Structural origin of coiling in coiled carbon nanotubes

The statistical distribution of a large number of helically coiled carbon nanotubes was analyzed in a cross-correlated way in their geometrical configuration space defined by diameter and pitch. Stability islands were identified, in which the number of coils exceeds about 15-10 times the value corresponding to a uniform distribution. When comparing our data with data from literature, a good agreement is found. The statistical findings are interpreted as indirect evidence that the geometric configuration of coiled carbon nanotubes is rather decided by the atomic structure of carbon layers building up the coils than by the external parameters which on the other hand may induce the particular conditions under which coiling occurs. The possible effect of impurities like N and S on the incorporation of non-hexagonal rings and tubular growth is pointed out.     

The catalytic nanodiode. Its role in catalytic reaction mechanisms in a historical perspective

Catalytic nanodiodes, Pt/TiO₂ or Pt/GaN produce continuous flow of hot electron current during carbon monoxide oxidation for hours in the 80–150 °C temperature range at pressures of 100 Torr of O₂ and 40 Torr of CO. These observations provide proof of the Schottky diode model of oxide supported metal catalysis of many reactions that have been proposed by Schwab, Solymosi and others since the 1960s. The flow of hot electrons should influence chemistry at oxide–metal interfaces and the metal particle size dependence of catalytic activity and selectivity.     

Modifications of and special operating tricks in the classical technique of surgery against strabismus

Even nowadays the idea of most of the operations against strabismus is based on myectomy and reposition of the rectus muscles. At the Department of Ophthalmology of the University Medical School of Debrecen we use mainly these two methods of operation. At our Department we performed 1605 operations against strabismus during the last 10 years. 1269 of our patients had convergent, 336 had divergent strabismus. The majority of the operations were performed on patients less than 6 years of age, under general anesthesia. The outcome of the operation is successful if it results in a situation, in which torque affecting the eyeball stabilizes it in the normal position. The advantage of the combined surgical procedure is that the former muscular balance remains intact, and by relatively small intervention good results can be achieved. In the rectus muscles of squint patients anatomical and histopathological changes could be found, especially if they did not receive pleoptic treatment preoperatively. Depending on the direction of the strabismus one of the muscles is thicker, while the other is thinner, due to hyper- and hypofunction. Our surgical experience of many years showed that by modifying the classical technique of the operations with some fine technical tricks it was possible to increase the success rate. In our film we presented the right way of incising and handling the subconjunctival connective tissue (Tenon capsule) thus making it possible to lay it back to its original place at the end of the operation. This way the chance of postoperative scarring is reduced. We demonstrated how to test the contractility of the muscles by using muscle-hooks, that replaces the forceps test. In case of myectomy we demonstrated the tricks of how to handle the easiest and the finest way. In case of retroposition we can achieve perfect reconstruction and wound healing by using the shown simple technique. We also take much care of suturing the conjunctiva during operations performed on infants that is important because of their undisciplined behavior.     

Reservoir engineering assessment of low-temperature geothermal resources in the Skierniewice municipality (Poland)

Low temperature geothermal resources and their production potential in the Skierniewice area of Poland were evaluated assuming conventional well doublet arrays. The reservoir engineering assessment was carried out, within the framework of a World Bank project, to study the feasibility of providing heat to the local district heating system, using data from two existing wells and from geophysical surveys, and by evaluating results of production, injection and interference well tests. Two options were simulated mathematically, using both semianalytical and numerical codes, considering a simplified reservoir model: one based on the two existing wells, the other considering four wells, two to be drilled. The injection of spent brines into a different reservoir was also studied.     

Personal RF exposimetry in urban area

The purpose of the current study was to evaluate the usefulness of a radiofrequency (RF) personal exposimeter (dosimeter) for assessing individual RF exposure in an urban environment. Measurements taken by RF personal dosimeter were also compared to preliminary site measurements taken around mobile base stations. The results from personal exposure showed that one third of the participants spent 40–70% of 24 h recording time above the detection limits (0.05 V/m), and half of subjects spent less than 10%. The highest exposure was detected during the traveling period and the lowest in bed at home. Based on our results, we concluded that site measurements cannot be used to accurately determine personal exposure. We also concluded that duration of time exposed to RF levels above the detection limit of the personal dosimeter is a useful exposure metric to compare and contrast individual RF exposure of study subjects.     

Über den Pyridingehalt des Tabaks

European Food Research and Technology - In unseren Versuchstabaken (Ungarische Tabake und Trafikfabrikaten) konnten wir Pyridin bzw. Pyridinbasen überhaupt nicht oder nur in Spuren...     

Optical gain in 1.3-μm electrically driven dilute nitride VCSOAs

We report the observation of room-temperature optical gain at 1.3 μm in electrically driven dilute nitride vertical cavity semiconductor optical amplifiers. The gain is calculated with respect to injected power for samples with and without a confinement aperture. At lower injected powers, a gain of almost 10 dB is observed in both samples. At injection powers over 5 nW, the gain is observed to decrease. For nearly all investigated power levels, the sample with confinement aperture gives slightly higher gain.     

New breeding gain definitions and their application to the optimization of a molten salt reactor design

The molten salt reactor (MSR) is an attractive breeder reactor. A graphite-moderated MSR can reach breeding because of the online salt processing and refueling. These features give difficulties when the breeding gain (BG) of the MSR is evaluated. The inventory of the core and external stockpiles have to be treated separately in order to quantify the breeding performance of the reactor. In this paper, an improved BG definition is given and it is compared with definitions used earlier. The improved definition was used in an optimization study of the graphite – salt lattice of the core. The aim of the optimization is a passively safe, self-breeder reactor. The fuel channel diameter, graphite volume and thorium concentration were varied while the temperature feedback coefficient of the core, BG – as defined in the paper – and the lifetime of the graphite were calculated. There is a small range of lattices which provide both negative temperature feedback and breeding. Furthermore, breeding is possible only at low power densities in case of the salt processing efficiencies set in this study. In this range of power the lifetime of the graphite is between 12 and 20 years.     

Parameter Sweep Workflows for Modelling Carbohydrate Recognition

Carbohydrate recognition is a phenomenon critical to a number of biological functions in humans. Understanding the dynamic behaviour of oligosaccharides should help in the discovery of the mechanisms which lead to specific and selective recognition of carbohydrates by proteins. Computer programs which can provide insight into such biological recognition processes have significant potential to contribute to biomedical research if the results of the simulation can prove consistent with the outcome of conventional wet laboratory experiments. In order to validate these simulation tools and support their wider uptake by the bio-scientist research community, high-level easy to use integrated environments are required to run massively parallel simulation workflows. This paper describes how the ProSim Science Gateway, based on the WS-PGRADE Grid portal, has been created to execute and visualise the results of complex parameter sweep workflows for modelling carbohydrate recognition.     

Hybrid MCM-41 grafted by a general microwave-assisted procedure: a characterization study

Hybrid materials obtained through a Microwave-assisted grafting of organic functional groups on mesoporous silica (MCM-41 type) have been characterized by X-ray powder diffraction, TG-DSC, N₂ adsorption, solid state ¹³C- and ²⁹Si-NMR, TEM and SEM. The studied grafting procedure is effective in the preparation of hybrid organosilicas under solvent-free conditions. Microwaves allows an ultra-fast and clean functionalization of the mesoporous materials and the method has been applied to produce a wide series of functional materials. The hybrid materials maintain the original mesoporous structure when the loading of linked organic groups does not exceed 10 %. In this cases, the slight pore volume reduction is linearly correlated to the organic amount in the product. If functional groups able to interact among them through hydrogen bond are used, hybrid materials exhibit high Organic/SiO₂ ratios and low pore volumes due to the formation of a network occluding the pores, where functional groups of free organosilane molecules interacts with the functional groups of molecules linked to the matrix. NMR data confirm that the network is composed by organosilane molecules linked or not to the framework. Acid washing is able to labilize hydrogen bond and open the network. In the case of bulky but chemically inert functionalising agents the network is not produced.