Climate Change and Energy Technologies

The long time scale of the climate change problem and the inherent nature of the carbon cycle bring important implications for present technology development efforts. Even if major technology improvements are achieved for non-carbon-emitting technologies such as energy-intensity improvements, wind, solar, biomass, and nuclear over the course of the 21^st century, most examinations of potential future greenhouse emissions conclude that additional technology development will be required to stabilize greenhouse gas concentrations. The evelopment of an expanded suite of technologies including carbon capture and disposal, hydrogen systems and biotechnology hold the potential to dramatically reduce the cost of stabilizing greenhouse gas concentrations. This paper examines these technologies in the context of a global integrated assessment model of energy, agriculture, land-use, economics, and carbon cycle processes.     

Genetic amniocentesis in biamniotic twin pregnancies by a single transabdominal insertion of the needle

We present a technique to aspirate amniotic fluid from both sacs in biamniotic twin pregnancies using a single abdominal insertion with a spinal needle. It was successful in 48 out of 55 cases of biamniotic twin pregnancies referred to our perinatal unit between 1985 and 1994. The single insertion technique was used when the inter-amniotic membrane was clearly evident and two separate free amniotic fluid pools could be reached by the operator with a single puncture. An adequate amount of amniotic fluid was sampled from both sacs to make a cytogenetic diagnosis in all cases. There were four fetuses with trisomy 21 in three twin pregnancies. In two cases, only one twin was affected whilst the co-twin was normal, so that a selective feticide was performed. No miscarriages due to genetic amniocentesis were reported. After 1990, all genetic amniocenteses in biamniotic twin pregnancies (except for one case due to late booking) were performed between 14 and 15 weeks of gestation and with all cases except one, it was possible to sample both twins by a single puncture. We suggest that early amniocentesis (14–15 weeks) by a single abdominal puncture could be a reliable and safe alternative to first-trimester chorionic villus sampling in twin pregnancies.     

An accessory marker derived from chromosome 20 and its co-existence with a mosaic trisomy 20 cell line

We report a 16-month-old boy with delayed psychomotor development, dysmorphic features, and failure to thrive. He had a mosaic karyotype detected prenatally: mos 46,XY/47,XY,+r(20)/47,XY,+20. After birth, the abnormal cell lines were confirmed in a number of tissues. The small ring chromosome was identified using fluorescence in situ hybridization as derived from chromosome 20. We compared our patient with previously reported cases of mosaic trisomy 20 detected prenatally and associated with an abnormal phenotype. In an attempt to characterize an r(20) syndrome, we also compared our case with two similar reports in the literature.     

Thyroid antibodies are not a risk factor for pregnancies with down syndrome

The observation that thyroid disease is frequent in mothers of children with Down syndrome (DS) has suggested that maternal thyroid antibodies could be a factor predisposing to trisomy 21 in their offspring. In this study, the incidences of thyroglobulin (Tg) and thyroid peroxidase (TPO) antibodies were analysed with a sensitive solid-phase immunosorbent radioassay in sera from 29 mothers giving birth to children with trisomy 21 and 87 control mothers. The serum samples were collected at delivery. There was no statistical difference regarding the proportion of thyroid antibodies (against Tg and/or TPO) in the two groups. Thyroid antibodies were detected in 6/29 (20.7 per cent) of the DS mothers and in 23/87 (26.4 per cent) of the control mothers. Among the women with thyroid antibodies, 4/6 (66.7 per cent) of the DS mothers and 12/23 (52 per cent) of the control mothers had antibodies against both Tg and TPO. There was no increase in the relative risk of having a child with DS if the titre of either Tg or TPO antibodies or both were positive, i.e. ≥ 1/5. The results indicate that the presence of thyroid antibodies in the serum of a pregnant woman has no prognostic value for the birth of an infant with DS.     

Fluid Mechanics of Biological Surfaces and their Technological Application

 A survey is given on fluid-dynamic effects caused by the structure and properties of biological surfaces. It is demonstrated that the results of investigations aiming at technological applications can also provide insights into biophysical phenomena. Techniques are described both for reducing wall shear stresses and for controlling boundary-layer separation. (a) Wall shear stress reduction was investigated experimentally for various riblet surfaces including a shark skin replica. The latter consists of 800 plastic model scales with compliant anchoring. Hairy surfaces are also considered, and surfaces in which the no-slip condition is modified. Self-cleaning surfaces such as that of lotus leaves represent an interesting option to avoid fluid-dynamic deterioration by the agglomeration of dirt. An example of technological implementation is discussed for riblets in long-range commercial aircraft. (b) Separation control is also an important issue in biology. After a few brief comments on vortex generators, the mechanism of separation control by bird feathers is described in detail. Self-activated movable flaps (=artificial bird feathers) represent a high-lift system enhancing the maximum lift of airfoils by about 20%. This is achieved without perceivable deleterious effects under cruise conditions. Finally, flight experiments on an aircraft with laminar wing and movable flaps are presented.     

Analysis of the hydrocyclone stock cleaning process for wasted fibre in a paper mill

The main objective of this project was to evaluate the possibility of reducing the quantity of fibre wasted at one of many hydrocyclone (centrifugal) cleaning processes in a paper mill. It was found that the application of elutriation water to both the tertiary and quaternary cleaners was essential to minimise the fibre discharged to the sewer, and the pressure of this elutriation water had a dramatic effect of reducing the fibre wastage. Accordingly, it has been shown that 150–160 kPa as the optimum pressure range to apply elutriation water to minimise the product grade fibre wasted whilst sending undesired shive fibre to the sewer. Also, monitoring of the press uhle box wastewater revealed that the paper mill has the potential to make substantial cost savings by reducing the waste stream. Further investigation is necessary to determine the types of fibre that are being wasted, and the viability of a screen to recycle the wasted fibre to the process. However, these fibres may be unsuitable to reuse in the process and alternative uses must be found.     

Genetic amniocentesis following multifetal pregnancy reduction to twins: Assessing the risk

Fifty-three patients who elected to reduce their pregnancies to a twin gestation in our centre are known to have subsequently undergone genetic amniocentesis. Five of these patients lost their entire pregnancy following the genetic amniocentesis procedure. This is equivalent to a 9·4 per cent pregnancy loss rate for reduced twin gestations in comparison with an expected loss rate of 2 per cent for non-reduced twin gestations.     

Uncommon chromosomal mosaicism in chorionic villi

Three cases of unusual chromosomal mosaicism are reported for which the cytogenetic data show inconsistent findings between CVS and AC or fetal tissue, and which cannot be explained simply by non-disjunction. For case 1, in CVS the karyotype was 46,XY, whereas lymphocytes and fibroblasts revealed 69,XXY. DNA fingerprinting indicated one paternal and two maternal chromosome sets, the latter most probably due to omission of maternal meiosis II. For case 2, in CVS mos 46,XX/47,XX,+mar de novo was observed. Amniotic fluid cells had the karyotype 46,XX. The origin of the marker chromosome might be explained by at least two events of unknown order (a somatic chromosome/chromatid deletion and non-disjunction of the homologous chromosome). In case 3 (CVS: mos 46,XY/46,XY,19q+ de novo; amniotic fluid cells, lymphocytes, and fibroblasts: 46,XY), the surplus of chromosome material in 19q+ might be explained on the basis of a somatic translocation. The idea of a chimera is less convincing, as the mosaic finding is restricted to one tissue. Furthermore, there was no hint of a vanishing twin. Hitherto, no case of structural chromosome mosaicism in CVS has been reconfirmed in fetal tissues.