Nanodiamond finding in the hyblean shallow mantle xenoliths.

Most of Earth's diamonds are connected with deep-seated mantle rocks; however, in recent years, µm-sized diamonds have been found in shallower metamorphic rocks, and the process of shallow-seated diamond formation has become a hotly debated topic. Nanodiamonds occur mainly in chondrite meteorites associated with organic matter and water. They can be synthesized in the stability field of graphite from organic compounds under hydrothermal conditions. Similar physicochemical conditions occur in serpentinite-hosted hydrothermal systems. Herein, we report the first finding of nanodiamonds, primarily of 6 and 10 nm, in Hyblean asphaltene-bearing serpentinite xenoliths (Sicily, Italy). The discovery was made by electron microscopy observations coupled with Raman spectroscopy analyses. The finding reveals new aspects of carbon speciation and diamond formation in shallow crustal settings. Nanodiamonds can grow during the hydrothermal alteration of ultramafic rocks, as well as during the lithogenesis of sediments bearing organic matter.

[Low-frequency Raman spectra in water and in weak aqueous solutions. Spatial inhomogeneity in hydrogen peroxide solution].

We describe some examples of the study of intermolecular interactions in water and in weak aqueous solutions using the low-frequency Raman spectra. An improved method of determining parameters of the dynamic susceptibility from the Raman spectra is described. The nine spectral parameters (the intensity, the frequency and the width of the two oscillators, the intensity and the width of the relaxation motion and the intensity of fluorescent background) completely describe the spectrum in the frequency range of 4 to 320 cm(-1). For hydrogen peroxide the dependences of these parameters on the concentration is shown. Concentration dependence of the spectral parameters of the hydrogen peroxide solution in water indicates a change in the structure of the molecular bonds in water near a peroxide molecule at a distance up to 0.7-0.9 nm.The effect of the exciting laser radiation on the parameters of the spectra in the registration of the Raman spectra of water is shown.

Superconductivity in diamond.

Diamond is an electrical insulator well known for its exceptional hardness. It also conducts heat even more effectively than copper, and can withstand very high electric fields. With these physical properties, diamond is attractive for electronic applications, particularly when charge carriers are introduced (by chemical doping) into the system. Boron has one less electron than carbon and, because of its small atomic radius, boron is relatively easily incorporated into diamond; as boron acts as a charge acceptor, the resulting diamond is effectively hole-doped. Here we report the discovery of superconductivity in boron-doped diamond synthesized at high pressure (nearly 100,000 atmospheres) and temperature (2,500-2,800 K). Electrical resistivity, magnetic susceptibility, specific heat and field-dependent resistance measurements show that boron-doped diamond is a bulk, type-II superconductor below the superconducting transition temperature T(c) approximately 4 K; superconductivity survives in a magnetic field up to Hc2(0) > or = 3.5 T. The discovery of superconductivity in diamond-structured carbon suggests that Si and Ge, which also form in the diamond structure, may similarly exhibit superconductivity under the appropriate conditions.

[Cytomorphological characteristics of ovarian dysgerminoma]. / Tsitomorfologicheskie priznaki disgerminom iaichnika.

Cytomorphological signs of ovarian dysherminoma are distinguished on suboperation material from 7 patients. Scrapings from removed ovarian tumors were stained after N. G. Alexeev and Pappenheim. Dysherminoma cytograms were characterized mainly by a combination of three cell types: large sharply polymorphic epithelioid with multiple clearly-seen nuclei, connective tissue, and lymphocyte-like cells.