Experimental verification of a self-consistent theory of the first-, second-, and third-order (non)linear optical response

We show that a combination of linear absorption spectroscopy, hyper-Rayleigh scattering, and a theoretical analysis using sum rules to reduce the size of the parameter space leads to a prediction of the two-photon absorption cross-section of the dye AF455 that agrees with two-photon absorption spectroscopy. Our procedure, which demands self-consistency between several measurement techniques and does not use adjustable parameters, provides a means for determining transition moments between the dominant excited states based strictly on experimental characterization. This is made possible by our new approach that uses sum rules and molecular symmetry to rigorously reduce the number of required physical quantities.Comment: 10 pages, 9 figure

Improving of the wear resistance of working parts agricultural machinery by the implementation of the effect of self-sharpening

The failure of the cutting elements of farm machinery is due to the blunting of cutting edges (increase of their radius) till the limit values. The most effective method for increasing the wear resistance of farm machinery is the realization of self-sharpening effect of the cutting elements. The testings took place in laboratory and field at the State Technical University of Kirovograd (Ukraine) in 2015. The technical equipment consists of the consolidated farmer plowshares by different methods as well as their samples, devicesfor measuring the wear resistance and thumbprint plowshares. It was determined the resistance to wear, the radius of curvature and the changing coefficient of the blades shape. The self-sharpening process was examined throughout the experiment.The results showed that the consolidated plowshares by the proposed technology (laser welding of the mixture (PS-14-60 + 6% В4С) compared to the traditional technology (volumetric heat treatment) have a blade radius 2.5 times lower, a wear 2.2 to 2.78 times lower and the self-sharpening process of the plowshares has been observed since the beginning of the wear until the time limit operation. The changing shape coefficient was respectively of 0.98 for the consolidated plowshares with alloy PS-14-60 + 6% B4C and 0.82 for those consolidated by volumetric heat treatment

Model photo-responsive elastomers based on the self-assembly of side group liquid crystal triblock copolymers (Presentation Recording)

We report the synthesis of azobenzene-containing coil-liquid crystal-coil triblock copolymers that form uniform and highly reproducible elastomers by self-assembly. To serve as actuators to (non-invasively) steer a fiber optic, for example in deep brain stimulation, the polymers are designed to become monodomain “single liquid crystal” elastomers during the fiber-draw process and to have a large stress/strain response to stimulation with either light or heat. A fundamental scientific question that we seek to answer is how the interplay between the concentration of photoresponsive mesogens and the proximity to the nematic-isotropic transition governs the sensitivity of the material to stimuli. Specifically, a matched pair of polymers, one with ~5% azobenzene-containing side groups (~95% cyanobiphenyl side groups) and the other with 100% cyanobiphenyl side groups were synthesized from identical triblock pre-polymers (with polystyerene end blocks and 1,2-polybutadiene midblocks). These can be blended in various ratios to prepare a series of elastomers that are precisely matched in terms of the backbone length between physical crosslinks (because each polymer is derived from the same pre-polymer), while differing in % azobenzene side groups, allowing the effect of concentration of photoresponsive groups to be unambiguously determined

Using dark modes for high-fidelity optomechanical quantum state transfer

In a recent publication [Y.D. Wang and A.A. Clerk, Phys. Rev. Lett. 108, 153603 (2012)], we demonstrated that one can use interference to significantly increase the fidelity of state transfer between two electromagnetic cavities coupled to a common mechanical resonator over a naive sequential-transfer scheme based on two swap operations. This involved making use of a delocalized electromagnetic mode which is decoupled from the mechanical resonator, a so-called "mechanically-dark" mode. Here, we demonstrate the existence of a new "hybrid" state transfer scheme which incorporates the best elements of the dark-mode scheme (protection against mechanical dissipation) and the double-swap scheme (fast operation time). Importantly, this new scheme also does not require the mechanical resonator to be prepared initially in its ground state. We also provide additional details on the previously-described interference-enhanced transfer schemes, and provide an enhanced discussion of how the interference physics here is intimately related to the optomechanical analogue of electromagnetically-induced transparency (EIT). We also compare the various transfer schemes over a wide range of relevant experimental parameters, producing a "phase diagram" showing the the optimal transfer scheme for different points in parameter space.Comment: 39 pages, 11 figures NJP 14 (Focus issue on Optomechanics

A quantum mechanical model of the upper bounds of the cascading contribution to the second hyperpolarizability

Microscopic cascading of second-order nonlinearities between two molecules has been proposed to yield an enhanced third-order molecular nonlinear-optical response. In this contribution, we investigate the two-molecule cascaded second hyperpolarizability and show that it will never exceed the fundamental limit of a single molecule with the same number of electrons as the two-molecule system. We show the apparent divergence behavior of the cascading contribution to the second hyperpolarizability vanishes when properly taking into account the intermolecular interactions. Although cascading can never lead to a larger nonlinear-optical response than a single molecule, it provides alternative molecular design configurations for creating materials with large third-order susceptibilities that may be difficult to design into a single molecule.Comment: 13 pages, 9 figures, 1 tabl

МОБІЛЬНИЙ КАЛЬКУЛЯТОР ОЦІНЮВАННЯ ХІМІЧНОГО ЗАРАЖЕННЯ CONTAM

The mobile phone program Contam for the depth of contamination zone and the area of actual and probable contamination calculations during the dangerous chemical substances emission accidents is developed. Input data is the name, quantity and spill thickness of hazardous substance and weather conditions – temperature, wind speed and wind direction. The algorithm of natural logarithm calculation is advanced and included in the program. The recommendations on use of the program by the head of liquidation of an extreme situation is describedРозроблено програму Contam для мобільних телефонів, за допомогою якої обчислюється глибина зони зараження, площі фактичного та можливого зараження під час аварій, пов'язаних з витоком небезпечних хімічних речовин. Вхідними даними є назва та кількість небезпечної речовини, товщина шару розливу та погодні умови – температура, швидкість і напрям вітру. Удосконалено алгоритм обчислення натурального логарифма, який використано у програмі. Наведено рекомендації з використання програми керівником ліквідації надзвичайної ситуації

The MRN complex is transcriptionally regulated by MYCN during neural cell proliferation to control replication stress

The MRE11/RAD50/NBS1 (MRN) complex is a major sensor of DNA double strand breaks, whose role in controlling faithful DNA replication and preventing replication stress is also emerging. Inactivation of the MRN complex invariably leads to developmental and/or degenerative neuronal defects, the pathogenesis of which still remains poorly understood. In particular, NBS1 gene mutations are associated with microcephaly and strongly impaired cerebellar development, both in humans and in the mouse model. These phenotypes strikingly overlap those induced by inactivation of MYCN, an essential promoter of the expansion of neuronal stem and progenitor cells, suggesting that MYCN and the MRN complex might be connected on a unique pathway essential for the safe expansion of neuronal cells. Here, we show that MYCN transcriptionally controls the expression of each component of the MRN complex. By genetic and pharmacological inhibition of the MRN complex in a MYCN overexpression model and in the more physiological context of the Hedgehog-dependent expansion of primary cerebellar granule progenitor cells, we also show that the MRN complex is required for MYCN-dependent proliferation. Indeed, its inhibition resulted in DNA damage, activation of a DNA damage response, and cell death in a MYCN- and replication-dependent manner. Our data indicate the MRN complex is essential to restrain MYCN-induced replication stress during neural cell proliferation and support the hypothesis that replication-born DNA damage is responsible for the neuronal defects associated with MRN dysfunctions.Cell Death and Differentiation advance online publication, 12 June 2015; doi:10.1038/cdd.2015.81