Switching of ferroelectric liquid crystal doped with cetyltrimethylammonium bromide-assisted CdS nanostructures.

Large scale high yield cadmium sulfide (CdS) nanowires with uniform diameter were synthesized using a rapid and simple solvo-chemical and hydrothermal route assisted by the surfactant cetyltrimethylammonium bromide (CTAB). Unique CdS nanowires of different morphologies could be selectively produced by only varying the concentration of CTAB in the reaction system with cadmium acetate, sulfur powder and ethylenediamine. We obtained CdS nanowires with diameters of 64-65 nm and lengths of up to several micrometers. A comparative study of the optical properties of ferroelectric liquid crystal (FLC) Felix-017/100 doped with 1% of CdS nanowires was performed. Response times of the order of from 160 to 180 µs, rotational viscosities of the order of from 5000 to 3000 mN s m(-2) and polarizations of the order of from 10 to 70 nC cm(-2) were measured. We also observed an anti-ferroelectric to ferroelectric transition for CdS doped FLC instead of the ferroelectric to paraelectric transition for pure FLC.

Voltage induced anomalous conductance switching behaviour in nematic liquid crystal-multiwalled carbon nanotube composite.

Investigations on the voltage induced conductance switching behavior in the nematic liquid crystal-multiwalled carbon nanotube composite have performed. We have found that, the system formed electrical conduction pathways with increasing voltages. Anomalous conductance switching took place at a certain threshold voltage. Percolation threshold voltage depends on the frequencies of the measuring electric field. We have made an analogy between concentration dependent percolation and voltage induced percolation. A two dimensional (2D) renormalization model calculation reveals that if the CNTs form a 2D network then percolation threshold concentration (p(c)) should be 0.768. After careful analysis we have found that voltage analogy of percolation threshold concentration in our system is also very close to the above value. The connectivity exponent (beta) for 2D site percolation agrees well with our proposed voltage induced percolation connectivity exponent. Which gives a glimpse that voltage induced percolating network may forms a two dimensional network in this particular system.

Influence of age and obesity on serum estradiol, estrone, and sex hormone binding globulin concentrations following oral estrogen administration in postmenopausal women.

OBJECTIVE: Hormone therapy (HT) increases the risk of venous thrombosis and stroke. Risk of venous thrombosis and stroke is higher in older, overweight, and obese women using HT. However, the impact of age and obesity on estrogen concentrations among HT users is not well defined. METHOD: We measured serum levels of estrone, total and free estradiol, and SHBG in 180 postmenopausal women participating in the Estrogen in the Prevention of Atherosclerosis Trial (EPAT), 91 receiving estradiol therapy (ET) and 89 taking placebo, every 6 months over 2 yr. Mean on-trial levels of estrogens and SHBG were compared across age, body mass index (BMI), and waist to hip ratio categories among ET users and placebo separately. RESULTS: Among the ET users, total (P = 0.01) and free estradiol (P = 0.002) were significantly directly associated with BMI adjusted for age. SHBG was inversely related to waist to hip ratio adjusted for age (P = 0.005). Age was not associated with any of the estrogen or SHBG concentrations in ET or placebo groups. BMI was positively associated with estrone concentrations among older but not younger ET users (P for interaction = 0.03). CONCLUSION: Overweight and obese women using ET attain greater concentrations of estrogen compared to women with normal BMI, whereas ET users with abdominal obesity attain lower SHBG levels. Obese older women using ET have the highest concentration of estrone. It may be useful to consider age and obesity when prescribing HT to minimize the risk of venous thrombosis or stroke in postmenopausal women. Further research regarding relationships among circulating hormone levels and risk for these conditions is required to substantiate this conclusion.

Pharmacokinetics of dehydroepiandrosterone and its metabolites after long-term oral dehydroepiandrosterone treatment in postmenopausal women.

OBJECTIVE: Some postmenopausal women use over-the-counter dehydroepiandrosterone because of its purported beneficial effects. Although without major inherent androgenic activity, it is metabolized to potent androgens and estrogens. We investigated the pharmacokinetics of dehydroepiandrosterone and its relevant metabolites after prolonged treatment of postmenopausal women with 25 mg/d of dehydroepiandrosterone. METHODS: Twenty healthy postmenopausal women were randomized to either 25 mg/d of dehydroepiandrosterone or placebo for 6 months. Frequent blood samples were obtained over 24 hours on day 1 and after 3 and 6 months. RESULTS: Mean baseline androgen levels at day 1 and month 3 in the treated group (seven evaluable women) were the following: dehydroepiandrosterone, 1.82 and 3.56 ng/mL; dehydroepiandrosterone sulfate, 0.96 and 3.37 microg/mL; 5-androstene-3beta,17beta-diol, 0.32 and 0.66 ng/mL; androstenedione, 0.50 and 0.86 ng/mL; testosterone, 17.9 and 28.7 ng/dL; dihydrotestosterone, 6.91 and 17.4 ng/dL; and 3alpha-androstanediol glucuronide, 2.66 and 10.7 ng/mL, respectively; these increases were significant. Small changes (-6% to 16%) were observed from month 3 to month 6. Nonsignificant increases were observed in baseline estrone and estradiol levels and in Cmax and AUC0-24h values for the androgens and estrogens from day 1 to months 3 and 6 of treatment. Sex hormone-binding globulin levels were unchanged, but free testosterone increased significantly from day 1 to month 3. Baseline hormone levels did not increase in the placebo group (six evaluable women). Changes in baseline values over time differed significantly between the groups for all hormones except estrone and estradiol. CONCLUSIONS: In postmenopausal women treated orally with a commonly available dose of dehydroepiandrosterone, the daily exposure (AUC) of dehydroepiandrosterone and its principal androgenic metabolites was found to be similar during 6 months of treatment despite increased serum baseline concentrations of these androgens.

Hierarchical assembly of carbon nanotubes-liquid crystal nanocomposite.

Fabrication of liquid crystalline (LC) nanomaterials in an aligned pattern along the multiwalled carbon nanotubes (CNT) has been reported here. The nanocomposite was prepared by sonicating esterified CNTs and the ferroelectric liquid crystal (FLC) in chloroform. The nanohybrid shish kebab (NHSK) like pattern was observed in SEM analysis. The nanocomposite materials were characterized by Fourier transform infrared spectroscopy (FTIR), polarizing optical microscopy and electron microscopy. The DC and AC electrical properties of the composite materials were investigated. The DC conductivity of the nanocomposite increased by 2 order from the FLC materials and AC relaxation has been observed, in the nanocomposite, which was totally absent in the FLC materials.

Effects of liquid crystal environment on the spectroscopic and photophysical properties of well-known reacting systems 2,3-dimethylindole (DMI) and 9-cyanoanthracene (9CNA).

Electrochemical and steady-state and time-resolved spectroscopic studies on a disubstituted indole, 2,3-dimethylindole (DMI), and well-known electron acceptor 9-cyanoanthracene (9CNA) in liquid crystal (LC) 4-(n- pentyl)-4'-cyanobiphenyl (5CB) environment demonstrate entirely different spectroscopic and photophysical behaviors from those observed earlier by our research group with the same reacting systems in isotropic media n-heptane and acetonitrile (ACN). From the UV-vis absorption spectral measurements of the donor DMI in the presence of the acceptor 9CNA in liquid crystal medium (in 5CB) in various temperatures above the nematic-isotropic phase transition from 308 to 313 K (pseudo-ordered domain), it was observed that the lower energy lying absorption band of DMI situates in a longer wavelength region than the corresponding band observed in isotropic medium n-heptane or ACN. The possibility of the photochromic effect is discussed. In this band, the degree of mixing of the two closely spaced electronic states (1)L(a) (S(2)) and (1)L(b) (S(1)) of DMI was very prominent in the ordered LC environment (5CB) whereas in isotropic medium the dominant contribution for the formation of the lower energy band system primarily originates from the (1)Lb (S(1)) state, as evidenced from the steady-state polarization measurements. Both steady-state fluorescence quenching and time-resolved fluorescence studies clearly demonstrate in favor of the presence of only the static mode in LC environment. The situation differs in isotropic media where the dynamic process possesses the key role in the quenching mechanism. Expectedly, the transient absorption measurements by the nanosecond laser flash photolysis technique show a lack of formation of transient ionic species in the pseudo-ordered domain of 5CB. On the contrary, in isotropic solvents n-heptane and ACN, the transient absorption spectra measured by the same nanosecond laser flash photolysis technique exhibit the broad band of 9CNA radical anion at around 560 nm (9CNA-) and the band of neutral radical of DMI at 540 nm. It is inferred that the charge-separation reactions occurring within the present intermolecular systems could be stopped significantly by changing the nature of the environment from the isotropic to the LC's pseudo-ordered domain which situates closely above the nematic (N)-isotropic (I) phase transition temperature. From the steady-state and time-resolved investigations, it is revealed that, due to the hysteresis phenomenon, the nematic phase properties persist over a wide temperature range well within pseudo-ordered domain to some extent into the isotropic phases. The investigations with the different donor-acceptor inter- and intramolecular systems in 5CB and some other LC's environment are underway.

Percutaneous administration of progesterone: blood levels and endometrial protection.

There is controversy about the beneficial effects of topical progesterone creams used by postmenopausal women. A major concern is that serum progesterone levels achieved with progesterone creams are too low to have a secretory effect on the endometrium. However, antiproliferative effects on the endometrium have been demonstrated with progesterone creams when circulating levels of progesterone are low. Thus, effects of topical progesterone creams on the endometrium should not be based on serum progesterone levels, but on histologic examination of the endometrium. Despite the low serum progesterone levels achieved with the creams, salivary progesterone levels are very high, indicating that progesterone levels in serum do not necessarily reflect those in tissues. The mechanism by which the serum progesterone levels remain low is not known. However, one explanation is that after absorption through the skin, the lipophilic ingredients of creams, including progesterone, may have a preference for saturating the fatty layer below the dermis. Because there appears to be rapid uptake and release of steroids by red blood cells passing through capillaries, these cells may play an important role in transporting progesterone to salivary glands and other tissues. In contrast to progesterone creams, progesterone gels are water-soluble and appear to enter the microcirculation rapidly, thus giving rise to elevated serum progesterone levels with progesterone doses comparable to those used in creams.

Treatment of polymicrobial infections: post hoc analysis of three trials comparing ertapenem and piperacillin-tazobactam.

The efficacy of ertapenem 1 g once a day for the treatment of polymicrobial complicated intra-abdominal, complicated skin/skin-structure and acute pelvic infections was compared with piperacillin-tazobactam 3.375 g every 6 h in a post hoc analysis of data from three large randomized double-blind trials. Of the 1,558 treated patients in the three trials, no pathogen was identified in 345 (22.1%), 423 (27.2%) had a monomicrobial infection and 790 (50.7%) had a polymicrobial infection. At the test-of-cure assessment, there were no significant differences in outcome between the two treatment groups for any of the three infections. Cure rates (clinical and microbiological for intra-abdominal infection, clinical for skin/skin-structure and pelvic infections) in microbiologically evaluable patients for ertapenem and piperacillin-tazobactam, respectively, were 85.6% (154/180 evaluable patients) and 82.5% (127/154) for polymicrobial intra-abdominal infection, 80.3% (53/66) and 78.7% (48/61) for polymicrobial skin/skin-structure infection, and 95.7% (88/92) and 92.6% (88/95) for polymicrobial pelvic infection. Respective cure rates for all evaluable patients in the original trials were: 83.6% and 80.4% for intra-abdominal, 83.9% and 85.3% for skin/skin-structure, and 93.9% and 91.5% for pelvic infections. These data show that in the three trials, ertapenem 1 g once a day was highly effective for the treatment of polymicrobial infections and as effective as piperacillin-tazobactam 3.375 g every 6 h.

Ertapenem once a day versus piperacillin-tazobactam every 6 hours for treatment of acute pelvic infections: a prospective, multicenter, randomized, double-blind study.

OBJECTIVE: To compare ertapenem therapy with piperacillin-tazobactam therapy for the management of acute pelvic infections. METHODS: In a multicenter, double-blind study, 412 women with acute pelvic infection were assigned to one of two strata, namely obstetric/postpartum infection or gynecologic/postoperative infection, and were then randomized to ertapenem, 1 g once a day, or piperacillin-tazobactam, 3.375 g every 6 hours, both administered intravenously. RESULTS: In total, 163 patients in the ertapenem group and 153 patients in the piperacillin-tazobactam group were clinically evaluable. The median duration of therapy was 4.0 days in both treatment groups. The most common single pathogen was Escherichia coli. At the primary efficacy endpoint 2-4 weeks post therapy, 93.9% of patients who received ertapenem and 91.5% of those who received piperacillin-tazobactam were cured (95% confidence interval for the difference, adjusting for strata, -4% to 8.8%), indicating that cure rates for both treatment groups were equivalent. Cure rates for both treatment groups were also similar when compared by stratum and severity of infection. The frequency and severity of drug-related adverse events were generally similar in both groups. CONCLUSIONS: In this study, ertapenem was as effective as piperacillin-tazobactam for the treatment of acute pelvic infection, was generally well tolerated, and had an overall safety profile similar to that of piperacillin-tazobactam.

Does elevated body mass modify the influence of postmenopausal estrogen replacement on atherosclerosis progression: results from the estrogen in the prevention of atherosclerosis trial.

OBJECTIVE: To determine whether the estrogen-related reduction in atherosclerosis progression demonstrated in the estrogen in the prevention of atherosclerosis trial (EPAT) is modified by body mass index (BMI). STUDY DESIGN: Subgroup analyses were performed using data from EPAT, a randomized, double-blind, placebo-controlled trial designed to determine whether unopposed 17beta-estradiol administered for a 2-year treatment period reduces the progression of subclinical atherosclerosis in healthy postmenopausal women. The primary trial endpoint was the rate of change of common carotid artery intima-media thickness (IMT). In this subgroup analysis, the sample was divided into 122 women with BMI<30 kg/m(2) and 77 women with BMI> or =30 kg/m(2). Statistical analysis was performed using mixed general linear models to evaluate whether the treatment effects on IMT progression rates differed in the two BMI groups. RESULTS: There was no significant difference in the estradiol treatment effect on IMT progression rates between postmenopausal women with BMI<30 vs. > or =30 kg/m(2) (P=0.52). In the 77 subjects who did not use lipid-lowering therapy, there was significant improvement in IMT with estradiol treatment that was evident in both BMI groups (P=0.48 for differences between BMI groups). CONCLUSIONS: In contrast to the epidemiological observation that obese postmenopausal women do not derive benefit from estrogen replacement therapy, results of this study indicate that estradiol treatment is beneficial in preventing progression of atherosclerosis regardless of initial BMI. CONDENSATION: Estradiol treatment is beneficial in preventing progression of atherosclerosis in postmenopausal women not receiving lipid-lowering therapy, regardless of their initial body mass index.

Improving appropriate use of antifungal medications: the role of an over-the-counter vaginal pH self-test device.

OBJECTIVES: To determine whether patients can understand and use the vaginal pH device in the diagnosis of vaginitis. To compare whether vaginal pH readings determined by patients and healthcare providers are similar. To determine whether vaginal pH can reduce inappropriate over-the-counter (OTC) antifungal medication use and improve the correct diagnosis of vaginitis. METHODS: One hundred and fifty-one women indicated their belief about the cause of their vaginal infection, read the instructions of the vaginal pH device package insert, used the device and interpreted the findings. The patient interpretations were compared with results obtained by healthcare providers, blinded to patient findings. RESULTS: Over 96% of patients stated that they could easily read the instructions, use the vaginal pH device and interpret the readings. They obtained the same readings as healthcare professionals (Kappa = 0.9). Restricting the use of OTC antifungal medications to those individuals with vaginitis symptoms and vaginal pH < or = 4.5 significantly reduced inappropriate use by approximately 50%, Fisher's exact test, p-value = 0.018. Conversely, seeking healthcare provider assessment with vaginal pH > 4.5, leads to correct diagnosis of vaginitis. CONCLUSIONS: The vaginal pH device can be used as an OTC diagnostic tool by consumers when a vaginal infection is suspected. Vaginal pH readings would direct patients whether to purchase an antifungal medication or seek professional diagnosis from a healthcare provider. Understanding and use of this vaginal pH device could reduce inappropriate use of OTC antifungal medications by approximately 50% and improve the correct diagnosis of vaginitis.