Specific Refractive Index Research Articles

RENDEMEN DAN KARAKTERISTIK MINYAK KAYU PUTIH PADA UKURAN DAUN YANG BERBEDA

This research was conducted in the presumptuous university forest faculty laboratory yellow Pekanbaru. This research was conducted for 6 months, namely from July -December 2018. This study aims to measure the yield and characteristics eucalyptus oil at various leaf sizes consisting of specific gravity, refractive index, solubility in 70% alcohol, and cineol content. Analyze effect size eucalyptus leaves to the characteristics of eucalyptus oil. This research is
 using a completely randomized design (CRD). This research is used to obtain provide information and input regarding the characteristics of eucalyptus oil and yield at different leaf sizes. Results from research on oil characteristics Eucalyptus at various leaf sizes consists of, whole eucalyptus leaves obtained yield 0.59%, moisture content 1.074%, specific gravity 0.953, refractive index 1.467, solubility in 70% 1: 2 alcohol, the cineol content is 71.67%. Two cut leaves are obtained yield 0.49%, moisture content 0.842%, specific gravity 0.921, refractive index 1.465, solubility in 70% alcohol 1: 3, cineol content 63.33. Cut eucalyptus oil leaves three obtained yield 0.39, water content 0.908, specific gravity 0.924, inex bias 1.465, solubility in 70% alcohol 1: 4, cineol content 68.33%. Treatment of leaf size significant effect on yield, solubility in 70% alcohol and not significant effect on specific gravity, refractive index, and cineol content.
 
 
 

ANALISIS SENYAWA BERBAHAYA PARFUM ISI ULANG YANG DIJUAL DI KOTA PADANG MENGGUNAKAN METODE KROMATROGRAFI GAS-SPEKTROMETRI MASSA

Perfume is widely used by most of people in this world. The increasing demand of perfume has caused many producers cheating by adding dangerous compounds and also unregistered by the National Agency of Drug and Food Control Indonesia. The aim of this study is to analyze the dangerous compounds in unregistered perfumes sold in Pasar Raya Padang City by using gas chromatography-mass spectrometry (GC-MS) method. In this Study, samples (A, B, C, D and E) were collected and the value of specific weight and refractive index of the samples were analyzed. The results showed that five samples contained relatively similar chemical compounds. Twelve compounds were detected and seven of them were harmful to health in refill perfumes which were dipropylene glycol, linalool, lily aldehyde, benzenepentanol, dimethylbenzyl carbinyl acetate, dihydro methyl jasmonate, alpha hexyl cinnamic aldehyde, based on Material Safety Data Sheet (MSDS). Regular monitoring of chemicals used in the manufacture of perfumes which may cause health risks to users should be controlled by National Agency of Drug and Food Control Indonesia.

Real-Time Interferometric Refractive Index Change Measurement for the Direct Detection of Enzymatic Reactions and the Determination of Enzyme Kinetics.

Back scatter interferometry (BSI) is a sensitive method for detecting changes in the bulk refractive index of a solution in a microfluidic system. Here we demonstrate that BSI can be used to directly detect enzymatic reactions and, for the first time, derive kinetic parameters. While many methods in biomedical assays rely on detectable biproducts to produce a signal, direct detection is possible if the substrate or the product exert distinct differences in their specific refractive index so that the total refractive index changes during the enzymatic reaction. In this study, both the conversion of glucose to glucose-6-phosphate, catalyzed by hexokinase, and the conversion of adenosine-triphosphate to adenosine di-phosphate and mono-phosphate, catalyzed by apyrase, were monitored by BSI. When adding hexokinase to glucose solutions containing adenosine-triphosphate, the conversion can be directly followed by BSI, which shows the increasing refractive index and a final plateau corresponding to the particular concentration. From the initial reaction velocities, KM was found to be 0.33 mM using Michaelis–Menten kinetics. The experiments with apyrase indicate that the refractive index also depends on the presence of various ions that must be taken into account when using this technique. This study clearly demonstrates that measuring changes in the refractive index can be used for the direct determination of substrate concentrations and enzyme kinetics.

Yield, Quality and Composition of Cumin Essential Oil as Affected by Storage Period

Essential oils from newly produced (2017) and previous season crop (2016) of cumin (Cuminum cyminum L.) seeds collected from local farmers in Dongla area, north Sudan were extracted and analyzed to determine the effect of storage period on volatile oil yield and quality. The essential oil was extracted using hydro distillation method. Identification of the volatile compounds was performed using gas chromatography-mass spectrometry (GC/MS). Results revealed that oil obtained from cumin (Cuminum cyminum L.) was pale yellow. With respect to oil characteristics, the specific gravity, refractive index, acid value, ester value and other quality characters were not significantly different between the stored and newly harvested seeds. Thirty-eight compounds were separated and identified in cumin seeds essential oil in both seasons with some minor differences in some components between 2016 and 2017 samples. Major effective components of cumin seeds volatile oil were cumin alcohol (4-isopropylbenzyl alcohol), cumin aldehydes as 4-Isopropylbenzaldehyd and 7,7-dimethylbicyclo (4.1.0) hept-3-ene-4-carbaldehyde known as carenal, terpinenes as γ-terpinene and α-terpinene (1,4-Cyclohexadiene, 1-methyl-4-(1-methylethyl) and 1,3-cyclohexadine-1-methanol, 4(1-methethyle)-), β-pinene, o-cymene and p-menthadienol in both stored and newly harvested samples. Differences between the samples season wise were very minor with respect to type of volatile components but percentage oil yield was largely decreased by storage period.

Improving silver mirrors with aluminum oxynitride protection layers: variation in refractive index with controlled oxygen content by radiofrequency magnetron sputtering

According to the demand for high-performance silver-based telescope mirrors, attempts are being made to develop surface coatings that protect the mirrors from corrosion. Aluminum nitride (AlN) is utilized for various optical coatings, and its high optical transparency and mechanical robustness make it potentially well suited as a protective coating of silver-based mirrors. However, according to our best knowledge, AlN with controlled oxygen content has never been used to protect silver mirrors. Various protective coatings based on AlN are prepared by RF magnetron sputtering. Specific amounts of oxygen are deliberately introduced to obtain aluminum oxynitride (AlON) protective layers with refractive indices within a certain range (i.e., high ∼2.1, medium ∼1.8, and low ∼1.6 at 400 nm). The designed protective layers are applied to two types of silver-based mirror test structures, and their performance was assessed in terms of optical reflectivity and structural integrity of the test structures that underwent environmental testing in a controlled atmosphere at 80°C with ∼80 % relative humidity. Comprehensive analysis on the samples before and after the environmental testing indicates that AlON-based 41- and 56-nm protective layers with medium refractive index outperform similar samples using AlON with higher or lower refractive index. We suggest that the benefits of the best AlON barrier with specific refractive index are likely associated with the optical, chemical, and structural characteristics produced with sputtering conditions that yield a nitrogen/oxygen ratio of approximately one.

Antireflective mesoporous silica coatings by optimization of water content in acid-catalyzed sol-gel method for application in glass covers of concentrated photovoltaic modules

Porous silica layers with outstanding antireflective properties have been prepared by acid-catalyzed sol-gel process in presence of organic phases as structure directing agents (SDA) and excess water, with the aim of offering a cost-competitive, easy up-scaling and high efficiency process that contributes to reduce current levelized cost of energy (LCOE) of concentrating photovoltaics (CPV). The process has been optimized by controlling the water/alkoxide ratio, which is an important structure-regulating tool, having a strong influence in the structural properties of sol-gel synthesized materials. Hydrolysis of the inorganic precursor has been accomplished in high water/alkoxide conditions and in the presence of SDAs. Evaporation induced self-assembly (EISA) during coating deposition and the scanning of four types of SDAs have permitted to select the coating that fulfilled specific thickness and refractive index values with, in parallel, excellent results on sol stability. The final optimization has produced mesoporous coatings with ∼9 nm mean pore size, leading to an enhancement in transmittance up to 7.4% over bare glass in the 300–1500 nm wavelength range. The transmittance spectra have been used as inputs for the theoretical calculation of the short-circuit current density of a commercially available multijunction solar cell for CPV applications.

Rapid and real-time diagnosis of hypoalbuminemia using an extraordinary optical transmission biosensor

A hypoalbuminemia diagnosis kit, based on an extraordinary optical transmission sensor, for accurate and fast measurements of albumin concentrations in human serum was demonstrated. First, using nanohole arrays, the sensitivity of the sensor was confirmed to be approximately 460 nm/RIU by theoretical simulations and using standard solutions with specific refractive indices. In the preliminary study of albumin measurements, non-labeled detection of a difference in albumin concentration of approximately 10 mg/ml was achieved with a spectral peak shift of 0.8972 nm and proved to be capable of diagnosing hypoalbuminemia without a surface modification process. Additionally, we successfully classified 100 samples with different concentrations into normal and hypoalbuminemia groups with a probability greater than 98%. According to the results, the hypoalbuminemia diagnosis kit has a potential to be practically employed for real-time, preclinical, label-free diagnosis with integration of advanced microfluidics and miniaturized optics.

Studies on Ethiopian Castor Seed (Ricinus communis L.): Extraction and Characterization of Seed Oil

In this study, Ethiopian castor seeds were collected from a local market and studied for their oil yield and physicochemical characteristics including fatty acid composition. Their oil was extracted using mechanical method and using hexane, ethyl acetate, and methanol solvents and its physicochemical properties were studied. It was done by varying solid-to-solvent ratio (1:9, 1:12 and 1:15) and time (1, 3, 5, 6, and 7 h) for the different solvents used for the extraction. A maximum yield of 72.3% for methanol, 68% for ethyl acetate and 61.6% for hexane was obtained at optimum conditions of 1:12 ratio and 7 h extraction. Specific gravity, viscosity, moisture content, refractive index, acid value, saponification value, iodine value, and peroxide value were measured for the different types of oils. Gas chromatography–mass spectrometry analysis of the four types of oils showed that polar solvents give slightly higher ricinoleic acid content than hexane-extracted oil. Hence, use of polar solvents gave the highest yield, good quality, and purer fatty acid composition for the oil prepared from Ethiopian castor seed, making it suitable for industrial applications due to ease of modification of the chemical structure of the oil.<div><br></div>

Determining the Chemical-Heterogeneity-Corrected Molar Mass Averages and Distribution of Poly(styrene-co-t-butyl methacrylate) Using SEC/MALS/UV/DRI.

Chemical heterogeneity, defined as the change (or lack thereof) across the molar mass distribution (MMD) in the monomeric ratio of a copolymer, can influence processing and end-use properties such as solubility, gas permeation, conductivity, and the energy of interfacial fracture. Given that each parent homopolymer of the copolymer monomeric components has a different specific refractive index increment (∂n/∂c) from the other component, chemical heterogeneity translates into ∂n/∂c heterogeneity. The latter, in turn, affects the accuracy of the molar mass (M) averages and distributions of the copolymers in question. Here, employing size-exclusion chromatography coupled on-line to multi-angle static light scattering, ultraviolet absorption spectroscopy, and differential refractometry detection, the chemical heterogeneity (given as mass percent styrene) was determined for a poly(styrene-co-t-butyl methacrylate) copolymer. Also determined were the chemical-heterogeneity-corrected M averages and MMD of the copolymer. In the present case, the error in molar mass incurred by ignoring the effects of chemical heterogeneity in the M calculations is seen to reach as high as 53,000 g mol-1 at the high end of the MMD. This error could be much higher, however, in copolymers with higher M or with larger difference among component ∂n/∂c values, as compared to the current analyte.

Utilization of Cuttlefish Liver Waste for Oil Production: Evaluation of Quality Characteristics and Biological Activity

The ash, moisture, protein and carbohydrate content of the extracted oil were estimated as 4, 7, 4 and 1% respectively. The Vitamins A and E was found to be 59.14 and 17.4 mg/100 g. Nine fatty acids were found and the Linoleic acid, DHA and EPA were recorded as higher. The specific gravity, solidification point, refractive index, saponification value, iodine value and acid value were also calculated and found as 1.056, 1.2 °C, 1.465 µ, 50.5, 20.4 mg and 0.075 mg KOH/g. The antioxidant activity that includes total antioxidant activity, DPPH & Hydroxyl radical scavenging assay, reducing power and ferrous ion chelating activity of liver oil was studied by following standard methods and results of all the assays was found increasing with increase in concentration. Further purification of liver oil and studying its antioxidant property in animal model shall form the basis for its use as a potent alternate natural antioxidant and nutrition supplements.

Group refractive index quantification using a Fourier domain short coherence Sagnac interferometer.

The group refractive index is important in length calibration of Fourier domain interferometers by transparent transfer standards. We demonstrate accurate group refractive index quantification using a Fourier domain short coherence Sagnac interferometer. Because of a justified linear length calibration function, the calibration constants cancel out in the evaluation of the group refractive index, which is then obtained accurately from two uncalibrated lengths. Measurements of two standard thickness coverslips revealed group indices of 1.5426±0.0042 and 1.5434±0.0046, with accuracies quoted at the 95% confidence level. This agreed with the dispersion data of the coverslip manufacturer and therefore validates our method. Our method provides a sample specific and accurate group refractive index quantification using the same Fourier domain interferometer that is to be calibrated for the length. This reduces significantly the requirements of the calibration transfer standard.

Theoretical and experimental study of mirrorless fiber optics refractometer based on quasi-Gaussian approach

A mirrorless refractometer was studied and analyzed using the quasi-Gaussian beam approach. The Fresnel equation for reflectivity at the interface between two mediums with different refractive indices was used to calculate the directional reflectivity, R. Various liquid samples from 1.3325 to 1.4657 refractive indices units were used. Experimentally, a fiber bundle probe with a concentric configuration of 16 receiving fibers and a single transmitting fiber was employed to verify the developed models. The sensor performance in term of sensitivity, linear range, and resolution, were analyzed and calculated. It has been shown that the developed theoretical models are capable of providing quantitative guidance of the output of the sensor with high accuracy. The highest resolution of the sensor was 4.39 × 10−3 refractive indices units, obtained by correlating the peak voltage along the refractive index. The resolution is sufficient for determining the specific refractive index increment of most polymer solutions, certain proteins, and also in monitoring bacterial growth. The accuracy, simplicity, and effectiveness of the proposed sensor over a long period of time while having non-contact measurements reflect a good potential for commercialization.

Synthesis and characterisation of electro-rheological property of novel eco-friendly rice bran oil and nanofluid

In this study, thermophysical properties: electrical properties, viscosity, refractive index and density of rice bran oil (RBO), RBO added with antioxidants (RBOA), RBOA added with nanoparticle like ZnO and ZnZrO were investigated. Ensuring the quantification of the elements in nanoparticle, morphological study was conducted using SEM (Scanning Electron Microscope). Variation of electrical and rheological properties of base fluid and nanofluid at different temperatures and frequency was investigated. Changes of electrical parameters in the frequency range 1Hz to 10MHz of microwave region was experimented. Using Stokes–Einstein equation: diffusion time and diffusion constant were calculated and the enhancement of viscosity was obseved to vary with agglomeration. In addition specific refractive index, specific polarisation and orientation polarisation of the samples were also estimated. Vicissitudes of electrical parameters and viscosity was experimental with temperature ranging from 303K to 373K. Shear property of the samples were studied on heating and cooling and the results confirms that shear variation does not affect the stability of nanofluid with temperature. In order to validate the results, modeling has been carried out using Arrhenius and Andrades models for the electrical parameters with temperature and for which the regression coefficient R2 is 0.918 to 1.0. The present study helps to use the nanofluid in the appropriate industrial applications.

Determination of length distribution of TEMPO-oxidized cellulose nanofibrils by field-flow fractionation/multi-angle laser-light scattering analysis

Aqueous nanocellulose dispersions were prepared from wood cellulose by 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation. The obtained TEMPO-oxidized cellulose was converted into TEMPO-oxidized cellulose nanofibrils (TOCNs) of different lengths by controlling the nanofibrillation conditions in water or using dilute acid hydrolysis. The average lengths and length distributions of TOCNs have been measured from transmission electron microscopy (TEM) and atomic force microscopy (AFM) images. However, because the number of nanocelluloses observable in TEM and AFM images is limited, a more reliable method is needed to obtain the lengths/length distributions of TOCNs. In this study, the aqueous TOCN dispersions were subjected to a combination of field-flow fractionation (FFF) and multi-angle laser-light scattering (MALLS). The optimum FFF operation conditions for the acid-hydrolyzed TOCN were first established to obtain reasonable data. For TOCNs with average lengths > 400 nm, suitable separation could not be achieved using the FFF/MALLS system. In contrast, the TOCNs with average lengths of 170 and 270 nm were adequately separated according to their sizes by the FFF system. The TOCN length distribution patterns corresponded well to those obtained from TEM images. However, the amounts of TOCNs with lengths > 250 nm were underestimated compared with those determined from TEM images. For TOCNs with average lengths of 170 and 270 nm, the molar mass at each TOCN length was determined using the FFF/MALLS system combined with a refractive index detector, where a specific refractive index increment of 0.165 mL/g was used for TOCN.

用双液芯柱透镜测量蔗糖水溶液的液相扩散系数

Based on the consideration of the high resolution of the spatial resolution of the refractive index of the double liquid-core cylindrical lens(DLCL), the liquid-phase diffusion coefficients of different concentrations of aqueous sucrose solution are measured at room temperature(25℃) using two methods. Method 1:equivalent RI(refractive index) method is used to calculate the liquid phase diffusion coefficient by recording the time-dependent change of a specific refractive index layer during diffusion. Method 2:instantaneous diffusion analytical method is used to determine the liquid diffusion coefficient by reading the relationship between image width and diffusion position in an instantaneous diffusion image. The front liquid core of the DLCL serves as a diffusion cell and a main imaging element, and the rear liquid core serves as an aplanatic auxiliary system. The spherical aberration at a particular thin liquid layer can be reduced as needed with a DLCL, and the spherical aberration advantage within a certain range of refractive index can also be reduced. Both methods have the characteristics of high measurement accuracy. The relative errors between the measured results and the literature values of the two methods are less than 1.3% and 3.9%, respectively, indicating that the measurement system is stable and reliable and the measurement results are accurate when the liquid-phase diffusion coefficient is measured with a DLCL.

Highly improved operation of monolithic BGO-PET blocks

In PET scanners both scintillation crystals and photosensors are key components defining the system's performance and cost. Original PET systems used BGO or NaI(Tl) scintillators but achieved limited performance due to its slow decay and relatively low light output. Moreover, NaI(Tl) has low stopping power for 511 keV annihilation photons. In this study we report the possibility to reintroduce BGO crystals, and in particular in the form of monolithic blocks, especially suitable for low-dose large-size PET scanners, offering significantly improved sensitivity at a highly reduced cost compared to LYSO type fast scintillators. We have studied the performance of a monolithic BGO block as large as 50 × 50 × 15 mm3 with black-painted lateral walls to reduce lights spread, enabling accurate photon depth of interaction (DOI) measurements. A directional optical layer, called retro-reflector, was coupled to the entrance face bouncing back the scintillation light in the direction of the emission source and, therefore, adding to the light signal while preserving the narrow light cone distribution. Four configurations namely 12 × 12 and 16 × 16 SiPM arrays (3 mm × 3 mm each) as photosensors, with or without a nanopattern treatment at the crystal exit face, have been studied. This structure consisted of a thin layer of a specific high refractive index material shaped with a periodic nanopattern, increasing the scintillation light extraction. The readout returned information for each SiPM row and column, characterizing the X-Y light distribution projections. We have studied the detector spatial resolution using collimated 22Na sources at normal incidence. The DOI resolution was evaluated using collimated gamma beams with lateral incidence. The overall best detector performance was obtained for the 16× 16 SiPM array offering higher readout granularity. We have determined the spatial resolution for 3 separated DOI layers, obtaining the best results for the DOI region near to the photosensor.

Plasmonic Beam Deflector and Optical Coupler

A new beam deflector and optical coupler structure based on plasmonic nano-slits is proposed and numerically investigated. The structure consists of periodic nano-slits array with the same width and interval. All nano-slits are etched on a silver film whose dimension D is $7~\mu \text{m}$ (The transverse span of the structure). Arbitrary deflection angle can be selected for reflected light by adjusting the size of the nano-slits, the effective refractive index, and the interval of the nano-slits. This structure also can act as an optical coupler by placing a medium on the top of the nano-slits array with specific size and refractive index. The coupling efficiency can approach to 80.73%, and it provides a promising way to design and manufacture future compact optical communication device.

Determination of molar masses of macromolecules by size exclusion chromatography-light scattering not requiring knowledge of refractive index increments

A new approach for the calibration of SEC-light scattering (SEC-LS) setups is proposed, which requires solely the molar mass of a reference polymer. Neither the specific refractive index increment of the calibrant nor of the analyte is required. Comparison of the molar masses derived in different solvents for a large number of chemically different polymers shows that the new approach yields the same molar masses as if molar masses were derived using dn/dc to calibrate the light scattering setup. The approach therefore allows easier determination of molar masses by SEC-LS.

Switchable Plasmonic Film Using Nanoconfined Liquid Crystals.

Structural coloration using plasmonic particles has received substantial attention due to its robust, permanent, and scalable characteristics across the full color range. In this study, a plasmonic structure based on a porous anodic aluminum oxide (AAO) film coated with a metallic film was fabricated. Colors were varied by changing the refractive index, which was achieved with a convolution with nanopores of AAO film and an infiltrated liquid crystal (LC) material. LC molecules confined in the porous AAO film were uniformly aligned, and they exhibited pore-size-dependent colors because of the specific refractive index. The thermal phase transition of the LC material in the nanopores changed the effective refractive index, switching the reflected colors, and the LC-infiltrated AAO remained stable over a month. We believe LC materials can extend the use of rigid conventional plasmonic structures from simple sensor applications to multifunctional uses such as color printing, writing pens, and displays.

Optimization of biodiesel production from sandbox (Hura crepitans L.) seed oil using two different catalysts

ABSTRACTBiodiesel is a renewable and environmentally friendly fuel used in internal combustion engines. The major challenges in the biodiesel industry are those of food-fuel crisis associated with the use of edible oils for biodiesel production and the type of catalysts used for production. This work focused on the determination of optimal conditions for biodiesel production from inedible sandbox (Hura crepitans L.) seed using calcined snail shell (CSS) and potassium hydroxide (KOH) as catalysts. Oil was extracted from sandbox seeds using solvent extraction. The raw sandbox oil was used for biodiesel production using the transesterification method with KOH and CSS as catalysts. D-optimal design of response surface methodology (RSM) with 24 experimental runs was used to study the optimum yield response of biodiesel using temperature, time, and catalyst concentration as reaction the parameters. Selected fuel properties (specific gravity, viscosity, cloud point, pour point, density, and refractive index) of the ethyl esters were determined according to American Society for Testing Materials (ASTM) standards. The optimum biodiesel yield (93.97%) was obtained at residence time of 1 h 47 min and reaction temperature of 65ºC catalysts concentration (1.5 w/w). All the fuel properties determined fell within the specifications of ASTM standards.