[Effects of Sediment Microenvironment on Sedimentary Phosphorus Release Under Capping]

The sediment microenvironment has an important effect on the release of endogenous phosphorus. In this study, the influence of two different in-situ covering materials on the sediment microenvironment were compared, and the controlling effect of endogenous phosphorus release were studied. The sediment microenvironment was represented by the concentration of NH₄⁺-N, Fe²⁺ in interstitial water, and microbial activity. The results showed that the concentrations of NH₄⁺-N and Fe²⁺ were lower under ACPM coverage than those of the Phoslock^® group, and the microbial activity was higher, indicating that the redox potential of ACPM coverage was higher than that of Phoslock^®. Furthermore, the bottom sediment microenvironment was in an aerobic state. Compared with the Phoslock^® group, the DIP concentrations in both the overcover water and porewater in the ACPM group were higher, indicating that Phoslock^® was superior to ACPM with respect to the phosphate adsorption capacity, suggesting that the sediment microenvironment was not the only criterion for phosphorus adsorption. In the fixation process of endogenous phosphorus, both of the covering materials were conducive to the fixation of inter phosphorus, and Ca-P increased significantly. On the other hand, oxidizing ACPM led to an increase in NH₄Cl-P and a significant decrease in Fe/Al-P. This promotes the release of active phosphorus, which is conducive to the cleaning of the sediment and phosphorus release.

[Adsorption Behavior of Phosphate by CaO2 Remolded Sediment]

This study simulated the state of CaO₂ loss after in situ coverage and examined the bottom 2 cm of sediment after restoration. Observations and elemental analysis of the sediment using scanning electron microscopy (SEM) and X-ray energy spectrometry (EDX) were also performed. The CaO₂ remodeling notably changed the structure of the sediment; most of the organic matter and iron-manganese oxide attached to the sediment surface was removed, the porosity of the sediment particles increased, and the Ca²⁺ content was also increased. CaO₂ remodeling stabilized the endogenous phosphorus in the sediment; total phosphorous (TP) was reduced by approximately 20% and potential active phosphorus content was reduced by approximately 30%. Furthermore, the contents of Ca-P and Res-P were significantly increased. The amount of phosphorus released from the remodeled sediment under anaerobic conditions was significantly lower than the original sediment, indicating that the CaO₂ remodeling greatly reduced the risk of endogenous phosphorus release. The Langmuir model was more suitable than the Freundlich and Dubinin-Radushkevich models for describing the isothermal adsorption behavior of the CaO₂ remodeling, which significantly improved the adsorption capacity of the sediment with respect to phosphate from 1.44 mg·g^-1 to 20.91 mg·g^-1. The mechanism of adsorption was switched from chemical adsorption to physicochemical adsorption. In addition, the adsorption kinetics of the CaO₂ remodeled sediment with respect to phosphate could be best described using the quasi-second-order kinetic model.

[Effect of Oxidation Strengthening on In-situ Phosphorus Immobilization of Calcium Hydroxide]

In this research, calcium hydroxide[Ca(OH)₂] and hydrogen peroxide (H₂O₂) were injected into the bottom mud in the form of plum blossom scatterers to investigate the effect on the control of endogenous phosphorus. The results showed that Ca(OH)₂ used singly effectively immobilized in the order of 90% of endogenous phosphorus approximately 20 mm below the sediment-water interface (SWI); however, at the same time, the anaerobic environment was enhanced, resulting in the transformation of stable phosphorus to easily released phosphorus and the accumulation of potential active phosphorus. Nevertheless, the addition of H₂O₂ greatly reduced the amount of potential active phosphorus in deep sediments after adding Ca(OH)₂. The vertical diffusion depth of Ca(OH)₂ in the sediments was significantly increased, having an influence across the depth range of 0-40mm below the SWI; the improvement at depths greater than 40 mm was not notable, which was mainly attributed to an 18-fold increase of redox potential due to the addition of the oxidant. The change of phosphorus forms in the sediment also demonstrated the excellent immobilization effect of the oxidant on phosphorus. In the 0-20 mm layer, the content of readily released phosphorus decreased significantly, while compared with a control test, Ca-P increased by approximately 10%. However, at greater depths, the amount of easily released phosphorus decreased and the rate of Ca-P increase gradually slowed.

[Effect of Calcium Peroxide Composite Tablets on Water Remediation and Phosphorus Control in Sediment]

Two types of calcium peroxide composite tablets (CPCTs) were prepared, and the inhibition effect on the release of endogenous phosphorus and the influence on the overlying water by mixed-dosing were investigated. The CPCTs were made of calcium peroxide (CaO₂), calcined water purification sludge, and hydroxypropyl methylcellulose (HPMC), which were directly pressed into composite tablets, among which Tablet-B (T-B) contained ferrous sulfate (FeSO₄) and Tablet-A (T-A) did not. Both the tablets agreed well with the Langmuir and Freundlich isothermal models; the theoretical maximum adsorption capacities of T-A and T-B on phosphorus were 110.908 mg·g^-1 and 106.390 mg·g^-1, respectively. Compared with the control group, the pH of overlying water was increased, the concentration of Chl-a was decreased by 42.75% and 60.82%, and the DO was increased by 53.73% and 63.30% in group A and B, respectively. The DIP of the overlying water decreased significantly by 54.93% and 25.11% in group A and B, respectively. For the interstitial water in sediment, the DIP in layer Ⅰ (0-2 cm) decreased significantly by 74.81% and 65.66% in group A and B, and the DIP in layer Ⅱ (2-4 cm) decreased significantly by 46.23% in group B, but not obviously in group A. The DIP in layer Ⅲ (4-6 cm) remained unchanged in group A and B. For phosphorus fractions in sediment, the proportion of NH₄Cl-P in TP was significantly increased (layer Ⅰ: 16.87% and 13.11%; layer Ⅱ: 12.99% and 11.02%, in group A and B, respectively), and the proportion of Al-P in TP was significantly decreased (layer Ⅰ: 7.58% and 13.91%; layerⅡ: 9.86% and 7.28%, in group A and B, respectively). The other phosphorus fractions did not change significantly. Both T-A and T-B dosing can improve the microbial activity of the surface sediment, though T-A can improve the microbial activity more significantly.

[Phosphate Control Effect and Water Body Remediation of Magnesium Modified Reed Biochar]

Adding biochar from harvested reed to sediments is a new method to control the release of sedimentary phosphorus. Three types of Mg-modified biochars were prepared by pyrolysis of reed modified by magnesium chloride at 300, 450, and 600℃.The phosphate adsorption characteristics of the three types of biochars were analyzed by isothermal adsorption experiments. Biochar MBC-450 with good phosphate adsorption effects was selected as the material for the following experiments. Taking the sediment and overlying water of a campus river as the experimental object, we studied the adsorption of phosphate in overlying water and the control of sedimentary phosphorus by Mg-modified biochar under different dosage modes (mixing and covering). The concentration of DIP in the overlying water could be effectively reduced by biochar mixing and covering, and the accumulative phosphorus adsorption capacity increased by 17.3% (mixing) and 11.7% (covering) compared with that of the control. The control effect of sedimentary phosphorus by biochar mixing was more obvious; the DIP in sedimentary water decreased by 14.7%, 18.9%, and 35.36% from 0-2 cm to 4-6 cm compared with the control. The DIP in sedimentary water decreased by 33.3%, -28.2%, and 12.9% when covered with biochar. Compared with the control, the proportion of NH₄ Cl-P in the sediment of 0-2 cm and 2-4 cm increased by 15% and 15% (mixing) and 12% and 2% (covering), respectively, while BD-P in TP decreased by 7% and 9% (mixing) and 6% and 3% (covering), respectively, and the Al-P in TP decreased by 7% and 6% (mixing) and 7% and -1% (covering), respectively. The other forms of phosphorus did not change significantly. Biochar mixing and covering can both improve the microbial activity in surface sediment, and biochar mixing can improve the microbial activity in deeper sediments more significantly.

[Adsorption Properties of Sludge-hydrochar for Methylene Blue]

A low-cost and efficient adsorbent, based on sewage sludge, was prepared by hydrothermal carbonization. The sludge-hydrochar was prepared at different temperatures (160, 190, 220, and 250℃) and different reaction times (1, 4, 8, and 16 h). It was applied to the adsorption of methylene blue (MB) in water. This study analyzed the structure and physicochemical properties of hydrochar by BET, FT-IR, and zero charge points. In addition, we investigated the optimum hydrothermal conditions for the preparation of adsorbents and adsorption properties for MB by experiments. Studies have shown that 190℃ and 4 h were the best hydrothermal conditions for the preparation of adsorbent (SS190-4). SS190-4 has the largest specific surface area (11.916 m²·g^-1) and the best removal rate (96.44%) for methylene blue (MB). The adsorption of MB is more favorable when the solution is alkaline. The adsorption conforms to the Langmuir isotherm equation, and the maximum model adsorption capacity for MB is 400 mg·g^-1. When the concentration of hydrochar is 0.5 g·L^-1, it is more economical and reasonable. When there are coexisting ions in the solution, the adsorption capacity of hydrochar to MB is inhibited. The adsorption process of MB by hydrochar conforms to the quasi-secondary kinetic model, which is a spontaneous exothermic reaction.

[Phosphate Adsorption from Water on CaO2-loaded Magnetic Diatomite]

In this study,magnetic diatomite was used as a carrier to load calcium peroxide(CaO₂) nanoparticles,fabricating a high efficiency phosphate adsorption and recovery composite material(MDCP).The micromorphology, inner structure,crystalline constituents and element composition of MDCP were characterized by SEM,EDX-mapping,XRD, XDS, and VSM,respectively.The adsorption isotherm data of MDCP exhibited good agreement with the Langmuir isotherm model. According to the Langmuir model,when T=20℃,the maximum monolayer phosphate adsorption capacities can reach 191.84mg·g^-1 for MDCP. The isotherm and kinetics studies showed that MDCP has a regulating effect on the pH of the solution,which can maintain the pH of the solution at the level where adsorption of phosphate occurs on MDCP as a chemisorption process. pH plays a important role on the adsorption of phosphate by MDCP,the pH of effective adsorption ranges from 4 to 10,and the pH of the adsorbed solution can still be maintained in the range of 7 to 9.The MDCP exhibited a high selective adsorption for phosphate in the presence of anions,including Cl^-, SO₄^2-, CO₃^2-, HCO₃^2-, F^-, and NO₃^-.The recovered MDCP could be desorbed by HCl solution,and after desorption, the phosphate removal rate of MDCP after re-loading CaO₂ could still reach 70% of the initial adsorption.

[Environmental Significance of Phosphorus Fractions of Phytoplankton-and Macrophyte-Dominated Zones in Taihu Lake]

It is of great importance to study the environmental significance of phosphorus fractions in overlying water and sediments of typical phytoplankton-and macrophyte-dominated zones. It will help to clarify the process of phosphorus migration and transformation in the sediment-water interface, and has practical significance for understanding the eutrophication process and its treatment in different regions of Taihu Lake. The investigation was conducted within typical phytoplankton-and macrophyte-dominated zones of Taihu Lake over four seasons to analyze the spatial and temporal differences between phosphorus fractions in water and sediments, and reveal their environmental significance. The results showed that:① Total phosphorus (TP), total soluble phosphorus (DTP), dissolved inorganic phosphorus (DIP), and particulate phosphorus (PP) in the overlying water of phytoplankton-dominated zones were much higher than those in macrophyte-dominated zones. Most of them showed seasonal characteristics, which were higher in summer and autumn than in winter and spring. PP is the main component of TP, accounting for 71.8% to 89.6%. A similar distribution character was found in the content of chlorophyll (Chl-a) compared with phosphorus concentration in overlying water. ② The concentration of TP in the surface sediments of phytoplankton-dominated zones was 372.38-529.64 mg·kg^-1, and that in macrophyte-dominated zones was 304.29-454.27 mg·kg^-1. In surface sediments, concentrations of TP in phytoplankton-dominated zones were significantly higher than in phytoplankton-dominated zones. The highest TP concentrations appeared in winter, and the lowest in summer. These were owing to the input of exogenous pollution, and the migration and transformation of internal phosphorus between sediments and overlying water under different environmental conditions. ③ The order of the mass fraction of phosphorus in sediments was:NH₄Cl-P < Fe-P < Org-P < Res-P < Al-P < Ca-P. Mobile-P=NH₄Cl-P+Fe-P+Org-P, accounting for 9.10%-16.93% of TP in phytoplankton-dominated zones, and slightly higher in macrophyte-dominated zones, where it was 8.11%-13.50%. Res-P accounted for 10.06%-14.97% of TP in phytoplankton-dominated zones, and 11.02%-20.28% in macrophyte-dominated zones. The risk of internal phosphorus release in phytoplankton-dominated zones is high, which is not conducive to the fixation and burial of phosphorus. The eutrophication degree of different regions in Taihu Lake is obviously different, and different characteristics of phosphorus release and burial are showed. The phytoplankton-dominated zones deserve special attention because of their high internal phosphorus load and release potential.

No association between alleles or genotypes at the dopamine transporter gene and schizophrenia

The dopamine transporter gene (DAT1) is an important candidate gene for schizophrenia. A 40-bp VNTR (variable number of tandem repeats) polymorphism of DAT1 has been typed in 105 schizophrenic patients and 98 normal control subjects from Sichuan (China). Compared with allele frequencies for Caucasians reported in the literature, the Chinese population investigated showed a reduced frequency of the 9-copy allele and an increased frequency of the 10-copy allele. The observed frequency of genotypes was in agreement with the expected values according to Hardy-Weinberg equilibrium. No significant difference was found between patients and control subjects with regard to allele frequency, allele prevalence, and genotype counts. The results of the association study presented here are in agreement with the negative results of linkage analyses in schizophrenia pedigrees from Iceland (Kristbjarnarson et al., submitted) and from Utah (Byerley et al., 1993). Taken together, these studies suggest that variation in the dopamine transporter gene (DAT1) is unlikely to be a factor in the etiology of schizophrenia. The observed differences in allele frequencies between Chinese and Caucasian groups suggest that the human transporter gene might be useful for the construction of evolutionary trees in humans and primates as illustrated by Cavalli-Sforza's work (Mountain et al., 1992).

No association between schizophrenia and homozygosity at the D3 dopamine receptor gene

The D3 dopamine receptor gene is an important candidate gene for schizophrenia, since (because of its almost exclusive expression in the limbic system) it combines the dopamine receptor hypothesis with the limbic system hypothesis of schizophrenia. A BalI restriction fragment length polymorphism of the D3 dopamine receptor gene has been typed in 107 schizophrenic patients and 98 normal controls from Sichuan (China). With regard to alleles or genotypes, no significant differences were obtained between controls from Europe and China, between patients and controls, and between patient subgroups and controls. These results indicate a lack of association between schizophrenia and the D3 dopamine receptor gene in our sample. Our findings are at variance with reports of a significant excess of homozygosity at the D3 dopamine receptor gene in schizophrenic patients from Wales (United Kingdom) and Alsace (France). In conclusion, further studies will be needed with larger samples of patients from Wales and Alsace as well as with samples of different racial groups to prove or disprove the initial positive association between schizophrenia and genotypes of the D3 dopamine receptor gene.

[Study on the peptides of serum and gastric juice in patients with gastric cancer]

This investigation, conducted on 35 patients with advanced-stage gastric cancer, included 28 men and 7 women with a mean age of 50.1 years; also studied were 33 normal subjects as controls: 26 men and 7 women with a mean age of 45.8 years. Samples of blood and gastric juice were collected at fasting and in gastroscopy respectively. Substance P (SP), beta-endorphin (beta-EP), vasoactive intestinal peptide (VIP), motilin (MTL), gastrin (GT), and leu-enkephalin (LEK) of the sera and gastric juices were measured by radioimmunoassay kits. In the patients, SP and beta-EP of serum and gastric juice, and VIP, MTL and LEK of gastric juice, were higher than in the normal subjects (p < 0.01); gastrin of serum and gastric juice were decreased (p < 0.01). Serum and gastric juice SP, beta-EP levels correlated negatively with the gastrin (r = 0.462-0.519, p < 0.05). These data support the assumption that study of the peptides of serum and gastric juice can show a clinically significant change in gastric cancer patients.

[Circadian changes of atrial natriuretic peptide, cyclic AMP, cyclic GMP, sodium, blood pressure and heart rate in normal subjects]

To investigate the circadian change in the plasma atrial natriuretic peptide (ANP) concentrations and its relation to cyclic AMP (cAMP), cyclic GMP (cGMP) and serum sodium. This investigation was conducted on 22 normal subjects consisting of 16 men and 6 women with a mean age of 21.5 years. Blood samples, systolic blood pressure (SBP), and heart rate (HR), were collected and recorded every 8 hours during a 24 hour period. SBP and HR were highest at 1600 h (p less than 0.05). Plasma ANP concentrations at 0800 h (196.3 +/- 140.6 ng/L, p less than 0.01) and 1600 h (203.4 +/- 127.5 ng/L, p less than 0.01) were higher than at 2400 h (64.4 +/- 46.0 ng/L). Serum sodium, plasma cAMP, and cGMP were at the highest level at 1600 h (p less than 0.05). Plasma ANP correlated with plasma cAMP, cGMP, serum sodium, SBP, and HR (r = 0.378 - 0.419, p less than 0.05). This data supports the assumption that atrial wall distension seems to be a stimulus for ANP release.

[Effect of capsaicin on the release of substance P from spinal cord and blood pressure]

The role of substance P (SP) in the regulation of sympathetic outflow to the cardiovascular system was assessed. Intrathecal injection(ith) of capsaicin caused a release of SP from the spinal cord and resulted in an increase in blood pressure and heart rate accompanied by an elevation of plasma adrenaline and noradrenaline. This pressor response was blocked by ith SP antagonist D-Pro2, D-Phe7, D-Trp9-SP or antiserum against SP. The immunohistochemical study showed that the SP-like immunoreactivity in T-8 of the spinal cord was decreased as the amount of capsaicin administrated was increased. Spinal cord transection had no effect on pressor responses caused by ith 10 micrograms capsaicin. These results suggest that SP transmits excitatory information to the cardiovascular system via spinal sympathetic pathway.

Cleavage furrow formation of Rana amurensis eggs observed with fluorescence pattern photobleaching

Taking advantage of the extremely slow lateral diffusion of proteins on Rana amurensis egg surface (Xu et al., 1984), it was possible to make a sharp concentric ring pattern on the egg surface by photobleaching of the fluorescein-labelled egg surface. The shape change of the pattern reveals the movement of the egg surface. The surface, even in front of the furrow tip, is drawn towards the furrow centre. The furrow tip differentiates into border and central lines as shown by the distribution of surface protrusions. Between the border and central lines the nascent membrane inserts while the width of furrow tip increases to nearly 100 microns.