bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement Uncertainty
Authors: Clippinger David 
Published: January 2013

Abstract
Uncertainty is a property of a measurement. Its value allows us to quantify the expected level of dispersion in the quantity being measured. It is an important parameter for quantitatively determining the suitability of a measurement technique. Despite its frequent omission, the uncertainty of a measurement is actually important in all situations where a measured quantity must be trusted with a certain level of confidence. The two methods of evaluating or computing uncertainty have been presented here. These methods are consistent with each other while each possessing its own particular advantages. The ISO approach has the advantage of ease of application and flexibility. All uncertainties are treated identically, allowing for simplicity in approach. Further, the experimentalist may select an appropriate coverage factor or simply report the combined uncertainty and allow the end user of the measurement to determine the suitability of the measurement. The ASME approach requires that the sources of measurement uncertainty be sorted into systematic and random categories.
Iron‐Catalyzed CC Bond Cleavage and CN Bond Formation
Authors: Li Wenjuan , Zheng Xiaojian , Li Zhiping 
Published: January 2013

AbstractA novel approach for CN bond formation was developed by iron‐catalyzed CC bond cleavage. Anilines and sulfonamides reacted smoothly with 2‐substituted 1,3‐diphenylpropane‐1,3‐diones to afford N‐alkylation products, in which the 1,3‐dicarbonyl group acts as a leaving group in the presence of an iron catalyst. The reversible CC bond cleavage plays a driving force to give the thermodynamically stable products. The method is complementary to the previous methods for CN bond formation.
Selective and Practical Oxidation of Sulfides to Diastereopure Sulfoxides: A Combined Experimental and Computational Investigation
Authors: Bottoni Andrea , Calvaresi Matteo , Ciogli Alessia , Cosimelli Barbara , Mazzeo Giuseppe , Pisani Laura , Severi Elda , Spinelli Domenico , Superchi Stefano 
Published: January 2013

AbstractWe describe an effective oxidation of diltiazem (DTZ)‐like molecules (a class of prochiral sulfides with potential pharmacological properties) using m‐chloroperbenzoic acid (MCPBA) as oxidant either in dichloromethane or methanol. An excellent diastereomeric excess of one sulfoxide has been observed “in the absence of any chiral auxiliary”. The stereochemistry of the two diastereomeric sulfoxides has been determined by TDDFT simulations of the experimental electronic circular dichroism (ECD) spectra. A computational DFT study of the reaction mechanism shows that the attack of MCPBA on the two sulfide enantiotopic faces affords two preliminary complexes M1 and M1′. M1 is more stable than M1′ by 3.3 and 3.5 kcal mol−1 in dichloromethane and methanol, respectively, and after equilibration its population must be dominant. Two diastereomeric pathways originate from M1 and M1′ and give two diastereomeric sulfoxides with R and S configurations at the new chiral sulfur, respectively. Since TS (the transition state originating from M1) is more stable than TS′ (the energy gap is 0.7 kcal mol−1 in dichloromethane or methanol), following the Curtin–Hammett principle, the favoured path is the pro‐R channel (M1→TS→M2) affording the (Rc,Rs)‐2a′ product species in agreement with the observed diastereoselectivity. The M1–M1′ and TS–TS′ energy gaps are actually determined by the difference in the hydrogen bond network that features the two species even if the approaching orientation of the two molecules is governed by the interactions between the π systems of oxidant and substrate aromatic rings. The diastereomeric ratio computed on the basis of the energy difference between TS and TS′ (0.7 kcal mol−1) is 63:37, which must be compared to the experimental value 9:1. When we consider free energy differences (2.4 kcal mol−1 in vacuum and 2.9 kcal mol−1 in solution) this theoretical ratio becomes 85:15 and 89:11, respectively, in excellent agreement with the experimental value 9:1.
Transparent low‐density polyethylene/starch nanocomposite films
Authors: Inceoglu Funda , Menceloglu Yusuf Ziya 
Published: January 2013

AbstractLow‐density polyethylene (LDPE)/starch nanocomposite films were prepared by melt extrusion process. The first step includes the preparation of starch–clay nanocomposite by solution intercalation method. The resultant product was then melt mixed with the main matrix, which is LDPE. Maleic anhydride‐grafted polyethylene (MAgPE), produced by reactive extrusion, was used as a compatibilizer between starch and LDPE phases. The effects of using compatibilizer, clay, and plasticizers on physico‐mechanical properties were investigated. The results indicated that the initial intercalation reaction of clay layers with starch molecules, the conversion of starch into thermoplastic starch (TPS) by plasticizers, and using MAgPE as a compatibilizer provided uniform distribution of both starch particles and clay layers, without any need of alkyl ammonium treatment, in LDPE matrix. The nanocomposite films exhibited better tensile properties compared to clay‐free ones. In addition, the transparency of LDPE film did not significantly change in the presence of TPS and clay particles. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Preparation and application of triglyceride plasticizers for poly(vinyl chloride)
Authors: Ye Jinhua , Liu Shuzhen , Xiang Jun , Lei Jingxin , Zhou Changlin 
Published: January 2013

AbstractA series of triglyceride plasticizers were prepared from glycerol, acetic acid, and benzoic acid through a two‐step reaction to develop potential uses of glycerol. The optimum reaction conditions were determined by the esterification of glycerol and acetic acid to produce glyceryl triacetate. When the molar ratio of glycerol to benzoic acid to acetic acid was 1:1:3.5, a novel plasticizer triglyceride mixture (GTM) was successfully synthesized; it had a good plasticizing effect on poly(vinyl chloride) (PVC). The elongation at break of PVC composites containing 80 phr GTM increased around 350%; the corresponding hardness (Shore D) and tensile strength decreased to around 35 D and 20 MPa, respectively. Moreover, the glass‐transition temperature (Tg) of PVC composites containing 40 phr GTM decreased to around 50°C. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Synthesis, characterization, and flocculation performance of anionic polyacrylamide P (AM‐AA‐AMPS)
Authors: Ma Jiangya , Zheng Huaili , Tan Mingzhuo , Liu Liwei , Chen Wei , Guan Qingqing , Zheng Xiaokai 
Published: January 2013

AbstractIn this study, a kind of anionic polyacrylamide (P(AM‐AA‐AMPS)) was synthesized using acrylamide (AM), acrylic acid (AA), and 2‐acrylamido‐2‐methyl propane sulfonic acid (AMPS) under ultraviolet (UV) irradiation. The conditions of the polymerization reaction such as monomer mass ratio, solution pH value, EDTA concentration and urea concentration were investigated by using the single factor approach and an L16 (45) orthogonal array. The structure and morphologies of the copolymer were determined by nuclear magnetic resonance spectrometer (NMR), infrared spectrometer (IR) and scanning electron microscope (SEM). The results show P(AM‐AA‐AMPS) with the intrinsic viscosity of 1.5 × 103 mL g−1 was synthesized at optimal conditions: mass ratio, m(AM) : m(AA) : m(AMPS) of 70 : 10 : 10, pH value of 9.0, EDTA concentration of 0.10% and urea concentration of 0.20%. In addition, P(AM‐AA‐AMPS) had better flocculation efficiency than commercial PAM in sludge dewatering experiment; the minimum filter cake moisture content could be reduced to 65.1%. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
In situ synthesis of nano silver on polyester using NaOH/Nano TiO2
Authors: Allahyarzadeh Vida , Montazer Majid , Nejad Nahid Hemmati , Samadi Nasrin 
Published: January 2013

AbstractAlkali hydrolysis of polyester along with application of nano silver/nano TiO2 to produce hydrolyzed polyester fabric with antibacterial and self‐cleaning properties is a very interesting subject. In this article, a novel idea is introduced to achieve a polyester fabric with self‐cleaning and antibacterial properties with a good feeling handle in one step. The polyester fabric is hydrolyzed in alkali media to enhance the surface activity, improve nanoparticle absorption, and produce ethylene glycol for reducing silver nitrate into nano silver. XRD pattern confirms the presence of nanoparticles with crystal size of 10 nm on the fabric surface and FESEM pictures show the distribution of nanocomposite particles on the fiber surfaces with average size of 54 nm. The degradation of Methylene Blue under daylight irradiation confirms the photoactivity of nano TiO2 on the polyester fabric. Also, very good bactericidal efficiency is obtained against S. aureus and E. coli. Interestingly, the fabric tensile strength improves even with the action of alkali in surface hydrolysis of polyester. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Carbohydrate–PNA and Aptamer–PNA Conjugates for the Spatial Screening of Lectins and Lectin Assemblies
Authors: Scheibe Christian , Wedepohl Stefanie , Riese Sebastian B. , Dernedde Jens , Seitz Oliver 
Published: January 2013

AbstractNucleic acid architectures offer intriguing opportunities for the interrogation of structural properties of protein receptors. In this study, we performed a DNA‐programmed spatial screening to characterize two functionally distinct receptor systems: 1) structurally well‐defined Ricinus communis agglutinin (RCA120), and 2) rather ill‐defined assemblies of L‐selectin on nanoparticles and leukocytes. A robust synthesis route that allowed the attachment both of carbohydrate ligands—such as N‐acetyllactosamine (LacNAc), sialyl‐Lewis‐X (sLeX), and mannose—and of a DNA aptamer to PNAs was developed. A systematically assembled series of different PNA–DNA complexes served as multivalent scaffolds to control the spatial alignments of appended lectin ligands. The spatial screening of the binding sites of RCA120 was in agreement with the crystal structure analysis. The study revealed that two appropriately presented LacNAc ligands suffice to provide unprecedented RCA120 affinity (KD=4 μM). In addition, a potential secondary binding site was identified. Less dramatic binding enhancements were obtained when the more flexible L‐selectin assemblies were probed. This study involved the bivalent display both of the weak‐affinity sLeX ligand and of a high‐affinity DNA aptamer. Bivalent presentation led to rather modest (sixfold or less) enhancements of binding when the self‐assemblies were targeted against L‐selectin on gold nanoparticles. Spatial screening of L‐selectin on the surfaces of leukocytes showed higher affinity enhancements (25‐fold). This and the distance–activity relationships indicated that leukocytes permit dense clustering of L‐selectin.
Pitfalls associated with the use of current recommendations for fluoroscopy‐guided common femoral artery access
Authors: Yaganti Vamsee , Mejevoi Nicolai , Hasan Omar , Cohen Marc , Wasty Najam 
Published: January 2013

BackgroundVascular access complications remain the leading cause of morbidity after cardiac catheterization procedures. Fluoroscopy‐guided vascular access has been recommended to reduce these complications. However, the use of current recommendations still results in arterial access above the inferior epigastric artery (IEA) (high stick) or below the common femoral artery (CFA) bifurcation (low stick).ObjectivesThe goal of our study was to evaluate the influence of patient characteristics like age, body mass index, and pelvic anatomy on current recommendations.MethodsWe prospectively collected clinical, anatomic, and angiographic data on 631 consecutive patients who underwent coronary and noncoronary procedures via CFA access. Anatomic location of IEA loop, CFA bifurcation, public tubercle (PT), and anterior superior iliac spine were identified in relationship to the femoral head Location of IEA loop was used as a surrogate for inguinal ligament (IL).ResultsApproximately 12% of patients had a low‐lying IEA loop (group B). These patients had a significantly higher BMI compared with patients with IEA loop above the centerline of femoral head (group A) (P = 0.018). The anatomic location of PT was below the lower border of femoral head significantly more frequently in group B compared to group A (P < 0.0001). Fifteen percent of patients had a high CFA bifurcation. On clinical follow‐up during index hospitalization, there was no significant difference between the two groups, in terms of complications including retroperitoneal hemorrhage, access site hematoma >5 cm, bleeding requiring transfusion or pseudoaneurysm.ConclusionsAnatomic location of PT on fluoroscopy can be used as an additional surrogate to predict the location of IL. Patients with high BMI have a low lying IL, which may predispose them to “high sticks.” The location of IEA cannot be used as a surrogate for IL in all patients. © 2012 Wiley Periodicals, Inc.
Enhancement of Catalyst Performance in the Direct Propene Epoxidation: A Study into Gold–Titanium Synergy
Authors: Chen Jiaqi , Halin Sander J. A. , Pidko Evgeny A. , Verhoeven M. W. G. M. (Tiny) , Ferrandez Dulce M. Perez , Hensen Emiel J. M. , Schouten Jaap C. , Nijhuis T. Alexander 
Published: January 2013

AbstractEnhanced productivity toward propene oxide in the direct propene epoxidation with hydrogen and oxygen over gold nanoparticles supported on titanium‐grafted silica was achieved by adjusting the gold–titanium synergy. Highly isolated titanium sites were obtained by lowering the titanium loading grafted on silica. The tetrahedrally coordinated titanium sites were found to be favorable for attaining small gold nanoparticles and thus a high dispersion of gold. The improved productivity of propene oxide can be attributed to the increased amount of the interfacial AuTi sites. The active hydroperoxy intermediate is competitively consumed by epoxidation and hydrogenation at the AuTi interface. A higher propene concentration is favorable for a lower water formation rate and a higher formation rate of propene oxide. Propene hydrogenation, if occurring, can be switched off by a small amount of carbon monoxide.
Theoretical Study of the Oxidation of Phenolates by the [Cu2O2(N,N′‐di‐tert‐butylethylenediamine)2]2+ Complex
Authors: Liu Yan Fang , Yu Jian Guo , Siegbahn Per E. M. , Blomberg Margareta R. A. 
Published: January 2013

AbstractExperiments have shown that the μ‐η2:η2‐peroxodicopper(II) complex [Cu2O2(N,N′‐di‐tert‐butylethylenediamine)2]2+ rapidly oxidizes 2,4‐di‐tert‐butylphenolate into a mixture of catechol and quinone and that, at the extreme temperature of −120 °C, a bis‐μ‐oxodicopper(III)phenolate intermediate, labeled complex A, can be observed. These experimental results suggest a new mechanism of action for the dinuclear copper‐containing enzyme tyrosinase, involving an early OO bond‐cleavage step. However, whether phenolate binding occurs before or after the cleavage of the OO bond has not been possible to answer. In this study, hybrid density functional theory is used to study the synthetic reaction and, based on the calculated free‐energy profile, a mechanism is suggested for the entire phenolate‐oxidation reaction that agrees with the experimental observations. Most importantly, the calculations show that the very first step in the reaction is the cleavage of the OO bond in the peroxo complex and that, subsequently, the phenolate substrate coordinates to one of the copper ions in the bis‐μ‐oxodicopper(III) complex to yield the experimentally characterized phenolate intermediate (A). The oxidation of the phenolate substrate into a quinone then occurs in three steps: 1) CO bond formation, 2) coupled internal proton and electron transfer, and 3) electron transfer coupled to proton transfer from an external donor (acidic workup, experimentally). The first of these steps is rate limiting for the decay of complex A, with a calculated free‐energy barrier of 10.7 kcal mol−1 and a deuterium kinetic isotope effect of 0.90, which are in good agreement with the experimental values of 11.2 kcal mol−1 and 0.83(±0.09). The tert‐butyl substituents on both the phenol substrate and the copper ligands need to be included in the calculations to give a correct description of the reaction mechanism.
Collective Total Synthesis of Englerin A and B, Orientalol E and F, and Oxyphyllol: Application of the Organocatalytic [4+3] Cycloaddition Reaction
Authors: Wang Jie , Chen Shu‐Guang , Sun Bing‐Feng , Lin Guo‐Qiang , Shang Yong‐Jia 
Published: January 2013

AbstractThe concise collective total synthesis of englerin A and B, orientalol E and F, and oxyphyllol has been accomplished in 10–15 steps, with the total synthesis of orientalol E and oxyphyllol being achieved for the first time. The success obtained was enabled by the realization of the [4+3] cycloaddition reaction of 9 and 10. Other features of the synthesis include 1) the intramolecular Heck reaction to access the azulene core, 2) the epoxidation–SN2′ reduction sequence to access the allylic alcohol, 3) the efficient regioselective and stereoselective formal hydration of the bridging CC bond in the synthesis of englerins, and 4) the late‐stage chemo‐ and stereoselective CH oxidation in the synthesis of orientalol E. The total synthesis of these natural products has enabled the structural revision of oxyphyllol and established the absolute stereochemical features of the organocatalytic [4+3] cycloaddition reaction. The identification of 5 as the natural product oxyphyllol, the success in converting 5 to orientalol E, along with the fact that englerins and oxyphyllol were isolated from plants of the same genus Phyllanthus gives support to our proposed biosynthetic pathways. This work may enable detailed biological evaluations of these natural products and their analogues and derivatives, especially of their potential in the fight against renal cell carcinoma (RCC).
Syntheses and Characterization of New Vinyl‐Borylene Complexes by the Hydroboration of Alkynes with [(μ3‐BH)(Cp*RuCO)2(μ‐CO)Fe(CO)3]
Authors: Bose Shubhankar Kumar , Roy Dipak Kumar , Shankhari Pritam , Yuvaraj K. , Mondal Bijan , Sikder Amrita , Ghosh Sundargopal 
Published: January 2013

AbstractRoom temperature photolysis of a triply‐bridged borylene complex, [(μ3‐BH)(Cp*RuCO)2(μ‐CO)Fe(CO)3] (1 a; Cp*=C5Me5), in the presence of a series of alkynes, 1,2‐diphenylethyne, 1‐phenyl‐1‐propyne, and 2‐butyne led to the isolation of unprecedented vinyl‐borylene complexes (Z)‐[(Cp*RuCO)2(μ‐CO)B(CR)(CHR′)] (2: R, R′=Ph; 3: R=Me, R′=Ph; 4: R, R′=Me). This reaction permits a hydroboration of alkyne through an anti‐Markovnikov addition. In stark contrast, in the presence of phenylacetylene, a metallacarborane, closo‐[1,2‐(Cp*Ru)2(μ‐CO)2{Fe2(CO)5}‐4‐Ph‐4,5‐C2BH2] (5 a), is formed. A plausible mechanism has been proposed for the formation of vinyl‐borylene complexes, which is supported by density functional theory (DFT) methods. Furthermore, the calculated 11B NMR chemical shifts accurately reflect the experimentally measured shifts. All the new compounds have been characterized in solution by mass spectrometry and IR, 1H, 11B, and 13C NMR spectroscopies and the structural types were unequivocally established by crystallographic analysis of 2, 5 a, and 5 b.
Discovery of Pyridone‐Based Histone Deacetylase Inhibitors: Approaches for Metabolic Stability
Authors: Cho Misun , Choi Eunhyun , Yang Jee Sun , Lee Chulho , Seo Jeong Jea , Kim Beom Seok , Oh Soo Jin , Kim Hwan Mook , Lee Kiho , Park Song‐Kyu , Kwon Ho Jeong , Han Gyoonhee 
Published: January 2013

AbstractHistone deacetylases (HDACs) are important enzymes in epigenetic regulation and are therapeutic targets for cancer. Most zinc‐dependent HDACs induce proliferation, dedifferentiation, and anti‐apoptotic effects in cancer cells. We designed and synthesized a new series of pyridone‐based HDAC inhibitors that have a pyridone ring in the core structure and a conjugated system with an olefin connecting the hydroxamic acid moiety. Consequently, most of the selected pyridone‐based HDAC inhibitors showed similar or higher inhibition profiles in addition to remarkable metabolic stability against hydrolysis relative to the corresponding lactam‐based HDAC inhibitors. Furthermore, the selectivity of the novel pyridine‐based compounds was evaluated across all of the HDAC isoforms. One of these compounds, (E)‐N‐hydroxy‐3‐{1‐[3‐(naphthalen‐2‐yl)propyl]‐2‐oxo‐1,2‐dihydropyridin‐3‐yl}acrylamide, exhibited the highest level of HDAC inhibition (IC50=0.07 μM), highly selective inhibition of class I HDAC1 and class II HDAC6 enzymes, metabolic stability in mouse liver microsomal studies, and effective growth inhibition of various cancer cell lines. Docking studies indicated that a long alkyl linker and bulky hydrophobic cap groups affect in vitro activities. Overall, the findings reported herein regarding pyridone‐based HDAC inhibitors can be used to guide future research efforts to develop new and effective anticancer therapeutics.
Imidazole‐ and Benzimidazole‐Based Inhibitors of the Kinase IspE: Targeting the Substrate‐Binding Site and the Triphosphate‐Binding Loop of the ATP Site
Authors: Mombelli Paolo , Le Chapelain Camille , Munzinger Noah , Joliat Evelyne , Illarionov Boris , Schweizer W. Bernd , Hirsch Anna K. H. , Fischer Markus , Bacher Adelbert , Diederich François 
Published: January 2013

AbstractThe enzymes of the mevalonate‐independent biosynthetic pathway to isoprenoids are attractive targets for the development of new drug candidates, in particular against malaria and tuberculosis, because they are present in major human pathogens but not in humans. Herein, the structure‐based design, synthesis, and biological evaluation of a series of inhibitors featuring a central imidazole or benzimidazole scaffold for the kinase IspE from E. coli, a model for the corresponding malarial enzyme, are described. Optimization of the binding preferences of the hydrophobic sub‐pocket at the substrate‐binding site allowed IC50 values in the lower micromolar range to be reached. Structure–activity relationship studies using a 1,2‐disubstituted imidazole central core revealed that alicyclic moieties fit the sub‐pocket better than acyclic aliphatic and aromatic residues. The phosphate‐binding region in the ATP‐binding site of IspE, a neutral glycine‐rich loop, was addressed for the first time by an additional vector attached to the central core. Polar functional groups, such as trifluoromethyl or nitriles, were introduced to undergo orthogonal dipolar interactions with the amide groups in the loop. Alternatively, small hydrogen‐bond‐accepting heterocyclic residues, capable of binding to the convergent NH groups in the loop, were explored. The biological data showed slightly improved inhibitory potency in some cases and confirmed the challenges in addressing, with gain in binding affinity, the highly water‐exposed sections of enzyme active sites, such as the glycine‐rich loop of IspE.