Comparative In Vitro Osteoinductivity Study of HA and α‐TCP/HA Bicalcium Phosphate

A bicalcium phosphate (BCP) bioceramic comprising α‐tricalcium phosphate (α‐TCP) and hydroxyapatite (HA) was prepared by a two‐step sintering. The microstructure of the BCP bioceramic was investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X‐ray diffraction. The in vitro osteoinductivity was evaluated by culturing MG63 osteoblast‐like cells on the BCP bioceramic. Results showed that the BCP bioceramic comprising α‐TCP and HA in a moderate ratio possessed a hardness of 93.7 Hv. The cells spread faster on the BCP bioceramic than those on the commercial HA. It suggested that the BCP bioceramic can enhance osteoinductivity in vivo.     

220t/h锅炉燃烧器改造

采用波纹钝体燃烧器代替船体燃烧器并将各次风下移等手段对广州发电厂 2 2 0t/h锅炉燃烧器进行改造 ,成功地消除了锅炉燃烧器喷口经常烧坏的故障 ,使锅炉各参数达到了设计要求。图 3表 3参 2     

Design of Liveness-Enforcing Supervisors for Flexible Manufacturing Systems Using Petri Nets

This correspondence develops a methodology to synthesize supervisors for a special class of Petri nets that can well model many flexible manufacturing systems. In our previous work, siphons in a Petri net are divided into elementary and dependent ones on the condition that all emptiable minimal siphons are computed. In this research, a mixed integer programming (MlP)-based deadlock detection technique is used to find some, in general not all, minimal siphons in a plant model without complete siphon enumeration. For each siphon found, depending on its noncontrollability, a monitor is added such that it is invariant-controlled. Our siphon control method guarantees that no emptiable control-induced siphon is generated due to the addition of the monitors. The siphon control process proceeds iteratively until there is no unmarked siphon in the supervisor of a plant model. Compared with the existing approaches, the novel deadlock prevention policy can usually lead to a structurally simple liveness-enforcing supervisor by adding only a small number of monitors and arcs. More importantly, complete siphon enumeration is avoided. A practical flexible manufacturing system (FMS) example is utilized to illustrate the proposed methods.     

Comparison of E-test with agar dilution methods in testing susceptibility of N. gonorrhoeae to azithromycin

AIMS: To assess the immunoexpression of cyclin D1 and retinoblastoma in a cohort of oesophageal squamous cell carcinoma cases from South Africa to see whether there is a relation between these two proteins. In addition, protein expression was correlated with clinicopathological features. METHODS: Fifty biopsies and 30 oesophagectomy specimens were immunostained with commercially available antibodies to cyclin D1 and retinoblastoma proteins, following microwave antigen retrieval. RESULTS: Twenty three of the 80 cases (29%) showed cyclin D1 protein expression. However, only five cases had > 50% of the tumour cells displaying immunopositivity. Three of the four cases with lymph node spread were cyclin D1 positive in the primary tumour and the metastasis. Fifty three cases were immunoreactive with the antiretinoblastoma antibody; 29 of these cases showing > 50% of cells with immunolabelling. Of the 23 cyclin D1 positive cases, 18 were also retinoblastoma positive. No correlation was observed between cyclin D1 and retinoblastoma protein expression and age, sex, race, or histological grade. CONCLUSIONS: Cyclin D1 is expressed in a minority of cases of oesophageal squamous carcinomas from South Africa. However, three of four cases with lymph node spread were cyclin D1 positive, thus indicating that cyclin D1 positive tumours may have a greater propensity for spread. In addition, 18 of 23 cyclin D1 positive cases also expressed retinoblastoma protein. These findings suggest a possible relation between cyclin D1 and retinoblastoma proteins in a proportion of cases of oesophageal squamous.     

Flavonoids and phenolic acids from Labisia pumila (Kacip Fatimah)

Both total phenolic content (TPC) and total flavonoid content (TFC) of Labisia pumila extracts were determined spectrophotometrically. L. pumila leaves extracted in 60% methanol (MeOH) were fractionated on C18 cartridge and the antioxidant property of each fraction was determined by measuring free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity. The 40% MeOH fraction exhibited the highest scavenging activity. Nine flavonols (quercetin, myricetin and kaempferol), two flavanols (catechin and epigallocatechin) and nine phenolic acids were identified from this active fraction by UPLC–ESI-MS/MS, and confirmed by comparison with the mass spectra of standard aglycones, theoretical fragments generated from MS Fragmenter software, and literature values.     

Wear resistance of composites based on ultrahigh molecular weight polyethylene filled with graphite and molybdenum disulfide microparticles

Tribological characteristics of ultrahigh-molecular-weight polyethylene (UHMWPE)-based compositions with graphite and molybdenum disulfide are studied under conditions of dry friction, boundary lubrication, and abrasive wear. It is shown that, under dry sliding friction, the wear rate of UHMWPE-graphite and UHMWPE-MoS2 polymer compositions is halved as compared to that of pure UHMWP, while their mechanical characteristics change only slightly. Under the conditions of abrasive wear, the wear resistance of these composites increases by 1.3–1.5 times. Concentrations of the fillers, which are optimum for improving the wear resistance, are determined. The supramolecular structure and the topography of worn surfaces of the UHMWPE compositions with various concentrations of the fillers are examined. A comparative analysis of the wear resistance of the composites under conditions of dry friction and lubrication is carried out. Mechanisms of the wear of the UHMWPE-graphite and UHMWPE-MoS₂ polymer compositions under conditions of dry sliding friction and abrasive wear are discussed.     

Seamless handover between unicast and multicast multimedia streams

With the deployment of heterogeneous networks, mobile users are expecting ubiquitous connectivity when using applications. For bandwidth-intensive applications such as Interact Protocol Television （IPTV）, multimedia contents are typical- ly transmitted using a multicast delivery method due to its bandwidth efficiency. However, not all networks support multicasting. Multicasting alone could lead to service disruption when the users move from a multicast-capable network to a non-multicast network. In this paper, we propose a handover scheme called application layer seamless switching （ALSS） to provide smooth real-time multimedia delivery across unicast and multicast networks. ALSS adopts a soft handover to achieve seamless playback during the handover period. A real-time streaming testbed is implemented to investigate the overall handover performance, espe- cially the overlapping period where both network interfaces are receiving audio and video packets. Both the quality of service （QoS） and objective-mapped quality of experience （QoE） metrics are measured. Experimental results show that the overlapping period takes a minimum of 56 and 4 ms for multicast-to-unicast （M2U） and unicast-to-multicast （U2M） handover, respectively. The measured peak signal-to-noise ratio （PSNR） confirms that the frame-by-frame quality of the streamed video during the handover is at least 33 dB, which is categorized as good based on ITU-T recommendations. The estimated mean opinion score （MOS） in terms of video playback smoothness is also at a satisfactory level.     

Effect of ambient conditions on drying of herbs in solar greenhouse dryer with integrated heat pump

An even span solar greenhouse dryer was built and applied to dry Java tea (Orthosiphon aristatus) and Sabah snake grass (Clinacanthus nutans Lindau). Findings showed that the solar greenhouse dryer performs satisfactorily during clear weather except at nighttime and rainy day due to product rehydration which is heavily influenced by high relative humidity from ambient air. Integrating of heat pump into the solar greenhouse dryer has successfully reduced the room relative humidity by 10–15%. Also, heat pump has mitigated the product rehydration issue by maintaining room relative humidity at maximum of 65% throughout the drying period. The drying rate of Java tea was improved three to fourfold, i.e., from 0.004–0.008 to 0.018–0.025?g H₂O/g DM min, whereas 10% of drying time was saved for both Java tea leaf and Sabah snake grass leaf with the assistance of heat pump system. Meanwhile, the supply of dry air from the heat pump system with a magnitude of 0.25–0.50?m/s helps in enhancing the drying rate of the herbs as well as minimizing the nonuniformity of drying temperature and relative humidity inside the solar greenhouse dryer.     

内蒙古大青山煤矸石资源化综合利用探讨

综述了煤矸石的产生、分类、性质和危害性,结合目前国内外煤矸石的利用途径,对大青山内蒙古包头石拐矿区煤矸石,从环境可优化、资源可持续、能源可创新、经济可益效等产业链角度出发,提出一系列可行性方案。