bluuebunny/crossref_metadata_2025 huggingface dataset:
Deducing the spatial variability of exchange within a longitudinal channel water balance
Authors: Schmadel Noah M. , Neilson Bethany T. , Kasahara Tamao
Published: April 2013

Developing an appropriate data collection scheme to infer stream–subsurface interactions is not trivial due to the spatial and temporal variability of exchange flowpaths. Within the context of a case study, this paper presents the results from a number of common data collection techniques ranging from point to reach scales used in combination to better understand the spatial complexity of subsurface exchanges, infer the hydrologic conditions where individual influences of hyporheic and groundwater exchange components on stream water can be characterized, and determine where gaps in information arise. We start with a tracer‐based, longitudinal channel water balance to quantify hydrologic gains and losses at a sub‐reach scale nested within two consecutive reaches. Next, we look at groundwater and stream water surface levels, shallow streambed vertical head gradients, streambed and aquifer hydraulic conductivities, water chemistry, and vertical flux rates estimated from streambed temperatures to provide more spatially explicit information. As a result, a clearer spatial understanding of gains and losses was provided, but some limitations in interpreting results were identified even when combining information collected over various scales. Due to spatial variability of exchanges and areas of mixing, each technique frequently captured a combination of groundwater and hyporheic exchange components. Ultimately, this study provides information regarding technique selection, emphasizes that care must be taken when interpreting results, and identifies the need to apply or develop more advanced methods for understanding subsurface exchanges. Copyright © 2013 John Wiley & Sons, Ltd.
Quantification of doxorubicin in biofluids using white light excitation fluorescence
Authors: Prakash John , Mishra Ashok Kumar
Published: April 2013

A fiber optic spectrometer setup was designed for white light excitation fluorescence ‘WLEF’ based measurements. Using this setup, two different analytical methods, a self referencing ratio‐metric and a difference WLEF methods, were developed for the quantification of doxorubicin (DXR) in biofluids. It was seen that Acetonitrile (ACN) acts as an efficient and transparent extracting medium for DXR. The figures of merit and the percent recoveries of DXR in blood serum, even in presence of external fluorophores and in urine samples are comparable with existing analytical methods. The compact spectrometer is expected to be useful for easy quantification of fluorescent pharmaceuticals in biofluids. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Facile One‐pot Synthesis of Substituted Dihydropyrrol‐2‐ones via Four‐component Domino Reaction of Amines, Dialkyl Acetylenedicarboxylates and Formaldehyde
Authors: Sajadikhah Seyed Sajad , Hazeri Nourallah , Maghsoodlou Malek Taher , Habibi‐Khorassani Sayyed Mostafa
Published: April 2013

A mild and efficient method for the one‐pot synthesis of substituted dihydropyrrol‐2‐one derivatives is described via four‐component domino reaction of amines, dialkyl acetylenedicarboxyaltes and formaldehyde in the presence of 1‐methyl‐2‐oxopyrrolidinium hydrogen sulfate ([Hpyro][HSO4]) as ionic liquid catalyst. This facile approach proceeded smoothly in good to high yields and pure products are separated from the reaction mixture by simple filtration.
Targeting deregulated epigenetic control in cancer
Authors: Zaidi Sayyed K. , Van Wijnen Andre J. , Lian Jane B. , Stein Janet L. , Stein Gary S.
Published: April 2013

Cancer is a multifaceted disease that involves acquisition of genetic mutations, deletions, and amplifications as well as deregulation of epigenetic mechanisms that fine‐tune gene regulation. Key epigenetic mechanisms that include histone modifications, DNA methylation, and non‐coding RNA‐mediated gene silencing are often deregulated in a variety of cancers. Subnuclear localization of key proteins in the interphase nucleus and bookmarking of genes by lineage commitment factors in mitosis—a new dimension to epigenetic control of fundamental biological processes—is also modified in cancer. In this review, we discuss the various aspects of epigenetic control that are operative in a variety of cancers and their potential for risk assessment, early detection, targeted therapy, and personalized medicine. J. Cell. Physiol. 228: 2103–2108, 2013. © 2013 Wiley Periodicals, Inc.
Sediment disentrainment and the concept of local versus nonlocal transport on hillslopes
Authors: Furbish David Jon , Roering Joshua J.
Published: April 2013

A local formulation of the sediment flux on a hillslope describes the flux as a unique function of local hillslope conditions at any contour position x, whereas a nonlocal formulation must take into account nonlocal (upslope or downslope) conditions that influence the flux at x. Local formulations are reasonable when particle motions involve small length scales associated with localized bioturbation of the soil column or with proximal surface transport such as rain splash. Nonlocal formulations may be more appropriate in steeplands where patchy, intermittent motions involve large travel distances, mostly over the surface. Once sediment motions are initiated, the disentrainment process determines the distribution of particle travel distances, which, in turn, forms the basis of nonlocal formulations that involve a convolution of hillslope surface conditions, for example, the land‐surface slope. The kernel in the convolution integral, which weights the effect of land‐surface conditions (e.g., slope) at all positions upslope or downslope of x, derives from the formulation of the disentrainment rate and characterizes whether particle travel distances depend on conditions at the position where motions originate or vary as particles experience changing surface conditions during their downslope motions. If hillslope properties controlling transport (e.g., surface slope) are defined or measured at a specified resolution, then motions smaller than this resolution cannot be attributed to these properties resolved at a smaller scale. In essence, the relative importance of local and nonlocal transport depends on the scale of particle motions compared to the relevant scale of hillslope properties that drive transport.
Hyperpolarized 3He and 129Xe MRI: Differences in asthma before bronchodilation
Authors: Svenningsen Sarah , Kirby Miranda , Starr Danielle , Leary Del , Wheatley Andrew , Maksym Geoffrey N. , McCormack David G. , Parraga Grace
Published: April 2013

Purpose

To compare hyperpolarized helium‐3 (3He) and xenon‐129 (129Xe) MRI in asthmatics before and after salbutamol inhalation.

Materials and Methods

Seven asthmatics provided written informed consent and underwent spirometry, plethysmography, and MRI before and after salbutamol inhalation. 3He and 129Xe ventilation defect percent (VDP) and ventilation coefficient of variation (COV) were measured. To characterize the airways spatially related to ventilation defects, wall area percent (WA%) and lumen area (LA) were evaluated for two subjects who had thoracic x‐ray computed tomography (CT) acquired 1 year before MRI.

Results

Before salbutamol inhalation, 129Xe VDP (8 ± 5%) was significantly greater than 3He VDP (6 ± 5%, P = 0.003). Post‐salbutamol, there was a significant improvement in both 129Xe (5 ± 4%, P < 0.0001) and 3He (4 ± 3%, P = 0.001) VDP, and the improvement in 129Xe VDP was significantly greater (P = 0.008). 129Xe MRI COV (Pre: 0.309 ± 0.028, Post: 0.296 ± 0.036) was significantly greater than 3He MRI COV (Pre: 0.282 ± 0.018, Post: 0.269 ± 0.024), pre‐ (P < 0.0001) and post‐salbutamol (P < 0.0001) and the decrease in COV post‐salbutamol was significant (129Xe, P = 0.002; 3He, P < 0.0001). For a single asthmatic, a sub‐segmental 129Xe MRI ventilation defect that was visible only before salbutamol inhalation but not visible using 3He MRI was spatially related to a remodeled fourth generation sub‐segmental airway (WA% = 78%, LA = 2.9 mm2).

Conclusion

In asthma, hyperpolarized 129Xe MRI may help reveal ventilation abnormalities before bronchodilation that are not observed using hyperpolarized 3He MRI. J. Magn. Reson. Imaging 2013;38:1521–1530. © 2013 Wiley Periodicals, Inc.
Apparent diffusion coefficient value reflects invasive and proliferative potential of bladder cancer
Authors: Kobayashi Shuichiro , Koga Fumitaka , Kajino Kohei , Yoshita Soichiro , Ishii Chikako , Tanaka Hiroshi , Saito Kazutaka , Masuda Hitoshi , Fujii Yasuhisa , Yamada Tetsuo , Kihara Kazunori
Published: April 2013

Purpose

To elucidate a role of apparent diffusion coefficient (ADC) value as a biomarker of bladder cancer, we investigated its associations with Ki‐67 labeling index (LI) along with classical clinicopathological prognosticators.

Materials and Methods

Diffusion‐weighted MRI (DW‐MRI) at 1.5 Tesla using b‐values of 0, 500, 1000, and 2000 s/mm2 was prospectively taken before transurethral resection by 132 bladder cancer patients. ADC value of index tumors was measured and compared with clinicopathological prognosticators including Ki‐67 LI.

Results

ADC value was significantly lower in tumors with higher Ki‐67 LIs, sessile tumors (versus papillary), larger tumors, higher grade disease, and higher T stage disease. ADC value inversely correlated with Ki‐67 LI (ρ = −0.57; P < 0.0001). On multiple regression analysis, T stage and Ki‐67 LI significantly correlated with ADC value. The Akaike information criterion confirms these two parameters constitute the best model for determining ADC value. Similarly, T stage and ADC value significantly correlated with Ki‐67 LI and these two parameters composed the best model for predicting Ki‐67 LI.

Conclusion

ADC value would reflect T stage and Ki‐67 LI, representing invasive and proliferative potential, respectively. ADC value is likely to serve as a biomarker reflecting aggressiveness of bladder cancer. J. Magn. Reson. Imaging 2014;39:172–178. © 2013 Wiley Periodicals, Inc.
Methodological improvements in voxel‐based analysis of diffusion tensor images: Applications to study the impact of apolipoprotein E on white matter integrity
Authors: Newlander Shawn M. , Chu Alan , Sinha Usha S. , Lu Po H. , Bartzokis George
Published: April 2013

Purpose

To identify regional differences in apparent diffusion coefficient (ADC) and fractional anisotropy (FA) using customized preprocessing before voxel‐based analysis (VBA) in 14 normal subjects with the specific genes that decrease (apolipoprotein [APO] E ε2) and that increase (APOE ε4) the risk of Alzheimer's disease.

Materials and Methods

Diffusion tensor images (DTI) acquired at 1.5 Tesla were denoised with a total variation tensor regularization algorithm before affine and nonlinear registration to generate a common reference frame for the image volumes of all subjects. Anisotropic and isotropic smoothing with varying kernel sizes was applied to the aligned data before VBA to determine regional differences between cohorts segregated by allele status.

Results

VBA on the denoised tensor data identified regions of reduced FA in APOE ε4 compared with the APOE ε2 healthy older carriers. The most consistent results were obtained using the denoised tensor and anisotropic smoothing before statistical testing. In contrast, isotropic smoothing identified regional differences for small filter sizes alone, emphasizing that this method introduces bias in FA values for higher kernel sizes.

Conclusion

Voxel‐based DTI analysis can be performed on low signal to noise ratio images to detect subtle regional differences in cohorts using the proposed preprocessing techniques.J. Magn. Reson. Imaging 2014;39:387–397. ©2013 Wiley Periodicals, Inc.
Simultaneous determination of three alkaloids, four ginsenosides and limonin in the plasma of normal and headache rats after oral administration of Wu‐Zhu‐Yu decoction by a novel ultra fast liquid chromatography‐tandem mass spectrometry method: application to a comparative pharmacokinetics and ethological study
Authors: Xu Huarong , Li Qing , Yin Yidi , Lv Chunxiao , Sun Wanyang , He Bosai , Liu Ran , Chen Xiaohui , Bi Kaishun
Published: April 2013

A novel, sensitive and reliable ultra fast liquid chromatography‐tandem mass spectrometry (UFLC‐MS/MS) method has been developed and validated for simultaneous quantitation of eight main active ingredients (evodiamine, rutaecarpine, dehydroevodiamine, limonin, ginsenoside Rb1, Rd, Re and Rg1) in rat plasma after oral administration of Wu‐Zhu‐Yu (WZY) decoction, which is a celebrated and widely used Traditional Chinese Medicine formula for the treatment of headache. The analytes and internal standard (IS) were separated on a SHIM‐PACK XR‐ODS II column, and the detection was performed on a UFLC‐MS/MS system with turbo ion spray source. The lower limits of quantification were 1.5, 0.5, 1.0, 2.0, 2.0, 1.0, 0.5 and 0.2 ng ml−1 for evodiamine, rutaecarpine, dehydroevodiamine, limonin, gensenoside Rb1, Rd, Re and Rg1, respectively. Linearity, accuracy, precision and absolute recoveries of the eight analytes were all within satisfaction. The IS‐normalized matrix factor was adopted for assessing the matrix effect and accompanied with a satisfactory result. The validated method has been successfully applied to compare pharmacokinetic profiles of the eight active ingredients in rat plasma between normal and headache rats after administration. Exact pharmaceutical effect of WZY decoction on headache was demonstrated by the ethological response of headache rats induced by nitric oxide donor after administration. The results indicated that the absorption of evodiamine, rutaecarpine, gensenoside Rb1, Re and Rg1 in headache group were significantly higher than those in normal group with similar concentration–time curves while no significant differences existed in limonin and ginsenoside Rd between the two groups. Copyright © 2013 John Wiley & Sons, Ltd.
Universal proteolysis and MSn for N‐ and O‐ glycan branching analysis
Authors: Schiel John E. , Smith Nicholas J. , Phinney Karen W.
Published: April 2013

The continually growing list of critical glycosylation‐related processes has made analytical methodology for detailed glycan characterization an area of increasing interest. Glycosylation is a post translational modification of unsurpassed complexity due to the variety of compositions and linkages formed by these biopolymers. Structural characterization of glycan isomers has been achieved using ion trap mass spectrometry and MSn of released, permethylated glycans. However, N‐ and O‐glycans require different sample preparation strategies; and release of the glycans may be hindered, result in degradation of the glycan, and/or produce limited yields of permethylated product. In the current report, we demonstrate universal proteolysis of both N‐ and O‐linked glycoproteins to individual glycoamino acids. These samples were shown to be directly amenable to permethylation and MSn analysis for isomeric structural determination. Universal proteolysis and permethylation provides an identical sample preparation strategy for both classes of glycans that avoids potential pitfalls of commonly used release methods. This methodology should be applicable to all glycoproteins and serve as an alternative to glycan release for MSn branching analysis. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.
Human papillomavirus was not detected by PCR using multiple consensus primer sets in esophageal adenocarcinomas in Chinese patients
Authors: Feng Songtao , Zheng Jianming , Du Xiang , Tan Yunshan , Yang Haijun , Zhang Hongxia , Zhang Zhigang
Published: April 2013

The role of human papillomavirus (HPV) infection in the development of esophageal squamous cell carcinoma is well established; however, there are few reports on the role of HPV in esophageal adenocarcinoma. To evaluate the putative role of HPV infection in esophageal adenocarcinoma, 57 formalin‐fixed, paraffin‐embedded esophageal adenocarcinoma specimens were collected from four hospitals in Shanghai and Anyang, China, between 1999 and 2008. HPV DNA was analyzed using PCR with multiple sets of consensus primers for HPV, GP5+/6+, CPI/CPIIG, SPF10, pU‐1M/pU2R, and pU31B/pU2R. Glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH), the internal control, was amplified successfully in all 57 specimens. However, HPV amplification was not detected in any specimens with any of the consensus primer sets used. The present study indicates that HPV infection is not likely to be a major factor in the etiology of esophageal adenocarcinoma in the Chinese population. J. Med. Virol. 85: 1053–1057, 2013. © 2013 Wiley Periodicals, Inc.
CCR5 Δ 32 mutation is not prevalent in Iranians with chronic HBV infection
Authors: Khorramdelazad Hossein , Hakimizadeh Elham , Hassanshahi Gholamhossein , Rezayati Mohammadtaghi , Sendi Hossein , Arababadi Mohammad Kazemi
Published: April 2013

CCR5 is an important chemokine receptor involved in the recruitment of specific anti‐viral immune cells (e.g., NK cells and T cytotoxic cells) to the liver. Previous studies indicated that the Δ 32 mutation in CCR5 gene led to inactivation of CCR5. Several conflicting studies have suggested that this mutation may be associated with either recovery or persistence of HBV infection. The main purpose of this study was to compare the frequency of the Δ 32 mutation within the CCR5 gene in a group of patients infected chronically with HBV with healthy individuals from South‐East of Iran. Sixty patients with chronic HBV infection as well as 300 age‐, and sex‐match healthy individuals were enrolled in this study. Gap‐PCR was applied to determine the frequency of CCR5 Δ 32 mutation in both groups. The results demonstrated that none of the patients infected with HBV carried the CCR5 Δ 32 mutation while, 3 (1%) of the healthy individuals were found to be heterozygotic for this mutation. The CCR5 Δ 32 mutation is not a prevalent mutation in either the patients infected chronically with HBV or their health counterparts in the South‐East region of Iran. This may be attributed to either different genetic settings of the investigated population or lack of any significant correlation between this mutation and HBV pathogenicity. J. Med. Virol. 85: 964–968, 2013. © 2013 Wiley Periodicals, Inc.
Molecular analysis of the hepatitis B virus presurface and surface gene in patients from eastern China with occult hepatitis B
Authors: Huang Xiangyan , Qin Yanghua , Li Wei , Shi Qingfen , Xue Yan , Li Jie , Liu Chao , Hollinger F. Blaine , Shen Qian
Published: April 2013

This study was designed to detect and analyze mutations that occur within the presurface and surface (pre‐S/S) gene of HBV in patients with occult hepatitis B, and determine their relationship to that disorder. Among 254 HBsAg negative samples of blood collected in eastern China, 183 were positive for anti‐HBc alone, 61 were positive for anti‐HBe alone, and 10 samples were positive for HBeAg. Within this group, 15 samples were found to be HBV DNA positive by real‐time PCR and were designated Group I. A control group of 28 HBsAg positive samples were chosen at random from patients with chronic hepatitis B and designated Group II. The HBV pre‐S/S gene was amplified by PCR and subjected to sequencing analysis. Occult hepatitis B was found in 1.6% of the patients with anti‐HBc alone and in 3.3% of those with anti‐HBe alone. Occult hepatitis B also was found in all HBsAg negative but HBeAg positive samples. Sequencing analysis showed a significant correlation between point mutations within the “a” determinant and occult hepatitis B (P < 0.0001), and a close relationship between pre‐S deletion mutations and occult hepatitis B (P = 0.06). There were unique amino acid mutations at the G145 position other than G145R. The HBV DNA levels in patients with occult hepatitis B were significantly lower than those found in the control group. The “a” determinant mutations and pre‐S deletions may play important roles in occult hepatitis B by affecting the expression, synthesis and secretion of the S protein and by impeding viral release and replication. J. Med. Virol. 85: 979–986, 2013. © 2013 Wiley Periodicals, Inc.
Case report: Oseltamivir‐induced resistant pandemic influenza A (H1N1) Virus infection in a patient with AIDS and Pneumocystis jirovecii pneumonia
Authors: van Kampen Jeroen J.A. , Bielefeld‐Buss Astrid J. , Ott Alewijn , Maaskant Jolanda , Faber Harald J. , Lutisan Johan G. , Boucher Charles A.B.
Published: April 2013

Pneumocystis jirovecii pneumonia is the main cause of severe respiratory failure in patients with advanced HIV disease who do not receive P. jirovecii prophylaxis. Other aetiological agents may contribute to the respiratory failure in these patients, which is highlighted by the case described below: A patient with advanced HIV disease was treated for a dual‐infection with pandemic influenza A (H1N1) and P. jirovecii. Initially, his condition improved, but deteriorated after the emergence of oseltamivir‐resistant influenza virus. This is the first documented case of emergence of drug‐resistant influenza virus in a patient infected with HIV with a pandemic influenza A (H1N1) and P. jirovecii double infection. J. Med. Virol. 85: 941–943, 2013. © 2013 Wiley Periodicals, Inc.
Impact of peginterferon alpha‐2b and entecavir hydrate combination therapy on persistent viral suppression in patients with chronic hepatitis B
Authors: Hagiwara Satoru , Kudo Masatoshi , Osaki Yukio , Matsuo Hiroo , Inuzuka Tadashi , Matsumoto Akihiro , Tanaka Eiji , Sakurai Toshiharu , Ueshima Kazuomi , Inoue Tatsuo , Yada Norihisa , Nishida Naoshi
Published: April 2013

The ideal approach to treat chronic hepatitis B remains controversial. This pilot study aimed to evaluate the effectiveness of peginterferon (PEG‐IFN) α‐2b and entecavir hydrate (ETV) as a combination therapy for patients with chronic hepatitis B, particularly in the context of virological response and the reduction of intrahepatic covalently closed circular DNA (cccDNA). A total of 17 patients with hepatitis B virus (HBV) genotype C were enrolled in this study. All subjects were treated with this combination therapy for 48 weeks and observed for an additional 24 weeks. All patients underwent liver biopsy before and after the therapy period. Changes in cccDNA levels and liver histology were monitored between biopsies. Among the 11 patients who exhibited pre‐therapy hepatitis B e antigen (HBeAg), 8 (73%) showed evidence of HBeAg seroconversion by the end of the follow‐up period. Serum HBV DNA levels decreased by 5.2 and 3.3 log copies/ml (mean) by the end of the therapy and follow‐up periods, respectively. In addition, intrahepatic cccDNA decreased significantly to 1.4 log copies/µg (mean) by the end of the therapy period. Among the 11 patients who did not experience viral relapse, only 2 (18%) exhibited high levels of cccDNA (>4.5 log copies/µg) by the end of the treatment period. In contrast, all relapsed subjects exhibited significantly higher levels of cccDNA than subjects who did not relapse (P = 0.027). The combination regimen is a promising approach to treat chronic hepatitis B and may achieve significant reduction in serum HBV DNA and intrahepatic cccDNA. J. Med. Virol. 85: 987–995, 2013. © 2013 Wiley Periodicals, Inc.
Emergence of telaprevir‐resistant variants detected by ultra‐deep sequencing after triple therapy in patients infected with HCV genotype 1
Authors: Akuta Norio , Suzuki Fumitaka , Seko Yuya , Kawamura Yusuke , Sezaki Hitomi , Suzuki Yoshiyuki , Hosaka Tetsuya , Kobayashi Masahiro , Hara Tasuku , Kobayashi Mariko , Saitoh Satoshi , Arase Yasuji , Ikeda Kenji , Kumada Hiromitsu
Published: April 2013

Using ultra‐deep sequencing technology, the present was designed to investigate whether the emergence of telaprevir‐resistant variants (amino acid substitutions of aa36, aa54, aa155, aa156, and aa170 positions in HCV NS3 region) after commencement of triple therapy of telaprevir/peginterferon (PEG‐IFN)/ribavirin could be predicted at baseline in previous non‐responders to dual therapy. Fourteen patients infected with HCV genotype 1 who did not respond to previous PEG‐IFN/ribavirin, received a 24‐week regimen of triple therapy, and were evaluated for appearance of telaprevir‐resistant variants (amino acid substitutions of more than 0.2% among the total coverage) by ultra‐deep sequencing. The sustained virological response rate was 28.6% (4 of 14 patients), which was significantly higher in patients with Arg70 (substitution at core aa70) and partial response (type of previous response to PEG‐IFN/ribavirin) than in other patients. Telaprevir‐resistant variants at baseline were detected in 7.1% (1 of 14 patients) by direct sequencing and in 21.4% (3 of 14 patients) by ultra‐deep sequencing. The appearance of telaprevir‐resistant variants was examined by ultra‐deep sequencing in 10 who did not show sustained virological responders. De novo variants emerged at re‐elevation of viral load, regardless of variant frequencies at baseline (one patient with very high frequency variants [T54S: 99.9%], two patients with very low frequency variants [V36A: 0.2%; and V170A: 0.4%], and seven patients of undetectable variants). It is concluded that it is difficult to predict at baseline the emergence of telaprevir‐resistant variants after commencement of triple therapy in prior non‐responders of HCV genotype 1, even with the use of ultra‐deep sequencing. J. Med. Virol. 85: 1028–1036, 2013. © 2013 Wiley Periodicals, Inc.
Results on value distribution of L‐functions
Authors: Li Xiao‐Min , Yi Hong‐Xun
Published: April 2013

We will establish a theorem concerning value distribution of L‐functions in the Selberg class, which shows how an L‐function and a meromorphic function are uniquely determined by their c‐values and which, as a consequence, proves a result on the uniqueness of the Riemann zeta function. The results in this paper also extend the corresponding ones in Li 6.
Effect of Zinc Oxide Nanoparticles Concentration on the Mechanical Properties and UV Protection of In Situ Synthesized ABS Based Nanocomposites
Authors: Rodríguez‐Tobías Heriberto , Morales Graciela , Rodríguez‐Fernández Oliverio , Acuña Pablo
Published: April 2013

A series of ABS/ZnO nanocomposites with different nanoparticles content were synthesized by mass‐mass and mass‐suspension processes. Because nanocomposites obtained through mass‐suspension process had a greater impact resistance than those derived from mass‐mass process, they were subjected to twin‐screw extrusion. The extrusion led to a dramatic morphological change and increase in impact resistance, higher than 100% in most of the cases. On the other hand, the higher the ZnO content, the higher the UV blocking (>95% for 1 and 3% of ZnO) for both materials, before and after extrusion.
Solvent Effects in Semibatch Free Radical Copolymerization of 2‐Hydroxyethyl methacrylate and Styrene at High Temperatures
Authors: Liang Kun , Hutchinson Robin A.
Published: April 2013

High temperature semibatch free radical copolymerizations of 2‐hydroxyethyl methacrylate (HEMA) and styrene (ST) were carried out in xylene and DMF solution. Experimental free monomer and polymer molecular weight (MW) profiles at different temperatures and solvent concentrations are compared to those for ST polymerized with butyl methacrylate (BMA). Solvent choice, through its influence on hydrogen bonding of HEMA monomer, has a significant impact on the polymerization that is not seen for the corresponding ST/BMA reactions. The weight‐average polymer MWs of ST/HEMA are unusually high (>40 kg/mol), a result of branching reactions involving dimethacrylate impurity contained in HEMA monomer. The importance of these branching reactions is also influenced by solvent choice.
A Note on the Elasticity of Polymer Melts Described by Primary Normal Stress Difference (N1)
Authors: García‐Franco César A.
Published: April 2013

A method is proposed to characterize the elastic behavior of polyolefin melts, by calculating the first normal stress difference, N1 as a function of shear rate. The method is predicated on Cogswell's abrupt contraction flow analysis.1 These results are compared with experimental measurements and calculated values with a variety of methods, such as: i) Laun's rule2 for obtaining viscometric functions from linear viscoelastic data, ii) methods proposed by A. Khalik, et. al.3,4 and Wagner,5 for calculating N1 from viscosity data, and iii) N1 values calculated with the Johnson & Segalman constitutive equation.6 These comparisons yield acceptable agreement.
Synthesis of Amphiphilic Symmetrical ABA Triblock Copolymers PS‐b‐PEG‐b‐PS Using a Bifunctional Macro RAFT Agent
Authors: Cortez‐Lemus Norma A. , Baldenebro Víctor , Zizumbo‐Lopez Arturo , Licea‐Claverie Angel
Published: April 2013

This study involves the synthesis, characterization and study of self‐aggregation of PEG‐based amphiphilic triblock copolymers. PEG based difunctional macro RAFT agents were synthesized and characterized. PS‐b‐PEG‐b‐PS block copolymers were synthesized via the RAFT controlled free radical polymerization using the synthesized PEG dual macro RAFT agents. The content of polystyrene blocks on the triblocks was varied from 12% to 36% (based on molecular weight increase), adjusting the synthetic conditions. The triblocks self‐aggregate in Dioxane‐Water mixtures in sizes depending on the water content.
Maximum principle for the finite element solution of time‐dependent anisotropic diffusion problems
Authors: Li Xianping , Huang Weizhang
Published: April 2013

Preservation of the maximum principle is studied for the combination of the linear finite element method in space and the θ ‐method in time for solving time‐dependent anisotropic diffusion problems. It is shown that the numerical solution satisfies a discrete maximum principle when all element angles of the mesh measured in the metric specified by the inverse of the diffusion matrix are nonobtuse, and the time step size is bounded below and above by bounds proportional essentially to the square of the maximal element diameter. The lower bound requirement can be removed when a lumped mass matrix is used. In two dimensions, the mesh and time step conditions can be replaced by weaker Delaunay‐type conditions. Numerical results are presented to verify the theoretical findings. © 2013 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2013
Crossing the Limit Towards Deep UV
Authors: Orthaus Sandra , König Marcelle , Schönau Thomas , Buschmann Volker , Tannert Sebastian , Lauritsen Christian , Koberling Felix , Ortmann Uwe , Erdmann Rainer
Published: April 2013

Confocal microscopy allows for various fluorescence applications that have found their way into modern biology and medicine leading to new insights into morphology, physiology as well as pathological alterations. Common microscopical analyses include labeling of the sample with extrinsic fluorophores because DNA, saccharides, lipids, membranes, and most cellular structures are non‐fluorescent.
One Frame, Endless Possibilities
Authors: Hempell Wolfgang , Reiss Simon
Published: April 2013

To change the constraints of the traditional microscope system, Olympus has developed an new open source microscopy concept, based on the inverted IX3 microscope frame series. Designed around an accessible infinite light path concept, optical modules can be easily exchanged, moulding the microscope to the diverse requirements of the user. The series suits anything from routine observation to advanced imaging techniques in all live cell applications. Figure 1 shows an image taken using a semi‐confocal observation method with a disc‐scanning unit. The frames can be easily adapted to apply such observation methods.
Screening for dementia: diagnosis… and then what?
Authors: Hill Lisa , Walton Ian
Published: April 2013

Rather than promoting more screening to increase early diagnosis of dementia in primary care, the initial focus should be on providing adequate resources to support patients and carers in the community once a diagnosis has been made, argue Lisa Hill and Ian Walton.
Improved Approach to Predict the Power of Energetic Materials
Authors: Keshavarz Mohammad Hossein , Seif Farhad
Published: April 2013

Nowadays, the ballistic mortar is the preferred test for the explosive power measurements but there is no reliable method for its prediction. For an energetic compound, the formation of low molecular mass gaseous products and a high positive heat of formation per unit weight of the energetic compound are important parameters to have a high value of power. A novel method was developed to predict the power by the ballistic mortar test for pure and mixture of energetic materials. It can be used for some important classes of energetic compounds including nitroaromatics, acyclic and cyclic nitramines, nitrate esters, and nitroaliphatics. The presented method is based on the molecular structure of the desired compound and there is no need to use experimental data such as the condensed phase heat of formation. For 84 pure and 24 mixtures of energetic compounds, the calculated power relative to 2,4,6‐trinitrotoluene (= 100) show good agreement with respect to the measured values.
Antistatic Modification of Lead Styphnate and Lead Azide for Surfactant Applications
Authors: Zhou Mingrui , Li Zhimin , Zhou Zunning , Zhang Tonglai , Wu Bidong , Yang Li , Zhang Jianguo
Published: April 2013

Lead styphnate (LS) and lead azide (LA) must be considered vulnerable to accumulation and discharge of static charge under all conditions. To reduce the risk aroused by static initination hazard in the processing and handling of LS and LA, antistatic modifations of LS and LA are necessary. In this paper, four surfactants were applied to improve the antistatic abilities of lead styphnate and lead azide. The results showed that lauryl dimethylamine betaine (BS‐12) is significantly able to reduce the electrostatic accumulation of LS and LA. In addition, possible correlations of electrostatic accumulation with assumption and approximation could be drawn from the surfactant surface concentration. The electrostatic sensitivities, the 5 s delay explosion temperatures, and the thermal decomposition profiles of the compounds were measured. Selected products were additionally investigated by scanning electron microscopy (SEM). For LS the performance of the products with additives was less affected, whereas for LA the sensitivity of the products in the presence of surfactants was distinctly reduced. The surfactants which are preferably compatible with LS and LA do not affect their thermal stability.
Right‐ and left‐handed three‐helix proteins. I. Experimental and simulation analysis of differences in folding and structure
Authors: Glyakina Anna V. , Pereyaslavets Leonid B. , Galzitskaya Oxana V.
Published: April 2013

Despite the large number of publications on three‐helix protein folding, there is no study devoted to the influence of handedness on the rate of three‐helix protein folding. From the experimental studies, we make a conclusion that the left‐handed three‐helix proteins fold faster than the right‐handed ones. What may explain this difference? An important question arising in this paper is whether the modeling of protein folding can catch the difference between the protein folding rates of proteins with similar structures but with different folding mechanisms. To answer this question, the folding of eight three‐helix proteins (four right‐handed and four left‐handed), which are similar in size, was modeled using the Monte Carlo and dynamic programming methods. The studies allowed us to determine the orders of folding of the secondary‐structure elements in these domains and amino acid residues which are important for the folding. The obtained data are in good correlation with each other and with the experimental data. Structural analysis of these proteins demonstrated that the left‐handed domains have a lesser number of contacts per residue and a smaller radius of cross section than the right‐handed domains. This may be one of the explanations of the observed fact. The same tendency is observed for the large dataset consisting of 332 three‐helix proteins (238 right‐ and 94 left‐handed). From our analysis, we found that the left‐handed three‐helix proteins have some less‐dense packing that should result in faster folding for some proteins as compared to the case of right‐handed proteins.Proteins 2013; © 2013 Wiley Periodicals, Inc.
Quinolone Alkaloids from Fructus Euodiae Show Activity Against Methicillin‐Resistant Staphylococcus aureus
Authors: Pan Xiaobei , Bligh S. W. Annie , Smith Eileen
Published: April 2013

Fructus Euodiae is used in Traditional Chinese Medicine to treat infection. In this study, four of the quinolone alkaloids isolated from Fructus Euodiae showed activity against methicillin‐resistant Staphylococcus aureus (MRSA). The minimum inhibitory concentrations (MIC) were 8–128 µg/mL, which were equivalent to or lower than the control antibiotics, oxacillin, erythromycin and tetracycline (MIC ≥128 µg/mL). Among these isolated quinolone alkaloids, evocarpine with a 13 carbon alkenyl chain substituent at position‐2 showed the best activity against MRSA. This study has demonstrated the potential of quinolone alkaloids from Fructus Euodiae as anti‐MRSA compounds and supports the traditional use of the fruit as a treatment for bacterial infections. Copyright © 2013 John Wiley & Sons, Ltd.
Coenzyme Q10 quantification in muscle, fibroblasts and cerebrospinal fluid by liquid chromatography/tandem mass spectrometry using a novel deuterated internal standard
Authors: Duberley Kate E. C. , Hargreaves Iain P. , Chaiwatanasirikul Korn‐Anong , Heales Simon J. R. , Land John M. , Rahman Shamima , Mills Kevin , Eaton Simon
Published: April 2013

RATIONALE

Neurological dysfunction is common in primary coenzyme Q10 (2,3‐dimethoxy, 5‐methyl, 6‐polyisoprene parabenzoquinone; CoQ10; ubiquinone) deficiencies, the most readily treatable subgroup of mitochondrial disorders. Therapeutic benefit from CoQ10 supplementation has also been noted in other neurodegenerative diseases. CoQ10 can be measured by high‐performance liquid chromatography (HPLC) in plasma, muscle or leucocytes; however, there is no reliable method to quantify CoQ10 in cerebrospinal fluid (CSF). Additionally, many methods use CoQ9, an endogenous ubiquinone in humans, as an internal standard.

METHODS

Deuterated CoQ10 (d6‐CoQ10) was synthesised by a novel, simple, method. Total CoQ10 was measured by liquid chromatography/tandem mass spectrometry (LC/MS/MS) using d6‐CoQ10 as internal standard and 5 mM methylamine as an ion‐pairing reagent. Chromatography was performed using a Hypsersil GOLD C4 column (150 × 3 mm, 3 µm).

RESULTS

CoQ10 levels were linear over a concentration range of 0–200 nM (R2 = 0.9995). The lower limit of detection was 2 nM. The inter‐assay coefficient of variation (CV) was 3.6% (10 nM) and 4.3% (20 nM), and intra‐assay CV 3.4% (10 nM) and 3.6% (20 nM). Reference ranges were established for CoQ10 in CSF (5.7–8.7 nM; n = 17), fibroblasts (57.0–121.6 pmol/mg; n = 50) and muscle (187.3–430.1 pmol/mg; n = 15).

CONCLUSIONS

Use of d6‐CoQ10 internal standard has enabled the development of a sensitive LC/MS/MS method to accurately determine total CoQ10 levels. Clinical applications of CSF CoQ10 determination include identification of patients with cerebral CoQ10 deficiency, and monitoring CSF CoQ10 levels following supplementation. Copyright © 2013 John Wiley & Sons, Ltd.
Speciation of platinum‐benzoylthiourea in the gas phase using electrospray ionization mass spectrometry and density functional theory
Authors: Kumar Pranaw , Jaison P. G. , Sundararajan Mahesh , Telmore Vijay M. , Ghosh Swapan K. , Aggarwal Suresh K.
Published: April 2013

RATIONALE

Determining the speciation of platinum‐benzoylthiourea (Pt‐BTU) in the gas phase is a challenging task due to various reaction pathways and the conformational flexibility of the BTU ligand.

METHODS

Electrospray ionization mass spectrometry (ESI‐MS) experiments and density functional theory (DFT) based calculations were carried out to shed light on this complex reaction in the gas phase using K2PtCl4salt and BTU. Various Pt complexes were studied in both positive and negative ion modes of ESI‐MS using a quadrupole‐time‐of‐flight mass spectrometer. The effects of the ESI‐MS experimental parameters such as capillary voltage, pH and electrolyte on the peak intensity of the Pt‐BTU complex were investigated. DFT calculations employing B3LYP functional with the 6‐311++G** basis set were used to characterize the geometric parameters and fragmentation patterns of various Pt complexes in the gas phase.

RESULTS

In the positive ion mode, complexes with differing numbers of BTU ligands coordinated to the metal ion were observed, whereas, in the negative ion mode, no species associated with BTU or with the solvent (acetonitrile) molecules were found. It was also found that Pt forms complexes with the BTU ligand in different stoichiometric ratios. For both Pt(BTU)2and Pt(BTU)3complexes, the BTU ligand undergoes deprotonation followed by bi‐dentate coordination. DFT calculations suggest that BTU can coordinate to Pt in bothcisandtransisomeric forms, which are nearly iso‐energetic with a slight preference towards thetrans‐isomer. The preference oftrans‐BTU binding is attributed to the exclusive retention of intra‐molecular hydrogen bonding which is absent in thecis‐form.

CONCLUSIONS

Experimental and theoretical calculations have shown that the gas‐phase interaction of BTU to Pt is very complex. The BTU ligand can coordinate to Pt in both mono‐dentate and bi‐dentate modes, the latter mode being favorable upon deprotonation of the BTU ligand. Furthermore, many close lying species with different geometric isomeric forms are found to be possible due to the presence of intra‐ and inter‐molecular hydrogen bonding. Copyright © 2013 John Wiley & Sons, Ltd.
The Association of Family Influence and Initial Interest in Science
Authors: DABNEY KATHERINE P. , CHAKRAVERTY DEVASMITA , TAI ROBERT H.
Published: April 2013

With recent attention to improving scientific workforce development and student achievement, there has been a rise in effort to understand and encourage student engagement in physical science. This study examines the association of family influence and initial interest in science through multiple and logistic regression models. Research questions addressed include Controlling for demographic variables, are physical science doctoral students or scientists who report family as a primary source of interest in science, as opposed to those that do not, more likely to develop an early interest in science? And what specific forms of family support are associated with doctoral students or scientists who report family as a primary source of initial interest in science? The study uses survey data from Project Crossover (n= 4,285), a sequential mixed methods study that examines factors influencing entrance into physical science doctoral programs as well as the transition from graduate students to independent researcher. Results suggest that family interest in science facilitates earlier initial interest in science. Further analyses show that family influence shifts from parental occupation as the primary source of interest for the older generation of scientists to one of three influences (occupation, diversion or hobby, and encouragement) among doctoral students. © 2013Wiley Periodicals, Inc. Sci Ed 97:395–409, 2013
Synergetic Material and Structure Optimization Yields Robust Spider Web Anchorages
Authors: Pugno Nicola M. , Cranford Steven W. , Buehler Markus J.
Published: April 2013

Millions of years of evolution have adapted spider webs to achieve a range of properties, including the well‐known capture of prey, with efficient use of materials. One feature that remains poorly understood is the attachment disc, a network of silk fibers that mechanically anchors a web to its environment. Experimental observations suggest that one possible attachment disc adheres to a substrate through multiple symmetrically branched structures composed of sub‐micrometer scale silk fibers. Here, a theoretical model is used to explore the adaptation of the strength of attachment of such an anchorage, and complementary mesoscale simulations are applied to demonstrate a novel mechanism of synergetic material and structural optimization, such that the maximum anchorage strength can be achieved regardless of the initial anchor placement or material type. The optimal delamination (peeling) angle is facilitated by the inherent extensibility of silk, and is attained automatically during the process of delamination. This concept of self‐optimizing peeling angle suggests that attachment discs do not require precise placement by the spider, irrespective of adhesion strength. Additional hierarchical branching of the anchorage increases efficiency, where both the delamination force and toughness modulus increase with a splitting of the cross‐sectional area.
Single Layer of Polymeric Cobalt Phthalocyanine: Promising Low‐Cost and High‐Activity Nanocatalysts for CO Oxidation
Authors: Deng Qingming , Zhao Lina , Gao Xingfa , Zhang Meng , Luo Youhua , Zhao Yuliang
Published: April 2013

The catalytic behavior of transition metals (Sc to Zn) combined in polymeric phthalocyanine (Pc) is investigated systematically by using first‐principles calculations. The results indicate that CoPc exhibits the highest catalytic activity for CO oxidation at room temperature with low energy barriers. By exploring the two well‐established mechanisms for CO oxidation with O2, namely, the Langmuir–Hinshelwood (LH) and the Eley–Rideal (ER) mechanisms, it is found that the first step of CO oxidation catalyzed by CoPc is the LH mechanism (CO + O2 → CO2 + O) with energy barrier as low as 0.65 eV. The second step proceeds via both ER and LH mechanisms (CO + O → CO2) with small energy barriers of 0.10 and 0.12 eV, respectively. The electronic resonance among Co‐3d, CO‐2π*, and O2‐2π* orbitals is responsible for the high activity of CoPc. These results have significant implications for a novel avenue to fabricate organometallic sheet nanocatalysts for CO oxidation with low cost and high activity.
The I Don't Know Option in the Vocabulary Size Test
Authors: Zhang Xian
Published: April 2013

The current study evaluates guessing behaviors in a vocabulary size test (VST) and examines whether including an I don't know in a VST may have an impact on the results of the test. One‐hundred‐fifty first‐year students at a university in China took part in the study. They were randomly assigned to three groups. Each group took a different version of the VST: the original VST, the VST with an I don't know option, and the VST with an I don't know option and a penalty instruction. After the VST, a reading comprehension test (used as a distraction) and a meaning recall task were administered to all participants. Comparing the results of the VST and the recall task, it was found that guessing behaviors can be influenced by factors such as vocabulary frequency level, partial knowledge, and the multiple‐choice options. Results also indicate that the I don't know option not only reduced the number of guesses but also discouraged partial knowledge. Whether to include the I don't know option and the penalty instruction depends on how the test is to be used.
Anthropological contributions to the study of climate: past, present, future
Authors: Hastrup Kirsten
Published: April 2013

In the world of climate science there is an increasing demand for contributions from the social sciences, given that the current processes of climate change deeply affect societies. This article is a response to this call, with specific focus on past and potential contributions from anthropology, as we have known it from the 19th century onwards. It is shown how through the ages, different anthropological interests have shaped distinct perspectives on the entanglement of society and nature. It is argued that the present global concerns about climate change necessitate a refashioning of anthropology, and make it expedient to pay attention to the emergent global imaginaries.WIREs Clim Change2013, 4:269–281. doi: 10.1002/wcc.219

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Climate, History, Society, Culture > Disciplinary Perspectives