptide was conjugated on the surface of AuNPs to form AuNPs‐pep through the formation of an Au‐S bond. Then, AuNPs–pep–QDs nanoprobe was obtained through the connection between AuNPs–pep and QDs. FRET is on and the fluorescence of QDs is quenched at this point. The evidence of UV–vis spectra, transmission electron microscopy (TEM), and Fourier transform infrared (FT‐IR) spectroscopy revealed that the connection was successful. Upon the addition of apoptosis cell lysis solution, peptide was cleaved by caspase‐3, and AuNPs was dissociated from the QDs. At this time, FRET is off, and thus the QDs fluorescence was recovered. The experimental conditions were optimized in terms of ratio of peptide to AuNPs, buffer solution, and the temperature of conjugation and enzyme reaction. The biosensor was successfully applied to distinguishing apoptosis cells and normal cells within 2 h. This study demonstrated that the biosensor could be utilized to evaluate anticancer drugs.
Enhanced chemiluminescence for trazodone trace analysis based on acidic permanganate oxidation in concurrent presence of rhodamine 6G
Authors: Fujimori Keiichi , Sakata Yuta , Moriuchi‐Kawakami Takayo , Shibutani Yasuhiko 
Published: April 2017

AbstractA new sensitized chemiluminescence method by acidic permanganate oxidation was developed for the sensitive determination of trazodone. A fluorescent dye as used rhodamine 6G to increase a chemiluminescence intensity. Under optimum conditions, the liner range of the calibration curve was obtained for 1–5000 nmol/L. The limit of detection was calculated from 3σ of a blank was 0.23 nmol/L. The coexistent ions and substances had no interference with the chemiluminescence measurement. The chemiluminescence spectra were measured to elucidate a possible mechanism for the system. The present method was satisfactorily used in the determination of the drugs in pharmaceutical samples and animal serums.
A Designed ZnO@ZIF‐8 Core–Shell Nanorod Film as a Gas Sensor with Excellent Selectivity for H2 over CO
Authors: Wu Xiaonan , Xiong Shunshun , Mao Zhenghao , Hu Sheng , Long Xinggui 
Published: April 2017

AbstractThe development of H2 gas sensors is important for H2 production as a fuel. In this work, a ZnO@ZIF‐8 core–shell nanorod film is designed and synthesized as a gas sensor through a facile solution deposition process. This film shows an excellent selective response for H2 over CO. By fine‐tuning the reaction conditions, a ZnO@ZIF‐8 core–shell structure with a thin, fine‐grain, porous ZIF‐8 shell is obtained. Owing to the facile H2 penetration through the ZIF‐8 thin shell (≈110 nm) and the increased oxygen vacancies for the complex film, the ZnO@ZIF‐8 nanorod film shows a higher H2 sensitivity than a raw ZnO nanorod film. More importantly, the ZnO@ZIF‐8 nanorod film shows no response for CO at 200 °C. Because of the fine‐grain confinement of the porous ZIF‐8 shell (<140 nm), the molecular sieving effect is strengthened, which allows the effective separation of H2 over CO. This work provides a promising strategy for the design of high‐performance H2 sensors.
Assembling Porphyrins into Extended Network Structures by Employing Aromatic Dicarboxylates: Synthesis, Metal Exchange, and Heterogeneous Catalytic Studies
Authors: Dutta Gargi , Jana Ajay Kumar , Natarajan Srinivasan 
Published: April 2017

AbstractThree new metal–organic porphyrinic framework compounds of zinc and 5,10,15,20‐tetrakis(4‐pyridyl)porphyrin (TPyP) have been synthesized under solvothermal conditions. The compounds [Zn5(C40H24N8)(C8H4O4)2(NO3)6(DMA)2] (DMA)3(H2O)8 (1; DMA=dimethylacetamide), [Zn3(C40H24N8)(C8H4O4)2(DMF)](DMF)5(H2O)12 (2), and [Zn3(C40H24N8)(C12H6O4)2(DMA)2](H2O)7 (3) have two (1) and three dimensionally (2 and 3) extended structures. All the three structures contain porphyrinic units connected through the carboxylate linkers. The nitrates bind the metal centers and are not hydrogen bonded. The different binding modes of nitrate in the structure of 1 are observed for the first time in a porphyrin‐based MOF. The openness of the structure allowed us to explore metal exchange through a room‐temperature metathetic route. Compound 2 undergoes 100 % exchange with copper, whereas compound 3 exchanges 70 % with copper. The copper‐exchanged compounds Cu∈2 and Cu∈3 were observed to be good heterogeneous catalysts for many important organic reactions. The chemo and regioselective enamination of β‐ketoesters, preparation of propargylamine derivatives as well as regioselective cycloadditions of alkyne and azide (click reactions) have been carried out with good yields and selectivity. All the compounds have been characterized by PXRD, IR, UV/Vis, atomic absorption spectroscopy (AAS), and energy‐dispersive X‐ray spectroscopy (for Cu exchange).
A New Approach to Models of the 4,5‐Dihydroxycyclopentenone Core of the Kodaistatins A–D: Elucidation of the Diol Configuration in Kodaistatin A
Authors: Peter David , Brückner Reinhard 
Published: April 2017

AbstractThe kodaistatins A–D are strongly anti‐diabetic natural products from Aspergillus terreus that hold some promise of a novel diabetes cure. However, considerations of that kind face two drawbacks: 1) The kodaistatins A–D contain a heavily substituted pulvinone/cyclopentenone combination; 2) they are 1,2‐diols, the 3D structures of which have not been assigned yet. However, we can exclude two of the four possible stereostructures. We conclude that kodaistatin A is a trans‐, not a cis‐diol from NMR comparisons with a pair of cis, trans‐isomeric kodaistatin models, which we synthesized in 11 and 12 steps, respectively. The stereocenters of the diol moiety arose from stereocomplementary, highly diastereoselective aldol additions of a lithium enolate or the corresponding silyl ketene acetal. The cyclopentenone moieties stemmed from intramolecular aldol additions and ensuing dehydrations. The requisite enolates were obtained by the reduction of α‐bromoketones with samarium diiodide.
Highly Enantioselective Allylation of Ketones: An Efficient Approach to All Stereoisomers of Tertiary Homoallylic Alcohols
Authors: Brauns Marcus , Mantel Marvin , Schmauck Julie , Guder Marian , Breugst Martin , Pietruszka Jörg 
Published: April 2017

AbstractAn optimized protecting group for allylboronates allowed the use of ketones in order to synthesize all isomers of quaternary homoallylic alcohols with high enantioselectivities. All symmetric isomers of the allylboronate were prepared in high yields and diastereoselectivities using Sn2′ reactions. The improved reactivity of the novel protecting group was verified by following the reaction kinetics with 1H NMR spectroscopy. Mechanistic studies using DFT calculations were conducted to investigate the new findings. Thus, the stereochemical outcome and enhanced reactivity can be rationalized.
Liquid and subcritical fluid chromatographic enantioseparation of Nα‐Fmoc proteinogenic amino acids on Quinidine‐based zwitterionic and anion‐exchanger type chiral stationary phases. A comparative study
Authors: Lajkó Gyula , Grecsó Nóra , Tóth Gábor , Fülöp Ferenc , Lindner Wolfgang , Ilisz István , Péter Antal 
Published: April 2017

AbstractStereoselective high‐performance liquid chromatographic and subcritical fluid chromatographic separations of 19 Nα‐Fmoc proteinogenic amino acid enantiomers were carried out by using Quinidine‐based zwitterionic and anion‐exchanger‐type chiral stationary phases Chiralpak ZWIX(−) and QD‐AX. For optimization of retention and enantioselectivity, the ratio of bulk solvent components (MeOH/MeCN, H2O/MeOH, or CO2/MeOH) and the nature and concentration of the acid and base additives (counter‐ and co‐ions) were systematically varied. The effect of column temperature on the enantioseparation was investigated and thermodynamic parameters were calculated from the van't Hoff plots ln α vs. 1/T. The thermodynamic parameters revealed that the enantioseparations were enthalpy‐driven. The elution sequence was determined in all cases and with the exception of Fmoc‐Cys(Trt)‐OH, it was identical on both chiral stationary phases whereby the L‐enantiomers eluted before the D‐enantiomers.
Targeting DNA‐Dependent Protein Kinase for Cancer Therapy
Authors: Harnor Suzannah J. , Brennan Alfie , Cano Céline 
Published: April 2017

AbstractThe catalytic activity of DNA‐dependent protein kinase (DNA‐PK) is critical to its ability to repair lethal DNA double‐strand breaks (DSBs). This includes repair of DSB lesions resulting from oxidative stress, oncogene‐induced transcription, or following therapeutic treatment of cancer cells. Armed with this knowledge, many attempts have been made to identify small‐molecule inhibitors of DNA‐PK activity as an approach to induce tumour chemo‐ and radiosensitisation. This review examines the structures of known reversible and irreversible inhibitors, including those based on chromen‐4‐one, arylmorpholine, and benzaldehyde scaffolds. DNA‐PK catalytic inhibitors, such as VX‐984 (8‐[(1S)‐2‐[[6‐(4,6‐dideuterio‐2‐methylpyrimidin‐5‐yl)pyrimidin‐4‐yl]amino]‐1‐methylethyl]quinoline‐4‐carboxamide) and M3814 ((S)‐[2‐chloro‐4‐fluoro‐5‐(7‐morpholinoquinazolin‐4‐yl)phenyl]‐(6‐methoxypyridazin‐3‐yl)methanol), have now progressed into clinical development which should help to further advance our understanding of whether this approach is a promising therapeutic strategy for the treatment of cancer.
Facilitating the development of stencil applications using the Heterogeneous Programming Library
Authors: Viñas Moisés , Fraguela Basilio B. , Andrade Diego , Doallo Ramón 
Published: April 2017

SummaryStencil computations are very common in scientific codes. Heterogeneous systems achieve good results solving these problems, but their programming is complex because of the ghost regions required in multi‐device implementations and the difficulty to properly exploit their hardware. The Heterogeneous Programming Library (HPL) is a recent framework that improves the programmability of heterogeneous devices. This paper describes two extensions of HPL focused on stencil computations. The first one allows to automatically update the ghost regions they involve. The second one automates the implementation of the computational kernels of these algorithms. In our evaluation, the first mechanism reduces on average the number of lines of code and the Halstead programming effort of the host code of comparable HPL baselines by 34% and 64.2%, respectively, while the second contribution reduces these metrics by 72% and 79% in the computational kernels, respectively. Also, the first technique has negligible performance overheads, while the second one matches the performance of manually developed kernels. As an added benefit, the facilitation of the development of these codes thanks to these techniques helps programmers experiment with optimizations suited for this applications such as the ghost cell expansion technique, which provides speedups of up to 13% in our experiments.
Breaks in MODIS time series portend vegetation change: verification using long‐term data in an arid grassland ecosystem
Authors: Browning Dawn M. , Maynard Jonathan J. , Karl Jason W. , Peters Debra C. 
Published: April 2017

AbstractFrequency and severity of extreme climatic events are forecast to increase in the 21st century. Predicting how managed ecosystems may respond to climatic extremes is intensified by uncertainty associated with knowing when, where, and how long effects of extreme events will be manifest in an ecosystem. In water‐limited ecosystems with high inter‐annual variability in rainfall, it is important to be able to distinguish responses that result from seasonal fluctuations in rainfall from long‐term directional increases or decreases in precipitation. A tool that successfully distinguishes seasonal from directional biomass responses would allow land managers to make informed decisions about prioritizing mitigation strategies, allocating human resource monitoring efforts, and mobilizing resources to withstand extreme climatic events. We leveraged long‐term observations (2000–2013) of quadrat‐level plant biomass at multiple locations across a semiarid landscape in southern New Mexico to verify the use of Normalized Difference Vegetation Index (NDVI) time series derived from 250‐m Moderate Resolution Imaging Spectroradiometer (MODIS) data as a proxy for changes in aboveground productivity. This period encompassed years of sustained drought (2000–2003) and record‐breaking high rainfall (2006 and 2008) followed by subsequent drought years (2011 through 2013) that resulted in a restructuring of plant community composition in some locations. Our objective was to decompose vegetation patterns derived from MODIS NDVI over this period into contributions from (1) the long‐term trend, (2) seasonal cycle, and (3) unexplained variance using the Breaks for Additive Season and Trend (BFAST) model. BFAST breakpoints in NDVI trend and seasonal components were verified with field‐estimated biomass at 15 sites that differed in species richness, vegetation cover, and soil properties. We found that 34 of 45 breaks in NDVI trend reflected large changes in mean biomass and 16 of 19 seasonal breaks accompanied changes in the contribution to biomass by perennial and/or annual grasses. The BFAST method using satellite imagery proved useful for detecting previously reported ground‐based changes in vegetation in this arid ecosystem. We demonstrate that time series analysis of NDVI data holds potential for monitoring landscape condition in arid ecosystems at the large spatial scales needed to differentiate responses to a changing climate from responses to seasonal variability in rainfall.
Selecting habitat to what purpose? The advantage of exploring the habitat–fitness relationship
Authors: Uboni Alessia , Smith Douglas W. , Stahler Daniel R. , Vucetich John A. 
Published: April 2017

AbstractMeasures of reproductive success have been recognized in many fields as essential tools to assess the status of populations, species, and communities. However, difficulties in gathering data on reproductive success often prevent researchers from taking advantage of the information offered by those measures. For example, most of habitat selection studies do not include reproductive success in their analysis even though doing so would highly improve our understanding of the habitat selection process. In our study, we aimed to assess to what extent habitat selection choices made by adult individuals are directed to increase their annual reproductive success. We tested this idea by first developing habitat selection models and then relating the results of those models to two measures of reproductive success. Using wolves,Canis lupus, as the study species, we determined that not all habitat selection choices performed by adult wolves were related to their annual reproductive success. The results varied also in relation to the measure of reproductive success used in the analysis and other individual‐, group‐, and population‐level factors. Likely, adult female wolves select habitat characteristics to increase not only their annual reproductive success but also their lifetime reproductive success, for example, by ensuring their own survival and reproductive abilities in subsequent years. Our study suggests that a variety of motivations may govern habitat choices performed by adult individuals and including different measures of fitness in habitat selection studies can improve our understanding of these complex processes.
Ultrasensitive Label‐free Electrochemical Immunosensors for Multiple Cell Surface Biomarkers on Liver Cancer Stem Cells
Authors: Eissa Shimaa , Chinnappan Raja , Zourob Mohammed 
Published: April 2017

AbstractLiver cancer is one of the most widely spread cancers in the world. Cancer stem cells (CSCs) are a small subpopulation of liver cancer cells that are thought to be responsible for relapse of cancer and the resistance to chemotherapy. Detection of CSCs is highly demanded for screening patients who are at high risk for developing metastatic cancers. However, the current methodologies for CSCs detection are sophisticated, expensive and not reliable. Here, we report the development of a label‐free impedance immunosensors for liver CSC quantification using four established CSC surface biomarkers (CD44, CD90, CD133/2 and OV‐6). The immunosensors were simply fabricated by the covalent attachment of four biomarkers specific antibodies on gold electrodes using cysteamine/phenylene isothiocyanate linker. Electrochemical impedance spectroscopy was employed to detect the binding of the cells to the immunosensors. The binding of the CSCs to the gold electrode surface retards the access of ferri‐ferrocyanide redox molecules to the electrode leading to enhancement in the charge transfer resistance (Rct) which represents the basis of the detection signal. The developed electrochemical immunosensors showed high sensitivity and selectivity for CSC detection with a wide linear range from 1 × 101 to 1× 104 cells/mL with a limit of detection of 1 cell/ml. This work represents a new, accurate, simple and low cost method for the detection of liver CSC that might help in the early diagnosis of metastatic disease and cancer relapse.
Computing the force distribution on the surface of complex, deforming geometries using vortex methods and Brinkman penalization
Authors: Verma Siddhartha , Abbati Gabriele , Novati Guido , Koumoutsakos Petros 
Published: April 2017

SummaryThe distribution of forces on the surface of complex, deforming geometries is an invaluable output of flow simulations. One particular example of such geometries involves self‐propelled swimmers. Surface forces can provide significant information about the flow field sensed by the swimmers and are difficult to obtain experimentally. At the same time, simulations of flow around complex, deforming shapes can be computationally prohibitive when body‐fitted grids are used. Alternatively, such simulations may use penalization techniques. Penalization methods rely on simple Cartesian grids to discretize the governing equations, which are enhanced by a penalty term to account for the boundary conditions. They have been shown to provide a robust estimation of mean quantities, such as drag and propulsion velocity, but the computation of surface force distribution remains a challenge. We present a method for determining flow‐induced forces on the surface of both rigid and deforming bodies, in simulations using remeshed vortex methods and Brinkman penalization. The pressure field is recovered from the velocity by solving a Poisson's equation using the Green's function approach, augmented with a fast multipole expansion and a tree‐code algorithm. The viscous forces are determined by evaluating the strain‐rate tensor on the surface of deforming bodies, and on a “lifted” surface in simulations involving rigid objects. We present results for benchmark flows demonstrating that we can obtain an accurate distribution of flow‐induced surface forces. The capabilities of our method are demonstrated using simulations of self‐propelled swimmers, where we obtain the pressure and shear distribution on their deforming surfaces.
Unified gas kinetic scheme combined with Cartesian grid method for intermediate Mach numbers
Authors: Ragta Lokesh Kumar , Srinivasan Balaji , Sinha Sawan S. 
Published: April 2017

SummaryWe develop a method to seamlessly simulate flows over a wide range of Knudsen numbers past arbitrarily shaped immersed boundaries. To achieve seamless computation, ie, not use any zone division to distinguish between continuum and non‐continuum regions, we use the unified gas kinetic scheme (UGKS), which is based on the Bhatnagar‐Groos‐Krook (BGK) approximation of the Boltzmann equation. We combine UGKS with an appropriately designed Cartesian grid method (CGM) to allow us to compute flows past arbitrary boundaries. The CGM we use here satisfies boundary conditions at the wall by using a constrained least square interpolation procedure. However, it differs from the usual, continuum CGMs in 2 ways. Firstly, to allow us capture non‐continuum effects at the boundaries, the CGM used herein interpolates the microscopic velocity distribution function in addition to the macroscopic variables. Secondly, even for the macroscopic variables, we use a gas kinetic method–based density interpolation procedure at the boundaries that allows the CGM to interface well with the UGKS method. We demonstrate the robustness and efficacy of the method by testing it on stationary immersed boundaries at various Knudsen numbers ranging from continuum to transition regimes.
The impact of maternal employment on children's adiposity: Evidence from China's labor policy reform
Authors: Jo Young , Wang Qing 
Published: April 2017

AbstractBackgroundChina has experienced a rapid growth in childhood adiposity in recent years. Although a large number of studies examine the effect of maternal employment on children's adiposity in developed countries, only a few studies investigate the issue in developing countries. Moreover, existing studies tend to suffer from a potential endogeneity issue.AimsWe provide new evidence on the causal effect of maternal employment on children's adiposity in China.Materials and methodsWe employ a difference‐in‐difference strategy that takes advantage of China's 1995 legislative change to labor regulations, which reduced the number of workdays from 6 to 5 days per week. Using longitudinal data from the China Health and Nutrition Survey (CHNS), we compare children whose mothers are wage‐earning employees to those whose mothers are self‐employed because the reform only affected the former.ResultsAlthough maternal employment and childhood obesity in China exhibits the same positive association as in the United States, our difference‐in‐difference estimates present a different picture. We find that a reduction in the maternal labor supply led to children's weight gain. Further investigation reveals that the effect was stronger among children who were male, younger, in urban areas, and from households with low socioeconomic status.DiscussionOur evidence suggests that a change in maternal behaviors was likely responsible for children's weight gain. In particular, a greater proportion of treatment group mothers cooked and also devoted more time to cooking after the reform, which led to an increased caloric intake by their children. Such weight gain was beneficial for children who were previously underweight but harmful to those who became overweight.ConclusionThe finding implies that additional maternal time at home likely has a different effect in China compared to the United States.