A New Compact and High Gain Circularly-Polarized Slot Antenna Array for Ku-Band Mobile Satellite TV Reception

© 2013 IEEE. A compact and high-gain SIW-fed circularly polarized (CP) slot-antenna array with a stacked feed structure is presented for the application of Ku-band high-data-rate satellite communications. First, a novel probe-fed SIW cavity with four slots etched on the top surface is proposed as a high-gain radiating element for the array. The four slots in the cavity act as a 2\times2 array, and its directivity is 2.15 and 1.43 dB greater than that of the cavity-backed antenna of the same size using ring slot and split ring slot, respectively. Second, a compact 1-4 SIW power divider is designed for exciting a subarray. Third, the 2\times2 subarray is further expanded to an 8\times16 array by adopting an additional layer of 1-32 SIW feeding network to meet the gain requirement of the Ku-band mobile satellite TV reception. Finally, experiments are carried out to verify the designed prototypes. Measured results show that proposed 128-element array has a relative impedance bandwidth of 4.8% (11.84 to 12.42 GHz), AR bandwidth of 130 MHz (12.01 to 12.14 GHz), and a peak gain of 26.8 dBic at 12.06 GHz. Owing to the simple feeding networks and the compact radiating element, the antenna has a compact size of 6.04\lambda 0 \times 11.96\lambda 0 \times 0.1\lambda 0. Experimental results show that the proposed CP antenna array is suitable for applications of Ku-band mobile satellite TV reception

Association of Plasma Aß Peptides with Blood Pressure in the Elderly

Background Aß peptides are often considered as catabolic by-products of the amyloid ß protein precursor (APP), with unknown physiological functions. However, several biological properties have been tentatively attributed to these peptides, including a role in vasomotion. We assess whether plasma Aß peptide levels might be associated with systolic and diastolic blood pressure values (SBP and DBP, respectively). Methodology/Principal Findings Plasma Aß1-40 and Aß1-42 levels were measured using an xMAP-based assay in 1,972 individuals (none of whom were taking antihypertensive drugs) from 3 independent studies: the French population-based 3C and MONA-LISA (Lille) studies (n = 627 and n = 769, respectively) and the Australian, longitudinal AIBL study (n = 576). In the combined sample, the Aß1-42/ Aß1-40 ratio was significantly and inversely associated with SBP (p = 0.03) and a similar trend was observed for DBP (p = 0.06). Using the median age (69) as a cut-off, the Aß1-42/Aß1-40 ratio was strongly associated with both SBP and DBP in elderly individuals (p = 0.002 and p = 0.03, respectively). Consistently, a high Aß1-42/ Aß1-40 ratio was associated with a lower risk of hypertension in both the combined whole sample (odds ratio [OR], 0.71; 95% confidence interval [CI], 0.56-0.90) and (to an even greater extent) in the elderly subjects (OR, 0.53; 95% CI, 0.37–0.75). Lastly, all these associations appeared to be primarily driven by the level of plasma Aß1-40. Conclusion The plasma Aß1-42/Aß1-40 ratio is inversely associated with SBP, DBP and the risk of hypertension in elderly subjects, suggesting that Aß peptides affect blood pressure in vivo. These results may be particularly relevant in Alzheimer\u27s disease, in which a high Aß1-42/Aß1-40 plasma ratio is reportedly associated with a decreased risk of incident disease

Echinococcus multilocularis and Echinococcus shiquicus in a small mammal community on the eastern Tibetan Plateau : host species composition, molecular prevalence, and epidemiological implications

Background The eastern part of the Tibetan Plateau is now recognized as an endemic region with the highest reported human infection rates in the world of human alveolar echinococcosis (AE) caused by Echinococcus multilocularis. Existing epidemiological studies on AE have mainly focused on the synanthropic environment, while basic parasitological and ecological aspects in wildlife host species remain largely unknown, especially for small mammal hosts. Therefore, we examined small mammal host species composition, occurrence, and the prevalence of both E. multilocularis and E. shiquicus in Shiqu County (Sichuan Province, China), eastern Tibetan Plateau. Results In total, 346 small mammals from five rodent and one pika species were trapped from four randomly set 0.25 ha square plots. Two vole species, Lasiopodomys fuscus (n = 144) and Microtus limnophilus (n = 44), and the plateau pika (Ochotona curzoniae) (n = 135), were the three most-dominant species trapped. Although protoscoleces of E. multilocularis and E. shiquicus were only observed in L. fuscus and O. curzoniae, respectively, cox1 and nad1 gene DNA of E. shiquicus was detected in all the small mammal species except for Neodon irene, whereas E. multilocularis was detected in the three most-dominant species. The overall molecular prevalence of Echinococcus species was 5.8 (95% CI: 3.3–8.2%) ~ 10.7% (95% CI: 7.4–14.0%) (the conservative prevalence to the maximum prevalence with 95% CI in parentheses), whereas for E. multilocularis it was 4.3 (95% CI: 2.2–6.5%) ~ 6.7% (95% CI: 4.0–9.3%), and 1.5 (95% CI: 0.2–2.7%) ~ 4.1% (95% CI: 2.0–6.1%) for E. shiquicus. The prevalence of both E. multilocularis and E. shiquicus, was significantly higher in rodents (mainly voles) than in pikas. Phylogenetic analyses revealed that Echinococcus haplotypes of cox1 from small mammal hosts were actively involved in the sylvatic and anthropogenic transmission cycles of E. multilocularis in the eastern Tibetan Plateau. Conclusions In contrast to previous studies, the current results indicated that rodent species, rather than pikas, are probably more important natural intermediate hosts of E. multilocularis and E. shiquicus in the eastern Tibetan Plateau. Thus, understanding interspecific dynamics between rodents and pikas is essential to studies of the echinococcosis transmission mechanism and human echinococcosis prevention in local communities. Keywords: Echinococcus multilocularis, E. shiquicus, Small mammal Prevalence, Tibetan Platea

A novel injectable chlorhexidine thermosensitive hydrogel for periodontal application: preparation, antibacterial activity and toxicity evaluation

The aim of this paper was to evaluate the application potential of CS-HTCC/GP-0.1%Chx thermosensitive hydrogel which was synthesized using chitosan (CS), quaternized CS, and alpha,beta-glycerophosphate (alpha,beta-GP) loading with 0.1% chlorhexidine (Chx) (w/v) for periodontal treatment. An aqueous solution of CS-HTCC/GP-0.1%Chx was transformed into hydrogel at 6 min when the temperature was increased to 37A degrees C. The scan electron microscopy (SEM) image of the gel was a porous, loose and crosslinked network. In vitro, Chx released over 18 h from the CS-HTCC/GP thermosensitive hydrogel in artificial saliva pH 6.8. Release rate could be controlled through adjustment of alpha,beta-GP or Chx concentration. CS-HTCC/GP-0.1%Chx thermosensitive hydrogel exhibited excellent inhibitory activity against primary periodontal pathogens. CS-HTCC/GP-0.1%Chx thermosensitive hydrogel had no acute toxicity; the maximum tolerated dose in rats was 400 mg/ml. All results indicated that CS-HTCC/GP-0.1%Chx thermosensitive hydrogel is a strong candidate as a local drug delivery system for periodontal treatment

Inhibitory effect of 4-cyanobenzaldehyde and 4-cyanobenzoic acid on mushroom (Agaricus bisporus) tyrosinase

Mushroom tyrosinase (EC 1.14.18.1), a copper containing oxidase, catalyzes both the hydroxylation of tyrosine into o-diphenols and the oxidation of o-diphenols into o-quinones. In the current study, the effects of 4-cyanobenzaldehyde and 4-cyanobenzoic acid on the monophenolase and diphenolase activities of mushroom tyrosinase have been studied. The results show that 4-cyanobenzaldehyde and 4-cyanobenzoic acid can inhibit both the monophenolase activity and the diphenolase activity of mushroom tyrosinase. The lag phase of tyrosine oxidation catalyzed by the enzyme was obviously lengthened, and the steady-state activity of the enzyme decreased sharply. 1.0 mM 4-cyanobenzaldehyde and 4-cyanobenzoic acid can lengthen the lag phase from 78 s to 134 and 115 s, respectively. Both 4-cyanobenzaldehyde and 4-cyanobenzoic acid can lead to reversible inhibition of the enzyme. The IC50 values of 4-cyanobenzaldehyde and 4-cyanobenzoic acid were estimated as 0.62 and 2.45 mM for monophenolase and as 0.72 and 1.40 mM for diphenolase, respectively. A kinetic analysis shows that 4-cyanobenzaldehyde and 4-cyanobenzoic acid are mixed-type inhibitors for the diphenolase. The apparent inhibition constants for 4-cyanobenzaldehyde and 4-cyanobenzoic acid binding with both the free enzyme and the enzyme-substrate complex have been determined and compared

Inhibitory effects of 4-vinylbenzaldehyde and 4-vinylbenzoic acid on the activity of mushroom tyrosinase

Tyrosinase (EC 1.14.18.1) catalyzes both the hydroxylation of ryrosine into o-diphenols and the oxidation of o-diphenols into o-quinones which form brown or black pigments. Here, the inhibitory effects of 4-vinylbenzaldehyde and 4-vinylbenzoic acid on the activity of mushroom tyrosinase have been investigated. The results showed that both 4-vinylbenzaldehyde and 4-vinylbenzoic acid could inhibit both monophenolase activity and diphenolase activity of the enzyme. For the monophenolase activity, 4-vinylbenzoic acid could lengthen the lag time, but 4-vinylbenzaldehyde could not. Both 4-vinylbenzaldehyde and 4-vinylbenzoic acid decreased the steady-state activity, and the IC50 values were estimated as 93 mu M and 3.0 mM for monophenolase activity, respectively. For the diphenolase activity, the inhibitory capacity of 4-vinylbenzaldehyde was stronger than that of 4-vinylbenzoic acid, and the IC50 values were estimated as 23 mu M and 0.33 mM, respectively. Kinetic analyses showed that inhibition by both compounds was reversible and their mechanisms were mixed-II type; their inhibition constants were also determined and compared

Inhibitory effects on mushroom tyrosinase by p-alkoxybenzoic acids

The inhibitory kinetics of the diphenolase of mushroom tyrosinase by seven p-alkoxybenzoic acids has been studied. The results show that these derivatives of benzoic acid behave as reversible inhibitors. Among them, p-hydroxybenzoic acid is competitive, while p-methoxybenzoic acid is non-competitive, p-ethoxybenzoic acid is mixed-II type, and the rest all behave as classical uncompetitive inhibitors. The inhibition constants of all of the seven compounds assayed, characterizing the inhibition, were evaluated. The models of the interactions between the enzyme and the inhibitors are compared. (C) 2004 Elsevier Ltd. All rights reserved

Irreversibly inhibitory kinetics of 3,5-dihydroxyphenyl decanoate on mushroom (Agaricus bisporus) tyrosinase

3,5-Dihydroxyphenyl decanoate (DPD) is found to inhibit the diphenolase activity of tyrosinase from mushroom (Agaricus bisporus). The effects of DPD on the diphenolase activity of mushroom tyrosinase have been studied. The results show that the enzyme activity decreases very slowly with an increase in DPD concentrations at lower concentrations of DPD (between 5 and 60 mu M). But at higher concentrations of DPD, DPD can strongly inhibit the diphenolase activity of the enzyme and the inhibition is irreversible. The IC50 value was estimated to be 96.5 mu M. The inhibition mechanism of DPD has been investigated and the results show that DPD can bind to the free enzyme molecule and enzyme-substrate complex and lose the enzyme activity completely. The inhibition kinetics has been studied in detail by using the kinetic method of the substrate reaction described by Tsou. The microscopic rate constants of the enzyme inhibited by DPD at higher concentrations have been determined. (c) 2005 Elsevier Ltd. All rights reserved

Inhibitory effects of cinnamic acid and its derivatives on the diphenolase activity of mushroom (Agaricus bisporus) tyrosinase

The effects of cinnamic acid and its derivatives (2-hydroxycinnamic acid, 4-hydroxycinnamic acid and 4-methoxycinnamic acid) on the activity of mushroom tyrosinase have been studied. Results showed that cinnamic acid, 4-hydroxycinnamic acid and 4-methoxycinnamic acid strongly inhibited the diphenolase activity of mushroom tyrosinase and the inhibition was reversible. The IC50 values were estimated to be 2.10, 0.50 and 0.42 mM, respectively. 2-Hydroxycinnamic acid had no inhibitory effect on the diphenolase activity of the enzyme. Kinetic analyses showed that the inhibition type of cinnamic acid and 4-methoxycinnamic acid was noncompetitive with the constants (K-I) determined to be 1.994 and 0.458 mM, respectively. The inhibition type of 4-hydroxycinnamic acid was competitive, with the inhibition constant (K-I) was 0.244 mM. © 2004 Elsevier Ltd. All rights reserved