Abstract: In piezoelectric sensors, conventional amplification factor adjustment methods involving the cutting of a wiring pattern or use of a laser trimmable resistor are unable to adjust the amplification factor when the sensor is in a completed state. As a result, the production process becomes complex and production costs increase. Further, because the amplification factor adjustment is carried out in a different state from that of the finished product, the problem that the amplification factor is not set correctly in the finished product also occurs. A non-volatile memory is incorporated in an integrated circuit in which are integrated piezoelectric sensor circuit elements. The amplification factor is adjusted by writing data from a writing terminal to change an amplification resistor.

Abstract: Provided is a pressure sensor apparatus including a lead frame, a pressure sensing element mounted on the lead frame to measure a relative pressure between a first part and a second part, and a housing including a reference medium inlet hole to apply a pressure of a reference medium to the first part, and including a target medium inlet hole to apply a pressure of a target medium to the second part, wherein the reference medium inlet hole is provided in a first surface of the housing, wherein the target medium inlet hole is provided in a second surface of the housing other than the first surface, and wherein the lead frame includes one or more insertion terminals configured to be inserted into and electrically connected to terminal holes of a wire connector.

Abstract: A sensor assembly comprising a housing defining a cavity, and a pressure sensor package arranged within the cavity. The pressure sensor package includes a substrate having an aperture defined therethrough, a semiconductor die including a sensing diaphragm attached to the substrate such that the diaphragm is exposed via the aperture, and at least one electrically conductive element in electrical communication with the semiconductor die arranged on the substrate. A sealing element, such as an elastomeric o-ring, provides a seal between the housing and the substrate. A connector is secured to the housing via a crimped connection for establishing electrical connections between the pressure sensor package and an external system.

Abstract: Aspects of the subject technology relate to electronic devices with pressure sensors. A pressure sensor in a portable electronic device may include an integrated heater or may be co-operated with an external heater for the pressure sensor. The heater may be operated to heat some or all of the pressure sensor for pressure sensor testing, calibration, or temperature-controlled pressure sensing operations.

Abstract: Provided is a sheet sensor comprising an anisotropically-conductive sheet exhibiting conductivity in a thickness direction and having a first surface as a contact surface for a sensing target object, and multiple conductive members electrically connected to a second surface of the anisotropically-conductive sheet and electrically insulated from each other.

Abstract: A pump seal leakage detection system (8) includes a leakage piping (13) including a collector pipe (21) and an air stream pipe (23), a sensor (15) positioned at the air stream pipe (23), and an air displacement device (17) for driving an air stream through the air stream pipe (23). The collector pipe (21) includes an inlet port (25) that is connectable to a leakage centrifuge (5), and an outlet port (27) into the air stream pipe (23). The sensor (15) is configured to detect a leakage drop at the outlet port (27) of the collector pipe (21) or in the air stream pipe (23). The air displacement device (17) is configured to blow a leakage drop off the outlet port (27) of the collector pipe (21) by an air stream towards an outlet port (35) of the air stream pipe (23).

Abstract: Improved gas leak detection from moving platforms is provided. Automatic horizontal spatial scale analysis can be performed in order to distinguish a leak from background levels of the measured gas. Source identification can be provided by using isotopic ratios and/or chemical tracers to distinguish gas leaks from other sources of the measured gas. Multi-point measurements combined with spatial analysis of the multi-point measurement results can provide leak source distance estimates. These methods can be practiced individually or in any combination.

Abstract: A device adapted for installation onto a toilet overflow pipe to indicate a leaking condition of a toilet flush valve. The device having a stem portion with a diameter configured for receipt within an interior diameter of a toilet overflow tube. The device including a housing forming a reservoir for collection of water prior to entering the overflow tube. The reservoir including a cavity for the placement of a water soluble pigment, wherein the pigment is dissolved within water in the housing and into the overflow tube. An alternate embodiment of the device, includes a stay member configured to support a ball float member in an off condition.

Abstract: A testing device for a backflow preventer assembly has a plurality of automated valves. Each automated valve is coupled to a corresponding test valve of the backflow preventer assembly. A high side diverter array is coupled to at least one of the plurality of automated valves. A low side diverter array is coupled to at least one of the plurality of automated valves. A vent side diverter array is coupled to at least one of the plurality of automated valves. A pressure differential transmitter is coupled to the high side diverter array and the low side diverter array. A high side bleed solenoid is coupled to a high side of the pressure differential transmitter. A low side bleed solenoid is coupled to a low side of the pressure differential transmitter. A vent side bleed solenoid coupled to a vent side diverter array. A plurality of bypass solenoids is coupled to the high side bleed solenoid, the low side bleed solenoid and the vent side bleed solenoid.

Abstract: An optical wavefront testing system includes a light source, an image capturing unit and a processing unit. The image capturing unit includes a lens array and a sensor module that is configured to detect light rays passing through an optical element and the lens array. The processing unit controls the sensor module to detect the light rays under a plurality exposure conditions for generating a plurality of images each including a plurality of light spots, obtains a plurality of light spot datasets corresponding to the light spots and each including a plurality of pixel coordinate sets and a plurality of pixel values, and obtains wavefront information associated with the light spots based on the light spot datasets of at least two of the images.

Abstract: A method and system of providing customizable service for an asset. The method including generating a predictive model for each asset of a fleet, each predictive model based on an operational profile for the asset and including a probability density function associated with the operational durability of the asset, establishing a maintenance strategy associated with the asset, and combining each of the predictive models to generate a compound fleet performance model, the fleet performance model including a combined probability density function. The method also includes collecting actual asset performance and maintenance data to generate actual asset metrics, determining a fleet performance profile based on the actual asset metrics indicative of a health assessment of the fleet, comparing the predicted fleet performance with the actual fleet performance, and ascertaining actionable choices for managing the assets based on a deviation of the predicted and actual fleet performance.

Abstract: Rolling resistance is appropriately and easily evaluated at an arbitrary temperature of a tire. When a phase difference between a load applied to the tire and a variation in position of the drum is derived for a reference tire, the phase differences ? are derived at a plurality of temperatures within a range from an initial temperature to an atmospheric temperature in a process in which a temperature of the reference tire that reached the initial temperature higher or lower than the atmospheric temperature by heating or cooling approaches the atmospheric temperature from the initial temperature. The phase difference corresponding to a temperature of a tire to be evaluated among the phase differences ? derived for the reference tire at the plurality of temperatures and the phase difference derived for the tire to be evaluated are compared, thereby evaluating rolling resistance of the tire to be evaluated.

Abstract: Method for checking a tyre. The method includes associating first and second independent light sources with a camera, applying a first force against a first surface portion of the tyre to generate a first deformed surface portion, and illuminating the first deformed surface portion with a first light radiation emitted by the first light source while keeping the second light source deactivated. A first image of the first deformed surface portion is then acquired by the camera. The first force is removed and a second surface portion partially distinct from the first surface portion is illuminated with a second light radiation emitted by the second light source without deforming the second surface portion. A second image of the second surface portion is then acquired by the camera. The first and second images are processed for detection of possible defects in the first and second surface portions.

Abstract: A device abnormality diagnosis method for a device to be diagnosed constituting a plant includes: obtaining time-series data of a plurality of state amounts of the plant which are correlated to an abnormality of the device to be diagnosed; a step of obtaining abnormality diagnosis data on the plurality of state amounts by performing pre-processing on at least one state amount of the plurality of state amounts to exclude, from the time-series data on the state amounts, data of the at least one state amount obtained in an exclusion period which is at least a part of a transient state period during which the device to be diagnosed is affected by a state change of another constituent device of the plant; and a step of performing abnormality diagnosis on the device to be diagnosed on the basis of the abnormality diagnosis data of the plurality of state amounts.

Abstract: Aspects of the disclosure relate to demarcation templates for demarcating a test area on a test surface and for providing visual guidance to a user to precisely and accurately swab the test surface in order to determine the presence and/or concentration of an analyte of interest on the test surface. In one aspect, the analyte of interest is a hazardous contaminant. Some templates can include alignment markings around the border demarcating the test area to provide such guidance to users, and can include graphical use instructions on a removable central portion of the template. The template can be adhesive to be securely fixed to the test surface for accurate demarcation of the test area throughout sampling.

Abstract: Aspects of the disclosure relate to reactive demarcation templates for demarcating a test area on a test surface and for generating a visual indication of chemical properties of the test surface. Some templates can include an indicator portion, or multiple indicator portions, that indicate properties of a sample contacting the template.

Abstract: An automated system for sampling seeds generally includes an automated sampling station having a sampler configured to remove material from a seed while protecting germination viability of the seed, a seed conveyor configured to receive the seed from out of the sampling station after the material is removed from the seed, and a sample conveyor configured to receive the material removed from the seed. The sample conveyor is configured to locate the material removed from the seed in a sample container, and the seed conveyor is configured to locate the seed from which the material is removed in a seed container so as to facilitate a one-to-one correspondence between the seed and the material removed from the seed.

Abstract: A device for black sand collection having a two-piece housing holding a rod with a magnet at an end thereof. A button and coil allow the rod to be depressed such that the magnet is pushed toward an end of the device, allowing the device to magnetically collect black sand. Releasing the button allows the device to release the black sand.

Abstract: A 3D time series vector sediment trap includes a base disposed with trap pipes which includes water flow pipes and sedimentation pipes. The water flow pipes have a horizontal water inlet at the front end, a vertical downward water outlet at the back end and the water flow pipe is internally provided with a filter screen which tilts towards the water inlet. The filter screen is internally tangential to the water flow pipe, and the sedimentation pipes are vertically fixed underneath the water flow pipes. The top end of the sedimentation pipes have an opening and bottom end thereof is closed. The opening is connected to the water flow pipe and directly faces the filter screen so that materials with a diameter greater than the screen pore diameter are intercepted by the filter screen in the water flow pipe and collected in the sedimentation pipe.

Abstract: An aldehyde fixative solution at a first temperature is caused to contact a tissue sample for a first time period, additionally an aldehyde fixative solution is caused to contact the tissue sample at a second temperature higher than the first temperature for a second time period. The first time period typically ranges from about 15 minutes up to about 4 hours, and the first temperature typically is from greater than 0° C. to at least 15° C. The second temperature typically is from greater than about 22° C. to about 55° C., and the second time period ranges from about 1 hour to about 4 hours. Using this process, improved tissue morphology and IHC staining as well as superior preservation of post-translation modification signals have been accomplished in approximately 4 hours compared to 24 hours for room temperature protocols, and more even morphology and antigen preservation are observed.

Abstract: The invention relates to a method for counting cells, such as bacteria and/or somatic cells in liquid samples, such as in dairy products, preferably raw milk. Disclosed is a method comprising a combination of steps that apply dimeric nucleic acid dyes that normally do not penetrate cells (=cell-impermeant dyes), which are rendered cell-permeant by using the right combination of pH, buffer and temperature.

Abstract: The present invention relates to a clearing technique which uses a solution containing at least one of a compound having a delipidation ability, a compound having a biochrome decoloring ability, a compound having a decalcification ability, a compound having a refractive index adjusting ability, and a compound having a tissue swelling ability. The clearing technique is suitable for use in high-throughput and low-magnification imaging which involves a simple process.

Abstract: A slide rack device for slide specimen processing mainly includes a cover plate, a slide, a slide rack, and a spring piece. The slide rack is provided with a plurality of integrated V-shape insertion slots and a spring piece fixedly disposed inside the V-shape insertion slot. The insertion slot is V-shape and provided upright or inclined, and a plurality of slide assemblies which are assembled by a slide specimen to be tested and the slide cover plate can be closely placed in the insertion slot, so that space utilization is greatly enhanced. It is easy and convenient to assemble or disassemble the slide assembly from the insertion slot. The slide rack can endure higher temperature. When a heat treatment is required in the specimen processing, the slide is inserted in the rack, and then a bottom of the slide is immersed in a hot medium for heating.

Abstract: An on-demand vapour generator includes a vapour chamber configured to produce a vapour and a vapour absorption assembly configured to receive flows of vapour from the vapour chamber. The vapour absorption assembly includes a first vapour-permeable passage having a passage outlet and at least one second vapour-permeable passage that is closed. When vapour absorption assembly receives a flow of vapour from the vapour chamber, the flow of vapour passes through the first vapour-permeable passage to the passage outlet at least substantially without absorption of vapour from the flow of vapour. However, when a flow of vapour is not received from the vapour chamber, vapour entering the vapour absorption assembly from the vapour chamber passes into the first vapour-permeable passage and the at least one second vapour-permeable passage and is at least substantially absorbed.

Abstract: Sampling systems and techniques that increase pickup efficiency and shedding efficiency of an analyst of interest collected from a surface are provided. In one aspect, an absorbent swab collects an analyte of interest, such as a hazardous contaminant, from a test area demarcated by a template. The sampling techniques can include swab speed and force protocols specifying how fast and how hard the user should apply the swab across the surface to improve pickup efficiency. The sampling techniques can include instructions for inverting a container enclosing the swab and collected contaminant to improve shedding efficiency from the swab.

Abstract: A method for preparing a protein-containing sample for analysis by mass spectrometry includes introducing the sample into a reaction vessel. The reaction vessel contains a reagent mixture including pre-measured quantities of an immobilized proteolytic enzyme, a reducing agent and an alkylating agent. The contents of the reaction vessel are activated by heating or by sonication.

Abstract: A pair of jigs has the same mass and a weight is adjusted in consideration of a test piece shape so that stress of a center portion of a test piece becomes a desired value. That is, the jig serves as a weight adjustment tool for adjusting a resonance frequency and stress of the test piece. The upper and lower jigs are attached to both ends of the test piece S so that the center of gravity of the upper jig and the center of gravity of the lower jig are located on a perpendicular line passing through the center portion of the test piece.

Abstract: The present disclosure relates to an assessment method for a polyethylene resin, and more specifically to a new assessment method for a polyethylene resin which can accurately determine long-term durability of a molded article by using physical properties that are easily measurable in a short time.

Abstract: A method for testing a helmet for effectiveness of user protection includes moving a load along a predetermined path, supporting a target body at an impact location in the predetermined path, the target body including a head model and a helmet disposed on the head model, and impacting the target body with a force generated by the moving of the load. The impacting of the target body entails contacting the target body with an impactor free to move perpendicularly and tangentially relative to a surface of the target body. The supporting of the target body is at least reduced, if not eliminated, before or during the impact of the impactor with the target body at the location. Forces generated are automatically measured or sensed during the impact of the impactor with the target body at the location.

Abstract: The present invention discloses an experiment device and a method for detecting abrasion of a conveyer. The device comprises a rack, a reciprocation sliding mechanism, a speed adjusting mechanism and a crankshaft, wherein the reciprocation sliding mechanism comprises scrapers and scraper chains; the scraper chains are arranged between an upper-layer scraper and a lower-layer scraper; the speed adjusting mechanism comprises a motor, a friction driving wheel and a friction driven wheel; the motor is connected with the friction driving wheel through a motor shaft; the friction driving wheel slides on a shaft in an axial direction; speed adjustment can be achieved by changing the distance between the centers of the friction driving wheel and the friction driven wheel.

Abstract: Methods, apparatus, and articles of manufacture to multi-purpose an acoustic emission sensor are disclosed. An example apparatus includes a collection engine to obtain a measurement from an acoustic emissions sensor coupled to a fluid flow control assembly, and obtain a state of the fluid flow control assembly. The example apparatus further includes a selector to adjust a gain of a pre-amplifier based on the state to adjust the measurement, and a condition identifier to identify a condition of the fluid flow control assembly based on the adjusted measurement.

Abstract: Nuclear magnetic resonance (NMR) gas isotherm techniques to evaluate wettability of porous media, such as hydrocarbon reservoir rock, can include constructing a NMR gas isotherm curve for a porous media sample gas adsorption under various pressures. A hydrophobic or hydrophilic nature of the porous media sample can be determined using the NMR gas isotherm curves. A wettability of the porous media sample can be determined based on the NMR gas isotherm curve. The wettability can be determined for porous media samples with different pore sizes. In the case of reservoir rock samples, the determined wettability can be used, among other things, to model the hydrocarbon reservoir that includes such rock samples, to simulate fluid flow through such reservoirs, or to model enhanced hydrocarbon recovery from such reservoirs.

Abstract: This application discloses a method of using an apparatus comprising a processor to determine a diffusion coefficient (D) of a solute in a solution flowing in a capillary. The method includes obtaining a first signal comprising a plurality of measurements of solute concentration measured at a first measurement location corresponding with a first mean measurement time that is before a full dispersion condition is met; obtaining a second signal comprising a plurality of measurements of solute concentration measured at a second measurement location corresponding with a second mean measurement time that is after the first mean measurement time and before a full dispersion condition is met; calculating an actual front height ratio; a convection front height ratio; and a proportion of the solute that dispersed between the first mean measurement time and the second mean measurement time.

Abstract: An apparatus of ultrafast particle dynamics measurement based on photon ensemble correlation spectroscopy include steps of: dispersing a particle sample to be detected; establishing a plurality of sampling volumes, and collecting dynamic scattered light signals in parallel; and constructing sample ensembles based on scattered signals of the sampling volumes, analyzing time correlations between the sample ensembles, and detecting particle dynamic characteristics. A period for a single measurement of particles according to the method can be in the range of several milliseconds to several tens of milliseconds, which is conducive to real-time detection. More accurate and reliable correlation characterization can be obtained by combining the detected complex-valued scattered signals with both amplitude and phase information. Furthermore, the particle detection is able to be spatially resolved, so as to achieve spatially resolved particle dynamic characteristics.

Abstract: The invention relates to a method for determining properties of particles in a medium by measuring scattering of a light ray guided through the medium. The light ray (2) can be led through a scattering zone (4) more than once. Both the scattered (5) and unscattered light are measured using the same sensor (6). The invention also relates to a measuring device for measuring the properties of particles in a medium, such as flue gas.

Abstract: Devices, systems, and methods are disclosed for improved laser speckle imaging of samples, such as vascularized tissue, for the determination of the rate of movement of light scattering particles within the sample. The system includes a structure adjoining a light source and a photo-sensitive detector. The structure can be positioned adjacent the sample (e.g., coupled to the sample) and configured to orient the light source and detector relative the sample such that surface reflections, including specular reflections and diffuse reflections, are discouraged from entering the detection field of the detector. The separation distance along the structure between the light source and the detector may further enable selective depth penetration into the sample and biased sampling of multiply scattered photons. The system includes an operably coupled processor programmed to derive contrast metrics from the detector and to relate the contrast metrics to a rate of movement of the light scattering particles.

Abstract: The method includes a counting step of counting, among cells included in a sample, a first cell number indicating the number of cells classified into a first group based on cell size and cell nucleus size and having a DNA amount greater than a threshold value, and a second cell number indicating the number of cells classified into a second group that is different from the first group based on the cell size and cell nucleus size and having a DNA amount greater than the threshold value; and a comparing step of comparing the first cell number with the second cell number.

Abstract: In the particle analyzing apparatus of the present invention, first, an inner space with a negative pressure having a predetermined volume is formed in the cylinder of a syringe device for sucking a sample liquid in the measuring chamber, then, the negative pressure is applied to the measuring chamber, the sample liquid is sucked, and measurement of particle is performed in the measuring flow path. The control device calculates a particle analysis value from the measurement signal obtained by the measurement. The particle analysis value is obtained by the sucking force of the negative pressure and the control device further corrects the particle analysis value based on a standard pressure predetermined for the inner space.

Abstract: Methods of evaluating a cellular sample for HER-2/neu expression are provided. Aspects of the methods include flow cytometrically obtaining fluorescence emission data from a cellular sample fluorescently labelled HER-2/neu specific binding member and employing the sample fluorescence emission data with standard fluorescence emission data to obtain a value of fluorescently labelled HER-2/neu specific binding members bound per cell.

Abstract: Systems and methods for detection of pipe characteristics, such as defect detection of downhole tubulars and overall thickness estimation of downhole tubulars (e.g., pipes such as casing and/or production tubing).

Abstract: Systems and methods for corrosion detection of downhole tubulars.

Abstract: A sensor for isolating, identifying, and quantifying one or more analytes in a sample is provided, the sensor having a metal substrate base and a polymer waveguide disposed on the metal substrate base, the polymer waveguide including an optical channel and a polymer disposed in the optical channel; wherein the polymer waveguide optically couples a first and a second fiber optic cable. Also provided herein are methods of using the sensor for isolating, identifying, and quantifying one or more analytes in a sample, the method including contacting the polymer waveguide with a sample, sequentially heating the sensor to a plurality of temperature thresholds, obtaining an optical output at each temperature threshold, and analyzing differences in sequentially-obtained optical outputs in order to identify and determine concentrations of individual analytes of interest in the sample.

Abstract: Provided is a surface condition monitoring apparatus including: a transparent member; a transmission unit including a transmitter that transmits electromagnetic waves from one side of the transparent member toward the other side; and a reception unit including a receiver that detects the electromagnetic waves that enter the one side of the transparent member from the other side, the transmission unit and the reception unit being arranged such that the receiver detects scattered waves of the electromagnetic waves transmitted from the transmitter, that enter the one side from the other side, the transmission unit being configured to be capable of transmitting a plurality of electromagnetic waves having different wavelengths, and the reception unit being configured to detect intensities of the scattered waves of the electromagnetic waves at different positions.

Abstract: Provided herein are systems, devices and methods for performing multianalyte detection in a biological sample, such as a human blood sample. Multiwell plates useful for performing multianalyte detection are also provided. The systems, devices and methods provided herein relate to the field of direct-to-consumer diagnostics (DTC diagnostics) and are useful, e.g., for facilitating consumer access to consumer healthcare and consumer wellness information. Other uses of the systems, devices and methods provided herein relate to the fields of medical research and drug discovery.

Abstract: A method and apparatus for the detection of Acrylamide precursors in raw potatoes including: illuminating at least one region of a raw potato's surface with an illumination beam; measuring the intensity of light scattered by the potato; generating a detection signal based on the measured intensity of scattered light; comparing the detection signal to a predefined threshold; and classifying the potato as having a high Acrylamide precursor concentration if the detection signal exceeds the predefined threshold.

Abstract: The present application provides a medicine monitoring device, system and method. The medicine monitoring device comprises: a medicine analyzer configured to detect a type parameter and an amount parameter of a medicine; and a processing module circuit coupled to the medicine analyzer. The processing module circuit is configured to determine a detected type and amount of the medicine based on the detected type parameter and amount parameter of the medicine, obtain preset type and amount of the medicine, and judge whether the detected type and amount of the medicine coincide with the preset type and amount of the medicine.

Abstract: A molecular detection apparatus, comprising: a chamber; a light source provided in the chamber and configured to emit light; a detector including at least one sensor and configured to generate a first detection data and a second detection data, the sensor being provided in the chamber and being configured to capture molecules of target molecules, the first detection data corresponding to the number of captured molecules per predetermined time under a first emission condition of the light, and the second detection data corresponding to the number of captured molecules per predetermined time under a second emission condition of the light; and a discriminator to discriminate the target molecules using the first and second detection data.

Abstract: A gas inlet system for an isotope ratio spectrometer and a method for coupling analyte gas to an isotope ratio spectrometer are disclosed. A variable volume reservoir is located between a supply of analyte gas and a spectrometer. The reservoir's internal volume is controllably adjusted at a pre-determined rate to generate a defined flow of analyte gas or mixture to or from the reservoir. Analyte gas and carrier gas are taken up by the reservoir on increasing the reservoir's internal volume and then expelled from the reservoir to the spectrometer on decreasing the reservoir's internal volume. An open split can be used together with the reservoir to facilitate splitting away and hence dilution of analyte within the reservoir. A method for cleaning the gas inlet system is provided, which involves flushing the system with carrier gas.

Abstract: Apparatuses, methods, and systems for detecting a substance are disclosed. One system includes a light source, an optical cavity, a cavity detector, and a processor. The light source generates a beam of electro-magnetic radiation, wherein a wavelength of the beam of electro-magnetic radiation is tuned to operate at multiple wavelengths. The optical cavity receives the beam of electro-magnetic radiation, wherein the physical characteristics of the cavity define a plurality of allowed axial-plus-transverse electro-magnetic radiation modes, wherein only a subset of the allowed axial-plus-transverse electro-magnetic radiation modes are excited when the optical cavity receives the beam of electro-magnetic radiation. The cavity detector senses electro-magnetic radiation emanating from the optical cavity.

Abstract: Various embodiments may provide an optical system for determining a refractive index of a sample. The optical system may include a laser source configured to emit a laser beam, and a non-linear crystal configured to generate, based on the laser beam, an infrared light beam which passes through the sample, and a visible signal light beam. The optical system may further include a first mirror configured to reflect the visible signal light beam, a second mirror configured to reflect the infrared light beam so that the reflected infrared light beam interacts with the reflected visible signal light beam in the non-linear crystal, and a photodetector configured to determine a property of the reflected visible signal light beam which has interacted with the reflected infrared light beam for determining the refractive index of the sample.