液态树脂在管道修复中的应用

介绍了液态树脂修复材料的特性,以及管道修复程序,包括去除旧涂层,采用高压水冲洗技术设备对管道进行必要的维修或更换、表面处理准备等工作程序,并结合液态树脂修复材料在美国和哈萨克斯坦等国的应用实例,说明了该涂料的显著特点.     

Effect of age on immune parameters and the immune response of dogs to vaccines: a cross-sectional study

The evaluation of anti-aging intervention strategies in dogs would benefit from reliable quantitative biomarkers of aging. In the present study, the expression of various immune parameters was measured in young and old dogs to identify potential biomarkers of aging. The second goal of the study was to determine the effect of age on the immune response to vaccines. The immune function, including the antibody response to vaccines, was determined in 32 young adult (3.15+/-0.8 years of age) and 33 old dogs (12.1+/-1.3 years of age) of various breeds. Old dogs had a significantly lower lymphocyte proliferative response and a lower percentage of CD4+ T cells and CD45R+/CD4+ T cells, and a higher percentage of CD8+ T cells and a higher concentration of serum and salivary IgA. The most significant differences (P<0.001) occurred in the lymphocyte proliferative responses to ConA and PHA, the CD4:CD8 ratio, and the percentage of CD45R+/CD4+ T cells suggesting that these parameters are potential biomarkers of aging. There was no difference in the percentage of total T and B lymphocytes and the concentration of serum IgM and IgG. Both groups of dogs had protective titers against distemper virus, parvovirus and rabies virus before annual revaccination. The pre-vaccination titer against rabies virus was higher in the old dogs than in the young dogs, and there were no differences in post-vaccination titers against any of the viruses. This suggests that annual vaccination protocols provide adequate protection for old dogs.     

A review of phosphate oxygen isotope values in global bedrocks: Characterising a critical endmember to the soil phosphorus system

Understanding the phosphate oxygen isotope (δ¹⁸O‐PO₄) composition of bedrock phosphate sources is becoming ever more important, especially in areas of soil research which use this isotope signature as a proxy for biological cycling of phosphorus (P). For many of these studies, obtaining a sample of the source bedrock or applied mineral fertiliser for isotope analysis is impossible; meaning there is now a demand for a comprehensive characterisation of global bedrock δ¹⁸O‐PO₄ to support this work. Here we compile δ¹⁸O‐PO₄ data from a wide range of global bedrocks, including 56 new values produced as part of this study and a comprehensive overview of those within the previously existing literature. We present δ¹⁸O‐PO₄ data from the range of major phosphatic lithologies alongside as much metadata for the samples as could be gathered. Much of the data comes from bedrocks of marine sedimentary origin (< 1 Ma = > +22‰, > 540 Ma = ≈ +12‰), but we also present data from bedrocks associated with guano (range: +19.5 to +15‰) and igneous deposits (range: +12 to –0.8‰), both of which have distinct δ¹⁸O‐PO₄ signatures due to their formation mechanisms. We show that where repeat measurements of the same formation have been undertaken, regardless of method or exact sample location, there is an average within formation error of ± 1.25‰. This is important, as is constitutes a reasonable level of uncertainty for phosphorus cycling studies which need to estimate bedrock δ¹⁸O‐PO₄ composition based on the literature. In combination, this data set presents 284 δ¹⁸O‐PO₄ values from 56 countries; a comprehensive starting point for researchers interested in understanding bedrock end member δ¹⁸O‐PO₄.     

Metamorphosis in summer flounder: manipulation of rearing salinity to synchronize settling behavior, growth and development

In the aquaculture of summer flounder (Paralichthys dentatus), the inherent variation in growth and settling behavior during metamorphosis may lead to cannibalism and necessitate increased labor due to size grading. Our goal was to use an environmental salinity change as a cue to synchronize settling behavior and produce a larger, more uniformly sized cohort of juvenile summer flounder. Early metamorphic flounder were exposed to either a 5-day fluctuating (30–20–30–20–30 ppt; “Flux”) or a single (30–20 ppt; “20 ppt”) drop in rearing salinity. A control (continuous 30 ppt) was used for comparison. Average values for a peak settlement interval (PSI; defined as the interval beginning on the day by which the first 20% had settled until the day 80% had settled) were not affected by salinity manipulation, though the 20-ppt treatment did significantly increase percent settled per day by 54 dah. Average fish size was increased by the 20-ppt treatment (19.3±0.5 mm), but not the flux treatment (17.2±0.4 mm), compared to the control (17.6±0.5 mm). Developmental stage was significantly increased in the 20-ppt treatment (3.2±0.1) in comparison to the Flux (2.9±0.1), but not the control (3.1±0.1). However, the 20-ppt treatment reduced variance in development. To confirm the positive effects of the 20-ppt treatment, a second experiment was performed. A single salinity drop (“20 ppt”), a previously successful ([Gavlik, S., Albino, M., Specker, J.L., 2002. Metamorphosis in summer flounder: Manipulation of thyoid status to synchronize settling behavior, growth, and development. Aquaculture 203 (3-4), 359-373]thyroid hormone manipulation treatment (“TH”) and a combination of the two (“TH+20 ppt”) were compared to a control (continuous 30 ppt, no thyroid manipulation). The mean PSI was significantly reduced by both TH (7±1 days) and TH+20 ppt (8±0 days) treatments, compared to the control (11±1 days). The PSI for the 20-ppt treatment (9±0 days) was not significantly different than the control. The percent flounder settled per day was significantly increased by 20 ppt salinity and significantly modified (decreased, then increased) by TH manipulation. Flounder exposed to 20-ppt salinity were both larger (20 ppt: 18.6±0.3 mm; TH+20 ppt: 18.3±0.3 mm) and more developmentally advanced (20 ppt: 3.1±0.04; TH+20 ppt: 3.2±0.03) than flounder in 30 ppt (TH: 17.8±0.3 mm/3.1±0.3; Control: 17.9±0.3 mm/3.0±0.05). Finally, 20-ppt treatment reduced variance in development, while TH treatment reduced variance in both growth and development. Percent survival was unaffected by treatment in both experiments. In summary, a decrease in rearing salinity, from 30 to 20 ppt, increased growth, settling behavior and development of metamorphosing summer flounder. A decrease in rearing salinity, in combination with a TH manipulation, should result in larger, more uniformly sized flounder cohorts. We expect this synchronization will reduce the cannibalism and labor costs associated with size grading of cultured, metamorphosing summer flounder.     

An estimate of the dietary calcium requirement of fingerling Tilapia aurea reared in calcium-free water

Seven isocaloric and isonitrogenous semi-purified diets which contained graded levels of calcium ranging from 0.17 to 3.20% were fed to fingerling Tilapia aurea for a period of 11 weeks. The fish were maintained in a flow-through aquarium system supplied with calcium-free well water. Growth, feed conversion and bone composition data indicated that between 0.17 and 0.65% dietary calcium was adequate for optimum growth and normal bone mineralization.     

The effect of size on the response of Pacific oysters (<Emphasis Type="Italic">Crassostrea gigas</Emphasis>) to changes in water temperature and air exposure

To further improve the technology used in Pacific oyster farming, information is required on the response of different sized and aged oysters to various environmental changes. In this study a neutral red retention (NRR) assay was used to investigate the effects of size and age on the response of Pacific oysters to changes in water temperature and their recovery after exposure to different air temperatures. Results from moving oysters directly between water temperatures of 5°C and 15°C, 10°C and 20°C and 15°C and 25°C demonstrated that different water temperature change affect the lysosomal membrane integrity differently. The NRR times of large and small oysters transferred directly between 10°C and 20°C initially decreased significantly, and then increased to levels corresponding to the new temperature. In addition, NRR times in large oysters responded at a significantly slower rate than small oysters when they were transferred from 5°C and 25°C to 15°C water and between 10°C and 20°C water. Results from the air exposure experiments showed that, after exposure to air temperatures of 5°C, 15°C or 25°C, the lysosomal membrane integrity of large oysters recovered at a slower rate in 15°C water compared to small oysters. It therefore appears necessary to develop different management strategies for large (old) and small (young) oysters. Results from this and previous research also indicate that the NRR assay could potentially be used to develop a model to monitor and predict the performance of oysters on farms.     

Induced meiotic gynogenesis in shovelnose sturgeon

Gynogenesis was induced in three shovelnose sturgeon (Scaphirhynchus pIatorynchus) by heat shock after egg activation with UV-treated paddlefish (Polyodon spathula) milt. Ultraviolet dosage (J m–2) for the pooled milt samples was calculated using the following linear regression equation: Dosage = 2405.27 – 352.80X 19.78X2 (X = percent transmittance of milt). Activated eggs were incubated at 18 °C until shocking at 35 °C. Shock duration was applied at 0.050 intervals from 0.15 to 0.40 0 (8.25 to 22.00 min post-fertilization; 0 at 18 °C = 55 min). The highest yield of gynogenotes (16%) was observed at 0.25 0 for female 3, 10 % at 0.30 0 for female 2 and 12% at 0.35 0 for female 1. The percentage of viable gynogenotes responded quadratically to the tau index (s/0) when shock treatments were applied. The higher yields of viable diploid sturgeon gynogenotes were achieved when eggs were heat shocked at embryological ages ranging from 0.25 to 0.35 0 (approximately 14 to 19 min post-activation at 18 °C). No viable hybrids were produced in the control fertilization of sturgeon eggs with intact paddlefish sperm which verified the gynogenetic origin of the offspring produced. © Rapid Science Ltd. 1998     

Improved Cryopreservation of Sperm of Paddlefish (Polyodon spathula)

Experiments were performed to improve protocols for sperm cryopreservation of paddlefish (Polyodon spathula), a species for which there has been limited study. The first experiment was conducted to investigate the effects of two extenders (modified Tsvetkova’s extender: mT and modified Hanks’ balanced salt solution: mHBSS) in combination with methanol (MeOH) and dimethyl sulfoxide in two concentrations (5 and 10%) on the postthaw motility and fertilization rates of cryopreserved sperm. The highest postthaw motility (85 ± 5%) was observed when sperm were frozen using mT extender with 10% MeOH as cryoprotectant. Extenders (P = 0.0018) and cryoprotectants (P = 0.0040) each had a significant effect on the postthaw motility of paddlefish sperm. The highest fertilization (80 ± 3%) was found when eggs were fertilized with sperm frozen with mT extender in combination with 10% MeOH. However, there was no significant difference among fertilization rates when MeOH was used as a cryoprotectant in either concentration or in combination with either mT or mHBSS extenders. In the second experiment, 4000 eggs were fertilized with the pooled contents of five straws of thawed sperm (total volume of 1.25 mL) using mT extender in combination with 5% MeOH, and hatch rates as high as 79 ± 5% were observed. A third experiment was also conducted to clarify the role of MeOH concentration; however, no significant difference was found among fertilization and hatch rates when either 5 or 10% MeOH was used as a cryoprotectant. These results suggest that MeOH is a safe and reliable cryoprotectant for freezing of paddlefish sperm and obtaining viable postthaw sperm for consistent fertilization and hatch rates. Further, this experimental protocol is relatively simple and applicable for commercial hatchery production of paddlefish.     

Age and growth of the Critically Endangered flapper skate,Dipturus intermedius

1. Knowledge of vital data such as growth and age at maturity is necessary to develop effective management strategies for endangered species. The Critically Endangered flapper skate (Dipturus intermedius) is the largest skate in the North Atlantic and growth information, necessary to assess key life-history traits, populations’ growth rates and anticipate their response to management measures, is still lacking.
2. While classical age estimation methods used in fish generally require the analysis of calcified structures, destructive methods are incompatible with conservation objectives for this species. Taking advantage of the high recreational value of the flapper skate, this study uses citizen-science data originating from photo-identification of trophy pictures and tag–recapture data supported by anglers to estimate growth in this Critically Endangered species. Using the growth increments measured between recapture events, an individual-based Von Bertalanffy growth model was fitted to the data using Bayesian inference.
3. The results confirm that the flapper skate is a long-lived species with ages estimated as >40 years for the largest individuals captured. Despite this longevity, the model reveals a relatively fast initial growth but relatively late ages at maturity and significant sex-related differences in both growth rate and maximum size.
4. These results suggest that population growth rate, and therefore recovery, might be much slower than previously reported. By using citizen science this study provides the necessary information to begin understanding population dynamics and monitor the recovery of an iconic Critically Endangered species.