Preliminary Trials on juvenile Macrobrachium rosenbergii Production under modified Static 'Green water' Conditions

The methods of juvenile production of Udang Galah (Macrobrachium rosenbergii) have been documented by several workers (ling, 1969 .. Ling and Costello, 1976 .. Fujimura 7966, 1967, 1968, 1972 .. Fujimura and okomoto, 1970,. Sandifer etl.1976). The methods given by these workers involve intensive hatchery management such as frequent water change and cleaning of larval tanks to ensure good sanitation. Such a technique would involve wastage of sea water and at the same time is labour intensive. 'to overcome the above mentioned problems a study 'was conducted at the hatchery of the Faculty of Fisheries and marine Science, Serdang, to produce" Udang Galah" juveniles 'Without water change and by using «green water' at salinities 6~8°100 and 12-14% 0 respectively. Previous studies by Cohen et al. (1976) have conclusively shozon that (green water' is an efficient system to remove toxic metabolites such as ammonia from the culture medium. The 'green water' 'which mainly consists of unicellular algae such as Chlorella is produced by expos;'lg 'loater of salim'ty 6°(00 'Which contained Sarothcrodon mossambicus to sunlight (Fujimura

An Evaluation of the Use of Egg Yolk, Artemia nauplii, Microworms and Moina as Diets in Larval Rearing of Helostoma temmincki Cuvier and Valenciennes

Five day old Helostoma temmincki larvae measing 4.6 ± 0.1 mm in total length were stocked into 12 larval culture tanks at the rate of 1000 larvae/tank (l0 larvae/l). The larvae were fed Diet I (Egg yolk), Diet II (Egg yolk + Artemia naupliz), Diet III (Egg yolk +microworms), and Diet IV (Egg yolk + Moina) for iz period of4 weeks. After 1 week of rearing, larvae fed Diet III measun'ng 8. 4 mm total length and 7.0 mg weight were larger than larvae fed the other diets (P < 0.05). A t the end of two weeks, larvae fed Diets II, III and IV were larger than larvae fed Diet I (P < 0.05). FrOm" week 3 onwards, larvae fed Diet IV were consistently larger (P <0.05). This experiment shows that microworms were very suitable as a starter feed and that Moina was suitable for feeding Helostoma temmincki larvae after week 2 under tropical conditions

A Preliminary Study on Induced Spawning of the Catfish Clarias batrachus (Linnaeus) in Malaysia

Ten gravid Clarias batrachus females were administered with a single dose of common carp pituitary homogenate (CPR). Bifore injection, the eggs were light yellow and the diameter rangedfrom 0.94 mm to 1.08 mm. Ovulation occurred approximately 12 hours after the adminstration of CPR. The colour of the eggs turned brown and the diameter rangedfrom o. 99 mm to 1.27 mm. The fertilization rates rangedfrom 10-81%. The eggs hatched after about 30-36 hours of incubation at 26°C to 28°C. The hatching rates ranged from 13-67070

Characterizing anomalies in distributed strain measurements of cast-in-situ bored piles

This paper describes the method of identifying typical defects of bored cast-in-situ piles when instrumenting using Distributed Optical Fiber Strain Sensing (DOFSS). The DOFSS technology is based on Brillouin Optical Time Domain Analyses (BOTDA), which has the advantage of recording continuous strain profile as opposed to the conventional discrete based sensors such as Vibrating Wire strain gauges. In pile instrumentation particularly, obtaining distributed strain profile is important when analysing the load-transfer and shaft friction of a pile, as well as detecting any anomalies in the strain regime. Features such as defective pile shaft necking, discontinuity of concrete, intrusion of foreign matter and improper toe formation due to contamination of concrete at base with soil particles, among others, may cause the pile to fail. In this study, a new technique of detecting such defects is proposed using DOFSS technology which can potentially supplement the existing non-destructive test (NDT) methods. Discussion on the performance of instrumented piles by means of maintained load test are also presented

Analysis of laser absorption on a rough metal surface

We have developed a simple model to estimate the cumulative absorption coefficient of an ultraviolet laser pulse impinging on a pure metal, including the effects of surface roughness whose scale is much larger than the laser wavelength λ. The multiple reflections from the rough surface may increase the absorption coefficient over a pristine, flat surface by an order of magnitude. Thus, as much as 16% (at room temperature) of the power of a 248 nm KrF excimer laser pulse may be absorbed by an aluminum target. A comparison with experimental data is given. © 1997 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71289/2/APPLAB-70-6-696-1.pd

Graphene Transport at High Carrier Densities using a Polymer Electrolyte Gate

We report the study of graphene devices in Hall-bar geometry, gated with a polymer electrolyte. High densities of 6 $\times 10^{13}/cm^{2}$ are consistently reached, significantly higher than with conventional back-gating. The mobility follows an inverse dependence on density, which can be correlated to a dominant scattering from weak scatterers. Furthermore, our measurements show a Bloch-Gr\"uneisen regime until 100 K (at 6.2 $\times10^{13}/cm^{2}$), consistent with an increase of the density. Ubiquitous in our experiments is a small upturn in resistivity around 3 $\times10^{13}/cm^{2}$, whose origin is discussed. We identify two potential causes for the upturn: the renormalization of Fermi velocity and an electrochemically-enhanced scattering rate.Comment: 13 pages, 4 figures, Published Versio