Single In x Ga1-x As nanowire/p-Si heterojunction based nano-rectifier diode.

Nanoscale power supply units will be indispensable for fabricating next generation smart nanoelectronic integrated circuits. Fabrication of nanoscale rectifier circuits on a Si platform is required for integrating nanoelectronic devices with on-chip power supply units. In the present study, a nanorectifier diode based on a single standalone In x Ga1-x As nanowire/p-Si (111) heterojunction fabricated by metal organic chemical vapor deposition technique has been studied. The nanoheterojunction diodes have shown good rectification and fast switching characteristics. The rectification characteristics of the nanoheterojunction have been demonstrated by different standard waveforms of sinusoidal, square, sawtooth and triangular for two different frequencies of 1 and 0.1 Hz. Reverse recovery time of around 150 ms has been observed in all wave response. A half wave rectifier circuit with a simple capacitor filter has been assembled with this nanoheterojunction diode which provides 12% output efficiency. The transport of carriers through the heterojunction is investigated. The interface states density of the nanoheterojunction has also been determined. Occurrence of output waveforms incommensurate with the input is attributed to higher series resistance of the diode which is further explained considering the dimension of p-side and n-side of the junction. The sudden change of ideality factor after 1.7 V bias is attributed to recombination through interface states in space charge region. Low interface states density as well as high rectification ratio makes this heterojunction diode a promising candidate for future nanoscale electronics.

Determination of pentafluorobenzyl derivatives of phosphonic and phosphonothioic acids by gas chromatography-mass spectrometry.

A method based on gas chromatography-mass spectrometry (GC/MS) has been evaluated and standardized for the analysis of pentafluorobenzyl (PFB) derivatives of alkylphosphonic, O-alkyl alkylphosphonic and phosphonothioic acids. The pentafluorobenzyl (PFB) derivatives are much more stable as compared to the conventionally used trimethylsilyl derivatives. The conditions for the derivatization and analysis have been optimized to achieve the best detection limits in negative chemical ionization (NCI) mode.

Anterior discectomy and fusion for the management of neck pain.

STUDY DESIGN: Data were collected prospectively on 38 patients who underwent anterior cervical discectomy and fusion for neck pain with no symptoms or signs of radiculopathy or myelopathy. OBJECTIVES: To determine the changes in pain and function after anterior cervical discectomy and fusion for nonradicular neck pain. SUMMARY OF BACKGROUND DATA: There is considerable controversy regarding the role of anterior cervical discectomy and fusion for neck pain in the absence of radiculopathy or myelopathy. Although no studies have addressed this specific and common problem, it is known that anterior cervical discectomy and fusion for radiculopathy or myelopathy may also provide relief of neck pain for many patients. METHODS: Thirty-eight patients who underwent anterior cervical discectomy and fusion for neck pain were evaluated. Before and after surgery, the authors measured pain with a numerical rating scale, function with the Oswestry Disability Questionnaire, and final patient satisfaction. Final evaluation was done by a disinterested third party. RESULTS: All 38 patients were available for follow-up study. Mean age was 42.4 years, and mean duration of follow-up study was 53 months. All patients had painful disc(s) proven by discography. No patients had nerve root compression. Anterior cervical discectomy and fusion was performed at one level in 21 patients, two levels in 16 patients, and three levels in one patient. The mean score on the numerical rating scale for neck pain before surgery was 8.3 (range, 3-10) versus 4.1 (range, 0-10) after surgery. This difference is significant (P < 0.001). The mean score on the Oswestry Disability Questionnaire was 57.5 (range, 0-89) before surgery versus 38.9 (range, 0-80) after surgery. This difference is significant (P < 0.001). There were 30 (79%) patients who were satisfied with their outcome, and 8 (21%) who were not satisfied. There was no statistical difference in change of pain or function between patients with worker's compensation and those with other insurance or between men and women. Twenty patients were not working because of neck pain before surgery, and 15 were not working at the time of follow-up examination. CONCLUSION: A significant decrease in pain, a significant increase in function, and a high degree of patient satisfaction were found with anterior cervical discectomy and fusion for neck pain. Improvements were not affected by worker's compensation status or gender.

Bilateral simultaneous retinal vein occlusion.

Central retinal vein occlusion (CVO) is a common retinal vascular disorder with potentially blinding complications. However, a simultaneous bilateral affection is not a common entity. One such patient is described here.

EVALUATION OF OCULAR DEVIATIONS AND PTOSIS AFTER CATARACT SURGERY.

There is a paucity in world literature of a prospective study on post cataract strabismus and in Indian literature on post cataract ptosis. 150 cataract patients without pre-existing strabismus or ptosis were subjected to standard extracapsular cataract extraction with posterior chamber intraocular lens implantation under 2 point peribulbar anaesthesia and were post-operatively evaluated for strabismus and ptosis. At the end of first week, there were 10/150 (6.67%) cases of strabismus, 13/150 (8.67%) cases of ptosis and 5/150 (3.33%) of both combined, which reduced to 2% each (3/150) at the twelfth week. The probable factors for causation and recovery are being discussed.

OCULAR DISABILITIES IN CANDIDATES FOR RECRUITMENT: AN ANALYSIS.

Analysis of recruit examination records of three years of the department of Ophthalmology of Command Hospital (SC) showed that of the 1579 candidates appearing for review, 558 (35.3S%) were for defective colour perception, 366 (23.18%) were for squint assessment and 330(20.9%) were for substandard vision. The initial examination of these candidates was done by a general duty medical officer whereas the review was done by an ophthalmologist Almost two-thirds of these candidates appearing for review were found fit {985/1579(68.39%)}. Squint was the leading disability for which these candidates were found fit {315/985 (31.99%)} while defective colour perception with 274/594 (46.12%) headed the list of candidates found unfit.

Small intestinal and hepatic amylase activity of different vertebrates and invertebrates.

Studies have been done on amylase activity of the small intestine and liver of toad, calotes, pigeon rat, guinea pig and pilaglobosa. It has been found that amylase activity was maximum in pigeon, rat, guinea pig and then in calotes and pilaglobosa and least activity was found in toad, and seem to be related to the phylogeny and the dietary habbit.

Comparative studies on different small intestinal oligosaccharidase activities in some vertebrates and invertebrates like molluscs.

Oligosaccharidase activities of the small intestinal mucosal homogenates were measured in vertebrates viz fish, toad, garden-lizard (calotes), pigeon, rat and some invertebrates viz, molluscsa. Maximum activities of the enzymes Lactase, Sucrase and Maltase were found in the mammalian species rat, whereas much less activities were found in the non-mammalian vertebrates among which toad shows the highest values and garden lizard the lowest. Among the invertebrates Pila globosa shows higher values of all the enzymes than Achatina fulica. The results obtained have been discussed in the lights of phylogeny and diet habits.