Modulators for Terahertz Communication: The Current State of the Art.

With the increase of communication frequency, terahertz (THz) communication technology has been an important research field; particularly the terahertz modulator is becoming one of the core devices in THz communication system. The modulation performance of a THz communication system depends on the characterization of THz modulator. THz modulators based on different principles and materials have been studied and developed. However, they are still on the way to practical application due to low modulation speed, narrow bandwidth, and insufficient modulation depth. Therefore, we review the research progress of THz modulator in recent years and evaluate devices critically and comprehensively. We focus on the working principles such as electric, optical, optoelectrical, thermal, magnetic, programmable metamaterials and nonlinear modulation methods for THz wave with semiconductors, metamaterials, and 2D materials (such as graphene, molybdenum disulfide, and tungsten disulfide). Furthermore, we propose a guiding rule to select appropriate materials and modulation methods for specific applications in THz communication.

[Clinical analysis of children with group B streptococcal meningitis in 2013-2017 in a single center].

Objective: To explore the clinical features, the risk factors of mortality and drug resistance of the isolates in patients with group B streptococcus (GBS) meningitis. Methods: A retrospective analysis was performed in 96 children with GBS meningitis (46 males and 50 females) at Beijing Children's Hospital Affiliated to Capital Medical University from January 2013 to October 2017. The clinical characteristics, prognosis and drug resistance were reviewed and analyzed. According to the onset time, the patients were divided into early onset disease (EOD, 0-6 days), late onset disease (LOD, 7-89 days) and very late onset disease (VLOD, 90 days-16 years), the clinical features were compared. According to the results of cranial imaging examination, the patients were divided into two groups: those with neurological complications and those without neurological complications. The influencing factors of neurological complications were analyzed. According to the outcome of 28 days after discharge, patients were divided into death group and survival group. The risk factors of mortality were analyzed by multivariate Logistic regression analysis. Non-numeric variables were analyzed with χ(2) test or Fisher's exact test. Numeric variable between groups were compared with nonparametric test. Results: A total of 96 patients were enrolled, including 18 (19%) EOD, 71 (74%) LOD and 7 (7%) VLOD cases. The median age of EOD cases was 2 days, with a range from 0 to 6 days. The median age of LOD cases was 31 days, with a range from 7 to 81 days. The median age of VLOD cases was 153 days, with a range from 95 to 214 days. Before the onset of the disease, the mother had mastitis in 6 cases and premature rupture of membranes in 6 cases. The common clinical manifestations of patients were fever (95%, 91/96), anorexia (65%, 62/96), seizure (56%, 54/96), and consciousness changes (36%, 35/96). The differences were statistically significant in gender (13/18 vs. 28/71 vs. 5/7, χ(2)=7.705, P=0.024), the number of cases who was admitted to intensive care unit (ICU) (5/18 vs. 31/71 vs. 0, χ(2)=6.065, P=0.042) and peripheral blood leukocyte (12(4, 18)×10(9)/L vs. 6(3, 11)×10(9)/L vs. 13(6, 17)×10(9)/L, H=9.885, P=0.007) in EOD group, LOD group and VLOD group. Cranial imaging was performed in 94 patients, 60 patients (64%) developed neurological complications, including subdural effusion (31/94, 33%), followed by intracranial hemorrhage (26/94, 28%), cerebral softening (19/94, 20%), cerebral atrophy (15/94, 16%), ependinitis (8/94, 9%) and hydrocephalus (4/94, 4%). By univariate χ(2) test analysis, seizure (63% (38/60) vs.41% (14/34), χ(2)=4.310, P=0.038) was a risk factor of neurological complications. Within 28 days after discharge, 88 patients survived and 8 patients died, with a fatality rate of 8%. The independent risk factors for the death were septic shock (OR: 9.548, 95% CI 1.439-63.356, P=0.019) and respiratory failure (OR: 7.053, 95% CI 1.160-42.888, P=0.034). All of isolates were susceptible to penicillin (68/68), ceftriaxone (47/47), cefepime (50/50), vancomycin (60/60) and linezolid (54/54), while the rates of resistance to tetracycline, levofloxacin, clindamycin and erythromycin were 5/12, 17/45, 38/46 and 32/37, respectively. Conclusions: The main type of GBS meningitis is late onset cases. The incidence of neurological complications was high. The independent risk factors for death were septic shock and respiratory failure. The strains were severely resistant to clindamycin and erythromycin.

Study of pharmacokinetics of an in situ forming gel system for controlled delivery of florfenicol in pigs.

To reduce florfenicol (FFC) administration frequency in veterinary use, the drug was currently developed into in situ forming gel. Twelve pigs were randomly divided into two groups (six pigs per group). A single i.m. dose of 40 mg/kg body weight (b.w.) was given to pigs, group one was given FFC in situ forming gel, and group two was given FFC conventional injection. High-performance liquid chromatography (HPLC) was used to determine FFC plasma concentrations. There were significant differences (P < 0.01) between FFC in situ forming gel and conventional injection, in pharmacokinetic parameters MRT (mean retention time) (57.79 ± 2.88) h versus (15.94 ± 1.29) h, AUC (area under the concentration-time curve) (421.54 ± 8.97) µg·h/mL versus (168.16 ± 4.59) µg·h/mL, tmax (time of occurrence of cmax ) (9.00 ± 2.68) h versus (4.33 ± 0.82) h, cmax (maximum plasma concentration) (6.87 ± 0.66) µg/mL versus (12.01 ± 0.66) µg/mL, t1/2λz (terminal elimination half-life) (38.04 ± 2.20) h versus (9.15 ± 2.71) h. The results demonstrated that the in situ forming gel system could shorten dosing interval of FFC and thus achieved less frequent administration during long-term treatment.

In vitro and in vivo evaluation of an in situ forming gel system for sustained delivery of Florfenicol.

The objective of this study was to develop an injectable in situ forming gel system based on Poloxamer for sustained release of Florfenicol (FFC). The formulations were prepared containing certain amounts of Poloxamer 407 (P407) and Poloxamer 188 (P188) alone or with hydroxylpropyl methylcellulose (HPMC), sodium carboxymethyl cellulose (CMC-Na), or polyvinyl pyrrolidone (PVP) as polymer additives. The optimal formulation was chosen according to in vitro parameters (gelation temperature, gelation time, pH value, viscosity, and in vitro release). Then the FFC in vivo pharmacokinetic character of the optimal formulation was investigated in dogs with a single dose of 50 mg/kg b.w. under s.c. injection. In vitro release studies, all formulations containing polymer additives had prolonged release time and decreased initial burst to some extent. The optimal formulation containing 0.15% HPMC showed a best sustained release profile for about 128 h with the lowest initial burst in vitro (<40% in 24 h). In vivo, the 20% FFC in situ forming gel provided prolonged drug release time within the therapeutic range for about 100 h, with stable plasma levels and elimination half-life (t1/2λz ) nine times higher than the control formulation. In conclusion, in situ forming gel is an attractive alternative for FFC sustained release system.

[Synthesis and electrochemical behavior of new symmetrical porphyrin and cobalt(II) complex].

The synthesis and characterization of mercapto-porphyrin and its cobalt(II) complex are reported. A new method was used to synthesize the porphyrin. These compounds have not been reported previously. Their structural assignment of the porphyrin and its cobalt(II) complex were based on the elemental analysis, UV-Vis, IR and 1H NMR spectra. The elemental analysis data for C44H30N4H4 was C, 69.32(69, 44) H, 4.30(4.24) N, 7.35(7.36). The data of UV-Vis spectra indicated that soret and Q bands of the TMTBP displayed a red-shift in comparison with TPP. The IR spectra of TMTBP showed that the peak of delta (N-H) disappeared, when the cobalt(II) complex was formed. The 1H NMR spectra proved that a new mercapto-porphyrin has been synthesized. This paper also reported electrochemical behavior of new compounds in DMSO by cyclic voltammetry and differential pulse voltammetry.