Nitrification in natural waters with high suspended-solid content--a study for the Yellow River

In this research, the mechanism regarding the effects of suspended solids on nitrification in freshwater systems with high solid contents was examined. Experimental studies were conducted for natural water of the Yellow River under laboratory conditions. Nitrification kinetics was investigated in water systems with various levels of suspended-solid contents. The associated mechanisms were analyzed through investigation of the adsorption-desorption of ammonium nitrogen, the process of bacteria growth, and the feature of nitrification kinetics. The results indicated that the presence of suspended solids could accelerate the nitrification process. The nitrification rate would increase non-linearly with the increase of suspended-solid content. When the initial concentration of ammonia nitrogen was 12.70 mg/l in the water system, the ratios of half-time duration for nitrification would be 1.88:1.23:1 under suspended-solid contents of 0, 1.84 and 5.00 g/l, respectively. When the initial concentration of ammonia nitrogen was around 1.0 mg/l in the water system, the nitrification rates in systems with suspended-solid contents of 1.81 and 3.42 g/l would then be approximately 9 and 12 times that without suspended solids, respectively. The populations of nitrifying bacteria would rise with increasing suspended-solid content. The existence of suspended solids would increase the contact chances between bacteria and nitrogen, resulting in accelerated nitrification processes; this was manifested by the increased K(4) (tau(max)/K(S)) along with the raised suspended-solid contents while fitting nitrification kinetics with the growth-based logistic model. Since the amount of ammonium nitrogen adsorbed on suspended-solid surface was non-linearly proportional to the suspended-solid content, the nitrification rate was also non-linearly proportional to the suspended-solid content.

Materials selection for a dry atmospheric mercury deposits sampler

In order to develop a sampler for measuring dry deposition rates for atmospheric mercury, suitable materials are needed that neither adsorb nor release mercury. In this paper, four materials (polyvinyl chloride (PVC), acrylonitrile-butadiene-styrene (ABS), Teflon and glass) were tested. Each of the materials was placed in a beaker containing mercuric solution under varied conditions for pH, preservative concentration, initial mercuric concentration, temperature, acid type and contact time of the material. The concentrations of the mercuric solutions were determined using the cold-vapor atomic absorption (CVAA) technique. The experimental results show that glass has the lowest absolute net adsorption rates (NARs) of 0.026-1.13 pg/m2 among the materials tested. Teflon, PVC and ABS have NARs ranging from 0.54 to 10.4 microg/M2 over an adsorption duration of one or two weeks. ABS has significantly higher adsorption rates for mercury than PVC and Teflon, indicating its inappropriateness as the material for building the sampler. Teflon and PVC will be the materials of choice for the sampler. The experimental results can also be used in establishing appropriate sampling conditions in the field.

Additive noise properties of active matrix flat-panel imagers

A detailed theoretical and empirical investigation of additive noise for indirect detection, active matrix flat-panel imagers (AMFPIs) has been performed. Such imagers comprise a pixelated array, incorporating photodiodes and thin-film transistors (TFTs), and an associated electronic acquisition system. A theoretical model of additive noise, defined as the noise of an imaging system in the absence of radiation, has been developed. This model is based upon an equivalent-noise-circuit representation of an AMFPI. The model contains a number of uncorrelated noise components which have been designated as pixel noise, data line thermal noise, externally coupled noise, preamplifier noise and digitization noise. Pixel noise is further divided into the following components: TFT thermal noise, shot and 1/f noise associated with the TFT and photodiode leakage currents, and TFT transient noise. Measurements of various additive noise components were carried out on a prototype imaging system based on a 508 microm pitch, 26 x 26 cm2 array. Other measurements were performed in the absence of the array, involving discrete components connected to the preamplifier input. Overall, model predictions of total additive noise as well as of pixel, preamplifier, and data line thermal noise components were in agreement with results of their measured counterparts. For the imaging system examined, the model predicts that pixel noise is dominated by shot and 1/f noise components of the photodiode and TFT at frame times above approximately 1 s. As frame time decreases, pixel noise is increasingly dominated by TFT thermal noise. Under these conditions, the reasonable degree of agreement observed between measurements and model predictions provides strong evidence that the role of TFT thermal noise has been properly incorporated into the model. Finally, the role of the resistance and capacitance of array data lines in the model was investigated using discrete component circuits at the preamplifier input. Measurements of preamplifier noise and data line thermal noise components as a function of input capacitance and resistance were found to be in reasonable agreement with model predictions.

A quantitative investigation of additive noise reduction for active matrix flat-panel imagers using compensation lines

A quantitative investigation of a technique for reducing correlated noise in indirect detection active matrix flat-panel imagers has been reported. Correlated noise in such systems arises from the coupling of electronic noise, originating from fluctuations in external sources such as power supplies and ambient electromagnetic sources, to the imaging array via its address lines. The noise reduction technique involves the use of signals from columns of compensation line pixels located in relatively close proximity to the columns of normal imaging pixels on the array. Compensation line pixels are designed to be as sensitive to externally-coupled noise as columns of normal imaging pixels but are insensitive to incident radiation. For each imaging pixel, correlated noise is removed by subtracting from the imaging pixel signal a signal derived from compensation line pixels located on the same row. The effectiveness of various implementations of this correction has been examined through measurements of signal and noise from individual pixels as well as of noise power spectra. These measurements were performed both in the absence of radiation as well as with x rays. The effectiveness of the correction was also demonstrated qualitatively by means of an image of a hand phantom. It was found that the use of a single compensation line dramatically reduces external noise through removal of the correlated noise component. While this form of the correction increases non-radiation-related uncorrelated noise, the effect can be largely reduced through the introduction of multiple compensation lines. Finally, a position-dependent correction based on compensation lines on both sides of the array was found to be effective when the magnitude of the correlated noise varied linearly across the array.

[Study on inhibitory actions of san huang yi gan capsule (SHYGC) on HBeAg with seropharmacological method]

In this paper, the inhibitory actions of SHYGC on HBeAg in vitro were studied with the seropharmacological method. By Enzyme Linked Immuno Sorbent Assay (ELISA), it was found that the rabbit sera containing SHYGC have significant inhibitory effects on HBeAg, and they become stronger with the drug concentration in sera improved and the actions time prolonged, they decrease with the HBeAg concentration improved, and the effects of the sera containing hing-dose drugs equal those of Su Xiao Jing containing 250 micrograms/g effective chloric. The direct external inhibitory effects of SHYGC in original pharmaceutics are stronger than those of the sera containing drugs. It probably indicated that the active ingredients of SHYGC could not be digested and absorbed completely from gastrointestine, or were inactived by metabolism in vivo.

[Study on erzhi pill effects on neuro-endocrinologic-immuno network of animal of deficiency of yin]

OBJECTIVE

To investigate Erzhi Pill effect on Neuro-Endocrinologic-Immuno network of animal of deficiency of Yin.

METHOD

In the experiment through the determination of hemotic cortisol, insulin, testosterone, beta-endorphin, cholesterol, weight of adrenal and thymus, ConA-induced, spleelymphocyte proliferation and activity of natural killer cells (NKC). The changes of the animals of deficiency of Yin and the effects of the Erzhi Pill were investigated.

RESULT

It showed that rats of deficiency of Yin, their hemotic, cortisol, insulin, testosterone, beta-endorphin, weight of adrenal and thymus decreased, cholesterol increased and mouse of deficiency of Yin, their lymphocyte proliferation and activity of NKC dcreased, which might be modulated with Erzhi Pill. Erzhi Pill could improve hemotic cortisol, insulin, testosterone, beta-endorphin, weight of adrenal and thymus, reduce hemotic cholesterol, improve lymphocyte proliferation and activity of NKC.

CONCLUSION

This principle could improve animals of deficiency of Yin regulating Neuro-Endocrinologic-Immuno network and keeping homeostais.

Strategies to improve the signal and noise performance of active matrix, flat-panel imagers for diagnostic x-ray applications

A theoretical investigation of factors limiting the detective quantum efficiency (DQE) of active matrix flat-panel imagers (AMFPIs), and of methods to overcome these limitations, is reported. At the higher exposure levels associated with radiography, the present generation of AMFPIs is capable of exhibiting DQE performance equivalent, or superior, to that of existing film-screen and computed radiography systems. However, at exposure levels commonly encountered in fluoroscopy, AMFPIs exhibit significantly reduced DQE and this problem is accentuated at higher spatial frequencies. The problem applies both to AMFPIs that rely on indirect detection as well as direct detection of the incident radiation. This reduced performance derives from the relatively large magnitude of the square of the total additive noise compared to the system gain for existing AMFPIs. In order to circumvent these restrictions, a variety of strategies to decrease additive noise and enhance system gain are proposed. Additive noise could be reduced through improved preamplifier, pixel and array design, including the incorporation of compensation lines to sample external line noise. System gain could be enhanced through the use of continuous photodiodes, pixel amplifiers, or higher gain x-ray converters such as lead iodide. The feasibility of these and other strategies is discussed and potential improvements to DQE performance are quantified through a theoretical investigation of a variety of hypothetical 200 microm pitch designs. At low exposures, such improvements could greatly increase the magnitude of the low spatial frequency component of the DQE, rendering it practically independent of exposure while simultaneously reducing the falloff in DQE at higher spatial frequencies. Furthermore, such noise reduction and gain enhancement could lead to the development of AMFPIs with high DQE performance which are capable of providing both high resolution radiographic images, at approximately 100 microm pixel resolution, as well as variable resolution fluoroscopic images at 30 fps.

[Endothelial cell damage induced in vitro by subeschar tissue fluid]

OBJECTIVE

To assess the effect of subeschar tissue fluid (STF) on the function and structure of endothelial cell in vitro.

METHODS

Human umbilical vein endothelial cells (HUVEC) were incubated with STF obtained from patients in the early postburn stage. Then the morphological changes in EC were observed, and activity of EC and contents of LDH, 6-keto-PGF1 alpha in media were determined.

RESULTS

The activity of LDH and the content of 6-keto-PGF1 alpha were increased gradually after HUVEC incubated with STF, and were higher than that measured after HUVEC incubated with healthy volunteer's sera. Furthermore, activity of HUVEC decreased and they became deformed, showing shrinkage of the cell body with enlargement of intercellular space. In addition, small vacuoles appeared in cytoplasm with karyopyoknosis after 24 h.

CONCLUSION

STF can damage endothelial cell and might play an important role in the pathophysiological process of burn injury.

Inhibition of IgE-mediated triggering of mast cells by complement-derived peptides interacting with the Fc epsilon RI

Mucosal type mast cells, in contrast to the serosal type ones, do not respond to cationic agents, or to the complement-derived peptides C3a and C5a. Earlier we have found that while C3a does not activate the rat mucosal type mast cells (line RBL-2H3), it strongly inhibits the IgE-mediated triggering of these cells, by interfering with the Fc epsilon RI-initiated signaling pathway. In the present study we further investigated the mechanism of this process. It is shown, that C3a interacts with the beta-chain of the Fc epsilon RI complex. Binding of the complement peptide to the cells apparently causes a decrease in the proximity of the IgE-binding Fc epsilon RI. Investigating certain sequences of C3a we found that the inhibition is caused by the C-terminal sequences of the complement-peptide, ranging from positions 56 to 77 and also by a shorter sequence, ranging from positions 56 to 64. The inhibitory effect of these peptides was observed both in the case of RBL-2H3 cells and mouse bone marrow derived mast cells.

Serine-23 is a major protein kinase A phosphorylation site on the amino-terminal head domain of the middle molecular mass subunit of neurofilament proteins

We have shown previously that phosphate groups on the amino-terminal head domain region of the middle molecular mass subunit of neurofilament proteins (NF-M) are added by second messenger-dependent protein kinases. Here, we have identified Ser23 as a specific protein kinase A phosphorylation site on the native NF-M subunit and on two synthetic peptides, S1 (14RRVPTETRSSF24) and S2 (21RSSFSRVSGSPSSGFRSQSWS41), localized within the amino-terminal head domain region. Ser23 was identified as a phosphorylation site on the 32P-labeled alpha-chymotryptic peptide that carried >80% of the 32P-phosphates incorporated into the NF-M subunit by protein kinase A. The synthetic peptides S1 and S2 were phosphorylated 18 and two times more efficiently by protein kinase A than protein kinase C, respectively. Neither of the peptides was phosphorylated by casein kinase II. The sequence analyses of the chemically modified phosphorylated serine residues showed that Ser23 was the major site of phosphorylation for protein kinase A on both S1 and S2 peptides. Low levels of incorporation of 32P-phosphates into Ser22, Ser28, and Ser32 by protein kinase A were also observed. Protein kinase C incorporated 32P-phosphates into Ser22, Ser23, Ser25, Ser28, Ser32, and a threonine residue, but none of these sites could be assigned as a major site of phosphorylation. Analyses of the phosphorylated synthetic peptides by liquid chromatography-tandem mass spectrometry also showed that protein kinase A phosphorylated only one site on peptide S1 and that ions with up to four phosphates were detected on peptide S2. Analysis of the data from the tandem ion trap mass spectrometry by using the computer program PEPSEARCH did not unequivocally identify the specific sites of phosphorylation on these serine-rich peptides. Our data suggest that Ser23 is a major protein kinase A-specific phosphorylation site on the amino-terminal head region of the NF-M subunit. Phosphorylation of Ser23 on the NF-M subunit by protein kinase A may play a regulatory role in neurofilament assembly and/or the organization of neurofilaments in the axon.

Clustering the mast cell function-associated antigen (MAFA) induces tyrosyl phosphorylation of the Fc epsilonRI-beta subunit

The mast cell function associated antigen (MAFA) is a membranal glycoprotein identified on the surface membranes of rat mucosal-type mast cells of the RBL-2H3 line by a monoclonal antibody (G63) binding to it. MAFA clustering by mAb G63 causes a dose-dependent inhibition of these mast cells' response to immunological stimulus provided by the type 1 Fc epsilon receptor (Fc epsilonRI) suppressing the biochemical processes coupling it to mediator secretion. The inhibition was found to take place upstream to the production of inositol phosphates and the transient increase in free cytosolic Ca2+ ion concentration, hence it probably interferes with the cascade at the level of the protein tyrosyl kinases (PTK) activity. We have therefore examined whether MAFA clustering affects protein tyrosyl phosphorylation of cell components and found that a time-dependent increase is caused in this modification of the Fc epsilonRI-beta chain. This constitutes the first evidence for the capacity of the clustered MAFA to enhance, on its own, biochemical changes in the mast cells, changes that are most probably related to its inhibitory signaling capacity. Moreover, that the observed phosphorylation changes are in the Fc epsilonRI-beta chain clearly indicates possible cross-talk between these two membrane components.

[The relationship of non-Hodgkin's lymphoma with P16 protein expression]

The expression of P16 protein was examined in 45 cases of non-Hodgkin's lymphoma (NHL), 4 cases of reactive hyperplasia of lymph node (RHLN) and 6 cases of normal spleen with immunohistochemical staining. Positive reaction of P16 protein was observed in some lymphocytes of RHLN and splenic nodule and around splenic sinus. The positive rate of P16 protein expression in NHL was 37.8% (17/45). The positive rates of P16 protein expression for the low intermadiate- and high-grade malignancy groups were 66.7% (10/15), 37.5% (6/16) and 7.1% (1/14) respectively. There was a significant difference between the low malignancy NHL and the high malignancy NHL (P < 0.005) in expression rate of P16 protein. It suggests that P16 protein expression may be one of the important parameters in estimating the prognosis of patients with NHL.

A comparison of results for the University of Missouri Research Reactor radiological airborne release assessments obtained from PC-based computer programs

The United States Environmental Protection Agency has published three computer programs, COMPLY, AIRDOS-PC, and CAP88-PC, to assist the regulated community in determining compliance with the Environmental Protection Agency radionuclide air emission standards. The programs calculate radiation doses from routine airborne release to the general public residing outside a nuclear facility site. They consider doses from inhalation, ingestion of contaminated food, air immersion, and ground deposition. A PC-based computer code, XOQDOQ-82, developed for the Nuclear Regulatory Commission, was also chosen to compare and evaluate dispersion results from the Environmental Protection Agency codes for the University of Missouri Research Reactor Center. Effects of building parameters, terrain conditions, and downwind distances on dispersion factors were calculated. The results of this study indicated that dispersion factors calculated using AIRDOS-PC and CAP88-PC were several times lower than those calculated using XOQDOQ-82 at all distances, and those dispersion factors calculated using COMPLY were several times lower than the XOQDOQ-82 values at distances greater than 600 m.

Calcium channel blocker treatment of tumor cells induces alterations in the cytoskeleton, mobility of the integrin alpha IIb beta 3 and tumor-cell-induced platelet aggregation

Calcium channel blockers of the phenylalkylamine (i.e. verapamil), benzothiazepine (i.e. diltiazem) and dihydropyridine (i.e. nifedipine) classes were evaluated for effects on the tumor cell/platelet interactions using Walker 256 carcinosarcoma cells (W256 cells). When W256 cells were pretreated for 15 min with channel blockers at concentrations of 50-200 microM, macroscopic tumor-cell-induced platelet aggregation was inhibited (order of potency; nifedipine greater than diltiazem much greater than verapamil). However, ultrastructural analysis revealed limited, focal platelet aggregates associated with tumor cell plasma membranes of verapamil- and diltiazem-treated cells. There was no evidence of platelet activation or platelet association with the tumor cell membrane in cells pretreated with nifedipine. Walker 256 cells possess the intergrin alpha IIb beta 3. Tumor cell alpha IIb beta 3 was shown to mediate tumor cell/platelet interactions in vitro [Chopra et al. (1988) Cancer Res. 48:3787]. Patching and capping of surface alpha IIb beta 3 were inhibited by nifedipine greater than diltiazem much greater than verapamil. The degree of inhibition of alpha IIb beta 3 receptor mobility parallels the inhibition of tumor-cell-induced platelet aggregation. W256 cells are characterized by a well-developed microfilament and intermediate filament network and by the absence of a distinct microtubular network. Calcium channel blockers had no effect on the low polymerization level of tubulin. However, they induced rearrangement of microfilament stress fibers. Intermediate filaments were also rearranged but to varying degrees. The order of effectiveness for alteration of intermediate filament organization was nifedipine greater than diltiazem while verapamil was ineffective. We propose that the previously reported inhibition of tumor cell/platelet interaction and tumor cell metastasis by calcium channel blockers [Honn et al. (1984) Clin Exp Metastasis 1:61] is due not only to the effects of the Ca2+ channel blockers on platelets, but also to their effect on the tumor cell cytoskeleton resulting in an inhibition of the mobility and function of the alpha IIb beta 3 receptor.

Is there a role for the tumor cell integrin alpha IIb beta 3 and cytoskeleton in tumor cell-platelet interaction?

In vitro tumor cell-platelet interaction was examined using B16 amelanotic (B16a) melanoma cells. These tumor cells express the alpha IIb beta 3-type cytoadhesin. Aggregation studies demonstrated that tumor cell surface alpha IIb beta 3 mediates the recognition of platelets since pretreatment of tumor cells with antibody against alpha IIb beta 3 prevents platelet-tumor cell interaction as well as platelet activation measured by aggregometry, platelet eicosanoid metabolism and ultrastructural analysis. In B16a cells, disruption of the microfilaments and intermediate filaments inhibits mobility of alpha IIb beta 3 on the cell surface. Microtubules do not play a role in receptor mobility, because B16a cells do not possess well-defined microtubules in interphase and colchicine does not affect receptor mobility. Disruption of microfilaments or intermediate filaments results in an inhibition of tumor cell-platelet interaction as evidenced by aggregometry studies and ultrastructural analysis. We suggest that platelet interaction with tumor cells begins with alpha IIb beta 3-mediated receptor recognition followed by not only platelet activation but also microfilament- and vimentin intermediate filament-dependent tumor cell activation.