bluuebunny/crossref_metadata_2025 huggingface dataset:
Challenging limits: Ultrastructure and size‐related functional constraints of the compound eye of Stigmella microtheriella (Lepidoptera: Nepticulidae)
Authors: Fischer Stefan , Meyer‐Rochow V. Benno , Müller Carsten H. G.
Published: June 2012

With a body length of only 2 mm, the nepticulid Stigmella microtheriella (Stainton, 1854) is one of the smallest moths known to date. We investigated the optical design of its lemon‐shaped compound eyes, which measure 83.60 μm in anterior–posterior and 119.77 μm in dorso‐ventral direction. The eyes consist of about 123 facets, each of the latter just 9.9 μm in diameter. Transmission electron microscopy reveals an optical design with features intermediate between apposition and superposition optics similar to that known from two other small species of moths (one Nepticulid and one Gracillarid). Size‐related evolutionary adaptations of the ommatidial organization include (1) the involvement of only five rhabdomeres in the formation of the distal rhabdom (2) the complete absence of a rhabdomere of the eighth (= basal) retinula cell, (3) the “hourglass” shape of the rhabdom with a characteristic narrow waist separating distal from proximal portion, and (4) the reduction to one single layer of tracheoles as an adaptation to the overall restricted space available in this minute eye. J. Morphol. 2012. © 2012 Wiley Periodicals, Inc.
Scaling of the ballistic tongue apparatus in chameleons
Authors: Anderson Christopher V. , Sheridan Thomas , Deban Stephen M.
Published: June 2012

Body dimensions of organisms can have a profound impact on their functional and structural properties. We examined the morphological proportions of the feeding apparatus of 105 chameleon specimens representing 23 species in seven genera, spanning a 1,000‐fold range in body mass to test whether the feeding apparatus conforms to the null hypotheses of geometric similarity that is based on the prevalence of geometric similarity in other ectothermic vertebrates. We used a phylogenetically corrected regression analysis based on a composite phylogenetic hypothesis to determine the interspecific scaling patterns of the feeding apparatus. We also determined the intraspecific (ontogenetic) scaling patterns for the feeding apparatus in three species. We found that both intraspecifically and interspecifically, the musculoskeletal components of the feeding apparatus scale isometrically among themselves, independent of body length. The feeding apparatus is thus of conserved proportions regardless of overall body length. In contrast, we found that the tongue apparatus as a whole and its musculoskeletal components scale with negative allometry with respect to snout‐vent length—smaller individuals have a proportionately larger feeding apparatus than larger individuals, both within and among species. Finally, the tongue apparatus as a whole scales with negative allometry with respect to body mass through ontogeny, but with isometry interspecifically. We suggest that the observed allometry may be maintained by natural selection because an enlarged feeding apparatus at small body size may maximize projection distance and the size of prey that smaller animals with higher mass‐specific metabolic rates can capture. J. Morphol. 2012. © 2012 Wiley Periodicals, Inc.
Evaluation of sampling density on the accuracy of aortic pulse wave velocity from velocity‐encoded MRI in patients with Marfan syndrome
Authors: Kröner Eleanore S.J. , van der Geest Rob J. , Scholte Arthur J.H.A. , Kroft Lucia J.M. , van den Boogaard Pieter J. , Hendriksen Dennis , Lamb Hildo J. , Siebelink Hans‐Marc J. , Mulder Barbara J.M. , Groenink Maarten , Radonic Teodora , Hilhorst‐Hofstee Yvonne , Bax Jeroen J. , van der Wall Ernst E. , de Roos Albert , Reiber Johan H.C. , Westenberg Jos J.M.
Published: June 2012

Purpose:

To evaluate the effect of spatial (ie, number of sampling locations along the aorta) and temporal sampling density on aortic pulse wave velocity (PWV) assessment from velocity‐encoded MRI in patients with Marfan syndrome (MFS).

Materials and Methods:

Twenty‐three MFS patients (12 men, mean age 36 ± 14 years) were included. Three PWV‐methods were evaluated: 1) reference PWVi.p. from in‐plane velocity‐encoded MRI with dense temporal and spatial sampling; 2) conventional PWVt.p. from through‐plane velocity‐encoded MRI with dense temporal but sparse spatial sampling at three aortic locations; 3) EPI‐accelerated PWVt.p. with sparse temporal but improved spatial sampling at five aortic locations with acceleration by echo‐planar imaging (EPI).

Results:

Despite inferior temporal resolution, EPI‐accelerated PWVt.p. showed stronger correlation (r = 0.92 vs. r = 0.65, P = 0.03) with reference PWVi.p. in the total aorta, with less error (8% vs. 16%) and variation (11% vs. 27%) as compared to conventional PWVt.p.. In the aortic arch, correlation was comparable for both EPI‐accelerated and conventional PWVt.p. with reference PWVi.p. (r = 0.66 vs. r = 0.67, P = 0.46), albeit 92% scan‐time reduction by EPI‐acceleration.

Conclusion:

Improving spatial sampling density by adding two acquisition planes along the aorta results in more accurate PWV assessment, even when temporal resolution decreases. For regional PWV assessment in the aortic arch, EPI‐accelerated and conventional PWV assessment are comparably accurate. Scan‐time reduction makes EPI‐accelerated PWV assessment the preferred method of choice. J. Magn. Reson. Imaging 2012; 36:1470–1476. © 2012 Wiley Periodicals, Inc.
Greater muscle co‐contraction results in increased tibiofemoral compressive forces in females who have undergone anterior cruciate ligament reconstruction
Authors: Tsai Liang‐Ching , McLean Scott , Colletti Patrick M. , Powers Christopher M.
Published: June 2012

Individuals who have undergone ACL reconstruction (ACLR) have been shown to have a higher risk of developing knee osteoarthritis (OA). The elevated risk of knee OA may be associated with increased tibiofemoral compressive forces. The primary purpose of this study was to examine whether females with ACLR demonstrate greater tibiofemoral compressive forces, as well as greater muscle co‐contraction and decreased knee flexion during a single‐leg drop‐land task when compared to healthy females. Ten females with ACLR and 10 healthy females (control group) participated. Each participant underwent two data collection sessions: (1) MRI assessment and (2) biomechanical analysis (EMG, kinematics, and kinetics) during a single‐leg drop‐land task. Joint kinematics, EMG, and MRI‐measured muscle volumes and patella tendon orientation were used as input variables into a MRI‐based EMG‐driven knee model to quantify the peak tibiofemoral compressive forces during landing. Peak tibiofemoral compressive forces were significantly higher in the ACLR group when compared to the control group (97.3 ± 8.0 vs. 88.8 ± 9.8 N · kg−1). The ACLR group also demonstrated significantly greater muscle co‐contraction as well as less knee flexion than the control group. Our findings support the premise that individuals with ACLR demonstrate increased tibiofemoral compression as well as greater muscle co‐contraction and decreased knee flexion during a drop‐land task. Future studies are needed to examine whether correcting abnormal neuromuscular strategies and reducing tibiofemoral compressive forces following ACLR can slow the progression of joint degeneration in this population. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:2007–2014, 2012
Complex PTSD is on the trauma spectrum: Comment on Resick et al. (2012)
Authors: Goodman Marianne
Published: June 2012

Conceptualizing posttraumatic stress disorder (PTSD) along a spectrum with complex and simple features is integrative and models an approach taken by disciplines in medicine outside of psychiatry. This perspective is offered in the Resick et al. (2012) review. To best delineate the nature and permeability of the border between Complex PTSD and PTSD, an emphasis on clarifying underlying biological processes is needed to move beyond our current reliance on symptomatic description.
Benefit Finding at War: A Matter of Time
Authors: Wood Michael D. , Britt Thomas W. , Wright Kathleen M. , Thomas Jeffrey L. , Bliese Paul D.
Published: June 2012

Benefit finding, described as one's ability to find benefits from stressful situations, has been hypothesized as a buffer against the negative effects of stress on mental health outcomes. Nonetheless, many have questioned the buffering potential of benefit finding in the face of prolonged and excessive stress such as is found in the combat environment. This study suggests that the length of a combat deployment and benefit finding may impact the relationship between combat exposure and posttraumatic stress disorder (PTSD) symptoms. Surveys were distributed to U.S. enlisted soldiers (n = 1,917), officers, and warrant officers (n = 163) of various combat and combat support units deployed to Iraq. A significant 3‐way interaction (sr2 = .004, p < .05) revealed that benefit finding buffered soldiers from increased PTSD symptoms under high levels of combat exposure early in the deployment, but not in later months. These results indicate that although benefit finding may be a useful coping approach during the early phases of deployment, prolonged exposure to stress may diminish a soldier's ability to use benefit finding as a method for coping.
Use of higher thromboelastogram transfusion values is not associated with greater blood loss in liver transplant surgery
Authors: Wang Shen-Chih , Lin Ho-Tien , Chang Kuang-Yi , Mandell Susan M. , Ting Chien-Kun , Chu Ya-Chun , Loong Che-Chuan , Chan Kwok-Hon , Tsou Mei-Yung
Published: June 2012

Plasma-containing products are given during the pre-anhepatic stage of liver transplant surgery to correct abnormal thromboelastogram (TEG) values and prevent blood loss due to coagulation defects. However, evidence suggests that abnormal TEG results do not always predict bleeding. We questioned what effect using higher TEG values to initiate treatment would have on blood loss. A single transfusion protocol was used for all patients who underwent liver transplantation between 2007 and 2010. Thirty-eight patients received coagulation products when standard TEG cutoff values were exceeded, whereas another 39 patients received coagulation products when the TEG values were 35% greater than normal. The results of postoperative coagulation tests for total blood loss and the use of blood products were compared for the 2 groups. When the critical TEG values for transfusion were higher, significantly fewer units of fresh frozen plasma (5.58 ± 6.49 versus 11.53 ± 6.66 U) and pheresis platelets (1.84 ± 1.33 versus 3.55 ± 1.43 U) were used. There were no differences in blood loss or postoperative blood product use. In conclusion, the use of higher critical TEG values to initiate the transfusion of plasma-containing products is not associated with increased blood loss. Further testing is necessary to identify what TEG value predicts bleeding due to a deficit in coagulation factors. Liver Transpl 18:1254–1258, 2012. © 2012 AASLD.
Feng Shui Principles in Residential Housing Selection
Authors: Wu Wann‐Yih , Yau Oliver H. M. , Lu Hsiao‐Yun
Published: June 2012

Feng Shui principles have a significant impact on consumers’ housing selection in Chinese societies. However, the importance of such beliefs in consumer's decision‐making processes has not been investigated in previous studies. Thus, an analytic hierarchy process was adopted to identify the importance of Feng Shui principles in the selection of residential properties. Furthermore, based on the theoretical foundations of the theory of reasoned action (TRA) and perceived risks, two empirical studies were conducted to verify how consumers use Feng Shui principles to influence their beliefs, attitudes, and purchasing decisions. The results indicate that consumers tend to place more emphasis on housing with good accessibility, no harmful objects, positive directional aspects, and harmony between Feng Shui and humans. The results further confirm that the TRA model is applicable when utilizing Feng Shui principles as stimuli to elicit consumer behaviors. Individuals who perceive higher risks related to violations of Feng Shui principles tend to more seriously consider the impact of such principles on their beliefs, attitudes, and purchasing behaviors with regard to residential properties. © 2012 Wiley Periodicals, Inc.
Dual Temperature and Thiol‐Responsive POEOMA‐Multisegmented Polydisulfides: Synthesis and Thermoresponsive Properties
Authors: Zhang Qian , Noh Seung Man , Nam Joon Hyun , Jung Hyun Wook , Park Jong Myung , Oh Jung Kwon
Published: June 2012

New thermoresponsive polydisulfides of POEOMA multiblocks linked with disulfide bonds having redox‐responsive properties are reported. These POEOMA‐multisegmented polydisulfides were synthesized by a new method employing a combined RAFT/aminolysis and reversible thiol‐disulfide redox reaction that centers on the synthesis of new disulfide‐labeled difunctional RAFT agent. RAFT polymerization proceeded in living fashion, yielding well‐defined POEOMA copolymers with middle disulfides and terminal RAFT species. They were then used as precursors for thiol‐disulfide polyexchange induced by aminolysis and reductive reaction followed by oxidation: these polydisulfides with different molecular weights and end groups ex hibited tunable thermoresponsive properties and thiol‐responsive degradation.
Expression of RNA‐binding proteins DND1 and FXR1 in the porcine ovary, and during oocyte maturation and early embryo development
Authors: Yang Cai‐Xia , Wright Elane C. , Ross Jason W.
Published: June 2012

The porcine oocyte and early embryo are transcriptionally quiescent following germinal vesicle breakdown in the oocyte and prior to activation of the embryonic genome, at approximately the 4‐cell stage of development. Despite a lack of new transcription, mRNA and protein repertoires are subject to regulation during this time. One potential mechanism of regulation is through the functional activity of miRNAs and/or the presence of specific RNA‐binding proteins. Both DND1 (dead end homolog 1) and FXR1 (fragile‐X‐mental retardation‐related protein 1) are RNA‐binding proteins that have been demonstrated to impact miRNA‐mediated, post‐transcriptional gene regulation. The objective was to characterize the presence and the expression changes in DND1 and FXR1 during pig oocyte maturation and early embryo development. DND1 and FXR1 expression were evaluated in oocytes and cumulus cells during meiotic progression and in 4‐cell stage embryos using quantitative RT‐PCR, Western blot analysis, and immunostaining. These data demonstrate DND1 and FXR1 mRNA are expressed in the maturing oocyte and early in vitro‐fertilized embryos, with significantly less DND1 in 4‐cell stage embryos as compared to germinal vesicle and metaphase II‐arrested oocytes. Based on immunohistochemistry, DND1 protein abundance is greater in secondary follicles in comparison to primary and tertiary follicles. Using ribonucleoprotein immunoprecipitation from germinal vesicle‐stage oocytes, DND1 was demonstrated to interact with several mRNAs associated with pluripotency. This work provides a better understanding of the biological relevance of DND1 and FXR1 during female gametogenesis and embryo development in pigs.Mol. Reprod. Dev. 79: 541‐552, 2012. © 2012 Wiley Periodicals, Inc.
Hybrid expression cassettes consisting of a milk protein promoter and a cytomegalovirus enhancer significantly increase mammary‐specific expression of human lactoferrin in transgenic mice
Authors: Cheng Yong , An Li‐you , Yuan Yu‐Guo , Wang Yi , Du Fu‐Liang , Yu Bao‐Li , Zhang Zheng‐Hong , Huang Yu‐Zheng , Yang Ting‐Jia
Published: June 2012

It is very important to develop an effective, specific, and robust expression cassette that ensures a high level of expression in the mammary glands. In this study, we designed and constructed a series of mammary gland‐specific vectors containing a complex hybrid promoter/enhancer by utilizing promoter sequences from milk proteins (i.e., goat β‐casein, bovine αs1‐casein, or goat β‐lactoglobulin) and cytomegalovirus enhancer sequences; vectors containing a single milk protein promoter served as controls. Chicken β‐globin insulator sequences were also included in some of these vectors. The expression of constructs was analyzed through the generation of transgenic mice. Enzyme‐linked immunosorbent assay (ELISA) analysis revealed that the hybrid promoter/enhancer could drive the expression of recombinant human lactoferrin (rhLF) cDNA at high levels (1.17–8.10 mg/ml) in the milk of transgenic mice, whereas control promoters achieved a very low rhLF expression (7–40 ng/ml). Moreover, the expression of rhLF was not detected in the serum or saliva of any transgenic animal. This result shows that all constructs, driven by the hybrid promoter/enhancer, had high mammary gland‐specific expression pattern. Together, our results suggest that the use of a hybrid promoter/enhancer is a valuable alternative approach for increasing mammary‐specific expression of recombinant hLF in a transgenic mouse model.Mol. Reprod. Dev. 79: 573‐585, 2012. © 2012 Wiley Periodicals, Inc.
Intramuscular adipose tissue and central activation in older adults
Authors: Yoshida Yuri , Marcus Robin L. , Lastayo Paul C.
Published: June 2012

Introduction: Intramuscular adipose tissue (IMAT) is a potential contributor to declining force production and may be related to impaired central activation; therefore, the purpose of this report is to describe IMAT composition and its association with central activation in older adults. The central activation ratio (CAR) of the knee extensors was assessed using a superimposition technique in 15 older adults (29 legs) along with the cross‐sectional area of IMAT and lean tissue. Results: IMAT and CAR are inversely related in older adults (r = −0.51, P = 0.005), and many subjects with high IMAT have deficits in central activation, whereas those with low IMAT have normal central activation. Conclusions: These novel findings may assist in unraveling why muscle force production and lean tissue cross‐sectional area are not strongly linked, as the ability to centrally activate muscle appears to be unrelated to lean muscle area and may be dependent in part on IMAT levels. Muscle Nerve 46:813–816, 2012
Combined Eulerian–PFEM approach for analysis of polymers in fire situations
Authors: Marti J. , Ryzhakov P. , Idelsohn S. , Oñate E.
Published: June 2012

In this paper, we present a computational algorithm for solving an important practical problem, namely, the thermoplastic polymer melting under fire conditions. We propose here a technique that aims at minimizing the computational cost. This is basically achieved by using the immersed boundary‐like approach, combining the particle finite element method for the polymer with an Eulerian formulation for the ambience. The polymer and ambience domains interact over the interface boundary. The boundary is explicitly defined by the position of the Lagrangian domain (polymer) within the background Eulerian mesh (ambience). This allows to solve the energy equation for both subdomains on the Eulerian mesh with different thermal properties. Radiative transport equation is exclusively considered for the ambience, and the heat exchange at the interface is modeled by calculating the radiant heat flux and imposing it as a natural boundary condition. Copyright © 2012 John Wiley & Sons, Ltd.
Effect of fiber weight fraction on mechanical properties of carbon–carbon composites
Authors: Naik Padmayya Shaniyara , Orangalu Surendranathan Attakuli , Londhe Neelakantha V.
Published: June 2012

This article presents the synthesis of carbon–carbon (C/C) composites by preformed yarn (PY) method, by varying the percentage of carbon fiber weight fraction. The PY used was carbon fiber bundle surrounded by coke and pitch which was enclosed in nylon‐6. Three types of samples with fiber weight fractions of 30, 40, and 50%, respectively, are fabricated and mechanical properties were studied. In each case, the PY was chopped and filled into a die of required shape and hot pressed at 500°C to get the preform composite. To obtain the carbonized and graphitic structure, the specimen was heat treated at 2500°C followed by soaking for 10 to 12 hrs. Further, two cycles pitch impregnation was done by hot isostatic pressing, to eliminate the voids and to increase the density hence to obtain good mechanical properties. The characteristics such as hardness, flexural strength, and impact strengths were studied. It is observed that, as the carbon fiber percentage increases, the properties also get improved, provided sintering is done at fairly higher temperatures such as 2700°C. The superiority of the new class of C/C composites made by the proposed PY technique over those obtained by the conventional methods is also demonstrated. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Tribological properties of ethylene–propylene–diene rubber + polypropylene + thermal‐shock‐resistant ceramic composites
Authors: Brostow Witold , Datashvili Tea , Geodakyan James
Published: June 2012

This work is part of a program on composites used in thermoelectric devices. Tribological properties of dynamic vulcanizate blends of polypropylene and ethylene‐propylene‐diene rubber filled with 5 wt% of microscale powder have been studied. The microscale thermal‐shock‐resistant ceramic filler contains α‐Al2O3, mullite (3Al2O3 · 2SiO2 or 2Al2O3SiO2), β‐spodumene glass‐ceramic and aluminium titanate. We found that our ceramic particles are abrasive; they cause strong abrasion of softer steel ball surfaces during dry sliding friction. To overcome the difficulty of particle dispersion and adhesion, the filler was modified through grafting using three types of organic molecules. Dry sliding friction was measured using four types of counter‐surfaces: tungsten carbide, Si3N2, 302 steel and 440 steel. Thermoplastic vulcanizate filled with neat ceramic powder shows the lowest friction compared to composites containing the same but surface‐treated powder. We introduce a ‘bump’ model to explain the tribological responses of our composites. ‘Naked’ or untreated ceramic particles protrude from the polymer surface and cause a decrease of the contact area compared to neat polymer. The ball partner surface has only a small contact area with the bumps. As contact surface area decreases, so does friction and the amount of heat generated during sliding friction testing. Chemical coupling of the ceramic to the matrix smoothens the bumps and increases the contact surface, giving a parallel increase in friction. Copyright © 2012 Society of Chemical Industry
Design of conduction band structure of TiO2 electrode using Nb doping for highly efficient dye‐sensitized solar cells
Authors: Tsvetkov Nikolay A. , Larina Liudmila L. , Shevaleevskiy Oleg , Al‐Ammar Essam A. , Ahn Byung Tae
Published: June 2012

A barrier layer of undoped TiO2 was deposited on the Nb‐doped TiO2 electrode to suppress the recombination at the Nb‐doped TiO2/dye–electrolyte interface for highly efficient dye‐sensitized solar cells (DSCs). The Nb content in TiO2 was varied in a range of 0.7–3.5 mol% to modify the TiO2 energy‐band structure. Nb‐doped TiO2/dye interfaces were characterized by a combination of ultraviolet photoemission spectroscopy and optical absorption spectroscopy measurements, allowing the determination of the conduction band minimum (CBM) of the TiO2 electrode and the lowest unoccupied molecular orbital of the N719 dye. The lowering of TiO2 CBM by Nb doping induced the increase in short‐circuit current of DSCs. However, open‐circuit voltage and fill factor are decreased, and this result was ascribed to the enhanced recombination at the Nb‐doped TiO2/dye–electrolyte interface. The effect of doping on charge transport in DSCs was analyzed using electrochemical impedance spectroscopy. We have shown that by introducing of TiO2 barrier layer, the Nb doping content, which results in DSC highest efficiency, can be increased because of the suppression of the dopant‐induced recombination. The energy conversion efficiency of the solar cells increased from 7.8% to 9.0% when undoped TiO2 electrode is replaced with electrode doped with 2.7 mol% of Nb because of the improvement of the electron injection and collection efficiencies. The correlation between the electronic structure of the TiO2 electrode, charge transfer characteristics, and photovoltaic parameters of DSCs is discussed. Copyright © 2012 John Wiley & Sons, Ltd.
Brane singularities with mixtures in the bulk
Authors: Antoniadis I. , Cotsakis S. , Klaoudatou I.
Published: June 2012

By extending previous analysis of the authors, a systematic study of the singularity structure and possible asymptotic behaviors of five‐dimensional braneworld solutions is performed in the case where the bulk is a mixture of an analog of perfect fluid (with a density and pressure depending on the extra coordinate) and a massless scalar field. The two bulk components interact by exchanging energy so that the total energy is conserved. In a particular range of the interaction parameters, we find flat brane general solutions avoiding the singularity at finite distance from the brane, in the same region of the equation of state constant parameter γ = P/ρ that we found previously in the absence of the bulk scalar field (‐1 < γ < ‐1/2).
Unified treatment of exactly solvable quantum potentials with confluent hypergeometric eigenfunctions: Generalized potentials
Authors: Peña J. J. , Morales J. , García‐Martínez J. , García‐Ravelo J.
Published: June 2012

In this work, we propose an alternative approach to transform a general second‐order differential equation (DE) into a Schrödinger‐like equation. As a useful application of the proposal, we consider explicitly the case of the confluent hypergeometric (CH) DE with the aim to unify all potentials having CH eigenfunctions. That is, the proposed approach allows us to obtain generalized potential models that contain as particular cases the standard exactly solvable potentials with CH solutions such as the one‐ and three‐dimensional Harmonic, Morse, Coulomb, and other well known potentials. Besides, due that the proposed method is general, it can be straightforwardly applied to other DE in the search of bound‐states solutions for new potential models that could be useful in quantum chemistry. © 2012 Wiley Periodicals, Inc.
Microsolvation effects on the stability of polyalanine in extended and polyproline II conformation
Authors: Ireta Joel
Published: June 2012

Microsolvation of a polyalanine chain in a fully extended structure (FES) and polyproline II conformation (PP‐II) is studied using density functional theory. Infinitely long systems are investigated to form infinite networks of hydrogen bonds (hbs) along the microsolvation shells. In this manner hbs cooperative effect is evaluated. The stability of microsolvated PP‐II respect to microsolvated FES is investigated by changing the number of adsorbed water molecules per residue (nw) from 2 to 11. It is found that PP‐II stability strongly depends on the nw value. For example, PP‐II is more stable respect to FES by ∼14 kcal/mol for nw = 9, however its stability drops to ∼4 kcal/mol for nw = 10. It is shown that such behavior is connected to cooperative effects at the hydration shell, where water‐water hbs strengthen up to 46%. Besides backbone‐water hbs weaken, most notably in FES where its strength is diminished by 36%. Such interplay between water‐water and backbone‐water hydrogen bonding leads to a marginal stability of PP‐II respect to FES for nw ≥ 10. © 2012 Wiley Periodicals, Inc.
Worldwide proficiency test for routine analysis of δ2H and δ18O in water by isotope‐ratio mass spectrometry and laser absorption spectroscopy
Authors: Wassenaar L. I. , Ahmad M. , Aggarwal P. , van Duren M. , Pöltenstein L. , Araguas L. , Kurttas T.
Published: June 2012

RATIONALE

The interpretation of stable hydrogen and oxygen isotope data in isotope hydrology relies on accurate, high‐precision analytical measurements of the 2H:1H and 18O:16O ratios in liquid H2O samples.

METHODS

A synthesis of the International Atomic Energy Agency (IAEA) worldwide proficiency test for analytical laboratories conducting routine analysis of δ2H and δ18O values in water (WICO2011) by isotope‐ratio mass spectrometry (IRMS) and laser absorption spectroscopy (LAS) technology has been carried out.

RESULTS

This test revealed that >96% of the 160 laboratory submissions provided acceptable results within ±2‰ for δ2H values and ±0.2‰ for δ18O values of the established reference values for four test waters, and no difference in outcomes based on IRMS vs. LAS technology was found for good performing laboratories.

CONCLUSIONS

The leading cause of outliers appeared to be improper calibration or compromised storage of laboratory standard and primary reference waters; hence the importance of judicious storage of lab standards cannot be understated. The deprecated practice of single standard normalization was identified as a problem for some laboratories. We further recommend that laboratories strive to report parsimonious long‐term precisions based upon control standards, and to improve quantification and correction for LAS instrumental drift and inter‐sample carryover effects. Copyright © 2012 John Wiley & Sons, Ltd.
Gas‐phase behaviour of Ru(II) cyclopentadienyl‐derived complexes with N‐coordinated ligands by electrospray ionization mass spectrometry: fragmentation pathways and energetics
Authors: Madeira Paulo J. Amorim , Morais Tânia S. , Silva Tiago J. L. , Florindo Pedro , Garcia M. Helena
Published: June 2012

RATIONALE

The gas‐phase behaviour of six Ru(II) cyclopentadienyl‐derived complexes with N‐coordinated ligands, compounds with antitumor activities against several cancer lines, was studied. This was performed with the intent of establishing fragmentation pathways and to determine the Ru–LN and Ru–LP ligand bond dissociation energies. Such knowledge can be an important tool for the postulation of the mechanisms of action of these anticancer drugs.

METHODS

Two types of instruments equipped with electrospray ionisation were used (ion trap and a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer). The dissociation energies were determined using energy‐variable collision‐induced dissociation measurements in the ion trap. The FTICR instrument was used to perform MSn experiments on one of the compounds and to obtain accurate mass measurements. Theoretical calculations were performed at the density functional theory (DFT) level using two different functionals (B3LYP and M06L) to estimate the dissociation energies of the complexes under study.

RESULTS

The influence of the LN on the bond dissociation energy (D) of RuCp compounds with different nitrogen ligands was studied. The lability order of LN was: imidazole < 1‐butylimidazole < 5‐phenyl‐1H‐tetrazole < 1‐benzylimidazole. Both the functionals used gave the following ligand lability order: imidazole < 1‐benzylimidazole < 5‐phenyl‐1H‐tetrazole < 1‐butylimidazole. It is clear that there is an inversion between 1‐benzylimidazole and 1‐butylimidazole for the experimental and theoretical lability orders. The M06L functional afforded values of D closer to the experimental values. The type of phosphane (LP) influenced the dissociation energies, with values of D being higher for Ru–LN with 1‐butylimidazole when the phosphane was 1,2‐bis(diphenylphosphino)ethane. The Ru–LP bond dissociation energy for triphenylphosphane was independent of the type of complex.

CONCLUSIONS

The D values of Ru–LN and Ru–LP were determined for all six compounds and compared with the values calculated by the DFT method. For the imidazole‐derived ligands the energy trend was rationalized in terms of the increasing extension of the σ‐donation/π‐backdonation effect. The bond dissociation energy of Ru–PPh3 was independent of the fragmentations. Copyright © 2012 John Wiley & Sons, Ltd.
Atmospheric pressure photoionization mass spectrometry as a valuable method for the identification of polyisoprenoid alcohols
Authors: Kania Magdalena , Skorupinska‐Tudek Karolina , Swiezewska Ewa , Danikiewicz Witold
Published: June 2012

RATIONALE

The aim of this study was to determine whether Atmospheric Pressure Photoionization (APPI) was better suited for the mass spectrometric (MS) analysis of polyisoprenoid alcohols than the commonly used Electrospray Ionization (ESI) method. The APPI method should make possible the use of non‐polar solvents without any of the additives required by ESI, together with improved detection limits.

METHODS

The liquid chromatography (LC)/APPI‐MS and LC/ESI‐MS spectra of polyisoprenoid alcohol standards were acquired in both positive and negative ion mode, in methanol and hexane, using a triple quadrupole/linear ion trap tandem mass spectrometer equipped with both an ESI and an APPI ion source.

RESULTS

In the positive ion mode peaks corresponding to [M + H − H2O]+ and [M + H]+ ions were observed in the APPI‐MS spectra of polyprenols and dolichols, respectively. In the negative ion mode peaks corresponding to [M + O2]−• and [M + Cl]− ions were observed for both classes of polyisoprenoid alcohols. The detection limit of polyisoprenoid alcohols was established at the level of 10 pg.

CONCLUSIONS

APPI turned out to be a method of choice for the identification and quantitation of polyisoprenoid alcohols by MS using both polar and non‐polar solvents. APPI also enabled greater differentiation of polyprenols and dolichols occurring together in natural samples and gave much better TIC chromatograms without the need for the post‐column salt addition required by ESI. Copyright © 2012 John Wiley & Sons, Ltd.
Donor Satellite Cell Engraftment Is SignificantlyAugmented When the Host Niche Is Preserved and Endogenous Satellite Cells Are Incapacitated
Authors: Boldrin Luisa , Neal Alice , Zammit Peter S. , Muntoni Francesco , Morgan Jennifer E.
Published: June 2012

Stem cell transplantation is already in clinical practice for certain genetic diseases and is a promising therapy for dystrophic muscle. We used the mdx mouse model of Duchenne muscular dystrophy to investigate the effect of the host satellite cell niche on the contribution of donor muscle stem cells (satellite cells) to muscle regeneration. We found that incapacitation of the host satellite cells and preservation of the muscle niche promote donor satellite cell contribution to muscle regeneration and functional reconstitution of the satellite cell compartment. But, if the host niche is not promptly refilled, or is filled by competent host satellite cells, it becomes nonfunctional and donor engraftment is negligible. Application of this regimen to aged host muscles also promotes efficient regeneration from aged donor satellite cells. In contrast, if the niche is destroyed, yet host satellite cells remain proliferation-competent, donor-derived engraftment is trivial. Thus preservation of the satellite cell niche, concomitant with functional impairment of the majority of satellite cells within dystrophic human muscles, may improve the efficiency of stem cell therapy.
A semiquinone glucoside derivative provides protection to male reproductive system of the mice against gamma radiation toxicity
Authors: Patel Dev Dutt , Bansal Deen Dayal , Mishra Saurabh , Arora Rajesh , Sharma Rakesh Kumar , Jain Swatantra Kumar , Kumar Raj
Published: June 2012

Present investigation was carried out to evaluate the radioprotective efficacy of a novel Semiquinone glucoside derivative (SQGD), isolated from Bacillus sp. INM‐1, in the male reproductive system of BALB/c mice. Animals were administered 50 mg/kg b.wt. (i.p.) SQGD 2 h before whole body γ‐irradiation (10 Gy). Radiation‐induced cellular toxicity and its modulation by SQGD pretreatment was evaluated in the mice testes by quantitative histological and protein expression analysis. SQGD pretreatment protects irradiated mice from radiation‐induced testicular atrophy and germ cells degeneration, which may lead to emptiness of seminiferous tubules. Significant decrease in P53 and P21(Cip/WAF‐1) expression was observed in the irradiated mice pretreated (2 h) by SQGD at 6 h compared with only irradiated mice. However, contrary to P53, expressions of P21 at latter time, that is, 24–72 h was found to be increased significantly in the irradiated mice pretreated by SQGD. Significant increase in the intact PARP‐1 protein expression were observed in the testes of the mice pretreated by SQGD 2 h before irradiation at 24–72 h compared with the only irradiated mice, whereas significant increase in PARP‐1 cleaved fragment was noticed at 24 h. Similarly, significant increase in NF‐kB and BCL‐2/BAX expressions ratio was noticed in SQGD‐treated mice (± irradiation) compared with irradiated mice, suggested a role of SQGD in the activation of prosurvival signaling in the testicular germinal cells population of the irradiated mice and thus contributed to protection against lethal γ‐irradiation. © 2012 Wiley Periodicals, Inc. Environ Toxicol 29: 558–567, 2014.
Micronuclei, nucleoplasmic bridges, and nuclear buds induced in human lymphocytes by the fungicide signum and its active ingredients (boscalid and pyraclostrobin)
Authors: Çayır Akin , Coskun Munevver , Coskun Mahmut
Published: June 2012

The aim of this study was to investigate the genotoxic and cytotoxic potential of the Signum fungicide and its active ingredients (boscalid and pyraclostrobin) on human peripheral blood lymphocytes using the cytokinesis‐block micronucleus (CBMN) assay. Micronuclei (MNi), nucleoplasmic bridges (NPBs), nuclear bud (NBUDs) formations, and the cytokinesis‐block proliferation index (CBPI) were evaluated in treated lymphocytes in Go (cells were treated and then kept in culture without stimulation for 24 h) and proliferation phases (cells were treated after 44 h culture in medium containing phytohemagglutinin). MN formation in lymphocytes treated in G0 statistically increased at doses of 2, 6, and 25 μg/mL signum; 0.5 and 2 μg/mL boscalid; and 0.5, 1.5, and 2 μg/mL pyraclostrobin; while NPB formation increased at a dose of 0.25 μg/mL pyraclostrobin. All concentrations of each fungicide did not statistically increase NBUD formation, while the cytotoxicity increased the dependent on concentration in lymphocytes treated in G0. Doses of 0.5, 1, 1.5, and 3 μg/mL signum; 0.5, 1, and 1.5 μg/mL boscalid; and 0.75 μg/mL pyraclostrobin statistically increased the MN formation in proliferating lymphocytes. NPB formation increased in proliferating lymphocytes at doses of 1, 1.5, 2, and 3 μg/mL signum and at a dose of 0.75 μg/mL pyraclostrobin. In addition, a dose of 0.75 μg/mL pyraclostrobin increased NBUD frequencies. Cytotoxicity increased with increasing concentrations of each fungicide. It is concluded that signum, boscalid, and pyraclostrobin may be genotoxic and cytotoxic in vitro human peripheral blood lymphocytes in consideration of each of the two protocols. © 2012 Wiley Periodicals, Inc. Environ Toxicol 29: 723–732, 2014.
Subspace clustering
Authors: Kriegel Hans‐Peter , Kröger Peer , Zimek Arthur
Published: June 2012

Subspace clusteringrefers to the task of identifying clusters of similar objects or data records (vectors) where the similarity is defined with respect to a subset of the attributes (i.e., a subspace of the data space). The subspace is not necessarily (and actually is usually not) the same for different clusters within one clustering solution. In this article, the problems motivating subspace clustering are sketched, different definitions and usages of subspaces for clustering are described, and exemplary algorithmic solutions are discussed. Finally, we sketch current research directions. © 2012 Wiley Periodicals, Inc.

This article is categorized under:

Technologies > Structure Discovery and Clustering
Clustering high dimensional data
Authors: Assent Ira
Published: June 2012

High‐dimensional data, i.e., data described by a large number of attributes, pose specific challenges to clustering. The so‐called ‘curse of dimensionality’, coined originally to describe the general increase in complexity of various computational problems as dimensionality increases, is known to render traditional clustering algorithms ineffective. The curse of dimensionality, among other effects, means that with increasing number of dimensions, a loss of meaningful differentiation between similar and dissimilar objects is observed. As high‐dimensional objects appear almost alike, new approaches for clustering are required. Consequently, recent research has focused on developing techniques and clustering algorithms specifically for high‐dimensional data. Still, open research issues remain. Clustering is a data mining task devoted to the automatic grouping of data based on mutual similarity. Each cluster groups objects that are similar to one another, whereas dissimilar objects are assigned to different clusters, possibly separating out noise. In this manner, clusters describe the data structure in an unsupervised manner, i.e., without the need for class labels. A number of clustering paradigms exist that provide different cluster models and different algorithmic approaches for cluster detection. Common to all approaches is the fact that they require some underlying assessment of similarity between data objects. In this article, we provide an overview of the effects of high‐dimensional spaces, and their implications for different clustering paradigms. We review models and algorithms that address clustering in high dimensions, with pointers to the literature, and sketch open research issues. We conclude with a summary of the state of the art. © 2012 Wiley Periodicals, Inc.

This article is categorized under:

Technologies > Structure Discovery and Clustering
Optimization of ordered plasmid assembly by gap repair in Saccharomyces cerevisiae
Authors: Eckert‐Boulet Nadine , Pedersen Mette Louise , Krogh Berit Olsen , Lisby Michael
Published: June 2012

Combinatorial genetic libraries are powerful tools for diversifying and optimizing biomolecules. The process of library assembly is a major limiting factor for library complexity and quality. Gap repair by homologous recombination in Saccharomyces cerevisiae can facilitate in vivo assembly of DNA fragments sharing short patches of sequence homology, thereby supporting generation of high‐complexity libraries without compromising fidelity. In this study, we have optimized the ordered assembly of three DNA fragments into a gapped vector by in vivo homologous recombination. Assembly is achieved by co‐transformation of the DNA fragments and the gapped vector, using a modified lithium acetate protocol. The optimal gap‐repair efficiency is found at a 1:80 molar ratio of gapped vector to each of the three fragments. We measured gap‐repair efficiency in different genetic backgrounds and observed increased efficiency in mutants carrying a deletion of the SGS1 helicase‐encoding gene. Using our experimental conditions, a gap‐repair efficiency of > 106 plasmid‐harbouring colonies/µg gapped vector DNA is obtained in a single transformation, with a recombination fidelity > 90%. Copyright © 2012 John Wiley & Sons, Ltd.
Inductive study of confidentiality: for everyone
Authors: Bella Giampaolo
Published: June 2012

The Inductive Method is among the most established tools to analyse security protocols formally. It has successfully coped with large, deployed protocols, and its findings are widely published. However, perhaps due to its embedding in a theorem prover or to the lack of tutorial publications, it is at times criticised to require super-specialised skills and hence to be rather impractical. This paper aims at showing that criticism to be stereotypical. It pursues its aim by presenting the first tutorial-style paper to using the Inductive Method. This paper cannot cover every aspect of the method. It focuses on a key one, that is how the Inductive Method treats one of the main goals of security protocols: confidentiality against a threat model. The treatment of that goal, which may seem elegant in the Inductive Method, in fact forms a key aspect of all protocol analysis tools, hence the paper motivation rises still. With only standard skills as a requirement, the reader is guided step by step towards design and proof of significant confidentiality theorems. These are developed against two threat models, the standard Dolev–Yao and a more up-to-date one, the General Attacker, the latter turning out particularly useful also for didactic purposes.
Isolation of a Δ5 Desaturase Gene from Euglena gracilis and Functional Dissection of Its HPGG and HDASH Motifs
Authors: Pollak Dana Walters , Bostick Michael W. , Yoon Hyeryoung , Wang Jamie , Hollerbach Dieter H. , He Hongxian , Damude Howard G. , Zhang Hongxiang , Yadav Narendra S. , Hong Seung‐Pyo , Sharpe Pamela , Xue Zhixiong , Zhu Quinn
Published: June 2012

Delta (Δ) 5 desaturase is a key enzyme for the biosynthesis of health‐beneficial long chain polyunsaturated fatty acids such as arachidonic acid (ARA, C20:4n‐6), eicosapentaenoic acid (C20:5n‐3) and docosahexaenoic acid (C22:6n‐3) via the “desaturation and elongation” pathways. A full length Δ5 desaturase gene from Euglena gracilis (EgΔ5D) was isolated by cloning the products of polymerase chain reaction with degenerate oligonucleotides as primers, followed by 5′ and 3′ rapid amplification of cDNA ends. The whole coding region of EgΔ5D was 1,350 nucleotides in length and encoded a polypeptide of 449 amino acids. BlastP search showed that EgΔ5D has about 39 % identity with a Δ5 desaturase of Phaeodactylum tricornutum. In a genetically modified dihomo‐gamma‐linoleic acid (DGLA, C20:3n‐6) producing Yarrowia lipolytica strain, EgΔ5D had strong Δ5 desaturase activity with DGLA to ARA conversion of more than 24 %. Functional dissection of its HPGG and HDASH motifs demonstrated that both motifs were important, but not necessary in the exact form as encoded for the enzyme activity of EgΔ5D. A double mutant EgΔ5D‐34G158G with altered sequences within both HPGG and HDASH motifs was generated and exhibited Δ5 desaturase activity similar to the wild type EgΔ5D. Codon optimization of the N‐terminal region of EgΔ5D‐34G158G and substitution of the arginine with serine at residue 347 improved substrate conversion to 27.6 %.
A coherence analysis module for SciPo: providing suggestions for scientific abstracts written in Portuguese
Authors: de Souza Vinícius Mourão Alves , Feltrim Valéria Delisandra
Published: June 2012

SciPo is a writing tool whose ultimate goal is to assist novice writers in producing scientific writing in Portuguese, focusing primarily on abstracts and introductions from computer science. In this paper, we describe the development of a coherence analysis module for SciPo, which aims to automatically detect semantic coherence aspects of abstracts and provide suggestions for improvement. At the core of this new module are classifiers that identify different semantic relationships among sentences within an abstract and hence indicate semantic aspects that add coherence to the abstract. Such classifiers are based on a set of features extracted automatically from the surface of the text and by Latent Semantic Analysis processing. All classifiers were evaluated intrinsically and their performance was higher than the baseline. We also resorted to actual users to evaluate our coherence analysis module, which has been incorporated into the SciPo system, and results demonstrate its potential to help users write scientific abstracts with a higher level of coherence.