Interface effects on mechanical properties of particle-reinforced composites.

OBJECTIVES: Effective bonding between the filler and matrix components typically improves the mechanical properties of polymer composites containing inorganic fillers. The aim of this study was to test the hypothesis that composite flexural modulus, flexure strength, and toughness are directly proportional to filler-matrix interfacial shear strength. METHODS: The resin matrix component of the experimental composite consisted of a 60:40 blend of BisGMA:TEGDMA. Two levels of photoinitiator components were used: 0.15, and 0.5%. Raman spectroscopy was used to determine degree of cure, and thermogravimetry (TGA) was used to quantify the degree of silane, rubber, or polymer attachment to silica and glass particles. Filler-matrix interfacial shear strengths were measured using a microbond test. Composites containing glass particles with various surface treatments were prepared and the modulus, flexure strength, and fracture toughness of these materials obtained using standard methods. Mechanical properties were measured on dry and soaked specimens. RESULTS: The interfacial strength was greatest for the 5% MPS treated silica, and it increased for polymers prepared with 0.5% initiator compared with 0.15% initiator concentrations. For the mechanical properties measured, the authors found that: (1) the flexural modulus was independent of the type of filler surface treatment, though flexural strength and toughness were highest for the silanated glass; (2) rubber at the interface, whether bonded to the filler and matrix or not, did not improve toughness; (3) less grafting of resin to silanated filler particles was observed when the initiator concentration decreased. SIGNIFICANCE: These findings suggest that increasing the strength of the bond between filler and matrix will not result in improvements in the mechanical properties of particulate-reinforced composites in contrast to fiber-reinforced composites. Also, contraction stresses in the 0.5 vs 0.15% initiator concentration composites may be responsible for increases in interfacial shear strengths, moduli, and flexural strengths.     

Ultrasound evaluation of cervical lymphadenopathy: Can it reduce the need of histopathology/cytopathology?

Background

The differentiation between the causes of cervical lymphadenopathy is of paramount importance as these have different modalities of treatment with varying prognosis. The aim of this study was to evaluate the efficacy of B Mode and colour Doppler ultrasound (CDUS) to differentiate between benign and metastatic lymph nodes.

Cardiovascular complications of chronic renal failure - an updated review

Chronic kidney disease (CKD) is a worldwide public health problem. Cardiovascular disease (CVD) is frequently associated with CKD, which is important because individuals with CKD are more likely to die from CVD than to develop kidney failure. CVD in CKD is treatable and potentially preventable and CKD appears to be a risk factor for CVD. In order of incidence and frequency systemic hypertension, left ventricular failure, congestive cardiac failure, ischemic heart disease, anaemic heart failure, rhythm disturbances, pericarditis with or without effusion, cardiac tamponade, uraemic cardiomyopathy are various cardiovascular complications encountered in patients with chronic renal failure. A patient may present with one or more complications of cardiovascular system. The survival rate and prognosis to a great extent depends on proper management of these complications. Use of regular dialysis and renal transplant has changed the death pattern in developed countries but it is still a major problem in developing country. The aim of this article is early detection of CKD and proper management of it thereby preventing the major cardiovascular complications.     

Thoracic actinomycosis

Thoracic actinomycosis represents about one-fourth of all cases of the disease. Isolated pleural effusion due to Actinomycosis is rare. We report a case of right sided pleural effusion with discharging sinus in the right anterior chest wall. Actinomycosis was suspected and confirmed by microscopic identification of "sulfur granules" in the discharge of the sinus tract and also identification of gram-positive filamentous bacteria in the specimen of discharging sinus. The patient improved clinically and radiologically after treatment with intravenous penicillin G followed by oral penicillin and aspiration of pleural fluid.     

A study of bone mineral density in diabetes mellitus in eastern India

To measure bone mineral density in diabetic patients at the time of clinical diagnosis of diabetes mellitus and to find out correlation, if any, with microvascular complication of diabetes mellitus and glycosylated haemoglobin, a study was conducted at Medical College and Hospital, Kolkata among 138 cases of diabetes and 212 controls. All patients were screened for ophthalmoscopy, routine blood and urine examinations. Bone ultrasound attenuation study of the calcaneus was performed in all cases. The bone ultrasound attenuation result was compared to a mean normal population result and expressed as Z score and T score. The age of diabetic patients varied from 11 years to 70 years. Of 138 diabetics, 32 (23.18%) had type 1 diabetes and rest type 2 diabetes. Forty-two diabetic patients had retinopathy, 42 nephropathy and 48 had neuropathy. Glycosylated haemoglobin was above 7% in 124 patients. The broadband ultrasound attenuation of type 1 diabetics ranged from 38 to 95 dB/MHz and in type 2 it was 35 to 104 dB/MHz. There was no statistically significant correlation between neuropathy, nephropathy, retinopathy and bone mineral density status. It was also found no correlation between glycosylated haemoglobin values and ultrasound attenuation.     

Ultrasonography in Patients with Suspected Acute Appendicitis

Background

To evaluate the usefulness and limitations of graded compression ultrasonography in the diagnosis of clinically equivocal cases of suspected acute appendicitis at the setting of mid zonal military hospital of India.

Methods

A prospective study, graded compression ultrasonography with self localization was carried out with 3.5 MHz convex, 5 MHz convex and 7.5 MHz linear transducers (Wipro GE) in 69 clinically equivocal suspected cases of acute appendicitis. With maximal compression the anteroposterior diameter of appendix was measured from outer to outer wall. The main criterion for diagnosing appendicitis was demonstration of a non compressible appendix with anteroposterior dimension of 7mm or more.

Result

Sonologically 36 (52%) cases were diagnosed as appendicitis. Anteroposterior outer diameter of inflamed appendices ranged from 7mm to 21mm (mean 10.5mm). 30 (83%) of 36 patients could accurately self localize the point of maximum tenderness. There were 01 false positive and 04 false negative cases. Sensitivity and specificity were 89.7% and 96.6% respectively. Positive and negative predictive values were 97.2% and 87.8% respectively. Alternative diagnoses were offered in 33 (47.8%) cases. Amongst these 33 cases, 14(42.4%) had abdominal pain of unknown origin. Gynaecologic, urologic and gastrointestinal aetiologies were established in 10(30.3%), 07(21.2%) and 02(6%) cases respectively.

Conclusion

Graded compression ultrasonography superadded with self localization is an accurate means of diagnosing/excluding appendicitis in clinically equivocal cases of acute appendicitis and it is of great value in establishing alternative diagnoses.Key Words: Ultrasonography, Acute appendicitis     

Transtracheal jet ventilation

Transtracheal jet ventilation (TTJV) is a method of lung ventilation via a narrow-bore catheter placed percutaneously into the trachea, bypassing the upper airway and glottis. A pressurized jet of oxygen that entrains air is delivered to the lungs. This technique can be utilized in both elective and emergency situations. It is no longer recommended by the Difficult Airway Society (DAS) in the ‘Can't Intubate, Can't Oxygenate’ (CICO) situation, as a surgical technique is now recommended in this scenario (unless the practitioner is familiar with TTJV). In the non-CICO emergency situation, TTJV may be utilized to preoxygenate the patient and allow time to secure a definitive airway. Humidified high-flow nasal oxygenation is a more recently described technique that may allow preoxygenation and time for a transtracheal catheter to be placed, and even replace the need for TTJV. However, a jet ventilator should be immediately available in the event of failure of the nasal high-flow system. This article will examine the indications for TTJV and physiology behind its mechanism of action. We will also describe the equipment required, technique and potential complications.     

Primary bilateral tubal adenocarcinoma associated with uterine leiomyomas

Primary adenocarcinoma of the fallopian tube is the least common primary malignant tumor of the female genital tract. Bilaterality is also rare. Often the diagnosis is mistaken for ovarian tumor or tubo-ovarian mass. A case of bilateral primary tubal adenocarcinoma of serous type associated with uterine leiomyomas, without evidence of metastasis occurring in a postmenopausal woman is being reported.