ABSTRACT
This article presents a dual-wavelength signal wave output system capable of generating a broad range of adjustable wavelength intervals. The setup involved the creation of a dual-wavelength cascaded Raman laser featuring composite cavities operating at 1176â nm and 1313â nm. Experimental investigations were carried out on an external cavity MgO:PPLN-OPO driven by the cascaded Raman laser. By setting the crystal polarization period to 27.6-34.4â µm and the temperature to 50-130°C, adjustable tunable output of dual-wavelength signal wave at 1176â nm-MgO:PPLN-OPO (1550-2294â nm) and 1313â nm-MgO:PPLN-OPO (1768-2189â nm) was achieved with a wavelength interval of 0-218â nm. Under the conditions of a period of 34.4â µm, temperature of 90°C, and an incident Raman power of 2.6 W, the highest conversion efficiency of Raman to dual-wavelength signal wave (2212, 2182â nm) was 34.2%. Furthermore, the maximum output power of dual-wavelength signal wave was recorded at 1.02 W with an incident Raman power of 3.33 W.
ABSTRACT
RNA viruses are often cited as a significant factor affecting the populations of both domestic honey bees and wild pollinators. To expedite the development of effective countermeasures against these viruses, a more comprehensive understanding of virus biology necessitates extensive collaboration among scientists from diverse research fields. While the infectious virus clone is a robust tool for studying virus diseases, the current methods for synthesizing infectious clones of bee-infecting RNA viruses entail the in vitro transcription of the viral genome RNA in 8-10 kb, presenting challenges in reproducibility and distribution. This article reports on the synthesis of an infectious clone of the Chinese variant sacbrood virus (SBV) using a DNA plasmid containing an Autographa californica multiple nucleopolyhedrovirus (AcMNPV) immediate-early protein (IE1) promoter to trigger transcription of the downstream viral genome within hosts. The results demonstrate that the IE1-SBV plasmid can synthesize SBV clones in a widely used lepidopteran immortal cell line (Sf9) and honey bee pupae. Furthermore, the negative strand of the clone was detected in both Sf9 cells and honey bee pupae, indicating active infection and replication. However, the transfection of Sf9 cells was observed in only a limited proportion (less than 10%) of the cells, and the infection did not appear to spread to adjacent cells or form infective virions. The injection of honey bee pupae with 2500 ng of the IE1-SBV plasmid resulted in high infection rates in Apis cerana pupae but low rates in A. mellifera pupae, although the dosage was comparatively high compared with other studies using in vitro transcribed viral RNA. Our findings suggest that the synthesis of bee-infecting RNA viruses using DNA plasmids is feasible, albeit requiring additional optimization. However, this method holds substantial potential for facilitating the production of clones with various sequence modifications, enabling the exploration of viral gene functions and biology. The ease of distributing infectious clones in DNA plasmid form may foster collaboration among scientists in applying the clone to bee biology, ecology, and behavior, ultimately offering a comprehensive approach to managing virus diseases in the future.
ABSTRACT
Viruses are factors that can fluctuate insect populations, including honey bees. Most honey bee infecting viruses are single positive-stranded RNA viruses that may not specifically infect honey bees and can be hazardous to other pollinator insects. In addition, these viruses could synergize with other stressors to worsen the honey bee population decline. To identify the underlying detailed mechanisms, reversed genetic studies with infectious cDNA clones of the viruses are necessary. Moreover, an infectious cDNA clone can be applied to studies as an ideal virus isolate that consists of a single virus species with a uniform genotype. However, only a few infectious cDNA clones have been reported in honey bee studies since the first infectious cDNA clone was published four decades ago. This article discusses steps, rationales, and potential issues in bee-infecting RNA virus cloning. In addition, failed experiences of cloning a Deformed wing virus isolate that was phylogenetically identical to Kakugo virus were addressed. We hope the information provided in this article can facilitate further developments of reverse-genetic studies of bee-infecting viruses to clarify the roles of virus diseases in the current pollinator declines.
ABSTRACT
Active elements play key roles in improving the interfacial bonding between Ag-based fillers and AlN ceramics. An understanding of the influence mechanism of active elements to interfacial adhesion can help us optimize the composition of active filler metals. In this paper, Ag(111)/AlN(0001) interfaces with different terminations and stacking sequences were constructed first. The N-terminated A-site interface was found to have the largest work of adhesion (Wad). Then, the effects of Si, Ti and V dopants on the Ag/AlN interfacial bonding were investigated via first-principles calculations. The results reveal that the Ti and V dopants can increase the values of Wad significantly. Electronic structure analysis reveals that the Si-N, Ti-N and V-N bonds formed at the interface are mainly ionic, and with some composition of covalent. Ti and V atoms can form strong bonds with not only the AlN slab, but also the neighboring Ag layers. It can be concluded that Ag-Ti and Ag-V active fillers are more suited to braze AlN. Ti-N and V-N compounds formed at the interface can greatly improve the interfacial bonding strength.
ABSTRACT
A convenient thermocyclization of the linear gramicidin S precursor and its analogues is demonstrated. With the preorganized ß-sheet conformation, the unactivated linear precursors can cyclize into the corresponding head-to-tail cyclic products in high yield after being heated under solvent-free conditions.
