Aspects of fetal physiology from 18 to 37 weeks' gestation as assessed by blood sampling

OBJECTIVE: To construct reference ranges for fetal pH, oxygen pressure (PO2), and hematologic and biochemical blood constituents, which can be used to analyze changes with gestation and differences with maternal values, thus elucidating some aspects of fetal biology and the effects of the maternal and placental environments. METHODS: We assayed venous pH, PO2, hematocrit, glucose, uric acid, urea, creatinine, total protein, total and direct bilirubin, aspartate aminotransferase, alanine aminotransferase, gamma-glutamyltransferase, alkaline phosphatase, lactic dehydrogenase, amylase, pseudocholinesterase, creatine kinase, triglycerides, and cholesterol concentrations in 157 fetuses and 134 mothers who underwent fetal blood sampling from 18 to 37 weeks' gestation. None of the fetuses was infected or had chromosomal, hematologic, or hormonal abnormalities. RESULTS: All the variables analyzed were similar in fetuses sampled at the placental cord insertion (n = 125) or at the intrahepatic vein (n = 32). Maternal and fetal concentrations of glucose (r = 0.79, P < .001), urea (r = 0.96, P < .001), creatinine (r = 0.83, P < .001), and uric acid (r = 0.94, P < .001) correlated significantly, and their differences exhibited significant changes: the maternal-fetal differences of glucose and urea increased, whereas those of uric acid and creatinine decreased with advancing gestation. Fetal pH and PO2 decreased with gestational age, whereas hematocrit increased, similar to what has been described previously. All of the other variables, with the exception of amylase and cholesterol, changed significantly during the investigated period of pregnancy. Gestational age explained at least 40% of the variance in values of fetal total protein, pseudocholinesterase, alanine aminotransferase, creatine kinase, and triglycerides, but only 3-25% of the variation in the remainder. Most enzymes were higher in the fetus than in the maternal circulation, and all except alkaline phosphatase increased with gestational age. The maternal-fetal glucose difference correlated significantly with hematocrit, pH, and PO2, independent of gestational age and independent of each other. CONCLUSION: With the exception of aspartate aminotransferase, all of the analyzed fetal variables were different from the maternal values, and most changed with gestational age. The mechanisms leading to these fetal specificities remain mostly uncertain, but the provision of reference ranges for several blood constituents may be useful in the differential diagnosis of fetal disease.     

Investigation of Ni/4H-SiC diodes as radiation detectors with low doped n-type 4H-SiC epilayers

The development of SiC minimum ionising particle (MIP) detectors imposes severe constrains in the electronic quality and the thickness of the material due to the relatively high value of the energy required to produce an electron–hole pair in this material by MIP against the value for Si. In this work, particle detectors were made using semiconductor epitaxial undoped n-type 4H-SiC as the detection medium. The thickness of the epilayer is on the order of 40 μm and the detectors are realised by the formation of a nickel silicide on the silicon surface of the epitaxial layer (Schottky contact) and of the ohmic contact on the back side of 4H-SiC substrate. The low doping concentration (6×10¹³ cm⁻³) of the epilayer allows the detector to be totally depleted at relatively low reverse voltages (100 V). We present experimental data on the charge collection properties by using 5.486 MeV -particles impinging on the Schottky contact. A 100% charge collection efficiency (CCE) is demonstrated for reverse voltages higher than the one needed to have a depletion region equal to the -particle extrapolated range in SiC. The diffusion contribution of the minority change carriers to CCE is pointed out. By comparing measured CCE values to the outcomes of drift–diffusion simulation, values are inferred for the hole lifetime within the neutral region of the charge carrier generation layer.     

Cobalt-Molybdenum Sulfide Catalysts Prepared by In Situ Activation of Bimetallic (Co-Mo) Alkylthiomolybdates

Unsupported cobalt-molybdenum sulfide catalysts were prepared from bimetallic CoMo alkyl precursors by in situ activation during the hydrodesulfurization (HDS) of dibenzothiophene (DBT). The bimetallic CoMo precursors were prepared by reaction of tetraalkylammonium thiomolybdate salts, (R₄N)₂MoS₄ (where R = H, methyl, butyl, pentyl or hexyl), with CoCl₂ in water at a Co/Mo molar ratio of 0.3. These catalysts exhibit a Swiss-cheese-like morphology, high surface areas (from 52 up to 320 m²/g), high content of carbon (C/Mo = 2.2-3.3) and type IV adsorption-desorption isotherms of nitrogen. The in situ activation of these tetraalkylammonium thiobimetalate precursors leads to a mesoporous structure with pore size ranging from 2 to 4.5 nm. X-ray diffraction showed that the structure of unsupported cobalt-molybdenum sulfide catalysts corresponds to a poorly crystalline structure characteristic of 2H-MoS₂ with low-stacked layers. The nature of the alkyl group strongly affects both the surface area and the HDS activity. The catalytic activity is strongly enhanced when using carbon-containing precursors; the CoMo catalysts prepared by in situ activation of Co/[N(C₄H₉)₄]₂MoS₄ presents the highest HDS activity. The highest surface area of the catalysts was observed for the CoMo catalyst formed from Co/[N(C₆H₁₃)₄N]₂MoS₄.     

Design issue of a new iCub head sub-system

I am presenting a new design for the head sub-system of the humanoid robot iCub. ICub is a humanoid robot platform that has been conceived as a result of the development of the European Project RobotCub. Mechanical problems of the current head sub-system of iCub robot have been studied in order to figure out improvements for a new design. The feasibility of the new design has been checked through dynamic simulations of the head operations. The successful results have shown plots with curve evolutions of smooth shapes and suitable values of important kinematic and dynamic parameters of the head structure.     

Human Resource Management: Guidelines for Effective Introduction of Microcomputer Technology

Microcomputer technology has matured to a point at which its successful assimilation depends more on the proper management of personnel and less on the features of the technology. This article presents a case study that demonstrates how lead users can be identified and recruited to provide a support infrastructure to peers throughout the initiation stage within the organization. The article recommends that managers of microcomputer technology develop an understanding of different user types and apply adaptive human resource management practices     

Correlating indoor and outdoor temperature and humidity in a sample of buildings in tropical climates

The incidence of several respiratory viral infections has been shown to be related to climate. Because humans spend most of their time indoors, measures of indoor climate, rather than outdoor climate, may be better predictors of disease incidence and transmission. Therefore, understanding the relationship between indoor and outdoor climate will help illuminate their influence on the seasonality of diseases caused by respiratory viruses. Indoor-outdoor relationships between temperature and humidity have been documented in temperate regions, but little information is available for tropical regions, where seasonal patterns of respiratory viral diseases differ. We have examined indoor-outdoor correlations of temperature, relative humidity (RH), and absolute humidity (AH) over a 1-year period in each of seven tropical cities. Across all cities, the average monthly indoor temperature was 25 ± 3°C (mean ± standard deviation) with a range of 20–30°C. The average monthly indoor RH was 66 ± 9% with a range of 50–78%, and the average monthly indoor AH was 15 ± 3 g/m³ with a range of 10–23 g/m³. Indoor AH and RH were linearly correlated with outdoor AH when the air conditioning (AC) was off, suggesting that outdoor AH may be a good proxy of indoor humidity in the absence of AC. All indoor measurements were more strongly correlated with outdoor measurements as distance from the equator increased. Such correlations were weaker during the wet season, especially when AC was in operation. These correlations will provide insight for assessing the seasonality of respiratory viral infections using outdoor climate data, which is more widely available than indoor data, even though transmission of these diseases mainly occurs indoors.     

Cd1−xZnxS solid solutions supported on ordered mesoporous silica (SBA-15): Structural features and photocatalytic activity under visible light

A series of Cd_1−xZn_xS (x = 0.05–0.3) photocatalysts supported on ordered mesoporous silica (SBA-15) were prepared and investigated for hydrogen production from water splitting under visible light. Textural, structural and surface photocatalyst properties are determined by N₂ adsorption isotherms, UV–vis, Raman and XPS and related to the activity results in hydrogen production. Raman and XRD results indicated a mutual interaction between Cd and Zn, forming nanoparticles of Cd_1−xZn_xS solid solutions. All Cd_1−xZn_xS/SBA-15 samples showed relatively high activities for hydrogen evolution. The hydrogen production rate is found to increase gradually when the zinc concentration on photocatalysts increases from 0.05 to 0.2, achieving a maximum for the photocatalyst with zinc concentration equal to 0.2. Variation in photoactivity is discussed in terms of modification in the conduction band and light absorption ability of Cd_1−xZn_xS particles derived from the changes in the Zn concentration in the Cd_1−xZn_xS solid solution.     

Sodium phthalamates as corrosion inhibitors for carbon steel in aqueous hydrochloric acid solution

Three compounds of N-alkyl-sodium phthalamates were synthesized and tested as corrosion inhibitors for carbon steel in 0.5 M aqueous hydrochloric acid. Tests showed that inhibitor efficiencies were related to aliphatic chain length and dependent on concentration. N-1-n-tetradecyl-sodium phthalamate displayed moderate efficiency against uniform corrosion, 42–86% at 25 °C and 25–60% at 40 °C. Tests indicated that compounds behave as mixed type inhibitors where molecular adsorption on steel followed Langmuir isotherm, whereas thermodynamic suggested that a physisorption process occurred. XPS analysis confirmed film formation on surface, where Fe⁺² complexes and Fe⁺² chelates with phthalamates prevented steel from further corrosion.