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Many studies suggest that severe plastic deformation (SPD) can produce nanocrystalline metallic structures. Based on structural characterization using transmission electron microscopy, dislocation cellular structures are indeed produced by SPD. However, should we regard such nanocellular structures as nanocrystalline? In other words, can SPD alone produce a well-defined nanocrystalline structure? In this study, we applied SPD to surfaces of Cu–30Ni alloy specimens by repeated punching and divided them into two groups; one of which was subjected to subsequent annealing (recovery treatment) and the other was not. Both groups showed similar nanocrystalline morphologies under an atomic force microscope. However, their surface and electrochemical properties are quite different, evidenced by differences in the electron work function, electrochemical polarization behavior, and other properties. This indicates that simply categorizing the SPD-produced structures with cellular domains as nanocrystalline structures...

Wu, L.Y., Fang, Y.J., Tan, R.B. and Shi, K.J. 2009. A comparison of cecal microflora and volatile fatty acid concentration in goslings fed diets supplemented with or without a dried Bacillus subtilis culture. J. Appl. Anim. Res., 36: 231–234. Bacillus subtilis, α Gram-positive, aerobic, nonpathogenic, endospore-forming bacterium was evaluated for its probiotic potential in the cecum of goslings. One hundred and twenty one-day-old goslings, randomly divided into two dietary treatments, were fed basal diet without or with 250 mg dried Bacillus subtilis culture (DBSQ/kg for 4 wk. The cecal chyme of 24 goslings on each treatment was collected for analyses at 28 d of age. Lactobacillus and Bifidobacterium counts were significantly increased and the harmful bacteria (P

1. The study was conducted to evaluate the effects of a dried Bacillus subtilis culture (DBSC) on growth performance and nutrient retention of goslings. 2. A total of 240 goslings were randomly divided into 4 dietary treatments with 6 replicates of 10 goslings per pen from 0 to 4 weeks of age. The 4 treatments consisted of a basal diet containing neither antibiotics nor DBSC (control), basal diet supplemented 5 mg Flavomycin/kg, and basal diet supplemented with 250 or 500 mg DBSC/kg. 3. Body weight and feed consumption were measured with pen as the experimental unit at 14 and 28 d of age, and excreta collections from each pen were carried out to determine nutrient retention ratio during the 4th week. 4. The results showed that the diet supplemented with 250 mg DBSC/kg increased average daily gain (ADG) by 6.9%, reduced average daily feed intake (ADFI) by 3.9%, and improved feed conversion ratio (FCR) by 10.3% in a 0-28 d feeding period, compared with the control diet. However, the diet containing 500 mg DBSC/kg did not effect these performance of goslings. 5. The goslings given the diet with 250 mg DBSC/kg had similar ADG, lower ADFI and significantly lower FCR to or than the goslings fed on the Flavomycin diet. 6. The results also showed that dietary DBSC supplementation improved dry matter and energy retention of goslings. 7. This study indicated that the diet containing a dried B. subtilis culture at 250 mg/kg offered large benefits to the growth performance of goslings, and these benefits could equal or exceed those from Flavomycin. It is suggested that the growth promoting effect of DBSC may be attributed to the improvement in the availability of dietary nutrients.

This paper successfully subgroups firm-initiated suspensions into ‘favourable news’ and ‘unfavourable news’ suspensions. The ‘favourable news’ group experiences significantly positive abnormal returns around the event date. The ‘unfavourable news’ group, on the other hand, suffers a prolonged decline. The high trading volumes in the pre- and the post-suspension periods suggest that firm-initiated suspensions on the Singapore Exchange involve the release of new sensitive information. Firm-initiated trading suspensions are also accompanied by increases in post-suspension return volatility.

In this study, we look at the effects of using different offering methods and examine whether the auction system is a better way of rationing IPOs in the sense of reducing the degree of underpricing. Preliminary findings show that IPOs offered via the auction system appear to have lower underpricing. However this is not confirmed by cross-sectional regression analysis. Results show that only the subscription rate is significantly associated with the degree of underpricing. The other variables such as the market of listing, the price earnings ratio at time of issue and the first day relative volume are not significantly related to the underpricing. The second part of the study compares fixed price initial public offerings (IPOs) listed on the Stock Exchange of Singapore Dealing and Automated Quotation System (SESDAQ), the second tier stock market in Singapore, with fixed price IPOs listed on the Main Board. The PE ratios at time of issue and subscription rates of SESDAQ IPOs are significantly lower than Ma...

This study examines the daily stock returns in the Singapore market over a 20 year period from 1975 to 1994. Results indicate the existence of four calendar anomalies. They are the January effect, the day-of-the-week effect, the turn-of-the-month effect and the holiday effect. Subperiod analysis, however, reveals a weakening of these anomalies over time.

The dry sliding wear and friction behaviour of cast Al-Si alloy and composites containing 5·0, 8·0, 12·0, and 16·0 vol.-% alumina short fibres was investigated by means of a block on ring (bearing ...

A theoretical formulation based on maximum entropy principles is presented to predict the droplet size and velocity distributions of sprays in an isothermal environment. The joint droplet distribution function is derived subject to the constraints of mass flow rate, momentum flux, and two modes of energy fluxes (kinetic and surface). A simpler model, which reduces the number of constraints by three, is derived by choosing an adequate velocity integration range. This maximum entropy principle spray model is tested by comparing the calculated distributions with experimental measurements presented by the authors for a hollow cone, non-swirl spray nozzle and the experimental results obtained by other researchers for hollow cone, swirl spray nozzles. For a specific droplet size, the droplet velocity distribution is Gaussian. The droplet size distribution is much more complicated; three types of distributions may occur-positively skewed mono-modal, uniform size (in the limit approaching a delta functio...

A new casting process for fabricating short fibre reinforced metal matrix composites via the centrifugal force infiltration of fibre preforms with molten aluminium alloys is described. The effect of processing variables, such as pouring temperature, preheated mould temperature, and time of application of centrifugal force, on the infiltration kinetics and resultant microstructure is discussed. Composites having fibre volume fractions of 4·5, 8·0, 12, and 16% were obtained via this method. Comparisons with existing infiltration technology and the mechanical properties of the composite are presented.MST/2000

Solvatochromic parameters are the best descriptors of solute retention in RPLC. Accurate prediction of capacity factors for 26 solutes is obtained with binary mixtures of organic modifier/water in the vol/vol range 10–100%. Example of application is given.

Conditions of microencapsulation by in situ polycondensation, using melamine-formaldehyde as wall material, are influenced by the chemical nature of the core to encapsulate. In our study concerning the encapsulation of a photopolymerizable phase containing an electrically charged compound, it was necessary to modify the experimental process to obtain capsules of good quality. We used the factorial design method of screening by utilization of an asymmetric matrix, according to the collapsing principle of Addleman. The advantage of this method is that it allows determination of the simultaneous influences of the 11 experimental parameters involved in this preparation. The calculation method can be applied to more than two levels for some of the factors. The continuously varying parameters were altered between two extreme levels, chosen to allow encapsulation. For discontinuous factors, such as the molecular weight of the modifying system or nature of the aminoplast, we used the commercially available compounds, respectively three and four kinds. The results of the obtained capsules were determined by comparing microphotographic pictures. With 16 experiments we found four more factors influencing quality of capsules. We also determined the most favourable levels for the other seven parameters. The results allowed us to find optimal conditions in the experimental field. We obtained capsules of a satisfactory quality for this purpose, using only minimum experimentation.

Aestivation patterns in Bulinus rohlfsi and B. globosus were studied by digging transects across the floor of their dried habitats and by monitoring changes in snail population structure during the period when the habitats were flooded. Bulinus rohlfsi, which inhabited a small man-made lake, was found to aestivate towards the bottom of its habitat, aestivation occurring during the last six weeks before the lake dried. The data on B. globosus from a temporary pool are less complete, but they show that this species also aestivates at the bottom of its habitat and can be found buried at depths up to 3 cm. A wide size range of both species of snail were found to aestivate, but there was differential mortality of young B. rohlfsi soon after the lake re-fllled, and the optimally surviving size group of B. globosus was 9 mm. The beginning of aestivation in B. rohlfsi did not correlate with any of the physical parameters measured, but it coincided with the dying off of a bloom of unicellular algae. The importance...

Stool and urine samples from 813 schoolchildren and adults from the Tomas and Rimin Gado dam areas of Kano State, Nigeria, showed Schistosoma haematobium to be present at both localities with prevalences of 26.6 and 36.8%, respectively. No cases of S. mansoni were found. The prevalence and intensity of S. haematobium was low and similar in both study areas. Statistical analysis revealed a correlation between prevalence and location, but no evident association with professed patterns of water contact. Investigation of 165 freshwater habitats throughout the state revealed the presence of a number of potential snail intermediate host species, namely Bulinus senegalensis, B. forskali, B. globosus, B. rohlfsi and Biomphalaria pfeifferi. The most widespread species was Bulinus senegalensis, which inhabited shallow pools and excavations on a variety of substrata. Its habitats were typically devoid of aquatic vegetation and included those with highly turbid waters and conductivities as low as 11 microseconds. Bulinus forskali was by contrast relatively rare, occurring in more permanent water courses, although it was often found in mixed populations with B. senegalensis. Bulinus globosus also occurred in seasonally rainfilled pools, but was confined to areas south of the 12 degrees N parallel, and its habitats tended to have a well-developed aquatic flora and clear water. The dominant species in man-made lakes was B. rohlfsi, which occurred in both the Tomas and Rimin Gado reservoirs. Biomphalaria pfeifferi was also primarily lake dwelling, although all species save B. senegalensis were found in irrigation canals.

Anaerobic sludge digestion may be divided into two stages: hydrolysis ‐acidogenesis and methanogenesis. These phases may be separated to improve the efficiency of the digestion. The hydrolysis of sludge was studied in laboratory fermenters with the aim of improving volatile fatty acids production during the first phase. The influence of pH, temperature and agitation speed was studied. A mathematical approach to this problem was used by means of a statistical tool : methodology experimental research (M.E.R.). The best running conditions for hydrolysis were found to be : pH = 6.8, temperature = 50°C and agitation speed = 545 rpm.

Efficient experimental design may be used to maximise the information available from a given number of experiments (1, 2, 3, 4). In the development of new molecules the amount of drug available for formulation studies is often restricted. Thus in studying a given process the experiment is designed so that the necessary information is obtained given there is only enough material for a limited number of operations.We have studied the effects of process variables on the characteristics of a conventional tablet formulation of a soluble drug; the factorial design was optimised by an exchange algorithm.