A novel fuel cell design foroperandoenergy-dispersive x-ray absorption measurements

A polymer electrolyte fuel cell has been designed to allowoperandox-ray absorption spectroscopy (XAS) measurements of catalysts. The cell has been developed to operate under standard fuel cell conditions, with elevated temperatures and humidification of the gas-phase reactants, both of which greatly impact the catalyst utilisation. X-ray windows in the endplates of the cell facilitate collection of XAS spectra during fuel cell operation while maintaining good compression in the area of measurement. Results of polarisation curves and cyclic voltammograms showed that theoperandocell performs well as a fuel cell, while also providing XAS data of suitable quality for robust XANES analysis. The cell has produced comparable XAS results when performing a cyclic voltammogram to an establishedin situcell when measuring the Pt LIII edge. Similar trends of Pt oxidation, and reduction of the formed Pt oxide, have been presented with a time resolution of 5 s for each spectrum, paving the way for time-resolved spectral measurements of fuel cell catalysts in a fully-operating fuel cell.

Preoperative Evaluation of Craniopagus Twins: Anatomy, Imaging Techniques, and Surgical Management

Craniopagus twins are a rare congenital malformation in which twins are conjoined at the head. Although there is high prenatal and postnatal mortality for craniopagus twins, successful separation has become more common due to advances in neuroimaging, neuroanesthesia, and neurosurgical techniques. Joined brain tissue, shared arteries and veins, and defects in the skull and dura make surgery technically challenging, and neuroimaging plays an important role in preoperative planning. Drawing on our experience from consultation for multiple successful separations of craniopagus twins, we discuss what radiologists need to know about the anatomy, classification, imaging techniques, and surgical management of craniopagus twins.

Carbon nitrides: synthesis and characterization of a new class of functional materials

We examine the characterization of carbon nitrides and provide a perspective on their functional properties as next-generation materials.

[Role of leptin and leptin resistance in non-alcoholic fatty liver disease development in persons with obesity and overweight]

AIM

To study the impact of leptin and leptinresistance on formation of non-alcoholic fatty liver disease (NAFLD) of people with obesity and overweight.

METHODS

105 patients with obesity and overweight were examined, among them 19 men and 86 women, median age 58 (50-63) years. Risk factors development NAFLD, anthropometric indices, biochemical analysis of blood, abdominal ultrasonic studies, levels leptin and its soluble receptor were estimated. examined people with NAFLD were included into 2 groups: main group (patients NAFLD, n = 77) and comparison group (n = 28).

RESULTS

Waist volume, body mass index, blood glucose were higher in group of patients with NAFLD (p < 0.0001, p < 0.003, p < 0.00002, level) and had positive connection with the change in liver development (rs = (0.376), p < 0.00008, rs = (0.293), p < 0.002, rs = (0.417), p < 0.00001, level). Leptin has direct dependence (rs = (0.291), p < 0.027), while level of soluble receptors to leptin was of reverse dependence (rs = (-0.456), p < 0.0003) on the degree of body weight. Between these indicators in the group with obesity and overweight negative correlation of moderate strength (rs = (-0.370), p < 0.004) was revealed. There were tendencies to a higher level leptin and lower level receptor to leptin in group with NAFLD (median level leptin 29.20 (12.63-44.98) in main group against 27.49 (12.05-54.79), median receptor to leptin 18.25 (14.69-24.26) against 22.05 (14.57-32.04), respectively). However these indicators in the main group also had a negative correlation bond of moderate strength (rs = (-0.384), p < 0.007).

CONCLUSION

Development of NAFLD are associated with obesity and excess body weight, phenomenon of leptinresistance arises to patients with obesity and can be considered as predictor of the development and progression of NAFLD among this category of patients.

Radiation dose for 345 CT-guided interlaminar lumbar epidural steroid injections

BACKGROUND AND PURPOSE

CT guidance is increasingly being used to localize the epidural space during epidural steroid injections. A common concern is that CT may be associated with significantly higher radiation doses compared with conventional fluoroscopy. The goal of this retrospective study was to determine the average dose-length product and effective dose delivered while interlaminar epidural steroid injections are performed and allow comparison with other modalities.

MATERIALS AND METHODS

A total of 281 patients who had undergone 345 consecutive CT-guided epidural steroid injections of the lumbar spine were evaluated for radiation exposure. The dose-length product for each scan was derived from the CT dose index volume and scan length. Effective dose was then calculated from the dose-length product and a κ coefficient of 0.015. Procedure time was calculated from the PACS time stamp on the scout image to the last CT image of the last image series.

RESULTS

The average dose-length product across all procedures was 89.6 ± 3.33 mGy·cm, which represents an effective dose of 1.34 ± 0.05 mSv. No complications from the procedure were observed, and average procedure time was 8 minutes.

CONCLUSIONS

The use of a stationary table and an intermittent scanning technique allow for short procedures and doses that are significantly lower than those of conventional diagnostic CT scans. Furthermore, because CT dose index overestimates radiation dose in stationary table procedures, the actual radiation dose may be even lower than stated here.

Lateral decubitus positioning for cervical nerve root block using CT image guidance minimizes effective radiation dose and procedural time

BACKGROUND AND PURPOSE

Cervical steroid injections are a minimally invasive means of providing pain relief to patients with cervical radiculopathy. CT guidance offers many potential advantages. We developed a technique with the patient in the lateral position with a lateral needle trajectory to minimize the required needle depth from skin to target and a near-vertical needle trajectory. The aim of this study was to analyze the cohort for complications, procedural time, and effective radiation dose.

MATERIALS AND METHODS

This was a retrospective evaluation of a single-center patient cohort. PACS images from the procedures were reviewed for needle depth, procedural time, and CTDI(vol). An anatomically relevant conversion factor was used to calculate the effective dose.

RESULTS

One hundred sixteen cases from 110 patients were identified. The average patient age was 55 years. There were no complications. In 50% of cases, C5-6 was targeted. The average time was 6 minutes, and the average effective radiation dose, 0.51 mSv (0.21-2.56 mSv). Needle-insertion length from the skin to the target was highly correlated with a need for >3 needle repositioning adjustments and scan series (ρ = 0.52, P < .001) and increased procedural time (ρ = 0.42, P < .001). The angle of needle insertion relative to the floor was significantly correlated with an increased number of needle adjustments for depths >25 mm and a longer procedural time (ρ = 0.29, P = .01) but not for depths <25 mm.

CONCLUSIONS

The lateral patient position with CT guidance is safe and allows use of a short needle in a vertical trajectory. This reduces the number of needle adjustments and imaging series to provide a short procedural time with a low effective radiation dose from the procedure.

Prevalence of hippocampal malrotation in a population without seizures

BACKGROUND AND PURPOSE

Hippocampal malrotation (HIMAL) is a failure of hippocampal inversion that occurs during normal fetal development and has been seen on MR imaging examinations of people with epilepsy, but it has not been studied in patients without epilepsy. We intended to evaluate the prevalence of HIMAL in MR imaging examinations of patients without seizures to better understand the significance of HIMAL in the population with seizure.

MATERIALS AND METHODS

A total of 497 MR imaging examinations with thin-section imaging through the temporal lobes of patients referred for conditions other than seizures were reviewed. The examinations were performed on 1.5T magnets. Sagittal T1-weighted and coronal T2-weighted images were used to evaluate each MR image for the distinctive features of HIMAL. As previously described in the literature, the criteria for HIMAL include unilateral involvement and incomplete rotation of a hippocampus that is normal in size and signal intensity but abnormally rounded in shape, with blurred inner structure. In addition, ipsilateral findings of an atypical collateral sulcus angle and atypical position and size of the fornix were noted. The corpus callosum is normal, and the temporal lobe remains normal in size, though the temporal horn may appear enlarged.

RESULTS

None of the patients' examinations fulfilled all of the HIMAL criteria. Six studies satisfied 2 or more criteria, which included an abnormally rounded hippocampus and a vertical collateral sulcus. These HIMAL findings were all seen on the left. Forniceal asymmetry was the most prevalent abnormality, with 289 patients manifesting a low position of 1 fornix.

CONCLUSIONS

Hippocampal malrotation is a rare finding in patients without seizures. HIMAL is therefore likely to be a pathologic finding.

Mutations at the GABA receptor selectivity filter: a possible role for effective charges

An important feature of ligand-gated ion channels is their exquisite ability to discriminate between ions. Still, little is known about the mechanisms underlying, or structural determinates of, this ability. We examined the structural elements underlying the ionic selectivity of rho1 GABA receptors expressed in Xenopus oocytes and human embryonic kidney cells using site-directed mutagenesis and two-electrode voltage-clamp or patch-clamp techniques. The wild-type GABA receptor was chloride selective, with a small but significant permeability to potassium (PNa+ : PK+ : PCl- = 0 : 0.03 :1). Mutation of an alanine to glutamate at position 291 (thought to be located at the intracellular end of the second transmembrane domain), formed a channel that exhibited little discrimination among ions (0.70:0.87:1), while deletion of a neighbouring proline (290) was chloride selective, but had elevated cation permeabilities compared to the wild-type channel (0.12 : 0.14 : 1). Together, the two mutations (DeltaP290/A291E) caused a reversal of selectivity (2.72 : 3.59 : 1). We also examined the effects of neutralizing and reversing the charge of the adjacent, and highly conserved, arginine. Mutation of the neighbouring arginine to glutamate (R292E) increased the cation permeability similar to the DeltaP290/A291E double mutant (2.4 : 3.0 : 1), whereas neutral mutations at this position (R292M or R292C) retained chloride selectivity (0 : 0.11 : 1.0 and 0 : 0.14 : 1.0, respectively). Our experiments suggest that the effective charge near the presumed intracellular mouth of the pore is critical for ionic selectivity.

Development of a photofragmentation laser-induced-fluorescence laser sensor for detection of 2, 4, 6-trinitrotoluene in soil and groundwater

Laser photofragmentation (PF) and subsequent nitric oxide (NO) laser-induced fluorescence (LIF) have been developed to measure the concentration of energetic materials (EM's), such as 2, 4, 6-trinitrotoluene (TNT), in soil and other media. Gas-phase EM's photodissociate, releasing NO(2), when exposed to laser radiation near 226 nm. Laser-excited NO(2) predissociates to form NO that gives an intense fluorescence when excited near 226 nm. The EM concentration is inferred from the intensity of the NO fluorescence. A PF-LIF laser-based sensor is being developed to be used with the U.S. Army Corps of Engineers' Waterways Experiment Station's cone penetrometer to measure in situ the concentration of subsurface TNT. Several factors that affect the PF-LIF signal waveforms, such as sample temperature, laser power, and heating time, were investigated. Also, effects on the PF-LIF signal of adding water and fertilizer to the TNT mixtures were studied. Decay times were determined by least-squares fitting of the exponential PF-LIF signal waveforms. The use of PF-LIF waveforms promises to enable diagnostics of the sample's characteristics that would otherwise not be possible in situ.

Byzantine physicians and their hospitals

Byzantine medicine was organized around hospitals. By the eleventh and twelfth centuries, the best physicians of Constantinople treated their patients either in hospitals or in walk-in dispensaries which formed part of the hospital facilities. Byzantine hospitals were thus medical institutions. This article will review the evidence for this conclusion and introduce two new texts dealing with hospitals in Constantinople. The article will close by suggesting avenues for future research, especially regarding hospitals in provincial cities.

High correlation with survival of proliferating cell nuclear antigen expression in mucoepidermoid carcinoma of the parotid gland

We tested the hypothesis that proliferating cell nuclear antigen can predict survival in patients with mucoepidermoid carcinoma. Formalin-fixed, paraffin-embedded, tissue resected specimens from 43 patients with no prior treatment for mucoepidermoid carcinoma of the parotid gland were immunostained with the PC10 monoclonal antibody to proliferating cell nuclear antigen with the peroxidase/antiperoxidase method. Proliferating cell nuclear antigen levels were defined as the number of nuclei with strong immunostaining divided by the total cell count and were expressed as percentages. Both univariate and multivariate analyses were performed on 12 additional prognostic variables to determine the relative proliferating cell nuclear antigen level to predict survival. The median proliferating cell nuclear antigen level was 7. Five percent of patients with proliferating cell nuclear antigen levels less than 7 died of their disease compared with 48% of those with proliferating cell nuclear antigen levels of 7 or more. Multivariate analysis indicates proliferating cell nuclear antigen to be the most important parameter in predicting survival. Thus the measurement of proliferating cell nuclear antigen is a useful predictor of survival for patients with mucoepidermoid carcinoma of the parotid gland.