bluuebunny/crossref_metadata_2025_split huggingface dataset:
Soil biological activity as affected by tillage intensity
Authors: Gajda A. , Przewłoka B. 
Published: March 2012

Soil biological activity as affected by tillage intensityThe effect of tillage intensity on changes of microbiological activity and content of particulate organic matter in soil under winter wheat duirng 3 years was studied. Microbial response related to the tillage-induced changes in soil determined on the content of biomass C and N, the rate of CO2evolution, B/F ratio, the activity of dehydrogenases, acid and alkaline phosphatases, soil C/N ratio and microbial biomass C/N ratio confirmed the high sensitivity of soil microbial populations to the tillage system applied. After three year studies, the direct sowing system enhanced the increase of labile fraction of organic matter content in soil. There were no significant changes in the labile fraction quantity observed in soil under conventional tillage. Similar response related to the tillage intensity was observed in particulate organic matter quantities expressed as a percentage of total organic matter in soil. A high correlation coefficients calculated between contents of soil microbial biomass C and N, particulate organic matter and potentially mineralizable N, and the obtained yields of winter wheat grown on experimental fields indicated on a high importance of biological quality of status of soil for agricultural crop production.
Overview of Radical Initiation
Authors: Lalevée Jacques , Fouassier Jean Pierre 
Published: March 2012

AbstractFree radicals are key intermediates in many chemical or biological processes and are characterized by a growing number of applications. Convenient methods are requested for the clean generation of these intermediates that can be further used as initiating species in various chemical reactions. Radical initiators correspond to compounds that can produce free radicals under mild conditions to promote radical reactions. In this article, the principal routes for radical initiation are described. The different activation pathways (thermolysis, photolysis, and radiolysis) are presented and various examples and different parameters characterizing radical initiator properties are provided (decomposition rates, bond dissociation energies, spectral sensitivity, etc.). Redox processes leading to the generation of free radical are also presented.
Radiation‐Induced Radical Reactions
Authors: Bobrowski Krzysztof 
Published: March 2012

AbstractThis article reports on radiation‐induced radical reactions in gases, liquids, and solids. A brief summary of specific features of high‐energy radiation and its interaction with matter is given as a base for better understanding of reaction mechanisms initiated by radiation. The first section describes the most important features of radiolysis in a gas phase with presentation of the commonly used gas systems for inducing and studying radical reactions. Relevant examples include radical reactions connected with atmospheric and environmental chemistry, combustion, and electric discharges. The second section focuses on radiation‐induced radical reactions in water and aqueous solutions with a special emphasis on procedures that allow induction of radical reactions in a controlled manner. Relevant examples include radical reactions initiated by primary and secondary radicals from water radiolysis with a variety of compounds. Application of various organic solvents and ionic liquids offering a convenient method of generation and also some control over the nature of radical ions and excited states formed in the irradiated solvents and derived from the solutes is also presented. The last section briefly summarizes the most commonly applied solid systems and highlights radiation‐induced radical reactions in zeolites, a new matrix used recently for radiation generation of radicals and radical ions in the solid state.
Organic Electron Donors
Authors: Murphy John A. 
Published: March 2012

Abstract
One of the most prevalent methods of forming radicals involves oxidation of closed‐shell organic molecules to radical cations, followed by loss of a proton or other positively charged entity, leaving a radical. There are so many ways to trigger the loss of an electron from a neutral molecule to form a radical cation that it is not surprising that this approach has very important and widespread synthetic applications. This article examines the oxidation of neutral organic molecules under various conditions: (i) spontaneous electron transfer to a substrate, which happens with highly electron‐rich organic molecules acting as electron donors, (ii) by photoelectron transfer from a substrate to an excited state receptor, where the transfer can be either intramolecular or intermolecular, (iii) by reaction with an oxidizing reagent, and (iv) by electrochemical oxidation. By giving examples of all of these, the article aims to give an overview of organic molecules as electron donors. Notable recent developments in organocatalysis are included, featuring oxidation of enamines, as are recent developments of neutral organic super‐electron‐donors.
Halogen and Chalcogen Transfer Chemistry
Authors: Li Chaozhong 
Published: March 2012

AbstractAtom transfer reactions have become an indispensable tool for carbon–carbon bond formations. Atom transfer radical addition (ATRA) reactions were first discovered by Kharasch and coworkers in the year 1945. This type of transformations did not receive much attention until the mid‐1980s when Curranet al.first demonstrated the atom transfer radical cyclization (ATRC) reactions and their application in the synthesis of (±)‐hirsutene. Enormous progress has been made since then. Reactions involving transfer of halogens (I, Br, Cl) and chalcogens (SePh and TeAr) have been developed, providing a powerful, atom‐economic, and nonreductive complement to the tin hydride method for conducting radical addition reactions. The introduction of Lewis acids increases the efficiency and regio‐ and stereoselectivity in many cases. Transition‐metal catalysis, in combination with reducing agents, makes the ATRA and ATRC reactions more efficient and environmentally friendly. In this article, the versatile chemistry of halogen (I, Br, Cl) and chalcogen (PhSe and ArTe) transfer involving carbon–carbon bond formation is discussed.
Understanding
DNA
Radicals Employing Theory and Electron Spin Resonance Spectroscopy
Authors: Adhikary Amitava , Kumar Anil , Becker David , Sevilla Michael D. 
Published: March 2012

Abstract

Ionizing radiation, such as γ‐rays, X‐rays, or ion beam radiation, results in the formation of cation and anion radicals in DNA and neutral radicals by secondary reactions. These DNA radicals are stable at low temperatures and, therefore, can be studied by electron spin resonance (ESR) spectroscopy. In these DNA radicals, the unpaired spin on the radical site interacts with nuclei with a magnetic moment, such as,
1
H,
2
H, and
14
N. This electron spin–nuclear spin interaction gives rise to hyperfine coupling, which is characterized by the hyperfine coupling constant (HFCC) values. The HFCC values along with the

g

‐values determine the ESR spectra of these radicals. Calculations based on density functional theory (DFT) allow for identification of these DNA radicals via the prediction of stabilization energies and, most importantly, accurate values of the HFCCs. These calculations elucidate radical conformational structures as well. Thus, the combination of ESR with DFT calculations is a powerful approach to the investigation of DNA radicals and is the main focus of this article. This is illustrated in this article by specific examples—such as the prediction of sites of deprotonation in the DNA base cation radicals, intra‐base pair proton transfer processes in DNA base radicals, and excited state‐induced reactions of the DNA base cation and anion radicals leading to sugar radical formation.
Reversible Addition Fragmentation Chain Transfer (
RAFT
) Polymerization: Mechanism, Process and Applications
Authors: Barner‐Kowollik Christopher , Blinco James P. , Destarac Mathias , Thurecht Kristofer J. , Perrier Sébastien 
Published: March 2012

Abstract
The present article gives an overview of the reversible addition fragmentation chain transfer (RAFT) process. RAFT is one of the most versatile living radical polymerization systems and yields polymers of predictable chain length and narrow molecular weight distribution. RAFT relies on the rapid exchange of thiocarbonyl thio groups between growing polymeric chains. The key strengths of the RAFT process for polymer design are its high tolerance of monomer functionality and reaction conditions, the wide range of well‐controlled polymeric architectures achievable, and its (in‐principle) non‐rate‐retarding nature. This article introduces the mechanism of polymerization, the range of polymer molecular weights achievable, the range of monomers in which polymerization is controlled by RAFT, the various polymeric architectures that can be obtained, the type of end‐group functionalities available to RAFT‐made polymers, and the process of RAFT polymerization.
Atom Transfer Radical Polymerization (ATRP) and Addition (ATRA) and Applications
Authors: Pintauer Tomislav , Matyjaszewski Krzysztof 
Published: March 2012

AbstractFundamentals of transition‐metal‐catalyzed atom transfer radical polymerization (ATRP) and mechanistically similar atom transfer radical addition (ATRA) are discussed. Both processes utilize transition‐metal complexes as halogen atom transfer agents. ATRP enables the synthesis of polymeric materials with well‐controlled molecular weight, molecular weight distribution, composition, molecular architecture, and chain‐end functionality. ATRA, on the other hand, is particularly suitable for the synthesis of small and highly functional organic molecules. Basic phenomenology, components (alkyl halide, monomer, solvent, and catalyst), as well as current and forthcoming applications are reviewed.
Spin Labels and Spin Probes
Authors: Bardelang David , Hardy Micaël , Ouari Olivier , Tordo Paul 
Published: March 2012

AbstractThe electron paramagnetic resonance (EPR) parameters of a free radical depend strongly on its microenvironment and stable radicals can be used as reporter molecules for the EPR probing of various chemical and biological systems. Nowadays, nitroxides and trityl radicals are the most important spin labels or spin probes and their use in various applications, spin labeling, spin trapping, oximetry, pH measurement, evaluation of redox status, interactions in supramolecular systems, and so on, are examined.
Polyradicals in Batteries
Authors: Oyaizu Kenichi , Nishide Hiroyuki 
Published: March 2012

AbstractOrganic robust radicals are susceptible to reversible 1e−transfer reactions to yield closed‐shell molecules, giving rise to an electrochemically reversible redox response. This property has been exploited for reversible charge storage by organic polymers, allowing energy storage with an excellent rate performance. Redox properties of the organic robust radicals, together with their roles in a rechargeable device called radical battery, are reviewed.
Radical Chemistry on Fullerenes
Authors: Tzirakis Manolis D. , Orfanopoulos Michael 
Published: March 2012

Abstract

The aim of this article is to provide a concise review mainly on the practical synthetic applications and to a lesser extent on the fundamentals of fullerenes' radical chemistry. From a practical point of view, we demonstrate that the employment of radical reactions in fullerene chemistry has led to the synthesis of a variety of structurally diverse fullerene derivatives which would be otherwise inaccessible. In this context, the major types of neutral or ion radical additions to C
60
are reported. Such reactions include the addition of radicals of different chemical nature, including C‐, Si‐, O‐, S‐, P‐, and metal‐centered radicals, to C
60
or C
70
. From a fundamental perspective, we report on some of the basic characteristics of the radical reactions of fullerenes, such as the tendency of free radicals to add, multiply, and fast to C
60
and the tendency of the resulting RC
60
·
to dimerize.
Predictors of breast milk macronutrient composition in filipino mothers
Authors: Quinn Elizabeth A. , Largado Fe , Power Michael , Kuzawa Christopher W. 
Published: March 2012

AbstractObjectives:There is increasing evidence that breastfeeding has long‐term effects on offspring biology and health, which has heightened interest in understanding the extent of variation in breast milk composition and its underlying determinants. Here, we report variation in milk macronutrient composition in a well‐characterized cohort of young Filipino mothers and test underlying maternal predictors of this variation.Methods:Morning breast milk samples, anthropometrics, dietary recalls, and other interview data were collected in 102 Filipino young breastfeeding mothers (age range 24.6–25.4 years) living in Cebu City, Philippines. Milk samples were analyzed for protein, fat, sugar, and milk energy density. Regression models were used to test associations between milk macronutrient composition and maternal diet, body composition, breastfeeding duration, and feeding frequency.Results:Consistent with past studies, milk fat and energy increased with duration of breastfeeding; there were no associations between maternal diet or percent body fat and milk composition with the exception of a modest, inverse association between maternal adiposity and milk sugar content.Conclusions:The relative lack of associations between maternal diet or body composition and milk composition at Cebu is consistent with past studies and suggests that milk composition may be buffered against fluctuations in maternal dietary intake or nutritional status. We speculate that the tendency for milk composition to vary between populations faced with different nutritional ecologies, but to show minimal responsiveness to intake during lactation, may enhance the reliability of milk composition as a stable intergenerational cue of typical local environmental quality. Am. J. Hum. Biol. 2012. © 2012 Wiley Periodicals, Inc.
Helper effects on breeder allocations to direct care
Authors: Kushnick Geoff 
Published: March 2012

AbstractIntroduction:Mothers receive childcare and productive assistance from allomaternal helpers in many societies. Although much effort has been aimed toward showing helper effects on maternal reproductive success, less has been directed toward highlighting the full range of potential effects on breeder behavior. I present a model of optimal maternal care with helpers, and tests of derived hypotheses with data collected among the Karo Batak—a group of Indonesian agriculturalists.Methods:To test the model's predictions I compared the effect of women receiving help from patrilateral versus matrilateral kin because those kin may provide help with different maternal responsibilities. The model predicts a decrease in maternal allocation to care that is substitutable with the helper contribution and the helper assists with that type of care; it predicts an increase in care that is nonsubstitutable with the helper contribution or substitutable care when the helper assists with other responsibilities. With the exception of one other, most models have failed to account for an increase.Results/Conclusions:Analyses of time spent carrying children supported the model. With matrilateral helpers, women increased carrying; with patrilateral helpers, they decreased it. Time spent farmworking showed the opposite pattern, suggesting that matrilateral helpers effectively decrease costs, nudging optimal maternal care upward. Patterns of breastfeeding provided little support for the model. The results do, however, suggest potential proximate mechanisms by which helpers influence maternal reproductive success in cooperative breeding societies. Am. J. Hum. Biol. 2012. © 2012 Wiley Periodicals, Inc.
Organization of the gymnotiform fish pallium in relation to learning and memory: III. Intrinsic connections
Authors: Giassi Ana C.C. , Ellis William , Maler Leonard 
Published: March 2012

AbstractThe present article reports on the telencephalic connections of regions of the dorsal telencephalon of the weakly electric fish Apteronotus leptorhynchus and Gymnotus sp. that are involved in learning and memory: the lateral (DL), central (DC), and dorsal (DD) regions of the pallium and the intermediate region between DL and DC (Dx). We find that the main route of transmission consists of diencephalic (preglomerular complex; PG) glutamatergic input to DL; glutamatergic projections from DL to DC and Dx; and glutamatergic output from DC/Dx to di‐, mes‐, and rhombencephalic nuclei. Although PG efferents to DL are spatially organized, the projection from DL to DC appears to be diffuse. The connections of DD are entirely intrinsic to the pallium: DL projects to DD (glutamatergic) and DD feeds back to DL (glutamatergic); DD also projects to DC and has strong contralateral connections. In addition, DL and DD receive input from subpallial regions; we suggest that these are associated with the previously identified γ‐aminobutyric acid (GABA)‐ergic, dopaminergic, and somatostatin‐positive input to these regions. The DL/DD connections are very complex, because DL projects to and receives input from different subdivisions of DD. These subdivisions are linked by circuitry intrinsic to DD itself. DL and DD both contain recurrent putatively excitatory (glutamatergic) connections as well as local putatively inhibitory (GABAergic) interneurons. In contrast, recurrent excitatory connections appears to be absent in DC, and local inhibition is also barely present. Finally, we speculate on the implications of this pattern of connectivity for theories of short‐term memory and long‐term associative memory. J. Comp. Neurol. 520:3333–3358, 2012. © 2012 Wiley Periodicals, Inc.
The upstream boundary condition influences the leaflet opening dynamics in the numerical FSI simulation of an aortic BMHV
Authors: Annerel Sebastiaan , Degroote Joris , Claessens Tom , Segers Patrick , Verdonck Pascal , Vierendeels Jan 
Published: March 2012

SUMMARYIn this paper, the influence of the upstream boundary condition in the numerical simulation of an aortic bileaflet mechanical heart valve (BMHV) is studied. Three three‐dimensional cases with different upstream boundary conditions are compared. The first case consists of a rigid straight tube with a velocity profile at its inlet. In the second case, the upstream geometry is a contracting left ventricle (LV), positioned symmetrically with respect to the valve. In the last case, the LV is positioned asymmetrical with respect to the valve. The cases are used to simulate the same three‐dimensional BMHV. The change in time of the LV volume is calculated such that the flow rate through the valve is identical in each case. The opening dynamics of the BMHV are modelled using fluid–structure interaction. The simulations show that differences occur in the leaflet movement of the three cases. In particular, with the asymmetric LV, one of the leaflets impacts the blocking mechanism at its open position with a 34% higher velocity than when using the velocity profile, and with an 88% higher velocity than in the symmetric LV case. Therefore, when simulating such an impact, the upstream boundary condition needs to be chosen carefully. Copyright © 2012 John Wiley & Sons, Ltd.
Depolymerization and Hydrodeoxygenation of Switchgrass Lignin with Formic Acid
Authors: Xu Weiyin , Miller Stephen J. , Agrawal Pradeep K. , Jones Christopher W. 
Published: March 2012

AbstractOrganosolv switchgrass lignin is depolymerized and hydrodeoxygenated with a formic acid hydrogen source, 20 wt % Pt/C catalyst, and ethanol solvent. The combination of formic acid and Pt/C is found to promote production of higher fractions of lower molecular weight compounds in the liquid products. After 4 h of reaction, all of the switchgrass lignin is solubilized and 21 wt % of the biomass is shown to be converted into seven prominent molecular species that are identified and quantified. Reaction time is shown to be an important variable in affecting changes in product distributions and bulk liquid product properties. At 20 h of reaction, the lignin is significantly depolymerized to form liquid products with a 76 % reduction in the weighted average molecular weight. Elemental analysis also shows that the resultant liquid products have a 50 % reduction in O/C and 10 % increase in H/C molar ratios compared to the switchgrass lignin after 20 h.
Horseshoe chaos and subharmonic orbits in the nanoelectromechanical Casimir nonlinear oscillator
Authors: Bonnin Michele 
Published: March 2012

SUMMARYThe progressive miniaturization of electronic components today makes feasible to exploit the nanoscale level. At this scale, phenomena peculiar of the quantum world arise, which can be exploited to realize innovative and potential breakthrough devices. In this paper, the dynamic behavior of one such device, the Casimir nonlinear oscillator is analyzed. Using the Melnikov's method, we prove that under the effect of a weak damping and a weak periodic forcing, complex behaviors in the form of Smale's horseshoes arise, and the mechanism leading to their birth is revealed. Copyright © 2012 John Wiley & Sons, Ltd.
Power durability dependence on temperature, input power, and structure of electrodes in SAW filters
Authors: Takayama Ryoichi , Nakanishi Hidekazu 
Published: March 2012

AbstractThe dependence of power durability on temperature and input power has been studied in detail by using SAW filters with AlMgCu/Ti/AlMgCu/Ti four‐layered electrodes. In SAW filters, acceleration factors of degradation are temperature and input power. These two factors are not independent in actual SAW filters, but it is necessary to control the conditions to keep the independence of these two factors in accelerated deterioration tests. As the results of power durability estimation of four‐layered electrodes taking account of the above point, the activation energy of diffusion showed the value of the bulk diffusion level in tests using 800‐MHz‐band filters, and the dependence of the input power increased in proportion to the frequency of the input power. We also successfully improved the power durability of four‐layered electrodes by modifying the layered structure and increasing the Mg content of the AlMgCu alloy layers. In the former case, the dependence on input power did not change but the absolute level versus the input power was improved. In the latter case the dependence on input power and the absolute level versus the input power did not change but the dependence on temperature increased. © 2012 Wiley Periodicals, Inc. Electron Comm Jpn, 95(4): 33‐40, 2012; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ecj.10413
Delta‐tocotrienol suppresses Notch‐1 pathway by upregulating miR‐34a in nonsmall cell lung cancer cells
Authors: Ji Xiangming , Wang Zhiwei , Geamanu Andreea , Goja Arvind , Sarkar Fazlul H , Gupta Smiti V. 
Published: March 2012

AbstractMicroRNAs (miRNAs) are small noncoding RNAs that play critical roles in regulating various cellular functions by transcriptional silencing. miRNAs can function as either oncogenes or tumor suppressors (oncomirs), depending on cancer types. In our study, using miRNA microarray, we observed that downregulation of the Notch‐1 pathway, by delta‐tocotrienol, correlated with upregulation of miR‐34a, in nonsmall cell lung cancer cells (NSCLC). Moreover, re‐expression of miR‐34a by transfection in NSCLC cells resulted in inhibition of cell growth and invasiveness, induction of apoptosis and enhanced p53 activity. Furthermore, cellular mechanism studies revealed that induction of miR‐34a decreased the expression of Notch‐1 and its downstream targets including Hes‐1, Cyclin D1, Survivin and Bcl‐2. Our findings suggest that delta‐tocotrienol is a nontoxic activator of mir‐34a which can inhibit NSCLC cell proliferation, induce apoptosis and inhibit invasion, and thus offering a potential starting point for the design of novel anticancer agents.