Thermally expandable microcapsules for polymer foaming—Relationship between expandability and viscoelasticity

A new thermally expandable microcapsule was developed for use with foaming polypropylene (PP) by injection molding and extrusion processes at operating temperatures above 200°C. The microcapsule consists of a blowing agent as the core and a shell polymer. The rheological properties of the shell polymer were controlled by a crosslinking agent to design the expandability and shrinkage. The effects of rheological properties on the expandability and the surface appearance of foam products were thoroughly investigated. It was found that storage modulus G′ and tan δ significantly affected the expandability and shrinkage and were controllable through crosslinking polymerization. Visual observation of batch foaming, rheological measurement, and experiments of foam injection molding and extrusion elucidated the existence of the optimal degree of crosslinking that could realize more than 30% density reduction while maintaining a smoothsurface at PP foam injection molding and extrusion. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers     

通过水溶液还原法用抗坏血酸制备纳米铜颗粒(英文)

通过水溶液还原法用抗坏血酸还原Cu2+制备纳米铜颗粒,并研究溶液pH和Cu2O平均粒径对纳米铜颗粒制备的影响。在溶液pH值为3、5和7时,可制得铜颗粒,并且在pH=7时制得的铜颗粒粒径最小。在溶液pH为9和11时无法制得铜颗粒。Cu2O的平均粒径能影响铜粉的粒径。Cu2O的平均粒径越大,得到的铜颗粒越大。通过对反应过程中不同时间点收集的样品进行XRD分析,可探索出反应的进程。在反应过程中,Cu(OH)2首先作为前驱体出现,然后被还原为Cu2O,最后被还原为铜颗粒。     

Lipid and fatty acid compositions of a novel docosahexaenoic acid-producing marine bacterium

An unidentified bacterial strain, SCRC-21406, isolated from the intestine of a marine fish, Glossanodon semifasciatus, produced docosahexaenoic acid at 23% (mol/mol) [=28% (w/w)] of total fatty acids in a medium containing 0.5% (wt/vol) peptone and 0.1% (wt/vol) yeast extract at 12°C under atmospheric pressure. The cell yield was 0.43 g/L. The major lipids of the strain were phosphatidylethanolamine and phophatidylglycerol. Docosahexaenoic acid was localized at the sn-2 positions of both phospholipids. The amounts of polyunsaturated fatty acids other than docosahexaenoic acid were extremely small [<3% (mol/mol)]. Monousaturated fatty acids of the cis-7, cis-9 and cis-11 types were detected.     

Sealing effects of anodic oxide films formed on Mg-Al alloys

Mg alloys were anodized in alkaline NaOH solutions with various additives as a non-chromate method. Specimen AZ91 was anodized at a potential that produced a strong surface dissolution reaction and generated a large amount of Mg(OH)₂. The effect of sealing after anodizing was investigated, focusing on the effects of sealing time, temperature and solution conditions. The current density decreased with increasing A1(OH)₃ concentration in 1 M NaOH solution during anodizing; sparking occurred at potentials above 80 V. The best corrosion resistance with anodizing in 1 M NaOH solution occurred at a potential of 4 V, which caused the strongest active dissolution reaction. The sealing effect improved with increasing time and temperature, and corrosion resistance was proportional to the relative ratio of Mg(OH)₂. If the oxygen thickness observed by EDX equaled the film thickness, the film formed at 4 V in 1 M NaOH was 10–15 Μm thickness. The optimum corrosion resistance in sealing at various solutions after anodizing was 1M-NaOH solution.     

A novel decomposition technique of friable asbestos by CHClF2-decomposed acidic gas

Asbestos was widely used in numerous materials and building products due to their desirable properties. It is, however, well known that asbestos inhalation causes health damage and its inexpensive decomposition technique is necessary to be developed for pollution prevention. We report here an innovative decomposition technique of friable asbestos by acidic gas (HF and HCl) generated from the decomposition of CHClF(2) by the reaction with superheated steam at 800 degrees C. Chrysotile-asbestos fibers were completely decomposed to sellaite and magnesium silicofluoride hexahydrate by the reaction with CHClF(2)-decomposed acidic gas at 150 degrees C for 30 min. At high temperatures beyond 400 degrees C, sellaite and hematite were detected in the decomposed product. In addition, crocidolite containing wastes and amosite containing wastes were decomposed at 500 degrees C and 600 degrees C for 30 min, respectively, by CHClF(2)-decomposed acidic gas. The observation of the reaction products by phase-contrast microscopy (PCM) and scanning electron microscopy (SEM) confirmed that the resulting products did not contain any asbestos.     

High‐speed imaging of laser intensity distribution using an acousto‐optic deflector

An acousto‐optic laser deflector was used to image the intensity distribution of a continuous wave laser of microsecond order. Undeflected light was blocked while the deflected light was directed to a CCD camera, which allowed imaging of the incident laser intensity distribution of microsecond order. Experiments using a test pattern showed that there was no distortion in the deflected image. The resolution limit, estimated from diffractive effects, was about 0.2 mrad. Using this method of high‐speed imaging, density variations accompanying laser‐induced breakdown in air were visualized by shadowgraphy and interferometry. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(3): 55–61, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20386     

The localization of aldosterone-producing adenoma on computed tomography--a comparative study with adrenal scintigraphy and plasma aldosterone concentration in the adrenal or renal vein

The evaluation of computed tomography (CT) for detecting aldosterone-producing adenoma in primary aldosteronism was performed by comparison with adrenal scintiscan; determination of aldosterone in adrenal or renal veins, retroperitoneal pneumography and adrenal venography was reliable for diagnosis of adrenal tumors in pheochromocytoma or Cushing's syndrome, but not so effective for small adenoma of primary aldosteronism. An abdominal CT scan was performed on six patients with primary aldosteronism, one with idiopathic hyperaldosteronism and one with glucocorticoid responsive hyperaldosteronism; in an attempt to evaluate the utility of this noninvasive procedure. Diagnosis of hyperaldosteronism was made by demonstrating the elevated plasma aldosterone concentration and aldosterone secretion rate, normal excretion rate of urinary 17-OHCS and 17-KS, and low plasma renin activity. The CT scan correctly predicted unilateral adrenal adenoma in all the patients with primary aldosteronism of which the findings were identical to those demonstrated by surgery. The diameter of these tumors ranged from 10 X 7 X 6 to 19 X 17 X 14 mm. Also the CT scan in idiopathic hyperaldosteronism and glucocorticoid responsive hyperaldosteronism showed bilateral adrenal hyperplasia and bilateral normal adrenal glands, respectively. The pathological findings in these two cases disclosed the adrenal hyperplasia of zona glomerulosa and adrenal hyperplasia of zona subglomerulosa accompanied by a normal thickness of the adrenal gland, respectively. The precision of the CT scan, adrenal scintigraphy and determination of plasma aldosterone in the adrenal or renal veins were almost equal to the diagnosis of the localization of adrenal adenoma. It is concluded that the CT scan is a noninvasive and most useful method for the localization of aldosterone-producing adenoma and helpful in distinguishing adrenal adenoma from adrenal hyperplasia.     

Evaluation of the automatic quantification of left ventricular function using ECG gated 99mTc-MIBI myocardial SPECT

OBJECTIVE: To compare temporal changes in body mass index (BMI) (kg/m2) and prevalence of obesity (BMI > 25 and > 30 kg/m2) among adult Kuwaitis between two periods 14 y apart. DESIGN: Comparison of two independent cross-sectional samples of Kuwaitis studied in 1980-1981 and 1993-1994. SUBJECTS: 2067 (896 men and 1171 women) and 3435 (1730 men and 1705 women) adult Kuwaitis (aged > or = 18 y), drawn from primary health care (PHC) clinics and studied for nutritional assessment and for prevalence of obesity in 1980-1981 and 1993-1994, respectively. MEASUREMENTS: BMI, which is the weight in kilograms divided by the height in meters squared (kg/m2), was based on measured weight and height. Obesity was defined as BMI > 25 kg/m2 (grade 1) and BMI > 30 kg/m2) (grade 2). RESULTS: Mean BMI increased significantly (P < 0.001) by 10.0% and 6.2% (2.5 and 1.7 kg/m2) among men and women, respectively. Prevalence of obesity (BMI > 25 and > 30 kg/m2) increased by 20.6% and 15.4% and by 13.7% and 8.4% among men and women, respectively. After controlling for sociodemographic differences between the two study periods, BMI was 2.0 and 1.6 kg/m2 higher in 1993-1994 than in 1980-1981 among men and women respectively. The risk of obesity (BMI > 25 and > 30 kg/m2) also increased among both genders between the two periods (OR = 2.1, 95% CI 1.7-2.7 and OR = 1.9, 95% CI 1.5-2.4, for men and OR = 2.2, 95% CI 1.6-3.0 and OR = 1.4, 95% CI 2.2 CI-1.0-1.9, for women). CONCLUSION: BMI and prevalence of obesity increased among Kuwaitis between 1980-1981 and 1993 and 1994 probably due to the effects of modernization, affluence, increased food consumption and the concomitant changes to sedentary lifestyles. The rate of temporal changes in BMI and obesity were higher, by comparison, in Kuwait than in selected other countries.     

Effects of thyroid hormone replacement therapy on nocturnal apnea in elderly patients with hypothyroidism

BACKGROUND AND STUDY AIMS: Dieulafoy's disease is a rare cause of upper gastrointestinal tract hemorrhage. The aim of the study was to evaluate the efficacy of endoscopic hemostasis and to analyze the mortality of patients with hemorrhage due to Dieulafoy's disease. PATIENTS AND METHODS: The retrospective analysis included patients from our institution who had undergone urgent endoscopic examination of the upper digestive tract and hemostatic interventions in the period between January 1994 and December 1996. RESULTS: Twenty-five patients were examined (18 men and 7 women, average age 52.6, SD+/-15.3, range 25-78). In 20 patients endoscopic injection sclerotherapy was performed (diluted epinephrine 1:10,000 plus polidocanol 1%) and Nd:YAG laser photocoagulation in five patients. In all patients a total of 44 interventional endoscopies were carried out. Repeated endoscopic hemostasis did not prove successful in two patients (8%, 2 men), and they were treated operatively. During the postoperative period one patient died because of multiorgan failure. The total mortality rate of all patients in which endoscopic hemostasis was done was 16% (4/25). None of the 21 surviving patients had rebleeding on long-term follow-up (mean: 29.4 months). CONCLUSIONS: Endoscopic hemostasis is a major therapeutic advance in the management of Dieulafoy's disease hemorrhage. Interventional endoscopy has decreased the need for surgical management and significantly reduced mortality.