Biomedical subjects

Yingxin Liu

Publications and source records attributed to Yingxin Liu.

3 recordsLinked to original sources

PubMed2006

Switchable surfactants.

Many industrial applications that rely on emulsions would benefit from an efficient, rapid method of breaking these emulsions at a specific desired stage. We report that long-chain alkyl amidine compounds can be reversibly transformed into charged surfactants by exposure to an atmosphere of carbon dioxide, thereby stabilizing water/alkane emulsions or, for the purpose of microsuspension polymerization, styrene-in-water emulsions. Bubbling nitrogen, argon, or air through the amidinium bicarbonate solutions at 65 degrees C reverses the reaction, releasing carbon dioxide and breaking the emulsion. We also find that the neutral amidines function as switchable demulsifiers of an aqueous crude oil emulsion, enhancing their practical potential.

Journal Article↗

PubMed2005

Optimal fetal growth for the Caucasian singleton and assessment of appropriateness of fetal growth: an analysis of a total population perinatal database.

BACKGROUND: The appropriateness of an individual's intra uterine growth is now considered an important determinant of both short and long term outcomes, yet currently used measures have several shortcomings. This study demonstrates a method of assessing appropriateness of intrauterine growth based on the estimation of each individual's optimal newborn dimensions from routinely available perinatal data. Appropriateness of growth can then be inferred from the ratio of the value of the observed dimension to that of the optimal dimension. METHODS: Fractional polynomial regression models including terms for non-pathological determinants of fetal size (gestational duration, fetal gender and maternal height, age and parity) were used to predict birth weight, birth length and head circumference from a population without any major risk factors for sub-optimal intra-uterine growth. This population was selected from a total population of all singleton, Caucasian births in Western Australia 1998-2002. Births were excluded if the pregnancy was exposed to factors known to influence fetal growth pathologically. The values predicted by these models were treated as the optimal values, given infant gender, gestational age, maternal height, parity, and age. RESULTS: The selected sample (N = 62,746) comprised 60.5% of the total Caucasian singleton birth cohort. Equations are presented that predict optimal birth weight, birth length and head circumference given gestational duration, fetal gender, maternal height, age and parity. The best fitting models explained 40.5% of variance for birth weight, 32.2% for birth length, and 25.2% for head circumference at birth. CONCLUSION: Proportion of optimal birth weight (length or head circumference) provides a method of assessing appropriateness of intrauterine growth that is less dependent on the health of the reference population or the quality of their morphometric data than is percentile position on a birth weight distribution.

Anthropometry↗

PubMed2004

Choosing the best estimate of gestational age from routinely collected population-based perinatal data.

Obtaining gestational data of acceptable validity on whole populations is a considerable challenge, which must be met in order to further epidemiological investigation involving perinatal factors. As the means of estimating gestational duration multiply, routinely available population data pertaining to gestational duration may be conflicting. This exacerbates its reputation for unreliability, which is due primarily to the generally occult nature of conception and secondly to the propensity for data entry errors of the data from which gestational duration is estimated. However, the key to improving reliability may paradoxically lie in the increasing variety of methods for estimating gestational duration, because agreement between independent observations increases the reliability that can be placed on estimates of factors that are inherently difficult to measure. This paper demonstrates that the acceptability of population data for gestational duration can be improved by simple rectification of recurring data entry errors and demanding compatibility of two independent estimates of gestational duration. Compared with the previous algorithm that relied primarily on last menstrual period data, the new algorithm, that considers both antenatal and neonatal indicators of gestational duration, decreased the proportion of births in a geographically defined birth cohort 1986-99 (n=354,216) without a gestational estimate, from 0.5% to 0.03%, halved the number of births of >400 g estimated to occur before 20 weeks, and almost eliminated gestational estimates of >45 weeks.

Algorithms↗