Ultra-compact Spatial Terahertz Switch Based on Graphene Plasmonic-Coupled Waveguide

We are proposing graphene (G)-based multilayered plasmonic spatial switch, operating at 10 THz. It is composed of hBN/Ag/hBN/G/hBN/G/hBN/SiO₂/p⁺-Si multilayers. When a 10-THz transverse magnetic (TM)-polarized signal is normally incident upon the structure top surface, the nanoaperture devised in the Ag nanolayer, acting as a grating, excites surface plasmons at the top graphene micro-ribbons/hBN interface. These surface plasmons depending on the graphenes chemical potentials can be coupled to the lower-right or left graphene micro-ribbons and continue to propagate laterally towards the corresponding output port. Numerical simulations show that a change of ∆V_G ≈ ± 2.7 V in the voltage, applied to the gated micro-ribbons, can modulate their chemical potentials sufficiently to switch the right (left) output port from ON (OFF) to OFF(ON) and vice versa. Besides its low power consumption, the switch ultra-small dimensions make it a potential spatial router suitable for THz-integrated circuit applications.

     

Longitudinal roentgencephalometric study of the growth of the New Zealand white rabbit: cumulative and biweekly incremental growth rates for skull and mandible

A longitudinal roentgencephalometric study of the New Zealand white rabbit has documented postnatal skull and mandible growth from 2 to 34 weeks of age. Dorsoventral and lateral radiographs were performed using a specially constructed restrainer that allowed for standardized films and did not require the use of anesthesia. Assessments from 17 male and 12 female rabbits at biweekly intervals documented cumulative growth as well as biweekly incremental growth. Indices reported here include skull length, interzygomatic width, intercondylar width, and mandibular length. Mean skull length at 2 weeks was 54% of that at 34 weeks, and by 16 weeks 91% of adult skull length was achieved. Mean interzygomatic width at 2 weeks was 60% of that at 34 weeks, and by 16 weeks 91% of adult male and 94% of adult female widths were achieved. Mean mandibular length at 2 weeks was 47% of that at 34 weeks, and by age 16 weeks 90% of adult length was achieved. Mean intercondylar width at 2 weeks was 57% of that at 34 weeks, and by 16 weeks 89% of adult male and 93% of adult female widths were achieved. Biweekly increments decreased continually from 2 weeks of age on for all indices.     

High transmission of paternal plastid DNA in alfalfa plants demonstrated by restriction fragment polymorphic analysis

Summary A high frequency of paternal plastid transmission occurred in progeny from crosses among normal green alfalfa plants. Plastid transmission was analyzed by hybridization of radiolabeled alfalfa plastid DNA (cpDNA) probes to Southern blots of restriction digests of the progeny DNA. Each probe revealed a specific polymorphism differentiating the parental plastid genomes. Of 212 progeny, 34 were heteroplastidic, with their cpDNAs ranging from predominantly paternal to predominantly maternal. Regrowth of shoots from heteroplasmic plants following removal of top growth revealed the persistence of mixed plastids in a given plant. However, different shoots within a green heteroplasmic plant exhibited paternal, maternal, or mixed cpDNAs. Evidence of maternal nuclear genomic influence on the frequency of paternal plastid transmission was observed in some reciprocal crosses. A few tetraploid F₁ progeny were obtained from tetraploid (2n=4x=32) Medicago sativa ssp. sativa x diploid (2n=2x=16) M. sativa ssp. falcata crosses, and resulted from unreduced gametes. Here more than the maternal genome alone apparently functioned in controlling plastid transmission. Considering all crosses, only 5 of 212 progeny cpDNAs lacked evidence of a definitive paternal plastid fragment.Contribution No. 89-524-J from the Kansas Agricultural Experiment Station, Kansas State University, Manhattan     

Cation specificity and modes of the Na+:CO3(2-):HCO3- cotransporter in renal basolateral membrane vesicles

The cation specificity and possible exchange modes of the Na+:CO3(2-):HCO3- cotransporter were evaluated by use of basolateral membrane vesicles isolated from rabbit renal cortex. External Li+ inhibited HCO3- gradient-stimulated 22Na uptake, indicating that Li+ interacts with the Na+:CO3(2-):HCO3- cotransporter. No interaction with K+, choline, Rb+, Cs+, or NH4+ could be similarly detected. Imposing an outward Li+ gradient caused quenching of acridine orange fluorescence in the presence but not in the absence of HCO3-, suggesting that Li+:base cotransport takes place via the Na+:CO3(2-):HCO3- cotransporter. Imposing an outward gradient of unlabeled Na+ stimulated the initial rate of 22Na uptake and induced its transient uphill accumulation, indicating Na(+)-Na+ exchange. Na(+)-Na+ exchange was observed in the presence but not in the absence of HCO3- and was inhibited by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), suggesting that it occurs via the Na+:CO3(2-):HCO3- cotransporter. Similarly, an outward Li+ gradient stimulated uphill 22Na accumulation, indicating Na(+)-Li+ exchange. Na(+)-Li+ exchange was observed in the presence but not in the absence of HCO3-, and was inhibited by DIDS, suggesting that it also occurs via the Na+:CO3(2-):HCO3- cotransporter. Both Na(+)-Na+ and Li(+)-Na+ exchange modes were sensitive to inhibition by harmaline but not by amiloride. We conclude that Li+ is an alternative substrate for the renal Na+:CO3(2-):HCO3- cotransporter. Transport modes of the system include cation:base cotransport and HCO3-dependent cation-cation exchange.     

NK cells: An attractive candidate for cancer therapy

Natural killer (NK) cells have significant capability in tumor immune-surveillance. The ability of lyse transformed cells immediately in an antigen-independent manner make them an attractive candidate for cancer cell therapy. Despite employment of NK cells in cancer immunotherapy, clinical trials are faced with serious limitations such as trouble with the penetration of NK cells in tumor sites, limited in vivo persistence, and tumor microenvironment interference. Taken together, the NK-cell cancer therapy is still infant scenario that has a long way to be translated in clinic. Current article first reviews characteristic features of NK lymphocytes. Then, it discusses about important disruptive barriers and motivator in the developmental stages of NK cells like as tumor microenvironment. Finally, some revolutionary approaches are highlighted utilizing of NK cells in cancer therapy.     

Molecular characterization of Plasmodium vivax clinical isolates in Pakistan and Iran using pvmsp-1, pvmsp-3α and pvcsp genes as molecular markers

In this study, the diversity of Plasmodium vivax populations circulating in Pakistan and Iran has been investigated by using circumsporozoite protein (csp) and merozoite surface proteins 1 and 3α (msp-1 and msp-3α) genes as genetic markers. Infected P. vivax blood samples were collected from Pakistan (n = 187) and Iran (n = 150) during April to October 2008, and were analyzed using nested-PCR/RFLP and sequencing methods. Genotyping pvmsp-1 (variable block 5) revealed the presence of type 1, type 2 and recombinant type 3 allelic variants, with type 1 predominant, in both study areas. The sequence analysis of 33 P. vivax isolates from Pakistan and 30 from Iran identified 16 distinct alleles each, with one allele (R-8) from Iran which was not reported previously. Genotyping pvcsp gene also showed that VK210 type is predominant in both countries. Moreover, based on the size of amplified fragment of pvmsp-3α, three major types: type A (1800 bp), type B (1500 bp) and type C (1200 bp), were distinguished among the examined isolates that type A was predominant among Pakistani (72.7%) and Iranian (77.3%) parasites. PCR/RFLP products of pvmsp-3α with HhaI and AluI have detected 40 and 39 distinct variants among Pakistani and Iranian examined isolates, respectively. Based on these three studied genes, the rate of combined multiple genotypes were 30% and 24.6% for Pakistani and Iranian P. vivax isolates, respectively. These results indicate an extensive diversity in the P. vivax populations in both studies.