Effect of the width of the spacer layers on the size of the bistability region in the current-voltage characteristics of two-barrier tunnel resonance diodes

This paper discusses the question of how the size of the spacer layers affects the position and width of the bistability region in the current-voltage characteristics of tunnel resonance diodes. The current-voltage characteristics were calculated in terms of the self-consistent effective-mass approximation. Increasing the size of the spacer layers shifts the lower boundary of the bistability region upwards so that this region becomes narrower and then completely disappears. Pis’ma Zh. Tekh. Fiz. 23, 12–16 (November 12, 1997)     

MM-Wave integrated phased arrays with ferrite control

A new class of electrically scanned antenna arrays for the millimeter wave range is described. The antenna is based on a planar integrated ferrite travelling wave structure and is controlled by the magnetization of ferrite elements. Experimental antennas operating in the 8-mm wave range have the following electrical parameters: beamwidth 2 to 4°, two dimensional scanning ±20°, loss about 3 to 4 dB     

Effect of γ-radiation in the quality of high-molecular sulfite cellulose

Conclusions The effect of ionizing radiation on the molecular weight characteristics and ability to be dissolved of high-molecular, high-viscosity sulfite cellulose has been investigated.A radiation dose range of 5–10 kGy has been established, on absorption of which by high-molecular, high-viscosity sulfite cellulose, the degree of polymerization is reduced to 840. The reactivity is increased to 80/11 (% CS₂/% NaOH) and the share of the main fraction, having a DP of 200–800, rises to 52–60%. Irradiation of cellulose is suitable for use in the manufacture of viscose fibre.Translated from Khimicheskie Volokna, No. 1, pp. 30–31, January–February, 1988.     

Focused Ultrasound Enabled Trans‐Blood Brain Barrier Delivery of Gold Nanoclusters: Effect of Surface Charges and Quantification Using Positron Emission Tomography

Focused ultrasound (FUS) technology is reported to enhance the delivery of ⁶⁴Cu‐integrated ultrasmall gold nanoclusters (⁶⁴Cu‐AuNCs) across the blood‐brain barrier (BBB) as measured by positron emission tomography (PET). To better define the optimal physical properties for brain delivery, ⁶⁴Cu‐AuNCs with different surface charges are synthesized and characterized. In vivo biodistribution studies are performed to compare the individual organ uptake of each type of ⁶⁴Cu‐AuNCs. Quantitative PET imaging post‐FUS treatment shows site‐targeted brain penetration, retention, and diffusion of the negative, neutral, and positive ⁶⁴Cu‐AuNCs. Autoradiography is performed to compare the intrabrain distribution of these nanoclusters. PET Imaging demonstrates the effective BBB opening and successful delivery of ⁶⁴Cu‐AuNCs into the brain. Of the three ⁶⁴Cu‐AuNCs investigated, the neutrally charged nanostructure performs the best and is the candidate platform for future theranostic applications in neuro‐oncology.     

ITER tungsten divertor design development and qualification program

In November 2011, the ITER Council has endorsed the recommendation that a period of up to 2 years be set to develop a full-tungsten divertor design and accelerate technology qualification in view of a possible decision to start operation with a divertor having a full-tungsten plasma-facing surface. To ensure a solid foundation for such a decision, a full tungsten divertor design, together with a demonstration of the necessary high performance tungsten monoblock technology should be completed within the required timescale. The status of both the design and technology R&D activity is summarized in this paper.     

Study of the CL-20 flame structure using probing molecular beam mass spectrometry

The CL-20 flame structure at pressures of 0.1 and 0.5 MPa was studied using probing molecular beam mass spectrometry. At a pressure of 0.1 MPa, the gaseous products near the surface of the foamy carbonaceous carcass were found to contain eight species: NO, NO₂, CO, CO₂, N₂, H₂O, HCN, and HNCO. At a pressure of 0.5 MPa, NO₂ was not found and the concentration profiles of the remaining seven species were measured versus the distance to the carbonaceous carcass. In the CL-20 flame at a pressure of 0.5 MPa, consumption of N₂ and CO₂ with the formation of NO and HNCO occurred in a zone of width ≈0.8 mm from the surface of the carbonaceous carcass. At a pressure of 0.5 MPa, the composition of the gaseous combustion products of CL-20 at a distance of 3–4 mm differed from the composition at thermodynamic equilibrium. Key words: flame structure, CL-20, probing molecular beam mass spectrometry. __________ Translated from Fizika Goreniya i Vzryva, Vol. 45, No. 3, pp. 58–65, May–June, 2009.     

Mechanism of multiple pulse formation in the normal dispersion regime of passively mode-locked fiber ring lasers

We identify the spectral gain filtering as a mechanism of multiple pulse formation in a fiber laser passively mode-locked through nonlinear polarization rotation operating in the normal dispersion regime. A correlation is theoretically established between the spectral gain bandwidth and the possibility for the laser to deliver several pulses by cavity round-trip: narrow spectrum favours multiple pulsing. Moreover the model allows to show that spectral loss or gain filtering are equivalent with respect to their consequences on the multiple pulsing regime. Experimental results obtained with an erbium-doped fiber laser and an ytterbium-doped fiber laser confirm the theoretical calculations. In addition, an indirect confirmation of the influence of the spectral filtering is proposed using an experimental setup involving a unique laser.