CH Values Research Articles

Оценка численности хондроцитов в суставном хряще при дистракционном остеосинтезе голени в комбинации с накостной пластиной

Introduction The number of chondrocytes in the articular cartilage of the femoral condyles and talus junction surface in the conditions of distraction osteosynthesis of the tibia with the Ilizarov apparatus combined with plating was estimated. Material and methods Seven dogs underwent tibial lengthening at a daily rate of 1 mm for 4 steps and to 14–16 % of the initial length of the segment with the use of the Ilizarov apparatus and plating. Stages of the study were days 30 and 90 in the fixation phase when only plating was left. Histomorphometry of semi-thin sections of the articular cartilage was carried out with the help of an Opton photomicroscope (Germany), DiaMorf software complex (Russia) and VideoTest-Master morphology program. The proportion of chondrocytes (N ch, %), the proportion of empty lacunae (NN em.lac, %), and isogenic groups (NN is.gr, %) were determined in the total sample volume of 200 lacunae. A control group was articular cartilage of five intact dogs. Results The articular cartilage of both articular surfaces retained the zonal structure. Disorder in the homogeneity of the superficial part of the surface zone and destruction of a part of chondrocytes were noted. In the articular cartilage of the femoral condyles, the Nch value was lower than in the control animals by 5.74 %. NN em.lac was increased 2.3 times while NN is.gr values decreased to 2.06 % in the femoral condyle articular cartilage after 30 days of fixation period with the plate. After 90 days of fixation, the N ch values were lower with respect to the controls by 3.73 %. Low values of NN is.gr (4.3 %) and high values of NN em.lac (27.54 %) were maintained. In the articular cartilage of the talus, N ch was lower than in the control group by 1.98 %; NN em.lac increased 1.5 times and NN is.gr decreased to 4.7 % relative to controls after 30 days of fixation. After 90 days, the value of NN em.lac remained at the same level as in the previous experiment stage. The values of NN is.gr were comparable with the control group. Conclusion The technique of distraction osteosynthesis of the tibia in combination with plating is of low traumatic effect on the adjacent joints. A comparative analysis of quantitative parameters of the articular cartilage revealed that the most vulnerable site was the articular cartilage of the femoral condyles.

Observation‐based parameterization of air‐sea fluxes in terms of wind speed and atmospheric stability under low‐to‐moderate wind conditions

AbstractThis study explores the behavior of the exchange coefficients for wind stress (CD), sensible heat flux (CH), and water vapor flux (CE) as functions of surface wind speed (U10) and atmospheric stability using direct turbulent flux measurements obtained from a platform equipped with fast‐response turbulence sensors in a low‐to‐moderate wind region. Turbulent fluxes are calculated using the eddy‐correlation method with extensive observations. The total numbers of quality‐controlled 30 min flux runs are 12,240, 5813, and 5637 for estimation of CD, CH, and CE, respectively. When adjusted to neutral stability using the Monin‐Obukhov similarity theory (MOST), we found that CDN, CHN, and CEN decrease with neutral‐adjusted wind speed when wind speed is less than 5 m/s. CDN is constant over the range 5 m/s < U10N < 12 m/s, then increases with U10N when U10N > 12 m/s. In contrast, CHN and CEN exhibit no clear dependence on wind speed and are generally constant, with mean values of 0.96 × 10−3 and 1.2 × 10−3, respectively. This behavior of neutral exchange coefficients is consistent with the findings of previous studies. We also found that CDN under offshore winds is generally greater than that under onshore wind conditions, which is ascribed to the younger wind waves present due to the shorter fetch in the former case. However, this behavior is not exhibited by CHN or CEN. The original CD, CH, and CE values without MOST adjustment are also investigated to develop a new parameterization based on wind speed and stability. Three stability parameters are tested, including the bulk Richardson number, stability as defined in COARE 3.0, and a simplified Richardson number using the Charnock parameter. This new parameterization is free of MOST and the associated self‐correlation. Compared with previous studies and COARE 3.0 results, the new parameterization using the simplified Richardson number performs well, with an increased correlation coefficient and reduction of root‐mean‐square error and bias.

Investigation of thickness uniformity of thin metal films by using α-particle energy loss method and successive scanning measurements

The metal films are widely used in the Inertial Confinement Fusion (ICF) experiments to obtain the radiation opacity, and the accuracy of the measuring results mainly depends on the accuracy of the film thickness and thickness uniformity. The traditional used measuring methods all have various disadvantages, the optical method and stylus method cannot provide mass thickness which reflects the internal density distribution of the films, and the weighing method cannot provide the uniformity of the thickness distribution. This paper describes a new method which combines the α-particle energy loss (AEL) method and the successive scanning measurements to obtain the film thickness and thickness uniformity. The measuring system was partly installed in the vacuum chamber, and the relationship of chamber pressure and energy loss caused by the residual air in the vacuum chamber was studied for the source-to-detector distance ranging from 1 to 5 cm. The results show that the chamber pressure should be less than 10 Pa for the present measuring system. In the process of measurement, the energy spectrum of α-particles transmitted through each different measuring point were obtained, and then recorded automatically by a self-developed multi-channel analysis software. At the same time, the central channel numbers of the spectrum (CH) were also saved in a text form document. In order to realize the automation of data processing and represent the thickness uniformity visually in a graphic 3D plot, a software package was developed to convert the CH values into film thickness and thickness uniformity. The results obtained in this paper make the film thickness uniformity measurements more accurate and efficient in the ICF experiments.

Corneal biomechanics in normal Saudi individuals

PurposeThe aim of this study was to determine and relate corneal biomechanical metrics with demographic, tomographic and refractive data in healthy Saudi people. DesignProspective, cross-sectional, observational study. ParticipantsThe study included 215 normal Saudi adult individuals. MethodsCorneal hysteresis (CH) and corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg) and corneal-compensated intraocular pressure (IOPcc) were measured by ocular response analyzer. The central keratometry (CK), central corneal thickness (CCT), and anterior chamber depth (ACD) were measured using Pentacam system. The spherical equivalent of refraction (SER) was obtained by an Auto-refractometer. ResultsThe mean CH was 11.16±2.11, CRF was 11.07±2.31 and IOP was 15.12±3.5. Mean CK, ACD, CH and CRF were distinct among gender with the significant P values of 0.05, 0.006, 0.020, and 0.047 respectively. CRF was negatively correlated with ACD (r=−0.146, P=0.032). A positive correlation was found between CRF and SER (r=0.176, P=0.010), CCT (r=0.447, p=0.000) and CH (r=0.878 and p=0.000). CH was negatively correlated with IOPcc (−0.433, p=0.000). A positive correlation was found between CH and ACD (r=−0.14, p=0.044), SER (r=0.617, p=0.014), CCT (r=0.412, p=0.000) and IOPg (r=0.183, p=0.007). ConclusionThis study demonstrated a distinct difference among gender values of corneal hysteresis and corneal resistance factor being higher in female Saudi subjects. CH and CRF values were higher in Saudi subjects than values in other populations. This may suggest the presence of ethnic differences in ocular parameters and support the importance of establishing population norms for corneal biomechanical parameters.

Effects of large amounts of hydrogen on the fatigue crack growth behavior of torsional prestrained carbon steel

The effects of large amounts of hydrogen on the fatigue crack growth properties of torsional prestrained ferritic–pearlitic low-carbon steel were investigated. Hydrogen-precharged specimens were produced by conducting cathodic charge to the virgin material and to torsional prestrained JIS-S10C and JISS25C steels (hereafter S10C and S25C steels). Rotating bending fatigue tests were conducted in air at room temperature. Hydrogen content, CH, increased with torsional prestrain for both S10C and S25C steels; the CH of the torsional prestrained S25C steel precharged with hydrogen was lower than that of S10C at the same torsional prestrain. No clear difference between the maximum CH values of the torsional fractured S10C and S25C hydrogen-precharged steel specimens. With respect to crack initiation, there was no obvious difference between the uncharged and precharged specimens in spite of the large amount of CH induced by torsional prestrain. The acceleration of fatigue crack growth by hydrogen was the main cause of the decreased fatigue life. For the virgin material, hydrogen had no obvious effect on the fatigue crack growth rate. In contrast, for the torsional prestrained materials, the acceleration ratios, {(da/dN)H/(da/dN)U}, increased with the torsional prestrain and CH. However, {(da/dN)H/(da/dN)U} did not exceed the value of about 30, even when a large amount of hydrogen was charged (10.0 ? CH ? 30.3 mass ppm). A hydrogen content threshold was found; hydrogen content above this limit enhances the growth of the non-propagated crack, even for metals with lower hardness (HV < 200).

NOx Emissions Modeling and Uncertainty From Exhaust-Gas-Diluted Flames

Oxides of nitrogen (NOx) are pollutants emitted by combustion processes during power generation and transportation that are subject to increasingly stringent regulations due to their impact on human health and the environment. One NOx reduction technology being investigated for gas-turbine engines is exhaust-gas recirculation (EGR), either through external exhaust-gas recycling or staged combustion. In this study, the effects of different percentages of EGR on NOx production will be investigated for methane–air and propane–air flames at a selected adiabatic flame temperature of 1800 K. The variability and uncertainty of the results obtained by the gri-mech 3.0 (GRI), San-Diego 2005 (SD), and the CSE thermochemical mechanisms are assessed. It was found that key parameters associated with postflame NO emissions can vary up to 192% for peak CH values, 35% for thermal NO production rate, and 81% for flame speed, depending on the mechanism used for the simulation. A linear uncertainty analysis, including both kinetic and thermodynamic parameters, demonstrates that simulated postflame nitric oxide levels have uncertainties on the order of ±50–60%. The high variability of model predictions, and their relatively high associated uncertainties, motivates future experiments of NOx formation in exhaust-gas-diluted flames under engine-relevant conditions to improve and validate combustion and NOx design tools.

Spatio-temporal distribution of human lifespan in China.

Based on the data of latest three Chinese population censuses (1990–2010), four lifespan indicators were calculated: centenarians per one hundred thousand inhabitants (CH); longevity index (LI); the percentage of the population aged at least 80 years (ultra-octogenarian index, UOI) and life expectancy at birth (LEB). The spatio-temporal distributions of data at Chinese county level show that high-longevity areas (high values of CH and LI) and low-longevity areas (low CH and LI values) both exhibit clear non-uniformity of spatial distribution and relative immobility through time. Contrarily, the distribution of UOI and LEB shows a decline from the east to the west. The spatial autocorrelation analyses indicate less spatial dependency and several discontinuous clusters regions of high-CH and LI areas. The factors of temperature, topography and wet/dry climate lack of significant influence on CH and LI. It can be inferred that, in addition to genetic factor and living custom, some unique and long-term environmental effects may be related with high or low values of CH and LI.

Assessing subject‐related variations of the Ocular Response Analyzer parameter calculation

BackgroundThe aim was to study the relationships between the output parameters of the Ocular Response Analyzer (ORA) and those calculated from the raw ORA data and to ascertain the subject‐related variations of ORA parameter calculation procedures.MethodSix subjects were recruited for a prospective study. Up to 32 measurements by ORA were performed in series on the dominant eye of each subject. A relationship was examined between Goldmann‐correlated intraocular pressure values (IOPg) obtained from the standard ORA output and IOPg′ calculated from raw ORA data with a custom‐written procedure. The same analysis was carried out for the parameters of corneal hysteresis (CH and CH′). Data and statistical analysis included Epanechnikov kernel smoothing, orthogonal linear regression, hypothesis testing and bootstrap techniques.ResultsThe group average (mean ± standard deviation) IOPg and CH values were 11.6 ± 1.8-mmHg and 10.7 ± 1.7-mmHg, respectively. A strong correlation was found between IOPg and IOPg′ and also between CH and CH′ parameters. There was a significant (Behrens–Fisher test, p < 0.001) difference between subjects for both IOPg and CH calculations, in terms of the regression slope parameter.ConclusionsSubject‐related variations of ORA parameter calculation were demonstrated. This could indicate that currently employed estimators of IOP parameters include unreported algorithmic procedures that may lead to biased results.

Study of the correlation between hydrogenated amorphous silicon microstructure and crystalline silicon surface passivation in heterojunction solar cells

The properties of hydrogenated amorphous silicon (a‐Si:H) thin layers were studied by spectroscopic ellipsometry (SE) and Fourier transform infrared spectroscopy (FTIR) measurements to determine their effects on the surface passivation of crystalline silicon (c‐Si) in heterojunction solar cells. It was demonstrated that the high bulk quality of a‐Si:H layers with denser structures was not sufficient for the passivation of c‐Si surfaces in Silicon Heterojunction (SHJ) solar cells, in which the passivation performance is strongly governed by the total hydrogen content (CH) as a‐Si:H layers are ultra‐thin. High effective carrier lifetime and implied open‐circuit voltage (Voc,im), as well as low surface recombination velocity, were obtained at the appropriate CH values, and the optimal windows of CH and of the hydrogen content in the Si–H2 configuration (C2) were determined to be 5.0 ∼ 8.5 and 2.9 ∼ 6.8 at.%, respectively. For CH values higher than 8.5 at.%, the passivation effect was degraded due to the deteriorated bulk properties of the a‐Si:H layers. However, Voc,im decreased when CH was lower than 5.0 at.% because the number of H atoms was insufficient to saturate the dangling bonds at the a‐Si:H/c‐Si interface even though the a‐Si:H layers had dense microstructures.

Influence of different types of corneal laser refractive surgeries on corneal hysteresis and corneal resistance factor in myopic eyes

Background Refractive surgery has propelled itself forward to become widely performed surgical procedure nowadays.After the surgery, corneal biomechanics decreases lead to keratoconus and corneal ectasia.Doctors pay more attention to biomechanics changes after refractive surgeries. Objective This clinical study was to investigate the influence of different laser refractive surgeries on corneal biomechanics. Methods A prospective nonrandomized and controlled clinical study was designed.One hundred and sixty-four eyes of 82 patients with moderate myopia were enrolled.The patients were divided into sub-Bowman keratomileusis（SBK) group (60 eyes of 30 patients), laser in situ keratomileusis（LASIK) group (54 eyes of 27 patients) and laser subepithelial keratomileusis (LASEK) group（50 eyes of 25 patients), with the matched demography among the three groups.Corneal hysteresis (CH) and corneal resistance factor (CRF) were detected by ocular response analyzer (ORA) before and 1 week, 5 months after refractive surgery.The correlations between stromal ablation depth and postoperative changing values of CH or CRF were analyzed. Results Significant differences were found in CH and CRF at different time points in the three groups (Ftime=41.90, P=0.00; Ftime=49.65, P=0.00), and the CH and CRF values were significantly lower 1 week and 5 months after surgery than those before surgery (all at P=0.00). However, no significant difference of CH or CRF was seen at all time points among the three groups (Fgroup=2.17, P=0.08; Fgroup=2.67, P=0.07). No correlation was found between corneal ablation depth and CH in 1 week and 5 months after surgery (both at R2=0.000), however, weaker correlations were seen between corneal ablation depth and CRF 1 week and 5 months after surgery (Y=3.253+ 0.010X, R2=0.007; Y=1.073+ 0.021 X, R2= 0.004). Conclusions SBK, LASIK and LASEK lead to the change of corneal biomechanics by altering CH and CRF, they play the same influence on cornea.CRF appears to be an useful indicator in evaluating corneal biomechanical changes after laser refractive surgery. Key words: Cornea/physiology; Myopia/surgery; Elastic tissue; Biomechanics; Keratomileusis, laser in situ; Keratomileusis, laser subepithelial; Keratomileusis, sub-Bowman

Progressive hyperopic shift after radial keratotomy: possible causes

To describe possible causes of progressive hyperopia in patients who underwent radial keratotomy. The study enrolled 33 subjects who underwent radial keratotomy earlier in their lives, of them 15 controls (29 eyes, group 1) with no refractive error and 18 patients (35 eyes, group II) with progressive hyperopia. The number and type of keratotomy scars was determined during biomicroscopy. Biomechanical properties of the cornea were assessed by means of bidirectional applanation (Ocular Response Analyzer). Dynamic contour tonometry (Pascal) was also used for intraocular pressure (IOP) measurement. Evaluation of the optic nerve head and retina included standard automated perimetry (Humphrey Field Analyzer) and confocal scanning laser ophthalmoscopy with Heidelberg Retinal Tomograph (HRT III). Group II showed reliable signs of low corneal rigidity, namely reduction of CH and CRF values (by 2.4 and 1.6 mmHg respectively) and central corneal thickness (by 56 microns) as compared to the controls. Tonometry results differed inconsiderably showing a tendency toward hypertension in both groups. The interquartile range of IOP was 17.8 ÷ 22.4 mmHg in group II and 16.3 ÷ 20.6 mmHg in group I. Changes in retinal light sensitivity and optic nerve head parameters were more pronounced in the controls. Several reasons for lowering of corneal rigidity can be suggested: initial biomechanical parameters of the cornea, surgical interference, and age-related changes. We think that hyperopic shift results from the combination of low corneal rigidity and increased IOP, i.e. not the lamina cribrosa but the cornea becomes the target of ocular hypertension. Thus, patients with weakened corneal refraction after radial keratotomy are at risk for developing glaucoma in the late postoperative period.

Estimation of coefficients of consolidation and permeability via piezocone dissipation tests

Measured excess pore pressure dissipation responses always present a different trend from those theoretically expected. A simple hyperbolic equation for estimating the coefficient of consolidation [ch(Hyp)] was thus proposed based on the indirect fit between both responses. The method was applied to dissipation test data in the normally consolidated clay of Nakdong River Delta. The result indicates that ch(Hyp) values vary with the normalized excess pore pressure (U), showing different trends according to the patterns of both curves. The mean values estimated with four theoretical solutions vary within a difference of 200%, and are close to those of the consolidation tests. The coefficients of consolidation obtained using three conventional methods, which are based on the direct fits at U = 50% and between the early or late parts of both curves, lie within or out of the range of ch(Hyp). The coefficients of permeability estimated using the mean values of ch(Hyp) underestimate those of the laboratory permeability test and those of an empirical formula based on the piezocone sounding records.

Cone penetration-induced pore pressure distribution and dissipation

The excess pore water pressure distribution (u) induced by the penetration of a piezocone into clay and its dissipation behaviour have been investigated by laboratory model tests, theoretical analysis and numerical simulation. Based on the results of the tests and the analysis, a semi-theoretical method has been proposed to predict the piezocone penetration-induced pore pressure distribution in the radial direction from the shoulder of the cone. The method can consider the effect of the undrained shear strength (su), over-consolidation ratio (OCR) and rigidity index (Ir) of the soil. With a reliably predicted initial distribution of u and the measured curve of dissipation of pore water pressure at the shoulder of the cone (u2), the coefficient of consolidation of the soil in the horizontal direction (ch) can be back-fitted by analysis of the pore pressure dissipation. Comparing the back-fitted values of ch with the values directly estimated by a previously proposed method indicates that the previously proposed method can be used reliably to estimate ch values from non-standard dissipation curves (where u2 increases initially and then dissipates with time).

Mapping and candidate gene identification of loci induced by phytohormones in barley (Hordeum vulgare L.)

Phytohormones, a group of structurally unrelated small molecules are plant-signalling compounds that trigger induced resistance against certain pathogens and herbivores. The hormones jasmonic acid (JA), ABA, salicilic acid (SA) and ethylene (ET) are known to play major roles in regulating plant defence responses. In order to determine the changes in growth and in the chlorophyll content induced by the exogenous application of these elicitors, a set of DH lines of the Oregon-Wolfe Barley mapping population, previously screened to locate aphid resistant genes, was investigated. The aim of the current research was to map the induced defence genes and to reveal the relationship with aphid resistance. There were highly significant differences between controls and hormone treated plants in the aerial fresh and dry weights (AFW, ADW), the foliar area (FA) and the root dry weight (RDW). More than 15 JA and ET-induced lines exceeded the chlorophyll (Ch) values of their controls. Most of the plant traits were associated with the same genetic windows on chromosomes 3H, 5H and 7H in the controls and hormone treated plants. QTL(s) identified on chromosome 3H and 5H explained most of the variation of AFW, ADW, FA and RDW of controls and treated plants. QTL(s) located on chromosome 5H were associated with the variation of chlorophyll contents on JA-treated plants. The Ch in ET and ABA-treated plants was associated with two different regions on chromosome 7H. One of the latter genetic windows also explained the variation of RDW of ET- and ABA-treated plants. A sequence homology search was performed to derive the putative function of the genes linked to the QTLs. Several QTLs were identified located close to aphid resistance genes previously mapped. This is the first report of genes associated with hormone response in barley that could be involved with insect resistance. Those recombinant lines carrying the appropriate alleles could be useful for breeding barley to enlarge the genetic base of defence against stress.

Hyperbolic Fit Method for Interpretation of Piezocone Dissipation Tests

AbstractA simple hyperbolic equation is used to best fit measured piezocone pore pressure dissipation data. The same hyperbolic equation, albeit with slight differences in its coefficients, fits well the existing theoretical solutions/charts for piezocone dissipation response. Coefficient of consolidation ch can be conveniently expressed in terms of the hyperbolic parameters corresponding to the measured data and the existing solution charts. Field piezocone dissipation test data for Busan clay is successfully fitted using the provided hyperbolic equation. The ch values thus determined over a range of degree of consolidation (10–90%) compare well with ch values obtained by the traditional direct use of the same existing theoretical solutions or charts.

Working Hypothesis, Special Laboratory Tests, Working Tools, Analysis of the Monitoring of a Pilot Embankment Built on Soft Clay in Santos with Wick Drains and its Application to the Final Design

Routine in-situ and laboratory investigations carried out for the basic design failed to provide reliable values for compressibility and consolidation parameters of soft clay layers at the site of a terminal to be built in Santos. A pilot embankment was designed and built divided in three equal areas, two with wick drains in a square mesh at spacings of 1.2 m and 2.4 m respectively and one with no drain. The basic working hypothesis adopted by the authors was that, in the field, primary and secondary consolidation occur simultaneously. High quality standard and special (long term and relaxation) oedometer tests provided reliable values of Cc , Cr and σ’p and the OCR value of 2.1 as equivalent to the end of secondary consolidation allowing to estimate the total primary and secondary compressions of one of the most compressible layers (layer 6). No of the shelf tool is available to backanalyze the measured compression of a soft clay layer based on the adopted hypothesis. The first tool tested, the ε vs. log(σ’v) Bjerrum type abacus with lines of equal values built from the oedometer tests results, proved to be non applicable. The second tool tested, the same type of abacus extrapolated from the first one for the field conditions through Taylor and Merchant’s theory also proved to be non applicable. Both the third tool tested, the fitting of a theoretical Taylor and Merchant type curve to the measured compression curve in the area with no drain and the fourth tool tested, the fitting of a theoretical curve obtained through a method tailored by the authors designated “Primary Barron + secondary pseudo Taylor and Merchant” to the measured compression curves in the areas with wickdrains proved to provide excellent conformity of the theoretical and measured curves. The cv and ch field values thus obtained are of the same order of magnitude as the laboratory values and show the same trend to decrease when the effective stress increases, contradicting the current creed based on backanalysis through Asaoka’s method, i.e. considering that secondary consolidation only starts after primary consolidations ends, that field cv and ch values are commonly 10 to 100 times higher than laboratory values. Based on their results the authors conclude that the excellent conformity of the theoretical and the measured curves obtained with the working hypothesis they adopted, the results of the laboratory tests they performed and the tools they used for the back-analysis, leads to the conclusion that the working hypothesis, the laboratory tests and the tools proved to be very efficient and trustworthy in leading to reliable compressibility and consolidation parameters of the soft clay, and will be equally efficient and trustworthy when used for the final design of the improvement of the foundation soft clay layer

Accurate measurement of small heteronuclear coupling constants from pure-phase α/ β HSQMBC cross-peaks

A simple proton-selective α/ β-HSQMBC experiment is proposed for the accurate measurement of long-range proton–carbon coupling constants ( n J CH) in small molecules without need for an individualized and time-consuming post-processing fitting procedure. The method acquires two pure-phase In-phase (IP) and Anti-phase (AP) multiplets completely free of any phase distortion due to the absence of J HH evolution. Accurate n J CH values can be directly measured analyzing the relative displacement of the resulting IPAP cross-peaks. Discussion about signal intensity dependence and cross-talk is made for a range of experimental conditions. The robustness of the method is evaluated by comparing the n J CH value measured from the analysis of the three available IP, AP and IPAP multiplet patterns. Multiple-frequency and region-selective versions of the method can also be efficiently recorded provided that excited protons are not mutually coupled.

Corneal biomechanical properties measured with the Ocular Response Analyser in a myopic population

To explore the possible association between myopia and corneal biomechanical properties in a Caucasian population, and the correlations between the properties of right and left eyes. Corneal hysteresis (CH) and corneal resistance factor (CRF) were measured using the Ocular Response Analyser (ORA) in both eyes of 95 normal adult subjects aged between 19 and 48 years. The spherical equivalent refractive errors of the participants ranged from 0.25 to -14.00 D. The mean CH and CRF values for the right and left eyes were recorded for each subject. CH and CRF data were compared between different refractive groups. CH was found to be slightly lower in high myopes (>-6.00 D, mean CH 10.0 ± 1.2 mmHg) in comparison to moderate myopes (>-3.00 to -6.00 D, 10.1 ± 1.4 mmHg) and emmetropes and low myopes (+0.25 to -2.75 D, 10.9 ± 1.5 mmHg). The decrease in CH with the degree of myopia was about 0.13 mmHg per D or roughly 1% per D (r(2) = 0.084, p < 0.001). Inter-subject variations were much greater than any systematic changes. CRF was not correlated with refractive error (r(2) = 0.001, p = 0.66). Although the refractive error was highly correlated between the two eyes (r(2) = 0.89, p < 0.001), CH and CRF showed a lower inter-ocular correlation (r(2) = 0.68, p < 0.001 and r(2) = 0.77, p < 0.001 respectively). These findings may indicate that the viscoelastic properties of the cornea are altered to a minor extent in myopia. However, in this normal population, any overall systematic changes in CH and CRF with refractive error were small in comparison with the considerable inter-subject scatter at any level of refraction.

Serum lipid profile in non-pregnant and prenant Hausa-Fulani women at second and third trimester of pregnancy in Kura local government area, Kano State, Nigeria

Serum levels of total cholesterol (TC), high density lipoprotein cholesterol (HDL-CH) and low density lipoprotein cholesterol (LDL-CH) concentrations were determined in two hundred and fifty (250) apparently healthy females of child bearing age ( non pregnant, 127 and pregnant 123) who attended the antenatal and other clinics at Kura Comprehensive Health Centre, Kano State from August to December 2005. Body weight and height of each subject were taken to calculate body mass index (BMI). Mean serum TC, HDL-CH and BMI values were found to be higher in pregnant than in non pregnant subjects. When the pregnant subjects were classified on the basis of gestational age, 35.0% were in second trimester and 65.0% were in the third trimester. Mean serum TC, HDL- CH and LDL- CH values were significantly higher (p< 0.05) in second trimester subjects than third trimester subjects. Though a preliminary study, the result of this work will contribute in unraveling the serum lipid profile among pregnant and non pregnant Hausa - Fulani women in Northern Nigeria. Key word: serum lipoproteins, pregnant women, Hausa-Fulani, Northern Nigeria

Partition Coefficients of Organic Contaminants with Carbohydrates

In view of the current lack of reliable partition coefficients for organic compounds with carbohydrates (K(ch)), carefully measured values with cellulose and starch, the two major forms of carbohydrates, are provided for a wide range of compounds: short-chain chlorinated hydrocarbons, halogenated benzenes, alkyl benzenes, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, and organochlorine pesticides. To ensure the accuracy of the K(ch) data, solute concentrations in both water and carbohydrate phases are measured by direct solvent extraction of the samples. For a given compound, the observed partition coefficient with cellulose (K(cl)) is virtually the same as that with starch (K(st)). This finding expedites the evaluation of organic contamination with different forms of carbohydrates. The presently determined K(ch) values of 13 PAHs are substantially lower (by 3-66 times) than the literature data; the latter are suspect as they were obtained with (i) presumably impure carbohydrate samples or (ii) indirectly measured equilibrium solute concentrations in carbohydrate and water phases. Although the K(ch) values are generally considerably lower than the respective K(ow) (octanol-water) or K(lipid) (lipid-water), accurate K(ch) data are duly required to accurately estimate the contamination of carbohydrates by organic compounds because of the abundance of carbohydrates over lipids in crops and plants. To overcome the current lack of reliable K(ch) data for organic compounds, a close correlation of log K(ch) with log K(ow) has been established for predicting the unavailable K(ch) data for low-polarity compounds.