Reversal of crystallization in cryoprotected samples by laser editing.

Advances in cryobiology techniques commonly target either the cooling or the warming cycle, while little thought has been given to ≪repair≫ protocols applicable during cold storage. In particular, crystallization is the dominant threat to cryopreserved samples but proceeds from small nuclei that are innocuous if further growth is forestalled. To this end, we propose a laser editing technique that locally heats individual crystals above their melting point by a focused nanosecond pulse, followed by amorphization during rapid resolidification. As a reference, we first apply the approach to ice crystals in cryoprotected solution and use Raman confocal mapping to study the deactivation of crystalline order. Then, we examine dimethyl sulfoxide trihydrate crystals that can germinate at low temperatures in maximally freeze concentrated regions, as commonly produced by equilibrium cooling protocols. We show how to uniquely identify this phase from Raman spectra and evidence retarded growth of laser-edited crystals during warming.

Multimode LD-pumped all-fiber Raman laser with excellent quality of 2nd-order Stokes output beam at 1019†nm.

A multimode all-fiber Raman laser enabling cascaded generation of high-quality 1019-nm output beam at direct pumping by highly-multimode (M2>30) 940-nm laser diodes has been demonstrated. The laser is made of a 100/140 graded-index fiber with special in-fiber Bragg gratings which secure sequential generation of the 1st (976 nm) and 2nd (1019 nm) Stokes orders. Comparing different 1019-nm cavity structures shows that the half-open cavity with one FBG and distributed feedback via random Rayleigh backscattering provides excellent quality (M2∼1.3) with higher slope efficiency of pump-to-2nd Stokes conversion than in the conventional 2-FBG cavity. The maximum achieved slope efficiency amounts to about 40% at output powers of up to 12 W limited by the 3rd Stokes generation.

Frequency doubling of multimode diode-pumped GRIN-fiber Raman lasers.

Frequency doubling of multimode diode-pumped GRIN-fiber Raman laser with improved beam quality (M2=1.9-2.6 depending on configuration) in a simple single-pass scheme with 5-mm PPLN crystal is studied. After scheme optimization and elimination of back reflection and crystal heating effects, an efficient conversion into blue spectral range with output power of about 0.4 W@488 nm and 0.64 W@477 nm has been demonstrated.

Fifty-ps Raman fiber laser with hybrid active-passive mode locking.

Actively mode locked Raman lasing in a ring PM-fiber cavity pumped by a linearly polarized Yb-doped fiber laser is studied. At co-propagating pumping, a stochastic pulse with duration defined by the AOM switching time (~15 ns) is generated with the round-trip period. At counter-propagating pumping, one or several sub-ns pulses (within the AOM switching envelope) are formed. It has been found that the formation of such stable multi-pulse structure is defined by the single-pulse energy limit (~20 nJ) set by the second-order Raman generation. Adding a NPE-based saturable absorber in the actively mode locked cavity, results in sufficient shortening of the generated pulses both in single- and multi-pulse regimes (down to 50 ps). A model is developed adequately describing the regimes.

[Characteristics of the formation, course and treatment of alcohol dependence in patients with posttraumatic stress disorder].

This article presents the results of a study of clinical features of the development and course of alcohol dependence in patients with posttraumatic stress disorder (PTSD) in comparison with alcohol-dependent patients without PTSD. The highly progressive course, continuous alcohol consumption, high alcohol tolerance, rapidly emerged altered forms of alcohol intoxication, alcohol amnesias, alcohol withdrawal with the prevalence of psychopathological component, and more pronounced social and somatic consequences of alcohol abuse were characteristic of the PTSD group. At the same time, the alcohol-dependent patients with PTSD had the best outcome to the end of 12-month treatment with intramuscular injections of vivitrol.

[Alcohol dependence and mental adaptation disorders (the use of injectable extended-release naltrexone)].

This review of literature describes a role of chronic stress in the development of substance dependence including alcohol dependence. It is focused on neurochemical mechanisms of this dependence and approaches to its treatment in people with mental adaptation disorders. An example of treatment with injectable extended-release naltrexone is presented.