bluuebunny/crossref_metadata_2025_split huggingface dataset:
Titanium K‐Edge XANES Analysis to Unravel the Local Structure of Alkene Epoxidation Titanium‐Polysiloxane Homogeneous Catalysts
Authors: Blanco‐Brieva Gema , Capel‐Sanchez Mari Carmen , Campos‐Martín Jose M. , Fierro Jose L. G. , Lede Eduardo J. , Adrini L. , Requejo Felix G. 
Published: December 2003

AbstractWe describe the synthesis of highly effective homogeneous catalysts for the epoxidation of alkenes with organic hydroperoxide and their detailed characterization with the X‐ray absorption near‐edge spectroscopy (XANES) technique. Prepeaks at Ti K‐edge XANES spectra of the catalysts showed a shift towards higher photon energy and a simultaneous drop in relative intensity with the increasing number of nearest oxygen neighbours around titanium. PCA analysis of Ti K‐edge XANES spectra revealed that the catalysts can be grouped in four distinct regions according to their structural characteristics. These structural differences revealed by Ti K‐edge XANES spectra can be ascribed to the procedure employed in catalyst synthesis. In a preliminary attempt to explain catalytic performance, FTIR, UV‐visible and XPS spectroscopic techniques were used to characterize the chemical structures developed on the catalysts; however, no correlation between reactivity and surface and/or bulk structures was found. Only the Ti K‐edge XANES spectra of these Ti‐polysiloxanes afforded a successful description of the local structure of TiIV centers due to their sensitivity in distinguishing different electronic structures for Ti atoms even under slight variations in their surroundings.
The Effect of pH Control on the Selective Ruthenium‐Catalyzed Oxidation of Ethers and Alcohols with Sodium Hypochlorite
Authors: Gonsalvi Luca , Arends Isabel W. C. E. , Moilanen Pasi , Sheldon Roger A. 
Published: December 2003

AbstractHighly selective oxidations of ethers to esters or lactones and of secondary alcohols to ketones were achieved using catalytic amounts of various Ru precursors and the theoretical amount of NaOCl. Reactions were carried out in biphasic solvent mixtures at constant pH 9–9.5 via either feed‐on‐demand addition of HCl and NaOH or in the presence of NaHCO3/Na2CO3 buffer. The catalyst could be easily recycled for at least 4 times with only minor loss in selectivity. Products were generally recovered by simple phase separation and evaporation of the organic solvent. The effects of catalyst precursor, additives and pH control method are also described.
Tail‐Tied Ligands: An Immobilized Analogue of (R)‐2‐Piperidino‐1,1,2‐triphenylethanol with Intact High Catalytic Activity and Enantioselectivity
Authors: Pericàs Miquel A. , Castellnou David , Rodríguez Israel , Riera Antoni , Solà Lluís 
Published: December 2003

AbstractA functional analogue of (R)‐2‐piperidino‐1,1,2‐triphenylethanol was synthesized and anchored to different polymeric supports by a position remote from the active region. This strategy, leading to what we call a tail‐tied ligand, allows for the achievement of the optimal transition state geometry in the catalytic process. The catalytic activity of the resulting heterogenized ligands was investigated by online FTIR analysis. The optimum polymer was assayed in the addition reaction of diethylzinc to a large family of aldehydes rendering essentially intact high catalytic activity and enantioselectivity compared to its homogeneous counterpart.
Electrophilic Aromatic Nitration Using a Mixed Catalyst of Lithium, Molybdenum, Ytterbium on Silica Gel
Authors: Shi Min , Cui Shi‐Cong 
Published: December 2003

AbstractA novel mixed catalyst of LiClO4 (15% w/w), Yb(OPf)3 (15% w/w, Pf=perfluorooctanesulfonyl), MoO3 (15% w/w) on silica gel for electrophilic aromatic nitration reaction has been explored. The nitration reactions were accomplished by this mixed catalyst and nitric acid under solvent‐free conditions. Moreover, the mixed catalyst can be easily recovered from the aqueous layer by heating in an oven and reused for the next nitration reaction.
Microwave‐Assisted Oxidation of Side Chain Arenes by MagtrieveTM
Authors: Lukasiewicz Marcin , Bogdal Dariusz , Pielichowski Jan 
Published: December 2003

AbstractA commercial tetravalent chromium dioxide (MagtrieveTM) as a magnetically retrievable oxidant is shown to be a very useful compound for microwave‐assisted and conventional transformation of aromatic and alkyl aromatic molecules into the corresponding aryl ketones, quinones or lactones.
Kinetic Enzymatic Resolution of Cyclopropane Derivatives
Authors: Pietruszka Jörg , Rieche Anja C. M. , Wilhelm Thorsten , Witt Andreas 
Published: December 2003

AbstractThe kinetic enzymatic resolution of various cyclopropane derivatives was systematically investigated. The study focused on synthetically useful cyclopropylmethanols (e.g., 18a/j or 19a/j) as well as some rarely investigated cyclopropanols (e.g., 24/25 or 27). The combination of enantioselective catalytic or diastereoselective synthesis of enantiomerically enriched compounds with enzymatic approaches ultimately led to the most convenient route to enantiomerically pure starting materials. Again, this was especially proven for the synthesis of cyclopropanols 18a/j and 19a/j. Key to the successful investigation was to rigorously establish an analytical tool for the analysis of enantiomeric composition of reaction mixtures.
Optimal Heck Cross‐Coupling Catalysis: A Pseudo‐Pharmaceutical Approach
Authors: Burello Enrico , Rothenberg Gadi 
Published: December 2003

AbstractThe problem of predicting the activity of ligands and solvents in homogeneous catalysis is addressed. A systematic selection method for ligands and solvents is presented, using a combination of stereoelectronic and electrotopological descriptors to describe the ligands and solvents in a set of 500 Heck reactions. Libraries of ‘virtual ligands’ and ‘virtual solvents’ are projected on the reaction space, and their reactivity is then predicted using multivariate models. The applications of this approach to combinatorial catalysis and reducing the amount of ‘garbage data’ are discussed.
Thermo‐oxidative degradation studies of ternary blends of polyethylenes
Authors: Srivastava Deepak , Kumar Pramod , Mathur G. N. 
Published: January 2004

AbstractFilms of low‐density polyethylene (LDPE) and high‐density polyethylene (HDPE) each containing 25 wt % of linear low‐density polyethylene (LLDPE) were extruded by melt blending in a single screw extruder (L/D ratio = 20:1). The samples were aged at 55, 70, 85, and 100°C for different time periods up to 600 h. The change in molecular structure and formation of oxygenated and unsaturated groups during thermo‐oxidative degradation were investigated by infrared spectroscopy. Viscosity‐average molecular weight (M̄v) was found to decrease at slower rate in the initial hours of ageing, whereas on prolonged ageing, it decreased at a faster rate. In some blend samples, the tensile strength and elongation at break initially increased up to certain hours of ageing, and then decreased while in some blends both tensile strength and elongation‐at‐break varied differently. Increase in percent gel content supports the formation of cross‐links between the molecular chains. Thermal stability of the samples also decreased with ageing time and temperature. © 2004 Wiley Periodicals, Inc. Adv Polym Techn 23: 59–70, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.10067
Effect of mape on the mechanical properties of rubber wood fiber/thermoplastic natural rubber composites
Authors: Sameni J. K. , Ahmad S. H. , Zakaria S. 
Published: January 2004

AbstractRubber wood fiber/reinforced thermoplastic natural rubber (RWF/TPNR) composites were prepared. A blend of natural rubber with high‐density polyethylene was prepared by melt blending the materials in the internal mixer of Brabender Plasticorder machine. RWF and TPNR were mixed with different fractions of fiber (0, 5, 10, 20, and 30%) in the internal mixer. To investigate the influence of coupling agent on the mechanical properties, concentrations of maleic anhydride polyethylene (MAPE) were employed in the composites. The mechanical properties and morphology of composite material were characterized with tensile machine and scanning electron microscope, respectively. The results showed that the addition of MAPE has a positive effect on the tensile strength and Young's modulus while the maximum strain was reduced. SEM micrographs showed good adhesion between RWF and TPNR when the coupling agent was applied. © 2004 Wiley Periodicals, Inc. Adv Polym Techn 23: 18–23, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.10070
Vinyl ester‐based three‐component IPNs for glass fibre reinforced composite applications
Authors: Parmar Jayant S. , Patel Girish R. , Patel Alpesh K. 
Published: January 2004

AbstractThree‐component interpenetrating polymer network (IPN) matrix based glass fiber reinforced composites (GRC) have been prepared from the vinyl ester of an epoxy novolac resin (VEN), diglycidyl ether of bisphenol‐A (DGEBA) (an epoxy resin), and methyl methacrylate (MMA) (a vinyl monomer). 2,2′‐Azobisisobutyronitrile (AIBN) is employed as the initiator for both MMA and vinyl ester (VEN) resins, while DDM (diamino diphenyl methane) is employed for curing of DGEBA. All the IPNs and glass fiber reinforced composites based on these IPNs were characterized and are found to have good resistance to chemical reagents, good thermal stability, and good mechanical properties. © 2004 Wiley Periodicals, Inc. Adv Polym Techn 23: 71–75, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.10071
Studies on swelling properties of wood/polymer composites based on agro‐waste and novolac
Authors: Mishra S. , Naik J. B. , Patil Y. P. 
Published: January 2004

AbstractIn the present work the natural and maleic anhydride esterified fibers of banana, hemp, and sisal are used as reinforcers in novolac resin in the ratio of 40:60 (wt/wt) respectively. Absorption of water and steam in these wood/polymer composites is studied. The absorption of water increases with increase in time from 2 to 30 h in all fiber composites tested. Amongst all the composites, the maximum absorption of water is found in hemp fiber composite and the minimum in maleic anhydride treated sisal fiber composite. The maleic anhydride esterified fiber composite shows less absorption of water than the untreated fiber composites. Amongst all six composites, steam absorption is maximum in untreated hemp fiber composite and minimum in maleic anhydride treated banana fiber composite. Steam absorption in maleic anhydride treated fiber composites is higher than the water absorption in respective fiber composites. Untreated fiber composites show more absorption of steam in comparison to maleic anhydride treated fiber composites. © 2004 Wiley Periodicals, Inc. Adv Polym Techn 23: 46–50, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.10073
NMR‐Methoden zum strukturgestützten Wirkstoff‐Design
Authors: Homans Steve W. 
Published: December 2003

AbstractDie biomolekulare NMR‐Spektroskopie wurde in den vergangenen Jahren eindrucksvoll weiterentwickelt und ist inzwischen zu einer extrem leistungsstarken Methode zur Untersuchung von Strukturen, Dynamik und Wechselwirkungen von Biomolekülen gereift. Frühere Einschränkungen hinsichtlich der Molekülgröße sind weitgehend überwunden, sodass mittlerweile Systeme von bis zu 900 kDa untersucht wurden. Die NMR‐Spektroskopie hat sich als effiziente Methode für das schnelle Liganden‐Screening bewährt, interessante Perspektiven für eine Anwendung bieten sich außerdem beim strukturbasierten Wirkstoff‐Design an, z. B. zur raschen Bestimmung von globalen Proteinfaltungen, zur Strukturcharakterisierung von Ligand‐Protein‐Komplexen und zur Ableitung von thermodynamischen Parametern. Ein wichtiger Vorteil der Methode ist, dass Wechselwirkungen in Lösung untersucht werden und auf eine zeitaufwändige Kristallisation verzichtet werden kann. Dieser Aufsatz konzentriert sich auf eine Anzahl neuer Entwicklungen und zeigt auf, wie mithilfe der NMR‐Spektroskopie Engstellen in der gegenwärtigen strukturbasierten Wirkstoffsuche passiert werden können.
NMR Spectroscopy Tools for Structure‐Aided Drug Design
Authors: Homans Steve W. 
Published: December 2003

AbstractBiomolecular NMR spectroscopy has expanded dramatically in recent years and is now a powerful tool for the study of structure, dynamics, and interactions of biomolecules. Previous limitations with respect to molecular size are no longer a primary barrier, and systems as large as 900 kDa were recently studied. NMR spectroscopy is already well‐established as an efficient method for ligand screening. A number of recently developed techniques show promise as aids in structure‐based drug design, for example, in the rapid determination of global protein folds, the structural characterization of ligand–protein complexes, and the derivation of thermodynamic parameters. An advantage of the method is that all these interactions can be studied in solution—time‐consuming crystallization is not necessary. This Review focuses on recent developments in NMR spectroscopy and how they might be of value in removing some of the current “bottlenecks” in structure‐based drug discovery.
Genetic approach to the role of cysteine proteases in the expansion of abdominal aortic aneurysms
Authors: Eriksson P , Jones K G , Brown L C , Greenhalgh R M , Hamsten A , Powell J T 
Published: January 2004

Abstract

Background
The elastinolytic cysteine proteases, including cathepsins S and K, are overexpressed at sites of arterial elastin damage. Cystatin C, an inhibitor of these enzymes, is expressed in arterial smooth muscle cells; an imbalance in cystatin C has been implicated in the aortic wall degeneration observed in abdominal aortic aneurysms (AAAs). The aim of the study was to investigate the impact of a polymorphism in the signal peptide of the cystatin C gene on the growth of small AAAs.

Methods
Some 424 patients with a small AAA (4·0–5·5 cm) were monitored for AAA growth by ultrasonography and provided a DNA sample for analysis of the + 148 G &gt; A polymorphism in the cystatin C signal peptide and the—82 G &gt; C polymorphism in the gene promoter. The median length of follow-up was 2·8 years and AAA growth rates were calculated by linear regression analysis.

Results
For patients of + 148 GG (n = 263), GA (n = 147) and AA (n = 20) genotypes, the mean(s.d.) AAA growth rates were 0·37(0·29), 0·37(0·23) and 0·30(0·26) cm, and initial diameters were 4·58(0·35), 4·58(0·35) and 4·62(0·36) cm, respectively. Patients of + 148 AA genotype had a slower aneurysm growth rate (unadjusted P = 0·058; after adjustment for age, sex, initial AAA diameter and smoking, P = 0·027). There also was a trend for the rare homozygotes of the—82 C allele to have slower AAA growth (adjusted P = 0·055). Smoking history had a stronger association with aneurysm growth (P = 0·003).

Conclusion
There was a weak association between variation in the cystatin C gene and AAA growth. Medical strategies to limit AAA growth might include the inhibition of cysteine proteases.
Preoperative probability model for predicting overall survival after resection of pulmonary metastases from colorectal cancer
Authors: Kanemitsu Y , Kato T , Hirai T , Yasui K 
Published: January 2004

Abstract

Background
The aim of this study was identify readily available factors most helpful in predicting survival and to develop a prognostic nomogram for patients with pulmonary metastases from colorectal cancer who are candidates for thoracotomy.

Methods
Pretreatment data on 313 patients with metastases who underwent thoracotomy were analysed. Fourteen preoperative clinical and pathological variables were used to develop a probability model, in which their association with 3-year survival was tested. A nomogram to predict median, 1- and 3-year survival was constructed and validated internally using the concordance index (c-index). The nomogram was then validated with an external data set.

Results
Five variables were identified as independent predictors of 3-year survival: prethoracotomy carcinoembryonic antigen level, number of pulmonary tumours, presence of hilar or mediastinal tumour-infiltrated lymph nodes, histology of the primary tumour and presence of extrathoracic disease. The nomogram was well calibrated for predicting 3-year overall survival. The internal validated c-index of the nomogram was 0·72. Applied to another data set, the external validated c-index was 0·66.

Conclusion
This model has moderate predictive ability to discriminate between patients who are likely to survive after thoracotomy for pulmonary metastases from colorectal cancer.
Randomized clinical trial comparing level II and level III axillary node dissection in addition to mastectomy for breast cancer
Authors: Tominaga T , Takashima S , Danno M 
Published: January 2004

Abstract

Background
In addition to mastectomy, level II and level III axillary node dissection procedures are performed widely in Japan. A randomized clinical trial was performed to determine which procedure was more effective.

Methods
One group of women had resection of the pectoralis minor muscle and dissection of level I, II and III axillary lymph nodes (level III dissection). In a second group, the pectoralis minor muscle was left intact and level III axillary lymph node dissection was not performed (level II dissection). A total of 1209 women with stage II breast cancer were enrolled in the study and randomly assigned to one of the two groups.

Results
The 10-year cumulative survival rate was 86·6 per cent after level II and 85·7 per cent after level III axillary dissection (hazard ratio (HR) 1·02; P = 0·931, log rank test). The 10-year disease-free survival rate was 73·3 and 77·8 per cent respectively (HR 0·94, P = 0·666). Overall survival and disease-free survival rates in the two groups were similar after both procedures. The duration of surgery was significantly shorter (P &lt; 0·001) and blood loss was significantly less (P = 0·001) after level II dissection. In a survey of patients' symptoms on follow-up, no significant differences were found between the two procedures.

Conclusion
The addition of pectoralis minor muscle resection and level III axillary lymph node dissection to mastectomy for stage II breast cancer did not improve overall or disease-free survival rates.
Randomized clinical trial of lightweight composite mesh for Lichtenstein inguinal hernia repair
Authors: Post S , Weiss B , Willer M , Neufang T , Lorenz D 
Published: January 2004

Abstract

Background
Almost half the patients who undergo hernia repair with mesh report a feeling of stiffness and a foreign body in the groin. This study evaluated whether patients noticed any difference between lightweight and standard polypropylene mesh for the repair of inguinal hernia.

Methods
Patients scheduled for elective repair of unilateral or bilateral, primary or recurrent inguinal hernia by the Lichtenstein technique were randomized to receive either a conventional densely woven polypropylene mesh (100–110 g/m2) or a lightweight composite multifilament mesh (polypropylene 27–30 g/m2). Quality of life was assessed using Short Form 36 before operation and 6 months after surgery. Pain was assessed by means of a visual analogue scale 2 days and 6 months after surgery. The primary outcome measure was the feeling of a foreign body in the groin at 6 months.

Results
Some 122 hernias were randomized; 117 were included in the analysis of perioperative data, and 106 were re-examined after 6 months. There were no differences between the treatment groups with respect to early and late surgical complications. Use of lightweight mesh was associated with significantly less pain on exercise after 6 months (P = 0·042). In addition, fewer patients reported the feeling of a foreign body after repair with lightweight mesh (17·2 versus 43·8 per cent with conventional mesh; P = 0·003). Quality of life was improved significantly at 6 months compared with the preoperative assessment, and there were no differences between the treatment groups.

Conclusion
Lightweight polypropylene mesh may be preferable for Lichtenstein repair of inguinal hernia. Larger cohorts with longer follow-up are needed before it can be recommended for routine use.
Damage control laparotomy
Authors: Finlay I G , Edwards T J , Lambert A W 
Published: January 2004

Abstract

Background
Damage Control Surgery (DCS) is well established in the management of trauma. This study assessed the results of DCS in the management of critically ill patients who had not had trauma.

Methods
This was a prospective series of patients treated by DCS. The Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (POSSUM) and Portsmouth predictor equation (P-POSSUM) were used to predict the risk of death, which was compared with the observed mortality rate.

Results
Fourteen patients were studied. Nine had sepsis from gastrointestinal perforation. Eight of these underwent bowel resection without anastomosis or stoma formation at the initial laparotomy. Six patients later underwent bowel anastomosis and two had an end stoma formed at second laparotomy. A further three patients had a ruptured aortic aneurysm, one had a reactionary haemorrhage after elective aortic surgery, and one had a retroperitoneal bleed; all required haemostatic packing that was removed at second laparotomy. Mortality rates predicted by POSSUM and P-POSSUM scoring were 64·5 and 49·6 per cent respectively. One patient (7·1 per cent) died after operation, giving an observed mortality rate significantly lower than predicted (P = 0·002 and P = 0·038 versus values predicted by POSSUM and P-POSSUM, respectively).

Conclusion
The use of DCS in the treatment of critically ill patients resulted in a lower mortality rate than that predicted by POSSUM or P-POSSUM. DCS should not be restricted to trauma.
Randomized clinical trial investigating the use of drains and fibrin sealant following surgery for breast cancer
Authors: Jain P K , Sowdi R , Anderson A D G , MacFie J 
Published: January 2004

Abstract

Background
Despite limited evidence, closed suction drainage is often used to reduce the risk of seroma formation after breast cancer surgery. The aim of this study was to evaluate the effect of drains and fibrin sealant on the incidence of seroma formation.

Methods
A total of 116 patients undergoing surgery for breast cancer were randomized to receive suction drainage (group 1; n = 58), or to receive no drain (n = 58). Patients allocated to receive no drain were further randomized to have fibrin sealant applied to the dissected area (group 2; n = 29), or to no intervention (group 3; n = 29). Outcome measures were incidence and volume of postoperative seroma, length of hospital stay and postoperative pain scores.

Results
There was no significant difference in the incidence of seroma between group 1 (15 of 58) and either group with no drains (ten of 29 in group 2; 12 of 29 in group 3). There was a significant reduction in hospital stay and postoperative pain scores in patients who did not have a drain. Following mastectomy without a drain, the use of fibrin sealant was associated with a significant reduction in the incidence and total volume of seroma (190 versus 395 ml; P = 0·012).

Conclusion
Drains did not prevent seroma formation, and were associated with a longer postoperative stay and higher pain scores after surgery for breast cancer. In patients who had mastectomy the use of fibrin sealant reduced the rate of seroma formation.