Biomedical subjects

Q Y Cai

Publications and source records attributed to Q Y Cai.

6 recordsLinked to original sources

PubMed2001

A wireless, remote query ammonia sensor.

This paper presents a wireless, remote query ammonia sensor comprised of a free-standing magnetoelastic thick-film coated with a polymer, poly(acrylic acid-co-isooctylacrylate), that changes mass in response to atmospheric ammonia concentration. The mass of the polymer layer modulates the resonant frequency the ferromagnetic magnetoelastic substrate, hence by monitoring the frequency response of the sensor, atmospheric NH3 concentration can be determined remotely, without the need for physical connections to the sensor or specific alignment requirements. The effect of copolymer composition, polymer film thickness, and relative humidity level (RH) on the sensitivity of the sensor were investigated. The sensor linearly tracks ammonia concentration below 0.8 vol.%, and tracks higher concentrations logarithmically; within the linear calibration range, a 0.02 vol.% change in NH3 concentration can be detected.

Acrylates↗

PubMed2000

A remote query magnetoelastic pH sensor.

A remote query magnetoelastic pH sensor comprised of a magnetoelastic thick-film coated with a mass-changing pH-responsive polymer is described. In response to a magnetic query field the magnetoelastic sensor mechanically vibrates at a characteristic frequency that is inversely dependent upon the mass of the attached polymer layer. As the magnetoelastic sensor is magnetostrictive the mechanical vibrations of the sensor launch magnetic flux that can be detected remotely from the sensor using a pickup coil. The pH responsive copolymer is synthesized from 20 mol% of acrylic acid and 80 mol% of iso-octyl acrylate and then deposited onto a magnetoelastic film by dip-coating. For a 1 micrometer polymer coating upon a 30 micrometer thick Metglas [The Metglas alloys are a registered trademark of Honeywell Corporation. For product information see: http://www.electronicmaterials.com:80/businesses/sem/amorph/page5_1_2.htm.] alloy 2826MB magnetoelastic film between pH 5 and 9 the change in resonant frequency is linear, approximately 285 Hz/pH or 0.6%/pH. The addition of 10 mmol/l of KCl to the test solution decreases the sensitivity of the polymer approximately 4%.

Acrylates↗

PubMed2000

A wireless, remote query magnetoelastic CO2 sensor.

This paper presents a wireless, passive, remote query CO2 sensor comprising a ribbon-like magnetoelastic thick-film coated with a mass-changing CO2 responsive polymer synthesized from acrylamide and isooctylacrylate. In response to a magnetic field impulse, the magnetostrictive magnetoelastic sensor vibrates at a characteristic resonant frequency that is inversely dependent upon the mass of the attached CO2 responsive polymer. The mechanical vibrations of the magnetostrictive sensor launch magnetic flux, which can be detected remotely using a pickup coil. By monitoring the resonant frequency of the passive sensor, the atmospheric CO2 concentration can be determined without the need for physical connections to the sensor or specific alignment requirements. The effect of humidity and the CO2 responsive copolymer composition on the measurement sensitivity are reported. Greatest sensitivity is achieved with a polymer comprising a 1:1 mole ratio of acrylamide to isooctyl acrylate. A 0.7% change in atmospheric CO2 concentration can be detected for a 20 microns thick polymer coated sensor.

Acrylamide↗

PubMed1996

Antioxidant status in persons with and without senile lens changes.

Biochemical evidence on lens culture suggests that antioxidant nutrients can protect lens against peroxidation caused by radiation. A case-control study was carried out on 262 middle aged (45-54) and aged (55-64) subjects. The relationship between biochemical markers of antioxidant status and senile lens changes (including cataract) was examined in 131 subjects with senile lens changes and 131 control subjects with clear lens. Antioxidant status was measured using plasma and erythrocyte glutathione peroxidase, erythrocyte superoxide dismutase and catalase activity and plasma levels of vitamin E and vitamin A. Subjects were grouped by age and sex. The results were as follows: (1) The subjects with lens changes tended to have lower plasma levels of vitamin E and vitamin A, lower activity of several antioxidant enzymes and higher level of MDA. (2) The subjects with senile lens changes had significantly lower erythrocyte glutathione peroxidase level. (3) In the middle-aged group, subjects with senile lens changes were observed to have lower erythrocyte and plasma glutathione peroxidase level than those without senile lens changes. The results suggest that appropriate amount of antioxidant nutrients might be expected to prevent or retard the process of lens changes.

Aging↗

PubMed1994

Biochemical and morphological changes in the lenses of selenium and/or vitamin E deficient rats.

The activities of glutathione peroxidase (GSH-Px), glutathione reductase (GSSG-R), superoxide dismutase (SOD) and the contents of malondialdehyde (MDA) and free radicals were measured, and the morphological changes were observed in the lens of control rats, selenium-deficient (SeD) and/or vitamin E deficient (VED) rats. The activities of GSH-Px in the lens of SeD rats decreased significantly. The GSH-Px activities of lens were positively related to erythrocytes selenium level. There was a free radical at g = 2.0015 in the rat lens of all groups, but the content of free radicals in the lens of SeD group was significantly higher than that of the control group. The free radical content of lens was negatively related to erythrocytes selenium level, as well as the GSH-Px activities in the lens. In vitro, ultraviolet radiation caused the generation of another kind of free radical (g = 2.0097) in the lens of all groups, but the amount of the free radical in the lens of the SeD group was also significantly higher than that of the control group. The activities of SOD and GSSG-R in VED rat lens were significantly decreased. The amount of MDA in the lens of SeD and/or VED rats were significantly increased. The results showed that the decrease of antioxidative capability in the lenses of SeD and/or VED rats accelerated the lipid peroxidation and generation of free radicals. Although only early morphological changes in SeD and/or VED rat lens were observed, it is considered that selenium and vitamin E deficiency may be involved in the occurrence of cataract.

Animals↗

PubMed1994

[Birth weight prediction by B-type ultrasonic measurement of fetal transverse cerebellar diameter].

The fetal transverse cerebellar diameter (CD), biparietal diameter(BPD), abdominal circumference (AC) and femur length(FL) were measured by B-type ultrasonography on 222 normal pregnant women with one week before the expected date of confinement (EDC) and their correlations with birth weight of newborns were computerized. Single factorial analyses showed the best correlation was between CD and birth weight (R = 0.913 4) where as the R value for birth weight and AC, BPD, FL was 0.739 5, 0.612 5, 0.347 6 respectively. The F value of CD on stepwise regression analysis was the highest (F = 1001.95) while that of AC and BPD was 4.55, 4.36 respectively (P < 0.05). Then the regression equations of single double and triple factors were established. It was confirmed by clinical findings that the equation of log(BW) = 2,8844 + 0.01416 x CD was the most reliable one in predicting the birth weight. The error rate was less than 10% in 96% of the newborns.

Anthropometry↗