Optimization of acoustic coupling for bottom actuated scattering based subsurface scanning probe microscopy.

The characterization of buried nanoscale structures nondestructively is an important challenge in a number of applications, such as defect detection and metrology in the semiconductor industry. A promising technique is Subsurface Scanning Probe Microscopy (SSPM), which combines ultrasound with Atomic Force Microscopy (AFM). Initially, SSPM was used to measure the viscoelastic contrast between a subsurface feature and its surrounding medium. However, by increasing the ultrasonic frequency to >1 GHz, it has been shown that SSPM can also measure acoustic impedance based contrasts. At these frequencies, it becomes difficult to reliably couple the sound into the sample such that the AFM is able to pick up the scattered sound field. The cause is the existence of strong acoustic resonances in the sample, the transducer, and the coupling layer-the liquid layer used to couple the sound energy from the transducer into the sample-in combination with the nonlinearity of the tip-sample interaction. Thus, it is essential to control and measure the thickness of the coupling layer with nanometer accuracy. Here, we present the design of a mechanical clamp to ensure a stable acoustic coupling. Moreover, an acoustic method is presented to measure the coupling layer thickness in real-time. Stable coupling layers with thicknesses of 700 ± 2 nm were achieved over periods of 2-4 h. Measurements of the downmixed AFM signals showed stable signal intensities for >1 h. The clamp and monitoring method introduced here makes scattering based SSPM practical, robust, and reliable and enables measurement periods of hours.

Sonography guided lumbar nerve and facet blocks: The first report of clinical outcome from Iran.

INTRODUCTION: Nerve root block (NRB) and facet block (FB) are viable options for pain arising from facet and lumbar disc herniation (LDH) not responding to conservative therapy but still not suitable for surgery. Classically, they are performed under fluoroscopy and computed tomography (CT) guidance, which have the disadvantages of radiation exposure and limited accessibility. The aim of this study was to assess the effectiveness of US guided FB and NRB in patients suffering from facet arthropathy and LDH. METHODS: 14 patients were involved in the study. After defining nerve root (for NRB) or facet joints (for FB) under a standard US investigation, real-time injection of methylprednisolone and bupivacaine was performed. Pain was measured before and after procedure by VAS. RESULTS: Ten patients underwent FBs (8 bilateral and 2 unilateral) and 4 underwent NRBs (2 bilateral and 2 unilateral). 11/14 (79%) patients improved after the block (8 in FB, 3 in NRB) and the VAS had significantly decreased 1 week after procedure (mean [range] -1.7 [-6 to 0]). For the 11 patients that improved after FB or NRB, the effect lasted for a mean of 59 days (range: 30-130 days). Analysis showed that neither block procedure (NRB vs. FB) nor block level (L4L5 vs. L5S1) had an effect on result. CONCLUSIONS: Results of our preliminary study shows that in appropriately selected patients, nerve root and facet blocks can be effectively performed under ultrasonography guidance without notable complications, with effects lasting for a mean 2 months.

Evaluation of removal efficiency of residual diclofenac in aqueous solution by nanocomposite tungsten-carbon using design of experiment.

Wastewater containing pharmaceutical residual components must be treated before being discharged to the environment. This study was conducted to investigate the efficiency of tungsten-carbon nanocomposite in diclofenac removal using design of experiment (DOE). The 27 batch adsorption experiments were done by choosing three effective parameters (pH, adsorbent dose, and initial concentration) at three levels. The nanocomposite was prepared by tungsten oxide and activated carbon powder in a ratio of 1 to 4 mass. The remaining concentration of diclofenac was measured by a spectrometer with adding reagents of 2, 2'-bipyridine, and ferric chloride. Analysis of variance (ANOVA) was applied to determine the main and interaction effects. The equilibrium time for removal process was determined as 30 min. It was observed that the pH had the lowest influence on the removal efficiency of diclofenac. Nanocomposite gave a high removal at low concentration of 5.0 mg/L. The maximum removal for an initial concentration of 5.0 mg/L was 88.0% at contact time of 30 min. The results of ANOVA showed that adsorbent mass was among the most effective variables. Using DOE as an efficient method revealed that tungsten-carbon nanocomposite has high efficiency in the removal of residual diclofenac from the aqueous solution.

Sub-50 nm metrology on extreme ultra violet chemically amplified resist--A systematic assessment.

With lithographic patterning dimensions decreasing well below 50 nm, it is of high importance to understand metrology at such small scales. This paper presents results obtained from dense arrays of contact holes (CHs) with various Critical Dimension (CD) between 15 and 50 nm, as patterned in a chemically amplified resist using an ASML EUV scanner and measured at ASML and TNO. To determine the differences between various (local) CD metrology techniques, we conducted an experiment using optical scatterometry, CD-Scanning Electron Microscopy (CD-SEM), Helium ion Microscopy (HIM), and Atomic Force Microscopy (AFM). CD-SEM requires advanced beam scan strategies to mitigate sample charging; the other tools did not need that. We discuss the observed main similarities and differences between the various techniques. To this end, we assessed the spatial frequency content in the raw images for SEM, HIM, and AFM. HIM and AFM resolve the highest spatial frequencies, which are attributed to the more localized probe-sample interaction for these techniques. Furthermore, the SEM, HIM, and AFM waveforms are analyzed in detail. All techniques show good mutual correlation, albeit the reported CD values systematically differ significantly. HIM systematically reports a 25% higher CD uniformity number than CD-SEM for the same arrays of CHs, probably because HIM has a higher resolution than the CD-SEM used in this assessment. A significant speed boost for HIM and AFM is required before these techniques are to serve the demanding industrial metrology applications like optical critical dimension and CD-SEM do nowadays.

Altered inhibition in the hippocampal neural networks after spreading depression.

Prolonged neuronal depression after spreading depression (SD) is followed by a late cellular and synaptic hyperexcitability. Intra- and extracellular recordings of bioelectrical activities were performed in the rodent hippocampus to investigate the role of γ-aminobutyric acid (GABA)-mediated inhibition in the late hyperexcitable state of SD. The effect of KCl-induced negative DC potential shifts was investigated on extracellularly recorded paired-pulse depression (PPD) and bicuculline-induced afterdischarges as well as intracellularly recorded inhibitory post synaptic potentials (IPSPs) in the hippocampal CA1 area. The results revealed that SD decreased the degree of PPD, enhanced the number and duration of bicuculline-induced afterdischarges, and reduced the amplitude and duration of IPSPs. Application of low concentrations of bicuculline before the induction of SD enhanced the inhibitory effect of SD on IPSPs. Data indicate the contribution of GABA-mediated inhibition to SD-induced delayed hyperexcitability. Modulation of GABA function in the late hyperexcitability phase of SD may play a role in therapeutic management of SD-related neurological disorders.

Design and synthesis of pyrimido[4,5-b][1,4]benzothiazine derivatives, as potent 15-lipoxygenase inhibitors.

A group of 2-substituted pyrimido[4,5-b][1,4]benzothiazines were designed, synthesized, and evaluated as potential inhibitors of 15-lipoxygenase (15-LO). Compounds 4d and 4e showed the best IC50 of 15-LO inhibition (IC50=18 and 34 microM, respectively). All compounds were docked into 15-LO. As a result the sulfur atom was oriented toward the iron atom of the active site of 15-LO. We suggest the interaction of the iron atom is essential for the activity of the inhibitors.

Histocompatibility antigen (HLA) associations with multiple sclerosis in Iran.

Human leukocyte antigen (HLA) types were obtained from 79 Iranian patients with multiple sclerosis and compared with 100 controls. The prevalence of HLA-A24 (30.3% versus 18.0%), HLA-DR2 (43.0% versus 28. 0%) and HLA-DR15 (36.7% versus 23.0%) were significantly increased in multiple sclerosis patients compared with controls. However age at onset, and disease status (relapsing - remitting or primary progressive) did not show an association with any particular HLA type. Multiple Sclerosis (2000) 6 317 - 319