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Hemostasis, a process which causes bleeding to stop, can be enhanced using chitosan; but the detailed mechanism is unclear. Red blood cells (RBCs) adhere to chitosan because of their opposite charges, but the adhesion force is small, 3.83 pN as measured here using an optical tweezer, such that the direct adhesion cannot be the sole cause for hemostasis. However, it was observed in this study that layer structures of aggregated RBCs were formed next to chitosan objects in both static and flowing environments, but not formed next to cotton and rayon yarns. The layer structure is the clue for the initiation of hemostatsis. Through the supporting measurements of zeta potentials of RBCs and pH's using blood-chitosan mixtures, it is proposed here that the formation of the RBC layer structure next to chitosan objects is due to the reduction of repulsive electric double layer force between RBCs, because of the association of H+ deprotonated from chitosan with COO− on RBC membrane, under the DLVO (Derjaguin-Landau-Verwey-Overbeek) theory. The results are beneficial for designing effective chitosan-based wound dressings, and also for general biomedical applications.
The ability of the aorta to buffer blood flow and provide diastolic perfusion (Windkessel function) is a determinant of cardiovascular health. We have reported cardiac dysfunction indicating downstream vascular abnormalities in young adult baboons who were intrauterine growth restricted (IUGR) at birth as a result of moderate maternal nutrient reduction. Using 3 T MRI, we examined IUGR offspring (eight male, eight female; 5.7 years; human equivalent 25 years) and age-matched controls (eight male, eight female; 5.6 years) to quantify distal descending aortic cross-section (AC) and distensibility (AD). ANOVA showed decreased IUGR AC/body surface area (0.9±0.05 cm2/m2v. 1.2±0.06 cm2/m2, M±s.e.m., P<0.005) and AD (1.7±0.2 v. 4.0±0.5×10−3/mmHg, P<0.005) without sex difference or group-sex interaction, suggesting intrinsic vascular pathology and impaired development persisting in adulthood. Future studies should evaluate potential consequences of these changes on coronary perfusion, afterload and blood pressure.
The Arcminute Cosmology Bolometer Array Receiver (Acbar) is a multifrequency millimeter-wave receiver optimized for observations of the Cosmic Microwave Background (CMB) and the Sunyaev-Zel'dovich (SZ) effect in clusters of galaxies. Acbar was installed on the 2.1 m Viper telescope at the South Pole in January 2001 and the results presented here incorporate data through July 2002. The power spectrum of the CMB at 150 GHz over the range ℓ = 150 — 3000 measured by Acbar is presented along with estimates for the values of the cosmological parameters within the context of ΛCDM models. The inclusion of ΩΛ greatly improves the fit to the power spectrum. Three-frequency images of the SZ decrement/increment are also presented for the galaxy cluster 1E0657–67.
The association between Kawasaki disease (KD) and Attention deficit hyperactivity disorder (ADHD) has rarely been studied. In this study, we investigated the hypothesis that KD may increase the risk of ADHD using a nationwide Taiwanese population-based claims database.
Our study cohort consisted of patients who were diagnosed with KD between January 1997 and December 2005 (N = 651). For a comparison cohort, five age- and gender-matched control patients for every patient in the study cohort were selected using random sampling (N = 3255). The cumulative incidence of ADHD was 3.89/1000 (from 0.05 to 0.85) in this study. All subjects were tracked for 5 years from the date of cohort entry to identify whether or not they had developed ADHD. Cox proportional hazard regression analysis was performed to evaluate 5-year ADHD-free survival rates.
Of all patients, 83 (2.1%) developed ADHD during the 5-year follow-up period, of whom 21 (3.2%) had KD and 62 (1.9%) were in the comparison cohort. The patients with KD seemed to be at an increased risk of developing ADHD (crude hazard ratio (HR): 1.71; 95% confidence interval (CI) = 1.04–2.80; p < 0.05). However, after adjusting for gender, age, asthma, allergic rhinitis, atopic dermatitis and meningitis, the adjusted hazard ratios (AHR) of the ADHD in patients with KD showed no association with the controls (AHR: 1.59; 95% CI = 0.96–2.62; p = 0.07). We also investigated whether or not KD was a gender-dependent risk factor for ADHD, and found that male patients with KD did not have an increased risk of ADHD (AHR: 1.62; 95% CI = 0.96–2.74; p = 0.07) compared with the female patients.
The findings of this population-based study suggest that patients with KD may not have an increased risk of ADHD and whether or not there is an association between KD and ADHD remains uncertain.
Through silicon via (TSV) is the critical structure for three dimensional (3D) integration, which provides vertical interconnection between stacking dies. In TSV structure, large coefficient differences of thermal expansion exist between silicon substrate, dielectric material, and filled metal. Due to the large thermal mismatch, the high thermal stress occurring at the interface of different materials would result in delamination. Therefore, thermal-mechanical reliability is a key issue for 3D integration. In this study, we investigated the thermal-mechanical stress distribution of TSV under the condition of the accelerated thermal cycling loading by finite element analysis based on a 3D model of TSV structure. Due to the thermal expansion, that the TSV structure squeezed the surface area between TSVs at a high temperature resulted in compressive stresses at the surface area between TSVs. Therefore, a proper distance between the stress-sensitive device and the TSV should be kept. The stress analysis shows that the maximum thermal stress occurs in the outside region of TSV interface and in the annular region of TSV at a high temperature and at a low temperature, respectively. This study helps to obtain a clear thermal stress distribution of TSV and possible failure regions can be determined.
The warm white light emission from the MOS capacitor containing the Zr-doped HfO2 high-k thin film on a p-type Si wafer under various post deposition annealing temperatures has been investigated. The light intensity is affected by the annealing temperature and the magnitude of the stress voltage. The annealing temperature changes the defect density and the physical thickness of the high-k stack. The high stress voltage induces the strong light emission because of the passage of a large current through the conductive path. The broad band emission spectrum covers the visible and near IR wavelength range with a large color rendering index. This new light emission device has a very long lifetime of > 1,000 hours at the atmosphere without a protection layer. The device is made of the IC compatible material and fabrication process, which favors the application over a wide range of products.
The crystal structure of a-plane GaN/ZnO heterostructures on r-plane sapphire was investigated by using the XRD and TEM measurment. It was found the formation of (220) ZnGa2O4 and crystal orientation of semipolar (10
3) GaN at GaN/ZnO interface. The epitaxial relation of normal surface direction are the sapphire (1
02) // a-GaN (11
0) and ZnGa2O4 (220) // semi-polar GaN (10
). Beside, the emission peak energy of ZnO appears shift about 60 meV in the GaN/ZnO/GaN heterostructures due to the re-crystallization of ZnO layer with Ga or N atom and the formation of the localized state.
We report a rare case of concurrent myeloid sarcoma and acute fulminant invasive fungal sinusitis in a patient with relapsed acute myeloid leukaemia.
A 73-year-old man was diagnosed with acute myeloid leukaemia and developed relapse one year later. After two courses of azacytidine, he began suffering from a dull pain in the left temporal and orbital regions. Sinus computed tomography showed a localised lesion in the left ethmoid sinus, which rapidly progressed to an extensive intracranial mass within one month. Surgical debridement was performed, and histopathological analysis revealed the coexistence of myeloid sarcoma and acute fulminant invasive fungal sinusitis. The patient responded well to prompt surgical debridement, antifungal medication and radiotherapy.
Coexistence of sinonasal myeloid sarcoma and acute fulminant invasive fungal sinusitis poses an urgent diagnostic and management challenge to clinicians. Timely recognition of this rare comorbid condition is warranted as application of appropriate treatment can save lives.
The aortic pulse wave velocity (PWV) is a useful clinical index to assess the aortic compliance and cardiovascular risk in a noninvasive manner. In this research, our previously developed axial velocity profile method (Yu et al., ) was modified to be more user-friendly and applied to the study of PWV of diabetic patients for the first time, using phase-contrast magnetic resonance imaging (PC-MRI) technique to analyze the spatial and temporal profiles of the axial velocity along the descending aorta for measurement of the aortic PWV. The PWV results from healthy volunteers and diabetic patients were studied and compared. It is shown that the PWV of diabetic patients is much higher than that of health volunteers, the aortic compliance of diabetic patients is substantially worse than that of health volunteers. These results are in good agreement with early studies using different measurement techniques of PWV. The axial velocity profile method is again validated and proven to be a useful tool of long-term prognosis for patients with diabetes mellitus or hypertension.
Background: The Consortium to Establish a Registry for Alzheimer's Disease Neuropsychological Assessment Battery (CERAD-NAB) offers information on the clinical diagnosis of Alzheimer's disease (AD) and gives a profile of cognitive functioning. This study explores the effects of age, education and gender on participants' performance on eight subtests in the Chinese-Cantonese version of the CERAD-NAB.
Methods: The original English version of the CERAD-NAB was translated and content-validated into a Chinese-Cantonese version to suit the Hong Kong Chinese population. The battery was administered to 187 healthy volunteers aged 60 to 94 years. Participants were excluded if they had neurological, medical or psychiatric disorders (including dementia). Stepwise multiple linear regression analyses were performed to assess the relative contribution of the demographic variables to the scores on each subtest.
Results: The Cantonese version of CERAD-NAB was shown to have good content validity and excellent inter-rater reliability. Stepwise multiple regression analyses revealed that performances on seven and four out of eight subtests in the CERAD-NAB were significantly influenced by education level and age, respectively. Age and education had significant effects on participants' performance on many tests. Gender also showed a significant effect on one subtest.
Conclusions: The preliminary data will serve as an initial phase for clinical interpretation of the CERAD-NAB for Cantonese-speaking Chinese elders.
We report very small interdiffusion and surface segregation of Si in δ-doped GaAs, A10.3Gao.7As and Quantum Wells grown at 580 C by Gas Source Molecular Beam Epitaxy. Capacitance-Voltage profiles of δ-doped layers are 38 Å wide for growth at 580 C and further, insignificant profile narrowing is observed at 530C and below. Much wider profiles are observed at equivalent substrate temperature for As4 growth. Atomic diffusion of Si in δ-doped Al0.3Ga0.7As is found to have a rate of D0=5× 10−cm2/sec with an activation energy of 1.8 eV.
We demonstrate the operation of a high-speed optically addressed spatial light modulator utilizing a hydrogenated amorphous silicon photosensor and a ferroelectric liquid crystal modulator. The device has numerous optical parallel processing and interconnect applications. It combines desirable resolution, switching speed, size, and contrast characteristics. The devices are driven by a square-wave voltage, such that read and write operations take place under reverse bias, and an erase operation occurs under forward bias. The capacitance associated with the photosensor plays a critical role in the device performance.
Amorphous SiNx:H thin films were prepared by plasma-enhanced CVD process. The effects of preparation conditions on the optical properties, compositions, and deposition rates of a-SiNx:H films were systematically studied by means of spectrophotometer, ellipsometer, and infrared spectroscopy measurements. It has been found that the refractive indices decrease with increasing the NH3 gas flow rate and the rf power, and increase with increasing the electrode spacing. Conversely, the deposition rates increase with increasing the NH3 gas flow rate and the rf power, and decrease with increasing the electrode spacing. There was no obvious effect of substrate temperatures ranging from 250 to 320°C on the optical properties and deposition rates of a-SiNx :H films. The decrease of the refractive index and the increase of the deposition rate were due to the increase of the nitrogen composition x occurring in the a-SiNx:H films. Refractive indices n and extinction coefficients k of a-SiNx:H films can be varied from n = 3.6 and k = 0.1 for x = 0 (pure a-Si:H) to n = 1.8 and k = 0 for x = 1.33 (pure a-Si3 N4:H) at the wavelength of 633 nm.
Transmission election microscopy studies show that nitrogen doping changes the misfit dislocation structure in ZnSe films and decreases the density of threading dislocations. There appears to be a critical N doping concentration of ∼ 1.5 × 1018/cm3 above which the density of threading dislocations increases again. Samples with high N doping concentrations (> 1019/cm3 ) also show compensation or decrease in the carrier density of the films. Our TEM observations show that N doping can produce low energy nucleation sites for the 60° misfit dislocations at or close to the ZnSe/GaAs interface.
Elemental Vapor Transport Epitaxy (EVTE) is a novel technique for semiconductor manufacturing, which combines the advantages of Molecular Beam Epitaxy (MBE) and Vapor Phase Epitaxy (VPE). EVTE provides a high level of elemental flux control, scaling to large deposition areas, and elimination of elemental Ga source related oval defects. EVTE has been successfully applied to the deposition of III-V and II-VI thin films and heterostructures. Design considerations and evaluations of the novel EVTE elements: elemental flux regulating valve operating at temperatures >1250°C with demonstrated response times less than 1 second and elemental flux distribution manifold are presented. The calculated operational parameters for EVTE are in good agreement with the observed experimental results.
The formation of high resistivity (> 107 Ω□) regions in GaAs-AlGaAs HBT and SEED structures by oxygen and hydrogen ion implantation is described. Multiple energy implants in the dose range 1013 cm−3 (for O+) and 1015 cm−2 (for H+), followed by annealing around 500°C are necessary to isolate structures ∼2 μm thick. In each case, the evolution of the sheet resistance of the implanted material with annealing is consistent with a reduction in hopping probabilities of trapped carriers between deep level states for temperatures up to ∼600°C, followed by significant annealing of these deep levels. A comparison of the relative thermal stability of O+ or H+ ion implantisolated p+ material is given. Small geometry (2 × 9 μm2) HBTs exhibiting current gain of 44 and cut-off frequency fT as high as 45 GHz are demonstrated using implant isolation.
Shallow and deep electronic defects in MOCVD-grown GaN were characterized by variable temperature Hall effect measurements, deep level transient spectroscopy (DLTS) and photoemission capacitance transient spectroscopy (O-DLTS). Unintentionally and Si-doped, n-type and Mg-doped, p-type GaN films were studied. Si introduces a shallow donor level into the band gap of GaN at ∼Ec - 0.02 eV and was found to be the dominant donor impurity in our unintentionally doped material. Mg is the shallowest acceptor in GaN identified to date with an electronic level at ∼Ev + 0.2 eV. With DLTS deep levels were detected in n-type and p-type GaN and with O-DLTS we demonstrate several deep levels with optical threshold energies for electron photoemission in the range between 0.87 and 1.59 eV in n-type GaN.
The Taiwan Power Company's (TPC) coal combustion power plants produced approximately 1 million tons of class F fly ash in 1988 but only 25% of it was effectively utilized. Accordingly, this study investigated the use of separation techniques to improve the quality of the fly ash in order to increase its application. In the experiment, the fly ash was dry-sieved through sieves No. 200, 300 and 400 mesh respectively. The chemical, physical and some of the engineering properties of those classified class F fine fly ashes were ascertained.
We report systematic characterizations of flicker noise in GaN based MODFETs. Flicker noise was measured across the channel of the devices from room temperature to 130 K. The voltage noise power spectra, Sv(f) were found to be proportional to l/f, where γ depends on the device temperature as well as the gate bias. Study of Sv(f) as a function of the biasing condition was conducted in detail and was found to vary as VD2/(VG-VT)β where β changes with temperature from about 2.1 at room temperature to about 0.9 at 130K. Analyses of the data showed that the noise originated from thermal activation of carriers to localized states in the channel area. The data suggested that the trapping and detrapping of carriers did not lead to fluctuations in the carrier concentration as postulated in the McWhorter's model. However, more work is needed to determine if surface mobility fluctuations played key role in the l/f noise.