Theoretical estimation of thermodynamic properties of the system PS/PPO on the basis of modified combining rule of Sanchez-Lacombe lattice fluid model

The three scaling parameters described in Sanchez-Lacombe lattice fluid theory (SLLFT), T*, P* and rho* of pure polystyrene (PS), pure poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) and their mixtures are obtained by fitting corresponding experimental pressure volume-temperature data with equation-of-state of SLLFT. A modified combining rule in SLLFT used to match the volume per mer, v* of the PS/PPO mixtures was advanced and the enthalpy of mixing and Flory-Huggins (FH) interaction parameter were calculated using the new rule. It is found that the difference between the new rule and the old one presented by Sanchez and Lacombe is quite small in the calculation of the enthalpy of mixing and FH interaction parameter and the effect of volume-combining rule on the calculation of thermodynamic properties is much smaller than that of energy-combining rule. But the relative value of interaction parameter changes much due to the new volume-based combining rule. This effect can affect the position of phase diagram very much, which is reported elsewhere [Macromolecules 34 (2001) 6291]

Effect of the compatibilization of linear low-density polyethylene-g-acrylic acid on the morphology and mechanical properties of poly(butylene terephthalate)/linear low-density polyethylene blends

A poly(butylene terephthalate) (PBT)/linear low-density polyethylene (LLDPE) alloy was prepared with a reactive extrusion method, For improved compatibility of the blending system, LLDPE grafted with acrylic acid (LLDPE-g-AA) by radiation was adopted in place of plain LLDPE. The toughness and extensibility of the PBT/LLDPE-g-AA blends, as characterized by the impact strengths and elongations at break, were much improved in comparison with the toughness and extensibility of the PBT/LLDPE blends at the same compositions. However, there was not much difference in their tensile (or flexural) strengths and moduli. Scanning electron microscopy photographs showed that the domains of PBT/LLDPE-g-AA were much smaller and their dispersions were more homogeneous than the domains and dispersions of the PBT/ T,T PE blends. Compared with the related values of the PBT/LLDPE blends, the contents and melting temperatures of the usual spherulites of PBT in PBT/LLDPE-g-AA decreased.

Electrocatalytic mechanism for formaldehyde oxidation on the highly dispersed gold microparticles and the surface characteristics of the electrode

Electrocatalytic mechanism for the electrochemical oxidation of formaldehyde (HCHO) on the highly dispersed Au microparticles electrodeposited on the surface of the glass carbon (GC) electrode in the alkaline Na2CO3/NaHCO3 solution and the surface characteristics of the Au microparticle-modified glass carbon (Au/GC) electrode were studied with in situ FTIR spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was found that the final products of HCHO oxidation is HCOO- at the Au/GC electrode and CO2 at the bulk Au electrode. The difference may be ascribed to the different surface characteristics between the Au/GC electrode and the bulk Au electrode. (C) 1999 Elsevier Science B.V. All rights reserved.

Stereochemical effects in mass spectrometry - Determination of the optical purity of enantiomers by mass spectrometry

Due to the difference in reactivity of enantiomers with chiral reagents, it was found that in the Fast Atom Bombardment (FAB) mass spectra of enantiomer mixtures of R-alpha-phenylethylamine and S-alpha-phenylethylamine with a chiral reagent S-phosphorsaeure-(1,1'-bi-naphthyl-2,2'-diylester) (BNP acid), the relative abundance of the characteristic ion is linearly related to the composition of the mixture. We have, therefore, proposed a possible method for the determination of the optical purity of enantiomers by mass spectrometry.

INFLUENCE OF THE OHMIC POLARIZATION EFFECT ON THIN-LAYER SPECTROELECTROCHEMISTRY

The influence of thin-layer resistance in cyclic voltammetry was studied in detail. Under the experimental conditions, a linear relationship between the peak-peak potential difference and the product of the peak current and the resistance was obtained and

EVALUATION OF THE RELIABILITY OF KALMAN FILTERING RESULTS IN INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION-SPECTROMETRY

This paper deals with the evaluation of the reliability of the analytical results obtained by Kalman filtering. Two criteria for evaluation were compared: one is based on the autocorrelation analysis of the innovation sequence, the so-called NAC criterion; the other is the innovations number, which actually is the autocorrelation coefficient of the innovation sequence at the initial wavelength. Both criteria allow compensation for the wavelength positioning errors in spectral scans, but there exists a difference in the way they work. The NAC criterion can provide information about the reliability of an individual result, which is very useful for the indication of unmodelled emissions, while the innovations number should be incorporated with the normalization of the innovations or seek the help of the sequence itself for the same purpose. The major limitation of the NAC criterion is that it does not allow the theoretical modelling of continuous backgrounds, which, however, is convenient in practical analysis and can be taken with the innovations number criterion.

MOLECULAR-WEIGHT DEPENDENCE OF THE GLASS-TRANSITION OF CYCLIC POLYSTYRENE

The glass transition temperature (T(g)) of cyclic polystyrene was measured by differential scanning calorimetry. There was a marked difference in the glass transition behaviour between cyclic and linear polystyrene. In the low molecular weight region (M(n) < 5 x 10(3)), the T(g) of the cyclic polystyrene increased with decreasing M(n), contrary to that of linear polystyrene. With M(n) higher than 5 x 10(3), the T(g) of cyclic polystyrene increased with increasing M(n). The T(g) of cyclic and linear polystyrene approached the same constant value when the M(n) was high enough (M(n) > 10(5)). Combining the results of specific volume, it is believed that the variation of T(g) with molecular weight does not depend only on free volume effects but that configurational entropy is also an important factor.

Population genetic structure of crimson snapper Lutjanus erythropterus in East Asia, revealed by analysis of the mitochondrial control region

The population genetic structure of the crimson snapper Lutjanus erythropterus in East Asia was examined with a 427-bp hypervariable portion of the mtDNA control region. A total of 262 samples were collected and 75 haplotypes were obtained. Neutrality tests (Tajima's and Fu's) suggested that Lutjanus erythropterus in East Asia had experienced a bottleneck followed by population expansion since the late Pleistocene. Despite the low phylogeographic structures in mtDNA haplotypes, a hierarchical examination of populations in 11 localities from four geographical regions using analysis of molecular variance (AMOVA) indicated significant genetic differentiation among regions (Phi(CT) = 0.08564, p < 0.01). Limited gene flow between the eastern region (including a locality in the western Pacific Ocean and two localities in the East Sea) and three geographic regions of the South China Sea largely contributed to the genetic subdivision. However, comparisons among three geographic regions of the South China Sea showed little to no genetic difference. Populations of Lutjanus erythropterus in East Asia are inferred to be divided into two major groups: an eastern group, including populations of the western Pacific Ocean and the East Sea, and a South China Sea group, consisting of populations from northern Malaysia to South China. The results suggest that fishery management should reflect the genetic differentiation and diversity in East Asia. (c) 2006 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved.

Seeding nets with neutral spores of the red alga Porphyra umbilicalis (L.) Kutzing for use in integrated multi-trophic aquaculture (IMTA)

Nets in traditional Porphyra mariculture are seeded with conchospores derived from the conchocelis phase, and spend a nursery period in culture tanks or calm coastal waters until they reach several centimeters in length. Some species of Porphyra can regenerate the foliose phase directly through asexual reproduction, which suggests that the time, infrastructure, and costs associated with conchocelis culture might be avoided by seeding nets with asexual spores. Here, we present work from a short-term mariculture study using nets seeded with asexual spores (neutral spores) of a native Maine species of Porphyra. Porphyra umbilicalis (L.) Kutzing was selected for this proof of concept research because of its reproductive biology, abundance across seasons in Maine, and evidence of its promise as a mariculture crop. We studied the maturation, release, and germination of the neutral spores to develop an appropriate seeding protocol for nets, followed by development of a nursery raceway to provide an easily manipulated environment for the seeded nets. Neutral spores were produced throughout the year on the central Maine coast,however, there was a temporal variability in the number and survival of released neutral spores, depending upon thallus position in the intertidal zone. Small thalli were strictly vegetative, but most thalli reproduced by neutral spores- sexual reproduction was absent. Neutral spores germinated quickly at 10 and 15 'C, but germination was delayed at 5 degrees C. Unlike some algal zygotes and spores, neutral spores of R umbilicalis required light to germinate; however, irradiances of 25 and 100 mu mol photons M-2 S-1 were equally sufficient for germination. Rafts of seeded nets were deployed in Cobscook Bay, Maine, at two distances from salmon aquaculture pens and at a control site on a nearby, fallow aquaculture site (no salmon). There was no difference in nitrogen content of harvested thalli; however, both the density and the surface area of harvested thalli were different among the sites. The possible causes of these differences are discussed in the context of potential use of P umbilicalis in IMTA. (C) 2007 Elsevier B.V. All rights reserved.

Loss of allele diversity in introduced populations of the hermaphroditic bay scallop Argopecten irradians

The bay scallop Argopecten irradians is a hermaphroditic bivalve native to the Atlantic coast of the United States that was introduced to China for aquaculture production in 1982. It now supports a major aquaculture industry in China. Introduced species often start with limited genetic variability, which is problematic for the further selective breeding. Bay scallop aquaculture is exclusively hatchery based and as the initial introduction consisted of only 26 scallops, there have been concerns about inbreeding and inbreeding depression in cultured populations in China. In this study, eleven simple sequence repeat (SSR) markers were used to compare genetic variation in cultured populations from China with that in a natural population from the east coast of America. Although the difference in heterozygosity was small, the Chinese populations lost 9 of the 45 alleles (20%) found in the wild population. The reduced allele diversity suggests that the Chinese bay scallop populations experienced a bottleneck in genetic diversity that remains significant despite several recent introductions of new stocks aimed at expanding the gene pool. The loss of allele diversity may affect future efforts in selective breeding and domestication, and results of this study highlight the need for additional introductions, advanced breeding programs that minimize inbreeding and continued genetic monitoring. (c) 2007 Elsevier B.V. All rights reserved.

Sea surface height and transport stream function of the South China Sea from a variable-grid global ocean circulation model

A fine-grid model (1/6degrees) covering the South China Sea (SCS), East China Sea and Japan/East Sea, which is embedded into a coarse-grid (3degrees) global model, was established to study the SCS circulation. In the present paper, we report the model-produced monthly and annual mean transport stream functions and sea surface heights(SSH) and their anomalies of the SCS. Comparison to the TOPEX/Poseidon data shows that the model-produced monthly sea surface height anomalies (SSHA) are in good agreement with altimeter measurements. Based on the results, the circulation of the SCS, especially the upper layer circulation, is discussed. In the surface layer, the western Philippine Sea water intrudes into the SCS through the Luzon Strait in autumn, winter and spring, but not in summer. However, as far as the whole water column is concerned, the water intrudes into the SCS through the Luzon Strait all the year round. This indicates that in summer the water still intrudes into the SCS in the subsurface and intermediate layers. The area near the northern continental slope of the SCS is dominated by a cyclonic circulation all the year round. The SCS Southern Anticyclonic Gyre, SE Vietnam Off-Shore Current in summertime and SCS Southern Cyclonic Gyre in wintertime are reproduced reasonably. The difference between the monthly averaged SSH and SSHA is significant, indicating the importance of the mean SSH in the SCS circulation.

Potential of the seaweed Gracilaria lemaneiformis for integrated multi-trophic aquaculture with scallop Chlamys farreri in North China

In this study the red alga, Gracilaria lemaneiformis, was cultivated with the scallop Chlamys farreri in an integrated multi-trophic aquaculture (IMTA) system for 3 weeks at the Marine Aquaculture Laboratory of the Institute of Oceanology, Chinese Academy of Sciences (IOCAS) in Qingdao, Shandong Province, North China. The nutrient uptake rate and nutrient reduction efficiency of ammonium and phosphorus from scallop excretion were determined. The experiment included four treatments each with three replicates, and three scallop monoculture systems served as the control. Scallop density (407.9 +/- 2.84 g m(-3)) remained the same in all treatments while seaweed density differed. The seaweed density was set at four levels (treatments 1, 2, 3, 4) with thallus wet weight of 69.3 +/- 3.21, 139.1 +/- 3.80, 263.5 +/- 6.83, and 347.6 +/- 6.30 g m(-3), respectively. There were no significant differences in the initial nitrogen and phosphorus concentration between each treatment and the control group (ANOVA, p > 0.05). The results showed that at the end of the experiment, the nitrogen concentration in the control group and treatment 1 was significantly higher than in the other treatments. There was also a significant difference in phosphorus concentration between the control group and the IMTA treatments (ANOVA, p < 0.05). Growth rate, C and N content of the thallus, and mortality of scallop was different between the IMTA treatments. The nutrient uptake rate and nutrient reduction efficiency of ammonium and phosphorus changed with different cultivation density and time. The maximum reduction efficiency of ammonium and phosphorus was 83.7% and 70.4%, respectively. The maximum uptake rate of ammonium and phosphorus was 6.3 and 3.3 A mu mol g(-1) DW h(-1). A bivalve/seaweed biomass ratio from 1:0.33 to 1:0.80 (treatments 2, 3, and 4) was preferable for efficient nutrient uptake and for maintaining lower nutrient levels. Results indicate that G. lemaneiformis can efficiently absorb the ammonium and phosphorus from scallop excretion and is a suitable candidate for IMTA.

Identification of factors affecting the growth and survival of the settling Japanese flounder larvae, Paralichthys olivaceus

A series of experiments were conducted to identify the factors that affected the growth and survival of the settling flounder larvae Paralichthys olivaceus. Settling larvae 24 days after hatching (DAH) were reared in 10-l experimental tanks up to 40 DAH, and two of the following factors were changed as controlled factors in each experiment: light regime (24L:0D or 12L:12D), prey density (1500, 3000, or 5000 Artemia l(-1)), shelter (sand or no sand) and stocking density (5, 10, or 15 fish l(-1)). Early settling larvae (24-35 DAH) experienced little mortality (less than 10% of the overall mortality) that was not significantly affected by above factors. In contrast, late settling larvae (36-40 DAH) suffered high cannibalistic mortality which was significantly influenced by each of the above factors. Larvae experienced significantly lower mortality at 10 fish l(-1) level than at other densities. Larvae at 15 fish l(-1) level had higher mortality than at 5 fish l(-1) when all other factors were identical. Larvae at 3000 and 5000 Artemia l(-1) treatments survived significantly better than at 1500 Artemia l(-1), but no significant differences in larval mortality were found between the two higher densities. Larvae suffered higher mortality at low prey density or at the absence of sand when they were exposed to longer photoperiod. Low stocking density significantly improved the growth of the settling larvae. The average daily instantaneous growth rate (G) at 5 and 15 fish l(-1) treatments were 0.050 and 0.034, with the coefficient of variation (CV) in final length at 16.4 and 23.5, respectively. Daily instantaneous growth rate increased significantly from 0.033 in the 1500 Artemia l(-1) to 0.041 and 0.045 in the 3000 and 5000 Artennia l(-1), respectively, but no significant difference in larval growth existed between the two higher prey densities. These findings suggested that the optimal prey density for growth and survival of the settling flounder larvae at a stocking density of 5 - 15 fish l(-1) was around 3000 Artemia l(-1) . Larvae that were exposed to 24L showed 20% increase in growth ( G = 0.046, CV = 18.7) than those exposed to 12L ( G = 0.037, CV = 20.5). Longer exposure to light significantly improved larval growth, provided sufficient food was available. Sand substrate did not show significant effects on larval growth, possibly because the larvae spent most of the time swimming or feeding in the water column during this stage. (C) 2003 Elsevier Science B.V. All rights reserved.

Comparison of the total amount of eggshell pigments in Dongxiang brown-shelled eggs and Dongxiang blue-shelled eggs

Based on the knowledge of the heme biosynthetic and metabolic pathway and the structures of biliverdin and protoporphyrin, experiments were carried out to compare the difference between the total quality of eggshell pigments in blue-shelled eggs and brown-shelled eggs from the same population (Dongxiang, China) and to analyze the correlation between the quantity of protoporphyrin and biliverdin in the 2 kinds of eggshells. It was found that there was no significant difference between the total quantity of eggshell pigments in Dongxiang blue-shelled eggs and Dongxiang brown-shelled eggs (P = 0.9006), and a highly significant positive correlation between the quantity of protoporphyrin and biliverdin in blue eggshells (P < 0.01) and a significant positive correlation between the quantity of protoporphyrin and biliverdin in brown eggshells (P < 0.05). These results suggested that eggshell protoporphyrin and eggshell biliverdin probably derived from common precursor material.

Diurnal and seasonal variations of UV radiation on the northern edge of the Qinghai-Tibetan Plateau

We monitored UVA, UVB, and solar radiation from August 2001 to 2003 on the northern Qinghai-Tibetan Plateau to characterize the diurnal and seasonal variations of UV radiation on the world's highest plateau. Daily UVB radiation and the ratio of UVB to total solar radiation increased significantly when the atmospheric ozone concentration decreased as estimated by the total ozone mapping spectrometer (TOMS), as well as when cloud coverage decreased. The UVB/UVA ratio also showed a significant increase when the TOMS ozone concentration decreased in the morning. The seasonal variation pattern of UVB, however, was closely correlated with solar elevation but was little affected by the seasonal pattern of the atmospheric ozone amount. Compared to observations from the central plateau, the magnitude of the UVB increase attributed to ozone depletion was smaller at the northern edge. The study suggests that the temporal variation of ground UV radiation is determined by both solar elevation and the ozone amount, but the spatial difference on the plateau is likely to be ascribed mainly to the spatial variation of the ozone amount. (c) 2007 Published by Elsevier B.V.