Showing papers by "Hua Zhang published in 2005"

Micrometric direct-write methods for patterning conductive material and applications to flat panel display repair

Abstract: A new, low temperature method for directly writing conductive metal traces with micron and sub-micron sized features. In this method, a flat beam is used, such as an AFM cantilever, with or without a tip, to draw traces of metal precursor ink onto a substrate. The dimensions of the metal traces can be directly controlled by the geometry of the cantilever, so that one can controllably deposit traces from 1 micron to over 100 microns wide with microfabricated cantilevers. Cantilevers with sharp tips can be used to further shrink the minimum features sizes to sub-micron scale. The height of the features can be increased by building layers of similar or different material. To obtain highly conductive and robust patterns with this deposition method, two general ink formulation strategies were designed. The key component of both ink systems is nanoparticles with diameters less than 100 nm. Because nanoparticles typically have significantly lower melting points than the bulk material, one can fuse, sinter, or coalesce collections of discrete particles into continuous (poly)crystalline films at very low temperatures (less than about 300° C., and as low as about 120° C.). In the first strategy, one can disperse hydrocarbon-capped nanoparticles in a suitable solvent, deposit them on a surface in the form of a pattern, and then anneal the film by heating to form continuous metallic patterns. In the second strategy, one can deliver metal compounds to the surface in the presence of a reducing matrix and then form nanoparticles in situ by heating that subsequently coalesce to form continuous metallic patterns. In studies with platinum and gold inks, both nanoparticle-based methods yield micron sized traces on glass and oxidized silicon that have low resistivity (4 microohm·cm), and excellent adhesion properties.

Toughening of nylon‐6 with epoxy‐functionalized acrylonitrile‐butadiene‐styrene copolymer

Abstract: Glycidyl methacrylate (GMA) functionalized acrylonitrile-butadiene-styrene (ABS) copolymers have been prepared via an emulsion polymerization process. The epoxy-functionalized ABS (e-ABS) particles were used to toughen nylon-6. Molau tests and FTIR results showed the reactions between nylon-6 and e-ABS have taken place. Scanning electron microscopy (SEM) displayed the compatibilization reaction between epoxy groups of e-ABS and nylon-6 chain ends (amine or carboxyl groups), which improve disperse morphology of e-ABS in the nylon-6 matrix. The presence of only a small amount of GMA (1 wt %) within the e-ABS copolymer was sufficient to induce a pronounced improvement of the impact strength of nylon-6 blends; whereas further increase of the GMA contents in e-ABS resulted in lower impact strength because of the crosslinking reaction between nylon-6 and e-ABS, resulting in agglomeration of the ABS particles. SEM results showed shear yielding of the nylon-6 matrix and cavitation of rubber particles were the major toughening mechanisms.

Direct-write nanolithography with stamp tips: fabrication and applications

Abstract: A novel method for fabricating polymer, e.g., polydimethylsiloxane (PDMS),-coated dip-pen nanolithographic (DPN) stamp tips. This kind of tip adsorbed chemicals (“inks”) easily and was used to generate DPN nanopatterns which were imaged with the same tip after DPN process. This method built a bridge between micro-contact printing (μCP) and DPN, making it possible for one to easily generate smaller structures of any molecules which have been patterned by the μCP technique. The easy tip-coating and writing process enriches the state-of-the-art DPN technique. The sub-100 nm DPN resolution obtained by using this kind of novel tip is comparable to that with a conventional Si 3 N 4 probe tip. Importantly, the unique stamp tip was able to transfer solvent (e.g., liquid “ink”) onto a substrate, resulting in fabrication of hollow nanostructures with only one DPN holding/writing step. Inks comprising metals and sol-gel materials are noted, as well as applications in photomask repair, enhancement, and fabrication.

Stamps with micrometer-and nanometer-scale features and methods of fabrication thereof

Abstract: Stamps and methods of making stamps for applications in anti-counterfeiting and authentication. The stamps are relatively small in size and feature nanoscale and microscale identification regions and features. High throughput manufacturing and high resolution methods are used to make the stamps including electron beam lithography and optical lithography. Anti-fouling coatings can be applied.

Hasubanan type alkaloids from Stephania longa.

Abstract: Thirteen new hasubanan type alkaloids, stephalonines A−I (1−9), norprostephabyssine (15), isoprostephabyssine (16), isolonganone (18), and isostephaboline (21), as well as nine known ones, were isolated from the whole plants of Stephania longa, a well-known traditional Chinese medicine. Their structures were elucidated on the basis of spectroscopic data and chemical methods.

Direct-write nanolithography method of transporting ink with an elastomeric polymer coated nanoscopic tip to form a structure having internal hollows on a substrate

Abstract: A novel method of transporting ink to a substrate with dip-pen nanolithographic (DPN) stamp tips coated with polymer (e.g., polydimethylsiloxane (PDMS), etc.). This kind of tip adsorbs chemicals (“inks”) easily and is used to generate DPN nanopatterns that are imaged with the same tip after a DPN process. This method builds a bridge between micro-contact printing (μCP) and DPN, making it possible for one to easily generate smaller structures of any molecules that have been patterned by the μCP technique. The easy tip-coating and writing process enriches the state-of-the-art DPN technique. The sub-100 nm DPN resolution obtained by using this kind of novel tip is comparable to that with a conventional Si 3 N 4 probe tip. Importantly, the unique stamp tip was able to transfer solvent (e.g., liquid “ink”) onto a substrate, resulting in fabrication of hollow nanostructures with only one DPN holding/writing step. Inks comprising metals and sol-gel materials are noted, as well as applications in photomask repair, enhancement, and fabrication.

Effects of oxidized low density lipoprotein on the growth of human artery smooth muscle cells

Abstract: BACKGROUND: Studies have shown that oxidized low density lipoprotein (ox-LDL) promotes the pathogenesis and development of atherosclerosis (AS), and that the proliferation, migration and phenotype alteration of vascular smooth muscle cells (vSMCs) into foam cells are critical changes in AS It is proposed that ox-LDL might play a novel role in the pathologic process of vSMCs The present study was performed ex vivo to investigate the effects of ox-LDL on the growth of cultured human vSMCs METHODS: Using NaBr density gradient centrifugation, LDL from human plasma was isolated and purified ox-LDL was produced from LDL after being incubated with CuSO4 ox-LDL was then added to the culture medium at different concentrations (25 microg/ml, 50 microg/ml, 75 microg/ml, 100 microg/ml, 125 microg/ml, and 150 microg/ml) for 7 days The influence of ox-LDL on vSMC growth was observed from several aspects as growth curve, mitosis index, lipid staining, and in situ determination of apoptosis The digital results were analyzed with SPSS 100 RESULTS: The ox-LDL produced ex vivo had a good purity and optimal oxidative degree, which was similar to the intrinsic ox-LDL in atherosclerotic plaque ox-LDL at a concentration of 25 microg/ml demonstrated the strongest proliferation At the concentration of 125 microg/ml, ox-LDL suppressed the growth of vSMCs At concentrations of 25 microg/ml and 50 microg/ml, ox-LDL presented powerful mitotic trigger When the concentration of ox-LDL increased, the mitotic index of vSMCs decreased gradually ox-LDL induced more foam cells from vSMCs with rich intracellular lipid accumulation at concentrations of 25 microg/ml and 50 microg/ml ox-LDL at higher concentrations induced more apoptotic vSMCs CONCLUSIONS: ox-LDL at lower concentrations may trigger proliferation and phenotype alteration into foam cells of vSMCs, and at higher concentrations it may induce apoptosis in vSMCs ox-LDL plays an important role in the pathogenesis and development of atherosclerosis by its effect on vSMCs proliferation, phenotype alteration and apoptosis

A functional variant of Fcγ receptor IIIA is associated with rheumatoid arthritis in individuals who are positive for anti-glucose-6-phosphate isomerase antibodies

Abstract: Anti-glucose-6-phosphate isomerase (GPI) antibodies are known to be arthritogenic autoantibodies in K/B×N mice, although some groups have reported that few healthy humans retain these antibodies. The expression of Fcγ receptors (FcγRs) is genetically regulated and has strong implications for the development of experimental arthritis. The interaction between immune complexes and FcγRs might therefore be involved in the pathogenesis of some arthritic conditions. To explore the relationship between functional polymorphisms in FcγRs (FCGR3A-158V/F and FCGR2A-131H/R) and arthritis in individuals positive for anti-GPI antibodies, we evaluated these individuals with respect to FCGR genotype. Genotyping for FCGR3A-158V/F and FCGR2A-131H/R was performed by PCR amplification of the polymorphic site, followed by site specific restriction digestion using the genome of 187 Japanese patients with rheumatoid arthritis (including 23 who were anti-GPI antibody positive) and 158 Japanese healthy individuals (including nine who were anti-GPI antibody positive). We report here on the association of FCGR3A-158V/F functional polymorphism with anti-GPI antibody positive status. Eight out of nine healthy individuals who were positive for anti-GPI antibodies possessed the homozygous, low affinity genotype FCGR3A-158F (odds ratio = 0.09, 95% confidence interval 0.01–0.89; P = 0.0199), and probably were 'protected' from arthritogenic antibodies. Moreover, among those who were homozygous for the high affinity genotype FCGR3A-158V/V, there were clear differences in anti-human and anti-rabbit GPI titres between patients with rheumatoid arthritis and healthy subjects (P = 0.0027 and P = 0.0015, respectively). Our findings provide a molecular model of the genetic regulation of autoantibody-induced arthritis by allele-specific affinity of the FcγRs.

Edit and evaluation of Mandarin sentence materials for Chinese speech audiometry

Abstract: Objective To edit the sentence list for mandarin speech test materials （MSTM） and to test their equivalence in order to use the list as routine clinical speech tests for evaluation of cochlear implants and hearing aids in different stages of the intervention and rehabilitation. Methods Firstly, two groups of professionals were set up ： one for establishing the principles of the edit, another for experiments. The criteria to guide the selection of spoken sentences were as following：①suitable for everyday speech audiometry, esp. clinically usage;② a normal sampling of everyday spoken sentences in mandarin. Totally, 300 sentences were selected in 30 lists for the experiment. The record cassette was used by a male speaker. The college students （54 persons, 54 ears） with normal hearing participated in the equivalence test. Two statistic methods were used for equivalence analysis. Results Through speech tests and statistic analysis, 2 sets with 29 lists （290 sentences） were selected as our equivalent lists for further evaluation and clinical trial. Conclusions By setting up the strict criteria of selecting sentences, speech test method and statistic analysis, 2 sets of 29 lists （290） sentences were chosen as our speech evaluation materials, but it was necessary for further analysis in different laboratories and clinics. The sentence lists should also get used for hearing impaired subjects, hearing aid users and cochlear implant recipients. Key words: Speech audiometry; Chinese; Mandarin; Equivalence

Pharmacokinetics of Indomethacin, a Metabolite of Acemetacin, Following a Single dose and Multiple doses Administered as Acemetacin Sustained-Release Tablets in Healthy Male Volunteers

Abstract: The objective of this study was to estimate the pharmacokinetics of the newly developed once-daily acemetacin sustained-release tablets compared with those of the commercial acemetacin sustained-release capsules. Ten male healthy Chinese volunteers were included in the study. The administration schedule was a randomized crossover design. Each volunteer received 90 mg of the tablet or the capsule in the single-dose study, and each received 90 mg of the tablet or the capsule once daily for 6 consecutive days in the multiple-dose study. The areas under the concentration-time curve (AUC0-24 hr), maximal concentrations of indomethacin (Cmax), time to reach peak concentration (Tmax), and elimination half-life (T1/2) values of indomethacin (an active metabolite of acemetacin) were 6.72 ± 0.99 μg.hr/ml, 0.82 ± 0.08 μg/ml, 4.2 ± 0.6, and 10.1 ± 4.2 hr, respectively. The steady-state AUC120-144 hr and steady-state maximal concentration of the tablets increased to 10.33 ± 1.06 μg.hr/ml and 1.14 ± 0.10 μg/ml, respectively. The pharmackinetic parameters (AUC0-24 hr, Cmax, T1/2, and mean residence time) for two formulations were not significantly different but the average Tmax of the tablets was delayed by 1 hr compared with that of the capsules (4.2 ± 0.6 vs. 3.2 ± 0.6 hr, p < 0.05). The mean relative bioavailability of the tablets was 97.9 ± 14.8% compared with that of the capsules. It could be concluded that the pharmacokinetic parameters of the newly developed sustained-release tablets are similar to those of the sustained-release capsules, excluding the Tmax value. A significant correlation was obtained between the in vivo mean absorption rate and the in vitro mean dissolution rate for the newly developed sustained tablets.

Effect of aging time on properties of acrylic impact modifier modified bisphenol A polycarbonate

Abstract: Polycarbonate (PC) was blended with acrylic impact modifiers (AIMs). The effects of modifiers weight fraction on the Izod impact strength and yield strength of PC/AIM blends were investigated. The samples with 4% modifiers were aged under the Tg of PC in an air-circulating oven, and the effects of aging time on impact strength, yield strength, modulus, elongation at break, post yield stress drop (PYSD) values, and morphology of fracture surface were investigated. The effects of aging time on the shape of stress–strain curve were also investigated. The aged samples were heat-treated over the Tg of PC to erase the effects of physical aging. It was found that the drop of impact strength caused by physical aging can be recovered, the increment of yield strength and PYSD value caused by physical aging can only be partly recovered, and the heat-treatment over the Tg of PC caused further increment of modulus. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2715–2724, 2005

[Preparation of doxorubicin-loaded stealth liposomes modified with RGD mimetic and cellular association in vitro].

Abstract: Aim To investigate the possibility of using stealth liposomes modified with arginine-glycine-aspartic acid (RGD) mimetic as the targeted carriers to achieve increased accumulation in tumor and enhanced intracellular delivery for the encapsulated anticancer drugs. Methods RGD mimetic (RGDm) as a ligand for integrins was synthesized and covalently conjugated to the active PEGylated phospholipids (DSPE-PEG-BTC) to form RGDm conjugate (DSPE-PEG-RGDm). Then RGDm-modified SL (RGDm-SL) containing DOX (RGDm-SL-DOX) and SL containing DOX (SL-DOX) were prepared by film dispersion followed by ammonium sulfate gradient method. The pH-sensitive probe, BCECF-AM, was used to study the binding of melanoma cells to DSPE-PEG-RGDm. Flow cytometry and confocal microscopy were performed to evaluate the cellular association or DOX uptake for RGDm-SL-DOX or SL-DOX in vitro. Results The melanoma cells A375 and B16 showed enhanced binding to the immobilized DSPE-PEG-RGDm. The cells treated with RGDm-SL-DOX showed remarkable increase in cellular association or DOX uptake compared with SL-DOX. Conclusion The RGDm-modified SL could be as the targeted carriers to facilitate the delivery of the encapsulated anti-cancer drugs into tumor cells by receptor-mediated way.

[Follow-up study for newborns and infants who failed hearing screening].

Abstract: Objective To study the audiological characteristics of newborns and infants who failed hearing screening Methods One hundred and six infants failed hearing screening received follow-up study with routine audiological evaluations （auditory brainstem response, distortion product otoacoustic emission, tympanometry and visual reinforcement audiometry） Results Sixty-five infants （613% ） of this group were normal hearing subjects and 39（368%） of the infants had hearing loss Two cases （19%） received follow-up by phone Fifteen cases （142%）with conductive hearing loss and 24 cases （226%） with sensorineural hearing loss Thirteen（123%）,14（132%） , 6（57%） , and 6（57%）cases were found to be mild , moderate, severe and profound hearing loss respectively Diagnosis of hearing loss in the thirty- nine infants conducted a prevalence of 0264% （39/14 785） of congenital hearing loss （both binaural and monaural） The hearing level of those cases with severe and profound hearing loss basically did not change, but that of cases with mild and moderate hearing loss changed Conclusions Early identification and intervention of infants with severe and profound hearing loss by 6 months of age were successful Infants with mild and moderate hearing loss should be followed up to six or eight months and received routine audiologic evaluations Key words: Neonatal screening; Evoked potentials, auditory, brain stem; Deafness; Audiometry, evoked response