A new technique for specimen manipulation in the scanning electron microscope

By the use of suitable DC micromotors mounted on the specimen stage of the Cambridge Scanning Electron Microscope (SEM), extra degrees of freedom may be imparted to the specimen, thus enabling a more thorough examination of a surface to be carried out. The properties that make an electric motor suitable for use inside the vacuum specimen chamber are discussed. After showing the way in which DC motors have successfully solved two problems in the fibre field, some further applications are proposed.     

Mechanical anisotropy of oriented polymers

Measurements of tensile and shear yield stress have been made on strips cut at various angles to the draw direction from films of drawn amorphous poly(ethylene terephthalate). The data were well fitted by a criterion of the von Mises type but with modifications to allow for the anisotropy of the samples and also for a built-in compressive stress in the draw direction. In the tensile experiments a sharp neck is usually formed at an angle to the tensile direction and this angle is predicted with good accuracy by an application of the theory of plastic potential.The built-in stress is closely related to the retraction stress which develops when the films are heated but not allowed to contract. In general the tensile yield stress and the tensile modulus are also closely correlated.     

Rapid onset of pulmonary infiltration due to histiocytic lymphoma

Of 269 patients with histoplasmosis, 259 had radiographic manifestations of the disease. Of these, 217 showed multiple or solitary nodules, 28 infiltrates, 25 adenopathy, 5 fibrosing mediastinitis, 5 cavitation (3 infiltrates, 2 nodules), and 1 pleural effusion.     

The effect of boiling water on an amorphous aromatic polyamide

Amorphous poly(sulphonyldi-p-phenylene-α,ω-alkylene dicarboxamides) undergo marked changes during immersion in boiling water. This treatment produces opacity, softening and ultimately blistering and embrittlement of moulded or cast specimens produced from these polyamides. These changes have been shown to be due to a lowering of the glass-transition temperature (T_g) to below 100 °C, and to the acid catalysed, hydrolytic scission of in-chain amide bonds. The stability to boiling water is improved by copolymerisation to raise the T_g and by minimising the total acid content of the polymers. An n.m.r. method for the determination of terminal amine groups in these polyamides is described.     

Reduced nitrite levels and dietary α-tocopheryl acetate supplementation: effects on the colour and oxidative stability of cooked hams

The objective of the present study was to determine the effects of dietary vitamin E supplementation and reduced nitrite levels on the colour stability of cooked hams. Large white × Landrace pigs (male n=6, female n=6) were each subdivided into two groups (n=3) and fed an α-tocopheryl acetate supplemented diet (1000 mg/kg feed) and a basal diet (10 mg/kg feed) for a period of 10 weeks. M. semitendinosus were removed from each pig, divided into light and dark pigmented fractions, vacuum packed and stored at 4°C for 24 h. Muscles were cured with input nitrite levels of 25 and 100 mg/kg meat and were tumbled and massaged for 17 h. Samples were cooked, sliced and overwrapped in a high oxygen permeable film for a storage period of 10 days. Surface colour of hams was measured and expressed as Hunter ‘a’ values. Concentrations of α-tocopherol were significantly (P<0.001) greater in supplemented muscles compared to basal muscles for both male and female pigs. Hams manufactured from male and female supplemented pigs resulted in significantly (P<0.001) higher Hunter ‘a’ values than hams manufactured from male and female pigs receiving the basal diet. Muscles cured with 100 mg nitrite/kg meat formed products with significantly (P<0.001) higher ‘a’ values than those cured with the lower (25 mg/kg meat) nitrite level. Hams manufactured from supplemented muscles, treated with 25 mg nitrite/kg meat showed significantly (P<0.05) higher Hunter ‘a’ values than hams manufactured from basal muscles, treated with 100 mg nitrite/kg meat. Hams manufactured from female porcine muscles had significantly (P<0.001) higher ‘a’ values than hams from male muscles during the 10 days of simulated retail display. No such gender differences were observed for TBARS values.     

Adolescent involvement in anti-social and delinquent behaviours: Predicting future injury risk

The purpose of this study was to challenge the broadly based focus of injury prevention strategies towards concern with the needs of young adolescents who engage in multiple anti-social and delinquent behaviours. Five hundred and forty 13–14-year olds reported on injuries and truancy, violence, illegal road behaviours, drug, and alcohol use. Engagement in these behaviours was found to contribute to the likelihood of an injury. Those engaging in the most anti-social and delinquent behaviours were around five times more likely to report medically-treated injuries in the past three months. Their likelihood of future injury was 1.8 times more likely when they were followed up three months later. The engagement in multiple delinquent and illegal behaviours thus significantly increased the likelihood of injury and identifies a particularly vulnerable group. The findings also suggest that reaching these young people represents a key target for change strategies in injury prevention programs.     

Materials for Bio‐inspired Optics

Bio‐inspired optical systems have the potential to transform the process of image collection and analysis in the future. Through simplicity and dynamics these collection systems may provide multiple functions with an excellent level of reliability. From the graded index of the fish‐eye to the hyper‐acuity of the compound eye, nature has provided function with amazing simplicity. This article reviews a select number of biological vision systems and the unique material behaviors that rise to these characteristics. We introduce the materials chemistry and morphological complexity that enables the biological system behavior.     

19—HEAT-SETTING OF DRAWN POLYMERIC FIBRES: ANOMALOUS TWIST RECOVERY

An investigation is reported in which anomalous negative recovery, or ‘overtwist’, occurred when drawn fibres of poly(ethylene terephthalate) (PET) and nylon 6.6 were heat-set in torsion above a certain temperature T _s*. For the samples of PET and nylon 6.6 studied, and the chosen setting conditions. T _s* was found to be 151 ± 2°C and 133 ± 2°C, respectively. Overtwist was found to decrease with increasing axial tension or after a prior heat-setting treatment without twist. The existence of overtwist and its dependence on twist level and axial tension are explained in terms of the theory of thermoelasticity of a twisted filament. Theory predicts that overtwist will always occur when drawn polymeric filaments are heat-set in torsion at a sufficiently high temperature and setting time.