bluuebunny/crossref_metadata_2025_split huggingface dataset:
Free‐base porphyrins as CEST MRI contrast agents with highly upfield shifted labile protons
Authors: Zhang Xiaoxiao , Yuan Yaping , Li Sha , Zeng Qingbin , Guo Qianni , Liu Na , Yang Minghui , Yang Yunhuang , Liu Maili , McMahon Michael T. , Zhou Xin 
Published: April 2019

PurposeCEST has become a preeminent technology for the rapid detection and grading of tumors, securing its widespread use in both laboratory and clinical research. However, many existing CEST MRI agents exhibit a sensitivity limitation due to small chemical shifts between their exchangeable protons and water. We propose a new group of CEST MRI agents, free‐base porphyrins and chlorin, with large exchangeable proton chemical shifts from water for enhanced detection.MethodsTo test these newly identified CEST agents, we acquired a series of Z‐spectra at multiple pH values and saturation field strengths to determine their CEST properties. The data were analyzed using the quantifying exchange using saturation power method to quantify exchange rates. After identifying several promising candidates, a porphyrin solution was injected into tumor‐bearing mice, and MR images were acquired to assess detection feasibility in vivo.ResultsBased on the Z‐spectra, the inner nitrogen protons in free‐base porphyrins and chlorin resonate from −8 to −13.5 ppm from water, far shifted from the majority of endogenous metabolites (0‐4 ppm) and Nuclear Overhauser enhancements (−1 to −3.5 ppm) and far removed from the salicylates, imidazoles, and anthranillates (5‐12 ppm). The exchange rates are sufficiently slow to intermediate (500‐9000 s−1) to allow robust detection and were sensitive to substituents on the porphyrin ring.ConclusionThese results highlight the capabilities of free‐base porphyrins and chlorin as highly upfield CEST MRI agents and provide a new scaffold that can be integrated into a variety of diagnostic or theranostic agents for biomedical applications.
Trade credit contract in the presence of retailer investment opportunity
Authors: Zha Yong , Chen Kehong , Yue Xiaohang , Yu Yugang , Mukhopadhyay Samar 
Published: April 2019

AbstractThis paper presents a model for designing a trade credit contract between a supplier and a retailer that would coordinate a supply chain in the presence of investment opportunity for the retailer. Specifically, we study a newsvendor model where the supplier offers a trade credit contract to the retailer who, by delaying the payment, can invest the accounts payable amount and earn returns. We find that when the channel partners have symmetric information about the retailer's investment return, a conditionally concessional trade credit (CTC) contract, which includes a wholesale price, an interest‐free period, and a minimum order requirement, can achieve channel coordination. We then extend the model to the information asymmetry setting in which the retailer's investment return is unobservable by the supplier. We show that, although the CTC contract cannot achieve the coordination in this setting, it can effectively improve channel efficiency as well as profitability for individual partners.
Metabolism of hyperpolarized 13C‐acetoacetate to β‐hydroxybutyrate detects real‐time mitochondrial redox state and dysfunction in heart tissue
Authors: Chen Wei , Sharma Gaurav , Jiang Weina , Maptue Nesmine R. , Malloy Craig R. , Sherry A. Dean , Khemtong Chalermchai 
Published: April 2019

Mitochondrial dysfunction is considered to be an important component of many metabolic diseases yet there is no reliable imaging biomarker for monitoring mitochondrial damage in vivo. A large prior literature on inter‐conversion of β‐hydroxybutyrate and acetoacetate indicates that the process is mitochondrial and that the ratio reflects a specifically mitochondrial redox state. Therefore, the conversion of [1,3‐13C]acetoacetate to [1,3‐13C]β‐hydroxybutyrate is expected to be sensitive to the abnormal redox state present in dysfunctional mitochondria.In this study, we examined the conversion of hyperpolarized (HP) 13C‐acetoacetate (AcAc) to 13C‐β‐hydroxybutyrate (β‐HB) as a potential imaging biomarker for mitochondrial redox and dysfunction in perfused rat hearts. Conversion of HP‐AcAc to β‐HB was investigated using 13C magnetic resonance spectroscopy in Langendorff‐perfused rat hearts in four groups: control, global ischemic reperfusion, low‐flow ischemic, and rotenone (mitochondrial complex‐I inhibitor)‐treated hearts.We observed that more β‐HB was produced from AcAc in ischemic hearts and the hearts exposed to complex I inhibitor rotenone compared with controls, consistent with the accumulation of excess mitochondrial NADH. The increase in β‐HB, as detected by 13C MRS, was validated by a direct measure of tissue β‐HB by 1H nuclear magnetic resonance in tissue extracts. The redox ratio, NAD+/NADH, measured by enzyme assays of homogenized tissue, also paralleled production of β‐HB from AcAc. Transmission electron microscopy of tissues provided direct evidence for abnormal mitochondrial structure in each ischemic tissue model.The results suggest that conversion of HP‐AcAc to HP‐β‐HB detected by 13C‐MRS may serve as a useful diagnostic marker of mitochondrial redox and dysfunction in heart tissue in vivo.
Enhancing piecewise‐defined surrogate response surfaces with adjoints on sets of unstructured samples to solve stochastic inverse problems
Authors: Mattis Steven A. , Butler Troy 
Published: April 2019

SummaryMany approaches for solving stochastic inverse problems suffer from both stochastic and deterministic sources of error. The finite number of samples used to construct a solution is a common source of stochastic error. When computational models are expensive to evaluate, surrogate response surfaces are often employed to increase the number of samples available for approximating the solution. This leads to a reduction in finite sampling errors while the deterministic error in the evaluation of each sample is potentially increased. The pointwise accuracy of sampling the surrogate is primarily impacted by two sources of deterministic error: the local order of accuracy in the surrogate and the numerical error from the numerical solution of the model. In this work, we use adjoints to simultaneously give a posteriori error and derivative estimates in order to construct low‐order, piecewise‐defined surrogates on sets of unstructured samples. Several examples demonstrate the computational gains of this approach in obtaining accurate estimates of probabilities for events in the design space of model input parameters. This lays the groundwork for future studies on goal‐oriented adaptive refinement of such surrogates.
Preparation of ZrO2/silicone hybrid materials for LED encapsulation via in situ sol‐gel reaction
Authors: Huang Yufeng , Feng Yakai , Sun Xujun , Han Ying , Liu Dongshun , Tan Xiaohua 
Published: April 2019

Organic silicones have been used as encapsulant materials for light‐emitting diodes (LEDs) for many years, while their performances need to be improved in order to satisfy the requirements of high‐power LEDs. A ZrO2/silicone hybrid resin (ZHR) was synthesized for LEDs encapsulation by in situ sol‐gel reactions. The oligosiloxane was synthesized as polymeric matrix by nonaqueous sol‐gel condensation using diphenylsilanediol (DPSD), vinyltrimethoxysilane (VTMS), and 3‐methacryloxy propyl trimethoxysilane (MPTMS) as monomers. Then zirconium propoxide was added into this polymeric matrix to be hydrolyzed to obtain the hybrid resin with a uniform dispersion of ZrO2 nanoparticles. The Si–O–Zr covalent bond was detected and benefited for excellent dispersibility of the ZrO2 nanoparticles and the well compatibility between organic and inorganic phases. The cured ZHR with 5 wt% ZrO2 content showed high light transmittance (greater than 80% in visible light range), high refractive index (=1.56), and high thermal stability (no yellowing at 150°C for 240 hours). The luminous flux of the LED chip with ZHR encapsulant was 10% higher than that of the pure silicone resin, suggesting that ZHR has great application potential in the field of LED packaging.
Role of the extent of prophylactic regional lymph node radiotherapy on survival in high‐risk neuroblastoma: A report from the COG A3973 study
Authors: Braunstein Steve E. , London Wendy B. , Kreissman Susan G. , Villablanca Judith G. , Davidoff Andrew M. , DeSantes Kenneth , Castleberry Robert P. , Murray Kevin , Diller Lisa , Matthay Katherine , Cohn Susan L. , Shulkin Barry , von Allmen Daniel , Parisi Marguerite T. , Van Ryn Collin , Park Julie R. , La Quaglia Michael P. , Haas‐Kogan Daphne A. 
Published: April 2019

AbstractPurposeNeuroblastoma is the most common extracranial solid pediatric malignancy, with poor outcomes in high‐risk disease. Standard treatment approaches employ an increasing array of aggressive multimodal therapies, of which local control with surgery and radiotherapy remains a backbone; however, the benefit of broad regional nodal irradiation remains controversial. We analyzed centrally reviewed radiation therapy data from patients enrolled on COG A3973 to evaluate the impact of primary site irradiation and the extent of regional nodal coverage stratified by extent of surgical resection.MethodsThree hundred thirty high‐risk neuroblastoma patients with centrally reviewed radiotherapy plans were analyzed. Outcome was evaluated by the extent of nodal irradiation. For the 171 patients who also underwent surgery (centrally reviewed), outcome was likewise analyzed according to the extent of resection. Overall survival (OS), event‐free survival (EFS), and cumulative incidence of local progression (CILP) were examined by Kaplan–Meier, log‐rank test (EFS, OS), and Grey test (CILP).ResultsThe five‐year CILP, EFS, and OS for all 330 patients receiving radiotherapy on A3973 were 8.5% ± 1.5%, 47.2% ± 3.0%, and 59.7% ± 3.0%, respectively. There were no significant differences in outcomes based on the extent of lymph node irradiation regardless of the degree of surgical resection (< 90% or ≥90%).ConclusionAlthough local control remains a significant component of treatment of high‐risk neuroblastoma, our results suggest there is no benefit of extensive lymph node irradiation, irrespective of the extent of surgical resection preceding stem cell transplant.
Effect of side chain and backbone length on lamellar spacing in polystyrene‐block‐poly(dimethyl siloxane) brush block copolymers
Authors: Fei Huafeng , Yavitt Benjamin M. , Kopanati Gayathri , Watkins James J. 
Published: April 2019

ABSTRACTWe report the synthesis of polystyrene‐block‐poly(dimethyl siloxane) (PS‐b‐PDMS) brush block copolymers (BBCPs) through sequential ROMP of norbornene‐modified macromonomers (‐NB) and explore the effect of side chain length (Nsc) and total backbone degree of polymerization (Nbb) on the self‐assembly of lamellar morphologies. Group I (PS‐NB Mn = 2.9 kg/mol, PDMS‐NB Mn = 4.8 kg/mol) exhibits asymmetric side chains, while Group II (PS‐NB Mn = 4.7 kg/mol, PDMS‐NB Mn = 4.8 kg/mol) possess a more symmetric arrangement. Both families rapidly self‐assemble into well‐ordered lamellar morphologies with domain spacings (d0) ranging from d0 = 54 to 140 nm. The scaling relationship between d0 and Nbb (d0 ~Nbbα) was determined as the measure of backbone flexibility. Exponents of α = 0.71 and α = 0.81 are observed for Groups I and II, respectively, indicating the BBCPs adopt an extended backbone conformation. The presence of a low Tg side chain such as PDMS increases apparent flexibility of the backbone. The interplay between contrasting characteristics of the side chains is discussed and reveals the importance of understanding the physical consequences of block architecture on controlling BBCP assembly. These findings provide necessary information for future investigations of complex phases and well‐defined nanostructures fabricated using the brush architecture. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 691–699
Self‐Assemble Polymeric Nanoparticle with GSH Exhaustion for SPECT Imaging–Guided Enhanced Radioisotope Therapy
Authors: Tao Yugui , Ren Pengfei , Yi Xuan , Zhou Hailin , Xiong Saisai , Ge Fei , Chen Lei , Yang Kai 
Published: April 2019

AbstractExploiting biocompatible nanomaterials for cancer theranostics has attracted great attention in recent years. Herein, a multifunctional self‐assembled nanoparticle based on a biocompatible polymer that contains 3‐(4‐hydroxyphenyl) propionic acid N‐hydroxysuccinimide ester (HOPA) for radiolabeling and piperlongumine (PL) for exhausting endogenous glutathione (GSH) (HOPA‐C18PMH‐PEG/PL) is successfully synthesized. With radionuclide 125I labeling, SPECT imaging shows high tumor uptake of HOPA‐C18PMH‐PEG/PL after intravenous injection. The in vitro and in vivo combined radioisotope therapy (RIT) and chemotherapy using 131I‐labeled HOPA‐C18PMH‐PEG/PL is then carried out, achieving synergistic antitumor effect. This is because the reactive oxygen species (ROS) level in the tumor sites of mice treated with 131I‐labeled HOPA‐C18PMH‐PEG/PL is increased after the exhaustion of GSH by PL. Additionally, such a strategy (exhausting GSH and increasing ROS) induces no obvious toxicity to normal tissue. Therefore, as‐made polymeric nanoparticles exhibit multifunctional properties for SPECT imaging–guided combined RIT and chemotherapy in one system. This finding will further promote polymeric nanoparticle–based RIT of cancer and is expected to be used for future clinical transformation.
Catalytic triad heterogeneity in S51 peptidase family: Structural basis for functional variability
Authors: Yadav Pooja , Goyal Venuka Durani , Chandravanshi Khileshwari , Kumar Ashwani , Gokhale Sadashiv M. , Jamdar Sahayog N. , Makde Ravindra D. 
Published: April 2019

AbstractPeptidase E (PepE) is a nonclassical serine peptidase with a Ser‐His‐Glu catalytic triad. It is specific for dipeptides with an N‐terminal aspartate residue (Asp‐X dipeptidase activity). Its homolog from Listeria monocytogenes (PepElm) has a Ser‐His‐Asn “catalytic triad.” Based on sequence alignment we predicted that the PepE homolog from Deinococcus radiodurans (PepEdr) would have a Ser‐His‐Asp “catalytic triad.” We confirmed this by solving the crystal structure of PepEdr to 2.7 Å resolution. We show that PepElm and PepEdr lack the Asp‐X dipeptidase activity. Our analyses suggest that absence of P1 pocket in the active site could be the main reason for this lack of typical activity. Sequence and structural data reveal that the PepE homologs can be divided into long and short PepEs based on presence or absence of a C‐terminal tail which adopts a β‐hairpin conformation in the canonical PepE from Salmonella enterica. A long PepE from Bacillus subtilis with Ser‐His‐Asp catalytic triad exhibits Asp‐X dipeptidase activity. Whereas the three long PepEs enzymatically characterized till date have been found to possess the Asp‐X dipeptidase activity, the three enzymatically characterized short PepEs lack this activity irrespective of the nature of their catalytic triads. This study illuminates the structural and functional heterogeneity in the S51 family and also provides structural basis for the functional variability among PepE homologs.
Employment, education, and family: Revealing the motives behind internal migration in Great Britain
Authors: Thomas Michael J. 
Published: April 2019

AbstractDistinctions between internal migration and residential mobility are often formed with reference to assumed differences in motivation, with migration typically linked to employment and educational motives and shorter distance mobility to housing and family. Using geocoded microdata, this article reveals how employment‐led migration represents only a minority share (≈30%) of total migration events over 40 km. Family motives appear just as important, even at distances ≥100 km, with the desire to live closer to non‐resident family/friends being the most frequently cited family submotive. Estimated propensities to undertake employment and educational‐related migration fit very closely to predictions of human capital models of migration, being highest among young, residentially flexible and highly educated individuals. Migrants citing family‐related motives are disproportionately drawn from midlife and later‐life phases, with family shown to be a key motive among migrants with care‐related needs (e.g., parents with children) or access to fewer resources (e.g., social renters and low educational attainment).
Assessing the performance of object‐oriented LiDARpredictors for forest bird habitat suitability modeling
Authors: Glad Anouk , Reineking Björn , Montadert Marc , Depraz Alexandra , Monnet Jean‐Matthieu 
Published: April 2019

AbstractHabitat suitability models (HSMs) are widely used to plan actions for species of conservation interest. Models that will be turned into conservation actions need predictors that are both ecologically pertinent and fit managers’ conceptual view of ecosystems. Remote sensing technologies such as light detection and ranging (LiDAR) can describe landscapes at high resolution over large spatial areas and have already given promising results for modeling forest species distributions. The point‐cloud (PC) area‐based LiDARvariables are often used as environmental variables inHSMs and have more recently been complemented by object‐oriented (OO) metrics. However, the efficiency of each type of variable to capture structural information on forest bird habitat has not yet been compared. We tested two hypotheses: (1) the use ofOOvariables inHSMs will give similar performance asPCarea‐based models; and (2)OOvariables will improve model robustness to LiDARdatasets acquired at different times for the same area. Using the case of a locally endangered forest bird, the capercaillie (Tetrao urogallus), model performance and predictions were compared between the two variable types. Models usingOOvariables showed slightly lower discriminatory performance thanPCarea‐based models (average ΔAUC = −0.032 and −0.01 for females and males, respectively).OO‐based models were as robust (absolute difference in Spearman rank correlation of predictions ≤ 0.21) or more robust thanPCarea‐based models. In sum, LiDAR‐derivedPCarea‐based metrics andOOmetrics showed similar performance for modeling the distribution of the capercaillie. We encourage the further exploration ofOOmetrics for creating reliableHSMs, and in particular testing whether they might help improve the scientist–stakeholder interface through better interpretability.
Investigation of Empirical and Semi‐Empirical Charges to Study the Effects of Partial Charges on Quality and Prediction Accuracy in 3D‐QSAR
Authors: Babu Sathya , Nagarajan Santhosh Kumar , Madhavan Thirumurthy 
Published: April 2019

AbstractIn Quantitative Structure‐Activity Relationship (QSAR) studies, selection of an appropriate method to assign the partial charge is crucial to derive a reliable model. The prediction accuracy of 3D‐QSAR models depends mainly on the method by which the partial charges were calculated. Therefore, we are interested in examining the effects of empirical and semi‐empirical partial charges on 3D‐QSAR methods, Comparative Molecular Field Analysis (CoMFA) and Comparative Molecular Similarity Indices Analysis (CoMSIA). The feasibility and performance of these charges have been tested on Janus Kinase 2 inhibitors. Both empirical (Gasteiger‐Huckel, Del‐Re, Gasteiger Marsili, Huckel, Merck Molecular Force Field 94 (MMFF94), Pullman) and semi‐empirical (Austin Model 1 (AM1), Parameterized Model 3 (PM3), Recife Model 1 (RM1), and Modified Neglect of Diatomic Overlap (MNDO)) charges exhibited statistically significant quality. Among them, MMFF94, MNDO and AM1 charges yielded higher cross‐validation correlation coefficient (q2) values whereas Del‐Re and MMFF94 charges produced topmost predictive ability (r2pred). Overall, MMFF94 in CoMFA and MMFF94 and MNDO in CoMSIA models was found to be the best charges when both q2 and r2pred values were used as an evaluation criterion. Our results could provide an idea of selection of appropriate charge rather than using default charge to enhance the quality of 3D‐QSAR when prediction accuracy and predictive ability were employed.
Enhanced Surface Properties of Hydroxyapatite by Grafting Tartaric Acid for Sustained Release of Moxifloxacin
Authors: Zarif Faiza , Sharif Faiza , Batool Madeeha , Haider Ammar , Gul Urooj , Gilani Mazhar A. , Idrees Ayesha , Tabassum Sobia 
Published: April 2019

AbstractGrafting of material with organic functionalities helps to tune material's surface properties. Surface properties of a biomaterial play a significant role for sustained release of therapeutic agent. To evaluate the effect of tartaric acid concentration on HA surface properties and phase purity, a series of tartaric acid grafted HA (t‐HA) samples were prepared via in situ wet chemical synthesis. Grafting of HA with tartaric acid improved its surface properties. The surface area of 737 m2/g was gained when 0.05 mole equivalent of tartaric acid was used for HA grafting. X‐ray diffraction patterns of t‐HA samples have shown low degree of crystallinity compared to HA sample. XRD results showed the formation of calcium tartrate phase along with HA when higher concentration of tartaric acid was used for synthesis. The HA and t‐HA samples were explored for the delivery of moxifloxacin. High surface area, surface charge and low degree of crystallinity have improved electrostatic interaction between the drug and t2‐HA and help in sustained release of moxifloxacin. In vitro antibacterial activity of drug loaded samples showed activity against S. aureus. Calcium tartrate containing samples t3‐HA, t4‐HA and t5‐HA showed, however, moderate inhibition against S. aureus without drug. In vitro cell studies by using MC3T3 cell line showed that prepared HA and t‐HA samples did not exhibit any cytotoxic effect.
A Sensor Based on Hollow, Octahedral, Cu2O‐Supported Palladium Nanoparticles – Prepared by a Galvanic Replacement Reaction – and Carboxylic Multi‐Walled Carbon Nanotubes for Electrochemical Detection of Caffeic Acid in Red Wine
Authors: Hu Bibo , Zhang Min , Liu Peng , Xie Shilei , Xie Dong , Wang Shoushan , Cheng Faliang , Wang Lishi 
Published: April 2019

AbstractA novel nanocomposites prepared from hollow, octahedral cuprous oxide supported palladium nanoparticles (Cu2O‐PdNPs) through a facile galvanic replacement reaction and carboxylic multi‐walled carbon nanotubes (MWCNTs‐COOH) was modified on the surface of glassy carbon electrode (Cu2O‐PdNPs@MWCNTs‐COOH/GCE) to fabricate a sensor for electrochemical detection of caffeic acid. The synergistic effect between Cu2O‐PdNPs and MWCNTs‐COOH exhibited remarkable electrocatalytic activity, higher selectivity and higher sensitivity toward caffeic acid. At optimized test conditions, the Cu2O‐PdNPs@MWCNTs‐COOH/GCE nanocomposites sensor revealed wider linear range of 0.006‐60 μM with a lower detection limit of 0.002 μM (S/N=3) for caffeic acid determination. Eventually, the proposed nanocomposites sensor was successfully applied to determine the concentration of caffeic acid in red wine samples.