Efficient guiding and focusing of intense laser pulse using periodic thin slits

Slits have been widely used in laser-plasma interactions as plasma optical components for generating high-harmonic light and controlling laser-driven particle beams.Here,we propose and demonstrate that periodic thin slits can be regarded as a new breed of optical elements for efficient focusing and guiding of intense laser pulse.The fundamental physics of intense laser interaction with thin slits is studied,and it is revealed that relativistic effects can lead to enhanced laser focusing far beyond the pure diffractive focusing regime.In addition,the interaction of an intense laser pulse with periodic thin slits makes it feasible to achieve multifold enhancement in both laser intensity and energy transfer efficiency compared with conventional waveguides.These results provide a novel method for manipulating ultra-intense laser pulses and should be of interest for many laser-based applications.

The Role of the Size Effect on the Drying of Refractory Castables—How Its Under-standing Could Narrow the Gap between Laboratory Studies and Industrial Reality

Refractories have unique capabilities such as sustaining their shape and properties at extreme conditions such as the combination of high temperatures and thermal shock,contact with molten metals and slags and in some circumstances resistance to erosion from abrasive particles.Given the large processing output of the heavy industries such as the cement and steel ones which both require high temperature processes,the refractories structures span various meters and weight of several tons.As the water removal stage of hydraulic bonded castables in industrial sites takes hours(10-60 h)due to the risk of explosive spalling,efforts to mitigate it are commonly studied.This has provided theoretical understanding of the general aspects of drying and important tools,such as the thermogravimetry analysis(TGA),for the design of refractory compositions with higher explosive spalling resistance.However,the optimization of this process is still far from the industrial reality especially because the actual linings that require the drying are orders of magnitude larger than the samples considered in the laboratory tests.Therefore,this study proposed the analysis of the sample volume effect on the water removal dynamics through TGA of high alumina castables with calcium aluminate cement.Conventionalφ5 cm×5 cm cylindrical samples were assessed in a laboratory scale equipment whereas macro TGA were carried out considering 20 cm×20 cm×20 cm and 30 cm×30 cm×30 cm cubic samples.Additionally,the effect of polymeric fibers was also considered.It was found out that the different thermal gradients within the macro TGA samples resulted in an inflection on the sample’s heating rate and that the mass loss was affected by the volume considered,especially for the composition without additives.These findings highlight the requirement of carefully taking into consideration the different dimensional sizes and thermal gradients in the samples when analyzing and interpreting the laboratory studies,and especially when trying to extrapolate such results to the industrial reality.

Microstructure and mechanical properties of Mg-to-Al dissimilar welded joints with an Ag interlayer using ultrasonic spot welding

Lightweight ZEK100-0 Mg alloy and A16022-T43 Al alloy with an Ag interlayer were joined via ultrasonic spot welding(USW),focusing on the microstructural change and tensile lap shear strength of the welded joints in relation to welding energy.Mg/Al interface was superseded by Mg/Ag and Al/Ag interfaces,and unfavorable Mg门A-intermetallic compound was eliminated.Ag foil was observed to be intact in the nugget center,while it was broken or dissolved at the nugget edge at high welding energy levels.The diffusion layer at the Mg/Ag interface consisted of two distinctive sub-layers:Mg3Ag intermetallic compound adjoining Ag foil,and Mg3Ag-l-Mg eutectic structure adjacent to Mg.Only a thin diffusion layer consisting mainly of Ag3Al occurred al lhe Al/Ag interface.The tensile lap shear strength first increased,reached its peak value,and then decreased with increasing welding energy.The shear strength achieved in the present study was〜31%higher than that of the joint without interlayer.Interfacial failure occurred at all energy levels,with Ag foil particles or fragments being stuck on both Mg and Al sides due to its intense interaction with Mg and Al via accelerated diffusion during USW.The results obtained pave the way for the challenging dissimilar welding between Mg and Al alloys.

Plasma optics in the context of high intensity lasers

The use of plasmas provides a way to overcome the low damage threshold of classical solid-state based optical materials,which is the main limitation encountered in producing and manipulating intense and energetic laser pulses.Plasmas can directly amplify or alter the characteristics of ultra-short laser pulses via the three-wave coupling equations for parametric processes.The strong-coupling regime of Brillouin scattering(sc-SBS)is of particular interest:recent progress in this domain is presented here.This includes the role of the global phase in the spatio-temporal evolution of the three-wave coupled equations for backscattering that allows a description of the coupling dynamics and the various stages of amplification from the initial growth to the so-called self-similar regime.The understanding of the phase evolution allows control of the directionality of the energy transfer via the phase relation between the pulses.A scheme that exploits this coupling in order to use the plasma as a wave plate is also suggested.

The Role of TNF Related Apoptosis-Inducing Ligand in Neurodegenerative Diseases

A hallmark of all forms of neurodegenerative diseases is impairment of neuronal functions,and in many cases neuronal cell death.Although the etiology of neurodegenerative diseases may be distinct,different diseases display a similar pathogenesis,for example abnormal immunity within the central nervous system(CNS),activation of macrophage/microglia and the involvement of proinflammatory cytokines.Recent studies show that neurons in a neurodegenerative state undergo a highly regulated programmed cell death,also called apoptosis.TNF-related apoptosis-inducing ligand(TRAIL),a member of the TNF family,has been shown to be involved in apoptosis during many diseases.As one member of a death ligand family,TRAIL was originally thought to target only tumor cells and was not present in CNS.However,recent data showed that TRAIL was unregulated in HIV-1-infected and immune-activated macrophages,a major disease inducing cell during HIV-1-assoeiated dementia(HAD).TRAIL is also induced on neuron by β-amyloid protein,an important pathogen for Alzheimer's disease.In this review,we summarize the possible common aspects that TRAIL involved those neurodegenerative diseases,TRAIL induced apoptosis signaling in the CNS cells,and specific role of TRAIL in individual diseases.Cellular & Molecular Immunology.2005;2(2):113-122.