Random lasing in micron-sized individual supraparticles.

Self-assembled fluorescent particles have shown promise as a potential structure for random lasers. However, obtaining micron-sized random lasers made with fluorescent particles remains a challenge. Theoretically, achieving micron-sized random lasers could be possible by assembling supraparticles composed of colloidal particles. Despite extensive research on supraparticles, the generation of random lasers from this structure is rarely reported. In this study, we introduce a rapid and efficient method for producing supraparticles from fluorescent particles. The resulting supraparticles exhibit diameters ranging from 50 to 150 µm with particles well-connected and uniformly distributed throughout their structure. Under optical excitation, supraparticles with a diameter larger than 80 µm demonstrate lasing emission with a threshold of approximately 77 µJ·mm-2. Larger supraparticles exhibit a distinct redshift in lasing wavelength compared to the smaller ones. Specifically, the central peak lasing wavelength shows a shift of about 7.5 nm as the supraparticle diameter increases from 80 to 150 µm.

Monodisperse and size-tunable high-quality factor microsphere biolasers.

Microsphere biolasers have attracted a great deal of interest due to their potential for biosensing and cell tracking. Here we demonstrate a novel, to the best of our knowledge, microfluidic-based fabrication of nearly monodisperse dye-doped protein microsphere biolasers with a tunable size from 150 to 50 µm. In particular, for an 85 µm-bead, about 70% of the fabricated microspheres have the same size of 85 µm. Under optical pumping, the fabricated microspheres emit whispering gallery mode lasing emission with a lasing threshold of ${{7}}\;\unicode{x00B5} {\rm{J}}\;{{\rm{mm}}^{- 2}}$ and quality ($\!Q$) factor up to 3000. Interestingly, microspheres with the same size exhibit a similar lasing threshold and spectrum. The result indicates a high reproducibility of microsphere biolasers by the microfluidic-based fabrication technique. This Letter provides an effective method for mass production of high-$Q$ factor microsphere biolasers which is a significant step toward real biosensing and medical applications.

A study of the aphrodisiac properties of Cordyceps militaris in streptozotocin-induced diabetic male rats.

BACKGROUND AND AIM: Cordyceps militaris (CM) is a fungus that has been used to enhance aphrodisiac activity in men, but to date, no studies have focused on its antidiabetic properties. This study aimed to investigate the effects of CM on reproductive performance of streptozotocin (STZ)-induced diabetic male rats. MATERIALS AND METHODS: Six-week-old Wistar rats were randomly divided into four groups: control Group 1 consisting of healthy rats; Group 2, healthy rats treated with CM (100 mg/kg); Group 3, diabetic untreated rats; and Group 4, diabetic rats treated with CM (100 mg/kg). Rats were orally administered with vehicle or CM for 21 days. The body weight, blood glucose level, food intake, epididymal sperm parameter, sexual behavior, serum testosterone level, and antioxidant parameters were determined. RESULTS: The results indicated that CM treatment in STZ-induced diabetic rats significantly improved the epididymal sperm parameter and serum testosterone level and, in turn, their copulatory behavior. CM treatment in diabetic rats significantly ameliorated malondialdehyde level and significantly improved the glutathione and catalase levels. CONCLUSION: These results provide new information on the pharmacological properties of CM in ameliorating testicular damage due to oxidative stress and improving sexual performance in diabetic male rats.

Exploiting Opportunistic Scheduling Schemes and WPT-Based Multi-Hop Transmissions to Improve Physical Layer Security in Wireless Sensor Networks.

This paper studies the secrecy performance of wireless power transfer (WPT)-based multi-hop transmissions in wireless sensors networks (WSNs), where legitimate nodes harvest energy from multiple power beacons (PBs) to support the multi-hop secure data transmission to a destination in the presence of an eavesdropper. Specifically, the PBs not only transfer radio frequency energy to the legitimate nodes but also act as friendly jammers to protect data transmission. To improve secrecy performance, we propose two secure scheduling schemes, named minimum node selection (MNS) scheme and optimal node selection (ONS) scheme. We then evaluate the performance of the proposed schemes in terms of the exact closed-form for secrecy outage probability (SOP) and asymptotic SOP. The developed analyses are verified by Monte-Carlo simulations. The numerical results show that the ONS scheme outperforms the MNS scheme emerging as an effective protocol for secure multi-hop transmission in WSNs. Furthermore, the effects of the number of PBs, number of hops, time switching ratio, and the secure target data rate on the system performance are also investigated.

Protein-based microsphere biolasers fabricated by dehydration.

Biolasers made of biological materials have attracted considerable research attention due to their biocompatibility and biodegradability, and have the potential for biosensing and biointegration. However, the current fabrication methods of biolasers suffer from several limitations, such as complicated processing, time-consuming and environmentally unfriendly nature. In this study, a novel approach with green processes for fabricating solid-state microsphere biolasers has been demonstrated. By dehydration via a modified Microglassification™ technology, dye-doped bovine serum albumin (BSA) droplets could be quickly (less than 10 minutes) and easily changed into solid microspheres with diameters ranging from 10 µm to 150 µm. The size of the microspheres could be effectively controlled by changing either the concentration of the BSA solution or the diameter of the initial droplets. The fabricated microspheres could act as efficient microlasers under an optical pulse excitation. A lasing threshold of 7.8 µJ mm-2 and a quality (Q) factor of about 1700 to 3100 were obtained. The size dependence of lasing characteristics was investigated, and the results showed a good agreement with whispering gallery mode (WGM) theory. Our findings contribute an effective technique for the fabrication of high-Q factor microlasers that may be potential for applications in biological and chemical sensors.