Tin whisker growth, which may lead to short circuits and current leakage, is a serious issue in electronics components. Polyurethane-based conformal coatings have been seen as an effective candidate ...to mitigate the tin whisker growth. To better understand the effect of such coatings, this study exposed the tin-plated copper coupons coated with i) moisture cured polyurethane (PU) and ii) dual UV/moisture cured polyurethane acrylate (PUA), for long-term (up to 5000 h) high-temperature and high-humidity (HTHH) storage (85 °C and 85%RH, respectively). After HTHH storage, microstructural developments in the tin layer, coating degradation, tin surface reaction, and coating adhesion to tin surface were analyzed to compare the tin whisker mitigation behavior. In order to improve the coating adhesion, tin surface was also treated with a silane adhesion promoter before coating was applied. Furthermore, the effect of electron beam irradiation was investigated as it degraded the coating properties and adhesion. The results show that maintaining good adhesion and suppressing the degradation of mechanical properties of conformal coatings during various environmental exposures are essential for enhanced tin whisker mitigation.
•Two types of polyurethane-based conformal coatings are evaluated for tin whisker mitigation capacity.•Tin whisker growth mechanism under the protection of an overlying conformal coating is discussed.•Conformal coatings are degraded during the extended thermal and humid aging conditions (85 °C/85%RH, up to 5000 h).•Coating adhesion is improved on tin surface via its silane treatment that provides long-term protection from tin whiskers.•Effect of the electron beam irradiation on conformal coatings is evaluated for their tin whisker mitigation capacity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Both photo-oxidation and photosynthesis manifest a strong interaction between nanoparticles and photons due to the large surface area-to-volume ratio. The final sizes of the semiconductor ...nanocrystals are determined by the photon energy during these phenomena. The photosynthesis is demonstrated in a Si-rich oxide and is similar to thermal synthesis, which involves the decomposition of SiO
x
into Si and SiO
2, that is well known and often employed to form Si or Ge nanocrystals embedded in SiO
2 by annealing SiO
x
at high temperature. However, photosynthesis is much faster, and allows the low-temperature growth of Si nanocrystals and is found to be pronounced in the SiO nanopowder, which is made by thermal CVD using SiH
4 and O
2. The minimum laser power required for the photosynthesis in the SiO nanopowder is much lower than in the Si-rich oxide formed by the co-sputtering of Si and SiO
2. This is attributed to the weak bond strength of Si–Si and Si–O in the SiO nanopowder. Photosynthesis, which can control the size and position of Si nanocrystals, is a novel nanofabrication technique making the best use of the strong interaction between photons and nanoparticles.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The purpose of this study is to evaluate whether the range of motion exercise of the temporo-mandibular joint (jaw ROM exercise) with a hot pack and massage of the masseter muscle improve biting ...disorder in Duchenne muscular dystrophy (DMD). The subjects were 18 DMD patients (21.3+/- 4.1 years old). The jaw ROM exercise consisted of therapist-assisted training (2 times a week) and self-training (before each meal every day). The therapist-assisted training consisted of the application of a hot pack on the cheek of the masseter muscle region (15 minutes), the massage of the masseter (10 minutes), and jaw ROM exercise (5 minutes). The self-training involved jaw ROM exercise by opening the mouth to the maximum degree, ten times. These trainings continued for six months. Outcomes were evaluated by measuring the greatest occlusal force and the distance at the maximum degree of mouth opening between an incisor of the top and that of the bottom. Six months later, the greatest occlusal force had increased significantly compared with that at the start of jaw ROM exercise (intermediate values: from 73.8N to 97.3N) (p = 0.005) as determined by the Friedman test and Scheffi's nonparametric test. The patients' satisfaction with meals increased. However, the maximum degree of mouth opening did not change after six months of jaw ROM exercise. Jaw ROM exercise in DMD is effective for increasing the greatest occlusal force.
: The optimal amounts of 1‐hydroxybenzotriazole (HOBt), 3,4‐dihydro‐3‐hydroxy‐4‐oxo‐1,2,3‐benzotriazine (HOOBt) and 1‐hydroxy‐7‐azabenzotriazole (HOAt) for enhancement of peptide coupling mediated by ...1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide (EDC) hydrochloride in alcoholic solvents were found to be less than equimolar against the carboxyl component or the carbodiimide. In comparison with the use of equimolar additives, the use of less equimolar ones was more effective in suppressing the competitive ester formation and in increasing the yield of desired peptides. EDC hydrochloride/around 0.1 equimolar HOAt or HOOBt were efficient reagents for peptide synthesis in the media.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
The SiO x thin film with a thickness of about 1 mum was formed on a GaAs substrate by bar-coating with the organic solution of the SiO x nanoparticles (~40 nm). The as-formed SiO x thin film consists ...of the SiO x nanoparticles; thus the thin film is macroscopically discontinuous and is referred to as a nanoparticle thin film. Although there were no silicon (Si) nanocrystals in the as-formed SiO x nanoparticle thin film, Si nanocrystals were observed by Raman scattering measurement after the thin film was exposed to the laser beam. The growth of Si nanocrystals by laser irradiation is referred to as photosynthesis. The photosynthesis of Si nanocrystals is found to be a self-limiting process. After the average size reaches a certain value, further increase of irradiation time or laser power does not increase the average size. The photosynthesis is similar to the thermal synthesis of Si nanocrystals from SiO x but much faster and low-temperature growth of Si nanocrystals from SiO x . Furthermore, the laser irradiation makes nanoparticles larger by merging. This suggests a possibility of low-temperature formation of a Si-nanocrystal array embedded in a SiO 2 thin film. Such a structure has many potential device applications
Nanoparticle (mercury telluride (HgTe))–single-stranded (ss) DNA complex has been synthesized using an electrodeposition technique. As demonstrated by transmission electron microscopic measurements, ...the morphology of these particles is found to depend upon the ssDNA sequence. The surface feature of HgTe–ssDNA deposit gives an appearance of nanostars with an average size as 1.4
nm and exhibits the single crystalline cubic phase, contrary to the polydispersity and polycrystallinity observed with HgTe nanoparticles alone. The change in infrared absorption band of ssDNA as a consequence of its association with HgTe nanoparticles have been confirmed from Fourier transform infrared spectroscopic measurements. Photoluminescence (PL) at 300
K of these nanostars have yielded a unique single PL of line width 8
nm at wavelength 548.4
nm
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Polyurethane (PU) is a good candidate to be used as conformal coatings for space electronic components and boards due to its manufacturability and desirable mechanical properties. It also keeps tin ...whiskers from growing on the tin-rich surfaces under a long-term usage that will ultimately result in electrical failure. PU coating can, however, be susceptible to the irradiation damage in space environment that ultimately alters its chemical structure and mechanical behavior. In this study, four variations of PU-based coatings (PU filled with and without nanosilica particles; polyurethane acrylate (PUA) filled with and without nanosilica particles) were investigated to understand the irradiation damage on chemical structure and the corresponding mechanical properties under three electron beam irradiation fluences (1 × 1014 cm−2, 1 × 1015 cm−2, 1 × 1016 cm−2). Infrared spectroscopy was used to examine the degradation of chemical bonding with irradiation. Microphase separation, the degree of curing, and molecule chain mobility were examined via differential scanning calorimetry (DSC) by monitoring the shift in glass transition temperatures after the irradiation. The electron beam irradiation on PU films resulted in the quinone structure formation whereas, on PUA film, microphase separation increased, thereby making both films stronger and stiffer, but less ductile and more brittle. As a result, PU and PUA coatings under a high fluence of irradiation will be more prone to tin whisker penetration. This study also shows the potential effect of nanosilica on retarding the irradiation damage in PU and PUA films.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The binding of urokinase-type plasminogen activator (uPA) to its receptor (uPAR) has been implicated in cancer invasion and metastasis. This activity is known to be regulated by several inhibitors ...such as plasminogen activator inhibitors (PAIs). To elucidate the participation of the uPA system in the malignant behaviour of squamous cell carcinoma (SCC) in the oral cavity, uPA, uPAR, PAI-1 and -2 expression and localisation in 34 primary oral cancers were examined immunohistochemically. The results were then compared with clinicopathological findings. The positive rates of uPA, uPAR, PAI-1 and -2 expression were 23.5, 29.4, 29.4 and 11.8%, respectively. uPA expression correlated with mode of cancer invasion according to Yamamoto–Kohama’s criteria (
p
<
0.01) and with secondary regional lymph node metastasis. uPAR expression also correlated with mode of invasion. In particular, the tumours of both uPA- and uPAR-positive uPA
(+)/uPAR
(+) cases were highly invasive. In the present study, neither PAI-1 nor PAI-2 expression correlated with clinicopathological parameters. However, PAI-2 negative cases of uPA
(+)/uPAR
(+) were significantly more invasive (
p
<
0.0001). Such uPA
(+)/uPAR
(+)/PAI-2
(−) cases almost always showed secondary lymph node metastasis (
p
<
0.01). These results indicate that the uPA system plays a significant role in the invasive and metastatic processes of oral SCC, and that this system may be a powerful aid in evaluating the clinical course or prognosis of patients with oral cancer.
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IJS, IMTLJ, KILJ, KISLJ, NUK, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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