An Ultrasonic Evaluation and Quality Control Tool for Adhesive Bonds

The problem of predicting adhesive bond performance for both surface preparation and undercure defects has been studied using an ultrasonic, experimental test bed system. This experimental test bed incorporates the ultrasonic and computer equipment necessary to acquire and process data from various types of adhesively bonded test specimens. The computer hardware and software has been developed to allow the design of reliable pattern recognition algorithms for the evaluation of surface preparation and bond cure. The specific problem studied is the inspection of the adhesive bond in an aluminum to aluminum step-lap joint whose strength could be affected by improper surface preparation or undercure. A set of 154 bond specimens was used to design an algorithm that is 91% reliable for separating the specimens into a good class, those bonds with no defects, or a weak class, bonds with poor surface preparation or undercured adhesive layer. A Fisher Linear Discriminant function was selected by the test bed as the best pattern recognition routine for this classification problem.     

Access to Pediatric Neurologists - Will Telemedicine Close the Gap?

Many times both physicians and patients take for granted that they are qualified to treat certain ages and certain conditions. Neurological conditions are diagnosed and treated by neurologists, pediatric neurologists, and neurosurgeons. What is the difference and why does it matter? It is a balancing act of risk and benefit and the physician’s obligation to know her/his limitations. Telemedicine may play a key role in enabling a greater access to pediatric neurologists. If telemedicine becomes more available, then access even in more remote areas without child neurologists may be possible. As this article discusses, there may be certain limitations to using telemedicine, which is distinguishable from telehealth, in relation to pediatric neurology. This article examines the type of neurological physician that is the most appropriate; the availability of and access to pediatric neurologists; and the applicability of telemedicine to the diagnosis and treatment of pediatric neurological conditions.     

A fracture criterion for nuclear graphite

Measurements of tensile and flexural strength of a nuclear graphite using small bar specimens are reported. A theoretical model of failure is described in which critical defects are assumed to be associated with cleaved large coke particles. It is further assumed that these subcritical cracks can only extend by the cleavage of small particles which surround them. The size of the critical flaws is defined on the basis of linear elastic fracture mechanics. The model predicts the observed variation in flexural strength in three- and four-point bending as the knife edge spacings are varied. It slightly overestimates the observed ratio of tensile-to-bend strength, and this is thought to be due to some of the simplifying assumptions made in the models formulation. The potential of the model for use in engineering applications is discussed.     

Radon and moisture impacts from interventions integrated with housing energy retrofits

Energy retrofits can reduce air exchange, raising the concern of whether indoor radon and moisture levels could increase. This pre/post-intervention study explored whether simple radon interventions implemented in conjunction with energy retrofits can prevent increases in radon and moisture levels. Treatment homes (n = 98) were matched with control (no energy retrofits or radon intervention) homes (n = 12). Control homes were matched by geographic location and foundation type. t-tests were used to determine whether post-energy retrofit radon and moisture level changes in treatment homes significantly differed from those in control homes. The radon interventions succeeded in preventing statistically significant increases in first floor radon using arithmetic (p = 0.749) and geometric means (p = 0.120). In basements, arithmetic (p = 0.060) and geometric (p = 0.092) mean radon levels statistically significantly increased, consistent with previous studies which found that basement radon levels may increase even if first floor levels remain unchanged. Changes in infiltration were related to changes in radon (p = 0.057 in basements; p = 0.066 on first floors). Only 58% of the change in infiltration was due to air sealing, with the rest due to weather changes. There was no statistically significant association between air sealing itself and radon levels on the first floor (p = 0.664). Moisture levels also did not significantly increase.     

Making the invisible visible: Fear and disclosure of sexual orientation at work.

Stigma theory was used to examine the fears underlying the disclosure of a gay identity at work. Using a national sample of 534 gay, lesbian, and bisexual employees, this study examined the antecedents that affect the degree of disclosure of a gay identity at work and, for those who had not disclosed, the factors that influence their fears about full disclosure. Employees reported less fear and more disclosure when they worked in a group that was perceived as supportive and sharing their stigma. Perceptions of past experience with sexual orientation discrimination were related to increased fears but to greater disclosure. For those who had not fully disclosed their stigma, the fears associated with disclosure predicted job attitudes, psychological strain, work environment, and career outcomes. However, actual disclosure was unrelated to these variables. The utility of fear of disclosure for understanding processes underlying the disclosure of gay and other invisible stigmatized identities in the workplace is discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Environmental tobacco smoke exposure and health effects in children: results from the 1991 National Health Interview Survey

PURPOSE: There is no consensus in the literature regarding the role of lymphangiography in promoting hypothyroidism in individuals with Hodgkin's disease irradiated with a mantle field. We sought to analyze the onset and rate of developing clinical or chemical hypothyroidism as well as possible factors related to its development in patients who received irradiation to the thyroid gland during treatment of Hodgkin's disease. METHODS AND MATERIALS: One hundred and forty-two patients with Hodgkin's disease were treated at the Fox Chase Cancer Center between June 1967 and October 1993. All patients were treated with curative intent with radiation therapy using a mantle field. After exclusion of patients without available thyroid function tests, < 200 days of follow-up, or no radiation to the thyroid, 104 patients were eligible for analysis. Follow-up ranged from 7-170 months (median: 43 months). Sixty-seven patients had a lymphangiogram. Seventy-three patients were treated with radiation alone and 31 with radiation plus chemotherapy. RESULTS: The actuarial 2-, and 5-year rates of biochemical hypothyroidism for all 104 patients were 18 and 37%, respectively. Forty patients developed hypothyroidism: 9 (23%) at < or = 1 year, 18 (45%) at < or = 2 years, and 33 (83%) at < or = 5 years. The actuarial 2-, and 5-year rates of biochemical hypothyroidism for patients who underwent a lymphangiogram were 23 and 42%, respectively, compared to 9 and 28%, respectively, for patients who received mantle irradiation without a lymphangiogram (p = 0.05). The effects of lymphangiogram, total thyroid dose, stage, chemotherapy, dose per fraction, energy, and age were evaluated for all patients by Cox proportional hazards regression analysis. The use of a lymphangiogram (p = 0.05) was the only variable that significantly influenced hypothyroidism. CONCLUSIONS: This paper demonstrates in a multivariate analysis accounting for other potentially important variables the significant effect of lymphangiography and subsequent radiation therapy on the development of hypothyroidism. This information must be balanced with the fact that lymphangiograms remain a useful aid in assessing lymph node involvement, staging patients, and planning treatment fields.     

Management of bronchobiliary fistula as a late complication of hepatic resection

Bronchobiliary fistula is an uncommon but remarkable complication after hepatic resection. The case reported illustrates the clinical presentation and preferred initial management of these fistulae. A 61-year-old white male underwent two wedge resections for colorectal metastases to the liver with removal of a portion of the right diaphragm. Four years later, he developed obstructive jaundice secondary to tumor recurrence in the porta hepatis, which required endoscopic stent placement, radiation, and chemotherapy. Almost 2 years later, he developed frank biliptysis. Percutaneous transhepatic cholangiography (PTC) revealed occlusion of the common hepatic duct stent and a bronchobiliary fistula. With adequate reestablishment of common duct drainage, the patient rapidly improved and was discharged free of symptoms. Bronchobiliary fistulae are rare complications of hepatic resection that can present from days to years after operation. Endoscopic retrograde cholangiopancreatography and PTC are the diagnostic studies of choice and offer the possibility of therapeutic intervention. Although large series in the literature emphasize the surgical management of bronchobiliary fistulae, the reoperative procedures tend to be complicated, with a significant morbidity and mortality. Nonsurgical interventions via endoscopic retrograde cholangiopancreatography or PTC are more recently notably successful when resolution of a distal biliary obstruction is accomplished. Only after aggressive attempts at nonoperative, interventional techniques have failed should operative approaches be entertained.     

Sparking Nano-Metals on a Surface of Polyethylene Terephthalate and Its Application: Anti-Coronavirus and Anti-Fogging Properties

The nano-metal-treated PET films with anti-virus and anti-fogging ability were developed using sparking nano-metal particles of Ag, Zn, and Ti wires on polyethylene terephthalate (PET) films. Ag nanoparticles were detected on the PET surface, while a continuous aggregate morphology was observed with Zn and Ti sparking. The color of the Ag-PET films changed to brown with increasing repeat sparking times, but not with the Zn-PET and Ti-PET films. The water contact angle of the nano-metal-treated PET films decreased with increasing repeat sparking times. The RT-PCR anti-virus test confirmed the high anti-virus efficiency of the nano-metal-treated PET films due to the fine particle distribution, high polarity, and binding of the nano-metal ions to the coronavirus, which was destroyed by heat after UV irradiation. A highly transparent, anti-fogging, and anti-virus face shield was prepared using the Zn-PET film. Sparking was an effective technique to prepare the alternative anti-virus and anti-fogging films for medical biomaterial applications because of their low cost, convenience, and fast processing.     

Ultrahigh molecular weight polyethylene as used in articular prostheses (a molecular weight distribution study)

Currently there is widespread use of ultrahigh molecular weight polyethylene (UHMWPE) acetabular components in total joint replacement prostheses. What has been most surprising about the wear of UHMWPE under such circumstances is the occurrence of brittle fracture. Such fracture had not been observed in the usual engineering tests done in the laboratory on UHMWPE. It was only when prosthese which had been removed from patients were examined or run in hip joint simulators with serum or synovial fluid as the lubricant, that brittle fracture was encountered. The problem of environment-enhanced brittle fracture in plastics dates back to 1946. Interestingly, the phenomenon was first described in polyethylene. The prime variables involved are polymer molecular weight, sensitizing environment, stress filed, and temperature. Other things being equal, brittle behavior in polyethylene is extremely sensitive to the amount of low molecular weight polymer present. In the light of the foregoing we have studied the molecular weight distribution in six commercially available UHMWPE components. These were obtained from six different manufacturers. The specimens were characterized both on their bearing (wear) surfaces and in their interior bulk. The results obtained indicate that:

• 1 The UHMWPE components contain substantial amounts of low molecular weight polymer.
• 2 The UHMWPE components differ significantly in molecular weight distribution.
• 3 The UHMWPE components contain substantial amounts of crosslinked polymer.

     

Interactions between immunoglobulin-like and catalytic modules in Clostridium thermocellum cellulosomal cellobiohydrolase CbhA

Cellobiohydrolase CbhA from Clostridium thermocellum cellulosome is a multi-modular protein composed starting from the N-terminus of a carbohydrate-binding module (CBM) of family 4, an immunoglobulin(Ig)-like module, a catalytic module of family 9 glycoside hydrolases (GH9), X1(1) and X1(2) modules, a CBM of family 3 and a dockerin module. Deletion of the Ig-like module from the Ig-GH9 construct results in complete inactivation of the GH9 module. The crystal structure of the Ig-GH9 module pair reveals the existence of an extensive module interface composed of over 40 amino acid residues of both modules and maintained through a large number of hydrophilic and hydrophobic interactions. To investigate the importance of these interactions between the two modules, we compared the secondary and tertiary structures and thermostabilities of the individual Ig-like and GH9 modules and the Ig-GH9 module pair using both circular dichroism (CD) spectroscopy and differential scanning calorimetry (DSC). Thr230, Asp262 and Asp264 of the Ig-like module are located in the module interface of the Ig-GH9 module pair and are suggested to be important in 'communication' between the modules. These residues were mutated to alanyl residues. The structure, stability and catalytic properties of the native Ig-GH9 and its D264A and T230A/D262A mutants were compared. The results indicate that despite being able to fold relatively independently, the Ig-like and GH9 modules interact and these interactions affect the final fold and stability of each module. Mutations of one or two amino acid residues lead to destabilization and change of the mechanism of thermal unfolding of the polypeptides. The enzymatic properties of native Ig-GH9, D264A and T230A/D262A mutants are similar. The results indicate that inactivation of the GH9 module occurs as a result of multiple structural disturbances finally affecting the topology of the catalytic center.