Portable Thomson scattering system for temporally resolved plasma measurements under low density conditions.

We present the development of a portable Thomson scattering diagnostic system allowing simultaneous spatially and temporally resolved plasma property measurements for low density plasmas. The setup uses a compact pulsed Nd:YAG laser (532 nm) as the light source with suppression by two volume Bragg grating notch filters and dispersion with a single-stage spectrometer before measurement with an intensified camera. A key issue is the detailed light collection and how it impacts the sensitivity and elastic light suppression, for which we have investigated two optical configurations, one based on a 7 × 1 linear fiber bundle and the other based on a slit spatial-filter. We find that the configuration with the slit spatial-filter provides a higher sensitivity by a factor of ∼2 along with more uniform spatial response. We have developed a custom pulsed-plasma setup with a modulation at 20 kHz, representative of the Hall thruster breathing mode oscillation, to show the possibility of temporally resolved measurements for electric propulsion applications. We have successfully recorded the variations in electron number density and temperature with sub-mm spatial resolution and capturing ten temporal points over the 50 µs modulation period. The detection limit of electron density (with the spatial-filter configuration) is ∼1.6 × 1017 m-3, which is ∼1/10 of the plasma density in the acceleration channel of Hall thrusters.

PUNICALAGIN AND PUNICALIN SUPPRESS THE ADIPOCYTE DIFFERENTIATION THROUGH THE TRANSCRIPTION FACTORS.

BACKGROUND: Pomegranate is a rich source of many polyphenolic compounds including ellagitannins (punicalagin, punicalin and others). AIM: The effects of punicalagin and punicalin on adipogenesis were investigated in this study. MATERIALS AND METHODS: To examine the effect of punicalagin and punicalin on adipocyte differentiation, various concentrations of punicalagin and punicalin (2-10 µM) were applied to differentiated 3T3-L1 cells. Glyceraldehyde-3-phosphate dehydrogenase (GPDH) activity, Oil red O staining, intracellular triglyceride levels, and gene expressions of transcription factors (Peroxisome proliferator-activated receptor-γ (PPARγ), CCAAT-enhancer-binding proteins-α (C/EBPα), Sterol regulatory element-binding protein 1c (SREBP-1c)) and lipolysis-associated genes (hormone-sensitive lipase (HSL), Perilipin A, tumor necrosis factor-α (TNF-α)) were examined in order to investigate the effects of punicalagin and punicalin on adipocyte differentiation. RESULTS: Punicalagin and punicalin applications caused a continuous decrease in cell size and intracellular triglyceride accumulation. GPDH activity and transcription gene expressions decreased significantly in groups that were applicated punicalagin and punicalin at high concentrations. Punicalagin, but not punicalin, down-regulated the expression of HSL and perilipin A and up-regulated the expression of TNF-α in a dose-dependent manner. In conclusion, both punicalagin and punicalin were able to inhibit the adipocyte differentiation.

Contributed review: quantum cascade laser based photoacoustic detection of explosives.

Detecting trace explosives and explosive-related compounds has recently become a topic of utmost importance for increasing public security around the world. A wide variety of detection methods and an even wider range of physical chemistry issues are involved in this very challenging area. Optical sensing methods, in particular mid-infrared spectrometry techniques, have a great potential to become a more desirable tools for the detection of explosives. The small size, simplicity, high output power, long-term reliability make external cavity quantum cascade lasers (EC-QCLs) the promising spectroscopic sources for developing analytical instrumentation. This work reviews the current technical progress in EC-QCL-based photoacoustic spectroscopy for explosives detection. The potential for both close-contact and standoff configurations using this technique is completely presented over the course of approximately the last one decade.

A cavity ring-down spectroscopy sensor for real-time Hall thruster erosion measurements.

A continuous-wave cavity ring-down spectroscopy sensor for real-time measurements of sputtered boron from Hall thrusters has been developed. The sensor uses a continuous-wave frequency-quadrupled diode laser at 250 nm to probe ground state atomic boron sputtered from the boron nitride insulating channel. Validation results from a controlled setup using an ion beam and target showed good agreement with a simple finite-element model. Application of the sensor for measurements of two Hall thrusters, the H6 and SPT-70, is described. The H6 was tested at power levels ranging from 1.5 to 10 kW. Peak boron densities of 10 ± 2 × 10(14) m(-3) were measured in the thruster plume, and the estimated eroded channel volume agreed within a factor of 2 of profilometry. The SPT-70 was tested at 600 and 660 W, yielding peak boron densities of 7.2 ± 1.1 × 10(14) m(-3), and the estimated erosion rate agreed within ~20% of profilometry. Technical challenges associated with operating a high-finesse cavity in the presence of energetic plasma are also discussed.

Obligatory referral among other factors associated with peritonitis in peritoneal dialysis patients.

AIM: Peritonitis is one of the major comorbidities of peritoneal dialysis (PD) patients. The aim of this study was to concentrate on potential risk factors, including more recently studied ones among the classical ones for peritonitis, in PD patients. MATERIALS AND METHODS: We analysed 109 patients (F/M = 42/67) followed up at least for 3 months in a single centre, a tertiary referral hospital for 360.1 patient years. In the study which is designed as a retrospective cohort study, demographic characteristics, conditions for choosing PD, type of PD treatment, some chemical tests and peritonitis episodes were recorded from the files of the patients. RESULTS: The rate of peritonitis was found to be 0.22 episode/patient year and 22 (20.18%) of the patients had more than one episode. Twenty seven (24.8%) of the patients were allocated to PD due to obligatory reasons. According to multiple regression analysis, the associated factors were found to be PD allocation type (obligatory versus voluntary) (p = 0.04; RR = 2.6), serum albumin level (p = 0.05; RR = 1.2), and anti-hepatitis C Virus Antibody positivity (p = 0.03; RR = 1.6). Frequency of female patients were significantly higher in the group who had multiple episodes (p = 0.01). CONCLUSION: Obligatory referral which can be an indication of loss of motivation for peritoneal dialysis procedures, is thought to be a strong risk factor for peritonitis in PD patients and should be further studied. Patients with multiple episodes had a higher frequency of obligatory referral as expected and additionally, they were higher in number of females when compared to the ones with single episode.

Quartz crystal microbalance-based system for high-sensitivity differential sputter yield measurements.

We present a quartz crystal microbalance-based system for high sensitivity differential sputter yield measurements of different target materials due to ion bombardment. The differential sputter yields can be integrated to find total yields. Possible ion beam conditions include ion energies in the range of 30-350 eV and incidence angles of 0 degrees-70 degrees from normal. A four-grid ion optics system is used to achieve a collimated ion beam at low energy (<100 eV) and a two-grid ion optics is used for higher energies (up to 750 eV). A complementary weight loss approach is also used to measure total sputter yields. Validation experiments are presented that confirm high sensitivity and accuracy of sputter yield measurements.

Single-mode delivery of 250 nm light using a large mode area photonic crystal fiber.

We demonstrate that large mode area (LMA) photonic crystal fibers (PCFs) can be used as single-mode patch-cords for 250 nm laser light. We have studied the transmission of the 250 nm output beam of a frequency-quadrupled diode laser through a triangular structure LMA PCF with 10 microm core. We have achieved single-mode output with coupling loss of 1.8 +/- 0.6 dB and transmission loss of 1.5 +/- 0.2 dB/m. The critical bend loss radius is approximately 6 cm. The transmission loss is compared with published bulk silica measurements. Effects of optically induced damage were observed after prolonged operation and have been studied as function of laser power and time. The optical damage occurs primarily at the fiber input and can be partly ameliorated by cleaving the fiber input. For input power levels of < approximately 0.3 mW stable operation can be achieved for periods of >40 hours which is sufficient for many laboratory based applications. The results show the utility of these fibers for single-mode beam delivery in a spectral region where step-index single-mode fibers are not readily available.

Cavity ring-down spectroscopy sensor for ion beam etch monitoring and end-point detection of multilayer structures.

This contribution reports on the development of in situ sputter monitoring and end-point detection for ion beam etch systems using continuous-wave cavity ring-down spectroscopy (cw-CRDS). The demonstrated system is based on the detection of sputtered manganese atoms using a tunable external cavity diode laser in the vicinity of 403.07 nm. The cw-CRDS system is described and measurements from a manganese-iron target are presented. End-point detection is demonstrated by monitoring the time dependence of manganese concentration for a multilayer target comprised of alternating layers of manganese/iron and titanium. Detection limits are shown to be adequate for today's commercial ion beam sputter systems.

Changing diameters of cerebral vessels with age in human autopsy specimens: possible relationships to atherosclerotic changes.

AIMS/OBJECTIVES: It has been previously recognized that the anatomy of arterial bifurcations influences blood flow and has a significant role in the development of vascular disease. MATERIAL AND METHODS: In the present study, we measured the average diameters of the internal carotid (ICA), anterior cerebral (ACA), and middle cerebral arteries (MCA) in autopsy cases. We also calculated the outflow to inflow area ratios for four distinct age groups and for each gender, using 33 adult autopsies and 7 fetuses. RESULTS: The area ratios decreased with age in both male and female samples. The decrease in the male (30%, p<0.05) was greater than the decrease for the female (17%, p > 0.05). The average diameter of the ACA, MCA and ICA of both female and male cases increased up to the 25-44 age group, decreased for the 45-64 age group, with a second increase above the age of 65. CONCLUSIONS: The decrease in the area ratios and the pattern of changes of the dimensions of the cerebral vessels with age are useful to examine the causal relationships of these pathologic conditions and raises novel questions about age and gender differences in the structure of the intracranial vessels.

Velocity measurements by cavity ringdown spectroscopy.

We demonstrate velocity measurements of gas-phase particles by using cavity ringdown spectroscopy (CRDS). Velocity information is inferred from the Doppler-shift contributions to the measured absorption line shape. Because in CRDS the laser beam propagates back and forth within the optical cavity, a measured absorption feature is both upshifted and downshifted; i.e., it is split by the velocity component parallel to the optical axis. The splitting of the absorption features allows direct velocity measurements to be made without requiring an external frequency reference. The CRDS velocity measurement approach is demonstrated for sputtered molybdenum atoms in a low-pressure (collisionless) environment.

Detection of sputtered metals with cavity ring-down spectroscopy.

We report on use of cavity ring-down spectroscopy (CRDS) as a means to detect and quantify ion sputtering of refractory metal species. CRDS measurements are made with a neodymium:YAG-pumped optical parametric oscillator laser system in the 375-400 nm region. CRDS sputtering measurements are presented for argon ions incident on iron, aluminum, molybdenum, and titanium. The measurements are based on absorption from fine-structure levels of the electronic ground-state multiplets. For each species, characteristic spectra are provided, the dependence of sputtered particle number density on the beam current is examined, measured densities are compared with a sputter model, and detection limits are determined. For iron, aluminum, and titanium we probe multiple fine-structure levels within the ground-state multiplet and obtain information on their relative populations.

The diameters of common carotid artery and its branches in newborns.

The common carotid artery (CCA) bifurcation is of clinical importance due to its vascular access site for intravascular intervention. Additionally, it is also one of the most common sites of atherosclerotic plaque formation. There are numerous studies on the diameters of CCA, internal carotid artery (ICA), and external carotid artery (ECA) in adults, but few studies on newborns. Cadaver and angiographic studies have shown dimensional variations in the carotid arteries within/between individuals and also between different sexes. It is well known that the initial lesions of atherosclerosis begin very early in fetal life. Therefore, it is important to know the anatomical details of the CCA and its branches. In the present study, the neck regions of 20 (11 males and 9 females) fixed newborn cadavers were dissected. The CCAs were cut below the bulb of the carotid bifurcation further; ICA and ECA were cut above the bulb of the carotid bifurcation. The internal diameters of the CCA, ICA, and ECA were measured using a light microscopy. ECA/CCA, ICA/CCA, ICA/ECA ratios, and outflow to inflow area ratio were calculated. The mean outflow to inflow area ratio was 1.14+/-0.28. Our results highly correlated with the defined optimal ratio (1.15). The ECA/CCA, ICA/CCA, and ICA/ECA ratios were 0.78+/-0.12, 0.71+/-0.13, and 0.93+/-0.16, respectively. There were no statistically significant differences between male and female and also between right and left sides. These findings are of importance in understanding the anatomy of carotid artery during newborn period.

Use of hollow-core fibers to deliver nanosecond Nd:YAG laser pulses to form sparks in gases.

We report what is to our knowledge the first delivery of nanosecond laser pulses through flexible fibers to produce optical sparks in atmospheric-pressure gases. Our work employs a Nd:YAG laser beam (1.064 microm) delivered through a cyclic olefin polymer-coated silver hollow fiber. We studied the beam properties at the fiber exit as a function of the fiber launch geometry. We found that for a low-angle launch (approximately 0.01 rad half-angle), the exit beam has relatively high optical intensity (approximately 2 GW/cm2) and low light divergence (approximately 0.01 rad half-angle) and allows downstream spark formation. The effect of fiber bending on the exit beam and on the ability to make sparks is also investigated.

Characterization of laser seeding by use of group-velocity dispersion in an atomic-vapor filter.

A method for measuring laser seeding efficiencies by use of group-velocity dispersion has been developed. By tuning the laser near a resonance in an atomic-vapor filter it is possible to temporally decouple the seeded (narrow-band) light from the unseeded (broadband) light. We measured a seeding efficiency of 99.8% of the third harmonic of an injection-seeded Ti:sapphire laser. A model for the observed dispersion has been developed and tested. The group-velocity dispersion in the filter may also be used to chirp pulses for spectral analysis in the time domain.

Effects of preservation of rat lungs in a hypothermic medium on alveolar morphology.

The increasing use of organs such as liver, lung, heart, pancreas, kidney and small intestine for transplantation purposes necessitates the development of optimum preservation techniques. The aim of our study was to investigate time-related morphological changes in alveoli during preservation of rat lungs in hypothermic Euro-Collins solution. Lungs were perfused via the pulmonary arteries with Euro-Collins solution at a temp of 19 degrees C. Totally perfused lungs were placed in Euro-Collins solution and stored for 6, 12 and 24 h at 4 degrees C. Biopsies were taken and prepared for examination at the light and electron microscopical level. Light microscopic examination revealed good preservation of the alveoli after storage for 6 h and moderate damage of alveolar architecture after 12 h of preservation. Severe degeneration of alveoli was found after 24 h of storage. The main ultrastructural changes were observed in lungs stored for 12 h and 24 h. After 6 h of storage, tissue damage was not found. Pneumocytes type II lost their apical microvilli and lamellar bodies were electron-lucent, indicating lamellar degeneration after 12 and 24 h of storage. Pneumocytes type I were also damaged. Their cytoplasm contained many vacuoles. Endothelial lining of the capillaries was contracted. Endothelial cells also showed many vacuoles. Edema around the capillaries was observed. We conclude on the basis of our morphological study, that Euro-Collins solution at low temperature is a good preservative for a short period of time only, but serious tissue damage occurs after periods of preservation longer than 12 h.

Ultraviolet filtered Rayleigh scattering temperature measurements with a mercury filter.

We report the development of ultraviolet filtered Rayleigh scattering as a diagnostic tool for measurements of gas properties. A frequency-tripled narrow-linewidth Ti:sapphire laser illuminates a sample, and Rayleigh scattered light is imaged through a mercury-vapor absorption filter. Working in the ultraviolet improves the signal-to-noise ratio compared with that previously obtained in the visible as the result of an enhanced scattering cross section as well as the nearly ideal properties of the mercury filter. Tuning the laser through the absorption notch of the filter is a means of probing the scattering line shape, which contains temperature information. Temperature measurements of air are shown to have uncertainties of less than 3%.

Concurrent anomalies of the abdominal arteries: an extremely long coeliac trunk, an inferior phrenic trunk, and an aberrant right hepatic artery.

We present a case in which the branching pattern of the abdominal arteries contains multiple variations that to date have not been reported together. The anomalies encountered include an extremely long coeliac trunk, an inferior phrenic trunk (as one of the branches of the coeliac trunk) and an aberrant (replaced) right hepatic artery derived from the superior mesenteric artery.

Dispersion filter for spectral and spatial resolution of pure rotational Raman scattering.

A new filtering technique for Raman spectroscopy utilizes atomic vapor to suppress strong elastic and Rayleigh scattering while simultaneously resolving individual rotational Raman lines. Filtered images capture high-resolution spectral information in one dimension and spatial resolution in the other dimension. The filter is based on resonance enhanced dispersion, where the index of refraction varies dramatically. In a simple prism geometry the vapor disperses incident radiation according to frequency. A mercury-vapor-based dispersion filter has been fabricated, modeled, and demonstrated to capture pure rotational Raman scattering from CO(2).

A rare case of the posterior inferior cerebellar artery.

The posterior inferior cerebellar artery (PICA) is normally a branch of the vertebral artery. In this rare case, the unilateral left vertebral artery continued its course as the left PICA, and an extremely small caliber left vertebral artery joined the righ vertebral artery to form the basilar artery. This rare feature of the PICA is demonstrated and its relation to neighboring structures is discussed. Also, the literature concerning the PICA is reviewed.