bluuebunny/crossref_metadata_2025_split huggingface dataset:
The quality is in the eye of the beholder: The perspective of FTIR and UV resonant Raman spectroscopies on extracted nucleic acids
Authors: Zucchiatti P. , Latella K. , Birarda G. , Vaccari L. , Rossi B. , Gessini A. , Masciovecchio C. , D'Amico F. 
Published: January 2018

AbstractThe quality of a sample has always to be considered with respect to its purposes and to the technique used for assessing it. The aim of this work is to point out the most common interfering agents that vibrational spectroscopists may find when analyzing nucleic acids extracted from cellular cultures. Fourier transformed infrared and ultraviolet‐resonant Raman measurements have been carried out on DNA and RNA samples extracted from B16 cell cultures by standard protocols used in molecular biology. The routinely adopted quality control procedure, based on ultraviolet spectrophotometry absorption measurements, could only indicate the absence of protein, phenol, or other contaminants that absorb strongly at or near 280 nm. However, DNA and RNA samples of good quality from a biological perspective clearly showed the presence of chemicals interfering with the vibrational measurements, mainly ethanol and guanidinium salts. Here, we propose fast and inexpensive strategies for tailoring the extraction protocols in light of the requirements of both vibrational spectroscopies that allowed obtaining nucleic acid samples with ethanol concentration below the detection limit of both techniques and with a significantly reduced spectral interference from guanidinium salts.
Responses of the large centric diatom Coscinodiscus sp. to interactions between warming, elevated CO2, and nitrate availability
Authors: Qu Pingping , Fu Feixue , Hutchins David A. 
Published: January 2018

AbstractMarine ecosystems are facing multiple anthropogenic global changes, including ocean acidification, warming, and reduced nutrient supplies. Together, these will challenge phytoplankton including large centric diatoms such as Coscinodiscus sp., a group that is important to ocean food webs and carbon export. We investigated the interactive effects of warming, elevated CO2, and nitrate availability on Coscinodiscus growth, elemental stoichiometry, and Fe and C uptake rates in a four‐treatment factorial experiment combining two CO2 levels (∼400 ppm and 800 ppm) and two temperatures (16°C and 20°C) across seven nitrate concentrations (1–100 μmol L−1). Higher temperatures led to higher maximum growth rates (μmax), but also higher half‐saturation constants for nitrate (K1/2), while elevated CO2 increased K1/2 only at the warmer temperature. Lower μmax/K1/2 ratios under warming and rising CO2 indicated a higher nitrate requirement at these conditions. High temperature decreased cellular P and Si contents and consequently increased N : P and C : Si ratios, especially at ambient CO2. Fe : C uptake ratios responded positively to lower nitrate levels, lower CO2, and warming. Significant interactions between nitrate availability and temperature or CO2 were observed for specific growth rates, chlorophyll a and Si contents, Fe : C, N : P, and Si : C, while temperature and CO2 interactions were only significant for μmax/K1/2 and cellular P content. The mutual interactions among CO2 concentrations, temperature, and nitrate supply may all affect future growth, physiology, and carbon export by Coscinodiscus sp., however, in general warming and nitrate availability appear to be more influential than CO2.
Investigation of rheological and mechanical properties of wood flour reinforced polypropylene
Authors: Güldaş A. , Zeyveli M. , Kaya S. , Altuğ M. 
Published: January 2018

AbstractThis study aims to investigate the rheological and mechanical properties of polypropylene when reinforced by wood flour. In the study, wood flour (WF) was added as filling material to polypropylene (PP), and its effects were investigated. The grain size of the wood flour was 300 μm. Wood flour was mixed into polypropylene material at different rates of weight. Viscosity changes of the polypropylene at various temperatures and pressure values of the concentration rates were documented. As a result, viscosity increases as the amount of wood flour filling is increased; yet as temperature, pressure and shear rate are increased, viscosity decreases. The study also focuses on the changes in its mechanical properties of polypropylene reinforced with wood flour. The tensile strength of reinforced polypropylene at varying percentages (wt. 5 %, wt. 10 % and wt. 15 %) was observed to decrease by 11 %, 16 % and 21 %, respectively, compared to that of non‐reinforced polypropylene. Additionally, impact tests showed that the highest energy absorption was in 10 % wood flour reinforced polypropylene.
Isotropic resolution diffusion tensor imaging of lumbosacral and sciatic nerves using a phase‐corrected diffusion‐prepared 3D turbo spin echo
Authors: Cervantes Barbara , Van Anh T. , Weidlich Dominik , Kooijman Hendrick , Hock Andreas , Rummeny Ernst J. , Gersing Alexandra , Kirschke Jan S. , Karampinos Dimitrios C. 
Published: January 2018

PurposeTo perform in vivo isotropic‐resolution diffusion tensor imaging (DTI) of lumbosacral and sciatic nerves with a phase‐navigated diffusion‐prepared (DP) 3D turbo spin echo (TSE) acquisition and modified reconstruction incorporating intershot phase‐error correction and to investigate the improvement on image quality and diffusion quantification with the proposed phase correction.MethodsPhase‐navigated DP 3D TSE included magnitude stabilizers to minimize motion and eddy‐current effects on the signal magnitude. Phase navigation of motion‐induced phase errors was introduced before readout in 3D TSE. DTI of lower back nerves was performed in vivo using 3D TSE and single‐shot echo planar imaging (ss‐EPI) in 13 subjects. Diffusion data were phase‐corrected per kz plane with respect to T2‐weighted data. The effects of motion‐induced phase errors on DTI quantification was assessed for 3D TSE and compared with ss‐EPI.ResultsNon–phase‐corrected 3D TSE resulted in artifacts in diffusion‐weighted images and overestimated DTI parameters in the sciatic nerve (mean diffusivity [MD] = 2.06 ± 0.45). Phase correction of 3D TSE DTI data resulted in reductions in all DTI parameters (MD = 1.73 ± 0.26) of statistical significance (P ≤ 0.001) and in closer agreement with ss‐EPI DTI parameters (MD = 1.62 ± 0.21).ConclusionDP 3D TSE with phase correction allows distortion‐free isotropic diffusion imaging of lower back nerves with robustness to motion‐induced artifacts and DTI quantification errors. Magn Reson Med 80:609–618, 2018. © 2018 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
Convergence of iterative methods based on Neumann series for composite materials: Theory and practice
Authors: Moulinec Hervé , Suquet Pierre , Milton Graeme W. 
Published: January 2018

SummaryIterative fast Fourier transform methods are useful for calculating the fields in composite materials and their macroscopic response. By iterating back and forth until convergence, the differential constraints are satisfied in Fourier space and the constitutive law in real space. The methods correspond to series expansions of appropriate operators and to series expansions for the effective tensor as a function of the component moduli. It is shown that the singularity structure of this function can shed much light on the convergence properties of the iterative fast Fourier transform methods. We look at a model example of a square array of conducting square inclusions for which there is an exact formula for the effective conductivity (Obnosov). Theoretically, some of the methods converge when the inclusions have zero or even negative conductivity. However, the numerics do not always confirm this extended range of convergence and show that accuracy is lost after relatively few iterations. There is little point in iterating beyond this. Accuracy improves when the grid size is reduced, showing that the discrepancy is linked to the discretization. Finally, it is shown that none of the 3 iterative schemes investigated overperforms the others for all possible microstructures and all contrasts.
Ultraviolet light and melanoma
Authors: Craig Sarah , Earnshaw Charles H , Virós Amaya 
Published: January 2018

AbstractMelanoma is a clinically heterogeneous disease, and current strategies for treatment of the primary tumour are based on pathological criteria alone. In the recent past, several DNA‐sequencing and RNA‐sequencing studies of primary and advanced melanoma samples have identified unique relationships between somatic mutations, genomic aberrations, and the genetic fingerprint of ultraviolet radiation (UVR). The recurrent patterns of genomic alterations reveal different disease pathways, drug targets and mechanisms limiting drug response. Here, we examine the known associations between the molecular categories of melanoma and the multidimensional UVR damage. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Noninvasive encapsulated follicular variant of papillary thyroid carcinoma: Should it also be reclassified in children?
Authors: Mariani Rachel A. , Kadakia Rachel , Arva Nicoleta C. 
Published: January 2018

AbstractBackgroundNoninvasive encapsulated follicular variant of papillary thyroid carcinoma (noniEFVPTC) has low risk of adverse outcome in adults, warranting reclassification as noninvasive follicular thyroid neoplasm with papillary‐like nuclear features (NIFTP). In children, thyroid nodules have higher risk of malignancy and it is unknown if encapsulated FVPTC (EFVPTC) and infiltrative FVPTC (IFVPTC) tumors have different behavior. We analyzed the clinicopathologic features of follicular variant of papillary thyroid carcinoma (FVPTC) subtypes in our pediatric population to determine if noniEFVPTC has an indolent course as reported in adults.ProcedureWe retrospectively studied all patients diagnosed with FVPTC at our institution. The clinicopathologic characteristics of the histologic subtypes were compared.ResultsEighteen patients were identified, all treated with total thyroidectomy. No significant differences in age, sex, tumor size, focality, or prior malignancy were detected between subtypes. Extrathyroidal extension had significantly higher incidence in IFVPTC (5/8) compared with EFVPTC (1/10, P = 0.03), translating in significantly more T3 tumors within IFVPTC subtype (5/8), whereas most EFVPTC cases had T1 staging (6/10, T1 vs. T3, P = 0.05). EFVPTC had significantly lower rate of lymph node involvement (N1 in 2/8) compared with IFVPTC (N1 in 8/8, P = 0.003). Only one patient diagnosed with IFVPTC developed extranodal recurrence. When noniEFVPTC and iEFVPTC were separately compared, the noninvasive form showed no propensity for invasive growth (T3 staging: 0/4 vs. 2/6), lymph node metastasis (N1: 0/3 vs. 2/5) or extranodal recurrence.ConclusionIn children, noniEFVPTC/NIFTP has indolent behavior, warranting consideration of less aggressive management, similar to adults.
Early outcomes and patterns of failure following proton therapy for nonmetastatic intracranial nongerminomatous germ cell tumors
Authors: Mokhtech Meriem , Rotondo Ronny L. , Bradley Julie A. , Sandler Eric S. , Nanda Ronica , Logie Natalie , Aldana Philipp R. , Morris Christopher G. , Indelicato Daniel J. 
Published: January 2018

AbstractBackgroundAlthough dosimetric comparisons demonstrate the advantage of proton therapy (PT) over conventional radiotherapy for nongerminomatous germ cell tumors (NGGCT), clinical outcome data for this rare tumor are lacking. We sought to evaluate outcomes for children with NGGCT treated with PT.MethodsBetween 2007 and 2016, 14 children (median age 11, range, 5–19 years) with nonmetastatic NGGCT were treated with PT after induction chemotherapy. Most (8/14) were mixed germ cell. Five of 14 patients had complete resection of their primary tumor before radiation. Off study, eight patients received 36 Gy (RBE [relative biological effectiveness]) craniospinal irradiation (CSI). On study, two patients received 30.6 Gy (RBE) whole‐ventricle irradiation and four received focal radiation alone. All patients received a total dose of 54 Gy (RBE) to the tumor/tumor bed.ResultsAt a median follow‐up of 2.8 years, all patients were alive with no local recurrences. Three‐year progression‐free survival was 86%. Both metastatic recurrences occurred in patients treated with focal radiation alone; one with an immature teratoma developed an isolated spinal recurrence 5 months after treatment. Another with a mixed germ cell tumor developed a multifocal ventricular and shunt tract recurrence 7 months after treatment. Serious toxicity was minimal, including cataracts and hormone deficiency, and limited to children who received CSI.ConclusionEarly outcomes in children treated for NGGCT suggest the high conformality of PT does not compromise disease control and yields low toxicity. This pattern of failure data adds to growing evidence suggesting chemotherapy followed by focal radiotherapy alone is inadequate in controlling localized NGGCT.
New statin use and left ventricular structure: Estimating long‐term associations in the Multi‐Ethnic Study of Atherosclerosis (MESA)
Authors: Strand Lauren N. , Young Rebekah L. , Bertoni Alain G. , Bluemke David A. , Burke Gregory L. , Lima Joao A. , Sotoodehnia Nona , Psaty Bruce M. , McClelland Robyn L. , Heckbert Susan R. , Delaney Joseph A. 
Published: January 2018

AbstractPurposeOnly small and short‐term studies have evaluated statins in relation to changes in heart structure. We estimated the association between new statin use and 10‐year remodeling of the left ventricle.MethodsThe Multi‐Ethnic Study of Atherosclerosis collected data on statin use over approximately 10 years, conducting cardiac magnetic resonance (CMR) imaging at baseline and the 10‐year exam. Participants were free of baseline cardiovascular disease, and we excluded users of statins at baseline. Statin initiation was defined as a report of current use at any of the 4 subsequent exams. Primary outcomes were the change in left ventricular mass index (LVMI; % predicted by height, weight, and sex) and mass‐to‐volume ratio. Associations were estimated in a propensity score‐matched analysis.ResultsA total of 3113 participants (53% female; 40% European‐American, 25% African‐American, 22% Hispanic‐American, and 13% Chinese‐American) were eligible; 2431 returned for follow‐up CMR imaging after a median of 9.4 years. Statin therapy (moderate dose, 76%) was started by 36% of participants (N = 872). We excluded 42 participants with incident myocardial infarction. Compared with nonuse, statin use was associated with less 10‐year progression in LVMI (−2.35 percentage points; 95% CI, −4.24 to −0.47; P = .01) and mass‐to‐volume ratio (−0.03 absolute difference; 95% CI, −0.07 to −0.00; P = .02); effects were small in magnitude. A dose response was observed: Higher statin dose was associated with less LVMI progression.ConclusionsIn contrast to previous small studies, we found very modest associations between statin use and indices of left ventricular remodeling over 10 years in this prospective study of a diverse cohort.
Mechanistic insights into N‐heterocyclic carbene (NHC)‐catalyzed N‐acylation of N‐sulfonylcarboxamides with aldehydes
Authors: Gao Jinxin , Zhao Pengtao , Qiao Yan , Li Hua 
Published: January 2018

AbstractIn the current work, density functional theory calculations were performed to elucidate the detailed reaction mechanism for N‐heterocyclic carbene (NHC)‐catalyzed oxidative N‐acylation reaction of amides with aldehydes affording imide products. According to the calculated results, the reaction is initiated by the nucleophilic attack of NHC to aldehydes forming zwitterionic intermediate, which can then form Breslow intermediate via proton transfer. The Breslow intermediate can then be oxidized affording the oxidative intermediate, which can then go through 1,2‐addition with the deprotonated N‐sulfonylcarboxamides. Subsequently, elimination of NHC catalyst produces the final imide product. Our results reveal that the proton in N‐sulfonylcarboxamides is probably abstracted by base t‐BuOK or DPQH, and the deprotonation process is barrier‐less. Moreover, for the second step, ie, the formation of Breslow intermediate, direct proton transfer is impossible to occur. On the contrary, the results reveal that t‐BuOH can mediate the proton transfer in this step and significantly lower the energy barrier to 24.1 kcal/mol, which is also the highest energy barrier for the whole reaction. The work provides not only valuable clues for elucidating the detailed reaction mechanism for the invaluable NHC‐catalyzed oxidative reactions but also mechanistic insights for the rational design of novel NHC‐catalyzed oxidative reactions in the future.
Polarons radical polymerization
Authors: Yamabe Kohei , Nakajima Kuniharu , Goto Hiromasa 
Published: January 2018

ABSTRACTPolystyrene has been typically prepared with radical polymerization by benzoyl peroxide (BPO) or azobisisobutyronitrile (AIBN). In this report, polymerization of styrene was carried out by radical cations of polyaniline (PANI). Polarons of conducting polymers are consisting of radical cations. The polarons bear electrical conduction as a charge carrier. We employ the polarons as an initiator for radical polymerization. Polymerization of styrene and acrylonitrile by the polarons was conducted to explore new possibility of conducting polymers. Fourier‐transfer infrared absorption (FTIR) spectroscopy measurements for the resultant polymers obtained with polarons of polyaniline indicates that the polystyrene thus synthesized grows from polyaniline. The qualitative solubility, average molecular weight, and thermal stability are comparable to that of polystyrene obtained by the common method with BPO. Radical polymerization by polarons may provide a new avenue for radical polymerizations through application of conducting polymer. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 805–811
Theory of polymer brushes grafted to finite surfaces
Authors: Andreu Artola Agustín Santiago , Soulé Ezequiel Rodolfo 
Published: January 2018

ABSTRACTIn this work, a model based in strong‐stretching theory for polymer brushes grafted to finite planar surfaces is developed and solved numerically for two geometries: stripe‐like and disk‐like surfaces. There is a single parameter,
, which represents the ratio between the equilibrium brush height and the grafting surface size, that controls the behavior of the system. When
is large, the system behaves as if the polymer were grafted to a single line or point and the brush adopts a cylindrical or spherical shape. In the opposite extreme when it is small, the brush behaves as semi‐infinite and can be described as a planar undeformed brush region and an edge region, and the line tension approaches a limiting value. In the intermediate case, a brush with non‐uniform height and chain tilting is observed, with a shape and line tension depending on the value of
. Relative stability of disk‐shaped, stripe‐shaped, and infinite lamellar micelles is analyzed based in this model. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 663–672
Structure–property relationships of fatty acid swollen, crosslinked natural rubber shape memory polymers
Authors: Pantoja Marcos , Lin Zhiwei , Cakmak Mukerrem , Cavicchi Kevin A. 
Published: January 2018

ABSTRACTThis article investigates shape memory polymers (SMPs) fabricated by swelling sulfur crosslinked natural rubber with four different molten fatty acids: lauric, myristic, palmitic, and stearic acid. As inexpensive additives, they allow commodity natural rubber to be directly converted to SMPs. The shape memory properties are investigated as a function of wt% fatty acid, the choice of fatty acid, and the applied load during shape memory programming. It is found that increasing the wt% acid improves the shape fixity up to ca. 97% at ≥50 wt% fatty acid, at which point the recovery starts to decline with increasing wt% acid due to network failure during shape programming. The shape fixity is found to depend on the yield stress and modulus of the fatty acid network, which both increase with increasing wt% acid. The choice of fatty acid also varies the trigger temperature for shape memory, which scales with the melting point of the fatty acid. Serendipitously, it is found that alignment of the fatty acid crystals during programming produces stiffer networks whose modulus increase with applied load, which counterbalances the higher elastic energy stored in the rubber network to produce lower sensitivity of the shape fixity to the applied load. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys.2018,56, 673–687
Engineered control of enzyme structural dynamics and function
Authors: Boehr David D. , D'Amico Rebecca N. , O'Rourke Kathleen F. 
Published: January 2018

AbstractEnzymes undergo a range of internal motions from local, active site fluctuations to large‐scale, global conformational changes. These motions are often important for enzyme function, including in ligand binding and dissociation and even preparing the active site for chemical catalysis. Protein engineering efforts have been directed towards manipulating enzyme structural dynamics and conformational changes, including targeting specific amino acid interactions and creation of chimeric enzymes with new regulatory functions. Post‐translational covalent modification can provide an additional level of enzyme control. These studies have not only provided insights into the functional role of protein motions, but they offer opportunities to create stimulus‐responsive enzymes. These enzymes can be engineered to respond to a number of external stimuli, including light, pH, and the presence of novel allosteric modulators. Altogether, the ability to engineer and control enzyme structural dynamics can provide new tools for biotechnology and medicine.