bluuebunny/crossref_metadata_2025_split huggingface dataset:
Benzo‐Annulated Steroids: Synthesis of Octahydro‐indeno‐phenanthrenes by Formal [3+3] Cyclocondensation Reaction with 1,3‐Bis[(trimethylsilyl)oxy]buta‐1,3‐dienes
Authors: Erben Friedrich , Specowius Verena , Wölfling János , Schneider Gyula , Langer Peter 
Published: May 2013

AbstractOctahydro‐indeno‐phenanthrenes, benzo‐annulated steroids, were prepared by formal [3+3] cyclocondensation reaction of 1,3‐bis[(trimethylsilyl)oxy]buta‐1,3‐dienes with the silyl enol ether of 16‐formylestrone methyl ether.
Five New Steroidal Alkaloid Glycosides from Solanum tuberosum
Authors: Zhang Zhi‐Qiang , Luo Jian‐Guang , Wang Jun‐Song , Kong Ling‐Yi 
Published: May 2013

AbstractFive new steroidal alkaloid glycosides, 1–5, along with the known analog 6, have been isolated from the aerial parts of Solanum tuberosum. The structures of the new compounds were elucidated by spectroscopic methods, including 1D‐ and 2D‐NMR and HR‐ESI‐MS techniques, as well as by comparison of the spectral data with those of related compounds. Only compound 6 showed significant cytotoxicity.
Scope and Limitations of the Base‐Free Copper(I) Oxide Catalyzed N‐Heteroarylation of 1H‐(Benz)imidazoles with B‐Heteroarylboronic Acids or 2‐Heteroaryl‐4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolanes
Authors: Begouin Agathe , Queiroz Maria‐João R. P. 
Published: May 2013

AbstractThe known, very efficient base‐free copper(I) oxide catalyzed N‐arylation reaction performed in MeOH at room temperature for the synthesis of N‐substituted azoles and amines was extended to the heterocyclic series, i.e., we report herein the base‐free copper(I) oxide catalyzed N‐heteroarylation of 1H‐(benz)imidazole, by means of electron‐rich or electron‐deficient B‐heteroarylboronic acids or 2‐heteroaryl‐4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolanes (Schemes 1 and 2). Under these conditions, N‐heteroarylated 1H‐(benz)imidazoles were obtained in good to excellent yields (Tables 1 and 2). This is the first time that 2‐heteroaryl‐4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolanes were used in this type of reaction.
Stereoselective Synthesis of (−)‐Pinidinone
Authors: Shankaraiah Gundeti , Vijaya Kumar Tiruvayamudi , Venkateswara Reddy Guvvala , Madhusudana Rao Janaswamy , Suresh Babu Katragadda 
Published: May 2013

AbstractA simple and efficient stereoselective linear approach to the total synthesis of (−)‐pinidinone has been accomplished starting from propane‐1,3‐diol, and employing Maruoka asymmetric allylation and Grubbs' olefin cross‐metathesis as the key steps.
Synthesis of Thymidine, Uridine, and 5‐Methyluridine Nucleolipids: Tools for a Tuned Lipophilization of Oligonucleotides
Authors: Werz Emma , Viere Rebecca , Gassmann Gina , Korneev Sergei , Malecki Edith , Rosemeyer Helmut 
Published: May 2013

AbstractThree pyrimidine nucleosides, uridine (1), 5‐methyluridine (6), and 2′‐deoxythymidine (11), were converted to amphiphilic nucleolipids. Compounds 1 and 6 were lipophilized by introduction of symmetric ketal moieties with various carbon chain lengths (i.e., 5–17). Two ketal derivatives, 2b and 7a, were additionally further hydrophobized by N(3)‐farnesylation. 2′‐Deoxythymidine was alkylated at N(3) with a cetyl (=hexadecyl) residue, either directly or, after complete orthogonal protection of the sugar OH groups, by Mitsunobu reaction with hexadecan‐1‐ol. Some of the nucleolipids were subsequently converted to their 2‐cyanoethyl phosphoramidites (5′ or 3′), one of which was used for an exemplary synthesis of a lipo‐oligonucleotide. The sequence of this lipo‐oligonucleotide is an encoded manifestation of Pythagoras' law, created with a key table in which the letters of the alphabet, the numbers from 0 to 9 as well as the mostly used mathematical symbols are allocated to a ribonucleic acid triplet of the genetic code.
Stoichiometric Reactions of Enamines Derived from Diphenylprolinol Silyl Ethers with Nitro Olefins and Lessons for the Corresponding Organocatalytic Conversions – a Survey
Authors: Seebach Dieter , Sun Xiaoyu , Ebert Marc‐Olivier , Schweizer W. Bernd , Purkayastha Nirupam , Beck Albert K. , Duschmalé Jörg , Wennemers Helma , Mukaiyama Takasuke , Benohoud Meryem , Hayashi Yujiro , Reiher Markus 
Published: May 2013

AbstractThe stoichiometric reactions of enamines prepared from aldehydes and diphenyl‐prolinol silyl ethers (intermediates of numerous organocatalytic processes) with nitro olefins have been investigated. As reported in the last century for simple achiral and chiral enamines, the products are cyclobutanes (4 with monosubstituted nitro‐ethenes), dihydro‐oxazine N‐oxide derivatives (5 with disubstituted nitro‐ethenes), and nitro enamines derived from γ‐nitro aldehydes (6, often formed after longer reaction times). The same types of products were shown to be formed, when the reactions were carried out with peptides H‐Pro‐Pro‐Xaa‐OMe that lack an acidic H‐atom. Functionalized components such as alkoxy enamines, nitro‐acrylates, acetamido‐nitro‐ethylene, or hydroxylated nitro olefins also form products carrying the diphenyl‐prolinol silyl ether as a substituent. All of these products must be considered intermediates in the corresponding catalytic reactions; the investigation of their chemical properties provided useful hints about the rates, the conditions, the catalyst resting states or irreversible traps, and/or the limitations of the corresponding organocatalytic processes. High‐level DFT and MP2 computations of the structures of alkoxy enamines and thermodynamic data of a cyclobutane dissociation are also described. Some results obtained with the stoichiometrically prepared intermediates are not compatible with previous mechanistic proposals and assumptions.
Discussion about the validity of sharp‐interface models to deal with seawater intrusion in coastal aquifers
Authors: Llopis‐Albert Carlos , Pulido‐Velazquez David 
Published: May 2013

AbstractAnalytical models have been exhaustively used to study simple seawater intrusion problems and the sustainable management of groundwater resources in coastal aquifers because of its simplicity, easy implementation, and low computational cost. Most of these models are based on the sharp‐interface approximation and the Ghyben–Herzberg relation, and their governing equations are expressed in terms of a single potential theory to calculate critical pumping rates in a coastal pumping scenario. The Ghyben–Herzberg approach neglects mixing of fresh water and seawater and implicitly assumes that salt water remains static. Therefore, the results of the analytical solutions may be inaccurate and unacceptable for some real‐complex case studies. This paper provides insight into the validity of sharp‐interface models to deal with seawater intrusion in coastal aquifers, i.e. when they can be applied to obtain accurate enough results. For that purpose, this work compares sharp‐interface solutions, based on the Ghyben–Herzberg approach, with numerical three‐dimensional variable‐density flow simulations for a set of heterogeneous groundwater flow and mass transport parameters, and different scenarios of spatially distributed recharge values and spatial wells placement. The numerical experiment has been carried out in a 3D unconfined synthetic aquifer using the finite difference numerical code SEAWAT for solving the coupled partial differential equations of flow and density‐dependent transport. This paper finds under which situations the sharp‐interface solution gives good predictions in terms of seawater penetration, transition zone width and critical pumping rates. Additionally, the simulation runs indicate to which parameters and scenarios the results are more sensitive. Copyright © 2013 John Wiley & Sons, Ltd.
Modelling how vegetation cover affects climate change impacts on streamflow timing and magnitude in the snowmelt‐dominated upper Tuolumne Basin, Sierra Nevada
Authors: Cristea Nicoleta C. , Lundquist Jessica D. , Loheide Steven P. , Lowry Christopher S. , Moore Courtney E. 
Published: May 2013

AbstractWe investigated, through hydrologic modelling, the impact of the extent and density of canopy cover on streamflow timing and on the magnitude of peak and late summer flows in the upper Tuolumne basin (2600–4000 m) of the Sierra Nevada, California, under current and warmer temperatures. We used the Distributed Hydrology Soil Vegetation Model for the hydrologic modelling of the basin, assuming four vegetation scenarios: current forest (partial cover, 80% density), all forest (uniform coverage, 80% density), all barren (no forest) and thinned forest (partial cover, 40% density) for a medium‐high emissions scenario causing a 3.9 °C warming over a 100‐year period (2001–2100). Significant advances in streamflow timing, quantified as the centre of mass (COM) of over 1 month were projected for all vegetation scenarios. However, the COM advances faster with increased forest coverage. For example, when forest covered the entire area, the COM occurred on average 12 days earlier compared with the current forest coverage, with the rate of advance higher by about 0.06 days year−1 over 100 years and with peak and late summer flows lower by about 20% and 27%, respectively. Examination of modelled changes in energy balance components at forested and barren sites as temperatures rise indicated that increases in net longwave radiation are higher in the forest case and have a higher contribution to melting earlier in the calendar year when shortwave radiation is a smaller fraction of the energy budget. These increases contributed to increased midwinter melt under the forest at temperatures above freezing, causing decreases in total accumulation and higher winter and early spring melt rates. These results highlight the importance of carefully considering the combined impacts of changing forest cover and climate on downstream water supply and mountain ecosystems. Copyright © 2013 John Wiley & Sons, Ltd.
Modelling potential effects of climate change on winter turbidity loading in the Ashokan Reservoir, NY
Authors: Samal Nihar R. , Matonse Adao. H. , Mukundan Rajith , Zion Mark S. , Pierson Donald C. , Gelda Rakesh K. , Schneiderman Elliot M. 
Published: May 2013

AbstractRecent studies have indicated that potential future climate change may lead to changes in the timing and quantity of snowpack accumulation and winter (November to April) streamflow patterns including increased streamflow and turbidity in early winter and a slight reduction in turbidity loads at the time of traditional early spring run‐off. In this study, we examine the potential effects of these predicted changes on reservoir turbidity levels. Our analysis focuses on Ashokan Reservoir, NY, which can at times receive significant watershed turbidity inputs mainly from stream channel erosion from the Esopus Creek. Both measured and simulated turbidity loads and climatology are input to CE‐QUAL‐W2 (W2), a reservoir turbidity transport model that can simulate reservoir turbidity and other water quality parameters. The W2 model is applied to estimate the effects of hydroclimatology on effective settling rates and turbidity transport as a result of differences in reservoir thermal structure during summer and winter events. Simulations suggest that the effective settling velocity is substantially lower at low temperatures during winter time. Winter average stream flow is simulated to increase by 12% and 20%, which leads to increases in reservoir turbidity by 11% and 17% for the future period 2046–2065 and 2081–2100, respectively. From a seasonal perspective, a change in timing of peak streamflow with increased flows during the winter and slightly reduced flows during early spring leads to increased average reservoir turbidity during winter and slightly decreased in‐reservoir turbidity during early spring and summer. Copyright © 2013 John Wiley & Sons, Ltd.
On the Origin of the Canonical Nucleobases: An Assessment of Selection Pressures across Chemical and Early Biological Evolution
Authors: Rios Andro C. , Tor Yitzhak 
Published: May 2013

AbstractThe native bases of RNA and DNA are prominent examples of the narrow selection of organic molecules upon which life is based. How did nature “decide” upon these specific heterocycles? Evidence suggests that many types of heterocycles could have been present on the early Earth. It is therefore likely that the contemporary composition of nucleobases is a result of multiple selection pressures that operated during early chemical and biological evolution. The persistence of the fittest heterocycles in the prebiotic environment towards, for example, hydrolytic and photochemical assaults, may have given some nucleobases a selective advantage for incorporation into the first informational polymers. The prebiotic formation of polymeric nucleic acids employing the native bases remains, however, a challenging problem to reconcile. Hypotheses have proposed that the emerging RNA world may have included many types of nucleobases. This is supported by the extensive utilization of non‐canonical nucleobases in extant RNA and the resemblance of many of the modified bases to heterocycles generated in simulated prebiotic chemistry experiments. Selection pressures in the RNA world could have therefore narrowed the composition of the nucleic acid bases. Two such selection pressures may have been related to genetic fidelity and duplex stability. Considering these possible selection criteria, the native bases along with other related heterocycles seem to exhibit a certain level of fitness. We end by discussing the strength of the N‐glycosidic bond as a potential fitness parameter in the early DNA world, which may have played a part in the refinement of the alphabetic bases.
Institutional Research in Light of Internationalization, Growth, and Competition
Authors: Taylor Barrett J. , Webber Karen L. , Jacobs Gerrie J. 
Published: May 2013

AbstractGlobalization, growth, and competition are challenges faced by many postsecondary institutions across the world. Institutional researchers have a prominent role to play in examining the issues related to these challenges and alerting campus leaders to the impact they may have on the institution and higher education in general.
Institutional Research in Emerging Countries of Southern Africa, Latin America, and the Middle East and North Africa: Global Frameworks and Local Practices
Authors: Lange Lis , Saavedra F. Mauricio , Romano Jeanine 
Published: May 2013

AbstractThis chapter presents a synthesis of the conceptualization and practice of institutional research (IR) in higher education (HE) in emerging countries across Southern Africa, Latin America and the Middle East and North Africa (MENA) regions. The chapter contextualizes the growing need for IR in these regions, identifies problems and challenges related to the implementation of IR at system and institutional levels, and offers some reflections about the future of IR in these regions. The chapter argues that the homogenizing effect of globalization makes IR practices very much alike across regions.
Challenges in Developing Data Collection Systems in a Rapidly Evolving Higher Education Environment
Authors: Borden Victor M. H. , Calderon Angel , Fourie Neels , Lepori Benedetto , Bonaccorsi Andrea 
Published: May 2013

AbstractEfforts to develop common higher education data standards are expanding both within and across countries. The institutional research (IR) community plays a critical role in assuring that these efforts capture the diverse manifestations of the postsecondary and tertiary education systems and promote responsible comparisons.
The need for stent–lesion matching to optimize outcomes of intracoronary stent implantation
Authors: Lanzer Peter , Strupp Gerhard , Schmidt Wolfram , Topoleski L. D. Timmie 
Published: May 2013

AbstractIntracoronary stents have markedly improved the outcomes of catheter‐based coronary interventions. Intracoronary stent implantation rates of over 90% during coronary angioplasty are common. Stent implantations are associated with a small but statistically significant number of adverse outcomes including restenosis, thrombosis, strut malapposition, incomplete strut endothelialization, and various types of stenting failure. Better matching of biomechanical properties of stents and lesions could further improve the clinical outcome of intracoronary stenting. Thus, in this article, we assess the need for advanced intracoronary stent–lesion matching. We reviewed the data on biomechanics of coronary stents and lesions to develop knowledge‐based rationale for optimum intracoronary stent selection. The available technical information on marketed intracoronary stents and the current understanding of the biomechanical properties of coronary lesions at rest and under stress are limited, preventing the development of knowledge‐based rationale for optimum intracoronary stent selection at present. Development of knowledge‐based selection of intracoronary stents requires standardization of mechanical stent testing, communication of the nonproprietary technical data on stents by the industry and dedicated research into procedural stent–lesion interactions. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 101B: 1560–1570, 2013.
Higher doses of CD34+ progenitors are associated with improved overall survival without increasing GVHD in reduced intensity conditioning allogeneic transplant recipients with clinically advanced disease
Authors: Gómez‐Almaguer David , Gómez‐Peña Álvaro , Jaime‐Pérez José Carlos , Gómez‐Guijosa Miguel Ángel , Cantú‐Rodríguez Olga , Gutiérrez‐Aguirre Homero , Martínez‐Cabriales Sylvia Aidé , García‐Rodríguez Fernando , Olguín‐Ramírez Leticia A. , Salazar‐Riojas Rosario , Méndez‐Ramírez Nereida 
Published: May 2013

ObjectiveThe influence of CD34+ cell dose on the outcome of allogeneic peripheral blood stem cell (PBSC) transplantation after reduced intensity conditioning (RIC) remains controversial. The impact of the number of CD34+ hematoprogenitors infused on transplant outcome and on the incidence of graft versus host disease (GVHD) was analyzed.Materials and methodsData of 138 patients with advanced hematological diseases who received an allogeneic PBSC transplant after RIC were analyzed. Donors were mobilized with granulocyte colony‐stimulating factor and underwent one to three apheresis procedures. Incidence of acute and chronic GVHD and overall and event‐free survival (OS and EFS) was determined.ResultsThe median number of CD34+ cells infused was 5.57 × 106 kg−1 (range: 1.1–15.6). There was no relationship between CD34+ cell dose and neutrophil or platelet engraftment. Patients receiving ≥5 × 106 kg−1 CD34+ cells had a 63.1% 5‐year OS when compared with 48.2% for those receiving a lower number (P = 0.024). At 5‐year follow‐up, there was no significant difference in EFS between the groups (44% vs. 42.8%, P = 0.426). No relationship between CD34+ cell dose and acute GVHD was found (P = 0.1). Relapse rate was the same in patients with and without acute GVHD (P = 0.117). A nonsignificant improvement on OS and EFS in patients who developed chronic GVHD was found (P = 0.57 and 0.41).ConclusionA CD34+ cell dose ≥5 × 106 kg−1 was associated with a significantly higher OS, but no improved EFS in high‐risk patients. The number of CD34+ progenitors infused had no influence on the incidence of acute or chronic GVHD. J. Clin. Apheresis 28:349–355, 2013. © 2013 Wiley Periodicals, Inc.
Angiotensin Receptor Blockers and Risk of Prostate Cancer Among United States Veterans
Authors: Rao Gowtham A. , Mann Joshua R. , Bottai Matteo , Uemura Hiroji , Burch James B. , Bennett Charles Lee , Haddock Kathlyn Sue , Hébert James R. 
Published: May 2013

AbstractTo address concerns regarding increased risk of prostate cancer (PrCA) among angiotensin receptor blocker (ARB) users, we used national retrospective data from the Department of Veterans Affairs (VA) through the Veterans Affairs Informatics and Computing Infrastructure. We identified a total of 543,824 unique Veterans who were classified into either ARB treated or not‐treated in 1:15 ratio. The two groups were balanced using inverse probability of treatment weights. A double‐robust cox‐proportional hazards model was used to estimate the hazard ratio for PrCA incidence. To evaluate for a potential Gleason score stage migration, we conducted weighted Cochrane‐Armitage test. Post weighting, the rates of PrCA in treated and not‐treated groups were 506 (1.5%) and 8,269 (1.6%), respectively; representing a hazard ratio of (0.91, p‐value .049). There was no significant difference in Gleason scores between the two groups. We found a small, but statistically significant, reduction in the incidence of clinically detected PrCA among patients assigned to receive ARB with no countervailing effect on degree of differentiation (as indicated by Gleason score). Findings from this study support Food and Drug Administration's recent conclusion that ARB use does not increase risk of incident PrCA.
Boreal winter low‐frequency variability in CMIP5 models
Authors: Lee Yun‐Young , Black Robert X. 
Published: May 2013

AbstractThis study assesses the capability of CMIP5 models in representing primary modes of boreal winter extratropical low‐frequency variability. Rotated principal component analysis is applied to monthly mean output from historical simulations of 14 plus two variants models and National Centers for Environmental Prediction–National Center for Atmospheric Research reanalyses (NNR) to isolate the leading patterns of variability in 500 hPa height. For each model data set, North Atlantic Oscillation (NAO)‐like and Pacific‐North American (PNA)‐like patterns are identified using pattern correlation analysis (against NNR patterns). The relative pattern correspondence among CMIP5 models and reanalyses is further quantified via cluster analyses of the rotated empirical orthogonal function, NAO‐like, and PNA‐like patterns, respectively. For both NAO and PNA, 18.8% of the model patterns lie within the same cluster as NNR. Composite structural differences among clusters chiefly consist of (a) spatial displacements of or (b) regional magnitude disparities in the primary anomaly features. While all models replicate the basic aspects of PNA, a small minority of models fails to replicate NAO pattern. Overall, the best performing model is the “GFDL‐ESM2G.” Interestingly, models having a well‐resolved stratosphere generally perform more poorly than those without. Model biases in low‐frequency mode structure have important consequences for the representation of associated regional anomalies in surface air temperature and storm track behavior. Those differences among clusters are linked to variations in dynamical structures and their relation to the climatological‐mean flow. It is concluded that some state‐of‐the‐art models have important deficiencies in representing low‐frequency variability and some of these deficiencies are associated with the failure of models to adequately replicate the observed climatological stationary waves.