bluuebunny/crossref_metadata_2025 huggingface dataset:
Accurate timekeeping is controlled by a cycling activator in Arabidopsis
Authors: Hsu Polly Yingshan , Devisetty Upendra K , Harmer Stacey L
Published: April 2013

Transcriptional feedback loops are key to circadian clock function in many organisms. Current models of the Arabidopsis circadian network consist of several coupled feedback loops composed almost exclusively of transcriptional repressors. Indeed, a central regulatory mechanism is the repression of evening-phased clock genes via the binding of morning-phased Myb-like repressors to evening element (EE) promoter motifs. We now demonstrate that a related Myb-like protein, REVEILLE8 (RVE8), is a direct transcriptional activator of EE-containing clock and output genes. Loss of RVE8 and its close homologs causes a delay and reduction in levels of evening-phased clock gene transcripts and significant lengthening of clock pace. Our data suggest a substantially revised model of the circadian oscillator, with a clock-regulated activator essential both for clock progression and control of clock outputs. Further, our work suggests that the plant clock consists of a highly interconnected, complex regulatory network rather than of coupled morning and evening feedback loops.
Native α-synuclein induces clustering of synaptic-vesicle mimics via binding to phospholipids and synaptobrevin-2/VAMP2
Authors: Diao Jiajie , Burré Jacqueline , Vivona Sandro , Cipriano Daniel J , Sharma Manu , Kyoung Minjoung , Südhof Thomas C , Brunger Axel T
Published: April 2013

α-Synuclein is a presynaptic protein that is implicated in Parkinson's and other neurodegenerative diseases. Physiologically, native α-synuclein promotes presynaptic SNARE-complex assembly, but its molecular mechanism of action remains unknown. Here, we found that native α-synuclein promotes clustering of synaptic-vesicle mimics, using a single-vesicle optical microscopy system. This vesicle-clustering activity was observed for both recombinant and native α-synuclein purified from mouse brain. Clustering was dependent on specific interactions of native α-synuclein with both synaptobrevin-2/VAMP2 and anionic lipids. Out of the three familial Parkinson's disease-related point mutants of α-synuclein, only the lipid-binding deficient mutation A30P disrupted clustering, hinting at a possible loss of function phenotype for this mutant. α-Synuclein had little effect on Ca2+-triggered fusion in our reconstituted single-vesicle system, consistent with in vivo data. α-Synuclein may therefore lead to accumulation of synaptic vesicles at the active zone, providing a ‘buffer’ of synaptic vesicles, without affecting neurotransmitter release itself.
The eLife approach to peer review
Authors: Schekman Randy , Watt Fiona , Weigel Detlef
Published: April 2013

All editorial decisions at eLife are taken by working scientists in a process that emphasizes fairness, speed and transparency.
Discretion in the “Backyard of Law”: Case Handling of Debt Relief in Sweden
Authors: Larsson Bengt , Jacobsson Bengt
Published: April 2013

This article explores discretion in welfare professional work. The aim is to analyse what room for discretionary decision-making that exist in case handling of debt relief at the Swedish Enforcement Authority (SEA). The analysis is guided by a conceptual distinction between structural and epistemic aspects of discretion, as well as between substantive and procedural aspects. The data comprises official and internal SEA documents, interviews with management and staff and field notes from observations. The analysis points to a change in the balance between standards and discretion in relation to the on-going formalization of case handling at the SEA, though not in the simplistic sense that discretion is diminished through formalization. When taking into account the different analytical aspects of discretion, it is concluded that discretion is narrowed only in some respects. There is still space for case officers in selecting and interpreting information and assess-ing the conditions regarding subject matter.
Risky Professions? Risk of Disability in Professions in Norway
Authors: Tufte Per Arne
Published: April 2013

Modern professions provide important and essential services like engineering, financial services, and welfare state services. Sustaining a sufficient supply of these services requires professionals to remain in the workforce as long as possible. This article examines variation in the risk of disability pension among individuals with different professional education backgrounds according to the status of the profession and its primary task (i.e., caring for others, “life” professions; or providing other kinds of services, “thing” professions). Event history analy-sis was employed to examine register data for the Norwegian population from 1992 through 2008, with gender, age at completed education, birth year, and social status as control variables. The results indicate that individuals in low-status life professions were exposed to a greater risk of disability pension than individuals with other professional education backgrounds. Possible explanations are mechanisms related to selection effects, physical and mental job strain, and professional ethics.
Controlled Growth of Porous α‐Fe2O3 Branches on β‐MnO2 Nanorods for Excellent Performance in Lithium‐Ion Batteries
Authors: Gu Xin , Chen Liang , Ju Zhicheng , Xu Huayun , Yang Jian , Qian Yitai
Published: April 2013

Hierarchical nanocomposites rationally designed in component and structure, are highly desirable for the development of lithium‐ion batteries, because they can take full advantages of different components and various structures to achieve superior electrochemical properties. Here, the branched nanocomposite with β‐MnO2 nanorods as the back‐bone and porous α‐Fe2O3 nanorods as the branches are synthesized by a high‐temperature annealing of FeOOH epitaxially grown on the β‐MnO2 nanorods. Since the β‐MnO2 nanorods grow along the four‐fold axis, the as‐produced branches of FeOOH and α‐Fe2O3 are aligned on their side in a nearly four‐fold symmetry. This synthetic process for the branched nanorods built by β‐MnO2/α‐Fe2O3 is characterized. The branched nanorods of β‐MnO2/α‐Fe2O3 present an excellent lithium‐storage performance. They exhibit a reversible specific capacity of 1028 mAh g−1 at a current density of 1000 mA g−1 up to 200 cycles, much higher than the building blocks alone. Even at 4000 mA g−1, the reversible capacity of the branched nanorods could be kept at 881 mAh g−1. The outstanding performances of the branched nanorods are attributed to the synergistic effect of different components and the hierarchical structure of the composite. The disclosure of the correlation between the electrochemical properties and the structure/component of the nanocomposites, would greatly benefit the rational design of the high‐performance nanocomposites for lithium ion batteries, in the future.
Upconversion Nanoparticles Conjugated with Gd3+‐DOTA and RGD for Targeted Dual‐Modality Imaging of Brain Tumor Xenografts
Authors: Jin Jiefu , Xu Zhenhua , Zhang Yue , Gu Yan‐Juan , Lam Michael Hon‐Wah , Wong Wing‐Tak
Published: April 2013

Glioblastoma multiforme (GBM) is the most common and malignant form of primary brain tumors in human. Small molecular magnetic resonance imaging (MRI) contrast agents are used for GBM diagnosis. However, conventional contrast agents have several limitations, such as low T1 relaxivity, short circulation half lives and absence of tumor targeting. Herein, we develop an upconversion nanoprobe labeled with Gd3+‐DOTA and RGD (UCNP‐Gd‐RGD) for dual‐modality imaging of glioblastoma. The preparation of UCNP‐Gd‐RGD starts with amine‐functional upconversion nanoparticle core, followed by PEGylation, Gd3+DOTA conjugation and RGD labeling. The obtained UCNP‐Gd‐RGD has improved colloidal stability and reduced cytotoxicity compared with the UCNP core counterpart. Meanwhile, UCNP‐Gd‐RGD shows strong upconversion luminescence in deep‐red region and three times enhancement of T1 relaxivity over Gd3+DOTA. Due to the recognition between UCNP‐Gd‐RGD and integrin αvβ3 receptors, the nanoprobe specifically binds to U87MG cells, as evidenced by confocal microscopy and quantified by ICP‐MS. Furthermore, UCNP‐Gd‐RGD demonstrates a preferential retention in subcutaneous U87MG tumor xenograft as shown in both in vivo upconversion fluorescence/MR imaging studies and ex vivo analysis. UCNP‐Gd‐RGD, conjugated with numerous RGD peptide and T1 contrast enhancing molecules, is promising for MR imaging of glioblastoma and delineating the tumor boundary before surgery. In addition, NIR‐to‐red upconversion characteristic of UCNP‐Gd‐RGD facilitates its potential intra‐operative use for fluorescence‐guided tumor resection.
Spondyloepimetaphyseal dysplasia Pakistani type: Expansion of the phenotype
Authors: Tüysüz Beyhan , Yılmaz Saliha , Gül Ece , Kolb Luis , Bilguvar Kaya , Evliyaoğlu Olcay , Günel Murat
Published: April 2013

Spondyloepimetaphyseal dysplasia (SEMD), Pakistani type, is a skeletal dysplasia characterized by platyspondyly, delayed epiphyseal ossification, mild metaphyseal abnormalities, short stature, and short and bowed legs, and is caused by mutations in PAPSS2. In a single Turkish patient also hyperandrogenism was reported. We describe five patients from a Turkish family with SEMD Pakistani type with homozygosity for a nonsense mutation (p.R329X) leading to a stop codon in PAPSS2. Plasma levels of dehydroepiandrosterone (DHEA) and androstenedione were normal, but DHEA sulfate levels were low in four of the patients. Two patients and a mother had history of pubertal hyperandrogenism. Testosterone level was mildly elevated in one of the female patients, and insulin resistance was not detected in any of the patients. The patients also had precocious costal calcification, small iliac bones, short femoral necks, coxa vara, short halluces and fused vertebral bodies, none of which has been reported previously in this entity. (c) 2013 Wiley Periodicals, Inc.
Screening and determination of drugs in human saliva utilizing microextraction by packed sorbent and liquid chromatography–tandem mass spectrometry
Authors: Abdel‐Rehim Abbi , Abdel‐Rehim Mohamed
Published: April 2013

This study presents a new method for collecting and handling saliva samples using an automated analytical microsyringe and microextraction by packed syringe (MEPS). The screening and determination of lidocaine in human saliva samples utilizing MEPS and liquid chromatography–tandem mass spectrometry (LC‐MS/MS) were carried out. An exact volume of saliva could be collected. The MEPS C8‐cartridge could be used for 50 extractions before it was discarded. The extraction recovery was about 60%. The pharmacokinetic curve of lidocaine in saliva using MEPS‐LC‐MS/MS is reported. Copyright © 2013 John Wiley & Sons, Ltd.
Occurrence and degree of intersex (testis–ova) in darters (Etheostoma SPP.) across an urban gradient in the Grand River, Ontario, Canada
Authors: Tanna Rajiv N. , Tetreault Gerald R. , Bennett Charles J. , Smith Brendan M. , Bragg Leslie M. , Oakes Ken D. , McMaster Mark E. , Servos Mark R.
Published: April 2013

The variability and extent of the intersex condition (oocytes in testes, or testis–ova) was documented in fish along an urban gradient in the Grand River, Ontario, Canada, that included major wastewater treatment plant outfalls. A method for rapid enumeration of testis–ova was developed and applied that increased the capacity to quantify intersex prevalence and severity. Male rainbow darters (Etheostoma caeruleum) sampled downstream of the first major wastewater outfall (Waterloo) had a significant increase, relative to 4 upstream reference sites, in the mean proportion of fish with at least 1 testis–oocyte per lobe of testes (9–20% proportion with ≤ 1 testis–oocyte/lobe vs 32–53% and >1.4 testis–oocyte/lobe). A much higher mean incidence of intersex proportion and degree was observed immediately downstream of the second wastewater outfall (Kitchener; 73–100% and 8–70 testis–oocyte/lobe); but only 6.3 km downstream of the Kitchener outfall, the occurrence of intersex dropped to those of the reference sites. In contrast, downstream of a tertiary treated wastewater outfall on a small tributary, intersex was similar to reference sites. Estrogenicity, measured using a yeast estrogen screen, followed a similar pattern, increasing from 0.81 ± 0.02 ng/L 17b-estradiol equivalents (EEq) (Guelph), to 4.32 ± 0.07 ng/L (Waterloo), and 16.99 ± 0.40 ng/L (Kitchener). Female rainbow darter downstream of the Kitchener outfall showed significant decreases in gonadosomatic index and liver somatic index, and increases in condition factor (k) relative to corresponding reference sites. The prevalence of intersex and alterations in somatic indices suggest that exposure to municipal wastewater effluent discharges can impact endocrine function, energy use, and energy storage in wild fish. Environ Toxicol Chem. 2013;32:1981–1991. © 2013 SETAC
Quantitative comparison of Taylor flow simulations based on sharp‐interface and diffuse‐interface models
Authors: Aland S. , Boden S. , Hahn A. , Klingbeil F. , Weismann M. , Weller S.
Published: April 2013

A pressure‐driven flow of elongated bullet‐shaped bubbles in a narrow channel is known as Taylor flow or bubble‐train flow. This process is of relevance in various applications of chemical engineering. In this paper, we describe a typical simplified experimental setting, with surface tension, density and viscosity as prescribed input parameters. We compare a sharp‐interface model based on a moving grid aligned with the bubble boundary (ALE coordinates) and a diffuse‐interface model where the bubble shape is implicitly given by a phase‐field function. Four independent implementations based on the two modeling approaches are introduced and described briefly. Besides the simulation of the bubble shapes, we compare some resulting quantities such as pressure difference and film widths within the implementations and to existing analytical and experimental results. The simulations were conducted in 2D and 3D (rotationally symmetric). Good accordance of the results indicate the applicability and the usability of all approaches. Differences between the models and their implementations are visible but in no contradiction to theoretical results. Copyright © 2013 John Wiley & Sons, Ltd.
NUP98‐NSD1 gene fusion and its related gene expression signature are strongly associated with a poor prognosis in pediatric acute myeloid leukemia
Authors: Shiba Norio , Ichikawa Hitoshi , Taki Tomohiko , Park Myoung‐Ja , Jo Aoi , Mitani Sachiyo , Kobayashi Tohru , Shimada Akira , Sotomatsu Manabu , Arakawa Hirokazu , Adachi Souichi , Tawa Akio , Horibe Keizo , Tsuchida Masahiro , Hanada Ryoji , Tsukimoto Ichiro , Hayashi Yasuhide
Published: April 2013

The cryptic t(5;11)(q35;p15.5) creates a fusion gene between the NUP98 and NSD1 genes. To ascertain the significance of this gene fusion, we explored its frequency, clinical impact, and gene expression pattern using DNA microarray in pediatric acute myeloid leukemia (AML) patients. NUP98‐NSD1 fusion transcripts were detected in 6 (4.8%) of 124 pediatric AML patients. Supervised hierarchical clustering analyses using probe sets that were differentially expressed in these patients detected a characteristic gene expression pattern, including 18 NUP98‐NSD1‐negative patients (NUP98‐NSD1‐like patients). In total, a NUP98‐NSD1‐related gene expression signature (NUP98‐NSD1 signature) was found in 19% (24/124) and in 58% (15/26) of cytogenetically normal cases. Their 4‐year overall survival (OS) and event‐free survival (EFS) were poor (33.3% in NUP98‐NSD1‐positive and 38.9% in NUP98‐NSD1‐like patients) compared with 100 NUP98‐NSD1 signature‐negative patients (4‐year OS: 86.0%, 4‐year EFS: 72.0%). Interestingly, t(7;11)(p15;p15)/NUP98‐HOXA13, t(6;11)(q27;q23)/MLL‐MLLT4 and t(6;9)(p22;q34)/DEK‐NUP214, which are known as poor prognostic markers, were found in NUP98‐NSD1‐like patients. Furthermore, another type of NUP98‐NSD1 fusion transcript was identified by additional RT‐PCR analyses using other primers in a NUP98‐NSD1‐like patient, revealing the significance of this signature to detect NUP98‐NSD1 gene fusions and to identify a new poor prognostic subgroup in AML. © 2013 Wiley Periodicals, Inc.
Polarized distribution of AMPA, but not GABAA, receptors in radial glia‐like cells of the adult dentate gyrus
Authors: Renzel Roland , Sadek Ahmed‐Ramadan , Chang Cin‐He , Gray William P. , Seifert Gerald , Steinhäuser Christian
Published: April 2013

Glial fibrillary acidic protein (GFAP)‐positive astrocytes with radial processes [radial glia (RG)‐like cells] in the postnatal dentate gyrus share many of the characteristics of embryonic radial glia and appear to act as precursor cells for adult dentate neurogenesis, a process important for pattern separation and hippocampus‐dependent learning. Although much work has delineated the mechanisms underlying activity‐neurogenesis coupling via gamma‐amino butyric acid (GABA)ergic neurotransmission on GFAP‐negative transient‐amplifying cells and neuroblasts, little is known regarding the effects of neurotransmitters on RG‐like cells. Conflicting evidence exists for both GABA and glutamate receptors on these cells. Here, using GFAP reporter mice, we show that the somatic membrane of RG‐like cells carries GABAA receptors and glutamate transporters but not ionotropic glutamate receptors, whereas 2‐amino‐3‐(hydroxyl‐5‐methylisoxazole‐4‐yl) propionic acid (AMPA) and GABAA receptors are expressed on the processes of these cells. Almost all RG‐like cells expressed the GluA2 subunit, which restricts the Ca2+ permeability of AMPA receptors. The glial GABAA receptors mainly comprised α2/α4, β1, and γ1/γ3. The selective presence of AMPA receptors on the radial processes may be important for sensing and responding to local activity‐driven glutamate release and supports the concept that RG‐like astrocytes are composed of functional and structural domains.
Population‐based evaluation of incidence trends in oropharyngeal cancer focusing on socioeconomic status, sex, and race/ethnicity
Authors: Colevas A. Dimitrios
Published: April 2013

Background

The influences of socioeconomic status (SES) on the incidence rates of oropharyngeal squamous cell carcinoma (OPSCC) are unclear.

Methods

Data from the California Cancer Registry and U.S. Census were used to compare incidence rates and trends of OPSCC and other human papillomavirus–related and –unrelated cancer sites by neighborhood SES, race/ethnicity, and sex.

Results

The incidence of OPSCC rose in both higher and lower SES neighborhoods. Absolute rates were greater in the latter. Only non‐Hispanic white males with OPSCC demonstrated a significant increase in the incidence rate of squamous cell carcinoma of the head and neck (SCCHN). The incidence rate for this group increased from 4.5/100,000 person‐years between 1988 and 1992 to 7.1 between 2003 and 2009. Regression analysis demonstrated an annual percentage change of 1% from 1988 to 1997 and 4% thereafter.

Conclusions

Increases in incidence rates are SES independent. Incidence rates are higher in lower‐SES groups. The rise in OPSCC incidence is limited to non‐Hispanic white males. © 2013 Wiley Periodicals, Inc. Head Neck 36: 34–42, 2014
Radiotherapy for a repeatedly recurrent ameloblastoma with malignant transformation
Authors: Huang Chun‐Ming , Chen Jin‐Yi , Chen Chung‐Ho , Huang Chih‐Jen
Published: April 2013

Background

The role of radiation therapy (RT) for ameloblastoma remains controversial and undetermined due to the rarity of the disease.

Methods

A case of repeatedly recurrent ameloblastoma with malignant transformation is presented. The clinical course and managements are described.

Results

The 63‐year‐old man had a recurrent ameloblastoma in the left mandible. Five years after the first surgical resection, he underwent 8 more rounds of surgical excision of the recurrent tumors. The malignant transformation occurred and the unresectable tumor invaded the masticator space, parapharyngeal space, and skull base. He received 3‐dimensional conformal RT, at the dose of 66 Gray (Gy) in 33 fractions. The ulcerative exophytic mass had regressed gradually. After follow‐up of 28 months, the tumor was well controlled.

Conclusions

RT seems to be a feasible treatment option for recurrent ameloblastoma with malignant transformation. © 2013 Wiley Periodicals, Inc. Head Neck 36: E1–E3, 2014
Muscle size, strength, and physical performance and their associations with bone structure in the Hertfordshire Cohort Study
Authors: Edwards Mark H , Gregson Celia L , Patel Harnish P , Jameson Karen A , Harvey Nicholas C , Sayer Avan Aihie , Dennison Elaine M , Cooper Cyrus
Published: April 2013

Sarcopenia is associated with a greater fracture risk. This relationship was originally thought to be explained by an increased risk of falls in sarcopenic individuals. However, in addition, there is growing evidence of a functional muscle-bone unit in which bone health may be directly influenced by muscle function. Because a definition of sarcopenia encompasses muscle size, strength, and physical performance, we investigated relationships for each of these with bone size, bone density, and bone strength to interrogate these hypotheses further in participants from the Hertfordshire Cohort Study. A total of 313 men and 318 women underwent baseline assessment of health and detailed anthropometric measurements. Muscle strength was measured by grip strength, and physical performance was determined by gait speed. Peripheral quantitative computed tomography (pQCT) examination of the calf and forearm was performed to assess muscle cross-sectional area (mCSA) at the 66% level and bone structure (radius 4% and 66% levels; tibia 4% and 38% levels). Muscle size was positively associated with bone size (distal radius total bone area β = 17.5 mm2/SD [12.0, 22.9]) and strength (strength strain index (β = 23.3 mm3/SD [18.2, 28.4]) amongst women (p < 0.001). These associations were also seen in men and were maintained after adjustment for age, height, weight-adjusted-for-height, limb-length-adjusted-for-height, social class, smoking status, alcohol consumption, calcium intake, physical activity, diabetes mellitus, and in women, years since menopause and estrogen replacement therapy. Although grip strength showed similar associations with bone size and strength in both sexes, these were substantially attenuated after similar adjustment. Consistent relationships between gait speed and bone structure were not seen. We conclude that although muscle size and grip strength are associated with bone size and strength, relationships between gait speed and bone structure and strength were not apparent in this cohort, supporting a role for the muscle-bone unit. © 2013 American Society for Bone and Mineral Research
Chemiluminescence Determination of Gossypol by Oxidation with N‐Bromosuccinimide
Authors: Han Suqin , Hao Fang , Wei Bei
Published: April 2013

A chemiluminescence (CL) phenomenon was observed when gossypol was injected into a reaction mixture of N‐bromosuccinimide (NBS) and alkaline dichlorofluorescein (DCF). Based on this phenomenon, a rapid and sensitive method for the determination of gossypol was established. Under the optimum conditions, the linear range was from 1.0 × 10−9 to 1.0 × 10−6 M. The detection limit was 1.0 × 10−10 M. The method has been applied to the determination of gossypol in cottonseed, cottonseed oil, pharmaceutical and biological fluids with satisfactory results. The possible CL reaction mechanism was discussed briefly.
Determination of Diuretics in Urine Using Immobilized Multi‐Walled Carbon Nanotubes in Hollow Fiber Liquid‐Phase Microextraction Combined with Liquid Chromatography‐Tandem Mass Spectrometry
Authors: Ho Tse‐Tsung , Li Zu‐Guang , Lin Hui‐Yi , Lee Maw‐Rong
Published: April 2013

A novel technique utilizing the adsorptive potential of immobilized multi‐walled carbon nanotubes (I‐MWCNT) in hollow fiber liquid‐phase microextraction (HF‐LPME) was developed for the determination of diuretics in urine. In this study, the potential of carbon nanotubes as a sorbent for three‐phase liquid‐phase microextraction of diuretics from urine samples was evaluated. Analysis was performed using liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). A novel method was applied to detect acetazolamide (AAA), chlorothiazide (CTA), hydrochlorothiazide (HCT), hydroflumethiazide (HFT), clopamide (CA), trichlormethiazide (TCM), althiazide (AT) and bendroflumethiazide (BFT) in urine. Two‐step extractions using different times and temperatures for each step were adopted. Parameters influencing the extraction efficiency, including the extraction solvent, sample pH, salt concentration, extraction time and extraction temperature were systematically optimized. Under the resulting optimal extraction conditions, this method showed good linearity over an analytes concentration range of 1 to 1000 ng/mL, high extraction repeatability with relative standard deviations of less than 6%, and low detection limits (0.09 to 0.51 ng/mL). The application of the methods to the determination of diuretics in real samples was tested by analyzing urine samples of patient.
Development of a Sensitive Method for the Determination of 4‐(Methylnitrosamino)‐1‐(3‐pyridyl)‐1‐butanol in Human Urine Using Solid‐phase Extraction Combined with Ultrasound‐assisted Dispersive Liquid–liquid Microextraction and LC‐MS/MS Detection
Authors: Liu Bai‐Zhan , Yao Li , Zheng Sai‐Jing , Wang Wei‐Miao , Zhu Xiao‐Lan , Yang Jun
Published: April 2013

An efficient and sensitive analytical method based on molecularly imprinted solid‐phase extraction (MISPE) and reverse‐phase ultrasound‐assisted dispersive liquid–liquid microextraction (USA‐DLLME) coupled with LC–MS/MS detection was developed and validated for the analysis of urinary 4‐(methylnitrosamino)‐1‐(3‐pyridyl)‐1‐butanol (NNAL), a tobacco‐specific nitrosamine metabolite. The extraction performances of NNAL on three different solid‐phase extraction (SPE) sorbents including the hydrophilic‐lipophilic balanced sorbent HLB, the mixed mode cationic MCX sorbent and the molecularly imprinted polymers (MIP) sorbent were evaluated. Experimental results showed that the analyte was well retained with the highest extraction recovery and the optimum purification effect on MIP. Under the optimized conditions of MIP and USA‐DLLME, an enrichment factor of 23 was obtained. Good linearity relationship was obtained in the range of 5‐1200 pg/mL with a correlation coefficient of 0.9953. The limit of detection (LOD) was 0.35 pg/mL. The recoveries at three spiked levels ranged between 88.5% and 93.7%. Intra‐ and inter‐day relative standard deviations varied from 3.6% to 7.4% and from 5.4% to 9.7%, respectively. The developed method combing the advantages of MISPE and DLLME significantly improves the purification and enrichment of the analyte and can be used as an effective approach for the determination of ultra‐trace NNAL in complex biological matrices.
Gaseous and Particle‐bound VOC Products of Combustion Extracted by Needle Trap Samplers
Authors: Cheng Wen‐Hsi , Zhan Weiqiang , Pawliszyn Janusz
Published: April 2013

Gaseous benzene, toluene, ethylbenzene and o‐xylene (BTEX) were extracted by using the divinylbenzene (DVB) particles (mesh sizes 60–80, 80–100 and 100–120) as sorbents packed in passive needle trap samplers (NTS). This study performed feasibility tests of these self‐designed DVB‐NTS as diffusive time‐weighted average (TWA) samplers and compared extraction efficiency with that of 100 mm polydimethylsiloxane‐solid phase microextration (PDMS‐SPME) fiber for sampling gaseous and particle‐bound volatile organic compounds (VOCs) from burning mosquito coils. Experimental results indicated that extraction rate of NTS is a reliable index in extracting VOCs. Additionally, comparisons of the NTS in extracting BTEX mass showed the NTS packed with the smallest diameters of adsorbent particles (100–120 mesh DVB) were the most effective. The mass of gaseous BTEX extracted by 100 μm PDMS‐SPME fiber were substantially lower than that extracted by DVB‐NTS of all meshes for the 30‐min TWA sampling of burning mosquito coils, and NTS packed with 100–120 mesh DVB adsorbed BTEX 50–120 ng BTEX. Particles clogging inside the packed phase of NTS inhibited VOC extraction performance after 3–5 samplings of burning particles, especially NTS packed with small‐diameter adsorbents.
Simultaneous Determination Baicalin and Forsythin in Shuanghuanglian Oral Liquid by HPLC/DAD and LC‐ESI‐MS
Authors: Yang Li , Yan Qing‐hua , Yu Juan , Zhang Jian‐wei , Xi Guoxi
Published: April 2013

Rapid, simple and reliable HPLC/DAD and LC‐ESI‐MS methods for the simultaneous determination of baicalin and forsythin in the traditional Chinese medicinal preparation Shuanghuanglian oral liquid were described and validated. The separation condition for HPLC/DAD was optimized using a BDS hypersil C18 column (Thermo, 2.1 × 150 mm, particle size 5 μm) by gradient elution using methanol‐0.2 % ammonium acetate as the mobile phase. The suitable detection wavelength was set at 277 nm for the quantitative analysis of baicalin and forsythin in this method. Some operational parameters of the ESI interface were optimized, negative m/z 445[M−H]− for baicalin and negative m/z 593[M+CH3COO]− for forsythin, positive m/z 447[M+H]+ for baicalin and positive m/z 552[M+NH 4]+ for forsythin, respectively. These HPLC/DAD and LC‐ESI‐MS methods were validated in terms of recovery, linearity, accuracy and precision (intra‐ and inter‐day validation). These methods can be used as a complementary method for the commercial quality control of Shuanghuanglian oral liquid and its pharmaceutical preparations.
Graphene‐Nafion Composite Film Modified Electrode for Voltammetric Sensor for Determination of Dihydromyricetin
Authors: Wang Fei , Yu Xiang , Li Haojie , Li Ming , Feng Qimin
Published: April 2013

A simple but highly snesitive electrochemical sensor for the determination of dihydromyricetin (DMY) based on graphene‐Nafion nanocomposite film modified Glassy carbon electrode (GCE) was reported. The characteristic of the sensor was examined by scanning electron microscopic (SEM) and electrochemical impedance spectroscopy (EIS). Compares with bare GCE, pre‐anodized glassy carbon electrode (GCE(ox)) and Nafion modified electrode, the sensor exhibited the more superior ability of detecting DMY, due to the synergetic graphene and Nafion. Other, the dependence of the current on pH, instrumental parameters, accumulation time and potential were investigated to optimize the experimental conditions in the determination of DMY. Under the selected conditions, the response peak currents were linear relationship with the DMY concentrations in the range of 8.0 × 10−8 ∼ 2.0 × 10−5 mol L−1 with a detection limit of 2.0 × 10−8 mol L−1. And, the method was also applied successfully to detect DMY in Ampelopsis grossedentata samples.
Novel applications of dividing‐wall column technology to biofuel production processes
Authors: Kiss Anton A.
Published: April 2013

Biofuels enjoy nowadays increased public and scientific attention, driven by key factors such as volatile oil price, the need for increased energy security, and concerns over greenhouse gas emissions from fossil fuels. However, in order to make biofuels a competitive alternative, the cost of production has to be significantly reduced by using enhanced process technologies. Distillation is heavily involved in the production processes of biofuels—taking the blame for the high energy requirements that have a negative impact on the operating costs. Dividing‐wall column (DWC) is one of the best examples of proven industrial process intensification technology in distillation, as it allows significantly lower investment and operating costs while also reducing the number of equipment units and the carbon footprint.

This work presents an overview of novel applications using the DWC technology in the production of the most important biofuels, by employing multi‐component separations, azeotropic, extractive or reactive distillation in a DWC: enhanced methanol recovery and glycerol separation in biodiesel production, synthesis of fatty acid methyl esters and dimethyl ether (DME) by reactive distillation, integrated DME purification and methanol or CO2 recovery in the dimethyl ether process, as well as bioethanol concentration and dehydration. The industrially relevant case studies presented here show that significant energy savings are possible (ranging from ∼20 to 60%) while simplifying the processes by using less equipment that requires a lower plant footprint. Remarkably, in most cases there is also the possibility of revamping existing plants producing biofuels, and thus reusing the already available equipment. © 2013 Society of Chemical Industry
Mass removal and clay mineral dehydration/rehydration in carbonate‐rich surface exposures of the 2008 Wenchuan Earthquake fault: Geochemical evidence and implications for fault zone evolution and coseismic slip
Authors: Chen Jianye , Yang Xiaosong , Ma Shengli , Spiers Christopher J.
Published: April 2013

We report variations in the mineralogical, geochemical, and isotopic (δ13C, δ18O) composition of fault rocks sampled in transects across the Zhaojiagou and Pingxi exposures of the Wenchuan Earthquake or Longmenshan Fault Zone, where the gouge‐rich fault core and principal slip surface cuts through carbonate‐rich strata. Pervasive fluid infiltration was found to modify the mineralogical and geochemical architecture of the fault zones studied. Enrichment/depletion patterns, element partitioning, and a very large implied volume loss are quite different from those characterizing faults in granites and clastic sedimentary rocks and can be explained by a mass removal model involving dissolution and advective transport enhanced by pressure solution. An increasing enrichment in smectite observed toward the principal slip surface, a high abundance of elements such as Ba, Mg, and F, the deposition of minerals such as barite and fluorapatite, as well as the distinct depletion in 13C in vein material consistently suggest reactions involving a hydrothermal fluid originating at depth. Illitization of black gouges, caused by coseismic frictional heating, was found to be widespread. We propose that coseismic frictional heating along with the action of postseismic hydrothermal fluids controlled the transformation and distribution of smectite and illite within the fault core of the Longmenshan Fault Zone. The coseismic dewatering reactions are expected to have been more extensive at depth, possibly helping generate excess pore pressure assisting dynamic slip weakening during the Wenchuan Earthquake.
Is biological productivity enhanced at the New England shelfbreak front?
Authors: Zhang Weifeng G. , McGillicuddy Dennis J. , Gawarkiewicz Glen G.
Published: April 2013

A two‐dimensional (cross‐shelf) numerical model of the mean seasonal circulation offshore of southern New England predicts upwelling at the shelfbreak front. Expected ramifications of this upwelling include enhancement of nutrient supply, phytoplankton biomass, and productivity. However, seasonal climatologies of chlorophyll based on both in situ data and satellite observations show no mean enhancement at the front. We investigate this apparent discrepancy with a four‐component planktonic ecosystem model coupled to the two‐dimensional physical model. Nutrient fields are restored to climatological values at depth, and upper ocean values evolve freely according to physical and biological forcing. Vertical diffusivity is based on seasonally averaged surface and bottom mixed layer depths compiled from in situ observations. The model reproduces the general pattern of the observed cross‐shelf and seasonal variations of the chlorophyll distribution. It predicts a local enhancement of phytoplankton productivity at the shelfbreak in spring and summer as a result of the persistently upwelled nutrient‐rich slope water. In the model, zooplankton grazing prevents accumulation of phytoplankton biomass at the site of the upwelling. The predicted enhancement of primary productivity (but not phytoplankton biomass) at the shelfbreak constitutes a hypothesis that could be tested in the future with suitable measurements from regional long‐term observatories, such as the Ocean Observatories Initiative Pioneer Array.
Global ocean surface velocities from drifters: Mean, variance, El Niño–Southern Oscillation response, and seasonal cycle
Authors: Lumpkin Rick , Johnson Gregory C.
Published: April 2013

Global near‐surface currents are calculated from satellite‐tracked drogued drifter velocities on a 0.5° × 0.5° latitude‐longitude grid using a new methodology. Data used at each grid point lie within a centered bin of set area with a shape defined by the variance ellipse of current fluctuations within that bin. The time‐mean current, its annual harmonic, semiannual harmonic, correlation with the Southern Oscillation Index (SOI), spatial gradients, and residuals are estimated along with formal error bars for each component. The time‐mean field resolves the major surface current systems of the world. The magnitude of the variance reveals enhanced eddy kinetic energy in the western boundary current systems, in equatorial regions, and along the Antarctic Circumpolar Current, as well as three large “eddy deserts,” two in the Pacific and one in the Atlantic. The SOI component is largest in the western and central tropical Pacific, but can also be seen in the Indian Ocean. Seasonal variations reveal details such as the gyre‐scale shifts in the convergence centers of the subtropical gyres, and the seasonal evolution of tropical currents and eddies in the western tropical Pacific Ocean. The results of this study are available as a monthly climatology.
Oceanographic observations at the shelf break of the Amundsen Sea, Antarctica
Authors: Walker Dziga P. , Jenkins Adrian , Assmann Karen M. , Shoosmith Deborah R. , Brandon Mark A.
Published: April 2013

The glaciers draining into the Amundsen Sea Embayment are rapidly losing mass, making a significant contribution to current sea level rise. Studies of Pine Island Glacier (PIG) in this region indicate that the mass loss is associated with rapid melting of its floating ice shelf driven by warm Circumpolar Deep Water (CDW) that is able to penetrate all the way to its grounding line, and that recent intensification of the mass loss is associated with higher melt rates and stronger subice‐shelf circulation. CDW is sourced from within the Antarctic Circumpolar Current (ACC) situated well north of the glacial ice fronts. To be able to access the Amundsen Sea glaciers, CDW must first cross the continental shelf break where the deep ocean meets the shallower waters of the continental shelf. Here, we present data that shows how CDW moves along the continental slope and across the shelf break into the Amundsen Sea. On‐shelf flow of CDW is enhanced where a subsea trough bisects the shelf edge. A previously unreported undercurrent is observed flowing eastward along the shelf edge and when this current encounters the trough mouth it circulates southward into the trough and toward the glaciers. Upwelling associated with this trough circulation appears to allow Lower CDW onto the shelf that would otherwise be blocked by the topography. These observations concur with the results of a theoretical modeling study of circulation in a similar topographic setting and also with the results of a regional ocean/ice modeling study of the Amundsen Sea specifically.
The role of circulation features on black carbon transport into the Arctic in the Community Atmosphere Model version 5 (CAM5)
Authors: Ma Po‐Lun , Rasch Philip J. , Wang Hailong , Zhang Kai , Easter Richard C. , Tilmes Simone , Fast Jerome D. , Liu Xiaohong , Yoon Jin‐Ho , Lamarque Jean‐Francois
Published: April 2013

Current climate models generally underpredict the surface concentration of black carbon (BC) in the Arctic due to the uncertainties associated with emissions, transport, and removal. This bias is also present in the Community Atmosphere Model version 5.1 (CAM5). In this study, we investigate the uncertainty of Arctic BC due to transport processes simulated by CAM5 by configuring the model to run in an “off‐line mode” in which the large‐scale circulation features are prescribed. We compare the simulated BC transport when the off‐line model is driven by the meteorology predicted by the standard free‐running CAM5 with simulations where the meteorology is constrained to agree with reanalysis products. Some circulation biases are apparent: the free‐running CAM5 produces about 50% less transient eddy transport of BC than the reanalysis‐driven simulations, which may be attributed to the coarse model resolution insufficient to represent eddies. Our analysis shows that the free‐running CAM5 reasonably captures the essence of the Arctic Oscillation (AO), but some discernable differences in the spatial pattern of the AO between the free‐running CAM5 and the reanalysis‐driven simulations result in significantly different AO modulation of BC transport over northeast Asia and eastern Europe. Nevertheless, we find that the overall climatological circulation patterns simulated by the free‐running CAM5 generally resemble those from the reanalysis products, and BC transport is very similar in both simulation sets. Therefore, the simulated circulation features regulating the long‐range BC transport are unlikely the most important cause of the large underprediction of surface BC concentration in the Arctic.
Experimental delta formation in crater lakes and implications for interpretation of Martian deltas
Authors: de Villiers Germari , Kleinhans Maarten G. , Postma George
Published: April 2013

The morphology of delta deposits in crater lakes on Mars is indicative of upstream (e.g., flow discharge and sediment properties) and downstream (e.g., basin characteristics) parameters, from which the hydrological conditions at the time of formation can be inferred. To investigate the influences of these parameters on delta morphology, we experimentally created deltas in crater‐shaped basins by feeding a range of constant flow discharges over a feeder channel of various sand textures. We reproduced three categorically different types of deltas including most of the types that have been identified on Mars. Our most striking observation is that water level behavior (itself a unique function of flow discharge, basin size and hypsometry, and basin floor permeability) can explain most delta morphologies observed on Mars. Stepped, retrograding deltas formed during water level rise, prograding deltas formed during water level still stand, and during water level fall deltas were partially destroyed by erosion. On Mars numerous retrograding and prograding deltas were preserved, most of them without indications of channel incisions or other fluvial modification. We conclude that the main difference between a single‐foreset prograding delta and a multiple‐foreset retrograding delta is the behavior of the water level in the basin. These simple delta morphologies cannot be reconciled with long‐duration hydrological activity, because that would imply crater lake fluctuations due to inherent complex water level histories along with complex sediment delivery histories. Our experiments and numerical verifications demonstrate that such deltas preferentially form during one aqueous event, which parsimoniously argues for short‐duration hydrological activity.
Magnetodynamo lifetimes for rocky, Earth‐mass exoplanets with contrasting mantle convection regimes
Authors: van Summeren Joost , Gaidos Eric , Conrad Clinton P.
Published: April 2013

We used a thermal model of an iron core to calculate magnetodynamo evolution in Earth‐mass rocky planets to determine the sensitivity of dynamo lifetime and intensity to planets with different mantle tectonic regimes, surface temperatures, and core properties. The heat flow at the core‐mantle boundary (CMB) is derived from numerical models of mantle convection with a viscous/pseudoplastic rheology that captures the phenomenology of plate‐like tectonics. Our thermal evolution models predict a long‐lived (~8 Gyr) field for Earth and similar dynamo evolution for Earth‐mass exoplanets with plate tectonics. Both elevated surface temperature and pressure‐dependent mantle viscosity reduce the CMB heat flow but produce only slightly longer‐lived dynamos (~8–9.5 Gyr). Single‐plate (“stagnant lid”) planets with relatively low CMB heat flow produce long‐lived (~10.5 Gyr) dynamos. These weaker dynamos can cease for several billions of years and subsequently reactivate due to the additional entropy production associated with inner core growth, a possible explanation for the absence of a magnetic field on present‐day Venus. We also show that dynamo operation is sensitive to the initial temperature, size, and solidus of a planet's core. These dependencies would severely challenge any attempt to distinguish exoplanets with plate tectonics and stagnant lids based on the presence or absence of a magnetic field.
Convection‐driven compaction as a possible origin of Enceladus's long wavelength topography
Authors: Besserer J. , Nimmo F. , Roberts J. H. , Pappalardo R. T.
Published: April 2013

The long wavelength surface topography of Enceladus shows depressions about 1 km in depth and ∼102 km wide. One possible cause of this topography is spatially variable amounts of compaction of an initially porous ice shell, driven by spatial variations in heat flux. Here, we show that the heat flux variations associated with convection in the shell can quantitatively match the observed features. We develop a simple model of viscous compaction that includes the effect of porosity on thermal conductivity, and find that an initial shell porosity of at least 20–25% is required to develop the observed topography over ∼1 Ga. This mechanism produces topographic depressions, not rises, above convective upwellings, and does not generate detectable gravity anomalies. Unlike transient dynamic topography, it can potentially leave a permanent record of ancient convective processes in the shallow lithospheres of icy satellites.
Direct detection of chlorpropham on potato skin using desorption electrospray ionization
Authors: Berchtold Christian , Müller Vivian , Meier Lukas , Schmid Stefan , Zenobi Renato
Published: April 2013

Most pesticides, herbicides and other plant treatment agents are applied to the crop surface. Direct mass spectrometric methods, such as desorption electrospray ionization (DESI), offer new ways to analyze plant samples directly and rapidly. A strategy for the development and optimization of a DESI method for the direct determination of chemicals on complex surfaces is described. Chlorpropham (CP) was applied to potato surfaces as an example for a crop protection agent and analyzed using a self‐made DESI source. Aspects such as instrument selectivity, sensitivity and reproducibility were investigated. The MS4 fragmentation pattern of CP was analyzed to achieve the necessary detection selectivity, and is discussed in detail. Similar fragmentation was found in the ESI and DESI mass spectra, indicating that the mechanisms of ESI and DESI are closely related. A DESI method for semi‐quantification of CP on potatoes was developed. Detection limits of 6.5 µg/kg were found using MS/MS. The reproducibility, in the range of 12% (signal variation), appears to be sufficient for semi‐quantitative measurements. Copyright © 2013 John Wiley & Sons, Ltd.