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We introduce a novel type of twisted partially coherent beams with a nonconventional correlation function, named the twisted Hermite-Gaussian correlated Schell-model (THGCSM) beam. The condition that a twist phase can be imposed on a partially coherent beam is addressed for Schell-model fields endowed with rectangular symmetry. Further, the analytical formula for the THGCSM beam propagating in free space has been derived with the help of the generalized Collins formula. The propagation properties, such as the spectral density and the spectral degree of coherence (SDOC) of the THGCSM beam, also have been studied in detail by some numerical examples. The numerical results show that the twist phase plays a role in resisting beam splitting, caused by the correlation structure, and induces the rotation of the distribution of the SDOC on propagation. Moreover, it is interesting to find that when the beam carries a twist phase, this will endow the beam the ability to maintain its distribution of the SDOC on propagation and enhance the self -reconstruction capability of the SDOC. Our results may provide new insights into nonconventional partially coherent beams with twisted phase and may be useful in some applications, such as optical communications and information recovery.

Coherence, similar to amplitude, polarization, and phase, is a fundamental characteristic of the light fields and is dominated by the statistical optical property. Although spatial coherence is one of the pivotal optical dimensions, it has not been significantly manipulated on the photonic platform. Here, we theoretically and experimentally manipulate the spatial coherence of light fields by loading different random phase distributions onto the wavefront with a metasurface. We achieve the generation of partially coherent light with a predefined degree of coherence and continuously modulate it from coherent to incoherent by controlling the phase fluctuation ranges or the beam sizes. This design strategy can be easily extended to manipulate arbitrary phase-only special beams with the same degree of coherence. Our approach provides straightforward rules to manipulate the coherence of light fields in an extra-cavity-based manner and paves the way for further applications in ghost imaging and information transmission in turbulent media.

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Magnesium and magnesium alloys have great application potential in the field of orthopaedics. Compared with traditional inorganic nonmetallic materials and medical polymer materials, magnesium alloys have many advantages, such as better strength, toughness, fatigue resistance, and easy processing. Its mechanical properties are suitable and controllable. It can meet the same elastic modulus, cell compatibility, and biodegradability as human cortical bone. There are also some drawbacks for biodegradability, as magnesium and its alloys, with their high degradation rate, can cause insufficient integrity of the mechanical properties. This paper summarises the research on magnesium and its magnesium alloy materials in the field of bone implantation, looking at what magnesium and its magnesium alloys are, the history of magnesium alloys in bone implant materials, the manufacturing of magnesium alloys, the mechanical properties of magnesium alloys, the bio-compatibility and clinical applications of magnesium alloys, the shortcomings, and the progress of research in recent years.