[en] Collisions of slow molecular ions with surfaces is a research area growing rapidly during the last decade in an effort to identify and explore new methods for characterizing both molecular ions and the nature of surfaces. As slow ions one usually regards hyperthermal ions of energies about 0-100 eV. In this energy regime the energy transfer from collisional to internal modes of a molecule is of the same order of magnitude or somewhat larger than chemical bond energies. The energy transfer in ion-surface interaction is thus large enough to lead to bond dissociation and yet not too large to obscure the chemical nature of it. Surface induced dissociation is very useful for structural analysis of molecular as well as cluster ions and has been established as an important tool in mass spectrometry. Other processes of interest here are chemical sputtering, which gives information about the nature of the surface as well as charge changing reactions. Chemical reactions of ions with surfaces are the most interesting but least understood processes in the field of ion surface interactions. The chemical reactions occurring upon impact of different species on target surfaces are highly specific to the projectile ion/surface combination and can form the basis for many technological applications. In the present work for the first time we systematically investigated the surface induced dissociation of diatomic (H₂⁺, D₂⁺ and HD⁺) and triatomic (H₃⁺, D₃⁺ and HD₂⁺) molecular hydrogen and deuterium ions upon impact on a graphite tile from the tokamak experiment TORE SUPRA in CEA-Cadarache/France and a stainless steel surface. Several trends can be deduced from the experimental results: (1) Both, the diatomic and the triatomic hydrogen (deuterium) molecular ion almost exclusively fragment into the atomic ion. (2) With increasing collision energy the ion yield of intact scattered projectile ions decreases faster for hydrogen compared to deuterium in all cases concerning both, target material and molecular size. (3) At high collision energies the fragment ion yield for D₂⁺ and D₃⁺ compared to their H containing counterparts is larger when hitting stainless steel but lower for a graphite target. (4) In all cases the atomic fragment ion reaches 50 % of its maximum intensity at higher energies when going from hydrogen to deuterium and from diatomic to triatomic projectile ions. A comparison between the results obtained with hydrogen and deuterium suggests that the fragmentation of the molecular ions is driven by an electronic process where resonant electron transfer from the surface into an anti-bonding orbital of the neutralized molecule drives the atoms apart. The results showed that on the average hydrocarbon ions produced in the Nier-type ion source have -1 eV higher internal energy as compared to the ions produced in the Colutron ion source. The hydrocarbon projectile ions C₂H₄⁺ produced in the Nier-type ion source by electron impact of ethylene have about 0.3 eV less internal energy content as compared to the same ion when it was produced from ethane in the same ion source. The present results clearly demonstrate the importance of internal energy content of the projectile ions on their surface induced dissociation dynamics. The last chapter of the thesis deals with reactive interaction of a biomolecule, i.e., the formic acid ion HCOOH⁺ and its fragment ion HCOO⁺ with a stainless steel surface. The three most abundant unimolecular dissociation channels of HCOOH⁺ are identified as HCOOH⁺ HC00⁺ + H, HCOOH⁺ HCO⁺ + OH and HCOOH⁺ H₂0⁺ + CO. Moreover I have detected the protonated formic acid ion H₂COOH⁺ produced by reaction of the projectile ion HCOOH⁺ with surface adsorbates. The hydrocarboxyl radical cations H000⁺ decomposes after surface impact only into HCO⁺ + O. The observed dissociation pattern of the HCOOH⁺ projectile ion is compared with available ab initio molecular orbital calculations. (author)

[en] Objective of the study was to evaluate the diagnostic yield of X-rays taking CT scan as gold standard in acute and chronic sinusitis. Study Design: Validation study. Place and Duration of study: The study was conducted in the Radiology Department CMH Rawalpindi, from 1 Aug, 2007 to 31 July, 2008. Patients and Methods: This study involved 95 patients of both genders above 18 years of age who presented with acute and chronic sinusitis in ENT department of CMH Rawalpindi. Patients were referred to Radiology department for their X-ray paranasal sinuses (PNS) and findings were correlated with CT scan. Results: Out of 43 patients clinically suspected of having acute sinusitis, x ray PNS shows imaging findings of acute sinusitis in 26 (60%) patients while 17 patients were having normal x-ray PNS. When CT scan was performed to correlate the findings, it showed 30 (69%) patients were having acute sinusitis while 13 (30%) patients had no imaging findings of sinusitis. Out of 48 patients, X ray PNS showed chronic sinusitis in 26 (54%) patients and 22 patients were having normal x ray PNS. While CT scan showed 33 (68%) patients were having chronic sinusitis and 15 patients were normal. Four patients either didn't reported for their CT scan or they refused to get their CT scan done. Conclusion: Plain radiographs were once the mainstay of diagnosis of sinus disease and now have been replaced by high-resolution CT scan for the evaluation of acute and chronic sinusitis. Plain radiographs do not allow adequate evaluation of the osteomeatal complex or of the sphenoid and ethmoid sinuses because of overlapping anatomic structures. CT is the modality of choice for imaging acute and chronic sinusitis and provides the surgeon with important information of the osteomeatal complex and normal variations, preoperatively. (author)

[en] Objective: The objective of the study was to determine the role of various known risk factors for the development of Transitional cell carcinoma (TCC) of urinary bladder in our set up. Study design: Case control study Place and duration of the study: Department of Radiology CMH Rawalpindi, from March 2007 to December 2007. Material and methods: 70 patients with TCC urinary bladder were included in the study. 70 controls were included. The patients were enquired about the risk factors. The data was analysed on SPSS version 12. Odds ratio for each factor was carried out. p value of < 0.05 was considered statistically significant. Results: Smoking was the most important factor in the development of TCC of urinary bladder with odds ratio of 3:1. Driving was the next common factor. Low socioeconomic conditions appear to be an important factor in our set up. The role of chemicals in industrial work could not be established. Conclusion: Differences from the West exist regarding the etiological factors for the development of TCC of urinary bladder. Males outnumber the females by a significant ratio. Smoking is an important factor in the development of TCC of urinary bladder. Most bladder cancers arise in low socioeconomic group in our set up. (author)

[en] Objective: To observe trends of gynaecological malignancies at Combined Military Hospital Lahore. Study Design: Cross-sectional study. Place and Duration of Study: Combined Military Hospital Lahore Pakistan, from Jan 2015 to Dec 2019. Methodology: Data was retrieved from patient admission and discharge notes and their records at the pathology department. Variables like trends of gynaecological malignancies, mean age, common presenting complaint, and common malignancy with histopathology type were collected. Results: A total of 107 patients were selected from 2015-2019. Commonest malignancy observed was carcinoma endometrium 51 (47.6%) followed by carcinoma ovary 32 (29.9%), and gestational trophoblastic disease 17 (15.8%), carcinoma cervix 6(5.6%) with one case of carcinoma vulva (0.9%). The common presentation was postmenopausal bleeding 27 (25.2%). Among endometrial carcinoma, adenocarcinoma was the common histopathological type (92.1%). The mean age observed with carcinoma endometrium was 46.9±9 years, ranging from 45-65 years. Conclusion: Endometrial malignancy was the commonest malignancy observed in our study. Most patients presented with postmenopausal bleeding. Trends of different gynaecological malignancies were reviewed. (author)

[en] An ExB velocity filter is described that has been used for the detection and diagnostics of large carbon clusters C_m (m≤10⁴). The velocity and momentum analyses are compared for our special experimental arrangement. We describe the variability of the resolving power of our compact velocity filter as the main advantage over other comparable mass analysis techniques

[en] Objective: To compare ultrasonography (US) and computed tomography (CT) data for evaluation of abdominal aortic aneurysm. Study Design: Validation study. Place and Duration of Study: Radiology Department Combined Military Hospital Rawalpindi, from Apr 2006 to Jan 2008. Material and Methods: This study involved 67 patients. Both ultrasonography and computed tomography were performed on each patient for evaluation of different variables of abdominal aortic aneurysm. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy and p-values were calculated for all qualitative variables separately. Mean and standard deviation (SD) were calculated for the quantitative variables. Results: Ultrasound measurements of abdominal aortic aneurysm were both accurate and reproducible. The sensitivity and specificity of ultrasonography for abdominal aortic aneurysm were >90% for all attributes, with minor differences usually resulting from measurement variation rather than failure to distinguish between large aneurysms and normal aortas. Conclusion: Ultrasound was equally effective in comparison with computed tomography not only in diagnosing abdominal aortic aneurysm but also in assessing its different attributes. (author)

[en] Photoemission spectroscopy of the regenerative soot in neon's glow discharge plasma reveals the contributions from the sputtered atomic and molecular carbon species. We present the pattern of sputtering and the formation of monoatomic C₁ and diatomic C₂ as a function of the discharge current, the support gas pressure and the number densities of the excited and ionized neon as the active constituents of the carbonaceous plasma

[en] To determine the frequency of different disorders requiring warfarin therapy and to see the target INR and warfarin dose requirement in Pakistani population. Study Design:Descriptive study. Setting and Duration of Study: The study was carried out at Armed Forces Institut e of Cardiology (AFIC) Rawalpindi, Military Hospital Rawalpindi and National Institute of Cardiovascular Diseases (NICVD), Karachi, Pakistan from October 2010 to March 2012. Patients and Methods: Stable patients taking warfarin therapy were recruited after detailed medical history, physical examination and laboratory tests. The demographic and clinical data of individuals were entered in a pre-structured proforma. Patients suffering from hepatic and renal disease, any co-morbid disease or taking any concurrent medication or diet which would have affected warfarin therapy, were excluded. Data was analyzed using PSS version 20.0. Results: A total of 607 stable patients fulfilling the eligibility criteria, participated in the study. There were 297 (48.9%) male and 310 (51.1%) female patients. The mean age was 37.93 +- 12.23 years (range 18-65 years). The most common indication for warfarin therapy was valvular heart diseases (93.4%) followed by atrial fibrillation (2.3%) whereas other indications for warfarin use are less commonly seen in our study population. Patients had mean international normalized ratio (INR) value of 2.3 +9- 0.8 (range 1.5-3.5). Mean daily dose of warfarin calculated in 607 patients was 5.62 and 1.98 mg with the range of 0.36-15 g whereas mean weekly dose was 39.36 +- 13.8 mg with the range of 2.5-105 mg. Conclusion: In Pakistani population the most common indications for warfarin use are valvular heart diseases followed by atrial fibrillation. The mean INR values were within recommended range of 2-3. The mean daily dose observed in long-term therapy is comparable to the empirical dose of 5 mg routinely started in clinical practice. (author)

No abstract available

[en] Photon emission originating from sputtering of a polycrystalline aluminum surface under 1-10 keV ion (H⁺, He⁺, Ar⁺, Kr⁺ and Xe⁺) bombardment has been studied. Measured photon emission yields from the 3d ²D_3/2 resonance transition of sputtered excited Al atoms and calculated nuclear stopping powers are compared. The results demonstrate that elastic collisions play a major role in photon emission. Moreover, measurements of photon intensity as a function of the distance from the target surface show that decays of sputtered excited ions Al⁺ and Al²⁺ are faster than decays of excited Al atoms, and less affected by cascade repopulation and de-excitation of fast ions