Synthesis, Optical, Thermal and Structural Characteristics of Novel Thermocleavable Polymers Based on Phthalate Esters.

In this work three novel phthalate-based thermocleavable copolymers, PBTP-11, PBTDTP-11 and PFDTP-11 have been designed and synthesized. PBTP-11 and PBTDTP-11 were prepared by copolymerizing distannylated bithiophene without or with flanked thienyl groups as the electron-donor units with dibrominated secondary phthalate ester as the electron-acceptor units. PFDTP-11 was prepared by copolymerizing distannylated fluorene flanked by thienyl groups as the electron-donor moieties with dibrominated secondary phthalate ester as the electron-acceptor moieties. All polymers were prepared via the Stille polymerization. The impact of two different electron-donor units on the solubility, molecular weights, optical properties, thermal and structural properties of the resulting polymers were investigated. PFDTP-11 had the highest average molecular weight (Mn = 16,400 g mol-1). The polymers had Eg in the range of 2.11-2.58 eV. After thermal treatment, the Eg of the polymers were reduced by around 0.3-0.4 eV. This significant control over bandgap is promising and opens a gate towards commercializing these copolymers in energy harvesting devices such as solar cells. TGA data showed weight loss at around 300 °C, corresponding to the elimination of the secondary ester groups. After annealing, the soluble precursor polymers were transformed into active phthalic anhydride polymers and the resulting films were completely insoluble in all solvents, which shows good stability. Powder XRD studies showed that all polymers have an amorphous nature in the solid state, and therefore can be employed as electrolytes in energy devices.

Theoretical investigations on the electronic and optical properties of bridged oligothiophenes.

A study of the structure, electronic, and optical properties of oligothiophenes is reported. Geometry optimizations of the ground state of derivatives of these molecules were carried out using the density functional theory (DFT) with the B3LYP functional and the 6-31G(d) basis set. Bridged oligothiophenes by C═O, C═S, and C═C(CN)(2) functional groups were found to be planar in their electronic ground states (S(0)). The electronic excitation transitions of the bridged oligothiophenes were investigated using the time-dependent TD-DFT method performed on the ground-state optimized geometries. For all the derivatives, excitation to the S(1) state corresponds mainly to the HOMO → LUMO transition. The excitation energies are found in fair agreement with the experimental values. The optimization (relaxation) of the first singlet excited electronic state (S(1)) has been done using the restricted configuration interaction (singles) (RCIS/6-31G(d) approach. The electronically excited geometries favor a more quinoidic type structure. Emission energies have been obtained from TD-DFT calculations performed on the excited-state optimized geometries S(1). The change of group (C═O, C═S, and C═C(CN)(2)) as well as the incorporation of monomer moieties induce a significant decrease in the excitation and emission energies.

Role of magnetic resonance imaging in evaluation of tubercular spondylitis: pattern of disease in 100 patients with review of literature.

INTRODUCTION: The purpose of this study is to evaluate the role of magnetic resonance imaging (MRI) in evaluation of tubercular spondylitis and to correlate imaging findings with clinical severity of the disease. METHODS: One hundred consecutive patients, who presented with features suggestive of spinal infections, were subjected to MRI examination. T1W and STIR images were obtained followed by T2W and post-contrast T1W images. Various imaging characteristics of spinal infections were noted and correlated with the clinical severity of the disease. RESULTS: Backache was the most common presenting symptom present in 86 %, while paraparesis was the most common sign seen in 62 %. The neurological status of the patients correlated well with MRI findings in the majority of the cases with an overall good correlation obtained in 96 % of cases. The majority of the vertebrae and intervertebral discs affected showed hypointensity or isointensity on T1W images and hyperintensity on T2W images. Epidural/dural disease was present in 74 % while 68 % of patients demonstrated decreased intervertebral disc height. Epidural extension and subligamentous spread was in 74 % and 90 % of patients respectively. CONCLUSIONS: MRI plays a vital role in early and accurate diagnosis of spinal infections. It is non-invasive and clearly demonstrates soft tissue anatomy and pathology which makes it superior to X-rays and Computed Tomography (CT). Imaging findings of tubercular spondylitis were also found to have a good correlation with the clinical status of the patients. Hence, it is of much help in the evaluation and assessment of patients presenting with features of spinal infections.

Single molecule spectroscopy of red- and green-emitting fluorene-based copolymers.

Single molecule fluorescence spectroscopy is used to study the optical properties of two polymers: a fluorene-based statistical copolymer that contains a low fraction (10%) of a red-emitting thiophene group, and the green-emitting polymer poly(9,9-dioctylfluorene-alt-benzothiadiazole). These polymers were studied when isolated at a low concentration in a polymer matrix (either polynorbornene or polystyrene). For the red-emitting polymer, we compare the relative emission intensity from the green-emitting benzothiadiazole groups with the red-emitting thiophene. We find that red emission from the thiophenes is significantly suppressed in the single molecule regime, suggesting that interchain energy transfer dominates intrachain processes in such polyfluorene copolymers. We then use fluorescence spectroscopy and polarization anisotropy measurements to show that the conformations of both polymers are dependent on their host matrix, adopting a more collapsed, globular conformation in polystyrene and a more extended chain conformation in polynorbornene.

Posterolateral rotatory instability of elbow: an uncommon entity.

Posterolateral rotatory instability of elbow is an exceedingly uncommon entity, which results from injury to the lateral ligamentous complex. Failure of adequate healing of lateral collateral ligaments may necessitate its surgical repair or reconstruction. We describe here a boy 12 years of age who was initially treated as soft tissue injury and later presented with instability of the same elbow. He later required repair of lateral ulnar collateral ligament.

[Solitary fibrous mediastinal tumor. A case report]. / Tumeur fibreuse solitaire du médiastin. A propos d'un cas.

Solitary fibrous tumor is a rare tumor, generally located in the pleura. Recently, new sites have been described in the literature, particularly involving the peritoneum and mediastinum, as wekk as te-the bronchopulmonary and orbital regions. The diagnosis is established at pathology, but in some cases may be difficult to differentiate from other tumors. We report the case of a 60-year-old women who had undergone surgery 25 years ago for right pulmonary hydatid cyst and who presented inspiratory dyspnea and dry cough for four months. Physical examination revealed a right cervical tumefaction in the supraclavian region. The AP chest x-ray disclosed an opacity in the right laterotracheal upper cervicomediastinal zone laminating the trachea which was displaced to the left. Thoracic computerized tomography showed a tissular process in the superior and middle mediastinum. Surgical tumor resection was performed and pathology confirmed the diagnosis of solitary fibrous tumor. The postoperative period was uneventful. Frequency of the mediastinal localisation is the same in men and women. The tumor generally develops between the 5th and 7th decades, and is most often asymptomatic. Fortuitous discovery is the rule. The clinical course is unforeseeable.

[Primary non-Hodgkin lymphoma of the mandible: apropos of three cases]. / Lymphome non hodgkinien mandibulaire primitif. A propos de trois observations.

BACKGROUND: Primary non-Hodgkin lymphoma is rarely located in bony tissue, observed in only 5% of primary bone tumors and 4-6% of extranodal non-Hodgkin lymphomas. The mandibular localization is exceptional (0.6%). Clinical and histological features may be misleading, raising the risk of late diagnosis. Chemotherapy and radiotherapy are required. CASE REPORTS: We report three cases of primary non-Hodgkin lymphoma of the mandible diagnosed between 1993 and 2000. All patients were males, aged 9, 37, and 45 years. Mean delay to diagnosis was 8 months. The inaugural complaint was a painful mass of the mandible in all patients. The histomorphology study and immunohistochemistry established the diagnosis. Two patients had diffuse large B cell non-Hodgkin lymphoma, the third anaplastic non-Hodgkin lymphoma. All patients were staged IE and given chemotherapy, associated with radiotherapy in one case. All patients achieved complete remission and continued to be in good health during follow-up lasting from 1 to 9 years.

Bilateral anterior and posterior traumatic hip dislocation.

SUMMARY: A case report of simultaneous traumatic bilateral anterior and posterior hip dislocations is presented, and the management of this injury is discussed.

Hepatitis B virus infection in pregnant women and its transmission to infants.

HBsAg was screened by Reverse Passive Haemagglutination Test (RPHA) and was confirmed by ELISA test in 157 pregnant females and their newborns. Anti-HBc and IgM anti-HBc was done in these cases by enzyme immuno-assay. The overall prevalence of HBsAg in mothers was 16 out of 157 (10 per cent) and in cord blood of newborns 5 per cent. The transplacental transmission was found in eight of 16 (50 per cent) HBsAg positive mothers. Anti-HBc was present in 12 out of 16 (75 per cent) HBsAg positive mothers and, of these, seven (58 per cent) neonates acquired HBsAg infection. IgM anti-HBc was present in seven out of eight (88 per cent) HBsAg positive neonates, suggesting active in utero infection. Fourteen out of 16 (88 per cent) neonates born to HBsAg positive mothers were alive and healthy, one was stillborn and one had a congenital anomaly.

[Adenocarcinoma of the third part of the duodenum]. / Adénocarcinome du troisème duodénum.

Adenocarcinoma of the third part of the duodenum is a rare tumour (34 cases reported in the literature). The clinical signs are polymorphic and non-specific and the stenotic form is the most frequent (57%). Complications are numerous and frequent. The difficult radiological diagnosis reveals either a short stenosis, a filling defect or, more rarely, and enlarged duodenal shadow or an ulcer. Duodenal fibroscopy allows the histological diagnosis and the differential diagnosis with other duodenal tumours. Adenocarcinoma of the third part of the duodenum requires cephalic duodenopancreatectomy (operative mortality of about 16%), which is the only treatment allowing a 3-year survival in 50% of cases and a 5-year survival in 30-40% of cases.