Study on damage of Gd2O3-CeO2 under electronic energy loss: comparison between bulk-like and nanostructure.

To understand the physical phenomena responsible for radiation damage of the materials used in nuclear reactors, and thus study their operation life and/or efficiency, it is required to simulate the conditions by exposing the materials to energetic ions. Ceria (CeO2) has been proposed as one of the inert matrices for the transmutation of minor actinides in the futuristic inert matrix fuel (IMF) concept. The inert matrix should also contain burnable poison to compensate for the initial reactivity of fuel. In this context, gadolinium (Gd) is an excellent burnable poison with a high neutron absorption cross-section. In view of this, Gd2O3-CeO2 nano-powders were synthesized and sintered at 800 °C and 1300 °C to obtain different grain sizes and morphologies. FESEM and TEM were carried out to study the grain size of pristine pellets. The sintered pellets were irradiated with 80-MeV Ag ions (electronic energy loss (Se) regime) at room temperature to emulate the effect of fission fragments. For analysis of the effect of grain size on the irradiation-induced structural degradation at different fluences, GIXRD and Raman spectroscopy were performed. Significantly large damage has been observed for the smaller grain-sized samples (sintered at 800 °C) as compared to the large grain-sized sample (sintered at 1300 °C). Neither of the samples amorphized under the present experimental conditions as indicated by the presence of the Raman-active T2g mode (centred at 462 cm-1) and all the XRD peaks of fluorite cubic structure up to the highest fluence employed (1 × 1014 ions cm-2). X-ray photoelectron spectroscopy results demonstrate that Ce4+ to Ce3+ and vacancy-related isolated clusters are the main defects produced in the systems. The radiation tolerance behaviour of the samples is understood with the help of thermal spike simulation, which indicates higher transient lattice temperatures with longer duration in the smaller grain-sized sample upon irradiation. Gd-doped ceria thus possesses good radiation stability in the Se regime, indicating its potential for application in IMFs.

Radiation response of Y3Al5O12 and Nd3+-Y3Al5O12 to Swift heavy ions: insight into structural damage and defect dynamics.

Understanding the behavior of a material under irradiation is paramount to its application in the nuclear industry. The present work explores the radiation response of garnet Y3Al5O12 (YAG) and Nd3+-substituted Y3Al5O12 (Nd-YAG) under a 100 MeV Iodine beam at varying fluences to mimic the effect of fission fragments. This is relevant to the potential application of garnet as a host for minor actinide (MA) transmutation (Nd3+: surrogate for long-lived MA (Am3+, Np3+, Cm3+)). The un-irradiated and irradiated YAG and Nd-YAG samples were investigated by X-ray diffraction and Raman spectroscopy. Positron annihilation spectroscopy, thermal spike modelling and theoretical studies have been employed to understand the role of substitution and defect energetics in influencing this radiation response. Although both materials were not completely amorphized under the present irradiation conditions, a tremendous loss in crystallinity could be observed with increase in fluence, the damage being much more in Nd-YAG. Ion track radii of 2.17 nm and 2.91 nm were estimated for YAG and Nd-YAG respectively. Thermal-spike calculations show an increase in radiation-induced transient temperatures upon Nd-substitution that causes greater radiation damage in Nd-YAG. The enhancement in radiation-induced damage with increasing ion-fluence manifests in broadening and weakening of the Raman modes and XRD peaks. An increase in the average positron annihilation lifetime indicated the creation of oxygen vacancies. The defect formation energies of Y3Al5O12 have been theoretically estimated via density functional theory (DFT) and unfavorable energies required for creating cation pair anti-sites have been proposed as one of the possible reasons for the relatively poorer radiation response of YAG. The irradiation behavior of Y3Al5O12 has been compared with disordered fluorite (YSZ) and zirconate pyrochlores, which are well-researched ceramics for MA transmutation.

Validation of age and height based formulae to predict paediatric airway distances - a prospective observational study.

Background: Preoperative airway evaluation in children is an important part of routine preanesthetic evaluation before surgery. External airway measurements, viz., thyromental, mentohyoid, and sternomental distances, while being growth dependent, could identify pediatric patients with potentially difficult airways. Objectives: This study was conducted to validate the age- and height-based formulae, derived from a previous study conducted in our institute, to predict thyromental distance, sternomental distance, and mentohyoid distance in relation with the height and age of pediatric patients. Design: Prospective cross-sectional single arm observational study. Setting: Tertiary level university teaching hospital from July 2015 to December 2016. Patients: Children (202) in the age group of 3-15 years with no obvious external airway anomaly scheduled for elective surgery under general anesthesia. Outcomes Measured: The thyromental, mentohyoid, and sternomental distances were measured preoperatively. The same parameters were then calculated based on age- and height-related formulae derived in the earlier study. Results: Bland-Altman analysis of the sample patients showed a mean difference (bias) between measured and calculated values ranging from 0.14 to -0.60 (3 - 13%). Overall agreement in terms of bias were found to be more with height-based equation for mentohyoid distance and thyromental distance and age-based equation for sternomental distance. Conclusion: Our study validates the formulae derived in the earlier study to predict thyromental, mentohyoid, and sternomental distances in children with no obvious external airway anomalies. Further studies are needed to extend the applicability of these formulae in obese children and those with craniofacial anomalies coming for general anesthesia and surgery.

The evolution of robotic surgery: surgical and anaesthetic aspects.

Robotic surgery pushes the frontiers of innovation in healthcare technology towards improved clinical outcomes. We discuss the evolution to five generations of robotic surgical platforms including stereotactic, endoscopic, bioinspired, microbots on the millimetre scale, and the future development of autonomous systems. We examine the challenges, obstacles and limitations of robotic surgery and its future potential including integrated real-time anatomical and immune-histological imaging and data assimilation with improved visualisation, haptic feedback and robot-surgeon interactivity. We consider current evidence, cost-effectiveness and the learning curve in relation to the surgical and anaesthetic journey, and what is required to continue to realise improvements in surgical operative care. The innovative impact of this technology holds the potential to achieve transformative clinical improvements. However, despite over 30 yr of incremental advances it remains formative in its innovative disruption.

Early primary biliary cholangitis is characterised by brain abnormalities on cerebral magnetic resonance imaging.

BACKGROUND: Brain change can occur in primary biliary cholangitis (PBC), potentially as a result of cholestatic and/or inflammatory processes. This change is linked to systemic symptoms of fatigue and cognitive impairment. AIM: To identify whether brain change occurs early in PBC. If the change develops early and is progressive, it may explain the difficulty in treating these symptoms. METHODS: Early disease brain change was explored in 13 patients with newly diagnosed biopsy-proven precirrhotic PBC using magnetisation transfer, diffusion-weighted imaging and 1 H magnetic resonance spectroscopy. Results were compared to 17 healthy volunteers. RESULTS: Cerebral magnetisation transfer ratios were reduced in early PBC, compared to healthy volunteers, in the thalamus, putamen and head of caudate with no greater reduction in patients with greater symptom severity. Mean apparent diffusion coefficients were increased in the thalamus only. No 1 H magnetic resonance spectroscopy abnormalities were seen. Serum manganese levels were elevated in all PBC patients, but no relationship was seen with imaging or symptom parameters. There were no correlations between neuroimaging data, laboratory data, symptom severity scores or age. CONCLUSIONS: This is the first study to be performed in this precirrhotic patient population, and we have highlighted that neuroimaging changes are present at a much earlier stage than previously demonstrated. The neuroimaging abnormalities suggest that the brain changes seen in PBC occur early in the pathological process, even before significant liver damage has occurred. If such changes are linked to symptom pathogenesis, this could have important implications for the timing of second-line-therapy use.

A three-point time series study of antibiotic usage on an intensive care unit, following an antibiotic stewardship programme, after an outbreak of multi-resistant Acinetobacter baumannii.

Antibiotic use in intensive care units (ICUs) can promote antimicrobial resistance. Outbreaks of multi-resistant bacteria significantly affect patient outcomes and delivery of care. Antibiotic stewardship programmes (ASPs), combining root-cause analyses and multi-faceted prevention strategies, are necessary, often at significant cost and time. Which elements of such strategies have the largest impact on antibiotic usage following an outbreak is unclear. The aim of this study was to investigate how antibiotic usage in a university hospital ICU changed with a non-protocolised ASP following a disruptive outbreak of multi-resistant Acinetobacter baumannii (MRAB). This was a three time-period observational cohort study. The primary endpoint was the change in overall antibiotic usage (daily defined dose, DDD, antibiotic-days, antibiotic-courses) for consecutive ICU patients staying >48 h, over three 6-month study time periods pre-MRAB (2008, n = 84) and post-MRAB (2010, n = 88; 2012, n = 122). Secondary endpoints were changes in antibiotic usage and patient demographics, in predefined admission categories (Medical Emergency, ME; Surgical Elective, SEL; and Surgical Emergency, SE). The mean age (54.6 ± 17.7, 58.1 ± 17.9, 62.8 ± 19.1 years*) and severity of illness (APACHE 14.8 ± 8.0, 16.7 ± 6.8, 18.3 ± 6.1*) increased, particularly medical admissions. There was a sustained reduction in DDD antibiotic usage [1895.1 (2008), 1224.2 (2010), 1236.6 (2012) per 1000 patient-days] but no overall change in antibiotic-days or antibiotic-courses. Antibiotic usage (antibiotic-days) fell significantly in surgical emergency admissions [20.2 ± 32.1, 4.6 ± 7.4*, 5.9 ± 7.3]. There was a sustained drop in beta-lactam, quinolone, glycopeptide and macrolide usage. Following an MRAB outbreak, and subsequent operational changes including enhanced ASPs (non-protocolised), there was a sustained overall fall in antibiotic usage in spite of an increase in disease severity over 5 years.

The role of reaction conditions in the polymorphic control of Eu3+ doped YInO3: structure and size sensitive luminescence.

With the aim of exploring the effect of particle size and different polymorphic structures on the luminescence behaviour of Eu(3+) ions, all in a single compound, the YInO(3):Eu(3+) system was synthesized. Metastable C-type modification could be obtained in YInO(3) nanopowders synthesized by gel combustion. The broadening in Raman modes has been related to both the particle size and the strain in the metastable C-type modification. The hexagonal polymorph of YInO(3), with a layered structure, quite unlike the C-type modification, could be obtained by heating nanopowders to 1175 °C. Such a change in the structure, leading to different site symmetries for Eu(3+) ions exhibited a tremendous bearing on its luminescence behaviour. Detailed steady state and time resolved luminescence studies revealed a highly distorted local site symmetry for the Y(3+) ion in hexagonal YInO(3). The nano C-type YInO(3) exhibited greater asymmetry and a shorter lifetime as compared to the bulk C-type YInO(3), attributable to more surface defects in the case of the former. The Judd-Ofelt parameters (Ω(2) and Ω(4)) were determined which established a much higher asymmetry in the hexagonal modification. Along with higher lifetime, the hexagonal polymorph also possessed superior quantum yield values. In addition to providing a significant insight into the structure-luminescence correlation in this study, we propose an efficient red phosphor with a high red color purity.

Effect of grain size and microstructure on radiation stability of CeO2: an extensive study.

To investigate the variation in the radiation stability of ceria with microstructure under the electronic excitation regime, ceria samples sintered under different conditions were irradiated with high energy 100 MeV Ag ions. The ceria nanopowders were synthesized and sintered at 800 °C (S800), 1000 °C (S1000) and 1300 °C (S1300), respectively. The samples with widely varying grain size, densities and microstructure were obtained. The pristine and irradiated samples were studied by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). None of the samples amorphized up to the highest fluence of 1 × 10(14) ions per cm(2) employed in this study. XRD and Raman studies showed that the sample with lowest grain size suffered maximum damage while the sample with largest grain size was most stable and showed little change in crystallinity. Raman spectroscopy indicated the enhanced formation of Ce(3+) and related defects in the sample with larger grain size after irradiation. The most intriguing result was the absence of Ce(3+)-related defects in the sample with lowest grain size which actually showed maximum damage upon irradiation. The XPS studies on S800 and S1300 provided concrete evidence for the presence of Ce(3+) and oxygen ion vacancies in S1300. The grain boundaries and grain size dependent stability have been discussed.

Chest ultrasonography in emergency Cesarean delivery in multi-valvular heart disease with pulmonary edema during spinal anesthesia.

Valvular heart disease in a parturient presenting for Cesarean section is challenging. A 25 year old primigravida parturient with severe mitral stenosis, mild mitral regurgitation, mild aortic regurgitation, and mild pulmonary arterial hypertension required Cesarean delivery after developing pulmonary edema. Low-dose spinal with hyperbaric bupivacine 0.5% 1.8 mL plus 25 µg of fentanyl was used for anesthesia. Chest ultrasonography (US) and transthoracic echocardiography (TTE) were used for monitoring purposes. Spinal-induced preload reduction improved the pulmonary edema, as evidenced by chest US. Chest US and TTE helped in fluid management.

CSF p-Tau levels in the prediction of Alzheimer's disease.

The two hallmarks of Alzheimer's disease (AD) are neurofibrillary tangles and amyloid plaques. Neurofibrillary tangles are formed due to the hyperphosphorylation of tau protein. There is an urgent need to develop a reliable biomarker for the diagnosis of AD. Cerebrospinal fluid (CSF) is surrounding the brain and reflects the major neuropathological features in the AD brain. Diagnosis, disease progression and drug actions rely on the AD biomarkers. Mainly CSF tau and phosphorylated tau (p-Tau) have been observed to serve the purpose for early AD. Keeping in view the early appearance of p-Tau in CSF, we analyzed p-Tau levels in 23 AD, 23 Non AD type dementia (NAD), 23 Neurological control (NC) and 23 Healthy control (HC) North Indian patients. The levels of p-Tau were found to be increased in AD patients (67.87±18.05 pg/ml, SEM 3.76) compared with NAD (47.55±7.85 pg/ml, SEM 1.64), NC (34.42±4.51 pg/ml, SEM 0.94) and HC (27.09±7.18 pg/ml, SEM 1.50). The resulting sensitivity for AD with NAD was 80.27% whereas with respect to the NAD, NC and HC was 85.40%. Therefore elevated levels of p-Tau in AD can be exploited as a predictive biomarker in North Indian AD patients.

Experimental and theoretical investigations on the polymorphism and metastability of BiPO4.

In this work we report the metastability and the energetics of the phase transitions of three different polymorphs of BiPO4, namely trigonal (Phase-I, space group P3(1)21), monoclinic monazite-type (Phase-II, space group P2(1)/n) and SbPO4-type monoclinic (Phase-III, space group P2(1)/m) from ambient and non-ambient temperature powder XRD and neutron diffraction studies as well as ab initio density functional theory (DFT) calculations. The symmetry ambiguity between P2(1) and P2(1)/m of the high temperature polymorph of BiPO4 has been resolved by a neutron diffraction study. The structure and vibrational properties of these polymorphs of the three polymorphs have also been reported in detail. Total energy calculations have been used to understand the experimentally observed metastable behavior of trigonal and monazite-type BiPO4. Interestingly, all of the three phases were found to coexist after heating a single phasic trigonal BiPO4 to 773 K. The irreversible nature of these phase transitions has been explained by the concepts of the interplay of the structural distortion, molar volume and total energy.

Cerebral microglial activation in patients with hepatitis C: in vivo evidence of neuroinflammation.

Patients with chronic hepatitis C infection may exhibit neuropsychological symptoms and cognitive impairment. Post-mortem studies of hepatitis C virus HCV quasispecies and replicative intermediates indicate that the brain might act as a separate compartment for viral replication and microglia may be the locus for infection and subsequent neuroinflammatory activity. We sought to use two independent in vivo imaging techniques to determine evidence of neuroinflammation in patients with histologically mild chronic hepatitis C. Using positron emission tomography (PET) with a ligand for microglial/brain macrophage activation, (11)C-(R)-PK11195 (PK11195) and cerebral proton magnetic resonance spectroscopy, we determined whether there was evidence of neuroinflammation in a pilot study of 11 patients with biopsy-proven mild chronic hepatitis C, compared to healthy volunteers. Patients were characterized by cognitive testing and the fatigue impact scale to assess for CNS impairment. PK11195 binding potential was significantly increased in the caudate nucleus of patients, compared to normal controls (P = 0.03). The caudate and thalamic binding potential were more significantly increased in six patients with genotype 1 infection (P = 0.007) and positively correlated with viraemia (r = 0.77, P = 0.005). Basal ganglia myo-inositol/creatine and choline/creatine ratios were also significantly elevated in patients with chronic hepatitis C compared to normal controls (P = 0.0004 and P = 0.01, respectively). Using PET, we demonstrated evidence of microglial activation, which positively correlated with HCV viraemia and altered cerebral metabolism in the brains of patients with mild hepatitis C. This provides further in vivo evidence for a neurotropic role for HCV.

Multicolored and white-light phosphors based on doped GdF3 nanoparticles and their potential bio-applications.

Rare-earth-doped gadolinium fluoride nanocrystals were synthesized by a single step synthesis employing ethylene glycol as solvent. Based on X-ray diffraction studies, stabilization of hexagonal modification of GdF(3) has been inferred. The microscopic studies show formation of uniformly distributed nanocrystals (~15 nm). The nanoparticles are readily dispersible in water and show bright luminescence in colloidal solution. The luminescence properties have been investigated as a function of activator concentrations, and enhanced optical properties have been attributed to efficient energy transfer from the Gd(3+) to the activator RE(3+) ions, which has further been confirmed by steady-state and time-resolved optical studies. It has been demonstrated that on doping appropriate amount of activators in host GdF(3), a novel white-light-emitting phosphor is obtained with CIE co-ordinates and correlated color temperature (CCT) very close to broad daylight. This can have promising applications as phosphor for white-light ultraviolet-light-emitting diodes (UV-LEDs). Our experiments showed efficient labeling of human breast carcinoma cells (MCF-7) by Tb(3+)-doped GdF(3) nanoparticles. The fluorescence intensity was found to be dependent on the surface modifying/coating agent, and the results were validated using confocal microscopy in terms of localization of these functionalized nanoparticles.

Sm(2-x)Dy(x)Zr2O7 pyrochlores: probing order-disorder dynamics and multifunctionality.

The present work involves the synthesis of a series of Sm(2-x)Dy(x)Zr(2)O(7) compounds (0.0 ≤ x ≤ 2.0) by a controlled gel combustion process. The powders were thoroughly analyzed by powder X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy, and diffuse-reflectance UV-visible spectroscopy. The powder XRD studies revealed the system to be single-phasic throughout with retention of pyrochlore-type ordering until 40 mol % of Dy(3+), beyond which the pyrochlore lattice gives way to the defect fluorite structure. Interestingly, Raman spectroscopic studies (as against XRD studies) showed retention of pyrochlore-type ordering throughout the homogeneity range of the compositions studied. This is perhaps the first study that reports retention of a weak pyrochlore-type superstructure in the Dy(2)Zr(2)O(7) system, which was otherwise known to crystallize in the defect fluorite system. The ionic conductivity measurements showed an increase in the activation energy (E(a)) with an increase in the mole percent of Dy(3+) owing to the decreased mobility with an increase in the degree of disorder. The system possesses a tunable band gap with varying amounts of Dy(3+). First-principles calculations were performed to support a decrease in the band gap of the doped system with an increase in the Dy(3+) content. The potential as photocatalysts of some of these compositions was explored, and they exhibited high photocatalytic activity for degradation of xylenol orange, with t(1/2) increasing from pure Sm(2)Zr(2)O(7) to pure Dy(2)Zr(2)O(7).

Apo-Eε4 allele in conjunction with Aß42 and tau in CSF: biomarker for Alzheimer's disease.

The objective of this study was to elucidate an association between Apo- Eε4 allele and CSF biomarkers Aß42 and tau for the diagnosis of Alzheimer's Disease (AD) patients. Aß42 and tau protein concentrations in CSF were measured by using ELISA assays. The levels of Aß42 were found to be decreased where as tau levels increased in AD patients. Moreover in AD patients Apo-Eε4 allele carriers have shown low Aß42 levels (328.86 ± 99.0 pg/ml) compared to Apo-Eε4 allele non-carriers (367.52 ± 5 7.37 pg/ml), while tau levels were higher in Apo-Eε4 allele carriers (511 ± 44.67 pg/ml) compared to Apo-Eε4 allele non-carriers (503.75 ± 41.08 pg/ml). Combination of Aß42 and tau resulted in sensitivity of 75.38% and specificity of 94.82% and diagnostic accuracy of 84.30% for AD compared with the controls. Therefore low Aß42 and elevated tau concentrations in CSF may prove to be a better diagnostic marker for AD along with the Apo-Eε4 allele.

Solid state white light emitting systems based on CeF3: RE3+ nanoparticles and their composites with polymers.

A series of doped CeF(3): RE(3+) (RE(3+): Tb(3+), Eu(3+) and Dy(3+)) nanoparticles were synthesized, with the aim of obtaining a white light emitting composition, by a simple polyol route at 160°C and characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FT-IR) and photoluminescence. Uniformly distributed and highly water-dispersible rectangular nanoparticles (length ~15-20 nm, breadth ~5-10 nm) were obtained. The steady state and time resolved luminescence studies confirmed efficient energy transfer from the host to activator ions. Lifetime studies revealed that optimum luminescence is observed for 2.5 mol% Dy(3+) and 7.5 mol% Tb(3+). The energy transfer efficiencies (Ce(3+) to activators) were found to be 89% for CeF(3): Tb(3+) (7.5 mol%) nanoparticles and 60% for CeF(3): Dy(3+) (2.5 mol%) nanoparticles. Different concentrations of Tb(3+), Eu(3+) and Dy(3+) were doped to achieve a white light emitting phosphor for UV-based LEDs (light emitting diodes). Finally CeF(3), triply doped with 2.0 mol%Tb(3+), 4.5 mol% Eu(3+) and 3.5 mol% Dy(3+), was found to have impressive chromaticity co-ordinates, close to broad day light. The colloidal solutions of doped CeF(3) nanoparticles emitted bright green (Tb(3+)), blue (Dy(3+)) and white (triply doped) luminescence upon host excitation. Composites of poly methyl methacrylate (PMMA) and poly vinyl alcohol (PVA) were made with CeF(3): 5.0 mol%Tb(3+), CeF(3): 5.0 mol% Dy(3+) and triply doped white light emitting composition. The CeF(3)/PMMA (PVA) nanocomposite films, so obtained, are highly transparent (in the visible spectral range) and exhibit strong photoluminescence upon UV excitation.

Cerebrospinal fluid profile of amyloid ß42 (Aß42), hTau and ubiquitin in North Indian Alzheimer's disease patients.

Alzheimer's disease (AD) is the most common form of dementia, and is characterized by the degeneration of neurons and their synapses, and a higher number of amyloid plaques and neurofibrillary tangles (NFTs) compared with that found in non-demented individuals. Amyloid-ß-peptides (Aß) are major components of amyloid plaques in AD brain whereas NFTs are composed of Tau and associated with ubiquitin. The aim of the present study was to analyze the levels of Aß42, hTau (total Tau) and ubiquitin in CSF of North Indian population. CSF Aß42, Tau and ubiquitin were measured in CSF of AD patients as well as controls using ELISA assays. Here we report low Aß42 levels in AD patients (324.24±76.38pg/ml) as compared to those in non-AD (NAD) (668.34±43.13pg/ml), neurological controls (NCs) (727.28±46.49pg/ml) and healthy controls (HCs) (976.47±124.46pg/ml). In contrast, hTau and ubiquitin levels were significantly high (568.65±48.89pg/ml and 36.82±4.34ng/ml, respectively) in AD patients compared to those in NAD, NC and HC. The hTau levels were 267.37±36.64pg/ml, 167.34±44.27pg/ml and 107.62±24.27pg/ml in NAD, NC and HC, respectively. Similarly, ubiquitin levels were 23.57±2.32ng/ml, 19.76±3.64ng/ml and 13.24±4.56ng/ml in NAD, NC and HC, respectively. In conclusion, low Aß42 and high Tau-ubiquitin levels were found in North Indian AD patients.