Different types of MWNTs/epoxy composites were prepared with diglycidyl ether of bisphenol F (DGEBF) and bisphenol A (DGEBA) used as epoxy resins. MWNTs were functionalized to enhance the properties of epoxy composites by treatment with strong acids (acid-treated MWNTs, a-MWNTs) followed by m-phenylenediamine grafting (amine grafted MWNTs, m-MWNTs). Raw, a-, and m-MWNTs were dispersed in DGEBF or DGEBA to a concentration of 1wt.%. X-ray photoelectron spectroscopy and thermogravimetric analysis verified the effectiveness of acid treatment and confirmed the amine-functionalization of the MWNTs. Scanning electron microscopy of the fracture surface of the epoxy matrix showed that chemical functionalization improves compatibility between the epoxy and MWNTs. Good dispersion of MWNTs leads to the improvement in coalescence and pull strength in the quad flat package (QFP) test. Further, the thermal conductivity of MWNTs/epoxy composites was higher than that of pure epoxy resins. In particular, the m-MWNT/epoxy composite has the best heat dissipation properties, due to the formation of an effective network for heat flow.
The mechanical and wetting properties of the diglycidyl ethers of bisphenol A (DGEBA) and bisphenol F (DGEBF) with epoxy-terminated siloxane oligomers (ETSO) were investigated to examine their durabilities as anisotropic conductive adhesive (ACA) resins. The mechanical properties were improved by decreasing the ETSO content due to the high cross-linking density resulting from the short-chain length of ETSO–diaminodiphenylmethane (DDM). To obtain good wettability in both systems, a short-chain reductant (butanoic acid, BA) was added. DGEBF produced enhancement in the wetting angle compared to that of DGEBA due to its low viscosity. DGEBF can be considered an eco-friendly material in this process since it does not require the use of other chemicals, such as a diluent. Therefore, DGEBF/ETSO–DDM with reductant constitutes a suitable system for favorable environmental processing.
This study investigated the effect of the viscosity of the ECAs using a low-melting-point alloy (LMPA) filler on its bonding characteristics. The curing behaviors of the ECAs were determined using Differential Scanning Calorimetry (DSC), and ECA temperature-dependant viscosity characteristics were observed using a torsional parallel rheometer. The wetting test was conducted to investigate the reduction capability of ECAs and the flow-coalescence-wetting behavior of the LMPAs in ECAs. Electrical and mechanical properties were determined and compared to those with commercial ECAs and eutectic tin/lead (Sn/Pb) solder. In the metallurgically interconnected Quad Flat Package (QFP) joint, a typical scallop-type Cu–Sn intermetallic compound (IMC) layer formed at the upper SnBi/Cu interface after curing process. On the other hand, a (Cu, Ni)6Sn5 IMC layer formed on the SnBi/ENIG interface. In addition, the fracture surface exhibited by cleavage fracture mode and the fracture was propagated along the Cu–Sn IMC/SnBi interface. The extremely low-level viscosity of ECAs had a significant influence on the flow-coalescence-wetting behavior of the LMPAs in ECAs and also on the interconnection properties. Stable interconnected assemblies showed good electrical and mechanical properties.
Gas permeabilities and selectivities of some gases (He, O2, N2, CO2) were evaluated in inorganic–organic membranes based on 6FDA–6FpDA and 6FDA–6FpDA:DABA and PMMA-g-silica. PMMA was grafted onto the silica to make it miscible with 6FDA-based polyimide after surface treatment with γ-MPS. The PMMA-g-silica showed greater dispersion than did the pure silica particles in the polymer matrix. The two types of polyimide polymer had similar trends with respect to gas transport properties. The increase in permeation was attributed to changes in the free volume distribution up to 1wt% silica. Above 1wt%, the permeabilities decreased as a result of reduced effective area for gas transport. The selectivities decreased when PMMA-g-silica content increased. However, the selectivity of CO2 in 6FDA–6FpDA was enhanced because of a strong interaction between PMMA and polar gas.
To enhance the transport properties of gas separation membrane, we prepared 6FDA-6FpDA based polyimide membrane with PMMA-graft-silica nanoparticles. The silica was grafted PMMA which is miscible with 6FDA-based polyimide after surface treatment by 3-methacryloxypropyltrimethoxysilane (gamma-MPS). The untreated silica/6FDA-6FpDA membrane showed greater permeability and less selectivity than PMMA-g-silica/6FDA-6FpDA clue to its low dispersion. The transport properties of PMMA-g-silica/6FDA-6FpDA membrane were measured as a function of filler concentration. These membranes were evaluated using pure gases (He, O-2, N-2, CO2). The increase in permeation was attributed to changes in the free volume distribution until 1 wt%. After 1 wt%, the permeability was decreased by excess silica which decreased effective area in polymer matrix. The selectivity was decreased with increasing permeability on the whole. However, the selectivity of CO2 showed more enhance value.
It is important to identify and to test serologically active antigens, so as to devise a cocktail of the best antigens or peptides.We searched for antigens that have serodiagnostic utility using two-dimensional fractionation of sonic extracts from Mycobacterium tuberculosis and probing with pools of sera from healthy subjects and patients with tuberculosis (TB).Reactive protein spots with patient sera were identified by tandem mass spectrometry.Three proteins, Rv0652, Rv2626c, and Rv3418c, which have not previously been described as serologic targets, were identified.Rv0652 protein among them was expressed in Escherichia coli and serum IgG antibodies against this antigen were measured in 150 patients with pulmonary TB and in 115 healthy subjects.The sensitivity and specificity were 39% and 92%, respectively.These results suggest that a newly identified protein, Rv0652 may be a valuable candidate to be included in a cocktail test kit for TB diagnosis.
Mycobacterium tuberculosis likely reside within a granuloma as a dormant state. An area of necrosis forms at the center of lung granulomas. Within this area, the bacteria are deprived of nutrients and exposed to harsh conditions, including low pH and anoxia. The response of M. tuberculosis to low pH and low oxygen conditions was investigated in both cellular and extracellular proteins by two-dimensional polyacrylamide gel electrophoresis analysis and MALDI-TOF. Several proteins intensively expressed under low pH and/or hypoxic conditions were found. In the culture filtrate, PhoS1 (Rv0934) and ScoB (Rv2503c) were found in significant amounts under both the low oxygen and acidic stress conditions. These results indeed extend our understanding of acidic response as well as hypoxic in M. tuberculosis and provide an important insight into physiology of the latent bacilli.
Little information is available on the identification and characterization of the upstream regulators of the signal transduction cascades for Mycobacterium tuberculosis (M. tbc)-induced ERK 1/2 activation and chemokine expression. We investigated the signaling mechanisms involved in expression of CCL3 /MIP-1 and CCL4/MIP-1 in human primary monocytes infected with M. tbc. Methods: MAP kinase phosphorylation was determined using western blot analysis with specific primary antibodies (ERK 1/2, and phospho-ERK1/2), and the upstream signaling pathways were further investigated using specific inhibitors. Results: An avirulent strain, M. tbc H37Ra, induced greater and more sustained ERK 1/2 phosphorylation, and higher CCL3 and CCL4 production, than did M. tbc H37Rv. Specific inhibitors for mitogen-activated protein kinase (MAPK) kinase (MEK; U0126 and PD98059) significantly inhibited the expression of CCL3 and CCL4 in human monocytes. Mycobactetia-mediated expression of CCL3 and CCL4 was not inhibited by the Ras inhibitor manumycin A or the Raf-1 inhibitor GW 5074. On the other hand, phospholipase C (PLC) inhibitor (U73122) and protein kinase C (PKC)specific inhibitors (Go6976 and Ro31-8220) significantly reduced M. tbc-induced activation of ERK 1/2 and chemokine synthesis. Conclusion: These results are the first to demonstrate that the PLC-PKC-MEK-ERK, not the Ras-Raf-MEK-ERK, pathway is the major signaling pathway inducing M. tbc-mediated CCL3 and CCL4 expression in human primary monocytes.