Ratiometric temperature measurement using negative thermal quenching of intrinsic BiFeO3 semiconductor nanoparticles.

A strategy for optical nanothermometry using the negative thermal quenching behavior of intrinsic BiFeO3 semiconductor nanoparticles has been reported here. X-ray diffraction measurement shows polycrystalline BiFeO3 nanoparticles with a rhombohedral distorted perovskite structure. Transmission electron microscopy shows agglomerated crystalline nanoparticles around 20 nm in size. Photoluminescence measurements show that intensity of the defect level emission increases significantly with temperature, while the intensity of near band emission and other defect levels emissions show an opposite trend. The most important figures of merit for luminescence nanothermometry: the absolute (S a) and the relative sensor sensitivity (S r) and the temperature resolution (ΔT m) were effectively resolved and calculated. The relative sensitivity and temperature resolution values are found to be 2.5% K-1 and 0.2 K, respectively which are among the highest reported values observed so far for semiconductors.

Structural, optical and vibrational properties of self-assembled Pbn+1(Ti1-x Fex)nO(3n+1)-δ Ruddlesden-Popper superstructures.

Bulk crystals and thin films of PbTi(1-x)FexO3(-δ) (PTFO) are multiferroic, exhibiting ferroelectricity and ferromagnetism at room temperature. Here we report that the Ruddlesden-Popper phase Pbn+1(Ti(1-x)Fex)nO3(n+1)-δ forms spontaneously during pulsed laser deposition of PTFO on LaAlO3 substrates. High-resolution transmission electron microscopy, x-ray diffraction and x-ray photoemission spectroscopy were utilised to perform a structural and compositional analysis, demonstrating that n ≃ 8 and x ≃ 0.5. The complex dielectric function of the films was determined from far-infrared to ultraviolet energies using a combination of terahertz time-domain spectroscopy, Fourier transform spectroscopy, and spectroscopic ellipsometry. The simultaneous Raman and infrared activity of phonon modes and the observation of second harmonic generation establishes a non-centrosymmetric point group for Pbn+1(Ti0.5Fe0.5)nO3(n+1)-δ, a prerequisite for (but not proof of) ferroelectricity. No evidence of macroscopic ferromagnetism was found in SQUID magnetometry. The ultrafast optical response exhibited coherent magnon oscillations compatible with local magnetic order, and additionally was used to study photocarrier cooling on picosecond timescales. An optical gap smaller than that of BiFeO3 and long photocarrier lifetimes may make this system interesting as a ferroelectric photovoltaic.

Cystic meningiomas, a diagnostic and pathogenic challenge.

A 55-year-old woman presented with focal seizures, then rapidly evolving hemiplegia. Brain CT and MRI showed a large cystic lesion of the right frontal lobe with a small enhancing nodule adjacent to the dura. The nodule corresponded to a meningioma on pathological examination, and the operative findings suggested that the cyst was due to local entrapment of CSF by the tumor and its arachnoid adhesions. The rapid clinical deterioration was probably due to the rapid expansion of the cyst volume. Pathogenesis and unusual radiological appearances of cystic meningiomas are discussed.

Brain magnetic resonance imaging in non-alcoholic cirrhosis.

Twenty-six patients with stable non-alcoholic cirrhosis and normal neurological examination were investigated by brain MRI (inversion recovery sequences) and compared with 16 controls. Brain MRI findings were correlated with the clinical and metabolic status of the patients and analysis of variance and, when necessary, co-variance was performed. Five of the patients (19%) and all 16 controls showed no MRI changes. Twelve patients (46%) showed moderately high signal in the globus pallidus (score 1), and nine (35%) very high signal (score 2). Analysis of variance showed that age was the only significant variable (P = 0.038). Analysis of co-variance after adjustment for age showed that high pallidal signal was correlated only to ammonia level (P = 0.02) but not to any other clinical or biological parameter. We conclude that T1 high intensity pallidal signal is common in non-alcoholic cirrhosis even when neurological examination is normal, but its significance remains unclear.

Gastric carcinoids--a clinicopathologic study.

AIM: Our objective was to document the clinical and pathological findings in eight patients with gastric carcinoids seen in our institution over a 16-year period (1980-96). METHODS: All cases reported during this period as microcarcinoids, atypical carcinoids and mixed carcinoid-carcinoma of the stomach were retrieved from pathology records. Eight cases with typical histologic features of carcinoid were studied. RESULTS: Seven cases were men (median age 53 years, range 35-55). Four patients presented with upper abdominal pain. Serum gastrin level was elevated in two cases. The endoscopic appearances and the endoscopic biopsy histology were not diagnostic. Surgical treatment ranged from simple nodule excision to partial, subtotal or extended gastrectomy and Whipple's pancreatico-duodenectomy. Lymph node and liver metastasis were seen in four patients each. The median duration of follow-up was one year. CONCLUSION: Gastric carcinoids have varied etiopathogenesis. These may arise in a background of hypergastrinemic conditions or may be sporadic. Most appear to be slow growing but aggressive neoplasms are capable of distant metastasis.

Adenocarcinoma arising in "J" pouch after total proctocolectomy for familial polyposis coli.

A patient of familial adenomatous polyposis (FAP) without extra intestinal lesions is presented. The patient underwent a proctocolectomy with J pouch ileal reservoir with an ileoanal anastomosis. The clinical course was further complicated by an adenocarcinoma developing in the J pouch. This was excised totally and a terminal illeostomy was constructed. The aim of doing a prophylactic proctocolectomy in familial polyposis coli is to prevent a malignancy developing and to restore function with an illeoanal pouch. However polyps can occur in the gastric, duodenal and intestinal mucosa, which can lead to malignancy. Greater awareness and close follow up is needed even after prophylactic proctocolectomy.

Urinary retention revealing a tuberculoma of the conus medullaris in a patient with intracranial tuberculosis: case report.

Central nervous system involvement in tuberculosis is still common in developing countries and can present in a variety of clinical pictures. We report a patient with tuberculous meningitis combined with intra-cerebral tuberculomas, where the presence of unexplained urinary retention led to the discovery of an additional tuberculoma of the conus medullaris. The patient responded well to conservative treatment.

Patent omphalomesenteric duct of the vermiform appendix in a neonate: congenital appendicoumbilical fistula.

Umbilical anomalies arise from fetal structures such as the omphalomesenteric duct (OMD) or urachus or from failure of closure of the umbilical fascial ring. Persistence of the OMD may lead to several anomalies including umbilical sinus, umbilical cyst, Meckel's diverticulum, or patent OMD (POMD). A POMD is usually associated with the ileum, but rarely may be with the caecum or appendix. We describe a POMD of the vermiform appendix and discuss the possible pathogenesis and management.

Studies on ayurvedic tablets - part I disintegration time as a preliminary tool for standardisation.

The ayurvedic pharmacy needs to be established on the basis of modern quality standards. A study on ayurvedic Guti-Vati (tablets) was undertaken with this view, revealed that most of the tablets conform to the I P standards for hardness and DT. A few of the tablets showed curious responses similar to that of enteric coated and slow release tablets commonly used in modern medicine.A systematic supporting study is essential so as to establish relationship of such responses to the nature of ingredients and their relevance with the indications and therapeutic utility described in Ayurvedic texts.

Hemiconvulsion-hemiplegia-epilepsy syndrome. A clinical, electroencephalographic and neuroradiological study.

Six patients (4 boys and 2 girls) with hemiconvulsion-hemiplegia-epilepsy (HHE) syndrome are described. They had prolonged seizures, lasting from 30 min to 12 h, at ages 1-4 years. These took the form of hemiconvulsion in three of the children and generalized tonic-clonic seizures in the others, being preceded by hemifacial twitching or head and eye deviation in two. They were followed by hemiplegia, which cleared with time in five patients, apart from subtle pyramidal tract signs. One child had spastic quadriparesis, choreiform movements, contracture deformities and severe mental retardation following repeated status epilepticus. Subsequent epilepsy developed in five patients and was satisfactorily controlled with carbamazepine and/or phenobarbitone. Cerebral hemiatrophy was documented in all patients by cranial computed tomography and/or magnetic resonance imaging. Single photon emission computed tomography (done in 4 patients) showed ipsilateral hypoperfusion (of the damaged hemisphere). Electroencephalography showed ipsilateral slowing and low voltage of background activity. Epileptiform discharges were found on the ipsilateral side in two cases and the contralateral side (the undamaged hemisphere) in one.