bluuebunny/crossref_metadata_2025 huggingface dataset:
Second‐order accurate derivatives and integration schemes for meshfree methods
Authors: Duan Qinglin , Li Xikui , Zhang Hongwu , Belytschko Ted
Published: June 2012

The consistency condition for the nodal derivatives in traditional meshfree Galerkin methods is only the differentiation of the approximation consistency (DAC). One missing part is the consistency between a nodal shape function and its derivatives in terms of the divergence theorem in numerical forms. In this paper, a consistency framework for the meshfree nodal derivatives including the DAC and the discrete divergence consistency (DDC) is proposed. The summation of the linear DDC over the whole computational domain leads to the so‐called integration constraint in the literature. A three‐point integration scheme using background triangle elements is developed, in which the corrected derivatives are computed by the satisfaction of the quadratic DDC. We prove that such smoothed derivatives also meet the quadratic DAC, and therefore, the proposed scheme possesses the quadratic consistency that leads to its name QC3. Numerical results show that QC3 is the only method that can pass both the linear and the quadratic patch tests and achieves the best performances for all the four examples in terms of stability, convergence, accuracy, and efficiency among all the tested methods. Particularly, it shows a huge improvement for the existing linearly consistent one‐point integration method in some examples. Copyright © 2012 John Wiley & Sons, Ltd.
Who Benefits from KIPP?
Authors: Angrist Joshua D. , Dynarski Susan M. , Kane Thomas J. , Pathak Parag A. , Walters Christopher R.
Published: June 2012

The nation's largest charter management organization is the Knowledge is Power Program (KIPP). KIPP schools are emblematic of the No Excuses approach to public education, a highly standardized and widely replicated charter model that features a long school day, an extended school year, selective teacher hiring, strict behavior norms, and emphasizes traditional reading and math skills. No Excuses charter schools are sometimes said to target relatively motivated high achievers at the expense of students who are more difficult to teach, including limited English proficiency (LEP) and special education (SPED) students, as well as students with low baseline achievement levels. We use applicant lotteries to evaluate the impact of KIPP Academy Lynn, a KIPP school in Lynn, Massachusetts that typifies the KIPP approach. Our analysis focuses on special needs students that may be underserved. The results show average achievement gains of 0.36 standard deviations in math and 0.12 standard deviations in reading for each year spent at KIPP Lynn, with the largest gains coming from the LEP, SPED, and low‐achievement groups. Average reading gains are driven almost entirely by SPED and LEP students, whose reading scores rise by roughly 0.35 standard deviations for each year spent at KIPP Lynn.
Goserelin and bicalutamide treatments alter the expression of microRNAs in the prostate
Authors: Lehmusvaara Saara , Erkkilä Timo , Urbanucci Alfonso , Jalava Sanni , Seppälä Janne , Kaipia Antti , Kujala Paula , Lähdesmäki Harri , Tammela Teuvo L.J. , Visakorpi Tapio
Published: June 2012

BACKGROUND

Although endocrine therapy has been used for decades, its influence on the expression of microRNAs (miRNAs) in clinical tissue specimens has not been analyzed. Moreover, the effects of the TMPRSS2:ERG fusion on the expression of miRNAs in hormone naïve and endocrine‐treated prostate cancers are poorly understood.

METHODS

We used clinical material from a neoadjuvant trial consisting of 28 men treated with goserelin (n = 8), bicalutamide (n = 9), or no treatment (n = 11) for 3 months prior to radical prostatectomy. Freshly frozen specimens were used for microarray analysis of 723 human miRNAs. Specific miRNA expression in cancer, benign epithelium and stromal tissue compartments was predicted with an in silico Bayesian modeling tool.

RESULTS

The expression of 52, 44, and 34 miRNAs was affected >1.4‐fold by the endocrine treatment in the cancer, non‐malignant epithelium, and stromal compartments, respectively. Of the 52 miRNAs, only 10 were equally affected by the two treatment modalities in the cancer compartment. Twenty‐six of the 52 genes (50%) showed AR binding sites in their proximity in either VCaP or LNCaP cell lines. Forty‐seven miRNAs were differentially expressed in TMPRSS2:ERG fusion positive compared with fusion negative cases. Endocrine treatment reduced the differences between fusion positive and negative cases.

CONCLUSIONS

Goserelin treatment and bicalutamide treatment mostly affected the expression of different miRNAs. The effect clearly varied in different tissue compartments. TMPRSS2:ERG fusion positive and negative cases showed differential expression of miRNAs, and the difference was diminished by androgen ablation. Prostate 73: 101–112, 2013. © 2012 Wiley Periodicals, Inc.
Ardisianone, a natural benzoquinone, efficiently induces apoptosis in human hormone‐refractory prostate cancers through mitochondrial damage stress and survivin downregulation
Authors: Yu Chia‐Chun , Wu Ping‐Jung , Hsu Jui‐Ling , Ho Yunn‐Fang , Hsu Lih‐Ching , Chang Yu‐Jia , Chang Hsun‐Shuo , Chen Ih‐Sheng , Guh Jih‐Hwa
Published: June 2012

BACKGROUND

Increasing evidence suggests that mitochondria play a central role in regulating cell apoptosis. Survivin, an inhibitor of apoptosis protein (IAP) family member, mediates resistance to cancer chemotherapy particularly in prostate cancers. Therefore, development of anticancer agents targeting mitochondria and survivin is a potential strategy.

METHOD

Cell proliferation was examined by sulforhodamine B, CFSE staining, and clonogenic assays. Mitochondrial membrane potential (ΔΨm) and reactive oxygen species (ROS) were detected by flow cytometric analysis. Protein expression was detected by Western blot. RNA levels were examined by reverse transcription polymerase chain reaction assay. Overexpression of constitutively active Akt was also used in this study.

RESULTS

Ardisianone, a natural benzoquinone derivative, displayed anti‐proliferative and apoptotic activities against human hormone‐refractory prostate cancer cells (HRPC), PC‐3, and DU‐145. Ardisianone dramatically induced mitochondrial damage, identified by downregulation of Bcl‐2 family proteins, ROS production, and loss of ΔΨm. Ardisianone also inhibited Akt and mTOR/p70S6K pathways and induced a fast downregulation of survivin, leading to activation of mitochondria‐involved caspase cascades. Overexpression of constitutively active Akt partly rescued ardisianone‐mediated apoptotic signaling cascades. Furthermore, a long‐term treatment of ardisianone caused an increase of endoplasmic reticulum (ER) stress, upregulation of cIAP1 and cIAP2, and apoptosis‐inducing factor (AIF)‐mediated caspase‐independent apoptosis.

CONCLUSIONS

The data suggest that the ardisianone induces apoptosis in human prostate cancers through mitochondrial damage stress, leading to the inhibition of mTOR/p70S6K pathway, downregulation of Bcl‐2 family members, degradation of survivin, and activation of caspase cascades. The data provide evidence supporting that ardisianone is a potential anticancer agent against HRPCs. Prostate 73: 133–145, 2013. © 2012 Wiley Periodicals, Inc.
Through the looking glass – a new world of proteins enabled by chemical synthesis
Authors: Kent Stephen , Sohma Youhei , Liu Suhuai , Bang Duhee , Pentelute Brad , Mandal Kalyaneswar
Published: June 2012

‘Chemical ligation’ – the regioselective and chemoselective covalent condensation of unprotected peptide segments – has enabled the synthesis of polypeptide chains of more than 200 amino acids. An efficient total chemical synthesis of the insulin molecule has been devised on the basis of a key ester‐linked intermediate that is chemically converted to fully active human insulin. Enzyme molecules of defined covalent structure and with full enzymatic activity have been prepared and characterized by high‐resolution X‐ray crystallography. A ‘glycoprotein mimetic’ of defined chemical structure and with a mass of 50,825 Da, has been prepared and shown to have full biological activity and improved pharmacokinetic properties. d‐Protein molecules that are the mirror images of proteins found in the natural world have been prepared by total chemical synthesis. Racemic protein mixtures, consisting of the d‐enantiomers and l‐enantiomers of a protein molecule, form highly ordered centrosymmetric crystals with great ease; this has enabled the determination of the crystal structures of recalcitrant protein molecules. A protein with a novel linear‐loop covalent topology of the peptide chain has been designed and synthesized and its structure determined by facile crystallization as the quasi‐racemate with the d‐form of the native protein molecule. We have developed an optimized total chemical synthesis of biologically active vascular endothelial growth factor‐A; total synthesis of the mirror‐image protein will be used to systematically develop d‐protein antagonists of this important growth factor. The total chemical synthesis of proteins is now a practical reality and enables access to a new world of protein molecules. Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.
Structure and electrical properties in the K1/2Bi1/2TiO3–K1/2Bi1/2ZrO3 solid solution (KBT–KBZ)
Authors: Bengagi M. , Morini F. , El Maaoui M. , Marchet P.
Published: June 2012

The present work is devoted to the study of the Zr4+/Ti4 substitution in the K1/2Bi1/2Ti(1–x)ZrxO3 solid solution (x = 0.0 to x = 1.0), based upon the K1/2Bi1/2TiO3 (KBT) ferroelectric compound. The tetragonal distortion of KBT is suppressed by this substitution and leads to the cubic compound K1/2Bi1/2ZrO3 (KBZ). These results agree with the values of the ionic radii of the Zr4+ and Ti4 ions ($r_{{\rm Ti}^{4 + } } $ = 0.605 Å and $r_{{\rm Zr}^{4 + } } $ = 0.72 Å). Close to KBT (x ≤ 0.05), the symmetry remains tetragonal. For higher values of x, the “a” lattice parameter (cubic indexing) follows Vegard's law, thus confirming the formation of a solid solution. The transformation from tetragonal to cubic proceeds via an intermediate pseudocubic symmetry (0.1 ≤ x < 0.5), for which the X‐ray diffraction peaks present small broadening and asymmetry. For x ≥ 0.5 and up to the KBZ compound (a ≈ 4.158 Å), the samples are cubic but some extra peaks are also observed, indicating the occurrence of a secondary phase. The microstructure shows fine‐grained ceramic samples for the first range, while for the KBZ‐rich range the grains are micrometer‐sized and associated to very small grains of the secondary phase. Piezoelectricity is observed for the tetragonal and pseudocubic range, the substitution quickly reducing the piezoelectric properties. The measurement of the dielectric properties revealed close to KBT a dielectric anomaly probably associated to the tetragonal–cubic phase transition. For the pseudocubic and cubic range, a broad dielectric anomaly is observed around 300 °C, corresponding to a relaxor behavior.

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Transmission performance of a low‐loss metal–insulator–semiconductor plasmonic phase‐shift Bragg grating
Authors: Xiao Jing , Liu Jiansheng , Zheng Zheng , Bian Yusheng , Wang Guanjun , Li Shuna
Published: June 2012

We propose a plasmonics phase‐shift Bragg grating based on a metal–insulator–semiconductor structure in the wavelength range of 1400–1700 nm. The Bragg grating is formed by a periodic height variation of a semiconductor strip that is separated from a metal surface by a nanoscale insulator layer. Moreover, a phase‐shift structure was introduced in the middle of the Bragg grating. Simulation results demonstrate that the proposed structure exhibits good filtering characteristics with a strong field enhancement. The proposed phase‐shift Bragg grating could be used as an ultracompact filter and enable on‐chip integration of photonic circuits.
Resistive‐switching behavior and mechanism in copper‐nitride thin films prepared by DC magnetron sputtering
Authors: Zhu Wei , Zhang Xin , Fu Xiaoniu , Zhou Yongning , Luo Shengyun , Wu Xiaojing
Published: June 2012

Resistive random access memory (RRAM) devices are made by copper nitride films prepared by DC magnetron sputtering. After a forming process, the CuxN‐based RRAM devices show bipolar character with low operation voltage and distinguishable resistance ratio. The fitting results for the electrical measurements and the conducting atomic force microscope (CAFM) analysis indicate that resistive switching mechanism is consistent with the formation and rupture of conducting filaments. Simultaneously, the distribution of conducting filaments measured by CAFM reveals a promising potential to fabricate high‐density RRAM device by using this material. The mechanism of the formation of conducting filaments is discussed based on our results.
Efficient second harmonic generation by birefringent phase matching in femtosecond‐laser‐inscribed KTP cladding waveguides
Authors: Dong Ningning , Chen Feng , Vázquez de Aldana J. R.
Published: June 2012

We report on the fabrication of nonlinear KTiOPO4 (KTP) cladding waveguides by using femtosecond‐laser direct inscription. The produced guiding structures with a circular cross section of ∼100 μm diameter support good light confinement both for the visible and infrared, for TE and TM polarization. Under the 1064 nm pulsed fundamental pump beam, guided‐wave second harmonic generation (SHG) at 532 nm has been realized with an optical conversion efficiency as high as 45.6% (∼0.076% W–1 cm–2), which is three times the magnitude of the normalized efficiency obtained for “double‐line” KTP waveguides (fabricated with the aim of comparison), thus showing an intriguing potential as integrated frequency converters. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Molecular dynamics simulation for infrared spectroscopy with intramolecular forces from electronic properties of on‐the‐fly quantum chemical calculations
Authors: Ueno Seiji , Tanimura Yoshitaka , Ten‐no Seiichiro
Published: June 2012

We calculated vibrational spectra by means of a molecular dynamics simulation which utilizes intramolecular forces from ab initio molecular orbital calculations for instantaneous configurations of each molecule. Intermolecular interactions were determined with conventional force fields. Calculated molecular orbitals from the time‐dependent, instantaneous molecular configurations were also used to evaluate dipole moment and partial charges. We examined the validity of the present approach by evaluating infrared spectra for liquid carbon dioxide and water. We could capture some important features of intramolecular vibrational spectra of molecular liquids by this method, albeit there is room for further improvement in the descriptions of intermolecular interactions, especially of hydrogen bond. Possible extensions for accurate intermolecular and intramolecular vibrational spectrum were discussed. © 2012 Wiley Periodicals, Inc.
Exploring new species on the [H, S, Se, Cl] potential energy surface
Authors: Hermoso Willian , Jaufeerally Naziah B. , Ramasami Ponnadurai , Ornellas Fernando R.
Published: June 2012

This investigation is concerned with the characterization of seleno‐sulfide‐halogen model systems, the isomerization processes, and the dissociation into diatomic fragment channels on the [H, S, Se, Cl] potential energy surface. Structural, energetic, and vibrational data were obtained at the CCSD(T) and MP2 levels of theory with the series of correlation consistent basis sets and extrapolated to the complete basis set (CBS) limit. For the frequencies, additional computations were performed to include the contribution of anharmonic effects, and for the determination of the heats of formation, important corrections incorporating core‐valence correlation effects and relativistic effects (scalar and spin‐orbit) were taken into account. CCSD(T)/CBS relative stability (kcal mol−1) follows the order: HSSeCl (0.0), HSeSCl (8.80), SSeHCl (23.52), and SeSHCl (25.87). The cis‐rotational barrier for the two lowest isomers is practically identical (10.14 and 10.09 kcal mol−1), whereas for the trans barrier, we obtained 9.25 (HSSeCl) and 8.45 (HSeSCl) kcal mol−1. Dissociation of HSSeCl (HSeSCl) into HS (HSe) + SeCl (SCl) requires 59.70 (56.30) kcal mol−1. For the most stable isomer, we predict a value of the heat of formation at 298.15 K of 2.53 kcal mol−1. One of the outcomes of this research is that the MP2 results are consistent with those of CCSD(T). The MP2 method turns out to be a reliable alternative for a first exploration of larger catenated species, although it accounts for a lesser fraction of correlation effects. © 2012 Wiley Periodicals, Inc.
Structure and energetics of cyclopropane carboxaldehyde
Authors: Trindle Carl , Bleda Erdi A. , Altun Zikri
Published: June 2012

We use the energies obtained by a focal point analysis including extrapolation from results with basis sets cc‐pVnZ and aug‐cc‐pVnZ with n up to 4 and correlation corrections through CCSD(T), to estimate thermodynamic functions for the syn and anti isomers of cyclopropane carboxaldehyde (CPCA). These agree with values obtained by well‐established thermochemical schemes CBS‐QB3 and G4. The structures obtained in these studies also conform to the best experimental determination of the rotational constants in the gas phase. The kinetics of gas phase interconversion of the syn‐ and anti‐isomers of CPCA have been studied by a chirped‐pulse dynamic rotational spectroscopy. Computational modeling of the internal rotational potential allows the estimate of the interconversion rates by statistical (RRKM) methods. RRKM rates using a range of barrier heights including a CBS‐Q estimate are more than 10× the rates deduced from the dynamical rotational spectra. This suggests that nonstatistical effects may be limiting the rate. Detailed study of the interconversion potential by a variant of the focal point analysis suggests that previous estimates of the barrier may be too low, and thus, the inferred rice‐ramsperger‐kassel‐marcus (RRKM) rate could be too high. These results cast some doubt on the presence of nonstatistical effects and suggest that molecular dynamics studies should be conducted to characterize the energy flow in detail. © 2013 Wiley Periodicals, Inc.
Pseudo jahn‐teller origin of bending distortions in renner‐teller molecules and its spectroscopic implications
Authors: Garcia‐Fernandez Pablo , Bersuker Isaac B.
Published: June 2012

In an important reverse of understanding we show that the Renner‐Teller effect (RTE) which has been considered as the driving force of bending instability of linear molecules in degenerate states, is in fact producing just a splitting of the degenerate term and softening the ground state, but not bending instability; all instabilities and distortions of linear molecules are due to, and only to the mixing with appropriate excited states in the pseudo Jahn‐Teller effect (PJTE). The proof of this statement is given analytically in a general way, and it is supported by previously reported ab initio calculations showing that the contribution of the PJTE to the bending is overwhelmingly larger than the RTE softening. We show also that this finding, in addition to rationalizing the origin of instability of linear molecules, has significant implications in the interpretation of their properties, in particular, dipole moments, rotational level positions, spectroscopic selection rules, and line intensities. © 2012 Wiley Periodicals, Inc.
Molecular dynamics study of uncharged bupivacaine enantiomers in phospholipid bilayers
Authors: Martini M. Florencia , Pickholz Mónica
Published: June 2012

To investigate the effects of the uncharged bupivacaine (BVC) on the properties of model membranes of 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphatidylcholine (POPC), we have performed a series of molecular dynamics simulations. A very particular characteristic of the local anesthetic BVC, that is being discuss in the recent literature, is that their enantiomers R‐(+) (R‐BVC) and S‐(−) (S‐BVC) present different activities. In this way, we have studied both enantiomers in a POPC phospholipids bilayers at a high molar ratios [local anesthetic (LA):lipid of 1:3]. The simulations were able to capture important features of the BVC–phospholipid bilayer interactions: BVC molecules are found in the interior of the bilayer. The R‐BVC enantiomer follows a bimodal distribution with access to the water–lipid interface; while the S‐BVC is found, in more uniform distribution, at the hydrophobic region. A decrease in the acyl chain segment order parameters, SCD, compared to neat bilayers, is found. Furthermore, this behavior is more noticeable for the R‐BVC form. The found decrease in SCD is attributed to a larger accessible volume per lipid in the tail region. Our results could help to understand the higher toxicity of this enantiomer. © 2012 Wiley Periodicals, Inc.
Crystal structures and thermodynamic investigations of NaSc(BH4)4 from first‐principles calculations
Authors: Kim Ki Chul
Published: June 2012

The double cation borohydride NaSc(BH4)4 has a total H2 content of 12.67 wt.% and has been suggested as a potential candidate for hydrogen storage applications. This study reports first‐principles calculations of the structure and reaction thermodynamics of NaSc(BH4)4. The calculations indicate that NaSc(BH4)4 is decomposed into a mixture of ScB2, NaBH4, and Na2(B10H10) with H2 release of 9.3 wt.% at 118 K at a partial pressure of H2 of 100 bar. Reactant compositions that can destabilize NaSc(BH4)4 were evaluated. This effort identified four destabilization reactions that are predicted to have reaction thermodynamics for hydrogen release within the temperature range of 78–109 K. Even though the reactions conclusively produce undesired compounds, such as refractory materials or kinetically stable B12H12‐containing species, the thermodynamic study suggests a direction for improving the thermodynamics of double cation borohydride‐based systems being actively considered for hydrogen storage applications. © 2012 Wiley Periodicals, Inc.
Primary ion implantation and recoil implantation effects in Cs depth profiling of thin metallic layers on LiNbO3
Authors: Ciampolillo M. V. , Sada C.
Published: June 2012

Depth profiles obtained under Cs bombardment of samples of crystalline lithium niobate (LiNbO3) covered with a thin layer of metal display some artifacts related to metal/LiNbO3 interface effects. The altered yields of Li and Nb secondary ions in the first 50 nm after erosion of the metal layer can be interpreted in terms of different stopping powers between metal and LiNbO3. In this study, two typical samples are investigated and the artifacts are qualitatively explained by comparing experimental profiles and simulations performed with the transport of ions in matter code. The similarity between experiment and simulation suggests that the ballistic interpretation of the artifacts is appropriate. Copyright © 2012 John Wiley & Sons, Ltd.
Time‐of‐flight secondary ion mass spectroscopic characterization of the nitrogen profile of shallow gate oxynitride thermally grown on a silicon substrate
Authors: Zhu Lei , Teo H. W. , Ong Kenny , Huang Y. H. , Hua Y. N.
Published: June 2012

Silicon oxynitride has been used as a shallow gate oxide material for microelectronics and its thickness has been reduced over the years to only a few tens of angstroms due to device size scaling. The nitride distribution and density characteristic in the gate oxide thus becomes imperative for the devices. The shallow depth profiling capability using time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) has huge potential for the nitrogen characterization of the shallow gate oxide film. In this article, both positive and negative spectra of TOF‐SIMS on silicon oxynitride have been extensively studied and it was found that the silicon nitride clusters SixN− (x = 1–4) are able to represent the nitrogen profiles because their ion yields are high enough, especially for the low‐level nitride doping in the oxide, which is formed by the annealing of nitric oxide on SiO2/Si. The gate oxide thickness measured by the TOF‐SIMS profiling method using 18O or CsO profile calibration was found to correlate very well with transmission electron microscope measurement. The nitrogen concentration in the gate oxide measured using the TOF‐SIMS method was consistent with the results obtained using the dynamic SIMS method, which is currently applied to relatively thicker oxynitride films. Copyright © 2012 John Wiley & Sons, Ltd.
New sample holder geometry for high precision isotope analyses
Authors: Peres P. , Kita N. T. , Valley J. W. , Fernandes F. , Schuhmacher M.
Published: June 2012

Secondary ion mass spectrometry is applied to a wide range of Geoscience applications because of its capability to provide direct in situ measurement of elemental and isotopic composition. The CAMECA IMS 1280 and 1280‐HR are large geometry ultra‐high sensitivity ion microprobes that provide excellent precision and reproducibility for isotope ratio measurements. A precision at the tenth permil level is routinely achieved for the measurement of 18O/16O ratio from 10 µm spots using multicollection Faraday Cups. However, analytical artifacts related to the surface topography and to the location of the analysis in the sample (X–Y effects) are known to bias the precision for isotope analysis. The X–Y effects have been investigated using a CAMECA prototype sample holder design. Results show a significant improvement in terms of reproducibility for analyses performed over a large area of the sample. Detailed analytical data using the new sample holder will be presented. Copyright © 2012 John Wiley & Sons, Ltd.
Metabolic engineering: enabling technology for biofuels production
Authors: Tai Mitchell , Stephanopoulos Gregory N.
Published: June 2012

The biofuels industry is rapidly growing with the goal of providing a sustainable fuel alternative to petroleum products. However, two challenges persist in limiting current biofuels technologies as a viable alternative: (1) the cost of feedstock and (2) the quality of the fuel. Metabolic engineering shows the potential to overcome these two challenges, enabling the bioconversion of cheaper feedstocks into improved fuels in a sustainable and environmentally friendly manner. Metabolic engineering is the systematic attempt to understand, design, and engineer cellular metabolic networks using a wide range of interdisciplinary tools and strategies. It is rapidly emerging as the enabling technology behind the development of the next generation of biofuels. Several examples of current research demonstrate how metabolic engineering has begun to contribute both novel and creative solutions toward bringing promising biofuel technologies to fruition: production of higher chain alcohols, fermentation of lignocellulosic material, and production of fatty acid derivatives. © 2012 John Wiley & Sons, Ltd.

This article is categorized under:

Bioenergy > Science and Materials

Energy and Development > Science and Materials
Wound Healing after Open Appendectomies in Adult Patients: A Prospective, Randomised Trial Comparing Two Methods of Wound Closure
Authors: Kotaluoto S. , Pauniaho S.‐L. , Helminen M. , Kuokkanen H. , Rantanen T.
Published: June 2012

Background

The skin is closed in open appendectomy traditionally with few interrupted nonabsorbable sutures. The use of this old method is based on a suggestion that this technique decreases wound infections. In pediatric surgery, skin closure with running intradermal absorbable sutures has been found to be as safe as nonabsorbable sutures, even in complicated cases. Our purpose was to compare the safety of classic interrupted nonabsorbable skin closure to continuous intradermal absorbable sutures in appendectomy wounds in adult patients.

Methods

A total of 206 adult patients with clinically suspected appendicitis were allocated to the study and prospectively randomized into two groups of wound closure: the interrupted nonabsorbable (NA) suture and the intradermal continuous absorbable (A) suture group. Primary wound healing was controlled on the first postoperative day, at 1 week clinically and after 2 weeks by means of a telephone interview. Follow‐up data were obtained from 185 patients (90 in group NA and 95 in group A).

Results

Continuous absorbable intradermal suturing was as safe as nonabsorbable sutures in regard to wound infections.

Conclusion

Continuous, absorbable sutures can be used safely even in complicated appendicectomies without increasing the risk of wound infection. Considering the benefits of absorbable suturing, we recommend this method in all open appendectomies.
Enzyme replacement therapy for mucopolysaccharidosis VI: long‐term cardiac effects of galsulfase (Naglazyme®) therapy
Authors: Braunlin E. , Rosenfeld H. , Kampmann C. , Johnson J. , Beck M. , Giugliani R. , Guffon N. , Ketteridge D. , Sá Miranda C. M. , Scarpa M. , Schwartz I. V. , Leão Teles E. , Wraith J. E. , Barrios P. , Dias da Silva E. , Kurio G. , Richardson M. , Gildengorin G. , Hopwood J. J. , Imperiale M. , Schatz A. , Decker C. , Harmatz P. ,   MPS VI Study Group
Published: June 2012

Characteristic cardiac valve abnormalities and left ventricular hypertrophy are present in untreated patients with mucopolysaccharidosis type VI (MPS VI). Cardiac ultrasound was performed to investigate these findings in subjects during long‐term enzyme replacement therapy (ERT) with recombinant human arylsulfatase B (rhASB, rhN‐acetylgalactosamine 4‐sulfatase, galsulfase, Naglazyme®). Studies were conducted in 54 subjects before ERT was begun and at specific intervals for up to 96 weeks of weekly infusions of rhASB at 1 mg/kg during phase 1/2, phase 2, and phase 3 trials of rhASB. At baseline, mitral and aortic valve obstruction was present and was significantly greater in those ≥12 years of age. Mild mitral and trace aortic regurgitation were present, the former being significantly greater in those <12 years. Left ventricular hypertrophy, with averaged z‐scores ranging from 1.6–1.9 SD greater than normal, was present for ages both <12 and ≥12 years. After 96 weeks of ERT, ventricular septal hypertrophy regressed in those <12 years. For those ≥12 years, septal hypertrophy was unchanged, and aortic regurgitation increased statistically but not physiologically. Obstructive gradients across mitral and aortic valves remained unchanged. The results suggest that long‐term ERT is effective in reducing intraventricular septal hypertrophy and preventing progression of cardiac valve abnormalities when administered to those <12 years of age.
Colloidal stability of polymeric nanoparticles in biological fluids
Authors: Lazzari Stefano , Moscatelli Davide , Codari Fabio , Salmona Mario , Morbidelli Massimo , Diomede Luisa
Published: June 2012

Estimating the colloidal stability of polymeric nanoparticles (NPs) in biological environments is critical for designing optimal preparations and to clarify the fate of these devices after administration. To characterize and quantify the physical stability of nanodevices suitable for biomedical applications, spherical NPs composed of poly-lactic acid (PLA) and poly-methyl-methacrylate (PMMA), in the range 100–200 nm, were prepared. Their stability in salt solutions, biological fluids, serum and tissue homogenates was analyzed by dynamic light scattering (DLS). The PMMA NPs remained stable in all fluids, while PLA NPs aggregated in gastric juice and spleen homogenate. The proposed stability test is therefore useful to see in advance whether NPs might aggregate when administered in vivo. To assess colloidal stability ex vivo as well, spectrophotofluorimetric analysis was employed, giving comparable results to DLS.
Adventitious sprouting enables the invasive annual herb Euphorbia geniculata to regenerate after severe injury
Authors: Malíková Lenka , Mudrák Ondřej , Klimešová Jitka
Published: June 2012

Euphorbia geniculata, an annual weed of arable land native to America and invasive in subtropical and tropical regions, is able to regenerate from seeds and is also able to produce adventitious buds on the hypocotyl. Whether sprouting from adventitious buds represents a mechanism for surviving severe injury, and whether this ability is crucial for species invasion is, however, not known. The significance of such sprouting was investigated with a field survey and a pot experiment. Among 897 plants in 25 field populations surveyed in Indonesia, only a few exhibited marks of injury and sprouting from adventitious buds. When seeds were collected from 12 of the populations and used in a pot experiment, however, the seedlings were able to survive severe injury (removal of all tissue above the hypocotyl) by sprouting from adventitious buds on the hypocotyl and were able to set seed, although they produced less vegetative and generative (flowers and fruits) biomass than control plants. Growth but not fitness of plants in the pot experiment was population specific but neither growth characteristic correlated with disturbance level assessed in the field. Although the pot experiment indicates that E. geniculata can cope with severe injury by adventitious sprouting from the hypocotyl, the survey data are inconsistent with the hypothesis that such adventitious sprouting is important for the plant's invasion in tropical regions.
Alkanol‐Induced Micelles of a Very Hydrophilic EO–PO–EO Block Copolymer: Characterization by Spectral and Scattering Methods
Authors: Parmar Arpan , Bharatiya Bhavesh , Patel Keyur , Aswal Vinod , Bahadur Pratap
Published: June 2012

The aqueous solution behavior of a PEO–PPO–PEO block copolymer (EO103PO39EO103), was investigated in the presence of aliphatic alkanols (C2, C4, C6 and C8). The non‐associated polymer chains remain extremely hydrated in water, but aggregation in the form of spherical micelles was evidenced, triggered by the interaction of polymer chains with hydrophobic alkanol. We assume that the hydrophobic interaction between the PPO block of the copolymer and alkanol promotes micellization, which increases further with the introduction of higher chain length species. The critical micellization temperature (CMT), as measured by UV–visible spectroscopy, indicates an interaction of polymer chains with the alkanol bearing a higher chain length, which triggers aggregation. The micelles were characterized by small angle neutron scattering to elucidate the size and related micellar parameters. The gradual increase in the alkanol content increases the aggregation number, though the micelles were spherical in shape. We conclude that ethanol, due to its preferential solubility in the aqueous phase, does not affect the aggregation. The alkanols with chain lengths of C4–C8 chain, interact with the PPO block through hydrophobic interaction and shifts the CMTs to lower values. The combined effect of inorganic salt (NaCl) and alkanols show enhanced micellar properties.
Synthesis and Surface Activities of Novel Succinic Acid Monofluoroalkyl Sulfonate Surfactants
Authors: Zhang Luqing , Shi Jinhui , Xu Anhou , Geng Bing , Zhang Shuxiang
Published: June 2012

Two environmentally friendly succinic acid monofluoroalkyl sulfonate surfactants were synthesized from maleic anhydride and polyethylene glycol mono (1H,1H,7H‐dodecafluoroheptyl) ether, i.e. H(CF2)6CH2OCH2CH2OCOCH(SO3Na)CH2COOH (FEOS‐1) and H(CF2)6CH2(OCH2CH2)3OCOCH(SO3Na)CH2COOH (FEOS‐3). The obtained surfactants were characterized by FT‐IR, 1H NMR, 13C NMR and 19F NMR in detail. The synthesized fluorinated surfactants have a high thermal stability on the basis of thermogravimetric analysis. Their surface properties were examined and the results show that FEOS‐1 and FEOS‐3 surfactants can reduce the surface tension of water to 25.55 mN m−1 at 10.25 mmol L−1 and 21.63 mN m−1 at 8.33 mmol L−1, respectively; meanwhile, the introduction of oxyethylene groups enhances the hydrophilicity and micellar forming ability and the longer oxyethylene chains the better surface properties. The Krafft points (Kp) of FEOS‐1 and FEOS‐3 were both below 0 °C, which was lower than perfluoro‐n‐heptanesulfonic acid sodium salt (n‐C7F15SO3Na, Kp = 56.5 °C) at a similar length of fluorocarbon chains. Comparison studies on two surfactants above and the conventional fluorocarbon surfactants, perfluorooctanoate of ammonium (PFOA) show that the surfactants have comparable properties to PFOA, thus offering an environmentally friendly synthesizing alternatives to PFOA.
Bioactive Glass 45S5 Powders: Effect of Synthesis Route and Resultant Surface Chemistry and Crystallinity on Protein Adsorption from Human Plasma
Authors: Bahniuk Markian S. , Pirayesh Hamidreza , Singh Harsh D. , Nychka John A. , Unsworth Larry D.
Published: June 2012

Despite its medical applications, the mechanisms responsible for the osseointegration of bioactive glass (45S5) have yet to be fully understood. Evidence suggests that the strongest predictor for osseointegration of bioactive glasses, and ceramics, with bone tissue as the formation of an apatitic calcium phosphate layer atop the implanted material, with osteoblasts being the main mediator for new bone formation. Most have tried to understand the formation of this apatitic calcium phosphate layer, and other bioresponses between the host and bioactive glass 45S5 using Simulated Body Fluid; a solution containing ion concentrations similar to that found in human plasma without the presence of proteins. However, it is likely that cell attachment is probably largely mediated via the adsorbed protein layer. Plasma protein adsorption at the tissue bioactive glass interface has been largely overlooked. Herein, we compare crystalline and amorphous bioactive glass 45S5, in both melt-derived as well as sol–gel forms. Thus, allowing for a detailed understanding of both the role of crystallinity and powder morphology on surface ions, and plasma protein adsorption. It was found that sol–gel 45S5 powders, regardless of crystallinity, adsorbed 3–5 times as much protein as the crystalline melt-derived counterpart, as well as a greater variety of plasma proteins. The devitrification of melt-cast 45S5 resulted in only small differences in the amount and variety of the adsorbed proteome. Surface properties, and not material crystallinity, play a role in directing protein adsorption phenomena for bioactive glasses given the differences found between crystalline melt-cast 45S5 and sol–gel derived 45S5.
A neuronal transmembrane protein LRFN4 complexes with 14‐3‐3s and NCK1 to induce morphological change in monocytic cells via Rac1‐mediated actin cytoskeleton reorganization
Authors: Konakahara Shu , Suzuki Yuki , Kawakami Takao , Saitou Maki , Kajikawa Masunori , Masuho Yasuhiko , Kohroki Junya
Published: June 2012

LRFN4
physically interacts with
14‐3‐3 gamma
,
14‐3‐3 zeta/delta
,
14‐3‐3 epsilon
,
14‐3‐3 eta
and
14‐3‐3 theta
by anti tag coimmunoprecipitation (
View interaction)
Neuroprotective effects of nimodipine and nifedipine in the NGF‐differentiated PC12 cells exposed to oxygen‐glucose deprivation or trophic withdrawal
Authors: Lecht Shimon , Rotfeld Elena , Arien‐Zakay Hadar , Tabakman Rinat , Matzner Henry , Yaka Rami , Lelkes Peter I. , Lazarovici Philip
Published: June 2012

The goal of this study was to compare the neuroprotective properties of the l‐type Ca2+ channel blockers, nimodipine and nifedipine, using nerve growth factor (NGF)‐differentiated PC12 neuronal cultures exposed to oxygen‐glucose deprivation (OGD) and trophic withdrawal‐induced cell death. Nimodipine (1–100 μM) conferred 65 ± 13% neuroprotection upon exposure to OGD and 35 ± 6% neuroprotection towards different trophic withdrawal‐induced cell death measured by lactate dehydrogenase and caspase 3 activities. The time window of nimodipine conferred neuroprotection was detected during the first 5 h but not at longer OGD exposures. Nifedipine (1–100 μM), to a lower potency than nimodipine, conferred 30–55 ± 8% neuroprotection towards OGD in PC12 cells and 29 ± 5% in rat hypocampal slices, and 10 ± 3% neuroprotection at 100 μM towards trophic withdrawal‐induced PC12 cell death. The ability to demonstrate that nimodipine conferred neuroprotection in a narrow therapeutic time‐window indicates that the OGD PC12 model mimics the in vivo models and therefore suitable for neuroprotective drug discovery and development.
Sea-level history of past interglacial periods from uranium-series dating of corals, Curaçao, Leeward Antilles islands
Authors: Muhs Daniel R. , Pandolfi John M. , Simmons Kathleen R. , Schumann R. Randall
Published: June 2012

Curaçao has reef terraces with the potential to provide sea-level histories of interglacial periods. Ages of the Hato (upper) unit of the “Lower Terrace” indicate that this reef dates to the last interglacial period, Marine Isotope Stage (MIS) 5.5. On Curaçao, this high sea stand lasted at least 8000 yr (~ 126 to ~ 118 ka). Elevations and age of this reef show that late Quaternary uplift rates on Curaçao are low, 0.026–0.054 m/ka, consistent with its tectonic setting. Ages of ~ 200 ka for corals from the older Cortalein unit of the Lower Terrace correlate this reef to MIS 7, with paleo-sea level estimates ranging from − 3.3 m to + 2.3 m. The estimates are in agreement with those for MIS 7 made from other localities and indicate that the penultimate interglacial period was a time of significant warmth, on a par with the present interglacial period. The ~ 400 ka (MIS 11) Middle Terrace I on Curaçao, dated by others, may have formed from a paleo-sea level of + 8.3 to + 10.0 m, or (less likely) + 17 m to + 20 m. The lower estimates are conservative compared to previous studies, but still require major ice sheet loss from Greenland and Antarctica.
First detection of summer blue jets and starters over Northern Kanto area of Japan: Lightning activity
Authors: Suzuki Tomoyuki , Hayakawa Masashi , Hobara Yasuhide , Kusunoki Kenichi
Published: June 2012

Numerous summer blue jets and blue starters were observed for the first time over the Northern Kanto area of Japan on 15 August 2008. Sixty jets and starters were observed, and emissions continued intermittently for more than 20 min. Very high frequency (VHF) and low‐frequency (LF) lightning activity and extremely low frequency (ELF) transients associated with these phenomena were analyzed during the 5 s before and after their appearance. We found the following unique characteristics of lightning accompanied by jets/starters: (1) the interval of emissions was different for jets and starters; (2) the jets were strongly connected with negative cloud‐to‐ground lightning discharges (–CGs), but starters might have been more affected by intra‐cloud discharges (ICs); (3) the number of –CGs and ICs quickly increased just before a jet and showed a significant reduction after the jet; (4) the –CG activities began to decay 0.5 s before a starter, although IC activities were very active ±1 s of a starter; (5) the charge moment change within ±1 s of the jets and starters, as calculated from ELF transients associated with CGs, were ∼−200 and ∼−100 C⋅km, respectively; (6) the lightning discharges with jets/starters are clustered in a limited area of overshooting storm top. These results indicate that the same thunderstorm produced both a jet and a starter. This led us to hypothesize that the emittance of either a jet or starter is dependent on the amount of accumulated positive charge and the electrical activities of the parent storm.
Short‐term variability in Greenland Ice Sheet motion forced by time‐varying meltwater drainage: Implications for the relationship between subglacial drainage system behavior and ice velocity
Authors: Bartholomew Ian , Nienow Peter , Sole Andrew , Mair Douglas , Cowton Thomas , King Matt A.
Published: June 2012

High resolution measurements of ice motion along a ∼120 km transect in a land‐terminating section of the GrIS reveal short‐term velocity variations (<1 day), which are forced by rapid variations in meltwater input to the subglacial drainage system from the ice sheet surface. The seasonal changes in ice velocity at low elevations (<1000 m) are dominated by events lasting from 1 day to 1 week, although daily cycles are largely absent at higher elevations, reflecting different patterns of meltwater input. Using a simple model of subglacial conduit behavior we show that the seasonal record of ice velocity can be understood in terms of a time‐varying water input to a channelized subglacial drainage system. Our investigation substantiates arguments that variability in theduration and rate, rather than absolute volume, of meltwater delivery to the subglacial drainage system are important controls on seasonal patterns of subglacial water pressure, and therefore ice velocity. We suggest that interpretations of hydro‐dynamic behavior in land‐terminating sections of the GrIS margin which rely on steady state drainage theories are unsuitable for making predictions about the effect of increased summer ablation on future rates of ice motion.
Seismic multiplet response triggered by melt at Blood Falls, Taylor Glacier, Antarctica
Authors: Carmichael Joshua D. , Pettit Erin C. , Hoffman Matt , Fountain Andrew , Hallet Bernard
Published: June 2012

Meltwater input often triggers a seismic response from glaciers and ice sheets. It is difficult, however, to measure melt production on glaciers directly, while subglacial water storage is not directly observable. Therefore, we document temporal changes in seismicity from a dry‐based polar glacier (Taylor Glacier, Antarctica) during a melt season using a synthesis of seismic observation and melt modeling. We record icequakes using a dense six‐receiver network of three‐component geophones and compare this with melt input generated from a calibrated surface energy balance model. In the absence of modeled surface melt, we find that seismicity is well‐described by a diurnal signal composed of microseismic events in lake and glacial ice. During melt events, the diurnal signal is suppressed and seismicity is instead characterized by large glacial icequakes. We perform network‐based correlation and clustering analyses of seismic record sections and determine that 18% of melt‐season icequakes are repetitive (multiplets). The epicentral locations for these multiplets suggest that they are triggered by meltwater produced near a brine seep known as Blood Falls. Our observations of the correspondingp‐wave first motions are consistent with volumetric source mechanisms. We suggest that surface melt enables a persistent pathway through this cold ice to an englacial fracture system that is responsible for brine release episodes from the Blood Falls seep. The scalar moments for these events suggest that the volumetric increase at the source region can be explained by melt input.
The role of trace gas flux networks in the biogeosciences
Authors: Baldocchi Dennis , Reichstein Markus , Papale Dario , Koteen Laurie , Vargas Rodrigo , Agarwal Deborah , Cook Robert
Published: June 2012

Vast networks of meteorological sensors ring the globe, providing continuous measurements of an array of atmospheric state variables such as temperature, humidity, rainfall, and the concentration of carbon dioxide [New et al., 1999; Tans et al., 1996]. These measurements provide input to weather and climate models and are key to detecting trends in climate, greenhouse gases, and air pollution. Yet to understand how and why these atmospheric state variables vary in time and space, biogeoscientists need to know where, when, and at what rates important gases are flowing between the land and the atmosphere. Tracking trace gas fluxes provides information on plant or microbial metabolism and climate‐ecosystem interactions.
Keir receives 2011 Jason Morgan Early Career Award: Response
Authors: Keir Derek
Published: June 2012

Derek Keir received the 2011 Jason Morgan Early Career Award at the 2011 AGU Fall Meeting, held 5–9 December in San Francisco, Calif. The award is for significant early‐career contributions in tectonophysics.