bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemoinformatic design of amphiphilic molecules for methane hydrate inhibition
Authors: Di Profio Pietro , Canale Valentino , Marvulli Francesca , Zappacosta Romina , Fontana Antonella , Siani Gabriella , Germani Raimondo 
Published: January 2018

AbstractCationic surfactants and other low molecular weight compounds are known to inhibit nucleation and agglomeration of methane hydrates. In particular, tetralkylammonium salts are kinetic hydrate inhibitors; ie, they reduce the rate of hydrate formation. This work relates to the in‐silico determination of structural features of molecules modulating methane hydrate formation, as found experimentally, and the prediction of novel structures to be tested as candidate inhibitors. Experimental data for each molecule are the amount of absorbed methane. By inserting these numerical values into a chemoinformatic model, it was possible to find a mutual correlation between structural features and inhibition properties. A maximum amount of information is extracted from the structural features and experimental variables, and a model is generated to explain the relationship therebetween. Chemometric analysis was performed by using the software package Volsurf+ with the aim of finding a primary correlation between surfactant structures and their properties. Experimental parameters (pressure, temperature, and concentration) were further processed through an optimization procedure.A careful study of the chemometric analysis responses and the numerical descriptors of tested surfactants allowed to define the features of a good inhibitor, as far as the amount of absorbed gas is concerned. An external prediction is finally made to project external compounds, whose structures and critical micellar concentration are known, in a statistical model, to predict the inhibition properties of a particular molecule in advance of synthesis and testing. This method allowed to find novel amphiphilic molecules for testing as candidate inhibitors in flow‐assurance.
Exploring the Effect of Polypyridyl Ligands on the Anticancer Activity of Phosphorescent Iridium(III) Complexes: From Proteosynthesis Inhibitors to Photodynamic Therapy Agents
Authors: Pracharova Jitka , Vigueras Gloria , Novohradsky Vojtech , Cutillas Natalia , Janiak Christoph , Kostrhunova Hana , Kasparkova Jana , Ruiz José , Brabec Viktor 
Published: January 2018

AbstractA series of five kinetically inert bis‐cyclometalated IrIII complexes of general formula [Ir(C^N)2(N^N)][PF6] [C^N=2‐phenyl‐1‐[4‐(trifluoromethyl)benzyl]‐1H‐benzo[d]imidazol‐κN,C; N^N=1,10‐phenanthroline (phen, 1), dipyrido[3,2‐d:2′,3′‐f]quinoxaline (dpq, 2), dipyrido[3,2‐a:2′,3′‐c]phenazine (dppz, 3), benzo[i]dipyrido[3,2‐a:2′,3′‐c]phenazine (dppn, 4), and dipyrido[3,2‐a:2′,3′‐c]phenazine‐10,11‐imidazolone (dppz‐izdo, 5)] were designed and synthesized to explore the effect of the degree of π conjugation of the polypyridyl ligand on their toxicity in cancer cells. We show that less‐lipophilic complexes 1 and 2 exhibit the highest toxicity [sub‐micromolar inhibitory concentration (IC50) values] in A2780, HeLa, and MCF‐7 cancer cells, and they are markedly more efficient than clinically used platinum drugs. It is noteworthy that the investigated Ir agents display the capability to overcome acquired and inherent resistance to conventional cisplatin (in A2780cisR and MCF‐7 cells, respectively). We demonstrate that the Ir complexes, unlike clinically used platinum antitumor drugs, do not kill cells through DNA‐damage response. Rather, they kill cells by inhibiting protein translation by targeting preferentially the endoplasmic reticulum. Our findings also reveal that the toxic effect of the Ir complexes can be significantly potentiated by irradiation with visible light (by more than two orders of magnitude). The photopotentiation of the investigated Ir complexes can be attributed to a marked increase (≈10–30‐fold) in intracellular reactive oxygen species. Collectively, these data highlight the functional diversity of antitumor metal‐based drugs and the usefulness of a mechanism‐based rationale for selecting candidate agents that are effective against chemoresistant tumors for further preclinical testing.
Prebiotic Chemistry of HCN Tetramerization by Automated Reaction Search
Authors: Nandi Surajit , Bhattacharyya Debankur , Anoop Anakuthil 
Published: January 2018

AbstractHCN oligomerization is considered to be one of the important pathways in chemical evolution. Nucleobases, aminoacids, and many other complex organic molecules can evolve through this pathway. We report an explorative study based on an automated reaction search method that avoids the cognitive bias present when searching chemical reaction space. We discuss the chemical space of the HCN dimer in detail, and the important trimers and tetramers are discussed briefly. A component‐wise molecular‐fingerprint‐based methodology is proposed to identify molecular similarity. We present four different thermal routes to cis/trans‐2,3‐diaminomaleonitrile and 4‐amino‐1H‐imidazole‐5‐carbonitrile, which are important intermediates in prebiotic chemistry.
Synthesis and Properties of Triaminocyclopropenium Cation Based Ionic Liquids as Hypergolic Fluids
Authors: Jin Yunhe , Wang Binshen , Zhang Wenquan , Huang Shi , Wang Kangcai , Qi Xiujuan , Zhang Qinghua 
Published: January 2018

AbstractA novel family of hydrophobic triaminocyclopropenium cation based ionic liquids have been synthesized, and their structures and physicochemical properties characterized by NMR and IR spectroscopy, elemental analysis, differential scanning calorimetry, and hypergolic tests. The experimental results showed that all of these ionic liquids exhibited the expected hypergolic reactivity with the oxidizer white fuming nitric acid. Among them, the hypergolic ionic liquid based on the cyanoimidazolylborohydride anion showed excellent integrated properties, including high decomposition temperature (194 °C), high density (0.95 g cm−3), moderate viscosity (44 MPa s), ultrafast ignition delay time (6 ms), and high specific impulse (301.9 s); this demonstrates its potential as an environmentally friendly alternative to toxic hydrazine derivatives.
Direct Dimethyl Ether Synthesis: Modelling of the Kinetics from Isothermal, Experimental Data
Authors: Henrich Till , Abeln Johannes , Betz Mathias 
Published: January 2018

AbstractDie einstufige Synthese von Dimethylether (DME) stellt eine Prozessintensivierung dar. Aufgrund der hohen Exothermie der Reaktion ist die genaue Kenntnis der kinetischen Parameter notwendig. Als Katalysator wurde eine Mischung zweier kommerziell erhältlicher Katalysatoren eingesetzt. Die Experimente wurden bei 50 bar und von 220 bis 280 °C durchgeführt. Das isotherme Verhalten wurde durch Messung axialer Temperaturprofile verifiziert. Aus den experimentellen Daten konnten die kinetischen Parameter, unter Berücksichtigung von Thermodynamik und Realgasverhalten, berechnet werden.
Continuous Countercurrent Extractive Biocatalysis in Aqueous Surfactant Two‐Phase Systems
Authors: Ritter Eric , Smirnova Irina 
Published: January 2018

AbstractTo evaluate the possibility of performing extractive biocatalysis in continuous mode, the hydrolysis of penicillin G in a micellar solution containing the nonionic surfactant Tergitol NP‐7 was chosen as model system. While the product phenylacetic acid distributes into the micellar phase, 6‐aminopenicillanic acid moves preferably into the aqueous phase. The yield in the continuous multi‐step process was higher in comparison to equivalent batch systems. Overall, the results demonstrate the suitability of aqueous surfactant two‐phase systems for continuous biocatalytic reactive extraction processes.
Survival by Hispanic ethnicity among patients with cancer participating in SWOG clinical trials
Authors: Chavez‐MacGregor Mariana , Unger Joseph M. , Moseley Anna , Ramsey Scott D. , Hershman Dawn L. 
Published: January 2018

BACKGROUNDRacial disparities in cancer outcomes have been described. To the authors' knowledge, it remains unclear whether patients of Hispanic ethnicity have better or worse survival outcomes. In the current study, the authors evaluated whether Hispanic participants in SWOG clinical trials had different survival outcomes compared with non‐Hispanics.METHODSAdult patients registered in SWOG phase 2/3 clinical trials between 1986 and 2012 were analyzed. Studies of similar histology and stage of disease were combined. Within each analysis, Kaplan‐Meier survival curves were generated to examine differences in outcome by ethnicity. Multivariate Cox regression was used to estimate the association between ethnicity and survival outcomes, controlling for major disease‐specific prognostic factors and demographic variables plus area‐level income and education to account for socioeconomic status.RESULTSA total of 29,338 patients registered to 38 trials were included; 5% of these patients were Hispanic. Hispanic patients were more likely to be younger and from areas of lower income and education (all P<.05). No differences in survival were observed across tumor types except in the patients with advanced stage prostate cancer, in whom the authors observed an association between Hispanic ethnicity and worse overall survival (hazard ratio [HR], 1.40; P = .006), progression‐free survival (HR, 1.36; P = .007), and cancer‐specific survival (HR, 1.42; P = .013). After adjusting for multiple comparisons, no differences in outcomes were noted.CONCLUSIONSHispanic patients participating in SWOG trials who received uniform treatment and follow‐up were found to have similar survival outcomes compared with non‐Hispanic patients, with the single exception of those patients with advanced stage prostate cancer. The results of the current study demonstrate that Hispanic patients receiving uniform treatment and follow‐up have similar outcomes compared with non‐Hispanics. Cancer 2018;124:1760‐9. © 2018 American Cancer Society
Temporal trends in the risk of second primary cancers among survivors of adult‐onset cancers, 1980 through 2013: An Australian population‐based study
Authors: Ye Yuanzi , Otahal Petr , Wills Karen E. , Neil Amanda L. , Venn Alison J. 
Published: January 2018

BACKGROUNDThe authors' systematic review indicated an increasing trend in the risk of second primary cancers (SPCs) from the 1980s to 2000 when considering studies from the United States and Australia. It is uncertain whether this trend has continued to increase since 2000.METHODSThe current study was a population‐based study of 51,802 individuals with adult‐onset cancers identified in the Tasmanian Cancer Registry. Patients with a first cancer diagnosis made between 1980 and 2009 were followed up to December 2013. SPC risks were quantified using standardized incidence ratios (SIRs) and absolute excess risks (AERs). Trends in SPC risk were assessed using multivariable Poisson models.RESULTSWith a median follow‐up of 4.8 years (mean, 6.9 years), a total of 5339 SPCs were observed. The SIRs for any SPC increased from 0.98 (95% confidence interval, 0.90‐1.07) after a first cancer diagnosis in 1980 through 1984 to 1.12 (95% confidence interval, 1.05‐1.20) in 2005 through 2009. In multivariable Poisson models accounting for patient sex, age at the time of the first cancer diagnosis, follow‐up interval, and first cancer type, the trend in SIRs increased significantly from 1980 through 2009 for all SPCs (P for trend <.001) and for specific SPCs of the head and neck, lung, digestive tract, and prostate (all P for trend <.05). From 2000 onward, the AER for specific SPCs after specific first cancers was highest for prostate cancer after first cancers of the urinary tract (AER, 54.3 per 10,000 person‐years).CONCLUSIONSIn Tasmania, the risk of SPCs among survivors of adult‐onset cancers has increased with periods of first cancer diagnosis from 1980 through 2009. Increased cancer screening and improved medical imaging may have contributed to the greater risk in recent years. Cancer 2018;124:1808‐18. © 2018 American Cancer Society
Large‐Scale Behavior of Three‐Dimensional Continuous Phase Coexistence Models
Authors: Hairer Martin , Xu Weijun 
Published: January 2018

AbstractWe study a class of three‐dimensional continuous phase coexistence models, and show that, under different symmetry assumptions on the potential, the large‐scale behavior of such models near a bifurcation point is described by the dynamical models for p ∊ {2,3,4}. This result is specific to space dimension 3 and does not hold in dimension 2. © 2018 Wiley Periodicals, Inc.
A general framework for big data knowledge discovery and integration
Authors: Wang Xinyang , Qi Deyu , Lin Weiwei , Yu MinCong , Zheng Zhishuo , Zhou Naqin , Chen Pengguang 
Published: January 2018

SummaryData structure description, conceptual modeling, and logic reasoning for knowledge discovery are three critical factors for the integration of information with heterogeneity. In particular, technologies of NoSQL databases and Internet of Things raise an urgent requirement for a uniform expression of heterogeneous data, and little attention has been paid to researches on the integration of NoSQL databases with traditional data models, as well as the semantic description of big data. To tackle these problems, in this paper, a concept‐and‐relation‐oriented grid data model called GODM model is first proposed based on the definitions of Monad, Compounder, Relation, etc. Then, the GODM model is utilized to uniformly describe traditional data models and NoSQL data models, which eliminates structure differences of heterogeneous data. Next, based on the GODM relation mechanism, an extendable semantic system is built up by choosing SHOIQ(D) description logic as the example to establish the correspondence with GODM grammar subset, providing a fundamental support for semantic integration and knowledge discovery of heterogeneous data. After that, comprehensive comparisons with GODM and other models are made, especially the distinctions between GODM and OWL on the aspects of relation mechanism, hybrid schema, description logic, grammatical constructors, etc. Besides, experimental evaluations and analyses on time and space efficiencies of some primary common data models are conducted after the proposal of a general evaluation model, with the results showing that the GODM model has great advantage on properties of expressiveness, flexibility, etc, particularly time and space efficiency. In summary, the GODM model describes heterogeneous data from both aspects of data structure and semantic relationship and realizes a hybrid schema reconciling the schemaful and schemaless data models, making it especially suitable for dynamic data integration and knowledge discovery from big data models.
Functional trade‐offs and the phylogenetic dispersion of seed traits in a biodiversity hotspot of the Mountains of Southwest China
Authors: Chen Kai , Burgess Kevin S. , Yang Xiang‐Yun , Luo Ya‐Huang , Gao Lian‐Ming , Li De‐Zhu 
Published: January 2018

AbstractThe diversity of traits associated with plant regeneration is often shaped by functional trade‐offs where plants typically do not excel at every function because resources allocated to one function cannot be allocated to another. By analyzing correlations among seed traits, empirical studies have shown that there is a trade‐off between seedling development and the occupation of new habitats, although only a small range of taxa have been tested; whether such trade‐off exists in a biodiverse and complex landscape remains unclear. Here, we amassed seed trait data of 1,119 species from a biodiversity hotspot of the Mountains of Southwest China and analyzed the relationship between seed mass and the number of seeds and between seed mass and time to germination. Our results showed that seed mass was negatively correlated with seed number but positively correlated with time to germination. The same trend was found regardless of variation in life‐form and phylogenetic conservatism. Furthermore, the relation between seed mass and other seed traits was randomly dispersed across the phylogeny at both the order and family levels. Collectively, results suggest that there is a functional trade‐off between seedling development and new habitat occupation for seed plants in this region. Larger seeds tend to produce fewer seedlings but with greater fitness compared to those produced by smaller seeds, whereas smaller seeds tend to have a larger number of seeds that germinate faster compared to large‐seeded species. Apart from genetic constraints, species that produce large seeds will succeed in sites where resource availability is low, whereas species with high colonization ability (those that produce a high number of seeds per fruit) will succeed in new niches. This study provides a mechanistic explanation for the relatively high levels of plant diversity currently found in a heterogeneous region of the Mountains of Southwest China.
Differences among six woody perennials native to Northern Europe in their level of genetic differentiation and adaptive potential at fine local scale
Authors: Lobo Albin , Hansen Jon Kehlet , Hansen Lars Nørgaard , Dahl Kjær Erik 
Published: January 2018

AbstractThe ability of perennial species to adapt their phenology to present and future temperature conditions is important for their ability to retain high fitness compared to other competing plant species, pests, and pathogens. Many transplanting studies with forest tree species have previously reported substantial genetic differentiation among populations within their native range. However, the question of “how local is local” is still highly debated in conservation biology because studies on genetic patterns of variation within and among populations at the local scale are limited and scattered. In this study, we compare the level of genetic differentiation among populations of six different perennial plant species based on their variation in spring flushing. We assess the level of additive genetic variation present within the local population. For all six species, we find significant differentiation among populations from sites with mean annual temperature ranging between 7.4°C and 8.4°C. The observed variation can only be partly explained by the climate at the site of origin. Most clear relationship between early flushing and higher average spring temperature is observed for the three wind‐pollinated species in the study, while the relations are much less clear for the three insect‐pollinated species. This supports that pollination system can influence the balance between genetic drift and natural selection and thereby influence the level of local adaptation in long‐lived species. On the positive side, we find that the native populations of woody plant species have maintained high levels of additive genetic variation in spring phenology, although this also differs substantially among the six studied species.
Wrong, but useful: regional species distribution models may not be improved by range‐wide data under biased sampling
Authors: El‐Gabbas Ahmed , Dormann Carsten F. 
Published: January 2018

AbstractSpecies distribution modeling (SDM) is an essential method in ecology and conservation. SDMs are often calibrated within one country's borders, typically along a limited environmental gradient with biased and incomplete data, making the quality of these models questionable. In this study, we evaluated how adequate are national presence‐only data for calibrating regional SDMs. We trained SDMs for Egyptian bat species at two different scales: only within Egypt and at a species‐specific global extent. We used two modeling algorithms: Maxent and elastic net, both under the point‐process modeling framework. For each modeling algorithm, we measured the congruence of the predictions of global and regional models for Egypt, assuming that the lower the congruence, the lower the appropriateness of the Egyptian dataset to describe the species' niche. We inspected the effect of incorporating predictions from global models as additional predictor (“prior”) to regional models, and quantified the improvement in terms of AUC and the congruence between regional models run with and without priors. Moreover, we analyzed predictive performance improvements after correction for sampling bias at both scales. On average, predictions from global and regional models in Egypt only weakly concur. Collectively, the use of priors did not lead to much improvement: similar AUC and high congruence between regional models calibrated with and without priors. Correction for sampling bias led to higher model performance, whatever prior used, making the use of priors less pronounced. Under biased and incomplete sampling, the use of global bats data did not improve regional model performance. Without enough bias‐free regional data, we cannot objectively identify the actual improvement of regional models after incorporating information from the global niche. However, we still believe in great potential for global model predictions to guide future surveys and improve regional sampling in data‐poor regions.
Single‐nucleotide polymorphism discovery and panel characterization in the African forest elephant
Authors: Bourgeois Stéphanie , Senn Helen , Kaden Jenny , Taggart John B. , Ogden Rob , Jeffery Kathryn J. , Bunnefeld Nils , Abernethy Katharine , McEwing Ross 
Published: January 2018

AbstractThe continuing decline in forest elephant (Loxodonta cyclotis) numbers due to poaching and habitat reduction is driving the search for new tools to inform management and conservation. For dense rainforest species, basic ecological data on populations and threats can be challenging and expensive to collect, impeding conservation action in the field. As such, genetic monitoring is being increasingly implemented to complement or replace more burdensome field techniques. Single‐nucleotide polymorphisms (SNPs) are particularly cost‐effective and informative markers that can be used for a range of practical applications, including population census, assessment of human impact on social and genetic structure, and investigation of the illegal wildlife trade. SNP resources for elephants are scarce, but next‐generation sequencing provides the opportunity for rapid, inexpensive generation of SNP markers in nonmodel species. Here, we sourced forest elephant DNA from 23 samples collected from 10 locations within Gabon, Central Africa, and applied double‐digest restriction‐site‐associated DNA (ddRAD) sequencing to discover 31,851 tags containing SNPs that were reduced to a set of 1,365 high‐quality candidate SNP markers. A subset of 115 candidate SNPs was then selected for assay design and validation using 56 additional samples. Genotyping resulted in a high conversion rate (93%) and a low per allele error rate (0.07%). This study provides the first panel of 107 validated SNP markers for forest elephants. This resource presents great potential for new genetic tools to produce reliable data and underpin a step‐change in conservation policies for this elusive species.