Solitary Rectal Ulcer Syndrome in Patients Presenting With Lower Gastrointestinal Bleeding: A Tertiary-Care Hospital Experience.

BACKGROUND: Solitary rectal ulcer syndrome (SRUS) is a benign rectal condition associated with defecation disorder that has multifactor pathologies and variable findings on presentation, endoscopy, and histopathology. A diagnostic dilemma with an overlap of differentials and step-wise management that starts with conservative therapies and goes up to repeated surgeries in case of failure of the conservative approach. OBJECTIVE: This study aims to observe clinical, endoscopic, and histological features of SRUS in patients presenting with lower gastrointestinal bleeding. MATERIAL AND METHODS: The study was conducted at the Department of Gastroenterology, Medical Teaching Institute, Lady Reading Hospital Peshawar from October 2018 to April 2020. After written informed consent, 257 patients (149 males and 108 females) from ages 15 to 70 who presented with lower GI bleeding were included via non-probability convenient sampling. Sociodemographic details were recorded in a pre-designed proforma. A colonoscopy was performed with the Colonoscope CF200 Z, Olympus Tokyo, Japan, and findings were noted. Suspected lesions were magnified, dyed with 0.2% indigo carmine, biopsied from the middle and edges of the ulcer, and sent for histopathology. All data were recorded and analyzed in SPSS-20. The mean with SD was calculated for quantitative variables, and frequency and percentages were calculated for qualitative variables. The chi-square test was used to check the significance, and a p-value of <0.05 was considered statistically significant. RESULTS: SRUS was found in 17 (6.6%) patients with lower GI bleeding, with a male predominance of 57% (n=11). Perirectal bleeding, constipation, mucous discharge, abdominal pain, and anemia were common clinical findings. Solitary lesions, ulceration, and anterior rectum location were the most common endoscopy findings. Obliterated lamina propria with collagen, ulceration, crypt distortion, and inflammatory infiltrates were common histopathological findings. CONCLUSION: SRUS is a benign defecation disorder commonly presenting with lower GI bleeding, constipation, straining, and abdominal pain. It needs a stepwise approach with conservative management, medical management, biofeedback, and surgeries as a last resort.

NEUTRON GENERATOR FACILITY AT SFU: GEANT4 DOSE RATE PREDICTION AND VERIFICATION.

Detailed dose rate maps for a neutron generator facility at Simon Fraser University were produced via the GEANT4 Monte Carlo framework. Predicted neutron dose rates throughout the facility were compared with radiation survey measurements made during the facility commissioning process. When accounting for thermal neutrons, the prediction and measurement agree within a factor of 2 or better in most survey locations, and within 10 % inside the vault housing the neutron generator.

Cleaving the Halqeh-ye-nur diamonds: a dynamic fracture analysis.

The degree of surface roughness and clarity with which a surface in a brittle material can be formed via fracture is known to be related to the speed of the propagating crack. Cracks traversing a brittle material at low speed produce very smooth surfaces, while those propagating faster create less reflective and rough surfaces (Buehler MJ, Gao H. 2006 Nature 439, 307-310 (doi:10.1038/nature04408)). The elastic wave speeds (c(l)≈18 000 m s(-1), c(s)≈11 750 m s(-1)) in diamond are fast (Willmott GR, Field JE. 2006 Phil. Mag. 86, 4305-4318 (doi:10.1080/14786430500482336)) and present a particular problem in creating smooth surfaces during the cleaving of diamond-a routine operation in the fashioning of diamonds for gemstone purposes--as the waves are reflected from the boundaries of the material and can add a tensile component to the propagating crack tip causing the well-known cleavage steps observed on diamond surfaces (Field JE. 1971 Contemp. Phys. 12, 1-31 (doi:10.1080/00107517108205103); Field JE. 1979 Properties of diamond, 1st edn, Academic Press; Wilks EM. 1958 Phil. Mag. 3, 1074-1080 (doi:10.1080/14786435808237036)). Here we report an analysis of two diamonds, having large dimensions and high aspect ratio, which from a gemological analysis are shown to have been cleaved from the same 200 carat specimen. A methodology for their manufacture is calculated by an analysis of a model problem. This takes into account the effect of multiple reflections from the sample boundaries. It is suggested that the lapidary had an intuitive guide to how to apply the cleavage force in order to control the crack speed. In particular, it is shown that it is likely that this technique caused the fracture to propagate at a lower speed. The sacrifice of a large diamond with the intention of creating thin plates, rather than a faceted gemstone, demonstrates how symbolism and beliefs associated with gemstones have changed over the centuries (Harlow GE. 1998 The nature of diamonds, Cambridge University Press). The scientific insights gained by studying these gemstones suggest a method of producing macroscale atomically flat and stress-free surfaces on other brittle materials.

Chronic inflammatory demyelinating polyradiculoneuropathy in diabetic patients.

This retrospective analysis was undertaken to determine whether a subset of diabetic patients with demyelinating polyneuropathy were similar to patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Ten patients meeting the clinical criteria for idiopathic CIDP were compared to nine patients with diabetes and demyelinating polyneuropathy. The diabetic patients with demyelinating polyneuropathy displayed clinical, electrophysiologic, and histologic features that were similar to those in CIDP patients. All six patients with diabetes and demyelinating polyneuropathy who were treated with immunomodulatory therapy showed a favorable response. Our study highlights the importance of investigating diabetic patients with polyneuropathy in an attempt to identify patients with demyelinating polyneuropathy, because of the likelihood of benefit in these patients from immunomodulatory treatment.

Large-area synthesis of carbon nanofibres at room temperature.

Carbon nanotubes, first identified by Iijima, require for their production a source of elemental carbon and a transfer of energy that is specific to the type of source and the growth environment. Methods developed so far involve arc discharge, and vaporization using laser, pyrolysis and chemical vapour deposition of hydrocarbons. Here, we show growth of carbon nanofibres from radio-frequency plasma-enhanced chemical vapour deposition at room temperature, which was made possible by substituting the thermal energy requirements for the growth with plasma decomposition of methane on the Ni catalyst. Electron microscopy analysis provides evidence for a 'tip' growth model, with the Ni catalyst particle attached to the tip of the nanofibre. Energy-filtered imaging shows the Ni catalyst has a surface layer rich in carbon, consistent with the formation of a eutectic Ni-C droplet as a nucleation site for the carbon nanofibres, so that the carbon diffuses across the surface. The reduced distortion of the catalyst particles at low temperatures leads to a more uniform growth of the carbon nanofibres over large areas. The lower growth temperature allows for the removal of the silicon dioxide barrier layer associated with catalytic growth, and should allow in situ growth of nanofibres on relatively large areas of temperature-sensitive substrates, such as plastics, organics and even paper.