Dielectric Properties of Zeolitic Imidazolate Frameworks in the Broad-Band Infrared Regime.

The field of metal-organic framework (MOF) materials is rapidly advancing toward practical applications; consequently, it is urgent to achieve a better understanding and precise control of their physical properties. Yet, research on the dielectric properties of MOFs is at its infancy, where studies are confined to the static dielectric behavior or lower-frequency response (kHz-MHz) only. Herein, we present the pioneering use of synchrotron-based infrared reflectivity experiments combined with density functional theory (DFT) calculations to accurately determine the dynamic dielectric properties of zeolitic imidazolate frameworks (ZIFs, a topical family of MOFs). We show, for the first time, the frequency-dependent dielectric response of representative ZIF compounds, bridging the near-, mid-, and far-infrared (terahertz, THz) broad-band frequencies. We establish the structure-property relations as a function of framework porosity and structural change. Our comprehensive results will pave the way for novel ZIF-based terahertz applications, such as infrared optical sensors and high-speed wireless communications.

Prevalence and associated risk factors of male erectile dysfunction among patients on hemodialysis and kidney transplant recipients: a cross-sectional survey from Sudan.

Male erectile dysfunction (ED) is an important issue worldwide occurring in 5-69% of men in community-based studies. It is more common in patients with chronic kidney disease (CKD) and those on peritoneal as well as hemodialysis (HD), occurring in more than 80% of patients. In Sudan, there is no previous report on ED among patients with CKD. A cross-sectional study was done to determine the prevalence of ED and its associated risk factors among Sudanese CKD patients on HD and those who underwent renal transplant. This was conducted in Khartoum, Sudan from October 2005 to July 2006 including all married men who were on maintenance HD for more than three months and all married men who had received renal transplantation at least three months earlier. Single, divorced/separated men, those whose wives were living away, those who were bed-bound and those with cognitive impairment were also excluded. After obtaining consent for participation, demographic and clinical data were collected by using anonymous questionnaires and the Arabic version of International Index of Erectile Function (IIEF; the Egyptian version). Patients who did not participate in full and proper manner were considered as "non-responders." A total of 146 patients, 106 HD patients, and 40 renal transplant recipients completed the IIEF questionnaire. Non-responders constituted 43.7% and 54.5% of HD and transplant recipient patients, respectively. Blood samples were taken after completion of the IIEF questionnaire to determine the required investigations. ED prevalence was high among our study patients, 83% among the HD patients and 67.5% among the renal transplant recipients. Univariate analysis showed that there was a trend, although non-significant, of older age being associated with ED in both groups. Similar association was seen in those who were under-dialyzed in the HD group and DM in the transplant recipient group. Previous history of ED was significantly associated with current presence of ED in both groups. More studies with larger sample size are needed to clarify the results of this study.

Thyroid function in patients with mycetoma.

Thyroid function was assessed in seventy two patients with various types of mycetoma. There was no evidence of clinical or biochemical thyroid dysfunction in these patients. The symptoms encountered in some of the mycetoma patients mimic those of hypothyroidism should be attributed to other factors possibly mental depression and apathy.

Pattern of diabetes mellitus in the Sudan.

448 Sudanese diabetics were included in this study. 30% of patients were in the age group 40-50 years and only 6.3% had childhood diabetes. The predominant sex was female (64.5%). Obesity was found in 39% of patients, a positive family history in 66.5% and a history of diabetic ketoacidosis in 25.2%. 100 patients (below the age of 40) had a plain X-ray abdomen done but none had evidence of pancreatic calcification. Percentages of diabetic complications in this study were as follows: neuropathy 28.1%, retinopathy 18.5%, cataract 14.7%, hypertension 12.9%, nephropathy 11.6%, peripheral vascular disease 6.2%, coronary heart disease 4.2% and pulmonary tuberculosis 2.7%. The majority of our patients were uncontrolled, only 16.7% had normoglycaemia (FBG less than 140 mg%).

Glycated haemoglobin and other biochemical parameters in Sudanese diabetics.

Fasting levels of glycated haemoglobin, cholesterol and triglycerides were studied in 44 patients with non-insulin-dependent diabetes mellitus (NIDDM), 31 patients with insulin-dependent diabetes mellitus (IDDM) and 28 healthy Sudanese individuals. Results confirmed previous observations showing correlation of glycated haemoglobin with fasting blood glucose in NIDDM (r = 0.634; P less than 0.001), and with cholesterol in IDDM (r = 0.355; P less than 0.05). No correlation of glycated haemoglobin with triglycerides was observed in either group of diabetics. A negative correlation was demonstrated between glycated haemoglobin and the duration of diabetes (r = -0.552; P less than 0.01) in IDDM. It seemed that control improved in these patients as their diabetes progressed, probably through self-education.