Visualizing the topography of coating surfaces

An optical system for imaging the topography of (coating) surfaces using a video monitor is described. The grey level of the image correlates with the slope of the surface. The principle of operation of the method is explained and some applications are indicated.     

Advanced Monte Carlo simulations of the adsorption of chiral alcohols in a homochiral metal‐organic framework

Grand canonical Monte Carlo (GCMC) simulations with configurational biasing were used to study the enantioselective adsorption of four alkanols in a homochiral metal‐organic framework, known as hybrid organic‐inorganic zeolite analogue HOIZA‐1. Conventional GCMC simulations are not able to converge satisfactorily for this system due to the tight fit of the chiral alcohols in the narrow pores. However, parallel tempering and parallel mole‐fraction GCMC simulations overcome this problem. The simulations show that the enantioselective adsorption of the different (R,S)‐alkanols is due to the specific geometry of the chiral molecules relative to the pore size and shape. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2324–2334, 2014     

56—THE CONTACTLESS MEASUREMENT OF YARN SPEED WITH A LASER–DOPPLER VELOCITY METER

A laser–Doppler velocity-meter system can be used for contactless measurement of the velocity of any optically accessible object scattering light. A relatively simple set-up appears to be suitable for yarn-speed measurements. This system may be useful if contact methods are not possible or if contact methods influence the measurement, e.g., in measurements on yarns directly behind the spinneret, on hot plates and draw pins, and at very high speeds. The accuracy of the measurements depends on several circumstances, such as the optical properties of the yarn, the thickness of the yarn, and the measuring distance. In most cases, an accuracy of about ±2% is attainable. With the system described in this paper, yarn speeds of up to 3000 m/min have been measured with the accuracy mentioned above; the measurement of higher yarn speeds is possible.     

Ontology-based photo annotation

While technology enables the storage and distribution of photographic images on an unprecedented scale, finding what you want can be like finding the proverbial needle in a haystack. The authors describe their approach and the tool they developed to make annotating photos and searching for specific images more intelligent.     

On the application of chiral amplification via adsorption

Chiral amplification is a known phenomenon in crystallization. Recent atomistic simulations have shown that amplification can also occur in equilibrium processes when a mixtures of chiral molecules adsorb in metal-substituted zeolites that are not chiral by themselves. In this article we investigate how this process could be exploited for enantiopurification and separation in a pressure-swing adsorption process. For this purpose, we develop a mathematical model that reproduces the main features of the full-atom simulations and allows us to study the impact of several parameters on the enantioselectivity on a macroscopic scale. Besides numerical solutions of this model, we provide some analytic results which suggests that the enantioselective materials prohibit a phase transition as a function of temperature. Below a certain critical temperature, the enantiomeric content of the adsorbed phase becomes a discontinuous function of the enantiomeric gas content. This has the following consequences: (i) the adsorbed phase in racemic conditions becomes unstable, (ii) a sudden increase in efficiency of the purification process, and (iii) the possibility to not only purify but also fully separate chiral mixtures using a parallel batch process in which both lines use an input that is enriched with opposite enantiomer.     

Negative Thermal Expansion Design Strategies in a Diverse Series of Metal–Organic Frameworks

Negative thermal expansion materials are of interest for an array of composite material applications whereby they can compensate for the behavior of a positive thermal expansion matrix. In this work, various design strategies for systematically tuning the coefficient of thermal expansion in a diverse series of metal–organic frameworks (MOFs) are demonstrated. By independently varying the metal, ligand, topology, and guest environment of representative MOFs, a range of negative and positive thermal expansion behaviors are experimentally achieved. Insights into the origin of these behaviors are obtained through an analysis of synchrotron‐radiation total scattering and diffraction experiments, as well as complementary molecular simulations. The implications of these findings on the prospects for MOFs as an emergent negative thermal expansion material class are also discussed.     

Prevalence of blindness and visual impairment in the region of Ségou, Mali. A baseline survey for a primary eye care programme

A community-based cross-sectional study on the prevalence and causes of blindness and visual impairment was conducted between July and August 1990 in three rural districts in Ségou region, Mali. The study population consisted of 5871 villagers. In the study area, the overall prevalence of bilateral blindness was 1.7% (standardized rate for age 2.0% +/- 0.4%), of bilateral visual impairment 1.7% (2.1% +/- 0.4%), of unilateral blindness 1.7% (2.2% +/- 0.4%) and of unilateral visual impairment 1.0% (1.2 +/- 0.3%). No important differences were found between districts. Cataract was the most common cause of visual loss (54%) and was most prevalent among those over 50 years of age. In 43%, unilateral blindness was associated with trauma. Other major eye diseases accounting for high percentages of visual impairment were trachoma and glaucoma. Xerophthalmia appeared to be a major public health problem among children in the age group 0-5. It was concluded that blindness is a major public health problem in this region. Some recommendations are given for strengthening integrated primary eye care at the district level in Ségou region.