Toward Precision Measurement and Manipulation of Single‐Molecule Reactions by a Confined Space

All chemical reactions can be divided into a series of single molecule reactions (SMRs), the elementary steps that involve only isomerization of, dissociation from, and addition to an individual molecule. Analyzing SMRs is of paramount importance to identify the intrinsic molecular mechanism of a complex chemical reaction, which is otherwise implausible to reveal in an ensemble fashion, owing to the significant static and dynamic heterogeneity of real‐world chemical systems. The single‐molecule measurement and manipulation methods developed recently are playing an increasingly irreplaceable role to detect and recognize short‐lived intermediates, visualize their transient existence, and determinate the kinetics and dynamics of single bond breaking and formation. Notably, none of the above SMRs characterizations can be realized without the aid of a confined space. Therefore, this Review aims to highlight the recent progress in the development of confined space enabled single‐molecule sensing, imaging, and tuning methods to study chemical reactions. Future prospects of SMRs research are also included, including a push toward the physical limit on transduction of information to signals and vice versa, transmission and recording of signals, computational modeling and simulation, and rational design of a confined space for precise SMRs.     

Patrick Geddes's (e)utopian Belvedere in Southern France

The Collège des Ecossais in Montpellier, France, Patrick Geddes' last major project and place of death in 1932, may have been a mere reproduction of his Edinburgh Outlook Tower under fairer skies. The site Geddes fell in love with in the South was, characteristically of his ideals, mostly a place with a view, in fact over much of Languedoc. As we shall show, this view was one of a whole region made ‘legible’ at a glance, with city, mountains and sea, a prospect at the same time wide and limited, an area with ready access to the rest of the world yet self-contained. Besides, what the ageing Geddes wanted to achieve near Montpellier was no less than to gather a representative assemblage of up-and-coming scholars from three continents. Yet again, the Collège may have been an excuse for Geddes to postpone the writing of long-awaited books. However, we will see that it also served as a stone-and-mortar receptacle for his ideas and systems, which would hardly be surprising from a thinker who was ever looking for ways of escaping traditional teaching methods.     

Particle swarm optimization for solving engineering problems: A new constraint-handling mechanism

This paper addresses constrained and optimal engineering problems solved using an adapted particle swarm optimization (PSO) algorithm. In fact, a specific constraint-handling mechanism is presented. It consists of a closeness evaluation of the solutions to the feasible region. The total constraints violation is introduced as an objective function to minimize. Interval arithmetic is used to normalize the total violations. The resulting objective problem is solved using a simple lexicographic method. The new algorithm is called CVI-PSO for constraint violation with interval arithmetic PSO. The paper provides numerous experimental results based on a well-known benchmark and comparisons with previously reported results. Finally, a case study of the optimal design of an electrical actuator with several model reformulations is detailed.     

Constructing side chains on near-native main chains for ab initio protein structure prediction

Is there value in constructing side chains while searching proteinconformational space during an ab initio simulation? If so,what is the most computationally efficient method for constructingthese side chains? To answer these questions, four publishedapproaches were used to construct side chain conformations ona range of near-native main chains generated by ab initio proteinstructure prediction methods. The accuracy of these approacheswas compared with a naive approach that selects the most frequentlyobserved rotamer for a given amino acid to construct side chains.An all-atom conditional probability discriminatory functionis useful at selecting conformations with overall low all-atomroot mean square deviation (r.m.s.d.) and the discriminationimproves on sets that are closer to the native conformation.In addition, the naive approach performs as well as more sophisticatedmethods in terms of the percentage of     

Additive diffusion coefficients in polyolefins. II. Effect of swelling and temperature on the D = f(M) correlation

Diffusion coefficients of a large panel of molecules were experimentally measured in virgin polypropylene at 40 and 70°C and in swollen polypropylene at 40°C. The influence of mobility increase brought out by temperature or swelling are compared. The effects are more important for high molecular weight compounds. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2434–2443, 2001     

A pulsed field gradient and NMR imaging investigations of the water retention mechanism by cellulose ethers in mortars

The study presented in this paper is devoted to improve the knowledge on the influence of cellulose ethers (CE) on the freshly-mixed mortars water retention. Indeed, this crucial property is the most important imparted by these polysaccharides. One of the assumptions proposed to explain this phenomenon is that CE acts as diffusion barrier to the water. To test this hypothesis, the CE effect on the self-diffusion coefficient of water in solution and on the water mobility between two fresh cement pastes was studied by Nuclear Magnetic Resonance. CE does not significantly modify the water self-diffusion coefficient in CE solution or in admixed cement pastes. Moreover the interdiffusion imaging experiments demonstrated that the water diffusion at the paste/paste interface is not affected by the presence of cellulosic admixture.     

Rates and predictors of DUI among U.S.–Mexico border and non-border Mexican Americans

This paper examines driving under the influence (DUI) arrests and other related factors among Mexican Americans living in U.S.–Mexico border and non-border areas. Respondents in the non-border areas (primarily Houston and Los Angeles) constitute a multistage probability sample (N = 1288) of these areas, interviewed as part of the 2006 Hispanic Americans Baseline Alcohol Survey (HABLAS). Respondents in the border area (N = 1307) were interviewed between March 2009 and July 2010 and constitute a household probability sample of Mexican Americans living on the border. In both surveys, data were collected during computer assisted interviews conducted in respondents’ homes. The HABLAS and the border sample response rates were 76% and 67%, respectively. Border or non-border residential location was not associated with self-reported DUI, 12 month DUI arrest, or lifetime DUI arrest. An increase in consumption of 5 drinks per week was associated with an 18% increase in the chance of self-reporting DUI and an 18% increase in the probability of a lifetime DUI arrest. Binge drinkers were more likely to self-report a DUI event (OR = 2.85, 95% CI = 1.61–5.03; p < .001) and a lifetime DUI arrest (OR = 2.81; 95% CI = 1.43–5.53, p < .01). Most respondents, independent of residential location, recognized DUI as a major problem affecting Hispanics. However, while most correctly identified the legal blood alcohol content to drive in their state as .08 g/dl or lower, approximately one third of individuals were unaware of the legal limit. Compared to their non-border counterparts, border men were more likely to identify a bar/tavern/club and border women were more likely to identify a friend or relative's home as the places of last drink before the most recent DUI trip originated. In conclusion, border and non-border Mexican Americans are not different regarding DUI rates. These rates are high in both groups, especially among men. Intervention strategies to decrease DUI should be implemented not only in drinking establishments but also with families.