bluuebunny/crossref_metadata_2025_split huggingface dataset:
Surgical delay is a critical determinant of survival in perforated peptic ulcer
Authors: Buck D L , Vester-Andersen M , Møller M H 
Published: June 2013

Abstract

Background
Morbidity and mortality following perforated peptic ulcer (PPU) remain substantial. Surgical delay is a well established negative prognostic factor, but evidence derives from studies with a high risk of bias. The aim of the present nationwide cohort study was to evaluate the adjusted effect of hourly surgical delay on survival after PPU.

Methods
This was a cohort study including all Danish patients treated surgically for PPU between 1 February 2003 and 31 August 2009. Medically treated patients and those with a malignant ulcer were excluded. The associations between surgical delay and 30-day survival are presented as crude and adjusted relative risks (RRs) with 95 per cent confidence intervals (c.i.).

Results
A total of 2668 patients were included. Their median age was 70·9 (range 16·2–104·2) years and 55·4 per cent (1478 of 2668) were female. Some 67·5 per cent of the patients (1800 of 2668) had at least one of six co-morbid diseases and 45·6 per cent had an American Society of Anesthesiologists fitness grade of III or more. A total of 708 patients (26·5 per cent) died within 30 days of surgery. Every hour of delay from admission to surgery was associated with an adjusted 2·4 per cent decreased probability of survival compared with the previous hour (adjusted RR 1·024, 95 per cent c.i. 1·011 to 1·037).

Conclusion
Limiting surgical delay in patients with PPU seems of paramount importance.
Raised haematocrit concentration and the risk of death and vascular complications after major surgery
Authors: Musallam K M , Porter J B , Sfeir P M , Tamim H M , Richards T , Lotta L A , Peyvandi F , Jamali F R 
Published: June 2013

Abstract

Background
Preoperative anaemia is associated with adverse postoperative outcomes. Data on raised preoperative haematocrit concentration are limited. This study aimed to evaluate the effect of raised haematocrit on 30-day postoperative mortality and vascular events in patients undergoing major surgery.

Methods
This was a cohort study using the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database. Thirty-day mortality and vascular events, demographics and perioperative risk factors were obtained for adults undergoing major surgery. The adjusted effect of raised (over 0·50) compared with normal (0·41–0·50, American Medical Association reference range) preoperative haematocrit concentration on postoperative outcomes was assessed. Separate sex-specific analyses were also conducted, using haematocrit concentration thresholds commonly used in the diagnosis and management of apparent or absolute erythrocytosis.

Results
Some 3961 (2·0 per cent) of 197 469 patients had a raised haematocrit concentration before surgery. After adjustment, the 30-day postoperative mortality rate was higher in patients with raised haematocrit than in those without (odds ratio (OR) 2·23, 95 per cent confidence interval 1·77 to 2·80). Thirty-day rates of deep vein thrombosis (OR 1·95, 1·44 to 2·64) and pulmonary embolism (OR 1·79, 1·17 to 2·73), but not myocardial infarction or stroke, were also higher in patients with a raised haematocrit concentration. The effect on mortality was noted beyond the haematocrit thresholds of 0·48 in women and 0·52 in men; the effect estimates were considerably higher for values exceeding 0·54. Values between 0·41 and 0·45 were not associated with increased mortality risk. Similar observations were noted for venous thrombosis, although with apparent sex differences.

Conclusion
A raised haematocrit concentration was associated with an increased risk of 30-day mortality and venous thrombosis following major surgery.
PTEN expression is consistent in colorectal cancer primaries and metastases and associates with patient survival
Authors: Atreya Chloe E. , Sangale Zaina , Xu Nafei , Matli Mary R. , Tikishvili Eliso , Welbourn William , Stone Steven , Shokat Kevan M. , Warren Robert S. 
Published: June 2013

AbstractPhosphatase and tensin homologue deleted on chromosome 10 (PTEN) negatively regulates the phosphoinositide‐3‐kinase (PI3K) signaling pathway. In colorectal cancer (CRC), observed frequencies of loss of PTEN expression, concordant expression in primary tumors and metastases, and the association of PTEN status with outcome vary markedly by detection method. We determined the degree to which PTEN expression is consistent in 70 matched human CRC primaries and liver metastases using a validated immunohistochemistry assay. We found loss of PTEN expression in 12.3% of assessable CRC primaries and 10.3% of assessable liver metastases. PTEN expression (positive or negative) was concordant in 98% of matched colorectal primaries and liver metastases. Next we related PTEN status to mutations in RAS and PI3K pathway genes (KRAS, NRAS, BRAF, and PIK3CA) and to overall survival (OS). PTEN expression was not significantly associated with the presence or absence of mutations in RAS or PI3K pathway genes. The median OS of patients whose tumors did not express PTEN was 9 months, compared to 49 months for patients whose tumors did express PTEN (HR = 6.25, 95% confidence intervals (CI) (1.98, 15.42), P = 0.0017). The association of absent PTEN expression with increased risk of death remained significant in multivariate analysis (HR = 6.31, 95% CI (2.03, 17.93), P = 0.0023). In summary, PTEN expression was consistent in matched CRC primaries and in liver metastases. Therefore, future investigations of PTEN in metastatic CRC can use primary tumor tissue. In patients with liver‐only metastases, loss of PTEN expression predicted poor OS.
Chain Growth by CO Insertion in the Fischer–Tropsch Reaction
Authors: van Santen Rutger A. , Markvoort Albert J. 
Published: June 2013

AbstractThe molecular kinetics of the mechanism of chain growth through CO insertion of the Fischer–Tropsch reaction is analyzed. The maximum chain growth within the CO insertion chain growth model is predicted if the rate of CO activation to give the C1 species that initiates chain growth balances the rate of chain growth termination. The overall rate of chain growth, determined by the elementary rates of CO insertion, hydrogen‐transfer reaction steps, and CO bond cleavage, has to be fast compared to the rate of methanation and the rate of chain growth termination, which gives an oxygenate or hydrocarbon product. However, estimates of rate constants based on quantum‐chemical data predict low chain growth within this CO insertion mechanism, which is mainly caused by the relatively slow rate of CO insertion into the growing chain compared to the rate of product desorption. Such a high barrier for CO insertion is consistent with oxygenate formation through the carbide mechanism pathway. A comparison of the derived expressions for CO consumption shows that the rate of chain growth is limiting within the mechanism of chain growth through CO insertion, whereas within the carbide mechanism it is rate controlled by the rate of CO to CHx monomer formation.
Hydrogen Transfer Processes Mediated by Supported Iridium Oxide Nanoparticles
Authors: Hammond Ceri , Schümperli Martin T. , Conrad Sabrina , Hermans Ive 
Published: June 2013

AbstractHomogeneous iridium catalysts have demonstrated exceptional catalytic activity for a number of hydrogen transfer reactions. Herein, we demonstrate the synthesis of a heterogeneous iridium catalyst supported on nanoparticulate cerium oxide and investigate its application for the aerobic oxidation of benzyl alcohol and the Meerwein–Ponndorf–Verley transfer hydrogenation of cyclohexanone. Along with the optimisation of the activity of the catalyst, the kinetic parameters have been examined to unravel the elementary reaction steps mediated by this catalyst and further rationalise the observed structure–activity relationships. Both spectroscopic and catalytic investigations suggest that iridium oxide nanoparticles, most likely Ir2O3, mediate these reactions via the formation of metal hydroxide species, which are subsequently reoxidised with either a molecular oxygen or a ketone. In contrast to many other metal‐ or metal oxide‐based catalysts, this catalyst can perform the selective oxidation of alcohols in the absence of a base, at mild temperatures and at a low metal loading.
Mechanistic Insight into the Staudinger Reaction Catalyzed by N‐Heterocyclic Carbenes
Authors: Hans Morgan , Wouters Johan , Demonceau Albert , Delaude Lionel 
Published: June 2013

AbstractFour zwitterions were prepared by treating 1,3‐dimesitylimidazolin‐2‐ylidene (SIMes) or 1,3‐dimesitylimidazol‐2‐ylidene (IMes) with either N‐tosyl benzaldimine or diphenylketene. They were isolated in high yields and characterized by IR and NMR spectroscopy. The molecular structures of three of them were determined by using X‐ray crystallography and their thermal stability was monitored by using thermogravimetric analysis. The imidazol(in)ium‐2‐amides were rather labile white solids that did not show any tendency to tautomerize into the corresponding 1,2,2‐triaminoethene derivatives. They displayed a mediocre catalytic activity in the Staudinger reaction of N‐tosyl benzaldimine with diphenylketene. In contrast, the imidazol(in)ium‐2‐enolates were orange‐red crystalline materials that remained stable over extended periods of time. Despite their greater stability, these zwitterions turned out to be efficient promoters for the model cycloaddition under scrutiny. As a matter of fact, their catalytic activity matched those recorded with the free carbenes. Altogether, these results provide strong experimental insight into the mechanism of the Staudinger reaction catalyzed by N‐heterocyclic carbenes. They also highlight the superior catalytic activity of the imidazole‐based carbene IMes compared with its saturated analogue SIMes in the reaction under consideration.
Solvent Responsive Magnetic Dynamics of a Dinuclear Dysprosium Single‐Molecule Magnet
Authors: Ren Min , Bao Song‐Song , Hoshino Norihisa , Akutagawa Tomoyuki , Wang Bingwu , Ding Yu‐Chen , Wei Shiqiang , Zheng Li‐Min 
Published: June 2013

AbstractA new dysprosium(III) phosphonate dimer {Dy(notpH4)(NO3)(H2O)}2⋅8 H2O (1) [notpH6=1,4,7‐triazacyclononane‐1,4,7‐triyl‐tris(methylenephosphonic acid)] that contains two equivalent DyIII ions with a three‐capped trigonal prism environment is reported. Complex 1 can be transformed into {Dy(notpH4)(NO3)(H2O)}2 (2) in a reversible manner by desorption and absorption of solvent water at ambient temperature. This process is accompanied by a large dielectric response. Magnetic studies reveal that both 1 and 2 show thermally activated magnetization relaxation as expected for single‐molecule magnets. Moreover, the magnetic dynamics of the two compounds can be manipulated by controlling the number of solvent molecules at room temperature.
A New Dynamic Covalent Bond of SeN: Towards Controlled Self‐Assembly and Disassembly
Authors: Yi Yu , Xu Huaping , Wang Lu , Cao Wei , Zhang Xi 
Published: June 2013

AbstractA new kind of SeN dynamic covalent bond has been found that can form between the Se atom of a phenylselenyl halogen species and the N atom of a pyridine derivative, such as polystyrene‐b‐poly(4‐vinylpyridine). This SeN dynamic covalent bond can be reversibly and rapidly formed or cleaved under acidic or basic conditions, respectively. Furthermore, the bond can be dynamically cleaved by heating or treatment with stronger electron‐donating pyridine derivatives. The multiple responses of SeN bond to external stimuli has enriched the existing family of dynamic covalent bonds. It can be used for controlled and reversible self‐assembly and disassembly, which may find potential applications in a number of areas, including self‐healing materials and responsive assemblies.
Energy, Equipment and Cost Savings by Using a Membrane Unit in an Amine‐Based Absorption Process for CO2 Removal
Authors: Song Shankui , Esche Erik , Stünkel Steffen , Brinkmann Torsten , Wind Jan , Shishatskiy Sergey , Wozny Günter 
Published: June 2013

AbstractA hybrid system consisting of a membrane unit and an amine‐based process for CO2 removal in the oxidative coupling of methane is investigated experimentally and in simulations. Absorption processes with two different absorbents for removing 90 % of CO2 from the feed stream are regarded as benchmarks and compared to the membrane process with respect to potential energy, equipment, and cost reductions. The results show that a membrane unit using polyimide could assist with CO2 capture and lead to a reduction of the consumed energy per kilogram of CO2 by 40 % and also reduce the size of the absorption columns. Alternative processes with a two‐step membrane cascade to enhance the recovery of product ethylene are also discussed.
Computed tomographic colonography for colorectal cancer screening
Authors: Hassan Cesare , Pooler B. Dustin , Kim David H. , Rinaldi Antonio , Repici Alessandro , Pickhardt Perry J. 
Published: June 2013

BACKGROUNDThe objective of this study was to determine whether age, sex, a positive family history of colorectal cancer, and body mass index (BMI) are important predictors of advanced neoplasia in the setting of screening computed tomographic colonography (CTC).METHODSConsecutive patients who were referred for first‐time screening CTC from 2004 to 2011 at a single medical center were enrolled. Results at pathology were recorded for all patients who underwent polypectomy. Logistic regression was used to identify significant predictor variables for advanced neoplasia (any adenoma ≥10 mm or with villous component, high‐grade dysplasia, or adenocarcinoma). Odds ratios (ORs) were used to express associations between the study variables (age, sex, BMI, and a positive family history of colorectal cancer) and advanced neoplasia.RESULTSIn total, 7620 patients underwent CTC screening. Of these, 276 patients (3.6%; 95% confidence interval [CI], 3.2%‐4.1%) ultimately were diagnosed with advanced neoplasia. At multivariate analysis, age (mean OR per 10‐year increase, 1.8; 95% CI, 1.6‐2.0) and being a man (OR, 1.7; 95% CI, 1.3‐2.2) were independent predictors of advanced neoplasia, whereas BMI and a positive family history of colorectal cancer were not. The number needed to screen to detect 1 case of advanced neoplasia varied from 51 among women aged ≤55 years to 10 among men aged >65 years. The number of post‐CTC colonoscopies needed to detect 1 case of advanced neoplasia varied from 2 to 4.CONCLUSIONSAge and sex were identified as important independent predictors of advanced neoplasia risk in individuals undergoing screening CTC, whereas BMI and a positive family history of colorectal cancer were not. These results have implications for appropriate patient selection. Cancer 2013;119:2549–2554. © 2013 American Cancer Society.
The remote sensing image enhancement based on nonsubsampled contourlet transform and unsharp masking
Authors: Pu Xiaoting , Jia Zhenhong , Wang Liejun , Hu Yingjie , Yang Jie 
Published: June 2013

SUMMARYTo restrain pseudo‐Gibbs phenomenon, low contrast and blurred phenomenon in the process of image enhancement, a new method based on the nonsubsampled contourlet transform and the unsharp masking is proposed in this paper. The proposed method utilizes the shift‐invariance of nonsubsampled contourlet transform to restrain the pseudo‐Gibbs phenomenon, and then enhance details of the image by unsharp masking. We achieved an increase in image definition by 54.5%, the mean increased by 15.6%, whereas the standard deviation increased by 54.5% compared with the unsharp masking method. To the noisy image, we achieved an increase in image definition by 35.4%, the mean increased by 2.2%, whereas the standard deviation increased by 34.9% compared with the unsharp masking method. Copyright © 2013 John Wiley & Sons, Ltd.
Active contours driven by normalized local image fitting energy
Authors: Peng Yali , Liu Fang , Liu Shigang 
Published: June 2013

SUMMARYIn this paper, a new local region‐based active contour model that is driven by normalized local image fitting energy is proposed. By considering the local image fitting energy to extract the local image information, our model can effectively and efficiently segment images with intensity inhomogeneities. In addition, to keep the smoothness of the level set function, the time‐consuming reinitialization step widely adopted in traditional level set methods can be avoided by introducing a Gaussian filtering process. Experimental results on synthetic and real images demonstrate that the proposed model has much less CPU time and sensitivity to the initial contour than the well‐known local binary fitting model. Copyright © 2013 John Wiley & Sons, Ltd.
Improvement of growth habit and optical properties of rapidly grown KDP crystal by adding diethylene triamine pentacetate acid in growth solution
Authors: Zhu Shengjun , Wang Shenglai , Ding Jianxu , Liu Guangxia , Xu Xinguang 
Published: June 2013

By altering the concentration of a new additive ‐ diethylene triamine pentacetate acid (DTPA) in the growth solution, a series of KDP crystals were obtained by the “point seed” rapid growth method. The growth rates up to about 20 mm/day. Effects of DTPA on the growth habit and optical properties of these as‐grown KDP crystals were investigated. The results reveal that, with the increase of DTPA concentration in growth solution, the contents of impurity metal ions incorporated into crystal and aspect ratio of crystal morphology were both decreased gradually, while the UV transmittance of crystal was enhanced continually. In the presence of moderate concentration of DTPA (100–200 ppm), the solution stability was increased and optical properties of crystal (including optical homogeneity, light scattering and laser damage threshold) were all improved. However excessive doping (>500 ppm) has opposite effects. The impact mechanism was also analyzed combining with the structure of KDP crystal and chemical characteristics of DTPA molecular.
How the development of handedness could contribute to the development of language
Authors: Michel George F. , Babik Iryna , Nelson Eliza L. , Campbell Julie M. , Marcinowski Emily C. 
Published: June 2013

ABSTRACTWe propose a developmental process which may link the development of handedness with the development of hemispheric specialization for speech processing. Using Arbib's proposed sequence of sensorimotor development of manual skills and gestures (that he considers to be the basis of speech gestures and proto‐language), we show how the development of hand‐use preferences in proto‐reaching skills concatenate into object acquisition skills and eventually into role‐differentiated bimanual manipulation skills (that reflect interhemispheric communication and coordination). These latter sensorimotor skills might facilitate the development of speech processing via their influence on the development of tool‐using and object management abilities. © 2013 Wiley Periodicals, Inc. Dev Psychobiol 55: 608–620, 2013.
Age and sex differences in reward behavior in adolescent and adult rats
Authors: Hammerslag Lindsey R. , Gulley Joshua M. 
Published: June 2013

ABSTRACTCompared to adults, adolescents are at heightened risk for drug abuse and dependence. One of the factors contributing to this vulnerability may be age‐dependent differences in reward processing, with adolescents approaching reward through stimulus‐directed, rather than goal‐directed, processes. However, the empirical evidence for this in rodent models of adolescence, particularly those that investigate both sexes, is limited. To address this, male and female rats that were adolescents (P30) or adults (P98) at the start of the experiment were trained in a Pavlovian approach (PA) task and were subsequently tested for the effects of reward devaluation, extinction, and re‐acquisition. We found significant interactions between age and sex: females had enhanced acquisition of PA and poorer extinction, relative to males, while adolescents and females were less sensitive to reward devaluation than male adults. These results suggest that females and adolescents exhibit reward behavior that is more stimulus‐directed, rather than goal‐directed. © 2013 Wiley Periodicals, Inc. Dev Psychobiol 56: 611–621, 2014.
Motherless quail mothers display impaired maternal behavior and produce more fearful and less socially motivated offspring
Authors: Pittet Florent , Le Bot Océane , Houdelier Cécilia , Richard‐Yris Marie‐Annick , Lumineau Sophie 
Published: June 2013

ABSTRACTEarly maternal deprivation impairs the behavioral development of young individuals. Recently, strong differences between mothered and maternally deprived chicks have been reported concerning their emotionality, sociality, and spatial skills. Here we investigated long‐term and cross‐generational impacts of maternal deprivation by comparing the characteristics of the non‐reproductive and the maternal behavior of 22 mothered and 22 non‐mothered adult female Japanese quail (Coturnix c. japonica) and by comparing the behavior of their respective fostered chicks. We reveal that non‐brooded mothers were more fearful and less competent in spatial tasks and expressed impaired maternal care, characterized by more aggression towards chicks, higher activity rates, and more abnormal pacing during the first days of the care period. Chicks' behavior was clearly affected by maternal care inducing strong differences in their fearfulness and social motivation. Our results show both long‐term and cross‐generational impacts of early maternal deprivation in precocial birds. © 2013 Wiley Periodicals, Inc. Dev Psychobiol 56: 622–634, 2014.
Three‐Dimensional Network Mesoporous Nanostructured α‐Manganese Dioxide with High Supercapacitive Performance: Facile, Environmental and Large‐Scale Synthesis
Authors: Yu Li‐Li , Zhu Jun‐Jie , Zhao Jing‐Tai 
Published: June 2013

AbstractMesoporous nanostructured α‐manganese dioxide (MN‐α‐MnO2) powders in a sponge‐like three‐dimensional network have been successfully synthesized in high yields in a simple, template‐free manner at room temperature. Its unique structure has been found to be related to the glucose solution rather than to the KMnO4 solution. A possible mechanism for the formation of MN‐α‐MnO2 by the oxidation of MnO2 precursors cross‐linked by glucose networks is proposed that is supported by experimental results. The electrochemical studies showed that MN‐α‐MnO2 exhibits good electrochemical properties in 1 M Na2SO4 due to its high specific surface area (ca. 220 m2 g–1) and proper pore size distributions (ca. 5 nm), which indicates that it has potential for use as a high‐performance supercapacitor due to its good electrochemical performance, low cost and environmental friendliness.
Domino Reaction of Iodoglycosides: Synthesis of Carbohydrate‐Based Nitroalkenes
Authors: Soengas Raquel G. , Silva Artur M. S. 
Published: June 2013

AbstractHerein we describe a tandem fragmentation/Henry reaction of iodoglycosides, which involves formation of a carbon–carbon double bond and a carbon–carbon single bond. If the fragmentation of methyl 5‐iodo‐D‐ribofuranoside is mediated by zinc/catalytic indium in the presence of bromonitromethane, a separable mixture of a 1‐nitro‐5‐hexene and a 1‐bromo‐1‐nitro‐5‐hexene is obtained in moderate yields with good diastereoselectivities. However, if the reaction is mediated by nBuLi in the presence of nitromethane, the corresponding 1‐nitro‐5‐hexene is obtained as the only product in excellent yield and stereoselectivity in a one‐pot synthetic protocol. This is a general methodology that can be applied to iodopyranoses and iodofuranoses with different protecting groups for the efficient preparation of highly functionalized 1‐nitro‐5‐hexenes or 1‐nitro‐6‐heptenes.