Double-sided asymmetric metasurfaces achieving sub-microscale focusing from a GaN green laser diode.

We proposed and demonstrated a highly efficient sub-microscale focusing from a GaN green laser diode (LD) integrated with double-sided asymmetric metasurfaces. The metasurfaces consist of two nanostructures in a GaN substrate: nanogratings on one side and a geometric phase based metalens on the other side. When it was integrated on the edge emission facet of a GaN green LD, linearly polarized emission was firstly converted to the circularly polarized state by the nanogratings functioning as a quarter-wave plate, the phase gradient was then controlled by the metalens on the exit side. In the end, the double-sided asymmetric metasurfaces achieve a sub micro-focusing from linearly polarized states. Experimental results show the full width at half maximum of the focused spot size is about 738 nm at the wavelength 520 nm and the focusing efficiency is about 72.8%. Our results lay a foundation for the multi-functional applications in optical tweezers, laser direct writing, visible light communication, and biological chip.

C(sp3 )-H Functionalizations Promoted by the Gold Carbene Generated from Vinylidenecyclopropanes.

The gold carbene generated from vinylidenecyclopropanes (VDCPs) can smoothly perform a C(sp3 )-H bond insertion reaction, stereoselectively affording the intramolecular C(sp3 )-H bond functionalized product, benzoxepine, with syn-configuration in moderate to good yields under mild conditions. The KIE investigation on this bond functionalization partially revealed that the carbene insertion step might be rate-determining. Using a chiral gold(I) catalyst, the first example on the asymmetric variant of gold carbene insertion into C(sp3 )-H bond has been disclosed, giving the desired products with excellent results.

Gold(i)-catalyzed cycloisomerization of vinylidenecyclopropane-enes via carbene or non-carbene processes.

Gold catalyzed cycloisomerization of aromatic ring tethered vinylidenecyclopropane-enes provides a divergent synthetic protocol for the construction of O-containing fused heterocycles through controllable carbene or non-carbene related processes. The carbene induced process features a new amphiphilic strategy to generate a gold carbene via a rearrangement of vinylidenecyclopropane. Whereas, the electronic effect of the ortho-substituents switches the reaction mode onto the non-carbene related process, from which five- or six-membered rings are selectively produced through allyl-migration.

Grignard reagent/CuI/LiCl-mediated stereoselective cascade addition/cyclization of diynes: a novel pathway for the construction of 1-methyleneindene derivatives.

Diynes containing a cyclopropane group smoothly undergo a novel intramolecular and stereoselective cascade addition/cyclization reaction to produce the corresponding 1-methyleneindene derivatives in moderate to good yields. This interesting transformation is mediated by Grignard reagent/CuI with LiCl as an additive under mild conditions. The obtained product can easily be further functionalized through cyclopropyl ring opening. A plausible reaction mechanism has also been presented on the basis of deuterium labeling and control experiments.

[The clinical application and research on vas deferens laser coagulation sterilization].

OBJECTIVE: To study the effect of Ar(+) laser on human vas deferens and to compare the effects of using different radiation levels with varying thickness of tissue and varying levels of injury. METHODS: After initial tests on animals, four human scrotums were opened and treated directly with Ar(+) laser radiation. Then 58 human individual scrotums were treated with radiation by the method of trans-skin puncture. The rate of sperm reduction and elimination was tested. RESULTS: In 60 cases, the sperms were found to be eliminated completely after six months of radiation treatment. In 2 cases the sperms were found not to be eliminated completely due to the insufficient radiation. CONCLUSION: Ar(+) laser is one of the best forms of radiation for coagulation of vas deferens. It can be used to coagulate vas deferens without any complications or sequelae.

The Involvement of Plastoquinone in the Pyocyanine-mediated Cyclic Electron Transport around Photosystem I.

2,5 dibromo-3-methyl-5-isopropyl-p-benzoquinone (DBMIB), an inhibitor of plastoquinone, inhibited photosystem I cyclic electron transport mediated by pyocyanine of low concentration, but had no effect on that mediated by phenazine methosulphate (PMS). In the presence of pyocyanine, the thylakoids displayed a transient post-illumination increase in chlorophyll fluorescence which resembled that displayed in leaves. The above results indicate the involvement of plastoquinone in the pyocyanine-mediated cyclic electron transport around photosystem I.