Spectrum Allocation and Performance Analysis for Backhauling of UAV Assisted Cellular Network

To reinforce the coverage and QoS(quality of service) of on-ground cellular communication system, unmanned aerial vehicles which are carrying small cells are deployed in some emergency and disaster areas. Although ASCs(aerial small cells) can provide a higher probability of LoS(line-of-sight) transmission, the wireless backhaul link will bring extra interference to the whole system if not well designed. Therefore, in this paper, we study the backhaul scheme for UAV-assist cellular network. We first analyze the interference environments of UAV-assist cellular network considering the IBOG(In-Band to On-Ground), OBOG(Out-of-Band to On-Ground) and IBTU(In-Band to Tethered-UAV) backhauling mode, and give the descriptions of the performance metrics for each mode. Then, the considered problem is formulated as an optimization of achievable rate. We derive the optimal solutions for the involved three backhauling modes for ASCs respectively, and closed-form optimal value for each mode is acquired with proof. We also give a pseudo-code form of our proposed optimal access/backhaul spectrum allocation algorithm. The simulation results indicate that the proposed scheme can deliver a significant gain, while IBTU performs best among proposed backhauling modes.

Molecular Identification of Salvia miltiorrhiza Bge. and Its Adulterants Based on ITS2 Sequences

[ Objectives] The study was conducted to investigate the molecular identification of Salvia miltiorrhiza Bge. and its adulterants by DNA barcoding andspecific primer PCR. [ Methods] With ITS2 sequenceas DNA barcode, the materials were amplified by PCR and sequenced, and the NJ phylogenetic tree was constructed. The secondary structure of ITS2 was predicted by database and its website established by Koetschan et al. , and the self-designed primers were used to carry out specific primer PCR identification. [Results] ITS2 sequence length was around 470 bp. The results of cluster analysis showed that S. miltiorrhiza Bge. and its adulterants were clustered on different branches and showed monophyly. The comparison of secondary structure showed that S. miltiorrhiza Bge. had little differences from S. przewalskii, while there were significant differences from A. lappa in the number, size and location of stem-loop and the rotation angle of the spiral arm from the central ring. The specific primers could distinguish the S. miltiorrhiza Bge. and its counterfeits by PCR technique. [Conclusions] DNA barcoding and specific primer PCR are effective in distinguishing S. miltiorrhiza Bge. and its adulterants, and it has an important application foreground in the identification of Chinese herbal medicines.

A Topology-Matching Spike Protein-Capping Tetrahedral DNA Nanocrown for SARS-CoV-2 Neutralization

The constantly mutating severe acute respiratory syndrome coronavirus-2(SARS-CoV-2)poses great risk of efficacy loss to the present neutralizing therapeutics.Thus,it is urgently needed to develop versatile strategies that enable rapid design and engineering of potent neutralizing therapeutics for newly emerging variants.Herein,we present an unprecedented DNA nanocrown that can topologically match and multivalently bind the S-trimer of SARS-CoV-2 and thereby inhibit its infection to host cells.A neutralizing aptamer binding the N-terminal domain(NTD)supersite of the S protein was first screened and identified.It was further elaborately engineered onto the best fitting tetrahedral DNA nanostructure to form a spike protein-capping nanocrown,which can effectively block not only wild-type(WT)SARS-CoV-2 pseudovirus,but also several important mutants including D614G,N501Y,andΔ69–70.Significantly,it can evidently diminish the RNA copies of authentic WT SARS-CoV-2 in host cells by 4.6 orders of magnitude.Therefore,utilizing the aptamer selection method and the dedicated engineering route,our topology-matching DNA framework provides a versatile platform for SARS-CoV-2 inhibition and has the potential to be facilely expanded to newly emerging variants and other fatal coronaviruses.

High Mannose-Specific Aptamers for Broad-Spectrum Virus Inhibition and Cancer Targeting

High mannose oligosaccharides are characteristic and essential for immune evasion of many viruses and cancer cells.They are potential targets for viral inhibition and cancer diagnosis/therapy.Particularly,high mannose-binding reagents may be a unique asset for fighting the ongoing and mutating SARSCoV-2 virus.Lectins are prevailing reagents for saccharide binding but suffer from inadequate specificity and apparent immunogenicity.Meanwhile,other reagents for the same purpose,such as antibodies and aptamers,have rarely been reported.Herein,using molecularly imprinted magnetic nanoparticles as a potent platform,we report a smart selection method for fine screening of high mannose-specific aptamers.Monovalent aptamers were first effectively screened within eight rounds of selection.Multivalent aptamers,in the forms of dendritic polymer or tetrahedral DNA nanostructure(TDN),were further engineered.The aptamers exhibited high affinity toward the spike protein of SARS-CoV-2 and the envelope protein GP120 of HIV.Both the monovalent aptamer and its TDN form exhibited a certain inhibition effect to the SARS-CoV-2 pseudovirus.On the other hand,both the monovalent aptamer and its dendritic form permitted the recognition of cancer cells over normal cells.Therefore,as unprecedented reagents for broad-spectrum viral inhibition and cancer targeting,these aptamers hold great promise for clinical treatment and diagnosis.