Coupling characteristics of laterally coupled gratings with slots

Laterally-coupled ridge-waveguide distributed feedback lasers fabricated without epitaxial regrowth steps have the advantages of process simplification and low cost.We present a laterally coupled grating with slots.The slots etched between the ridge and grating area are designed to suppress the lateral diffusion of carriers and to reduce the influence of the aspect-ratio-dependent-etching effect on the grating morphology in the etching process.Moreover,the grating height in this structure can be decreased to lower the aspect ratio significantly,which is advantageous over the conventional laterally coupled ridge waveguide gratings.The effects of five main structural parameters on the coupling characteristics of gratings are studied by MODE Solutions.It is found that varying the lateral width of the grating can be used as an effective way to tune the coupling strength;narrow slots(100 nm and 300 nm)and wide ridge(2μm–4μm)promote the stability of grating coupling coefficient and device performance.It is important to note that the grating bottom should be fabricated precisely.The comparative study of carrier distribution and mode field distribution shows that the introduction of narrow slots can strengthen the competitive advantage and stability of the fundamental mode.

All-fiber erbium-doped dissipative soliton laser with multimode interference based on saturable-reserve saturable hybrid optical switch

Reverse saturable absorption is essential for the realization of dissipative solitons.In this paper,we introduce reverse saturable absorption by using nonlinear multimode interference(NL-MMI),for the first time,to the best of our knowledge,and obtain a stable dissipative soliton operation.By adjusting the coupling efficiency from multimode fiber to single mode fiber,the absorption properties of NL-MMI can be switched between saturation and reverse saturation.The dissipative soliton can be obtained with pulse width of 975 fs in the experiment,the 3-dB bandwidth at 1555 nm is 16 nm,and the maximum output power is 11.48 m W.The nonlinear absorption optical modulation and high damage threshold characteristics of the NL-MMI based ultrafast optical switch provide a new idea for realizing dissipative solitons.

Lead-free perovskite Cs_(2)AgBiBr_(6)photodetector detecting NIR light driven by titanium nitride plasmonic hot holes

Lead-free perovskite Cs_(2)AgBiBr_(6)manifests great potential in developing high-performance,environmentally friendly,solution-processable photodetectors(PDs).However,due to the relatively large energy bandgap,the spectrum responses of Cs_(2)AgBiBr_(6)PDs are limited to the ultraviolet and visible region with wavelengths shorter than 560 nm.In this work,a broadband Cs_(2)AgBiBr_(6)PD covering the ultraviolet,visible,and near infrared(NIR)range is demonstrated by incorporating titanium nitride(TiN)nanoparticles that are prepared with the assistance of self-assembled polystyrene sphere array.In addition,an atomically thick Al2O3layer is introduced at the interface between the Cs_(2)AgBiBr_(6)film and TiN nanoparticles to alleviate the dark current deterioration caused by nanoparticle incorporation.As a result,beyond the spectrum range where Cs_(2)AgBiBr_(6)absorbs light,the external quantum efficiency(EQE)of the TiN nanoparticle incorporated Cs_(2)AgBiBr_(6)PD is enhanced significantly compared with that of the control,displaying enhancement factors as high as 2000 over a broadband NIR wavelength range.The demonstrated enhancement in EQE arises from the photocurrent contribution of plasmonic hot holes injected from TiN nanoparticles into Cs_(2)AgBiBr_(6).This work promotes the development of broadband solution-processable perovskite PDs,providing a promising strategy for realizing photodetection in the NIR region.

原子级化学反应促进可弱光探测有机光电倍增探测器的外量子效率超过10^(8)%

外量子效率远大于100%、低成本、溶液法制备的倍增型有机光电探测器(PM-OPDs)引起广泛关注.但该类器件因阳极欧姆接触带来暗电流的恶化,使其弱光探测并不理想.基于此,本文提出了原子级化学反应改善PM-OPDs暗电流及弱光探测策略,进而带来器件综合性能的显著提升.具体地,本文利用原子层沉积技术在空穴传输层PEDOT:PSS与活性层P3HT:PC71BM(100:1)之间引入0.8 nm厚的Al_(2)O_(3)界面层,通过对薄膜拉曼、XPS及FT-IR性能进行表征,发现原子级厚度的Al_(2)O_(3)可与PEDOT:PSS的化学基团发生反应,调节PEDOT:PSS的功函数,进而在阳极一侧形成肖特基接触.通过与阴极肖特基接触协同,器件在保持高倍增行为的同时,暗电流显著降低.最终,器件的弱光探测性能有所改善,相比于标准器件(可探测64 nW/cm^(2)弱光),Al_(2)O_(3)修饰器件可探测低至2.5 nW/cm^(2)的弱光,且相应的外量子效率和响应率分别达到4.31×10^(8)%,1.85×10^(6)A/W,达到目前报道PM-OPDs的最优值.此策略在新型柔性电子产品及医学成像领域具有很好的应用前景.

Tunable aggregation-induced fluorescent and pressure-responsive luminescence supramolecular cages achieved by subcomponent self-assembly

Three discrete tetrahedral metallo-supramolecular cages were designed and constructed using truxenepended base ligands.Owing to the synergistic rigidifying effect of unsymmetric cyano-substituted oligo(pphenylene-vinylene)(u-COPV)suspended by the truxene skeleton,the resulting supramolecular cages were confirmed to exhibit significant aggregation-induced emission(AIE)accompanied by an interesting solvatochromic fluorescent behavior as well as a porous honeycomb-like state during aggregation.In particular,the anti-counterfeiting performance and emission behaviors of the cages in the solid state under external hydrostatic pressure were investigated.

A nanomedicine approach enables co-delivery of cyclosporin A and gefitinib to potentiate the therapeutic efficacy in drug-resistant lung cancer

Drug resistance,accounting for therapeutic failure in the clinic,remains a major challenge to effectively manage cancer.Cyclosporin A(CsA)can reverse multidrug resistance(MDR),especially resistance to epidermal growth factor receptor tyrosine kinase inhibitors.However,the application of both drugs in cancer therapies is hampered by their poor aqueous solubility and low bioavailability due to oral administration.CsA augments the potency of gefitinib(Gef)in both Gef-sensitive and Gef-resistant cell lines.Here,we show that the simultaneous encapsulation of CsA and Gef within polyethylene glycol-block-poly(D,L-lactic acid)(PEG-PLA)produced a stable and systemically injectable nanomedicine,which exhibited a sub-50-nm diameter and spherical structures.Impressively,the co-delivery of therapeutics via single nanoparticles(NPs)outperformed the oral administration of the free drug combination at suppressing tumor growth.Furthermore,in vivo results indicated that CsA formulated in NPs sensitized Gef-resistant cells and Gefresistant tumors to Gef treatment by inactivating the STAT3/Bcl-2 signaling pathway.Collectively,our nanomedicine approach not only provides an alternative administration route for the drugs of choice but also effectively reverses MDR,facilitating the development of effective therapeutic modalities for cancer.

Roles of PFKFB3 in cancer

The understanding of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3(PFK-2/FBPase 3,PFKFB3)has advanced considerably since its initial identification in human macrophages in the mid-1990s.As a vital regulator of glycolysis,accumulating studies have suggested that PFKFB3 is associated with many aspects of cancer,including carcinogenesis,cancer cell proliferation,vessel aggressiveness,drug resistance and tumor microenvironment.In this review,we summarize current knowledge of PFKFB3 regulation by several signal pathways and its function in cancer development in different cell types in cancer tissues.Ubiquitous PFKFB3 has emerged as a potential target for anti-neoplastic therapy.

Domain decomposition based on the spectral element method for frequency-domain computational elastodynamics

We propose a domain decomposition method based on the spectral element method(DDM-SEM)for elastic wave computation in frequency domain.It combines the high accuracy of the spectral element method and the high degree of parallelism of a domain decomposition technique,which makes this method suitable for accurate and efficient simulations of large scale problems in elastodynamics.In the DDM-SEM,the original large-scale problem is divided into a number of well designed subdomains.We use the spectral element method independently for each subdomain,and the neighboring subdomains are connected by a frequency-domain version of Riemann transmission condition(RTC)for elastic waves.For the proposed method,we can employ the non-conforming meshes and different interpolation orders in different subdomains to maximize the efficiency.By separating the internal and boundary unknowns of each subdomain,an efficient and naturally parallelizable block LDU direct solver is developed to solve the final system matrix.Numerical experiments verify its accuracy and efficiency,and show that the proposed DDM-SEM can be a promising numerical tool for accurately and effectively solving large and multi-scale problems of elastic waves.It is potentially valuable for the frequency domain seismic inversion where multiple source illuminations are required.

Iodine-catalyzed amination of benzothiazoles with KSeCN in water to access primary 2-aminobenzothiazoles

A facile and sustainable approach for the amination of benzothiazoles with KSe CN using iodine as the catalyst in water has been disclosed under transition-metal free conditions. The reaction proceeded smoothly to afford various primary 2-amino benzothiazoles in up to 96% yield. A series of control experiments were performed, suggesting a ring-opening mechanism was involved via a radical process. This protocol provides efficient synthesis of primary 2-aminobenzothiazoles.

精确碳点合成:构建有机和无机化学间的桥梁

As the functional carbon dots (CDs) structures have greatly devoted to the applications of well-established materials based on its highly predictable and directional properties, there is still much room for further enhancement and improvement due to the current limitations, such as well-defined, functionalized CDs synthesis via stepwise skeleton growth strategies under atomically precise level. In addition, revealing the internal structure of carbon dots and their structure–activity relationship is also the kernel linkage of connecting organic and inorganic disciplines.

EFFECT OF SOLARIZATION TO KILL BRADYSIA CELLARUM ON CHINESE CHIVE GROWTH AND SOIL MICROBIAL DIVERSITY

Bradysia cellarum Frey (Diptera: Sciaridae) is an important subterranean pestand is especially damaging to Chinese chive. An effective and moreenvironmentally safe method than pesticides is needed for its control. Theefficacy of B. cellarum control, growth of Chinese chive and soil microbialdiversity were investigated after uae of soil solarization to exterminate thisinsect pest. The results show that on the first day after soil solarization 100%control of B. cellarum was achieved. Growth of Chinese chive was lower insolarized plots than in control plots over the first 10 days after treatment. Chivegrowth in solarized plots increased subsequently to match that in the controlplots. Moreover, the soil microbial community diversity in the treatment groupdecreased initially before gradually recovering. In addition, the abundance ofbeneficial microorganisms in the genus Bacillus and the phyla Proteobacteria,Chloroflexi and Firmicutes increased significantly. Soil solarization is thereforepractical and worthy of promotion in Chinese chive-growing regions.

Recent advances in transition-metal-free C–H functionalization of imidazo[1,2-a]pyridines

Imidazo[1,2-a]pyridines are unique nitrogen-containing organic compounds with wide applications in pharma-ceuticals,natural products,material science and organometallics.Due to their significant biological and synthetic value,the construction of imidazo[1,2-a]pyridine scaffolds has been a highly intriguing research topic,and substantial progress had been made in the past decades.In this review,we aim to summarize the current advances in direct C–H functionalization of imidazo[1,2-a]pyridines under transition-metal-free conditions.For the selected examples,we focused on the design and catalytic cycle mechanism,as well as on representative outcomes and applications.