Semilobar holoprosencephaly in a 46,XY female fetus

We report the prenatal echographic diagnosis of holoprosencephaly (HPE) at 11 weeks' gestation. Fetopathological examination revealed an unusual variant of semilobar HPE with middle interhemispheric fusion associated with sex-reversal: 46,XY normal male karyotype, normal external and internal female genitalia and streak gonads. Copyright © 2001 John Wiley & Sons, Ltd.     

Effects of aeration on water quality from septic system leachfields

We conducted a pilot-scale study at a research facility in southeastern Connecticut to assess the effects of leachfield aeration on removal of nutrients and pathogens from septic system effluent. Treatments consisted of lysimeters periodically aerated to maintain a headspace O(2) concentration of 0.209 mol mol(-1) (AIR) or vented to an adjacent leachfield trench (LEACH) and were replicated three times. All lysimeters were dosed with effluent from a septic tank for 24 mo at a rate of 12 cm d(-1) and subsequently for 2 mo at 4 cm d(-1). LEACH lysimeters had developed a clogging mat, or biomat, 20 mo before the beginning of our study. The level of aeration in the AIR treatment was held constant regardless of loading rate. No conventional biomat developed in the AIR treatment, whereas a biomat was present in the LEACH lysimeters. The headspace of LEACH lysimeters was considerably depleted in O(2) and enriched in CH(4), CO(2), and H(2)S relative to AIR lysimeters. Drainage water from AIR lysimeters was saturated with O(2) and had significantly lower pH, five-day biological oxygen demand (BOD(5)), and ammonium, and higher levels of nitrate and sulfate than LEACH lysimeters regardless of dosing rate. By contrast, significantly lower levels of total N and fecal coliform bacteria were observed in AIR than in LEACH lysimeters only at the higher dosing rate. No significant differences in total P removal were observed. Our results suggest that aeration may improve the removal of nitrogen, BOD(5), and fecal coliforms in leachfield soil, even in the absence of a biomat.     

Assessment of application-rate dependent effects of a long-term fire retardant chemical (Fire Trol 934) on Typha domingensis germination

Although long-term fire retardants (LTR) gain increasingly acceptance as effective tools for wildfire management, recent studies indicate their potential harmfulness in the environment, especially in aquatic ecosystems. This study comprises a first laboratory impact assessment of LTR action in temporal Mediterranean wetlands, using seed germination of Typha domingensis as indicator of impact. Our aim was to identify application rates upon which seed germination could be significantly affected. We tested for low (1 l m(-2)) and high (3 l m(-2)) application rates of Fire Trol 934 which are recommended by the manufacturers as a function of fuel characteristics. In addition, we simulated the impact of a higher application rate of 5 l m(-2) because inhomogeneous dispersal of the LTR during fire control and prevention operations can result in locally elevated applications. Results of a microcosm experiment indicate that application rates of 1 or 3 l m(-2) can impact Typha germination rates in the short-term via indirect LTR-mediated effects on water quality, which suppressed necessary cues for germination. However, a subsequent experiment with Petri dishes, using seeds isolated from the LTR treated sediments did not show significantly different germination rates between the control and the treatments with application rates of 1 or 3 l m(-2). This suggests that retardant pre-application germination success could be recovered in nature once the retardant is eliminated. By contrast, seeds almost completely failed to germinate in the microcosm experiment and the subsequent Petri dish essay when an application rate of 5 l m(-2) was used. This suggests a critical level upon which Typha seed germination may be perpetually limited. Research should be extended to other plant species to provide fire managers with guidelines for environmentally safe use of LTR in the Mediterranean region.     

Degradation of 14C-atrazine bound residues in brown soil and rendzina fractions

The remobilization and the fate of 14C-ring labeled atrazine (6-chloro-N2-ethyl-N4-isopropyl-1,3,5-triazine-2,4-diamine) bound residues was examined in relation with the turnover of natural soil organic matter. Soil fractions of a brown soil and a rendzina were incubated under controled laboratory conditions. The mineralization of natural organic matter and atrazine-bound residues was respectively estimated by the amounts of CO2 and 14CO2 evolved during the incubation. The remobilization and distribution of 14C residues among the soil organic fractions were achieved after physical-chemical extractions of the samples. Comparisons of samples in abiotic and biotic conditions allowed us to assess the influence of microbial activity on the fate of atrazine-bound residues. The mineralization curves showed that natural organic matter and atrazine-bound residues had similar decomposition patterns. After 100 d of incubation, 0.8 to 3.6% of total organic C was evolved as CO2, while only 0.1% of the initial radioactivity was mineralized as CO2, and 7 to 15% was becoming extractable with water and methanol. Few differences were observed in the distribution of residues within organic compounds for both fractions of the rendzina, except a decrease of the 14C radioactivity of the 50- to 5000-microm fraction and a slight increase of that of humin. For the 0- to 5000-microm brown soil fraction, increased radioactivity in humin at the expense of humic (HA) and fulvic (FA) acids was detected after incubation, while for the 0- to 50-microm fraction more radioactivity was recovered with FA.     

安钢90 m2烧结机尾除尘工艺设计特点

介绍了安钢90 m2烧结机尾除尘工艺设计中的设备选型、系统配置、管网阻力平衡的特点及应注意的几个问题.     

SJ10000风机出口气流强烈脉动现象初探

通过对 SJ10 0 0 0风机运行工况进行监测 ,对管网系统进行校验 ,以此为依据对风机出口强烈脉动现象进行了分析。采取降低管道阻力或提高风机静压力等措施来消除风机出口气流强烈脉动。     

喜马拉雅山中段北坡对流层中上部大气降水化学的高程分布特征

1997年夏季在希夏邦马峰北坡达索普冰川区(28°33′N,85°44′E)海拔5800m～7000m区间对4次降雪过程进行了系统的采样工作,目的是认识全球偏远地区对流层中上部大气成分的高程分布特征.达索普冰川区夏季4次降水中,局地大陆性气团降水SO₄^2-、NO₃^-、Ca²⁺和Mg²⁺之间存在显著的正相关性,而海洋性气团降水4种离子之间的相关性变化较大,说明在夏季低尘埃阶段大气中各种离子的主导来源处在短期的(如数天)变化中.这种离子主导来源的变化同时也影响了降水中离子的高程分布特征.总体上达索普冰川区夏季降水中NO₃^-、Ca²⁺、Mg²⁺浓度随海拔的升高呈减小趋势,SO₄^2-浓度则为增大趋势.