X52管线钢抗硫化氢应力腐蚀实验分析

介绍X52管线钢的抗硫化氢应力腐蚀实验。根据NACE 0284—2003和NACE TM 0177—2005,采用氢致开裂(HIC)实验,硫化物应力腐蚀(SSC-A,SSC-四点弯曲法)实验和电化学测试,检测X52管线钢的抗硫化氢应力腐蚀(SSC)开裂能力。将X52管线钢经过96 h的氢致开裂实验,加载比例分别为最小屈服强度的80%,85%,90%的SSC-A实验和SSC-四点弯曲实验720 h,均未发现裂纹。结果表明,X52管线钢具有较好的抗硫化氢应力腐蚀能力。     

The role of calcium, phosphate and citrate ions in the stabilization of casein micelles.

To obtain greater insight into the interaction of Ca, citrate and phosphate ions with casein, 31PNMR measurements were performed on combinations of these ions with alphas- and kappa-caseins. It was found that addition of alphas-casein to a Ca phosphate solution in D2O at 27 degrees C and pD 6.4 resulted in a downfield shift of the 31P singlet. An almost identical shift was observed with kappa-casein, but no shift was found when only phosphate ions were present or when Ca2+ were added to phosphate ions in the absence of casein. Separate experiments with poly-L-lysine, mol. wt approx. 35,000, resulted in similar downfield 31P chemical shifts of Ca phosphate as with both caseins, whereas no shift was observed when poly-glycine was added. From these results it can be concluded that Ca and phosphate ions associate with casein in a co-operative manner, probably in the way described by ter Horst (1963) as a complex with the NH3+-groups of lysine or arginine in a structure such as: (casein--NH3+)--PO43---Ca2+. The formation of this complex may be enhanced by citrate ions, since preliminary results have shown that addition of Na citrate to a solution of alphas-casein with added Ca phosphate produces a broadening of the 31P signal as well as a chemical shift.     

2,4-D sorption in iron oxide-rich soils: role of soil phosphate and exchangeable Al

This study examined herbicide retention in iron oxide-rich variable charge soils (Ultisols) under no cultivation (forest), agriculture (farm), and turf maintenance (golf course) to explore the following hypothesis: inorganic phosphate accumulation from soil fertilization and liming to decrease exchangeable aluminum (Al) content will influence carboxylic acid herbicide sorption onto soils and leaching into groundwater. A suite of soil properties, including mineralogy (particularly soil iron and aluminum oxide content), exchangeable Al content, and soil phosphate content, influenced sorption of the anionic, 2,4-D. In general, 2,4-D sorption was lower in the presence of phosphate, possibly due to competition between phosphate and 2,4-D for surface sites or increase in surface negative charge resulting from phosphate sorption. Additionally, 2,4-D sorption was greater in the presence of exchangeable Al. It appears that 2,4-D may form surface complexes with or be electrostatically attracted to exchangeable aluminum in the soil. Our results suggest that carboxylic acid herbicides may be more easily leached in intensively managed Ultisols subject to continued phosphate fertilization and liming.     

Effects of pithing on pH, creatine phosphate and ATP-related compounds of beef Psoas major and Longissimus dorsi muscles

The effects of pithing at slaughter on meat quality were studied in M. longissimus dorsi (LD muscle) and M. psoas major (PM muscle) from steers. Ten steers, half of them pithed and the others not pithed at slaughter, were used for determining pH values and concentrations of creatine phosphate (CP), adenosine triphosphate (ATP) and its breakdown products in the muscles at 2·0 h post mortem. CP was not detected in any PM muscles from pithed steers and no significant differences were observed between pithed and non-pithed steers on the mean values of pH and any compounds, but significant differences were observed in the variance of pH value, ATP, (inosine monophosphate IMP) and inosine levels in PM muscles and of (adenosine diphosphate ADP) and IMP levels in LD muscles. When two steers with excitable temperament were excluded from the pithed group significant differences of variance between the treatments were observed only in PM muscles. The pithing procedure thus affects the levels of pH and of some of the ATP-related compounds in the PM but not in LD muscles.     

Effects of pH and phosphate status of a silty clay loam on manganese,zinc and copper concentrations in soil fractions and in clover

The field pH of a silty clay loam soil affected manganese, zinc and copper concentrations in the fraction extracted by DTPA; lower pH soils had higher metal concentrations. The soil pH also affected manganese and zinc but not copper concentrations in the soil solution, and in shoots of clover grown in pots. Metal concentrations in soil fractions were not affected by soil phosphate status, but zinc and copper concentrations in clover shoots were significantly lower when plants were grown on soils of high phosphate status. Manganese and zinc levels in shoots were predicted slightly more accurately by using soil solution data than by using concentrations extracted by DTPA.     

The effect of phosphate, sodium chloride, sodium nitrite, storage temperature and pH on the growth of enteropathogenic Escherichia coli in a laboratory medium

The effect of eight phosphates in combination with sodium chloride/nitrite mixtures on growth of mixed strains of enteropathogenic Escherichia coli over a period of 10 weeks at three pH values (5.6, 6.2, 6.8) and at seven temperatures ranging from 10 degrees C to 35 degrees C is reported. All eight phosphates inhibited growth to varying degrees in at least some of the conditions investigated. Instances of inhibition increased with concentration of sodium chloride/nitrite and were more frequent at lower temperatures and pH values.     

Effects of pH and sodium ions on NaHCO3 extractable phosphate in calcareous/sodic soils

One calcareous and one sodic soil were treated with solutions of either sodium carbonate (Na₂CO₃) or sodium perchlorate (NaCIO₄) to increase their sodium (Na) saturation before extracting with sodium bicarbonate (NaHCO₃) to measure the recovery of native plus added phosphate (P). The Na₂CO₃ additions also increased pH, and by comparing with the NaCIO₄ treatments, it was possible to separate the effects of added Na and pH on extractable P. For the calcareous soil both added Na and increased pH led to increases in the amount of NaHCO₃-extractable P. For the sodic soil the amount of extractable P was mainly affected by pH, with little, if any, effect of the added Na. The suitability of the Olsen test for soil P for Na-affected soils is discussed.     

Oxygen isotopes unravel the role of microorganisms in phosphate cycling in soils

Phosphorus (P) is considered the ultimate limiting nutrient for plants in most natural systems and changes in the distribution of inorganic and organic P forms during soil development have been well documented. In particular, microbial activity has been shown to be an important control on P cycling but its contribution in building up the pool of plant-available P during soil development is still poorly quantified. To determine the importance of different biological processes on P cycling, we analyzed the isotopic composition of oxygen in phosphate (δ(18)O-Pi) from the parent material, soil microorganisms, the available P pool, and from the vegetation along a 150-year soil chronosequence of a glacier forefield. Our results show that at all sites, δ(18)O-Pi of microbial Pi is within the range expected for the temperature-dependent equilibrium between phosphate and water. In addition, the isotopic signature of available Pi is close to the signature of microbial Pi, independently of the contribution of parent material Pi, vegetation Pi or Pi released from organic matter mineralization. Thus, we show that phosphate is cycled through soil microorganisms before being released to the available pool. This isotopic approach demonstrates for the first time in the field and over long time scales, and not only through controlled experiments, the role of the microbial activity in cycling of P in soils.     

Sorption of three tetracyclines by several soils: assessing the role of pH and cation exchange

Tetracyclines (TCs) are widely used in veterinary medicine for treatment and prevention of disease and are present in animal waste products. Detection of TCs in soil, sediments, and water, and the growing concern of their potentially adverse effect on natural ecosystems have resulted in a need to understand their behavior in aqueous soil systems. TCs have multiple ionizable functional groups such that at environmentally relevant pH values, they may exist as a cation (+ 0 0), zwitterion (+ - 0), or a net negatively charged ion (+ - -), which complicates predicting their sorption, availability, and transport. We investigated the sorption of oxytetracycline (OTC), tetracycline (TC), and chlortetracycline (CTC) by several soils varying in pH, clay amount and type, cation exchange capacity (CEC), anion exchange capacity (AEC), and soil organic carbon in 0.01 N CaCl2, 0.001 N CaCl2, and 0.01 N KCI. All three TCs are highly sorbed, especially in acidic and high clay soils. When normalized to CEC, sorption tends to decrease with increasing pH. A sorption model in which species-specific sorption coefficients normalized to pH-dependent CEC (Kd+00, kd+-0, and kd+--) and weighted by the pH-dependent fraction of each species fit the data well across all soils except for a soil rich in gibbsite and high in AEC. Resulting kd+00 values were more than an order of magnitude larger than values for either kd+0 and kd+--values such that kd+00 alone described most of the sorption observed as a function of pH for eight soils that varied in their mineralogy and pH (pH ranged from 4 to 8).     

Effects of pre-rigor injection of sodium citrate or acetate, or post-rigor injection of phosphate plus salt on post-mortem glycolysis, pH, and pork quality attributes

Forty pork carcass sides were assigned to one of four treatments: pre-rigor citrate (CIT) or acetate injection (ACE); post-rigor phosphate and salt injection (PHOS); and non-injected control (CON). Loins in 20 sides were injected at 50 min post-mortem with 4% solutions of CIT or ACE to approximately 110% of projected loin weights, and 10 loins were injected at 24 h post-mortem to 106.6% with a solution of 4.4% PHOS and 2.2% salt. Although CIT increased pH (P < 0.05), neither CIT nor ACE altered (P > 0.05) glycolytic metabolite concentrations. The pH increase in muscles from the CIT treatment was most likely due to its buffering ability rather than to its glycolytic inhibition. Pre-rigor CIT injection improved tenderness without the detrimental effects on color or flavor found with PHOS, but neither CIT nor ACE altered glycolytic metabolites or improved firmness, wetness, or fresh visual color over CON. Poor flavor attributes of the ACE treatment will hinder its use as an ingredient for pork enhancement solutions.     

Reduction of acrolein by elemental iron: kinetics, pH effect, and detoxification

Acrolein is a highly toxic alpha,beta-unsaturated aldehyde that is widely used as a biocide, a cross-linking agent, and an intermediate in the chemical industry, among other applications. In this study we investigated the reductive transformation of acrolein by elemental iron and evaluated the feasibility of using iron to detoxify acrolein. At acidic and neutral pH, acrolein was transformed by iron through reduction of the C=C double bond to propionaldehyde. The reduction appeared to involve the chemisorption of acrolein to the iron surface followed by reduction of adsorbed acrolein. Both the adsorption and reduction rate constants decreased with increasing pH. Between pH 7.0 and 7.4, the acrolein adsorption rate constant decreased precipitously, resulting in a sharp decline in its removal rate. At higher pH, acrolein disappeared rapidly in control without iron, presumably due to reversible, base-catalyzed hydration. At equilibrium, approximately 93% of acrolein was hydrated, corresponding to an equilibrium constant of 13. Acrolein at 25 mg/L completely inhibited aerobic respiration; in contrast, its reduction product propionaldehyde was biodegradable. This suggests that elemental iron may be used to pretreat acrolein-containing wastes prior to aerobic biodegradation. To our knowledge, this is the first report of reduction and detoxification of an alpha,beta-unsaturated aldehyde by elemental iron.     

Cr(VI) reduction and immobilization by magnetite under alkaline pH conditions: the role of passivation

This study investigated Cr(VI) reduction and immobilization by magnetite under alkaline pH conditions similar to those present at the Hanford site. Compared to acidic and neutral pH, chromium(VI) reduction by magnetite at high pH conditions is limited (<20% of potential reduction capacity), and the extent of reduction does not vary significantly with increasing NaOH concentration. This is due to the formation of maghemite, goethite, and/or Fe1-xCrxOOH, which may form a passivation layer on the magnetite surface, stopping further chromate reduction. Maghemite is formed in lower NaOH concentrations. The extent of goethite formation increases with NaOH concentration. Goethite may be formed through two mechanisms: (i) dissolution of magnetite leads to the precipitation of goethite and/or (ii) dissolution of newly formed maghemite intermediate, followed by precipitation of goethite. Extended X-ray absorption fine structure spectroscopy shows that Cr has a similar structural environment at alkaline pH as at acidic and circumneutral conditions.     

pH dependence of Fenton reagent generation and As(III) oxidation and removal by corrosion of zero valent iron in aerated water

Corrosion of zerovalent iron (ZVI) in oxygen-containing water produces reactive intermediates that can oxidize various organic and inorganic compounds. We investigated the kinetics and mechanism of Fenton reagent generation and As(III) oxidation and removal by ZVI (0.1m2/g) from pH 3-11 in aerated water. Observed half-lives for the oxidation of initially 500 microg/L As(III) by 150 mg Fe(0)/L were 26-80 min at pH 3-9. At pH 11, no As(III) oxidation was observed during the first two hours. Dissolved Fe(III) reached 325, 140, and 6 microM at pH 3, 5, and 7. H2O2 concentrations peaked within 10 min at 1.2, 0.4, and < 0.1 microM at pH 3, 5, and 7, and then decreased to undetectable levels. Addition of 2,2'-bipyridine (1-3 mM), prevented Fe(II) oxidation by O2 and H2O2 and inhibited As(III)oxidation. 2-propanol (14 mM), scavenging OH-radicals, quenched the As(III) oxidation at pH 3, but had almost no effect at pH 5 and 7. Experimental data and kinetic modeling suggest that As(III) was oxidized mainly in solution by the Fenton reaction and removed by sorption on newly formed hydrous ferric oxides. OH-radials are the main oxidant for As(III) at low pH, whereas a more selective oxidant oxidizes As(III) at circumneutral pH.     

Cottonseed Proteins in Frankfurters: Effect on pH, Cured Color, and Sensory and Physical Properties

Frankfurter-type sausages were made in which 5%, 10%, or 15% of the meat was replaced with the following cottonseed-derived protein products: genetically glandless cottonseed flour (CF); liquid cyclone processed deglanded cottonseed flour (LCPC); genetically glandless cottonseed storage protein isolate (CI). All-meat controls (0% cottonseed protein additive) were formulated at each replacement level with fat contents equivalent to those of the cottonseed protein-added frankfurters. Compared to all-meat controls, frankfurters made with increasing levels of cottonseed proteins generally had higher pH values, less cured color, less firmness of skin, softer texture, and were less desirable as judged by sensory panels. At the 10% and 15% replacement levels, frankfurters containing LCPC, had significantly (P < 0.05) lower scores for external and internal visual color, overall satisfaction and bioyield and rupture force values than did Cl-added frankfurters. Simple correlation coefficients suggest that significantly (P < 0.05) correlated responses exist within and across replacement levels between pH and sensory panel scores, Instron values and visual color scores.     

Superficial Charge Density of Fining Agents: Influence of pH,Dose, and Temperature

The effects of pH, dose, and temperature on the superficial charge density of fining agents were determined in a model solution. This study included three gelatines and one egg's albumin, all of which are common fining agents, as well as three wheat glutens (one native and two hydrolyzed). Wheat glutens have been allowed to be used as fining agents only since 2005, and there are no preliminary studies examining them. The results of this study showed that the superficial charge density was mainly pH-dependent (p < 0.01), and that pH showed a greater effect at a higher degree of protein hydrolysis. For Gel 3, albumin and the wheat glutens, a larger protein concentration, decreased the superficial charge density. Gel 2, which was soluble in hot water, had the highest superficial charge density (>0.831 meq g^?1), which indicated that it would be more reactive than the other fining agents. Between pH 3.4 and 4.0, Gluten 1 and Gel 3 were more highly charged (superficial charge density >0.3 meq g^?1) than Gel 1 or the hydrolysed glutens. These data are useful for wine producers.     

Softening Rates of Fermented Cucumber Tissue: Effects of pH, Calcium, and Temperature

First-order softening rates for cucumber mesocarp tissue were determined as a function of pH (2.6–3.8), calcium (0–72 mM), and temperature (25–65°C). Fermented tissue, unlike blanched, nonfermented tissue, often showed two softening rates in first-order plots. A five–variable, empirical equation was derived (R²= 0.913) which predicted softening rates as a tunction of pH, calcium concentration, and temperature. Comparison of softening rates in tissue fermented with and without 18 mM added calcium indicated the softening rate depended upon the concentration of calcium present during the period of measurement and not upon previous history of calcium exposure.     

Mastitis: effect of pH, temperature, and emollients on disinfecting action of N,N-dimethyldodecanamine

Growth inhibition of bacteria over time by N,N-dimethyldodecanamine, a tertiary alkyl amine, was studied to evaluate disinfecting action with changes in pH and temperature and with addition of emollients. Because alkyl amines have limited solubility in aqueous solutions, the effect of pH on solubility of the tertiary amine was determined. Non-growing cultures of Streptococcus agalactiae or Escherichia coli were added to sterile buffer or buffer containing the amine, and at specific intervals aliquots were removed, neutralized in a lecithin/Tween 80 quencher, and then plated to determine the number of surviving bacteria per plate. Survival curves were used to determine the effect of changing environmental conditions on antimicrobial activity. Antimicrobial activity was greater at pH 7 than at pH 8 and was least at pH 6. Increases in temperature from 20 to 40 degrees C caused a corresponding increase in antimicrobial activity. Addition of up to 10% glycerin or propylene glycol caused no significant decrease in antimicrobial activity of the tertiary amine.     

Acidity in upland and hill soils: Cation exchange capacity,pH and lime requirement

For 30 acid upland and hill soils, with initial pH from 3.5 to 5.8, and loss on ignition from 14% to 94%, cation exchange capacity varied with pH according to the relationship CEC = m pH+C, where m and C are characteristic of each soil. The slope m depended on loss on ignition (LOI), and is given by: m=Δ CEC/Δ=0.22 LOI+1.92. Because of these relationships, CEC measured at the natural pH of the soil (in 0.025 M MgSO₄ solution) is more relevant to field conditions than a conventional measurement at pH7. An improved method for estimating lime requirement (LR) of these soils was developed, based on the relationship found between LR and the difference in CEC (ΔCEC) between that at the natural pH of the soil and that at the target pH of 5.5: LR=1.12 ΔCEC+1.48. Lime requirement can therefore also be estimated from loss on ignition using the earlier relationships, and is given by: LR=(0.25 LOI+2.15) Δ+1.48, where Δ is the difference between the natural pH (in 0.025 M MgSO₄) and the target pH. Predictions based on this agreed well with results for a further 10 soils.     

Mortality and life expectancy in relation to long-term cigarette, cigar and pipe smoking: the Zutphen Study

Study objective

To study the effect of long‐term smoking on all‐cause and cause‐specific mortality, and to estimate the effects of cigarette and cigar or pipe smoking on life expectancy.

Design

A long‐term prospective cohort study.

Setting

Zutphen, The Netherlands.

Participants

1373 men from the Zutphen Study, born between 1900 and 1920 and studied between 1960 and 2000.

Measurements

Hazard ratios for the type of smoking, amount and duration of cigarette smoking, obtained from a time‐dependent Cox regression model. Absolute health effects of smoking are expressed as differences in life expectancy and the number of disease‐free years of life.

Main results

Duration of cigarette smoking was strongly associated with mortality from cardiovascular disease, lung cancer and chronic obstructive pulmonary disease, whereas both the number of cigarettes smoked as well as duration of cigarette smoking were strongly associated with all‐cause mortality. Average cigarette smoking reduced the total life expectancy by 6.8 years, whereas heavy cigarette smoking reduced the total life expectancy by 8.8 years. The number of total life‐years lost due to cigar or pipe smoking was 4.7 years. Moreover, cigarette smoking reduced the number of disease‐free life‐years by 5.8 years, and cigar or pipe smoking by 5.2 years. Stopping cigarette smoking at age 40 increased the life expectancy by 4.6 years, while the number of disease‐free life‐years was increased by 3.0 years.

Conclusions

Cigar or pipe smoking reduces life expectancy to a lesser extent than cigarette smoking. Both the number of cigarettes smoked and duration of smoking are strongly associated with mortality risk and the number of life‐years lost. Stopping smoking after age 40 has major health benefits.Smoking has been recognised as a health hazard for many years. Smoking causes a wide range of diseases, including cancer, chronic obstructive pulmonary disease (COPD) and cardiovascular diseases (CVD), and smoking cessation has impressive health benefits.^1,2,3 Cigarette smoking cessation decreases the risk of diseases and also increases life expectancy. Even stopping at age 60 gains about 3 years of life expectancy.⁴ Much less is known about the adverse effects of long‐term cigar or pipe smoking.^5,6,7Smoking has both long‐ and short‐term effects. As smoking habits change during life, information on long‐term smoking history is required to obtain correct estimates of the long‐term health effects of smoking. Because in most studies the level of detail on smoking history is limited, the impact of various aspects of the smoking history remains unclear. Leffondré et al⁸ show the importance of information on smoking duration, intensity and time since cessation in this respect. Although smoking duration has been associated with mortality before, most studies focused on cancer mortality rather than on CVD and COPD mortality.^{9,10,11,12,13,14,15}In epidemiological studies, hazard ratios are commonly used to express the impact on mortality. Hazard ratios express effects for one exposure group relative to the effect of the unexposed group—that is, the reference group—but do not give information regarding absolute public health effects. Therefore, life expectancies should be calculated. Although concepts like life expectancy are more informative and readily grasped by all, they are not reported frequently.The objective of this study is to assess the relationships between long‐term cigarette, cigar or pipe smoking, and duration and the number of cigarettes smoked, and mortality. To obtain accurate effect estimates, we used repeated measures of smoking habits collected in a 40‐year period and adjusted for potential confounders. In addition to hazard ratios, we present our results also in terms of changes in life expectancy at age 40 and the number of disease‐free years of life due to cigarette and cigar or pipe smoking.