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The secondary electron emission (SEE) of ZnO-coated carbon nanotubes (CNTs) was measured using a biasing technique in a scanning electron microscope. The SEE yield of the ZnO-coated CNTs is higher than that of the ZnO film deposited on Si substrates. Direct observation of the variation in SEE from tip-end and non-CNT positions was demonstrated. Local measurement reveals that the SEE yield at the tip-end of the ZnO-coated CNTs is much higher than that of non-CNT positions. The enhancement of SEE is attributed to the strong local field generated at the tip of the CNTs.

We report the formation of a stable superhydrophobic surface via aligned carbon nanotubes (CNTs) coated with a zinc oxide (ZnO) thin film. The CNT template was synthesized by chemical vapor deposition on an Fe-N catalyst layer. The ZnO film, with a low surface energy, was deposited on the CNT template by the filtered cathodic vacuum arc technique. Contact angle measurement reveals that the surface of the ZnO-coated CNTs is superhydrophobic with water contact angle of 159 degrees . Unlike the uncoated CNTs surface, the ZnO-coated CNTs surface shows no sign of water seepage even after a prolonged period of time. The wettability of the surface can be reversibly changed from superhydrophobicity to hydrophilicity by alternation of ultraviolet (UV) irradiation and dark storage.

We present the CT and MRI findings of an 8-day-old infant with an infected cephalhaematoma complicated by skull osteomyelitis, venous sinus thrombosis and left cerebellar haemorrhage.

Discriminant analysis was used to differentiate between extrahepatic biliary atresia and intrahepatic cholestasis. Among the ten laboratory variables tested, three (gamma-glutamyl transpeptidase, alkaline phosphatase and total serum bilirubin) were useful in the differential diagnosis. gamma-Glutamyl transpeptidase contributed most to the discrimination (85%). From a population study of 28 babies with extrahepatic biliary atresia and 24 infants with intrahepatic cholestasis, the procedure achieved a diagnostic accuracy and specificity of 92.9% and an efficiency of 92.3%. The jackknife procedure has also confirmed that the mathematical model was robust for discriminant analysis and therefore it may be valid for screening infants with cholestasis for early surgical intervention. Discriminant analysis is a useful adjunct for differentiation between intrahepatic cholestasis and extrahepatic biliary atresia.

The properties of body mass indices were evaluated in a cross sectional study of the weights and heights of 5016 Chinese boys and girls aged between 3 and 18 years. Of the indices examined (weight/height (W/H), weight/height2 (W/H2), weight/height3 (W/H3) and weight/heightp (W/Hp], W/Hp was the only one that consistently showed least correlation with height, and so could be regarded as the optimal body mass index by the criterion of independence of the index from height. The exponent 'p' of W/Hp is, however, highly dependent on age; the value increases steadily between the age of 3 and 7-9 years, and then varies considerably around puberty. Only the age specific exponent ensures a lack of correlation between body mass index (W/Hp) and height. Age specific W/Hp should therefore be used in intrapopulation studies of weight or problems associated with obesity in children. Interpopulation comparison of weight and adiposity by W/H, W/H2, or W/H3 may give misleading results because of their dependence on height. Our results also suggest that the conventional weight for height charts may not be accurate enough for clinical use.

Spirometric data from 1586 healthy children, who did not smoke, were analysed to examine the effects of overweight as measured by the body mass index (weight/height2) on lung function. Overweight (72 boys, 88 girls) was defined as on or above the 90th percentile weight for height. After having controlled for the confounding variables of height and age, there were positive partial correlations between body mass index and lung function in girls whose weight was normal, in overweight girls, and in boys whose weight was normal, but not in overweight boys. In contrast to adults, body mass index has a positive effect on lung function in girls, whatever their weight. No such correlation between body mass index and lung function was seen in overweight boys. The observations may be accounted for by distinct sex dependent patterns of fat distribution in children.

Glucose-6-phosphate dehydrogenase (G-6-PD) deficiency is a common X-linked recessive disorder among the Chinese population. Neonatal screening for this condition is important and with necessary precaution, enzyme deficient infants are less likely to develop severe haemolysis and subsequent kernicterus. Screening of G-6-PD deficiency by fluorescent spot test on cord blood samples of 1228 Chinese neonates revealed an incidence of 4.4% in males and 0.35% in females. Simultaneous direct enzyme assay confirmed the sensitivity and specificity of the spot test in the identification of male hemizygotes and female homozygotes. However, the spot test was unsatisfactory in detecting heterozygotes. Even quantitative enzyme assay could detect only 70% of the partially deficient subjects.

The application of the transcutaneous bilirubinometer in screening for neonatal jaundice was evaluated in 259 full-term Chinese infants: 202 who had not received any treatment and 57 who were receiving phototherapy. The transcutaneous bilirubin index correlated well with the serum bilirubin level (SB) of the untreated infants and the coefficient of correlation was slightly higher for TcB readings obtained over the mid-sternal area (r = 0.91; P less than 0.001) than those over the forehead (r = 0.85; P less than 0.001). Transcutaneous bilirubinometry was unreliable in predicting the SB level in infants receiving phototherapy even if the SB readings were obtained over shaded skin. The haematocrit of the infants, though having a statistically significant effect on the TcB index, contributed only minimally to the regression line and correlation coefficient between the TcB index and SB level.

The measurement of hydrogen (H2) in breath is becoming increasingly useful as a diagnostic and research tool, but there is still no satisfactory method of sampling expired air in infants and small children. We tested a modified open-flow hood method where the child's head is put in a perspex box and expired air is collected by sucking air from the box by means of an air pump. Comparison of this method with end-expiratory sampling by a modified Haldane-Priestly and nasopharyngeal catheter gave a correlation coefficient of 0.83 and 0.65, respectively. We conclude that expired air sampling in children with this method is a more satisfactory and as reliable a method as any available at present, and has the added advantage of being quantitative.

Two patients with toxaemia of pregnancy presented with cortical blindness. Immediate cranial computed tomography (CT) demonstrated bilateral hypodense areas in the occipital lobes. Both patients underwent Caesarean section for delivery. There was gradual and complete recovery of vision, together with CT documentation of resolution of the cerebral changes, indicative of the reversible nature of the ischaemic lesion.

Despite limited health resources, the Chinese have achieved reasonably good perinatal and neonatal mortality rates comparable to those of many developed countries. China, Hong Kong and Singapore, areas with different socioeconomic structures, have shared the same favourable ethnic determinants of perinatal mortality. The Chinese have much lower incidence of very low birthweight babies (less than 1000 g) and lethal congenital anomalies. The former is probably related to the rarity of teenage pregnancy, maternal smoking and alcohol consumption. Asphyxia remains a major contributor to perinatal deaths. The perinatal mortality rate in mainland China has remained relatively unchanged in contrast to the dramatic falling trend in Hong Kong and Singapore in the past two decades. This may be accounted for by differences in socioeconomic conditions despite their identical ethnic origin. Studying the Chinese sociocultural pattern may have a great impact on perinatal mortality by preventing low birthweight babies.

A prospective study of 1238 full-term Chinese newborn infants was conducted to determine the incidence of neonatal jaundice and associated factors. A significantly more severe degree of hyperbilirubinaemia was present in infants whose ABO blood group was incompatible with that of their mothers and those who were deficient in the enzyme glucose-6-phosphate dehydrogenase (G6PD). Among the remainder, clinical jaundice was present in 87% and 23.9% had a peak serum bilirubin (SB) concentration greater than 204 mumol/l. Factors that were found to have an association with a higher peak SB concentration included: male infants; elder siblings who had a history of neonatal jaundice; and breast-fed infants with or without supplementation with formula feed. Factors that were found to have no significant association with the peak SB concentration were: gestational age; birthweight; the mode of delivery of the infants; maternal consumption of Chinese herbs and syntocinon induction or augmentation of labour.

An epidemiological study of perinatal colonization of group B streptococcus (GBS) was carried out prospectively in a Chinese population. One hundred and sixty-eight mother-infant pairs were studied. Maternal carriage rate from multiple sites was 19.0%, with an overall neonatal colonization rate of 19.6%. There was no neonatal sepsis due to GBS. No obstetrical risk factors that could influence material carriage could be identified. Neonatal colonization was associated with premature/prolonged rupture of membranes, increased duration of rupture of membranes and intrapartum pyrexia. The number of infected sites and the density of organism in each site in the infant were directly proportional to the number and density of organisms in the culture-positive sites in the mother. Serotypical study showed a complete absence of type II GBS in this population. Since the vertical transmission rate was only 37.5%, it is postulated that nosocomial spread of the organism contributed significantly towards colonization of the infants in our study population.

The liver functions of 17 babies with extrahepatic biliary atresia (EHBA) and 19 babies with neonatal hepatitis (NNH) were analyzed. The serum gamma-glutamyl transpeptidase (GGTP) level and its rate of rise were significantly higher in the EHBA group. Both cross-sectional and longitudinal studies showed a positive correlation between the GGTP activity and the duration of the disease. The diagnostic accuracy is 79% for EHBA and 95% for NNH. It is suggested that GGTP and its rate of rise are the most important biochemical parameters in the differential diagnosis of these two diseases.

Thirty four term babies with physiological jaundice were subjected to continuous phototherapy and to two regimens of intermittent phototherapy. The difference in serum bilirubin kinetics between the three groups of treated babies was insignificant; a schedule of one in four hours of irradiation achieved the same treatment effect as continuous phototherapy.