Nonreciprocal Metasurface with Space-Time Phase Modulation

Creating materials with time-variant properties is critical for breaking reciprocity that imposes fundamental limitations to wave propagation. However, it is challenging to realize efficient and ultrafast temporal modulation in a photonic system. Here, leveraging both spatial and temporal phase manipulation offered by an ultrathin nonlinear metasurface, we experimentally demonstrated nonreciprocal light reflection at wavelengths around 860 nm. The metasurface, with traveling-wave modulation upon nonlinear Kerr building blocks, creates spatial phase gradient and multi-terahertz temporal phase wobbling, which leads to unidirectional photonic transitions in both momentum and energy spaces. We observed completely asymmetric reflections in forward and backward light propagations within a sub-wavelength interaction length of 150 nm. Our approach pointed out a potential means for creating miniaturized and integratable nonreciprocal optical components.Comment: 25 pages, 5 figure

Molding Free-Space Light with Guided-Wave-Driven Metasurfaces

Metasurfaces with unparalleled controllability of light have shown great potential to revolutionize conventional optics. However, they mainly work with free-space light input, which makes it difficult for full on-chip integration. On the other hand, integrated photonics enables densely packed devices but has limited free-space light controllability. Here, we show that judiciously designed guided-wave-driven metasurfaces can mold guided waves into arbitrary free-space modes to achieve complex free-space functions, such as beam steering and focusing, with ultrasmall footprints and potentially no diffraction loss. Based on the same concept together with broken inversion symmetry induced by metasurfaces, we also realized direct orbital angular momentum (OAM) lasing from a micro-ring resonator. Our study works towards complete control of light across integrated photonics and free-space platforms, and paves new exciting ways for creating multifunctional photonic integrated devices with agile access to free space which could enable a plethora of applications in communications, remote sensing, displays, and etc.Comment: 37 pages, 5 figure

Friend or Foe? The fascinating Tudor-SN protein

Tudor-SN (Tudor staphylococcal nuclease), also known as p100 or SND1 (Staphylococcal nuclease and Tudor domain containing 1), is a structurally conserved protein with diverse functions. Emerging evidence indicates that Tudor-SN plays an essential role in both physiological and pathological processes. Under physiological conditions, Tudor-SN regulates DNA transcription, RNA splicing, RNA stability, RNA interference, and RNA editing, and it is essential for a series of cellular biological events, such as cell cycle progression, cell metabolism, and cell survival, in response to harmful stimuli; thus, Tudor-SN functions as a “friend” to the body. However, Tudor-SN is highly expressed in most tumor cells. As an oncoprotein, Tudor-SN is closely associated with the initiation, development, and metastasis of tumors; thus, Tudor-SN functions as a “foe” to the body. What is the potential mechanism by which Tudor-SN switches from its role as “friend” to its role as “foe”? In this study, we review and summarize the available evidence regarding Tudor-SN protein structure, expression, modification, and mutation to present a novel model of Tudor-SN role switching. This review provides a comprehensive insight into the functional significance of the Tudor-SN protein under physiological and pathological conditions as well as corresponding therapeutic strategies that target Tudor-SN

Integrated Photonics for NASA Applications

No abstract availabl

Friend or Foe? The fascinating Tudor-SN protein

Tudor-SN (Tudor staphylococcal nuclease), also known as p100 or SND1 (Staphylococcal nuclease and Tudor domain containing 1), is a structurally conserved protein with diverse functions. Emerging evidence indicates that Tudor-SN plays an essential role in both physiological and pathological processes. Under physiological conditions, Tudor-SN regulates DNA transcription, RNA splicing, RNA stability, RNA interference, and RNA editing, and it is essential for a series of cellular biological events, such as cell cycle progression, cell metabolism, and cell survival, in response to harmful stimuli; thus, Tudor-SN functions as a “friend” to the body. However, Tudor-SN is highly expressed in most tumor cells. As an oncoprotein, Tudor-SN is closely associated with the initiation, development, and metastasis of tumors; thus, Tudor-SN functions as a “foe” to the body. What is the potential mechanism by which Tudor-SN switches from its role as “friend” to its role as “foe”? In this study, we review and summarize the available evidence regarding Tudor-SN protein structure, expression, modification, and mutation to present a novel model of Tudor-SN role switching. This review provides a comprehensive insight into the functional significance of the Tudor-SN protein under physiological and pathological conditions as well as corresponding therapeutic strategies that target Tudor-SN

Numerical Simulation to Determine the Largest Confining Stress in Longitudinal Tests of Cable Bolts

Bolt support is an economic method of roadway support. However, due to the influence of mining disturbance, the stress of roadway-surrounding rock changes, thus resulting in varying degrees of confining pressure in the radial direction of bolt. In this manuscript, a numerical solution was proposed to determine the largest confining stress in longitudinal tests of cable tendons. FLAC3D was selected to simulate the longitudinal process of cable tendons. The structural pile element was selected to simulate the cable tendon. The loading behavior of the cable was controlled by the cohesive and the frictional behavior of the cable/grout surface. To confirm the credibility of this numerical solution, the loading behavior of a normal cable and an improved cable was simulated. Experimental longitudinal tests were selected to validate the numerical results, showing that there was a satisfactory agreement between numerical and experimental results. The loading behavior of normal cables and improved cables was numerically simulated. Under the same test conditions, when the improved cable was used, the confining medium can generate much higher confining stress compared with normal cable tendons. Consequently, higher confining stress can result in a larger loading capacity of cable tendons

Strata Movement of the Thick Loose Layer under Strip-Filling Mining Method: A Case Study

Filling mining plays an important role in controlling surface subsidence. To study the movement of overburdened rock in filling mining under thick loose layers, a numerical simulation combing field measurement in CT30101 working face in the Mahuangliang coal mine was tested. The results show that different filling rates and filling body strength have different influences on roof and surface movement. The filling rate has a greater impact, which is the main control factor. The filling stress and roof tensile stress decrease gradually with roadway filling. The filling body stress and roof tensile stress in the first and second rounds are far greater than in the fourth round. After the completion of filling, the first and second round of filling bodies mainly bear the overburden, and the total deformation of the surrounding rock of the main transport roadway is very small, and therefore the displacement of the overburdened rock is controllable. The field monitoring results also show that the overburdened rock became stable after several fillings rounds. Combing the numerical modeling and field tests results, this study can be a guideline for similar geological conditions especially for coal mining under thick loose layers and thin bedrock

Strata Movement of the Thick Loose Layer under Strip-Filling Mining Method: A Case Study

Filling mining plays an important role in controlling surface subsidence. To study the movement of overburdened rock in filling mining under thick loose layers, a numerical simulation combing field measurement in CT30101 working face in the Mahuangliang coal mine was tested. The results show that different filling rates and filling body strength have different influences on roof and surface movement. The filling rate has a greater impact, which is the main control factor. The filling stress and roof tensile stress decrease gradually with roadway filling. The filling body stress and roof tensile stress in the first and second rounds are far greater than in the fourth round. After the completion of filling, the first and second round of filling bodies mainly bear the overburden, and the total deformation of the surrounding rock of the main transport roadway is very small, and therefore the displacement of the overburdened rock is controllable. The field monitoring results also show that the overburdened rock became stable after several fillings rounds. Combing the numerical modeling and field tests results, this study can be a guideline for similar geological conditions especially for coal mining under thick loose layers and thin bedrock

Numerical Simulation to Determine the Largest Confining Stress in Longitudinal Tests of Cable Bolts

Bolt support is an economic method of roadway support. However, due to the influence of mining disturbance, the stress of roadway-surrounding rock changes, thus resulting in varying degrees of confining pressure in the radial direction of bolt. In this manuscript, a numerical solution was proposed to determine the largest confining stress in longitudinal tests of cable tendons. FLAC3D was selected to simulate the longitudinal process of cable tendons. The structural pile element was selected to simulate the cable tendon. The loading behavior of the cable was controlled by the cohesive and the frictional behavior of the cable/grout surface. To confirm the credibility of this numerical solution, the loading behavior of a normal cable and an improved cable was simulated. Experimental longitudinal tests were selected to validate the numerical results, showing that there was a satisfactory agreement between numerical and experimental results. The loading behavior of normal cables and improved cables was numerically simulated. Under the same test conditions, when the improved cable was used, the confining medium can generate much higher confining stress compared with normal cable tendons. Consequently, higher confining stress can result in a larger loading capacity of cable tendons