Electrical Properties and AC Conductivity of (Bi0.5Na0.5)0.94Ba0.06TiO3 Ceramic

Lead-free perovskite (Bi0.5Na0.5)0.94Ba0.06TiO3 (BNBT06) was prepared by conventional ceramic fabrication technique at 1160°C/3h in air atmosphere. The crystal structure, microstructure, dielectric, polarization, piezoelectric properties, and ac conductivity of the sample were studied. X-ray diffraction data confirmed the formation of a single phase tetragonal unit cell. Williamson-Hall plot was used to calculate the lattice strain and the apparent particle size. The experimental relative density of BNBT06 was found to be ~96-97% of the theoretical one with an average grain size ~4 μm. Room temperature dielectric constant and loss factor at 1 kHz were found to be equal to 781 and 0.085, respectively. Longitudinal piezoelectric charge coefficient of the poled sample under 2.5 kV/mm at 80°C in silicone bath was found to be equal to 124 pC/N. Complex impedance and electric modulus spectroscopic analyses showed the dielectric relaxation in the material to be of non-Debye type. The Nyquist plots and conductivity studies showed the NTCR character of BNBT06. The correlated barrier hopping model (CBHM) as well as jump relaxation model (JRM) was found to successfully explain the mechanism of charge transport in BNBT06. The ac conductivity data were used to evaluate the minimum hopping length, apparent activation energy, and density of states at Fermi level.

Histomorphometric and sympathetic innervation of the human posterior intercostal artery and its clinical importance

The purpose of this investigation was to study the characteristics of arterial wall and sympathetic innervation of the human posterior intercostal artery (PIA) in order to assess its suitability as an arterial graft for vascular surgeries. Fifty PIA samples were obtained from 25 cadavers (18 males and 7 females). Samples were divided into three age groups: group 1: 19-40 years; group 2: 41-60 years; and group 3 over 61 years. Sections (5 μm-thickness) of each sample were taken and stained with haematoxylin-eosin, Verhoeff's-Van Gieson. Five samples were processed for tyrosine hydroxylase immunostaining. The differences in the thickness of tunica intima were not statistically significant when group 1 was compared with group 2 (p = 0.798), but significant differences were observed in the thickness of the tunica intima when comparing group 2 with group 3 (p = 0.012) and group 3 with group 1 (p = 0.002). The tunica media was not statistically significant when group 1 was compared with group 2 (p = 0.479). However, significant differences were observed in the thickness of the tunica media when comparing group 2 with group 3 (p = 0.001) and group 3 with group 1 (p = 0.011). The mean (SD) number of elastic laminae in group 1, group 2, and group 3 were 7.88 ± 0.69, 6.62 ± 0.51, and 4.56 ± 0.82, respectively. Tunica intima/media ratios in groups 1, 2, and 3 were found to be 0.09 ± 0.01, 0.11 ± 0.02, and 0.27 ± 0.16, respectively. Tyrosine hydroxylase immunostaining revealed that sympathetic fibres are found mainly in the tunica adventitia and at the adventitia-medial border. The sympathetic nerve fibre area and sympathetic index were found to be 0.004 mm2, and 0.151 mm(2), respectively. PIA has relatively thin intima and media, which are favourable features regarding its potential suitability as an alternate coronary bypass conduit.

Normobaric oxygen therapy in acute ischemic stroke: A pilot study in Indian patients

Purpose:

Clinical and radiological assessment of effects of normobaric high-flow oxygen therapy in patients with acute ischemic stroke (AIS).

Materials and Methods:

Patients with anterior circulation ischemic strokes presenting within 12 h of onset, ineligible for intravenous thrombolysis, an National Institute of Health Stroke Scale (NIHSS) score of >4, a mean transit time (MTT) lesion larger than diffusion-weighted image (DWI) (perfusiondiffusion mismatch), and an evidence of cortical hypoperfusion on magnetic resonance imaging (MRI) were included into the trial. Active chronic obstructive pulmonary disease (COPD), requirement of >3/L min oxygen delivery to maintain SaO2 > 95%, rapidly improving neurological deficits, pregnancy, contraindications to MRI, or unstable medical conditions were excluded. The experimental group received humidified oxygen at flow rates of 10 L/min for 12 h. The NIHSS, modified Rankin Score (mRS), Barthel Index (BI) were measured at 0, 1, 7 day of admission and at 3 months follow-up. MRI with DWI/PWI was performed at admission, 24 h later and at 3 months follow-up.

Results:

Of 40 patients (mean age = 55.8 years ± 13.2) (range, 26–82), 20 patients were randomized to normobaric oxygen (NBO). The mean NIHSS in NBO and control groups were 14.25 and 12.7 at admission which decreased to 11.6 and 9.5 on the seventh day, and 9.4 and 9.05 at 3 months, respectively. The mean mRS (3.7/3.7) and BI (58.2/53.9) in NBO and control groups improved to 2/2.2 and 73.05/73.8 at the end of 3 months, respectively.

Conclusions:

NBO did not improve the clinical scores of stroke outcome in Indian patients with AIS.

Evaluation of coloring efficacy of lac dye in comminuted meat product

Effect of incorporation of graded levels (4, 6, 8, 10, 25 ppm) of lac dye on coloring efficacy and possible use of this natural color in processed meat products was studied. Inclusion of lac dye at different concentrations did not affect the pH significantly whereas a linear increase in the Lovibond red color unit of chicken nuggets was noted with raising the level of lac dye from 4 to 10 ppm. The sensory rating for color was highest at addition level of 25 ppm of lac dye and it was comparable to color score of the product containing 200 ppm sodium nitrite. Lac dye inclusion in nuggets at all concentrations studied had better antimicrobial properties as compared to 200 ppm sodium nitrite. It was concluded that lac dye from 10 to 25 ppm could be incorporated in comminuted meat products as a natural colorant with antimicrobial action.

Chlamydia pneumoniae seropositivity in adults with acute ischemic stroke: A case-control study

BACKGROUND

Causative role of Chlamydia pneumoniae infection in patients with acute ischemic stroke (AIS) remains unresolved till date.

AIM

To investigate the role of C. pneumoniae antibodies in AIS.

MATERIALS AND METHODS

Patients with AIS and sex- and environment-matched controls were enrolled. Antibodies to C. pneumoniae (IgA, IgG and IgM) were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

A total of 51 patients and 48 controls were enrolled. The IgA seropositivity was significantly associated with AIS (unadjusted odds ratio 3.1; 95% CI 1.38, 6.96; P = 0.005), whereas IgG (unadjusted OR 0.44; 95% CI 0.18, 1.09; P = 0.07) and IgM (unadjusted OR 1.1; 95% CI 0.36, 3.3; P = 0.88) were not. There was no difference in IgA or IgG positivity in different stroke subtypes. On multivariate analysis after adjusting for sex, hypertension, diabetes mellitus, smoking and alcohol, the IgA seropositivity yielded an adjusted OR for stroke (4.72; 95% CI 1.61, 13.83; P = 0.005), while IgG seropositivity did not (OR 0.25; 95% CI 0.08, 0.83; P = 0.23).

CONCLUSIONS

An increased risk of AIS was demonstrated in patients seropositive for C. pneumoniae for IgA antibodies.

Influence of Doping on the Structural Properties of Micro-Crystalline Silicon Prepared with the VHF-GD Technique at Low Deposition Temperatures

In doped and undoped microcrystalline silicon prepared with Very High Frequency Glow Discharge, hydrogen is found to be mainly located at the grain boundaries from where it desorbs easily at low annealing temperatures. In undoped material hydrogen evolution peaks are between 400°C and 500°C. Upon doping, a new major peak appears at 300°C and a strong reduction of the typical Si-H infrared absorption bands are found for doped samples when annealed up to 300°C. This is accompanied by an increase of the conductivity due to either de-passivation of dopants in the crystallites or a favourable reconstruction at the grain boundaries. Hydrogen profiles show a hydrogen depletion at the film/air interface that is more profound in doped material, thus correlating with the appearance of the low temperature evolution peak. The high free carrier density in the crystallites of the doped material gives rise to strong optical absorption. Although correlating nicely with conductivity, the free carrier absorption cannot be evaluated simply in terms of die Drude theory. In view of the high conductivities and the dominance of Si-H surface bonds we argue that our material does not contain a large amount of amorphous tissue.

TiO2:Ce/CeO2 High Performance Insulators For Thin Film Electroluminescent Devices

The electrical properties of titanium dioxide thin films have been stabilised by cerium doping. These films have a high permittivity between 35 to 45 and withstand 650°C. Multilayer TiO2:Ce/CeO2 insulators have been fabricated. The breakdown voltage is increased by a factor 10 with a modest decrease in the permittivity (30 – 35 instead of 35 – 45).

Electroluminescent devices (ELDs) with a classical ZnS:Mn phosphor have been prepared using TiO2:Ce as the first insulator and a TiO2:Ce/CeO2 multilayer as the second insulator. Compared with a standard ELD based on Y2O3 insulators, devices with the new insulators show a significant decrease of the threshold voltage along with a notable increase of the brightness. An important increase is also achieved in the total device efficiency which is maintained over a large range of brightness and transferred charge. Consequences of rapid thermal annealing and conventional thermal treatments on device performance have also been investigated.

Abnormalities of the corpus callosum in non-psychotic high-risk offspring of schizophrenia patients

Alterations in the structure of the corpus callosum (CC) have been observed in schizophrenia. Offspring of schizophrenia parents have 10-15 times higher risk for developing schizophrenia. We examined CC volume in offspring at genetic high-risk (HR) subjects. Since the sub-regions of the CC are topographically mapped to cortical brain regions, we hypothesized that HR subjects may show a decrement in total volume and differential volume decreases in sub-regions of the CC. The offspring of schizophrenia parents (HR; n=70; 36 males) and healthy volunteers with no family or personal history of psychotic disorders (healthy controls (HC); n=73; 37 males) matched for age, gender and education were selected for the study. Magnetic resonance images were collected using a GE 1.5 T scanner and processed using FreeSurfer image analysis software. The CC was divided into five neuroanatomically based partitions. The volume of total CC and the five sub-regions were measured blind to clinical information. With covariation for intracranial volume, HR subjects had significantly reduced total CC, more prominently observed in the anterior splenium. An age-related increase in CC volume was found in the anterior and posterior splenium of healthy controls but not in HR subjects. The volume reduction was greater in male than female HR subjects. The volume reduction in the CC may reflect a reduction in axonal fibers crossing the hemispheres and/or myelination between the left and right temporo-parietal cortices. The absence of an age-related volume increase suggests an abnormal developmental trajectory that may underlie susceptibility to schizophrenia.

Epilepsy surgery in a pediatric population: a retrospective study of 129 children from a tertiary care hospital in a developing country along with assessment of quality of life

PURPOSE

To assess the outcome of a pediatric population operated for drug-resistant epilepsy from a large tertiary care center in India.

METHODS

Retrospectively: quality of life (QOL); prospectively: preoperative assessment included interictal EEG, MRI (as per epilepsy protocol), video-EEG. Ictal SPECT (with subtraction) and PET were performed when required. QOL scores were assessed using the HASS or SSQ for seizure severity, Quality of Life in Childhood Epilepsy (QOLCE) for QOL, and Child Behavior Check List (CBCL) for behavior.

RESULTS

142 were operated from January 2000 to June 2011 by the senior author. 118 patients with at least 1 year of follow-up were included in the study. Mean age at surgery was 9.8 ± 4.3 years. In addition, 40 patients underwent QOL assessment prospectively both before and after surgery. Mean duration of epilepsy was 5.3 ± 3.3 years. A class I outcome (Engel's) was seen in 79.5% patients, class II in 8.6%, class III in 10.7%, and class IV in 1 patient. As per surgical procedures, class I outcome in patients who underwent temporal resection, hemispherotomy and extratemporal resection was 76, 87 and 72%, respectively. QOL scores correlated with duration of seizures, epileptic encephalopathy and outcome of surgery, but not with side of surgery, age and sex.

CONCLUSIONS

This study, the largest reported from India, has demonstrated satisfactory results for epilepsy surgery in children.