Dinitro Trifurazans with Oxy,Azo, and Azoxy Bridges

The search of the new low-melting high energetic materials, which match the performance of TNAZ and more available, is the barest necessity. The syntheses of several novel zero-hydrogen but nitrogen and oxygen rich high energetic heterocycles, such as bridged nitrofurazans, were undertaken to test the hypothesis that accumulate furazan ring in such molecule could effectively serve in construction of energetically interesting materials. Eight dinitro trifurazans were synthesized and tested. The series of compounds was prepared in three--five stages from the 3,4-diaminofurazan( 10 ). Oxy bridge was formed by utilizing hydroxyfurazans as nucleophiles. Azo bridge was prepared by oxidizing coupling of amino groups with KMnO₄ in acid medium. Transformation of azo bridge to azoxy one was accomplished by mixture of(NH₄)₂S₂O₈ and oleum. The set of trifurazans represents a new class of low-melting high energetic materials which are among the most potent C_xH_yN_zO_w-explosives known. The isomeric diazoxyfurazans,( 28 ),( 29 ), and( 30 ), differ dramatically in their properties. Liquid diazoxy compound( 28 ) has density of 1.8 g/cm³ and is reach a record figure for C_xH_yN_zO_w-oil known.     

Effect of Humid Air Exposed to IR Radiation on Enzyme Activity

Water vapor absorbs well in the infra-red region of the electromagnetic spectrum. Absorption of radiant energy by water or water droplets leads to formation of exclusion zone water that possesses peculiar physico-chemical properties. In the course of this study, normally functioning and damaged alkaline phosphatase, horseradish peroxidase and catalase were treated with humid air irradiated with infrared light with a wavelength in the range of 1270 nm and referred to as coherent humidity (CoHu). One-minute long treatment with CoHu helped to partially protect enzymes from heat inactivation, mixed function oxidation, and loss of activity due to partial unfolding. Authors suggest that a possible mechanism underlying the observed effects involves altering the physicochemical properties of aqueous media while treatment of the objects with CoHu where CoHu acts as an intermediary.     

Role of Nano-miRNAs in Diagnostics and Therapeutics

MicroRNAs (miRNA) are key regulators of gene expression, controlling different biological processes such as cellular development, differentiation, proliferation, metabolism, and apoptosis. The relationships between miRNA expression and the onset and progression of different diseases, such as tumours, cardiovascular and rheumatic diseases, and neurological disorders, are well known. A nanotechnology-based approach could match miRNA delivery and detection to move beyond the proof-of-concept stage. Different kinds of nanotechnologies can have a major impact on the diagnosis and treatment of miRNA-related diseases such as cancer. Developing novel methodologies aimed at clinical practice represents a big challenge for the early diagnosis of specific diseases. Within this context, nanotechnology represents a wide emerging area at the forefront of research over the last two decades, whose potential has yet to be fully attained. Nanomedicine, derived from nanotechnology, can exploit the unique properties of nanometer-sized particles for diagnostic and therapeutic purposes. Through nanomedicine, specific treatment to counteract only cancer-cell proliferation will be improved, while leaving healthy cells intact. In this review, we dissect the properties of different nanocarriers and their roles in the early detection and treatment of cancer.     

Intense polarized atomic deuteron source

An intense polarized deuteron gas jet, to be used as a target in an electron storage ring, is described.With a gas flow of 0.3 1 Torr/s through a nozzle, the flux of polarized atoms from a separation magnet is Q = 1.5 × 10¹⁶ atoms/s. At a distance of 45 cm from the magnet the jet width, at half-height, is 6 mm and the target thickness t = 2 × 10¹¹ atoms/cm². The degree of tensor polarization is P_zz = ?0.75 ± 0.10 for the 3 → 5 transition and P_zz = 0.80 ± 10 for the 2 → 6 transition.     

Thermal desorption of fullerene C60 from polymer matrices

The data on thermally stimulated desorption (TSD) study of fullerene C₆₀ molecules from different polymer matrices are compared in view of the temperature positions and relative intensities of resolved thermal desorption stages. An increase of the low temperature C₆₀ desorption stages is observed for polydimethylsiloxane (PDMS) and polystyrene (PS) contrary to polyimide (PI). This is in agreement with the difference in glass transition temperatures (T_g) of these polymers. The TSD data allow us to conclude that above T_g of the polymer the solubility of fullerene C₆₀ in PDMS and PS is up to the order of magnitude higher compared with C₆₀ solubility in low molecular weight solvents.     

Photovoltaic Ge/Si quantum dot detectors operating in the mid-wave atmospheric window (3-5 micrometers)

ABSTRACT: Ge/Si quantum dots fabricated by molecular-beam epitaxy at 500C are overgrown with Si at different temperatures Tcap, and effect of boron delta-doping of Si barriers on the mid-infrared photoresponse was investigated. The photocurrent maximum shifts from 2.3 to 3.9 micrometer with increasing Tcap from 300 to 750C. Within the sample set, we examined devices with different positions of the delta-doping layer with respect to the dot plane, different distances between the delta-doping layer and the dot plane d, and different doping densities pB. All detectors show pronounced photovoltaic behavior implying the presence of an internal inversion asymmetry due to the placing dopants in the barriers. The best performance was achieved for the device with Tcap=600C, pB=12x10^{11} cm^{-2}, and d=5 nm in a photovoltaic regime. At a sample temperature of 90K and no applied bias, a responsivity of 0.83 mA/W and detectivity of 8x10^{10} cmHz^{1/2}/W at lambda=3.4 micrometer were measured under normal incidence infrared radiation.     

Assessing graphene nanopores for sequencing DNA

Using all-atom molecular dynamics and atomic-resolution Brownian dynamics, we simulate the translocation of single-stranded DNA through graphene nanopores and characterize the ionic current blockades produced by DNA nucleotides. We find that transport of single DNA strands through graphene nanopores may occur in single nucleotide steps. For certain pore geometries, hydrophobic interactions with the graphene membrane lead to a dramatic reduction in the conformational fluctuations of the nucleotides in the nanopores. Furthermore, we show that ionic current blockades produced by different DNA nucleotides are, in general, indicative of the nucleotide type, but very sensitive to the orientation of the nucleotides in the nanopore. Taken together, our simulations suggest that strand sequencing of DNA by measuring the ionic current blockades in graphene nanopores may be possible, given that the conformation of DNA nucleotides in the nanopore can be controlled through precise engineering of the nanopore surface.