Phenol Oxidase

Phenol oxidase is an enzyme which is responsible for hydroxylation of phenols and dehydrogenation of O. diphenols into quinone. It is known to be distributed in the blood as well as in the cuticle of crustaceans (Summers, 1967). The enzyme can be assayed either spectrophotometrically, by measuring the dopa chrome formed (Preston & Taylor, 1970) or monometrically by measuring the oxygen. consumed during the oxidation of the substrates (Hackman & Goldberg, 1967). The spectrophotometry method of assaying the enzyme of blood from Scylla serrata is presented here

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Retrospective analytical five months study of aortic arch abnormalities

Background: Aortic arch abnormalities include congenital anomalies and acquired pathologies. Many of aortic arch congenital anomalies are asymptomatic lesions. But some of these anomalies are symptomatic and need to be treated. Radiological appearances should be familiar for these anomalies to the radiologist for correct interpretation. Aortic arch abnormalities reported in our institute are analysed in this article.Methods: This is a retrospective analytical study of five months from July 2015 to October 2015. The study was carried in the radiodiagnosis department of tirunelveli medical college hospital. In our institute, 494 cases of Computerised tomography (CT) Chest scans have been taken in above period for various conditions. In which Patients with vascular abnormalities of aortic arch in the scan were selected for the study i.e. sample selection. No of patients selected for analysis are 20. They have undergone CT scan, Magnetic resonance angiography (MRI) scan. Those findings were analysed and hereby are presented, in which age varied as low as 1 year and as high as 78 years.Results: Most of aortic arch abnormality cases belong to age group 60-80. About 75% of aortic abnormalities are acquired. The aortic arch abnormalities are commoner in males than females especially acquired diseases of aorta. Rare cases of Double aortic arch, aberrant right subclavian artery with dissection of aorta are diagnosed in these patients.Conclusions: It is noted that acquired conditions are the commonest abnormalities. CT scan and MRI complement each other. MR angiogram gives definitive diagnosis in aortic arch abnormalities. Double aortic arch is most common symptomatic vascular ring. MRI is the best single imaging study for the diagnosis and characterization of vascular rings. Aortic dissection needs urgent imaging. Multislice CT, MRI has replaced conventional angiogram.

Optimization of hydrothermal-assisted alkali process for enhanced xylan recovery from banana fiber biomass

Banana fiber is a rich lignocellulosic biomass source that has not been widely explored. The hemicellulose components (15 - 20 %) of banana fiber can be a feedstock for producing high-value commodity chemicals. Hemicellulose is extracted by physical, chemical, and biological methods, in which combining hydrothermal treatment with alkaline mode of extraction provides an enhanced recovery percentage. Thus, the present study aimed to optimize the hydrothermal-assisted alkaline method of xylan extraction from the banana fiber biomass. Initially, xylan was extracted with a conventional-based alkali method. A maximum of about 43 and 35 % was recovered from pretreated and raw banana fiber at 12% NaOH concentration when incubated at 55 °C for 24 h. To improve the xylan yield, the hydrothermal assisted alkali method experimented in which 67.1% and 58.3 % of xylan were recovered when treated at 121 °C for 1 h at 12% NaOH. To further enhance the xylan recovery, a two-step alkali process by combining conventional and hydrothermal-assisted alkali methods resulted in the highest xylan (81%) recovery from pretreated banana fiber when incubated with 12 % alkali for 8 h followed by steam treatment. On the other hand, a maximum of 73 % of xylan was recovered when steam treated after incubation for 24 h from raw banana fiber. Thus, the alkali incubation followed by steam treatment significantly showed the highest xylan recovery from the banana fiber biomass. The extracted xylan might be utilized as a source for various xylan-based products, including furfural, xylooligosaccharides, xylose, and xylitol, all of which have significant roles in the pharmaceutical and food industries

Radiological Evaluation of Primary Brain Tumours using Computed Tomography and Magnetic Resonance Imaging.

Brain tumours are among the common neoplasms of humans. Patients tend to concentrate in institutions where diagnostic and the Therapeutic services are available. The incidence of brain tumors is around 4 per 1,00,000 population. Supratentorial brain tumours constitute about 80% of brain tumours in adults and 40% of tumours in paediatric Population. Brain neoplasms are found in 2% of autopsy series and account For 1% of all the hospital admissions. Diagnosis of brain tumours may be delayed as the initial symptoms And signs are vague and nonspecific. The symptoms include headache, Focal seizures and focal neurological deficit, with clinical examination Revealing, raised intracranial tension or focal neurological deficit. Therefore the clinicians rely heavily on imaging for an early and Accurate diagnosis. Significant advance has been made during the last two Decades in radiological diagnosis and characterization of brain neoplasms. The goals of diagnostic imaging in the patient with suspected Intracranial tumor include detection of the presence of a neoplasm, Localization of the extent of the tumor (including definition of involvement Of key structures and assessment of the presence and severity of secondary Changes, e.g., edema, herniation, hemorrhage), and characterization of the Nature of the process.this has been made possible by modern imaging Modalities like ct and mri and refinements of previous technique such as Angiography. In addition stereotactic biopsy under imaging guidance Permits histological diagnosis of brain neoplasm. Both CT and MRI Provide Excellent Anatomic details and Information regarding the presence, location and extent of brain tumours. COMPUTED TOMOGRAPHY: Ct has the capacity to differentiate a wide range of tissue types Including air, fat, soft tissue and bone with superior spatial resolution. The Use of iodinated contrast agents allow better delineation of vascular Anatomy and pathological entities, and can differentiate enhancing lesion From surrounding reactive change. CT is highly sensitive to calcification and Blood within the brain parenchyma. CT is preferred for the uncooperative And unstable patients, because each axial image is obtained separately. Thus, motion artifact is minimized, particularly in later generation scanners Which can perform individual scans in less than 2 seconds. CT characterization provides a better insight to the nature of lesion And its effect on the adjacent structures. It also provides a road map for the Neurosurgeon regarding the approach, likely duration of surgery, Requirements for anaesthesia etc. Upgradation in recent ct technologies like helical mode helps in 3 Dimensional visualization of the neoplasm. Wider experience in ct and familiarity of the lesions in ct favor ct As an important and appropriate investigation tool. Magnetic Resonance Imaging : MRI has rapidly earned recognition as the optimal screening Technique for the detection of most intracranial neoplasms. Compared with CT, MRI using spin echo, gradient echo, and combination spin and gradient Echo pulsing sequences before and after intravenous (iv) administration of Paramagnetic contrast agents provides inherently greater contrast resolution Between structural abnormalities and adjacent brain parenchyma and has Proved to be even more sensitive in the detection of focal lesions of the Brain. Early experience suggested that upto 30% more focal intracranial Lesions could be identified on MRI than on CT

Platinum substituted Cobalt(II, III) Oxide: Interplay of tetrahedral Co(II) sites towards electrochemical oxygen evolution activity

Substitution of ionic platinum is carried out in Co3O4 host synthesized by solution combustion strategy. These Pt substituted Co3O4 spinels characterized by XRD show pure crystalline phase of Co3O4 without any separated peaks related to Pt/PtOx. Electrochemical OER activities of these spinels are investigated by cyclic voltammetry, linear sweep voltammetry and chronoamperometry in neutral, alkaline and neutral buffer electrolytes. LSV studies on 1% Pt substituted Co3O4 exhibit a low overpotential (¿) of 455 mV at 20 mA cm-2 in KOH, as compared to PBS medium. Tafel slope value of 117 mV dec-1 in KOH represents one electron EC mechanism. The detailed XPS studies indicate that Pt doping increases the tetrahedral Co2+ sites of Co3O4. XPS studies before and after OER also infers that the mixed valence of Co in the host (Co3O4) undergoes redox (Co2+/Co3+) changes with simultaneous reduction in Pt dopant from Pt4+ to Pt2+ influencing the OER activity

High-Entropy Alloys as Catalysts for the CO2 and CO Reduction Reactions: Experimental Realization

Conversion of carbon dioxide into selective hydrocarbon using a stable catalyst remains a holy grail in the catalysis community. The high overpotential, stability, and selectivity in the use of a single-metal-based catalyst still remain a challenge. In current work, instead of using pure noble metals (Ag, Au, and Pt) as the catalyst, a nanocrystalline high-entropy alloy (HEA: AuAgPtPdCu) has been used for the conversion of CO2 into gaseous hydrocarbons. Utilizing an approach of multimetallic HEA, a faradic efficiency of about 100% toward gaseous products is obtained at a low applied potential (−0.3 V vs reversible hydrogen electrode). The reason behind the catalytic activity and selectivity of the high-entropy alloy (HEA) toward CO2 electroreduction was established through first-principles-based density functional theory (DFT) by comparing it with the pristine Cu(111) surface. This is attributed to the reversal in adsorption trends for two out of the total eight intermediates—*OCH3 and *O on Cu(111) and HEA surfaces

Hemocyanin conformational changes associated with SDS-induced phenol oxidase activation

The enzymatic activity of phenoloxidase is assayed routinely in the presence of SDS. Similar assay conditions elicit phenoloxidase activity in another type 3 copper protein, namely hemocyanin, which normally functions as an oxygen carrier. The nature of the conformational changes induced in type 3 copper proteins by the denaturant SDS is unknown. This comparative study demonstrates that arthropod hemocyanins can be converted from being an oxygen carrier to a form which exhibits phenoloxidase activity by incubation with SDS, with accompanying changes in secondary and tertiary structure. Structural characterisation, using various biophysical methods, suggests that the micellar form of SDS is required to induce optimal conformational transitions in the protein which may result in opening a channel to the di-copper centre allowing bulky phenolic substrates access to the catalytic site

Not Available

Not AvailablePhenol oxidase is an enzyme which is responsible for hydroxylation of phenols and dehydrogenation of O. diphenols into quinone. It is known to be distributed in the blood as well as in the cuticle of crustaceans (Summers, 1967). The enzyme can be assayed either spectrophotometrically, by measuring the dopa chrome formed (Preston & Taylor, 1970) or monometrically by measuring the oxygen. consumed during the oxidation of the substrates (Hackman & Goldberg, 1967). The spectrophotometry method of assaying the enzyme of blood from Scylla serrata is presented here.Not Availabl