bluuebunny/crossref_metadata_2025 huggingface dataset:
Total Hip Replacement due to Primary Osteoarthritis in Relation to Cumulative Occupational Exposures and Lifestyle Factors: A Nationwide Nested Case–Control Study
Authors: Rubak Tine S. , Svendsen Susanne W. , Søballe Kjeld , Frost Poul
Published: March 2014

Objective

To investigate the risk of total hip replacement (THR) due to primary osteoarthritis in relation to cumulative occupational mechanical exposures and lifestyle factors.

Methods

Using register information, we identified first‐time THR cases within the Danish working population in 2005–2006. For each case, 2 age‐ and sex‐matched controls were drawn. Persons within 2,500 randomly selected case–control sets received a questionnaire about job history, weight at age 25 years, present weight and height, smoking, and sports activities at age 25 years. The job history was combined with a job exposure matrix. Cumulative exposure estimates were expressed according to the pack‐year concept of smoking (e.g., cumulative lifting was expressed as ton‐years). We used conditional logistic regression for statistical analyses.

Results

In total, 1,776 case–control sets (71%) were available for analysis. The adjusted odds ratio (OR) for exposure to ≥20 ton‐years was 1.35 (95% confidence interval [95% CI] 1.05–1.74) for men and 1.00 (95% CI 0.73–1.41) for women. Standing/walking and whole body vibration showed no associations. The adjusted OR for body mass index (BMI) ≥30 kg/m2 at age 25 years was 2.44 (95% CI 1.38–4.32) for men and 5.12 (95% CI 2.30–11.39) for women. The corresponding adjusted ORs for an increase in BMI of ≥10 kg/m2 since age 25 years were 2.16 (95% CI 1.25–3.70) and 2.46 (95% CI 1.47–4.13). Sports participation showed weak positive associations, while pack‐years of smoking showed no associations.

Conclusion

The results indicated a modest increase in risk of THR in relation to cumulative lifting among men and an increased risk in relation to a high BMI at age 25 years and to a gain in BMI in both sexes.
Relationship Between Strength, Pain, and Different Measures of Functional Ability in Patients With End‐Stage Hip Osteoarthritis
Authors: Zeni Joseph , Abujaber Sumayah , Pozzi Federico , Raisis Leo
Published: March 2014

Objective

Performance tests and self‐reported questionnaires capture different domains of function in patients with lower extremity osteoarthritis, but the impairments related to each of these domains have not been elucidated. The purpose of this study was to determine how strength and joint pain influence performance‐based tests and self‐reported questionnaires of functional ability of individuals with end‐stage hip osteoarthritis.

Methods

Fifty‐six patients scheduled to undergo unilateral total hip arthroplasty were included in this cross‐sectional analysis. Subjects completed the Hip Outcome Survey (HOS) and pain in the affected hip was quantified on a scale from 0–10. Performance‐based tests included the Six‐Minute Walk Test (6MWT), the Timed Up & Go (TUG), and the Stair Climbing Test (SCT). Isometric strength of the hip abductors and knee extensors was tested and recorded. Hierarchical linear regressions were created to determine the contributions of pain, knee extensor strength, and hip strength for each outcome measure (TUG, 6MWT, SCT, and HOS). Height and body mass index were entered first, followed by pain, then knee extensor strength, and then hip abduction strength.

Results

Greater pain significantly predicted lower HOS scores, but hip strength did not significantly improve the model. Hip pain was also significantly related to TUG, SCT, and 6MWT values, but hip and knee strength explained additional variance for these performance‐based measures.

Conclusion

Self‐report and performance‐based measures capture different aspects of disability and are influenced by different underlying impairments. Both types of outcome measures should be used in studies that evaluate functional changes in patients with hip osteoarthritis.
Effect of SLM Parameters on Transformation Temperatures of Shape Memory Nickel Titanium Parts
Authors: Dadbakhsh Sasan , Speirs Mathew , Kruth Jean‐Pierre , Schrooten Jan , Luyten Jan , Van Humbeeck Jan
Published: March 2014

Selective laser melting (SLM) is used to manufacture dense nickel titanium (NiTi) parts. The reversible martensitic transformation of the NiTi parts is investigated with various SLM parameters. The parameters are in the same energy density range, composed of high laser parameters (HP: high laser power adjusted to high scanning speed) and low laser parameters (LP: low laser power adjusted to low scanning speed). The results are linked to the mechanical behavior and shape memory response achieved from compression and dilatometry tests. It is shown that the products may exhibit distinct transformation temperatures depending on the used SLM parameters. The atomized powders and the HP SLM parts with dominant pseudoelastic properties contain austenite at room temperature (due to their lower transformation temperatures), in contrast to the large thermal memory of the LP parts originating from martensitic phases (corresponding to higher transformation temperatures). The post‐annealed samples undergo transformations in a comparable temperature range, implying no significant effect of SLM on composition of the originally used powder. The possible origin of the above findings is postulated and discussed.
Domain Compositions and Fullerene Aggregation Govern Charge Photogeneration in Polymer/Fullerene Solar Cells
Authors: Kesava Sameer Vajjala , Fei Zhuping , Rimshaw Adam D. , Wang Cheng , Hexemer Alexander , Asbury John B. , Heeney Martin , Gomez Enrique D.
Published: March 2014

The complex microstructure of organic semiconductor mixtures continues to obscure the connection between the active layer morphology and photovoltaic device performance. For example, the ubiquitous presence of mixed phases in the active layer of polymer/fullerene solar cells creates multiple morphologically distinct interfaces which are capable of exciton dissociation or charge recombination. Here, it is shown that domain compositions and fullerene aggregation can strongly modulate charge photogeneration at ultrafast timescales through studies of a model system, mixtures of a low band‐gap polymer, poly[(4,4′‐bis(2‐ethylhexyl)dithieno[3,2‐b:2′,3′‐d]germole)‐2,6‐diyl‐alt‐(2,1,3‐benzothia‐diazole)‐4,7‐diyl], and [6,6]‐phenyl‐C71‐butyric acid methyl ester. Structural characterization using energy‐filtered transmission electron microscopy (EFTEM) and resonant soft X‐ray scattering shows similar microstructures even with changes in the overall film composition. Composition maps generated from EFTEM, however, demonstrate that compositions of mixed domains vary significantly with overall film composition. Furthermore, the amount of polymer in the mixed domains is inversely correlated with device performance. Photoinduced absorption studies using ultrafast infrared spectroscopy demonstrate that polaron concentrations are highest when mixed domains contain the least polymer. Grazing‐incidence X‐ray scattering results show that larger fullerene coherence lengths are correlated to higher polaron yields. Thus, the purity of the mixed domains is critical for efficient charge photogeneration because purity modulates fullerene aggregation and electron delocalization.
Multiscale modeling for surface composition of spray‐dried two‐component powders
Authors: Xiao Jie , Chen Xiao Dong
Published: March 2014

Spray drying is a primary process for manufacturing various powder products. One of the most important properties of powders is the ability to get wet. Surface chemical composition critically influences this property. Furthermore, surface composition also influences the efficiency of production as it affects the stickiness of the powder. This work is an attempt to analyze the surface compositions of spray‐dried two‐component powders produced under various conditions using an innovative multiscale modeling approach. A molecular‐level geometrical interpretation is seamlessly coupled with a continuum diffusion model. The predictions are compared with the measurements done on the protein–lactose system using X‐ray photoelectron spectroscopy. Sample calculations for the system have demonstrated that the new approach helps reveal surface formation mechanisms much better than that explained with the monoscale continuum approach. This work provides a good basis for a fruitful area of study toward surface composition‐focused powder quality control that will have a positive impact in industries. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2416–2427, 2014
Multiple congenital anomalies‐intellectual disability (MCA‐ID) and neuroblastoma in a patient harboring a de novo 14q23.1q23.3 deletion
Authors: Lehalle Daphné , Sanlaville Damien , Guimier Anne , Plouvier Emmanuel , Leblanc Thierry , Galmiche Louise , Radford Isabelle , Romana Serge , Colleaux Laurence , de Pontual Loïc , Lyonnet Stanislas , Amiel Jeanne
Published: March 2014

Neuroblastoma is the most frequent extra cranial solid tumor in infants and children. Genetic predisposition to neuroblastoma has been suspected previously due to familial cases of sporadic NB and predisposition to NB in several syndromes. Here, we report on a de novo 14q23.1–q23.3 microdeletion in a male presenting with a neuroblastoma diagnosed at 9 months, and spherocytosis, congenital heart defect, cryptorchidism, hypoplasia of corpus callosum, epilepsy, and developmental delay. Myc‐associated‐factor X (MAX) haploinsufficiency could be regarded as the predisposing factor to NB. Indeed 14q deletion is a recurrent somatic rearrangement in NB and MAX somatic and germline loss of function mutation have recently been described in pheochromocytoma and paraganglioma. However, MAX was expressed in the tumor of the patient we report on and, accordingly, loss of heterozygosity, mutation, or promoter methylation were excluded. In addition, we discuss the potential involvement in the clinical spectrum presented by the patient of five of the deleted genes, namely DAAM1, PLEKHG3, SPTB, AKAP5, and ARID4A. © 2014 Wiley Periodicals, Inc.
Genetic counselor review of genetic test orders in a reference laboratory reduces unnecessary testing
Authors: Miller Christine E. , Krautscheid Patti , Baldwin Erin E. , Tvrdik Tatiana , Openshaw Amanda S. , Hart Kim , LaGrave Danielle
Published: March 2014

Genetic tests are routinely ordered by health care providers (HCPs) within a wide range of medical specialties. Many providers have limited knowledge or experience with ordering and interpreting genetic tests; thus, test order errors are common. Rigorous review of genetic test orders by genetic counselors (GCs) can provide a direct financial benefit to medical institutions, patients and insurers. GCs at ARUP (Associated Regional University Pathologists) Laboratories routinely perform a preanalytic assessment of complex molecular genetic test orders that includes reviewing clinical and family history information and considering the clinical utility and cost‐effectiveness of ordered tests. GCs contact the ordering institution and/or HCP as needed to collect additional clinical information and confirm the test order or suggest alternative testing based on the provided information. A retrospective review of the GC‐facilitated test changes over a 21‐month period at ARUP laboratories was performed. Approximately 26% of all requests for complex genetic tests assessing germ line mutations were changed following GC review. Testing fees associated with canceled tests were summed to estimate the cost‐savings resulting from GC‐facilitated test reviews. The test review process resulted in an average reduction in charges to the referring institutions of $48,000.00 per month. GC review of genetic test orders for appropriateness and clinical utility reduces healthcare costs to hospitals, insurers, and patients. © 2014 Wiley Periodicals, Inc.
Cervical spine malformation in cornelia de lange syndrome: A report of three patients
Authors: Bettini Laura Rachele , Locatelli Laura , Mariani Milena , Cianci Paola , Giussani Carlo , Canonico Francesco , Cereda Anna , Russo Silvia , Gervasini Cristina , Biondi Andrea , Selicorni Angelo
Published: March 2014

Cornelia de Lange syndrome (CdLS) is a complex genetic disease with skeletal involvement mostly related to upper limb malformations. We report on three males with clinical and molecular diagnoses of CdLS. Besides typical CdLS features, all showed different cervical spine malformations. To the best of our knowledge, this is an unusual malformation in the CdLS phenotypic spectrum. © 2014 Wiley Periodicals, Inc.
Relationship between whole‐body tumor burden, clinical phenotype, and quality of life in patients with neurofibromatosis
Authors: Merker Vanessa L. , Bredella Miriam A. , Cai Wenli , Kassarjian Ara , Harris Gordon J. , Muzikansky Alona , Nguyen Rosa , Mautner Victor F. , Plotkin Scott R.
Published: March 2014

Patients with neurofibromatosis 1 (NF1), NF2, and schwannomatosis share a predisposition to develop multiple nerve sheath tumors. Previous studies have demonstrated that patients with NF1 and NF2 have reduced quality of life (QOL), but no studies have examined the relationship between whole‐body tumor burden and QOL in these patients. We administered a QOL questionnaire (the SF‐36) and a visual analog pain scale (VAS) to a previously described cohort of adult neurofibromatosis patients undergoing whole‐body MRI. One‐sample t‐tests were used to compare norm‐based SF‐36 scores to weighted population means. Spearman correlation coefficients and multiple linear regression analyses controlling for demographic and disease‐specific clinical variable were used to relate whole‐body tumor volume to QOL scales. Two hundred forty‐five patients (142 NF1, 53 NF2, 50 schwannomatosis) completed the study. Subjects showed deficits in selected subscales of the SF‐36 compared to adjusted general population means. In bivariate analysis, increased tumor volume was significantly associated with pain in schwannomatosis patients, as measured by the SF‐36 bodily pain subscale (rho = −0.287, P = 0.04) and VAS (rho = 0.34, P = 0.02). Regression models for NF2 patients showed a positive relationship between tumor burden and increased pain, as measured by the SF‐36 (P = 0.008). Patients with NF1, NF2, and schwannomatosis suffer from reduced QOL, although only pain shows a clear relationship to patient's overall tumor burden. These findings suggest that internal tumor volume is not a primary contributor to QOL and emphasize the need for comprehensive treatment approaches that go beyond tumor‐focused therapies such as surgery by including psychosocial interventions. © 2014 Wiley Periodicals, Inc.
Further delineation of eye manifestations in homozygous 15q13.3 microdeletions including TRPM1: A differential diagnosis of ceroid lipofuscinosis
Authors: Masurel‐Paulet Alice , Drumare Isabelle , Holder Muriel , Cuisset Jean‐Marie , Vallée Louis , Defoort Sabine , Bourgois Béatrice , Pernes Philippe , Cuvellier Jean‐Christophe , Huet Frédéric , Chehadeh Salima El , Thevenon Julien , Callier Patrick , Thauvin Christel , Faivre Laurence , Andrieux Joris
Published: March 2014

The 15q13.3 heterozygous microdeletion is a fairly common microdeletion syndrome with marked clinical variability and incomplete penetrance. The average size of the deletion, which comprises six genes including CHRNA7, is 1.5 Mb. CHRNA7 has been identified as the gene responsible for the neurological phenotype in this microdeletion syndrome. Only seven patients with a homozygous microdeletion that includes at least CHRNA7, and is inherited from both parents have been described in the literature. The aim of this study was to further describe the distinctive eye manifestations from the analysis in the three French patients diagnosed with the classical 1.5 Mb homozygous microdeletion. Patients' ages ranged from 30 months to 9 years, and included one sib pair. They all displayed a remarkably severe identifiable clinical phenotype that included congenital blindness and convulsive encephalopathy with inconstant abnormal movements. The ophthalmological examination revealed a lack of eye tracking, optic nerve pallor, an immature response with increased latencies with no response to the checkerboard stimulations at the visual evoked potential examination, and a distinctive retina dystrophy with a negative electroretinogram in which the “b” wave was smaller than the “a” wave after a dark adapted pupil and bright flash in all patients. Clear genotype–phenotype correlations emerged, showing that this eye phenotype was secondary to homozygous deletion of TRPM1, the gene responsible for autosomal recessive congenital stationary night blindness. The main differential diagnosis is ceroid lipofuscinosis. © 2014 Wiley Periodicals, Inc.
Maternal smoking, xenobiotic metabolizing enzyme gene variants, and gastroschisis risk
Authors: Jenkins Mary M. , Reefhuis Jennita , Gallagher Margaret L. , Mulle Jennifer G. , Hoffmann Thomas J. , Koontz Deborah A. , Sturchio Cynthia , Rasmussen Sonja A. , Witte John S. , Richter Patricia , Honein Margaret A. ,   the National Birth Defects Prevention Study
Published: March 2014

Maternal smoking during pregnancy is one proposed risk factor for gastroschisis, but reported associations have been modest, suggesting that differences in genetic susceptibility might play a role. We included 108 non‐Hispanic white and 62 Hispanic families who had infants with gastroschisis, and 1,147 non‐Hispanic white and 337 Hispanic families who had liveborn infants with no major structural birth defects (controls) in these analyses. DNA was extracted from buccal cells collected from infants and mothers, and information on periconceptional smoking history was obtained from maternal interviews, as part of the National Birth Defects Prevention Study. We analyzed five polymorphisms in three genes that code for enzymes involved in metabolism of some cigarette smoke constituents (CYP1A1, CYP1A2, and NAT2). Logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) independently for maternal smoking and maternal and infant gene variants, and to assess joint associations of maternal smoking and maternal or infant gene variants with gastroschisis. In analyses adjusted for maternal age at delivery and stratified by maternal race‐ethnicity, we identified three suggestive associations among 30 potential associations with sufficient numbers to calculate ORs: CYP1A1*2A for non‐Hispanic white mothers who smoked periconceptionally (aOR = 0.38, 95% CI 0.15–0.98), and NAT2*6 for Hispanic non‐smoking mothers (aOR = 2.17, 95% CI 1.12–4.19) and their infants (aOR = 2.11, 95% CI 1.00–4.48). This analysis does not support the occurrence of effect modification between periconceptional maternal smoking and most of the xenobiotic metabolizing enzyme gene variants assessed. © 2014 Wiley Periodicals, Inc.
Asymmetric Michael Reaction of Nitroolefins with β‐Dicarbonyl Compounds Catalysed by 1,3‐Diamine‐Tethered Guanidine‐Thiourea Bifunctional Organocatalysts
Authors: Horitsugi Natsuko , Kojima Kohei , Yasui Koji , Sohtome Yoshihiro , Nagasawa Kazuo
Published: March 2014

The enantioselective Michael reaction of β‐dicarbonyl compounds with nitroolefins was achieved by using guanidine/bisthiourea bifunctional organocatalysts in which the functional groups are linked by a 1,3‐diamine moiety. Aromatic and aliphatic nitroolefins are compatible with both acyclic and cyclic β‐dicarbonyl compounds to afford the corresponding Michael adducts in yields of up to 99 % and enantioselectivity of up to 95 % ee.
Characteristics of venom allergic reactions in Turkish beekeepers and alternative treatment modalities
Authors: Çelıksoy Mehmet Halil , Sancak Recep , Söğüt Ayhan , Güner Şükrü Nail , Korkmaz Ali
Published: March 2014

Background

The objective of this work was to determine the characteristics of allergic reactions that may occur after a bee sting and alternative treatment methods in Turkish beekeepers.

Methods

A written questionnaire was administered to beekeepers from the Ordu, Samsun, Sinop, Amasya, and Çorum provinces located in the Central Black Sea Region of Turkey.

Results

The study included 301 beekeepers, 295 (98%) of whom were male. Their mean age was 48.2 ± 11.5 years. The mean beekeeping duration was 15.3 ± 10.5 years. A total of 270 participants (89.9%) had a history of bee stings in the previous 12 months. Systemic reactions, large local reactions, and local reactions were seen in 21 (6.9%), 193 (64.1%), and 12 (4.0%) beekeepers, respectively. The face was the most frequently stung body site, and swelling generally occurred in the eyelids. The size of the swellings decreased within 12 to 24 hours in 259 (86.1%) beekeepers. The size of the swellings was 1 × 2 cm in diameter in 157 (52.2%) beekeepers. Natural protection against bee stings had developed by 12 months in 140 (46.5%) beekeepers. In total, 61.5% of the beekeepers applied alternative treatments (eg, garlic, onion water, yogurt), whereas 14.0% (3/21) were admitted to a hospital with a systemic reaction. In total, 10.6% and 14.2% of beekeepers were aware of adrenaline auto‐injector and venom immunotherapy, respectively.

Conclusion

This study indicates insufficient knowledge and attitudes among Turkish beekeepers regarding bee sting reactions.
What is normal nasal airflow? A computational study of 22 healthy adults
Authors: Zhao Kai , Jiang Jianbo
Published: March 2014

Background

Nasal airflow is essential for the functioning of the human nose. Given individual variation in nasal anatomy, there is yet no consensus what constitutes normal nasal airflow patterns. We attempt to obtain such information that is essential to differentiate disease‐related conditions.

Methods

Computational fluid dynamics (CFD) simulated nasal airflow in 22 healthy subjects during resting breathing. Streamline patterns, airflow distributions, velocity profiles, pressure, wall stress, turbulence, and vortical flow characteristics under quasi–steady state were analyzed. Patency ratings, acoustically measured minimum cross‐sectional area (MCA), and rhinomanometric nasal resistance (NR) were examined for potential correlations with morphological and airflow‐related variables.

Results

Common features across subjects included: >50% total pressure drop reached near the inferior turbinate head; wall shear stress, NR, turbulence energy, and vorticity were lower in the turbinate than in the nasal valve region. However, location of the major flow path and coronal velocity distributions varied greatly across individuals. Surprisingly, on average, more flow passed through the middle than the inferior meatus and correlated with better patency ratings (r = −0.65, p < 0.01). This middle flow percentage combined with peak postvestibule nasal heat loss and MCA accounted for >70% of the variance in subjective patency ratings and predicted patency categories with 86% success. Nasal index correlated with forming of the anterior dorsal vortex. Expected for resting breathing, the functional impact for local and total turbulence, vorticity, and helicity was limited. As validation, rhinomanometric NR significantly correlated with CFD simulations (r = 0.53, p < 0.01).

Conclusion

Significant variations of nasal airflow found among healthy subjects; Key features may have clinically relevant applications.
Crista galli mucocele: endoscopic marsupialization via frontoethmoid approach
Authors: Cervantes Sergio Santino , Lal Devyani
Published: March 2014

Background

We report the first report of an expansile crista galli (CG) mucocele treated surgically by an endoscopic endonasal approach. Only 1 other case of a CG mucocele has been previously reported in the literature. This was treated by a craniotomy approach.

Case Report

We describe the technique employed in endoscopic marsupialization. We also discuss relevant CG anatomy, pneumatization patterns, surgical approaches, and its potential to cause disease, including CG sinusitis and mucocele formation.

Conclusion

We present this case to highlight that the growing experience with endoscopic techniques offer us less morbid and more functional alternatives to a variety of lesions that were once tackled by neurosurgical or external approaches. In the contemporary era, the indications for open approaches and craniotomy for frontal sinus and CG lesions is likely limited. We recommend these patients undergo careful evaluation by a surgeon experienced in advanced endoscopic techniques before being advised to undergo open or craniotomy techniques.
Coaxing Solid‐State Phosphorescence from Tellurophenes
Authors: He Gang , Torres Delgado William , Schatz Devon J. , Merten Christian , Mohammadpour Arash , Mayr Lorenz , Ferguson Michael J. , McDonald Robert , Brown Alex , Shankar Karthik , Rivard Eric
Published: March 2014

The synthesis of the first examples of tellurophenes exhibiting phosphorescence in the solid state and under ambient conditions (room temperature and in air) is reported. Each of these main‐group‐element‐based emitters feature pinacolboronates (BPin) as ring‐appended side groups. The nature of the luminescence observed was also investigated using computational methods.
Point Decoration of Silicon Nanowires: An Approach Toward Single‐Molecule Electrical Detection
Authors: Wang Jindong , Shen Fangxia , Wang Zhenxing , He Gen , Qin Jinwen , Cheng Nongyi , Yao Maosheng , Li Lidong , Guo Xuefeng
Published: March 2014

Probing interactions of biological systems at the molecular level is of great importance to fundamental biology, diagnosis, and drug discovery. A rational bioassay design of lithographically integrating individual point scattering sites into electrical circuits is capable of realizing real‐time, label‐free biodetection of influenza H1N1 viruses with single‐molecule sensitivity and high selectivity by using silicon nanowires as local reporters in combination with microfluidics. This nanocircuit‐based architecture is complementary to more conventional optical techniques, but has the advantages of no bleaching problems and no fluorescent labeling. These advantages offer a promising platform for exploring dynamics of stochastic processes in biological systems and gaining information from genomics to proteomics to improve accurate molecular and even point‐of‐care clinical diagnosis.
Silver(I)‐Catalyzed Hydroazidation of Ethynyl Carbinols: Synthesis of 2‐Azidoallyl Alcohols
Authors: Liu Zhenhua , Liu Jianquan , Zhang Lin , Liao Peiqiu , Song Jinna , Bi Xihe
Published: March 2014

The hydroazidation of alkynes is the most straightforward pathway to synthetically useful vinyl azides. However, a general hydroazidation of alkynes remains elusive. Herein, a chemo‐ and regioselective transformation of ethynyl carbinols into vinyl azides is described. This reaction produces a wide variety of 2‐azidoallyl alcohols with high efficiency and in good to excellent yields. These compounds constitute a new class of densely functionalized synthetic intermediates. Their synthetic potential has been demonstrated by further transformations into NH aziridines. The mechanistic aspects of the reaction will attract the attention of chemists working on alkyne chemistry and silver catalysis. The findings that are described in this paper represent significant advances in the regioselective hydroelementation of alkynes and open a new reaction manifold for exploitation.
Total Chemical Synthesis of the Enzyme Sortase AΔN59 with Full Catalytic Activity
Authors: Deng Fang‐Kun , Zhang Liang , Wang Ya‐Ting , Schneewind Olaf , Kent Stephen B. H.
Published: March 2014

The enzyme sortase A is a ligase which catalyzes transpeptidation reactions.1, 2 Surface proteins, including virulence factors, that have a C terminal recognition sequence are attached to Gly5 on the peptidoglycan of bacterial cell walls by sortase A.1 The enzyme is an important anti‐virulence and anti‐infective drug target for resistant strains of Gram‐positive bacteria.2 In addition, because sortase A enables the splicing of polypeptide chains, the transpeptidation reaction catalyzed by sortase A is a potentially valuable tool for protein science.3 Here we describe the total chemical synthesis of enzymatically active sortase A. The target 148 residue polypeptide chain of sortase AΔN59 was synthesized by the convergent chemical ligation of four unprotected synthetic peptide segments. The folded protein molecule was isolated by size‐exclusion chromatography and had full enzymatic activity in a transpeptidation assay. Total synthesis of sortase A will enable more sophisticated engineering of this important enzyme molecule.
Catalytic Transfer Hydrogenation by a Trivalent Phosphorus Compound: Phosphorus‐Ligand Cooperation Pathway or PIII/PV Redox Pathway?
Authors: Zeng Guixiang , Maeda Satoshi , Taketsugu Tetsuya , Sakaki Shigeyoshi
Published: March 2014

Main‐group‐element catalysts are a desirable alternative to transition‐metal catalysts because of natural abundance and cost. However, the examples are very limited. Catalytic cycles involving a redox process and E‐ligand cooperation (E=main‐group element), which are often found in catalytic cycles of transition‐metal catalysts, have not been reported. Herein theoretical investigations of a catalytic hydrogenation of azobenzene with ammonia–borane using a trivalent phosphorus compound, which was experimentally proposed to occur through PIII/PV redox processes via an unusual pentavalent dihydridophosphorane, were performed. DFT and ONIOM(CCSD(T):MP2) calculations disclosed that this catalytic reaction occurs through a P‐O cooperation mechanism, which resembles the metal‐ligand cooperation mechanism of transition‐metal catalysts.
Catalytic Asymmetric Synthesis of [2,3]‐Fused Indoline Heterocycles through Inverse‐Electron‐Demand Aza‐Diels–Alder Reaction of Indoles with Azoalkenes
Authors: Tong Min‐Chao , Chen Xuan , Li Jun , Huang Rong , Tao Haiyan , Wang Chun‐Jiang
Published: March 2014

An unprecedented catalytic asymmetric inverse‐electron‐demand aza‐Diels–Alder reaction of indoles with in situ formed azoalkenes is reported. A diverse set of [2,3]‐fused indoline heterocycles were achieved in generally good yields (up to 97 %) with high regioselectivity and diastereoselectivity (>20:1 d.r.), and with excellent enantioselectivity (up to 99 % ee).
Bidirektionale Chemische Kommunikation zwischen nanomechanischen Schaltern
Authors: Pramanik Susnata , De Soumen , Schmittel Michael
Published: March 2014

Das Zusammenspiel zwischen biologischen Systemen hängt entscheidend von der Bidirektionalität des chemischen Informationsaustauschs ab. Die Implementierung eines derartigen Kommunikationsprotokolls für abiologische Systeme gelingt unter Nutzung von zwei Nanoschaltern, die beide unter Übertragung von Kupferionen in den Oxidationsstufen +I und +II jeweils als Empfänger und Sender eingesetzt werden können. Selbst bei mikromolaren Konzentrationen verläuft die Kommunikation in beide Richtungen mit t1/2=2–3 min beachtlich schnell. Die Metallionenübertragung löst einen Schwenk des Dreharms um 20 Å an beiden Schaltern und damit beachtliche geometrische und elektronische Veränderungen aus.
Rate Coefficients of C1 and C2 Criegee Intermediate Reactions with Formic and Acetic Acid Near the Collision Limit: Direct Kinetics Measurements and Atmospheric Implications
Authors: Welz Oliver , Eskola Arkke J. , Sheps Leonid , Rotavera Brandon , Savee John D. , Scheer Adam M. , Osborn David L. , Lowe Douglas , Murray Booth A. , Xiao Ping , Anwar H. Khan M. , Percival Carl J. , Shallcross Dudley E. , Taatjes Craig A.
Published: March 2014

Rate coefficients are directly determined for the reactions of the Criegee intermediates (CI) CH2OO and CH3CHOO with the two simplest carboxylic acids, formic acid (HCOOH) and acetic acid (CH3COOH), employing two complementary techniques: multiplexed photoionization mass spectrometry and cavity‐enhanced broadband ultraviolet absorption spectroscopy. The measured rate coefficients are in excess of 1×10−10 cm3 s−1, several orders of magnitude larger than those suggested from many previous alkene ozonolysis experiments and assumed in atmospheric modeling studies. These results suggest that the reaction with carboxylic acids is a substantially more important loss process for CIs than is presently assumed. Implementing these rate coefficients in global atmospheric models shows that reactions between CI and organic acids make a substantial contribution to removal of these acids in terrestrial equatorial areas and in other regions where high CI concentrations occur such as high northern latitudes, and implies that sources of acids in these areas are larger than previously recognized.
Metal‐Free Photochemical Aromatic Perfluoroalkylation of α‐Cyano Arylacetates
Authors: Nappi Manuel , Bergonzini Giulia , Melchiorre Paolo
Published: March 2014

We report here an operationally simple protocol for the direct aromatic perfluoroalkylation and trifluoromethylation of α‐cyano arylacetates. This metal‐free approach, which occurs at ambient temperature and under visible‐light irradiation, is driven by the photochemical activity of electron donor–acceptor (EDA) complexes, formed in situ by the interaction of transiently generated enolates and perfluoroalkyl iodides. Preliminary mechanistic studies are reported.
Gas‐Phase Synthesis of the Benzyl Radical (C6H5CH2)
Authors: Dangi Beni B. , Parker Dorian S. N. , Yang Tao , Kaiser Ralf I. , Mebel Alexander M.
Published: March 2014

Dicarbon (C2), the simplest bare carbon molecule, is ubiquitous in the interstellar medium and in combustion flames. A gas‐phase synthesis is presented of the benzyl radical (C6H5CH2) by the crossed molecular beam reaction of dicarbon, C2(X1Σg+, a3Πu), with 2‐methyl‐1,3‐butadiene (isoprene; C5H8; X1A′) accessing the triplet and singlet C7H8 potential energy surfaces (PESs) under single collision conditions. The experimental data combined with ab initio and statistical calculations reveal the underlying reaction mechanism and chemical dynamics. On the singlet and triplet surfaces, the reactions involve indirect scattering dynamics and are initiated by the barrierless addition of dicarbon to the carbon–carbon double bond of the 2‐methyl‐1,3‐butadiene molecule. These initial addition complexes rearrange via multiple isomerization steps, leading eventually to the formation of C7H7 radical species through atomic hydrogen elimination. The benzyl radical (C6H5CH2), the thermodynamically most stable C7H7 isomer, is determined as the major product.
Balancing the Rate of Cluster Growth and Etching for Gram‐Scale Synthesis of Thiolate‐Protected Au25 Nanoclusters with Atomic Precision
Authors: Yuan Xun , Zhang Bin , Luo Zhentao , Yao Qiaofeng , Leong David Tai , Yan Ning , Xie Jianping
Published: March 2014

We report a NaOH‐mediated NaBH4 reduction method for the synthesis of mono‐, bi‐, and tri‐thiolate‐protected Au25 nanoclusters (NCs) with precise control of both the Au core and thiolate ligand surface. The key strategy is to use NaOH to tune the formation kinetics of Au NCs, i.e., reduce the reduction ability of NaBH4 and accelerate the etching ability of free thiolate ligands, leading to a well‐balanced reversible reaction for rapid formation of thermodynamically favorable Au25 NCs. This protocol is facile, rapid (≤3 h), versatile (applicable for various thiolate ligands), and highly scalable (>1 g Au NCs). In addition, bi‐ and tri‐thiolate‐protected Au25 NCs with adjustable ratios of hetero‐thiolate ligands were easily obtained. Such ligand precision in molecular ratios, spatial distribution and uniformity resulted in richly diverse surface landscapes on the Au NCs consisting of multiple functional groups such as carboxyl, amine, and hydroxy. Analysis based on NMR spectroscopy revealed that the hetero‐ligands on the NCs are well distributed with no ligand segregation. The unprecedented synthesis of multi‐thiolate‐protected Au25 NCs may further promote the practical applications of functional metal NCs.
Real‐Time In Vivo Quantitative Monitoring of Drug Release by Dual‐Mode Magnetic Resonance and Upconverted Luminescence Imaging
Authors: Liu Jianan , Bu Jiwen , Bu Wenbo , Zhang Shengjian , Pan Limin , Fan Wenpei , Chen Feng , Zhou Liangpin , Peng Weijun , Zhao Kuaile , Du Jiulin , Shi Jianlin
Published: March 2014

Insufficient or excess drug doses, due to unknown actual drug concentrations at the focus, are one of the main causes of chemotherapy failure for cancers. In this regard, the real‐time monitoring of the release of anticancer drugs from nanoparticle drug delivery systems is of crucial importance, but it remains a critical and unsolved challenge. Herein, we report the proposal and development of a novel concept of real‐time monitoring of NIR‐triggered drug release in vitro and in vivo by using simultaneous upconverted luminescence (UCL) and magnetic resonance (MR) imaging. Such a monitoring strategy features the high sensitivity of UCL and the high‐resolution, noninvasiveness, and tissue‐depth‐independence of MR imaging. The dual‐mode real‐time and quantitative monitoring of drug release can be applied to determine online the drug concentrations in vivo in the tissue regions of interest and, therefore, to avoid insufficient or excess drug dosings.
In Vivo Chemoembolization and Magnetic Resonance Imaging of Liver Tumors by Using Iron Oxide Nanoshell/Doxorubicin/Poly(vinyl alcohol) Hybrid Composites
Authors: Wang Yi‐Xiang J. , Zhu Xiao‐Ming , Liang Qi , Cheng Christopher H. K. , Wang Wei , Leung Ken Cham‐Fai
Published: March 2014

A hybrid composite made up of superparamagnetic iron oxide nanoshells encapsulating the anticancer drug doxorubicin and bound together by poly(vinyl alcohol) was developed. Transcatheter arterial delivery in an in vivo liver tumor model led to embolization of the liver tumor blood vessels. Embolization was followed by disassembly of the composite. The nanoshells were then able to pass through the leaky tumor vasculature into the tumor tissue, thereby leading to slow and sustained release of the drug. As well as being relatively noncytotoxic, the composite was responsive to magnetic resonance imaging, thus making it a potentially useful theranostic agent.
Synthesis of Cyano‐Substituted Diaryltetracenes from Tetraaryl[3]cumulenes
Authors: Gawel Przemyslaw , Dengiz Cagatay , Finke Aaron D. , Trapp Nils , Boudon Corinne , Gisselbrecht Jean‐Paul , Diederich François
Published: March 2014

A versatile, two‐step synthesis of highly substituted, cyano‐functionalized diaryltetracenes has been developed, starting from easily accessible tetraaryl[3]cumulenes. This unprecedented transformation is initiated by [2+2] cycloaddition of tetracyanoethylene (TCNE) to the proacetylenic central double bond of the cumulenes to give an intermediate zwitterion, which after an electrocyclization cascade and dehydrogenation yields 5,5,11,11‐tetracyano‐5,11‐dihydrotetracenes in a one‐pot procedure. A subsequent copper‐assisted decyanation/aromatization provided the target 5,11‐dicyano‐6,12‐diaryltetracene derivatives. All of the postulated structures were confirmed by X‐ray crystallography. The new chromophores are thermally highly stable and feature promising fluorescence properties for potential use in optoelectronic devices. They are selective chemosensors for CuI ions, which coordinate to one of the CN substituents and form a 1:1 complex with an association constant of Ka=1.5×105 L mol−1 at 298 K.
Comparison of amine solutions performance for gas sweetening
Authors: Abkhiz Vahid , Heydari Isa
Published: March 2014

Using different kinds of amines, in Fajr‐e‐Jam gas refinery, including mixed or activated amines, have provided the chance for better analysis of different kinds of amines performance. In the current work, the most important parameters in gas sweetening refineries such as amine circulation rate, steam consumption, CO2 and mercaptan removal were investigated for sweetening trains utilizing diethanolamine (DEA), methyldiethanolamine (MDEA), DEA/MDEA and activated methyldiethanolamine (aMDEA). In the case of steam consumption and circulation rates, MDEA and aMDEA, show the less required rates to meet lean amine loadings. For CO2 removal aMDEA has the best efficiency. In the case of mercaptan removal, DEA shows the best absorption rate compared with other three amines. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd.
Effect of acrylonitrile–butadiene–styrene on flow behavior and mechanical properties of polylactic acid/low density polyethylene blend
Authors: Hamad Kotiba , Ko Young Gun , Kaseem Mosab , Deri Fawaz
Published: March 2014

The influence of acrylonitrile–butadiene–styrene (ABS) copolymer content on the properties of polylactic acid (PLA)/low density polyethylene (LDPE) blend (50/50) was investigated in the present paper. The blend (PLA/LDPE/ABS) was prepared in different ratios using a laboratory scale single screw extruder. The prepared blends were characterized in terms of rheological and mechanical properties. Rheological properties were studied using a capillary rheometer, and the Bagley's correction was performed. Shear rate (γr), shear stress (τr), shear viscosity (ηr), and non‐Newtonian index (n) were determined. The relationship between shear viscosity and temperature was also studied, and the flow activation energy at a constant shear rate (Eγ) was determined. The mechanical properties of the blends were investigated on dog‐bone‐shaped samples obtained by an injection molding machine. The tensile tests were performed using Testometric M350‐10KN, and the stress at break, strain at break, and Young's modulus were determined. Rheological properties revealed that the blend exhibited shear‐thinning behavior over the range of the studied shear rates, and the viscosity of the blend increased as the ABS content increased, whereas the flow activation energy decreased. Based on the mechanical properties determined for the prepared blends, it was found that no relation between ABS content and stress at break of the blend was regarded, whereas Young's modulus was significantly improved by the addition of ABS. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd.
Dry and wet mechanical properties of polylactic acid in the presence of canola oil
Authors: Kumar Rakesh , Josse Camille , Anandjiwala Rajesh
Published: March 2014

Polylactic acid (PLA) is a compostable and biodegradable polymer obtained from renewable resources. They can be used in the packaging and medical industries. For our study, two grades of PLA resins were procured. One grade was procured from Cereplast, Inc., USA, (CPL) and other from NatureWorks LLC, USA, (NWPL). Mechanical, thermal, thermomechanical and morphological studies were carried out for PLA resins procured from both the sources. Virgin and modified canola oil (0.25–0.5% with respect to PLA) were mixed manually with CPL and NWPL to prepare injection‐moulded specimens. Mechanical, thermal, thermomechanical and morphological studies of injection moulded PLA samples in the presence of canola oil were then carried out. Results indicated that canola oil acted as a plasticizer for PLA specimens. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd.
Ultrafast Dynamics of Solvation and Charge Transfer in a DNA‐Based Biomaterial
Authors: Choudhury Susobhan , Batabyal Subrata , Mondol Tanumoy , Sao Dilip , Lemmens Peter , Pal Samir Kumar
Published: March 2014

Charge migration along DNA molecules is a key factor for DNA‐based devices in optoelectronics and biotechnology. The association of a significant amount of water molecules in DNA‐based materials for the intactness of the DNA structure and their dynamic role in the charge‐transfer (CT) dynamics is less documented in contemporary literature. In the present study, we have used a genomic DNA–cetyltrimethyl ammonium chloride (CTMA) complex, a technological important biomaterial, and Hoechest 33258 (H258), a well‐known DNA minor groove binder, as fluorogenic probe for the dynamic solvation studies. The CT dynamics of CdSe/ZnS quantum dots (QDs; 5.2 nm) embedded in the as‐prepared and swollen biomaterial have also been studied and correlated with that of the timescale of solvation. We have extended our studies on the temperature‐dependent CT dynamics of QDs in a nanoenvironment of an anionic, sodium bis(2‐ethylhexyl)sulfosuccinate reverse micelle (AOT RMs), whereby the number of water molecules and their dynamics can be tuned in a controlled manner. A direct correlation of the dynamics of solvation and that of the CT in the nanoenvironments clearly suggests that the hydration barrier within the Arrhenius framework essentially dictates the charge‐transfer dynamics.
Creativity and education: comparing the national curricula of the states of the European Union and the United Kingdom
Authors: Wyse Dominic , Ferrari Anusca
Published: March 2014

In the past 20 years the importance of creativity as part of young people's education has increasingly been recognised. The stimulus for the growing emphasis on creativity has come from diverse sources including drives for greater national economic prosperity and enlightenment visions of young people's education. One facet of creativity in education has been its place in the national curriculum texts of nation states. The research reported in this paper aimed to investigate the place of creativity in the national curricula of the 27 member states of theEU(EU27) and in theUK. A content analysis of all statutory national curriculum texts for theEU27 was undertaken and implications compared to the answers of 7659 teachers to a survey. The findings showed that creativity was a recurring element of curricula but its incidence varied widely. It was also found that creativity was represented in arts subjects more than other subjects and that it was relatively neglected in reading and writing as part of the language group of subjects. The countries of theUKin general had maintained their historic attention to creativity but there was evidence of a shift from emphasis in primary settings to secondary settings. It is concluded that there is a need for much greater coherence between general aims for education and the representation of creativity in curriculum texts.
Human epithelial hair follicle stem cells and their progeny: Current state of knowledge, the widening gap in translational research and future challenges
Authors: Purba Talveen S. , Haslam Iain S. , Poblet Enrique , Jiménez Francisco , Gandarillas Alberto , Izeta Ander , Paus Ralf
Published: March 2014

Epithelial hair follicle stem cells (eHFSCs) are required to generate, maintain and renew the continuously cycling hair follicle (HF), supply cells that produce the keratinized hair shaft and aid in the reepithelialization of injured skin. Therefore, their study is biologically and clinically important, from alopecia to carcinogenesis and regenerative medicine. However, human eHFSCs remain ill defined compared to their murine counterparts, and it is unclear which murine eHFSC markers really apply to the human HF. We address this by reviewing current concepts on human eHFSC biology, their immediate progeny and their molecular markers, focusing on Keratin 15 and 19, CD200, CD34, PHLDA1, and EpCAM/Ber‐EP4. After delineating how human eHFSCs may be selectively targeted experimentally, we close by defining as yet unmet key challenges in human eHFSC research. The ultimate goal is to transfer emerging concepts from murine epithelial stem cell biology to human HF physiology and pathology.