654 research outputs found
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Chemometric assisted RP-HPLC for fingerprinting of Indian orthodox black tea
No full textIn view of the large variation in tea quality, this study aims to fingerprint the best quality of Indian orthodox black tea depending upon the production region, variation of seasons, mechanical grading and processing with different fermentation times. A HPLC method reported by us earlier has been adapted to separate biochemical constituents in various tea samples, in which Thermo Hypersil ODS column has been found to be more efficient in terms of resolution and retention time. Even black tea processed from the same region but processed in different seasons or mechanically graded resulted in significant compositional changes. The average data from HPLC was subjected to chemometric analysis i.e. principal component analysis (PCA). Different clusters were obtained for each type of tea which can act as a fingerprint for further analysis and interpretation of tea quality for its ranking. Thus, HPLC integrated with chemometrics can be explored as a routine diagnostic tool for online monitoring of black tea quality
Characterization of solid state forms of glipizide
No full textIn the present study various crystalline forms of glipizide were prepared in order to enhance dissolution rate of glipizide and to evaluate the stability of developed forms. Four different strategies have been followed to prepare crystalline forms of glipizide – a. crystallization from the methanolic solution of the drug under pH control b. crystallization by vapor diffusion c. crystallization by antisolvent precipitation technique and, d. quench cooling. It could be deciphered from the study of DSC, SEM, PXRD and Raman spectroscopic analysis that six different crystal forms of glipizide (form I, form II, form III, form IV, form V and form VI) were prepared. Among all crystalline forms, the fastest T50% drug release was observed with form III and form V (i.e. within 10 min). However, T50% drug release was not observed in case of pure glipizide even till 90 min Among all the crystal forms prepared, it was concluded that form V (JMD-7) prepared by diffusing vapors of chloroform in the saturated solution of glipizide in methanol could be considered the best due to its rapid dissolution rate (T50% is 10 min), considerably higher extent of dissolution (Q90 is 87.22%) and better stability (F2 value 65.39 between dissolution profiles of fresh and aged form V). Further, the dissolution profile (F2 = 75), PXRD pattern and DSC thermograms of form V of glipizide converted in capsule dosage form were found similar as that of glipizide powder (form V). This justifies that the manufacturing process will not change the dissolution rate or chemical properties of the difference forms of API
Experimental Investigation on Uncontrollable Parameters for Surface Finish during Diamond Turning
No full textSingle point diamond turning is one of the ultraprecision methods to generate high quality surfaces with highest possible profile accuracies. However, diamond turning process also introduces some unique errors which affect the surface finish. Some of these errors are controllable, while some are noncontrollable. Controllable parameters need proper selection, whereas uncontrollable parameters require adequate understanding of the process behavior. In this study only the effect of uncontrollable parameters on surface finish is explored. Tool overhang results tool–workpiece vibration whereas dynamic unbalance of vacuum responsible for workpiece wobble and both affect the surface finish considerably. Chipping of tool edge, improper extraction of chips, and slipping of workpiece on vacuum chuck are the main reasons of random scratch marks on surface and are contributing factors for degradation of surface finish
Multispectral Image Fusion for Enhancing Situation Awareness: A Review
No full textThe human inability to see clearly in dark/night times has been a research challenge for many decades. Night vision equipment have been extensively used in the defence sector for carrying out hassle-free operation in low visibility or dark operating conditions, but with a limitation that they are essentially monochrome (green/grey) in colour. The comprehension ability using such images is reduced and results in poor situation awareness (SA). Fusion of multispectral images has therefore been seen as a solution to the problem. Various researchers have come up with different ideologies/algorithms over the time. In this paper, the focus is to discuss about techniques developed in recent past with a vision to explore best upcoming multispectral image fusion solutions for combining visible and infrared images, which could lead to a better target detection/recognition and SA
Role of photoadduct of K4 Fe(CN)6 and C3 H4 N2 in improving thermal stability of polyaniline composite
No full textThis paper involves the synthesis of polyaniline composite with photoadduct of potassium hexacyanoferrate and imidazole via photochemical route by oxidative polymerization technique by ammonium persulphate. The photoadduct has been synthesized by photoirradiation followed by substitution with imidazole ligand. The photoaquation, substitution and successful synthesis has been proved by recording pH, UV visible spectra before and after irradiation and XRD of photoadduct. The as synthesized composite has been subjected to various characterizations like elemental analysis, UV–Visible spectra, FTIR, XRD, SEM, and TG/DTG. XRD of photoadduct shows crystalline structure which has been retained in the composite, changing the amorphous structure of polyaniline into the crystalline one, hence proving the insertion of photoadduct in the polymer chain. Various parameters like crystallite size (L), interplanar distance (d), micro strain (ε), dislocation density (δ) and distortion parameters (g) were calculated from XRD data. Thermal analysis shows the high thermal stability of composite which can be due to strong interaction between polymer chain and the photoadduct which restricts the thermal motion of polyaniline and thus enhances the thermal stability of composite
A Beta Regression Model for Himalayan Medicinal Plant Disease Prediction
No full textPicrorhiza kurrooa plants were grown in greenhouse and was tested for powdery mildew disease. The result of temperature and wetness duration on P.kurrooa was studied under controlled-environment to develop a disease prediction model for controlling infection.Plants were kept at a temperature ranging from 31°C to 37°C with Relative Humidity (RH) more than 90% was maintained in greenhouse and it is measured in the terms of wetness duration (in hours) from 5 to 40hr.To determine the relationship between infection index, temperature and wetness duration data for P. kurrooa were analyzed
by nonlinear regression model. Beta model was used to provide the best fit to the data for modeling. Infection index on plant increased with increasing wetness duration at optimum temperature. Minimum and maximum temperatures for infection were around 31 and 37°C, respectively. At 35.5°C maximum infection was recorded, and a minimum duration of wetness that is required for germination of the fungus was 5hr. Highest infection index 0.95 was noticed at 35.5°C. Temperature and duration of wetness were recorded for each event and used in the model equation to calculate disease infection index. Regression coefficient (R2) between observed infection index and predicted infection index was 0.8103 and coefficient of determination (R) was 0.9. It indicates that the model could reliably predict the disease infection index over
a wide range of temperatures and wetness durations
Rapid HPLC method development for determination of vitamin C, phenolic acids, hydroxycinnamic acids, and flavonoids in Emblica officinalis juice
No full textThe work proposes a simple method for simultaneous detection and quantification of vitamin C (ascorbic acid), phenolic acids (gallic acid and ellagic acid), hydroxycinnamic acid (chlorogenic acid), and flavonoids (myricetin, quercetin, and kaempferol) in seasonal samples of emblica juice. The compounds were separated by an intangible curved gradient of 0.1% orthophosphoric acid in water (v/v) and acetonitrile as mobile phase A and B using Zorbax SB RP C-18 column at a wavelength of 254 nm in 18 min. The assay was optimized by varying the mobile phase, gradient type, and detection wavelength. The method was validated in terms of linearity, precision, detection limits, and quantification limits. Good linear response was observed over the range specified for all the analytes, as confirmed by the correlation coefficient which ranged from 0.991 and 0.995. The limit of detection and limit of quantification were found to be in the range of 0.129–0.685 µg mL−1 and 0.43–2.883 µg mL−1, respectively. Complete resolution of the phenolic compounds was achieved without the need of pre-analysis processes. The overall precision values obtained for standards and samples were within the range of 0.01–0.2 and 0.15–0.23, respectively
Effects of tool overhang on selection of machining parameters and surface finish during diamond turning
No full textIn precision machining leading to nano-metric surface finish, selection of the suitable machining parameters is a critical task. To ensure the desired surface quality, one needs to optimally select the machining parametric matrix. Towards this effort, this paper adds another critical parameter in terms of tool overhang. A well-defined set of machining exercises is carried out with different tool overhangs and machining parameters. In this investigation, an attempt has been made to locate the optimum range of tool overhang with minimum tool vibrations. The interaction between tool overhang with other parameters is also thoroughly investigated. Another important focus of this study is to find out the optimum machining parameters for the situations where it is not possible to select an optimum tool overhang. One such situation occurs when a steep concave parabolic surface needs to be fabricated. In this case a large tool overhang has to be selected. Power spectral density distribution analysis of surface roughness for different tool overhangs is performed to find out significant parameters and their degree of contribution to surface roughness. Analysis of variance is also applied to ascertain statistically significant factors contributing to surface roughness. To model the surface roughness, response surface methodology is being used. The model has been verified by conducting a series of experiments and a steep concave parabolic surface is developed by following the predictions of the developed model
Implementation of motion transfer in robotic surgery
No full textMinimally invasive surgery is a modern surgical technique in which the operating tools are inserted into the patient through small incisions. Robotic applications in general surgery have evolved from simple surgical assist devices, to more sophisticated systems capable of enhancing surgical performance. The primary class of robots used in general surgery today, are 'master-slave' machines, where the robot mimics the movement of the surgeon. A major drawback with the master-slave robotic systems is the motion coordination between the two. The paper discusses the techniques of motion transfer from master to slave and to implement force feedback from slave to master. Motion is transferred from master surgeon handle to the robotic arm depending on the encoder pulses from master configuration. The pulses from the encoder are processed and fed to the slave, which mimics the hand motion of master configuration. A two channel encoder with DC motor is used in master-slave configuration. The proposed configuration with force feedback capability enables the exact motion coordination between surgeon and robotic surgical system. This technique has a wide application, with accuracy, efficiency, safety and overall user experience that provide superior performance and reliability in master-slave robot-assisted interventions
Estimation and correction of geometric distortion of stroke-based symbology for avionics display system using curve fitting
No full textHigh-precision avionics display system like head-up display (HUD) are used to display the flight information of several selectable modes in the collimated form so that the pilot can view this information superimposed on his view of the outside world without changing his line of sight or visual accommodation. The information display symbology formed on the HUD is governed by the horizontal and vertical deflection signals as per the X- and Y-coordinates of the reticles which are synchronised with the blanking signal. Being an electro-opto-mechanical display, these displays are prone to the geometric distortions. This research work aims at establishing high positional accuracy of the display symbology by using a geometric distortion correction system (DCS) for stroke-based avionics display system based on curve fitting. The rectification is applied to images of three different HUDs, with respect to their placement of reticles, aiming to test residuals in X- and Y-axes. The developed system features simple approach, cheap expenses, high accuracy and its capability to provide real-time and accurate coordinates of the image displayed on the HUD