Stopping power and ranges of electrons, protons and alpha particles in liquid water using the Geant4-DNA package

This paper presents stopping power and ranges of electrons, protons, and alpha particles in liquid water, calculated using the latest Geant4-DNA processes implemented in the Geant4 Monte Carlo simulation toolkit. Inelastic cross sections are obtained using the first Born approximation and semi-empirical formulas like Rudd’s model for ionisation and the Miller and Green formula for excitation. Elastic collisions and vibrational excitations are considered for tracking electrons until complete thermalisation (0.025 eV). A speed scaling procedure with an effective charge screening term was used to compute alpha particle and heavy ion cross sections. Geant4-DNA simulations were carried out using thin liquid water volumes to determine the linear energy loss (dE/dX), while larger volumes were used to obtain the particle range. While results converge for highly energetic particles, differences are observed for low energies when the applied theoretical models begin to diverge from each other. Results show a good agreement between the analytical calculations obtained from the models, the Geant4-DNA Monte Carlo simulation predictions and the data published in the ICRU reports. Geant4-DNA processes apply to the following energy ranges: 0.025 eV-1 MeV for electrons, 100 eV-100 MeV for protons and 1 keV-400 MeV for alpha particles in liquid water, however since experimental data for very low energies is scarce and very difficult to obtain these processes could not be thoroughly validated so they are recommended for energies above 1 eV for electrons, 1 keV for protons and 10 keV for alpha particles. Relativistic, highly charged ions were implemented in our own “house” version of the code and will be available in future releases of Geant4.     

Precise Extraction of Charge Carrier Mobility for Organic Transistors

Unreliable mobility values, and particularly greatly overestimated values and severely distorted temperature dependences, have recently hampered the development of the organic transistor field. Given that organic field‐effect transistors (OFETs) have been routinely used to evaluate mobility, precise parameter extraction using the electrical properties of OFETs is thus of primary importance. This review examines the origins of the various mobilities that must be determined for OFET applications, the relevant extraction methods, and the data selection limitations, which help in avoiding conceptual errors during mobility extraction. For increased precision, the review also discusses device fabrication considerations, calibration of both the specific gate‐dielectric capacitance and the threshold voltage, the contact effects, and the bias and temperature dependences, which must actually be handled with great care but have mostly been overlooked to date. This review serves as a systematic overview of the OFET mobility extraction process to ensure high precision and will also aid in improving future research.     

Sustainable control strategies for plant protection and food packaging sectors by natural substances and novel nanotechnological approaches

An overview is provided of the current technological strategies (also at the nanoscale level) recently involved in plant and/or food protection. In addition, the potential use of natural and sustainable substances, instead of traditional synthesized molecules or chemical-based compounds, is addressed both with respect to packaging systems and novel pesticide formulations. In this context, nanotechnological approaches represent promising strategies for the entire agriculture industry chain, from the field to consumers. Traditional plant protection strategies are often insufficient and the application of chemical-based pesticides has negative effects on animals, humans and the environment. Novel greener tools could represent efficient alternatives for the management of plant diseases using promising strategies; the use of nanotechnologies allows the promotion of the more efficient assembly and subsequent release of environmentally sustainable active principles, limiting the use of chemicals in terms of economic losses. At the same time, new sustainable, antimicrobial and antioxidant systems have been rapidly promoted and investigated in the food packaging sector as a valid eco-friendly possibility for improving the safety and quality of food products and reducing and/or limiting the environmental impact with respect to traditional materials. Together, the scientific community and the growing interest of consumers have promoted the development of new edible and eco-friendly packaging that reduces waste and any environmental impact. In this context, the aim is to provide evidence of the usefulness of strategies aiming to limit agrochemicals, as well as the potential of nanomaterials, in sustainable plant and food protection for agriculture management and the packaging sector. © 2018 Society of Chemical Industry     

Stability of aflatoxin M in milk.

This three-part study was designed to determine aflatoxin M recovery from pasteurized and/or stored cow's milk. (a) Aflatoxin M was added to samples of raw Holstein milk at a concentration of 2.0 mug/liter. Half of each sample then was pasteurized at 63 C for 30 min, and both raw and pasteurized portions were stored at 4 C up to 17 days. (b) Samples of raw milk, pasteurized (77 C, 16 s) skim milk, dry cottage cheese curd, and cottage cheese whey were taken from a commercial operation in an area in which natural contamination had been encountered. (c) Milk from a cow dosed with aflatoxin B1 was stored frozen (-18 C) in bulk and in assay-size sample containers for 120 days. Aflatoxin M was recovered completely after either storage or pasteurization in (a) and (b). In (c), a recovery deficiency was detectable after 68 days of storage, which increased to 45% of the original value by 120 days. These observations differ from those of others in that loss of aflatoxin M was significant after pasteurization or storage of raw milk, totaling 87% loss after 120 days of frozen storage. Aflatoxin M partitioning between curd and whey in the preparation of cottage cheese agrees with more recent studies, but differs from previous reports. Three possible explanations for the differences are offered.     

Robust stability analysis of structures with uncertain parameters using mathematical programming approach

This paper presents a novel mathematical programming approach for the static stability analysis of structures with uncertainties within the framework of FEM. The considered uncertain parameters are material properties, geometry of element cross section, and loading conditions, all of which are described by an interval model. The proposed method formulates the two cases of interest, namely, worst and best buckling load calculation, into a pair of mathematical programming problems. Two straightforward advantages are exhibited by such formulations. The first advantage is that the proposed formulation can overcome the interference on the sharpness of bounds of the buckling load due to the interval dependence issue. The second benefit is that the information of uncertain parameters causing the extremities of buckling load can always be retrieved as by‐products of the uncertain stability analysis. Some numerical examples are presented to illustrate the capability of the proposed method on various structures and the sharpness of the bounds of the buckling load factors. The efficiency and effectiveness of the proposed method are also demonstrated through comparison with the classical Monte Carlo simulation method. Copyright © 2014 John Wiley & Sons, Ltd.     

Polymer‐Based Stimuli‐Responsive Recyclable Catalytic Systems for Organic Synthesis

The introduction of stimuli‐responsive polymers into the study of organic catalysis leads to the generation of a new kind of polymer‐based stimuli‐responsive recyclable catalytic system. Owing to their reversible switching properties in response to external stimuli, these systems are capable of improving the mass transports of reactants/products in aqueous solution, modulating the chemical reaction rates, and switching the catalytic process on and off. Furthermore, their stimuli‐responsive properties facilitate the separation and recovery of the active catalysts from the reaction mixtures. As a fascinating approach of the controllable catalysis, these stimuli‐responsive catalytic systems including thermoresponsive, pH‐responsive, chemo‐mechano‐chemical, ionic strength‐responsive, and dual‐responsive, are reviewed in terms of their nanoreactors and mechanisms.     

Early identification of reading difficulties using heterogeneous developmental trajectories.

Serious conceptual and procedural problems associated with current diagnostic methods call for alternative approaches to assessing and diagnosing students with reading problems. This study presents a new analytic model to improve the classification and prediction of children's reading development. Growth mixture modeling was used to identify the presence of 10 different heterogeneous developmental patterns. In all, 411 children in kindergarten through Grade 2 from 3 elementary schools in Texas were administered measures of phonological awareness, word recognition, and rapid naming skills 4 times a year. The mean ages were 5.8 years (SD = 0.35) for the kindergartners, 6.9 years (SD = 0.39) for Grade 1, and 8.0 years (SD = 0.43) for Grade 2; the percentage of boys was 50%. The results indicate that precursor reading skills such as phonological awareness and rapid naming are highly predictive of word reading (word recognition) and that developmental profiles formed in kindergarten are directly associated with development in Grades 1 and 2. Students identified as having reading-related difficulties in kindergarten exhibited slower development of word recognition skills in subsequent years of the study. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differences in receptor binding of LDL subfractions

Differences in low density lipoprotein (LDL) receptor-binding affinity among LDL particles of different size were examined in competitive binding assays in human skin fibroblasts and LDL (d = 1.020 to 1.050 g/mL) from subjects with a predominance of large (> or = 272 A), medium (259 to 271 A), and small (< or = 257 A) LDL. Among 57 normolipidemic subjects with LDL cholesterol (-C) levels < 160 mg/dL, binding affinity was reduced by 16% in those with predominantly large LDL and by 14% in those with small LDL compared with most subjects who had a predominance of medium-size LDL and in all LDL size subgroups in 66 subjects with LDL-C > or = 160 mg/dL. Differences in LDL receptor-binding affinity were further investigated by using LDL density subfractions (I, d = 1.026 to 1.032 g/mL; II, d = 1.032 to 1.038 g/mL; and III, d = 1.038 to 1.050 g/mL) from three subjects with predominantly large (pattern A) and small (pattern B) LDL particles. The binding affinity (Kd) of LDL-II was similar for patterns A and B (9.2 +/- 1.4 and 9.4 +/- 0.7, respectively) and 30% lower in LDL-III from both groups (P < .05). The binding affinity of LDL-I in pattern A (12.6 +/- 1.5 micrograms/mg) was lower (P < .05) than that in LDL-II and LDL-I from pattern B (8.0 +/- 2.4 micrograms/mg). After incubation with a monoclonal antibody that specifically blocked the LDL receptor-binding domain of apoE, LDL-I from two pattern B subjects showed substantially lower binding affinity (Kd = 20.0 and 19.2 micrograms/mg) than in pattern A (Kd = 13.2 and 14.2 micrograms/mg), a result consistent with our finding of a higher apoE content in pattern B LDL-I (P < .001). Thus, factors associated with variations in particle size and apoE content in LDL subclasses in normolipidemic subjects contribute to the differences in LDL receptor binding that may result in differing metabolic behavior in vivo.     

A Golgi localization signal identified in the Menkes recombinant protein

Menkes disease arises from a genetic impairment in copper transport. The gene responsible for the phenotype has been identified as a copper transporting ATPase ( ATP7A ). Recently, the protein encoded by the ATP7A gene has been localized to the Golgi complex. In order to investigate the role of the Menkes disease protein in copper transport, recombinant constructs containing both the full-length open reading frame and an alternatively spliced form have been successfully expressed and localized in mammalian cells. Other studies of a patient with occipital horn syndrome, an allelic variant of Menkes disease, have demonstrated that only this alternatively spliced isoform and not the full-length form is expressed in this patient. The milder form of this patient's phenotype suggests that the alternatively spliced isoform has some functional role in copper transport. In the present study the full-length recombinant Menkes protein was shown by immunofluorescence to localize to the Golgi apparatus and the alternatively spliced form, lacking sequences for transmembrane domains 3 and 4 encoded by exon 10, was shown to localize to the endoplasmic reticulum. Using sequences from exon 10 fused to a non-Golgi reporter molecule, a 38 amino acid sequence containing transmembrane domain 3 of the Menkes protein was found to be sufficient for localization to the Golgi complex. Therefore, the protein sequence encoded by exon 10 may be responsible for this differential localization and both isoforms may be required for comprehensive transport of copper within the cell.     

Inhibition of ingestive behavior following fourth ventricle bombesin injection in chronic decerebrate rats.

Tested the hypothesis that the effects of 4th ventricle bombesin (BN) injection on feeding require interaction with forebrain neural systems by measuring intraoral sucrose (0.1 M) in tube-fed control and tube-fed supracollicular decerebrate rats after 4th ventricle injections of 1, 5, 10, 20, and 50 ng BN. Fourth ventricle injections of all doses of BN reliably suppressed sucrose intake in both control and chronic decerebrate rats. These results indicate that caudal brain-stem afferent signals produced by 4th ventricle BN injections are integrated by the local neural circuitry of the caudal brain stem, independent of the forebrain systems, to modulate ingestive behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)