Chemical vapor deposition synthesis of self-aligned carbon nanotube arrays

A procedure for producing arrays of self-aligned carbon nanotubes (CNTs) using standard chemical vapor deposition (CVD) is reported. Using UV photolithography, silicon substrates are patterned with a thin layer of thermally evaporated iron as a CNT catalyst. The CVD synthesis was carried out over a small temperature range (700°C–800°C) using acetylene and methane gasses, producing aligned CNT towers. Scanning electron microscopy (SEM) analysis shows a relationship between CNT tower height and synthesis time. Additionally, results show that impurity particles dramatically effect CNT tower growth. These results indicate that aligned CNTs can be produced in a desired pattern with height control.     

Enhanced Simulated Annealing Technique for the Single-Row Routing Problem

This paper presents ESSR (Enhanced Simulated annealing for Single-row Routing) model for solving the single-row routing problem. The main objective in this problem is to produce a realization that minimizes both the street congestion and the number of doglegs. Simulated annealing (SA) is a stochastic, hill-climbing and gradient-descent technique based on the statistical properties of particles undergoing thermal annealing. By performing slow cooling, the nets in the single-row routing problem align themselves according to a configuration with the lowest energy. The model has been known to produce reasonably good solutions for many NP-complete optimization problems, such as the single-row routing problem. In ESSR, our strategy is to minimize both the street congestion and the number of interstreet crossings (doglegs) by expressing a single energy function as their collective properties. This objective is achieved by representing the energy as the absolute sum of the heights of the net segments. To speed up convergence, we pivot the street congestion value while having the energy drops directly proportional to the number of doglegs. This action has the effect of minimizing the number of doglegs as the energy stabilizes. Our simulation work on ESSR produces optimal results in most cases for both the street congestion and the number of doglegs. Our experimental results compare well against results obtained from our earlier model (SRR-7) and two other methods reported in the literature.     

An automated gantry crane as a large workspace robot

In the context of further automation of manufacturing processes, automated transportation of heavy weights using cranes becomes more and more important. Applying the skills of robots to crane automation, a wide market of new applications could be developed. The main idea is to interpret the crane as a large workspace-serving robot. The crane hook represents the effector of the robot. As an example for the effector, an automated storage and retrieval unit for rack operations by a crane with three active auxiliary effector axes has been developed and integrated into the control concept. The control has been realized for a reconstructed 5-t-bridge crane with workspace dimensions of 30 m×8.7 m×7 m.     

A syndrome of molybdenosis, copper deficiency, and type 2 diabetes in the moose population of south-west Sweden

Since the mid-1980s, a 'mysterious' disease has been afflicting the moose (Alces alces L.) population of south-western Sweden. Molybdenosis combined with secondary copper deficiency syndrome has been suggested as the cause of the clinical signs and of necropsy findings, supported by trace element analysis. Copper deficiency has long been associated with disturbed carbohydrate metabolism and also with oxidative stress. When testing the oxidative stress hypothesis, we found increased concentrations of the glycoxidation products pentosidine and carboxymethyl-lysine (CML), both in plasma proteins and in renal tissue, when compared with control values. The concentration of glycated lysine (furosine), a marker of hyperglycaemia, was also increased. These data, together with elevated insulin levels in affected moose, strongly suggest that they are suffering from an environmentally-induced, non-insulin-dependent type 2 diabetes.     

Two-beam cross-correlation: a method to characterize transport phenomena in micrometer-sized structures

To determine flow properties, namely, the velocity and angle of the flow in microstructured channels, an experimental realization based on fluorescence correlation spectroscopy is described. For this purpose, two micrometer-sized spatially separated volume elements have been created. The cross-correlation signal from these has been recorded and evaluated mathematically. In addition to previous results, two-beam cross-correlation allows for fast and easy determination of even small (down to 200 μm/s) flow velocities, as well as simultaneous measurement of diffusion properties of single dye molecules within a rather short detection time of 5-100 s and an error rate of less than 20%. The spatial flow resolution is around 1-2 μm, limited by the diameter of the volume element. Furthermore, vectorial flow data can be obtained and evaluated. A discussion of the theoretical background and an experimental verification of the theoretical results is performed. The feasibility of fast and easy data processing is shown if the flow time is the only desired information. Possible applications of this precise and simple method are the determination of transportation effects within artificial microstructures for CE and HPLC, fast chemical kinetics, and high-throughput screening.     

Secretarial attitudes towards word processors as a function of familiarity and locus of control

The purpose of the present study was to investigate dimensions of secretarial anxiety, eagerness, and curiosity with respect to word processing equipment. Such variables as familiarity, formal training, physical proximity to the equipment, degree of influence in the decision to acquire a word processor, and frequency of use were seen as potential predictors of such attitudes. Additionally, two trait-like dimensions were measured, locus of control and complexity. Questionnaires were sent to 408 secretaries employed at a mid-western university. The response rate was 59 per cent (n = 241). People who had not used word processing equipment were more anxious than those individuals who had. Moreover, frequency of use for people with experience was related to greater change in anxiety levels. While familiarity reduced anxiety, it also tended to reduce curiosity. Frequency of word processor use was related to several variables. For instance, frequency of use was related to how positively the person evaluated the processor as affecting their work capabilities. Heavy users felt that the manuals were less helpful. Internally controlled individuals were more eager, curious and less anxious, while cognitively complex individuals were more curious about word processors. The applied implications of the findings are discussed.     

Identification of the Sex Pheromone of the Currant Shoot Borer Lampronia capitella

Under an artificial light:dark cycle, females of Lampronia capitella were observed calling, with extended terminal abdominal segments, during the first 2 hr of the photoperiod. Extracts of terminal abdominal segments from females elicited large electroantennographic responses from male antennae. Gas chromatography with electroantennographic detection revealed three active peaks. Based on comparison of retention times and mass spectra of synthetic standards, these compounds were identified as (Z,Z)-9,11-tetradecadienol and the corresponding acetate and aldehyde. The electroantennographic activity of the four geometric isomers of all three compounds was investigated, and the respective (Z,Z)-isomer was found to be the most active in all cases. Aldehydes generally elicited larger antennal responses than alcohols, whereas acetates were the least active compounds. A subtractive trapping assay in the field, based on a 13:26:100 micrograms mixture of (Z,Z)-9,11-tetradecadienal, (Z,Z)-9,11-tetradecadienyl acetate, and (Z,Z)-9,11-tetradecadienol confirmed that all three compounds are pheromone components. Subtraction of (Z,Z)-9,11-tetradecadienol from the blend completely eliminated its attractiveness, whereas the other two-component blends showed reduced activity. This is the first pheromone identification from the monotrysian superfamily Incurvarioidea, confirming that the common pheromones among ditrysian moths (long-chain fatty acid derivatives comprising alcohols, acetates, and aldehydes with one or more double bonds) is not an autapomorphy of Ditrysia, but a synapomorphy of the more advanced heteroneuran lineages.     

Impact of natural organic matter (NOM) on freshwater amphipods

Natural organic matter (NOM) isolated from the eutrophic Sanctuary Pond (Point Pelee National Park, Canada) has an adverse impact on amphipod species (Gammarus tigrinus and Chaetogammarus ischnus from Lake Müggelsee, Germany, and Eulimnogammarus cyaneus, from Lake Baikal, Russia). Increases in amphipod mortality, changes in peroxidase activity and increases of heat shock protein (hsp70) expression were observed upon exposure to NOM. The highest resistance to the adverse impact of NOM was observed with the endemic Baikalian amphipod E. cyaneus. However, the mechanisms behind this finding remains obscure. If differences in the sensitivity of the hsp70 antibody may be excluded, different modes of action may be postulated: because the adverse impact of NOM may be caused by reactive oxygen species (ROS) and the NOM itself, the observed differences may be due to the action of ROS alone (with E. cyaneus) and a combination of both adverse modes of action (European species).     

The influence of a back support harness on spinal forces during sheep shearing

Previous research has classified the occupation of sheep shearing as heavy work where shearers flex their spine and hips for long periods of time, handle awkward loads and expend high amounts of energy. The aim of this research was to investigate the magnitude of spinal forces produced during the shearing phase of the work and to determine whether the use of a commercially available back support harness would reduce these forces. Following discussion on task complexity and risk of back injury with senior shearing instructors, three component tasks of the shearing phase were identified as posing high risk of injury and were prioritized for primary analysis. Although the dragging out of a sheep in preparation for shearing and an unexpected loss of animal control were also identified as being of high risk, technological and instrumentation difficulties precluded their analysis. Twelve experienced shearers were videotaped while shearing with and without the use of a back harness. Surface mounted retro-reflective markers placed on the trunk defined three linked segments: Pelvis, Lumbar and Head, Arms, and Upper Trunk (HAUT). A 3D, link segment, top down, inverse dynamics approach was used to describe the motion and to estimate forces involved during the identified tasks of shearing. The spinal force/time profiles of this sample of shearers demonstrated large compressive and shear forces for all three tasks that are close to the NIOSH and University of Waterloo action limits for compressive and shear forces respectively (McGill 1997, Yingling and McGill 1999, Marras 2000). The use of the back support harness reduced these forces by substantial and statistically significant amounts. This effect was consistent across all three tasks. The results of this study demonstrate the production of high levels of compressive and shear forces within the spine of shearers during the three shearing tasks studied and that the use of a back support harness can substantially reduce these forces. Therefore the use of a back harness may reduce the cumulative load on the spine during shearing thereby moderating damage to the articular structures. However it is not known whether the harness would protect the spine from a sudden or unexpected force.