Oxygen vacancy-enriched Zn2SnO4 for aliphatic alcohol sensing and enhanced selectivity towards n-butanol

The sensitive detection of toxic flammable volatile organics using low cost efficient sensors is important for ensuring both indoor and outdoor safety. It is essential for chemical sensors to exhibit a significantly stronger response to target analytes compared to equivalent amounts of analogous competing chemicals. In line with this importance, current work evaluated the performance of Zn2SnO4, a n-type semiconducting metal oxide, for sensing n-butanol in comparison to methanol, ethanol, and propanol vapours. These vapours fall within the category of aliphatic alcohols but vary in characteristics such as molecular weight, vapour pressure, volatility, and diffusivity. In this work we have explored the sensor's performance by adjusting the operating temperature over the range of 225-300 °C while detecting 1000 ppm of each of these vapours. Efforts were made to establish a correlation between the sensor's responses with the interactions of these vapours on the sensor's surface. Prior to assessing the sensing characteristics of the solid-state-route-derived Zn2SnO4, its structural characteristics, including phase purity, crystalline structure, bonding patterns, morphology, and defect characteristics, were studied. This comprehensive analysis sheds light on the potential of Zn2SnO4 as an effective sensor for detecting n-butanol.

Probing the p-type Chemiresistive Response of NiFe2 O4 Nanoparticles for Potential Utilization as Ethanol Sensor

Detection of gas molecules and volatile organic compounds (VOCs) using efficient, low cost sensors has fetched significant attention in environmental monitoring, safety measures and medical diagnosis. In the present work, nickel ferrite (NFO) nanoparticles are explored as p-type semiconducting metal oxide (SMO) sensor for detection of five different organic vapors namely methanol, ethanol, n-propanol, iso-propanol and acetone which often cause severe damage to human body under prolonged exposure. The sensing studies in presence of the aforementioned five vapors are carried out by varying the sensor operating temperature (225-300 °C) and vapor concentrations (10-1000 ppm). Developed NFO sensor demonstrated best performance in terms of sensing (~10 ppm), response time (<10 s), excellent repeatability and selectivity towards ethanol among all other considered gas species. The repeatability of the sensor response is verified and the underlying reasons for the variation in the response of NFO sensor due to the change of operating temperature, analyte type and concentrations has been discussed. The synthesis of NFO through auto combustion method and study on their formation behaviour, oxygen vacancy evolution, band gap calculation, crystalline nature as well as microstructural features provides here the comprehensive information about the potential application of NFO nanoparticles as gas sensor.

Bacterial vaginosis in early pregnancy and adverse pregnancy outcome

OBJECTIVE

To assess the prevalence of bacterial vaginosis (BV) in asymptomatic pregnant women and its association with preterm birth (PTB) and premature rupture of membranes (PROM).

METHODS

In a cohort study 1,006 pregnant women between 16-28 weeks' gestation were screened for BV (Nugent's criteria) and for lower genital tract infection. Women were followed to confirm pregnancy outcome. Data were analyzed using STATA software. Univariate and multivariate methods were used to investigate the association between bacterial vaginosis and adverse pregnancy outcome.

RESULTS

Prevalence of BV was 11.53%. Baseline characteristics were similar for both groups, 6.8% women were lost to follow-up. Incidence of PTB was higher in BV positive women compared to BV negative women (p = 0.001). On multiple logistic regression (MLR), BV was associated with an increased risk of PTB (p = 0.001) and PROM (p = 0.001), other correlates being previous PTB (p = 0.003) and the presence of enteropharyangeal organisms in vagina (p = 0.03). BV accounted for 82.53% of the attributable risk for PTB.

CONCLUSION

Presence of BV in early pregnancy is associated with an increased risk of PTB and PROM. Multicentric interventional study is recommended.

Identification of calmodulin-dependent protein kinase III and its major Mr 100,000 substrate in mammalian tissues

A major substrate, Mr 100,00 (100 kDa), for a Ca2+/calmodulin (CaM)-dependent protein kinase found in many mammalian tissues has been purified from rat pancreas. The purified substrate was used to identify and partially purify a CaM-dependent protein kinase (CaM kinase III) from rat pancreas. The physical properties and substrate specificity of CaM kinase III were distinct from those of all known CaM-dependent protein kinases. Only CaM kinase III was able to phosphorylate the 100-kDa protein; synapsin I, phosphorylase b, myosin light chain, and histone were poor substrates for this enzyme. Polyclonal antibodies, raised against the purified 100-kDa protein, recognized the protein in a variety of mammalian tissues and cell lines. Immunoassay revealed that the 100-kDa protein made up 0.3-1.7% of the total cytosolic protein in these samples. Analysis of CaM kinase III revealed that the enzyme had a similar widespread tissue distribution. These results demonstrate the existence of a fifth CaM-dependent protein phosphorylation system present in high levels in animal cells.

Insulin-induced enhancement of uptake of noradrenaline in atrial strips

1 Addition of insulin to the organ bath increased the force of contraction of guinea-pig left atrial strips driven electrically at 1 Hz. 2 The positive inotropic response to insulin remained unaltered in atria depleted of catecholamine or when beta-adrenoceptors were blocked by addition of propranolol to the organ bath. 3 The response os isolated atria to noradrenaline was significantly reduced in the presence of insulin. 4 Insulin affected neither the calcium accumulating abilities of the heart sarcolemma, mitochondria or microsomes, nor the cyclic adenosine 3',5'-monophosphate (cyclic-AMP)-protein kinase-induced stimulation of microsomal calcium uptake. 5 Addition of insulin to the organ bath enhanced significantly the ability of the cardiac tissue to take up [3H]-noradrenaline as well as [3H]-metaraminol. The activities of monoamine oxidase and catechol-O-methyl transferase were not changed after addition of insulin to homogenates of the heart. 6 The ability of insulin to facilitate uptake of noradrenaline would be expected to cause a decrease in the amount of the amine reaching the receptors, thus leading to a diminished response to this amine. This may explain, at least in part, insulin-induced subsensitivity to noradrenaline. 7 This view is supported by the observation that after blockade of amine uptake by destruction of nerve terminals, insulin failed to reduce the positive inotropic response to noradrenaline.

Effect of dopamine on renal blood flow of baboon in endotoxin shock

Renal vasodilation observed in canine endotoxemia did not occur during endotoxin shock in the baboon: in fact, renal artery blood flow was markedly reduced. Infusion of dopamine in the baboon restored the renal artery blood flow.

cAMP activity and isoproterenol-induced myocardial injury in rats

Isoproterenol-induced myocardial necrosis (ISO-MN) was obviated by the cardioselective beta-blocker, practolol, suggesting that ISO-MN is caused by specific activation of myocardial beta-adrenergic receptors. Because cAMP is the "second messenger" in such activation, enhanced activity of cAMP should aggravate ISO-MN. Pretreatment of rats with bretylium in various amounts, elicited no ill effects but enhanced the effects of ISO on the cAMP activity and also intensified the ISO-induced structural changes in the myocardium.

Modification by prostaglandin E 2 (PGE 2 ) of the response of guinea-pig isolated vasa deferentia and atria to adrenergic stimuli

1. Prostaglandin E(2) (PGE(2)) exerted positive cardiostimulant effects on isolated guinea-pig atria. The response was not altered by treatment of the animal with reserpine or by addition of propranolol to the organ bath. These results suggest that the cardiostimulatory actions of PGE(2) are not mediated through the release of catecholamines or stimulation of adrenoceptors.2. On the electrically driven atria, PGE(2) consistently exerted a cardiostimulant action which was not appreciably altered by changes in calcium ion in the bathing medium. PGE(2) showed no effect on the transport of calcium by the fragments of heart sarcoplasmic reticulum.3. PGE(2) reduced the responses to both noradrenaline and tyramine in the isolated atria. The shifted dose-response curve was not parallel to the original.4. PGE(2) increased the contractor response of the isolated vas deferens to nerve stimulation or to direct electrical stimulation.5. PGE(2) antagonized the increase caused by noradrenaline in contractor response of isolated vas deferens to direct electrical stimulation, whereas it affected the potentiation by noradrenaline differently when the vas deferens was contracting in response to nerve stimulation. In low concentration it inhibited and in large concentrations, it slightly enhanced the potentiation by catecholamine.6. It is concluded that PGE(2) has actions on multiple sites. It has post-junctional as well as pre-junctional effects on adrenergic neurones.

Effect of reserpine on the activity of adrenal enzymes involved in the synthesis of adrenaline

1. After administration of reserpine to rats, the tyrosine hydroxylase (TH) and phenylethanolamine-N-methyl transferase (PNMT) activity in their adrenal glands was found to be increased under in vitro conditions.2. The increase in TH activity occurred at 12-18 h after reserpine whereas the PNMT activity increased at 30 hours. Unlike the TH, the increase in PNMT activity did not appear to be neuronally mediated since ganglion blockade by chlorisondamine failed to antagonize the reserpine-induced increase in PNMT activity. The increase in PNMT activity may be a response to increased utilization of catecholamines.3. Hypophysectomy resulted in a diminution of the activities of both enzymes; the activity of TH, but not of PNMT, could be partially restored by reserpine. ACTH restored the activities of both enzymes almost to normal.4. The differential effect of reserpine suggests that the activities of these two enzymes are controlled by different mechanisms.

Effect of chronic administration of nicotine on the concentrations of adrenal enzymes involved in the synthesis and metabolism of adrenaline

Chronic administration of nicotine caused an increase in tyrosine hydroxylase and catecholamine concentrations in rat adrenals, but failed to affect adrenal monoamine oxidase, catechol-O-methyl transferase or phenylethanol-amine N-methyl transferase activities.

Noradrenaline and tyramine action on isolated atrial muscle of endotoxin-treated guinea-pigs

1. Isolated left-atrial strips of guinea-pigs were driven electrically at a constant rate and log-concentration curves were determined for the positive inotropic effect of noradrenaline and tyramine.2. The atrial tissue from endotoxin-treated animals had a reduced sensitivity to noradrenaline and tyramine.3. After endotoxin, the sensitizing effect of cocaine on the response to noradrenaline was normal but accumulation of (3)H-noradrenaline in nerve terminals was markedly reduced.4. Atrial tissue of endotoxin-treated guinea-pigs responded normally to stretch.

Effects of chronic administration of nicotine on storage and synthesis of noradrenaline in rat brain

1. Chronic administration of nicotine (0.5 mg/kg, subcutaneously four times a day, 5 days a week, for 6 weeks) did not affect the growth rate and water intake in rats. In these animals food intake was normal for the first 5 weeks, but was significantly increased during the sixth week of treatment.2. Nicotine administration increased the blood pressure of rats from 120 mm Hg to 151 mm Hg.3. The concentrations of endogenous noradrenaline, dopamine, 5-hydroxytryptamine and acetylcholine in the brain remained unaltered. However, chronic treatment with nicotine increased the turnover rate of noradrenaline. Initial accumulation of (3)H-noradrenaline was also significantly increased.4. It is concluded from these studies that changes in the turnover of cerebral noradrenaline caused by chronic administration rather than changes in the concentration of noradrenaline may be an important factor in nicotine-induced behavioural changes.

Role of adrenal hormones in the synthesis of noradrenaline in cardiac sympathetic neurones

1. Adrenalectomy or adrenal demedullation affected neither the levels of endogenous catecholamines in the rat heart nor the accumulation of (3)H-noradrenaline 1 hr after its intravenous administration.2. Twenty-four hours after intravenous administration of labelled amine, however, its retention was markedly reduced in the heart of adrenalectomized or demedullated rats. Ganglionic blockade prevented this reduction.3. Rate calculations from the decline of catecholamine levels after blockade of synthesis with alpha-methyl-tyrosine showed that cardiac synthesis of noradrenaline increased about four-fold after demedullation and about three-fold after adrenalectomy. This increase in synthesis may compensate for the loss of circulating catecholamines.4. There was no change in catechol-o-methyl-transferase activity, but monoamine oxidase activity was increased in the homogenates of the heart of adrenalectomized and demedullated rats. The increase in the cardiac monoamine oxidase activity was markedly greater in the adrenalectomized rats than in the demedullated rats.5. It is suggested that adrenal cortex insufficiency may modulate the rate of synthesis of noradrenaline and monoamine oxidase activity in cardiac sympathetic neurones.

Factors involved in maintenance of cardiac catecholamine content: relative importance of synthesis and re-uptake

1. When animals were exposed to a temperature of 4 degrees C for 6 hr, endogenous catecholamines remained unaltered or reduced slightly depending upon the strain of rats used. In contrast, labelled noradrenaline declined rapidly, but the decline was inhibited when animals were pretreated with monoamine oxidase inhibitors.2. Increased sympathetic nervous activity associated with cold resulted in a four-fold increase in rate of synthesis of noradrenaline.3. Reduction in endogenous and labelled catecholamine levels associated with cold was exaggerated by pretreatment with cocaine, imipramine or phenoxybenzamine-drugs known to inhibit the uptake of noradrenaline into the nerve terminal.4. Cocaine and imipramine in higher doses inhibited the release of both endogenous and labelled noradrenaline, suggesting a dual action: in small doses they increased the depletion of catecholamines by blocking the reincorporation, while in higher doses they inhibited the release of noradrenaline.5. It is concluded that, under normal conditions, the re-uptake mechanism may not play a significant role in the maintenance of normal cardiac catecholamine levels and that such levels are maintained by synthesis alone. However, when the heart is subjected to high impulse nerve activity, synthesis is not sufficiently accelerated to compensate for impulse-induced massive release and may require the support of an additional mechanism, such as the partial reincorporation of released transmitter. In fact, the re-uptake mechanism is enhanced during high impulse activity.