An Investigation of the Effect of Chitosan on Isothermal Crystallization, Thermal Decomposition, and Melt Index of Biodegradable Poly(L-lactic acid)

Biodegradable chitosan (CS) was introduced into another biodegradable poly(L-lactic acid) (PLLA) to prepare the PLLA/CS composites, and the effect of CS on thermal behavior and melt index of PLLA was investigated using modern testing technologies including optical depolarizer, thermogravimetric analysis instrument, and melt index instrument. The relevant testing results showed that both crystallization temperature and CS concentration affected the isothermal crystallization behavior of PLLA. Compared to neat PLLA, the t1/2 of PLLA/5% CS decreased from 2991.54 s to the minimum value 208.76 s at 105°C. However, the t1/2 of PLLA/CS composites in high crystallization temperature zone was different from that in low crystallization temperature zone. The increase of CS concentration and heating rate made the thermal decomposition temperature of PLLA/CS composites shift to higher temperature. The melt index results indicated that 3% CS made the fluidity of PLLA become better

Growth of Wide Band Gap II-VI Compound Semiconductors by Physical Vapor Transport

The studies on the crystal growth and characterization of II-VI wide band gap compound semiconductors, such as ZnTe, CdS, ZnSe and ZnS, have been conducted over the past three decades. The research was not quite as extensive as that on Si, III-V, or even narrow band gap II-VI semiconductors because of the high melting temperatures as well as the specialized applications associated with these wide band gap semiconductors. In the past several years, major advances in the thin film technology such as Molecular Beam Epitaxy (MBE) and Metal Organic Chemical Vapor Deposition (MOCVD) have demonstrated the applications of these materials for the important devices such as light-emitting diode, laser and ultraviolet detectors and the tunability of energy band gap by employing ternary or even quaternary systems of these compounds. At the same time, the development in the crystal growth of bulk materials has not advanced far enough to provide low price, high quality substrates needed for the thin film growth technology

A new impedance matching method for an ultra-wide band and dual circularly polarised feed

In traditional antenna design, metal components are not placed in the central part of the antenna as they change the characteristics of near field radiation. However, we show that placing a metal ring in the centre of the strip lines, which connect the ends of folded high-frequency dipoles, does not damage the performance of the feed. Instead it significantly improves the voltage standing wave ratio of the feed whilst other performance indicators are not compromised. Thus, our findings show an excellent way of improving the wide band feed. Based on this foundation, a new circularly polarised feed for operation between 0.4 to 2 GHz is introduced for the Chinese Spectral Radioheliograph in this paper. The issue of a feed impedance matching network is investigated. By optimising the impedance matching, the performance of the feed is enhanced with respect to the previous realisations of the Eleven feed. The simulation and experimental results show that the gain of the feed is about 10 dBi, and the VSWR is less than 2:1. In addition, the feed has a low axial ratio, fixed phase centre location, and constant beam width in the range of 0.4 to 2 GHz

SHEARING BEHAVIOR OF STRUCTURAL INSULATED PANEL WALL SHELLED WITH BAMBOO SCRIMBER

In this study, shearing behavior of a structural insulated panel (SIP) wall, which consisted of a Styrofoam core board, shell panel of bamboo scrimber, and frame of Spruce–Pine–Fir dimension lumber, was tested under monotonic and cyclic loads. Results showed that the SIP wall failed at similar positions under two loading modes, although more serious destruction occurred under cyclic than monotonic load. There was a linear relationship between load and displacement at the initial loading stage, which indicated that the wall worked under the elastic state. At a later loading stage, bearing capacity and rigidity decreased as a result of wall slip. Shearing strength under monotonic and cyclic loads was 20.0 and 15.8 kNm-1, respectively, which met the requirement of the standard code for design of timber structures. Energy consumption of the SIP wall covered with bamboo scrimber was 11,556.6 Jm-1

Efficacy and safety of latanoprost versus timolol for primary open angle glaucoma and ocular hypertension: a Meta-analysis

AIM: To evaluate the efficacy and safety of latanoprost versus timolol for primary open angle glaucoma(POAG)and ocular hypertension(OHT).<p>METHODS: This was an evidence-based medicine science study. Pertinent studies of randomized controlled trial(RCT)were identified through searches of PubMed, Medline, CNKI and China Biology Medicine disc. The intensive searching by hand and internet was also designed. According to inclusion and exclusion criteria, the study object was limited. Quality of literatures were evaluated by experienced researchers according to the Jadad Score. RevMan 5.0 offered by Cochrane was used for Meta-analysis aimed at the ratio of low intraocular tension and adverse drug reaction.<p>RESULTS: A total of 9 RCT sadded up to 555 patients were involved. The results of meta-analysis showed that, a)the difference at 2, 6, 12wk both had statistical significance, latanoprost showed greater intraocular pressure(IOP)lowering efficacy compared with timolol. The weighted mean difference(WMD)at 2, 6, 12wk was respectively \〖-0.76, 95% <i>CI</i>(-1.32 to -0.20)\〗, \〖-1.15, 95% <i>CI</i>(-1.68 to 0.63)\〗 and \〖-1.01, 95% <i>CI</i>(-1.42 to -0.61)\〗. b)The difference in conjunctival congestion(<i>OR</i>=2.25, 95% <i>CI</i> 0.99 to 5.08)and foreign body sensation(<i>OR</i>=2.48, 95% <i>CI</i> 1.02 to 6.03 )between latanoprost and timolol group was not statistically significant. <p>CONCLUSION: Latanoprost showed greater IOP lowering efficacy at 12wk compared with timolol for OAG and OH patients. The conjunctival hyperemia, foreign body sensation, iris pigmentation deepened, vision damage of latanoprost group at 12wk compared with timolol, the difference was not significant. This conclusion is not powerful enough in proof due to the medium methodology quality of the included studies, so a large number of high-quality RCTs with large sample are needed for objectively, precisely and entirely evaluating the efficacy

Background differences of parental attributes: a case study of a preschool road safety education programme in Perak

This study was carried out to envisage and examine the plausible relationships of parental road safety knowledge, attitude and practice in relation to preschool children’s involvements in a road safety education programme in Perak, Malaysia. Three local preschools were selected for this purpose, in which the children underwent and an educational road safety programme. The respondents consisted of 100 parents of the pre-schoolers (note that two private and one government preschools were chosen through a purposive sampling method). Ethnicity was found to be significantly different compared to knowledge (χ2 = 16.272, p ≤ 0.05) and practice (χ2 = 10.635, p ≤ 0.05) scores. Chi-square analyses indicated that there is an association between parental road safety attitude and practice scores (χ2 = 21.444, p ≤ 0.05). In addition, the study also revealed that the attitude score varied significantly between the parents, while no significant difference was found between gender in knowledge and practice scores. However, this study also postulated that parental attitude and practice on road safety are moderately related to each other. Furthermore, the findings of the analyses also revealed certain gender inequalities, as the study indicated that female parents might have poorer knowledge and attitude scores. However, they appeared to be capable of showing more care and concern over road safety in relation to their preschool children’s safety and well being. Thus, it is hypothesized that road safety education ought to be inculcated among parents, together with their children, vis’ a vis’ to the current campaign on road safety education among young children