水泵水轮机甩负荷过程流动诱导噪声数值模拟

为研究水泵水轮机甩负荷过程压力脉动特性及其流动诱导噪声,该文基于网格壁面滑行技术和DES湍流模型,对水泵水轮机发电工况下导叶关闭过程进行连续性模拟,并将流场叶片表面压力脉动信号作为声场流动诱导噪声计算声源,通过对压力脉动特性和流动诱导噪声分析得到：导叶进出口处2个无叶区内压力脉动主频位置均在叶频为斯特劳哈尔数等于0.051与1处,导叶出口处频谱值是进口处10倍之上,说明动动干涉对流态的影响强于动静干涉;当尾水管内出现2个反向旋壁涡带时,压力脉动最强烈且其幅值最大。声场分析结果表明外场噪声的主频由压力脉动主频与壳体固有频率综合决定,声压分布具有"∞"形式的指向形态,且各阶叶频处声压分布呈现出明显的对称性,说明叶片噪声辐射具有明显的偶极子特性;在一阶、二阶叶频处,导叶关闭前一半阶段,流量对于外场噪声辐射能力的影响表现为大流量工况下最强,小流量工况下最弱,导叶关闭后一半阶段正好相反。     

Effects of the lack of forest management on spatiotemporal dynamics of a subalpine Pinus cembra forest

Knowledge about the stand structure and dynamics of subalpine forests is crucial to preserve their multifunctionality. In the present study, we reconstructed the spatiotemporal dynamics of a subalpine Pinus cembra forest in the eastern Italian Alps in response to natural disturbances and forest management. We adopted a concurrent point pattern, dendroecological and growth dominance (GD) analysis. We mapped and measured all trees of Pinus cembra and Larix decidua in a 1?ha plot. We analyzed intra- and interspecific spatial patterns and spatial autocorrelation of tree size and age. We explored establishment dynamics and shifts in competition by analyzing growth suppression/release patterns and GD trends. Results showed a clumped, uneven-aged, multilayered structure where pine was dominant. The synergic action of ecological and human-induced factors is discussed to explain the prevalence of pine over time. Spatial pattern and autocorrelation analyses suggest a different colonization strategy of the two species, in which pine established after small-scale perturbations and experienced a stronger inter- and intra-specific competition. The interruption of tree establishment and shift in GD toward large trees resulting from the lack of forest management are the most important findings of this research. This highlights the importance of an active management to avoid the homogenization of the forest structure that is generally associated with a reduction in biodiversity and protective ability of forests.     

Prevalence of overweight and obesity among school-aged children in urban, rural and mountain areas of the Veneto Region, Italy

OBJECTIVE: To define the prevalence of overweight and obesity among school-aged children resident in mountain areas, rural areas and urban areas.Design, setting and subjectsThe sample (n = 12 832; 50.7% boys) included 9- and 11-year-old children of the Veneto Region of north-east Italy. Overweight and obesity status were determined using the International Obesity Task Force cut-off points for body mass index. The prevalence of overweight and obese subjects was calculated with a confidence interval of 95%. The Mantel-Haenszel method was used to compare the combined prevalence of overweight and obesity among children resident in mountain areas, rural areas and urban areas. RESULTS: Among boys the prevalence of overweight was 21.06%, while obesity prevalence was 5.92%; among girls overweight prevalence was 21.30%, while obesity prevalence was 5.15%. The prevalence was higher among 11-year-old boys (odds ratio (OR) = 1.19; 95% confidence interval (CI): 1.06-1.33) and 9-year-old girls (OR = 1.13; 95% CI: 1.01-1.26). Children resident in rural areas presented a higher risk of overweight and obesity compared with children resident in mountain areas (Mantel-Haenszel OR = 1.27; 95% CI: 1.13-1.42; chi2 = 17.55; P < 0.0001) and in urban areas (Mantel-Haenszel OR = 1.18; 95% CI: 1.07-1.31; chi2 = 10.39; P < 0.001). CONCLUSIONS: A relevant prevalence of overweight and obesity was found; the excess weight concerns one child in four. There are differences linked to different geographical areas that must be further investigated.     

ULTRASONOGRAPHIC FEATURES OF GRASS AWN MIGRATION IN THE DOG

The aim of this study was to describe the ultrasonographic features of grass awns in soft tissue. A 10 MHz linear transducer was used. Ultrasound images from 25 dogs (27 awns) were collected and compared with the results from water bath studies using wild oat seeds (Avena spp.) collected in the field. Wild oat seeds were the most common grass awn found in soft tissue of dogs. Ultrasonographically grass awns appeared as a double/triple spindle-shaped echogenic interface within soft tissue. The same appearance was observed in water bath studies. In four dogs, the grass awn was removed surgically with a clamp introduced into a fistulous tract, using sonographic guidance. The grass awn was not found surgically in only three dogs, suggesting more attention during surgery. Ultrasonography is a useful diagnostic imaging technique to identify grass awns within soft tissue.     

水牛活体采卵及体外受精研究

应用B型超声波采卵法进行水牛活体采卵,42头3～17岁良种水牛间隔3 d采卵1次,连续采卵2～3次,共进行96次,穿刺卵泡762个,回收卵母细胞513枚,其中可用卵母细胞305枚,回收率67.3%,可用卵占回收卵总数59.5%,平均每头次获卵母细胞5.34±4.25枚,其中可用卵母细胞3.18±2.89枚.采集的可用卵母细胞以MC和SOF 2种系统培养,受精分裂率和囊胚率分别为45.2%、30.6%和70.8%、18.8%.用8枚胚胎移植受体母牛8头,妊娠2头,产下了世界第1例由沼泽型水牛孕育生产的河流型水牛.     

Pneumonia disease assessment using a slaughterhouse lung-scoring method

The aims of this study were the evaluation of a quantitative method for the assessment of pneumonia lesions applied to heavy-weight slaughtered pigs, the identification of risk factors connected with the increase in the prevalence and severity of the lesions and the evaluation of a possible correlation between the presence of pneumonia lesions and the decrease in the carcass quality. The lungs of 10 041 pigs (109 slaughtered batches) coming from 91 farms located in Northern Italy were examined. Lung lesions were scored using the method developed by Madec and Kobisch (Journ. Rech. Porc. Fr., 14, 1982, 405). Before the scoring, anamnestic information regarding the farm of origin of each batch were collected. For 41 batches (3603 pigs), information about carcass quality were also collected. Pneumonia lesions were found in 59.6% of the lungs (range 3-91%), and the average batch score was 2.11 (range 0.03-7.15). We identified as farm risk factors those related to an increase in the severity of the lung lesions, the presence of breeders within the herd, the starting of a growing cycle during the winter season and the lack of vaccination programmes to Mycoplasma hyopneumoniae. Moreover, we also found a statistically significant association between the increase in the mean lung score of the batch and the decrease of the carcass quality.     

Lactobacillus rhamnosus as additive for maize and sorghum ensiling

The effects of Lactobacillus rhamnosus AT195, a potential probiotic microorganism cultured in buffalo "scotta" whey, on chemical and microbiological composition in maize and sorghum ensiling were evaluated. Both crops were harvested, chopped, and treated or not with the selected strain prior to ensiling in fiberglass vertical silos; 90 days after ensiling, silages were sensorially evaluated and sampled. Different chemical components were evaluated both on fresh crops and silages: in particular, the water-soluble carbohydrates content was investigated by high-field NMR spectroscopy and the carbohydrate fermentation profile was performed by GC. Besides phenotypic identification and typing, microbiological studies included Lb. rhamnosus genotype typing by RAPD-PCR. All silages, inoculated or not, were well preserved, as their chemical and microbiological data along with the fermentation profiles showed. The selected strain used as inoculum influenced the lactic acid population of silages and evidenced a good survival performance during the ensiling process of both maize and sorghum. Moreover, the use of Lb. rhamnosus strain efficiently improved the quality of the multifactorial ensiling process by significantly reducing the ammonia nitrogen content of both maize and sorghum silages.     

Reversible and washing resistant textile-based optical pH sensors by dyeing fabrics with curcuma

Curcuma powder was used to dye cotton and polyamide 6,6 fabrics in order to produce textile-based optical pH sensors. Both fabrics showed a bright yellow color after dyeing and demonstrated color changes (towards red) when contacted with basic solutions. Color change and sensitivity differ for cotton and for polyamide. Curcuma-dyed cotton shows color changes in particular in the range of pH between 6.5 and 8.5, whilst curcuma-dyed polyamide shows a wider pH range: from 8.5 to 13.0. The stability of pH sensing to washing was evaluated. Three different kinds of washing agents were used in order to simulate the real life conditions of a garment or a cloth. Standard test methods were used when available for washing tests. The pH sensing of the curcuma-dyed fabrics demonstrated an excellent fastness to all kinds of washing. Ionic strength of the solution does not affect the color changes. Moreover, color reversibility of the fabrics was proven, too. Color change and reversibility of the fabrics was assessed by an UV-visible spectrophotometer. Spectral changes were observed at 540 nm for curcuma-dyed cotton, and at 487 and 574 nm for polyamide.