Neutronics optimization and characterization of a long‐life SCO2‐cooled micro modular reactor

This paper presents a neutronics optimization study of a supercritical CO₂‐cooled micro modular reactor (MMR). The MMR is a fast‐spectrum reactor designed to be an extremely compact, integrated, and truck‐transportable reactor with 36.2‐MWth power and a 20‐year lifetime without refueling. The reactor uses a drum‐type primary control system and a single absorber rod located at the core center as the secondary ultimate shutdown system. In order to maximize the fuel inventory in a compact fast reactor, hexagonal fuel assemblies are adopted in this work. We compare two types of MMR: One is using U¹⁵N fuel, and the other one is based on UC fuel. In addition, the minimization of the core excess reactivity to less than 1 dollar is also achieved in this study by a unique application of a replaceable fixed absorber in order to enhance safety of the MMR core by preventing the possibility of a prompt criticality accident. Moreover, the required number of primary control drums is also reduced through minimization of the excess reactivity. Several important safety parameters such as control rod/drum worth, reactivity coefficients, and power peaking factors are also characterized as a function of core burnup. The neutronics analyses and depletion calculations are all performed using the continuous‐energy Monte Carlo Serpent code with the latest evaluated nuclear data file (ENDF/B‐VII.1) library. Copyright © 2016 John Wiley & Sons, Ltd.     

Optical Control of Antibody Activity by Using Photocleavable Bivalent Peptide–DNA Locks

Antibody-based molecular recognition plays a central role in today's life sciences, ranging from immunoassays to molecular imaging and antibody-based therapeutics. Control over antibody activity by using external triggers such as light could further increase the specificity of antibody-based targeting. Here we present bivalent peptide–DNA ligands containing photocleavable linkers as a noncovalent approach by which to allow photoactivation of antibody activity. Light-triggered cleavage of the 3-amino-3-(2-nitrophenyl)propionic acid peptide linker converted the high-affinity bivalent peptide–DNA lock into weakly binding monovalent ligands, effectively restoring antibody targeting of cell-surface receptors. In this work, a proof of principle was provided with an anti-hemagglutinin antibody, but the molecular design of the lock is generic and applicable to any monoclonal antibody for which an epitope or mimotope of sufficient affinity is available.     

His-tags as Zn(II) binding motifs in a protein-based fluorescent sensor

Fluorescent indicators that allow real-time imaging of Zn(II) in living cells are invaluable tools for understanding Zn(II) homeostasis. Genetically encoded sensors based on fluorescence resonance energy transfer between fluorescent protein domains have important advantages over synthetic probes. We discovered that hexahistidine tags have a strong tendency to dimerize upon binding of Zn(II) in solution and we used this principle to develop a new protein-based sensor for Zn(II). Enhanced cyan and yellow fluorescent proteins were connected by long flexible peptide linkers and His-tags were incorporated at both termini of this fusion protein. The resulting sensor CLY9-2His allows the ratiometric fluorescent detection of Zn(II) in the nanomolar range. In addition, CLY9-2His is selective over the physiologically relevant metal ions Fe(II), Mn(II), Ca(II) and Mg(II). Our approach demonstrates the potential of using small peptides as metal-binding ligands in chelating fluorescent protein chimeras.     

PLA/metal oxide biocomposites for antimicrobial packaging application

ABSTRACT

The effects of metal oxide addition in polylactic acid (PLA) film were investigated in this study. PLA/Metal Oxide biocomposites were prepared by solvent casting method. The incorporation of metal oxide resulted in no chemical structure change of neat PLA. PLA/ZnO and PLA/MgO exhibited the widest inhibition while PLA/TiO₂ resulted in the smallest inhibition zone. The addition of metal oxides caused fracture and void on the surface of PLA. The addition of metal oxide into PLA films decreased the tensile strength at the concentration higher than 0.1 per hundred resin (phr). Incorporation of metal oxides accelerated the thermal degradation of PLA and tends to increase the biodegradability of PLA.     

童梦之旅——荷兰伊拉斯谟医疗中心

伊拉斯谟医疗中心位于荷兰鹿特丹市，是名校伊拉斯谟大学的附属医院。它于2007年底完成了全新的室内装修，使用至今，已得到了医院员工和病人的一致好评。他们都将这个充满现代感的医院视为令人愉快的工作场所和舒心的疗养胜地。     

The relationship between cigarette use, nicotine dependence, and craving in laboratory volunteers.

Data from epidemiological studies suggest that individual differences in cigarettes per day (CPD) and duration of smoking account for only a small portion of the variance in Diagnostic and Statistical Manual of Mental Disorders (4th ed.) (DSM-IV) nicotine dependence. However, DSM-IV may be an insensitive measure of nicotine dependence; other measures might better reflect the true nature of the relationship between use and dependence. This paper describes the relationship between cigarettes per day (CPD) and years smoking and the severity of nicotine dependence as measured by the Nicotine Dependence Syndrome Scale (NDSS). Furthermore, we assessed the validity of individual differences in nicotine dependence by determining whether they related to cue-evoked craving during abstinence. Data were pooled from five laboratory studies of 489 regular (i.e., 15+ CPD) smokers. In contrast to previously reported data demonstrating a relatively strong relationship between CPD and dependence in chippers (Shiffman & Sayette, 2005), CPD and years smoking accounted for a statistically significant, but small (<6%), portion of the variance in nicotine dependence in daily smokers. Individual differences in both CPD and years smoking had little or no relationship with craving. However, the magnitude of craving was significantly related to the degree of nicotine dependence even after controlling for use variables and excluding craving-related items on the NDSS. These data suggest that among moderate to heavy daily smokers, meaningful individual differences in nicotine dependence are observed independent of differences in current daily cigarette consumption and duration of smoking. Further research into the sources of this variance is critical to understanding the process of and risk for nicotine dependence.     

Experimental evidence for a causal relationship between smoking lapse and relapse.

In this study, the authors prospectively evaluated the impact of a smoking lapse on relapse probability. After 4 days of smoking abstinence, 60 smokers were randomly assigned to smoke 5 nicotine-containing or 5 denicotinized cigarettes, or to remain abstinent (no lapse) during a 4-hr time period. Afterward, smoking abstinence was encouraged with monetary incentives, and smoking behavior was tracked for 6 days. Relative to the no-lapse condition, exposure to either of the cigarette types more than doubled the probability of subsequent smoking. Smoking outcomes did not differ between nicotine-containing and denicotinized cigarettes. The data suggest that stimulus factors may play an important role in lapse to relapse processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)