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New series of polymerizable liquid crystals based on bistolane core and different lateral substituent groups were synthesized and characterized by 1 H‐NMR. The properties of these compounds were tested by DSC, POM and Abbe refractometer. The results indicate that all of these compounds display stable nematic phase, and the introduction of lateral substituents has a significant impact on the phase behaviour and birefringence. These newly compounds present higher birefringence (0.36~0.49) than that of the commercial compounds RM257 because of the extended π‐ conjugated. [ABSTRACT FROM AUTHOR]

Background: Refractometry is used to assess transfer of passive immunity (TPI), but studies evaluating different refractometers and appropriate thresholds for recommended target immunoglobulin G (IgG) concentrations for beef calves are limited. Objectives: To evaluate test performance of digital (DSTP) and optical (OSTP) serum total protein (STP) refractometers and a digital Brix (DBRIX) refractometer for assessment of passive immunity in beef calves. Animals A total of 398 beef calves from 6 herds, 1 to 7 days of age. Methods: Serum IgG concentration was estimated by DSTP, OSTP, and DBRIX, and measured by radial immunodiffusion (RID). Correlation coefficients (r) among results were calculated. Optimal STP and Brix thresholds for identification of IgG <10, <16, and <24 g/L were determined using interval likelihood ratios. Refractometer performance and agreement were assessed using areas under the curve (AUC), diagnostic test characteristics, Cohen's kappa (κ), and Bland‐Altman analysis. Results: Refractometer results were highly correlated with RID (r = 0.82‐0.91) and with each other (r = 0.91‐0.95), and overall test performance was excellent (AUC = 0.93‐0.99). The STP concentrations of ≤5.1, ≤5.1, and ≤5.7 g/dL and Brix percentages of ≤7.9%, ≤8.3%, and ≤8.7% indicated IgG concentrations <10, <16, and <24 g/L, respectively. Agreement of refractometers with RID was variable (κ = 0.46‐0.80) and among refractometers was substantial (κ = 0.62‐0.89). Conclusions and Clinical Importance: All refractometers showed good utility as monitoring tools for assessment of TPI in beef calves. [ABSTRACT FROM AUTHOR]

Background: Veterinary facilities might use multiple refractometers and individuals to measure urine specific gravity (USG). Previous comparison studies show conflicting results. Furthermore, the clinical significance of measurement differences and interobserver variabilities has not been assessed. Objectives: We aimed to determine statistically and clinically significant differences between four refractometers in measuring canine USG and subsequent categorization of urine concentrations and azotemia and determine the variability between different observers performing USG measurements. Methods: Fifty‐nine specimens were included for the USG measurements with four refractometers by different observers. Each refractometer pair was compared using Spearman's rank correlation, Bland‐Altman difference plots, and Deming regression analyses. Calculated bias was compared to set performance goals. Interobserver agreement was evaluated, and intraclass correlation coefficients were used to determine differences in the categorization of urine concentrations and azotemia (prerenal or renal). Results: There was excellent correlation (rs =.99‐1.00) between refractometers. All comparisons involving R4 showed significant constant and proportional biases. Mean bias met the clinical performance goals for all refractometers, except for comparisons with R4, where up to 17 results were outside the allowable bias. There was almost perfect agreement (rs =.999) between observers and excellent agreement (ICC =.96‐.99) for the classification of urine concentrations. In azotemic patients (22%), there was perfect agreement (ICC = 1.00) for the categorization of azotemia. Conclusions: In most cases, three of the refractometers evaluated in this study can be used interchangeably at all USG values, without affecting clinical decision‐making. Multiple observers did not significantly affect decision‐making. [ABSTRACT FROM AUTHOR]

Background: Refractometry is often used in clinical veterinary medicine to estimate urine concentration. Variability among commonly‐used refractometers has not been critically evaluated. Objective: This study aimed to evaluate the variability of urine specific gravity (USG) among four refractometers and compare results of USG measurements with those of urine osmolality (Uosm), the gold standard for determining urine concentrations. Methods: USG was determined in 100 dogs using three optical refractometers, the American Optical Abbe refractometer 10450, Reichert TS 400 refractometer, and Heska Veterinary refractometer 2737‐E02, and one digital refractometer, the Misco Palm Abbe Digital refractometer #PA203. Results were compared between each pair of refractometers and between each refractometer and urine osmolality determined by freezing point depression using a Multi‐Osmette 2430E osmometer. Results were analyzed with Bland‐Altman plots and Passing‐Bablok regression analysis. Results: The Reichert, Heska, and Misco refractometers provide USG measurements that can be used interchangeably based on small differences, consistently less than 0.002, between the USG measurements. The AO refractometer measured USG values with much larger differences, which were deemed clinically significant by the study parameters. None of the refractometers were able to accurately predict Uosm or vice versa within a clinically acceptable range. Conclusions: Varying degrees of differences were seen in the USG measurements among the different refractometers. These differences were refractometer‐dependent, and the results from one instrument could affect clinical decisions. [ABSTRACT FROM AUTHOR]

Summary: Sugar concentration in floral nectars is an assessment required in several diverse fields of application. The widely used analysis, consisting of nectar extraction with a microcapillary and sugar concentration measurement with a light refractometer, is not reliable when the nectar is secreted in small quantities, unextractable with a microcapillary. Ancillary methods adopted in such cases are destructive, rather complicated and often provide much less precise and accurate results.The microscopic‐size, low cost and biocompatibility of optical fibers were exploited to deliver light directly inside the flower with minimal invasiveness and measure instantaneously the refractometric properties of the nectar without extracting it. After comparing the new and old methods using two known nectariferous species, the new approach was validated on Primula palinuri, whose nectar is unextractable with microcapillaries.The fiber‐optic probe was able to measure the nectar refractive index in P. palinuri flowers making it possible to highlight a previously undetected significant trend of the sugar concentration throughout the long anthesis of the single flowers. Changes in nectar concentrations are similar in both longistylous and brevistylous flowers.The fiber‐optic refractometer is an advancement of light refractometer analysis. Further customization of the laboratory set‐up into portable equipment will boost applications. [ABSTRACT FROM AUTHOR]

Background: Urine concentration (UC) provides clinically useful information concerning hydration status and renal function of animals. Objectives: To characterize the clinical performance of urine specific gravity measured by optical refractometry (USG‐R) or Multistix‐SG urine reagent dipstick (USG‐D), urine electrical conductivity using an OAKTON Con 6 conductivity handheld meter (UEC), urine color (UColor) using a custom‐designed 8‐point color chart, and urine creatinine concentration (UCreat) for assessing UC in dairy cattle. Animals: 20 periparturient Holstein‐Friesian cows. Methods: Urine was obtained by perineal stimulation or urethral catheterization and urine osmolality (UOsm, reference method), USG‐R, USG‐D, UEC, UColor, and UCreat determined. Diagnostic test performance was evaluated using Spearman's rho and logistic regression to determine the area under the receiver operating curve (AUC) and optimal cut point for diagnosing hypohydration (UOsm ≥800 mOsm/kg). P < .05 was considered significant. Results: The best performing test for diagnosing hypohydration was USG‐R (AUC = 0.90) at an optimal cut point ≥1.030. The second‐best performing test was UEC (AUC = 0.82) at a cut point of ≥23.7 mS/cm, followed by UCreat (AUC = 0.76) at a cut point of ≥95.3 mg/dL, and UColor (AUC = 0.74) at a cut point of ≥4 on an 8‐point scale. Urine specific gravity measured by dipstick performed poorly (AUC = 0.63). Conclusions and Clinical Importance: USG‐R and UEC provide practical and sufficiently accurate methods for measuring UC in dairy cattle. Urine color had moderate clinical utility as a no‐cost cow‐side method for assessing UC, whereas dipstick refractometry is not recommended for assessing UC. [ABSTRACT FROM AUTHOR]

ABSTRACT: In this study, halogen‐free flame retardant tri(acryloyloxyethyl) phosphate (TAEP) was prepared using 2‐hydroxyethyl acrylate and phosphorus oxychloride. The chemical structure of TAEP was characterized by Fourier transform infrared and proton nuclear magnetic resonance spectrometers. The mixture of TAEP, acrylamide, and pentaerythritol tetrathioglycolate with different P, N, and S content were used to prepare flame retarding optical resin via the click chemistry curing. The curing performance, thermal stability, and flame retardant performance of the optical resins were measured by differential scanning calorimeter, thermogravimetric analyzer, vertical burning tester, and limiting oxygen index test, respectively. Additionally, the morphology of the burned residual was investigated by scanning electronic microscopy, and the refractive indices of the optical resins were measured by an Abbe Refractometer. The results strongly indicated that increasing sulfur content in resins improved their refractive indices, but deteriorated their flame retardancy. Meanwhile, the nitrogen element was helpful for the flame retardancy of the optical resin. With S N, and P contents of 3.00%, 1.00%, and 6.70 wt %, respectively, the refractive index of the optical resin reached up to 1.4987, and its flame retardancy achieved the UL‐94 V‐0 level and the LOI value of 29.3%. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46648. [ABSTRACT FROM AUTHOR]

Purpose: The evaluation of visual acuity (VA) and refraction in the Northern Finland Birth Cohort Eye study was performed using the Nidek AR‐360A autorefractometer. The accuracy of the method for this population‐based screening study was assessed. Methods: Measurements of the refractive error were obtained from the right eyes of 1238 subjects (mean age 47), first objectively with the AR‐360A and then subjectively by an optometrist. Agreement with the subjective refraction was calculated for sphere, cylinder, mean spherical equivalent (MSE), cylindrical vectors J45 and J0 and presbyopic correction (add). Visual acuity (VA) was measured using an ETDRS chart and the autorefractometer. Results: The refractive error measured with the AR‐360A was higher than the subjective refraction performed by the optometrist for sphere (0.007 D ± 0.24 D p = 0.30) and also for cylinder (−0.16 D ± 0.20 D p < 0.0005). The bias between the measurements of MSE, J45 and J0 was low: −0.07 D ± 0.22 D (p = 0.002), 0.01 D ± 0.43 D (p = 0.25) and −0.01 D ± 0.42 D (p = 0.43), respectively. The amount of add measured by the autorefractometer was higher than the subjective 0.35 D ± 0.29 D (p < 0.0005). There was a statistically significant correlation between VA (p < 0.0005) and the difference between the subjective and objective refraction. In 99.2% of the measurements, visual values were within one decimal line of each other. Conclusion: The Nidek AR‐360A autorefractometer is an accurate tool for determining the refraction and VA in a clinical screening trial. [ABSTRACT FROM AUTHOR]

Background: Heat‐treatment of colostrum is a method developed to reduce calf exposure to pathogens. Infrared (IR) spectroscopy and Brix refractometers can be used for measuring colostral IgG concentration and assessing colostrum quality. Objectives: To determine the impact of heat‐treatment on accuracy of IR spectroscopy and Brix refractometers for measuring colostral IgG concentration and assessing colostrum quality before and after heat‐treatment. Animals: A total of 60 Holstein dairy cows on 8 commercial dairy farms. Methods: A cross‐sectional study was designed to determine the effect of heat‐treatment at 60°C and 63°C each for 30 and 60 minutes duration on colostral IgG concentration measured by the reference radial immunodiffusion (RID) assay, IR spectroscopy, and digital and optical refractometers. Results: Colostrum IgG concentration significantly decreased after heat‐treatment at 63°C for 30 or 60 minutes as measured by RID, but the IgG values remained unchanged when measured by IR spectroscopy and refractometers. The lowest correlation coefficient found between IR spectroscopy (r = 0.70) and RID results was in colostrum heat‐treated at 63°C for 60 minutes. For digital (r = 0.48) and optical (r = 0.50) refractometers, the lowest correlation coefficient was at 63°C for 30 minutes when compared to RID. The accuracy of the IR spectroscopy, digital and optical Brix refractometers was decreased from 91.7 to 80%, 81.7 to 45%, and 80 to 45%, respectively, when colostrum heat‐treated at 63°C for 60 minutes. Conclusions and Clinical Importance: Radial immunodiffusion, IR spectroscopy, and Brix refractometers exhibit utility for measuring IgG concentration when colostrum heat‐treated at 60°C but does not detect decrease IgG concentrations when heat‐treated at 63°C. [ABSTRACT FROM AUTHOR]

X-ray mirrors are widely used at synchrotron radiation sources for focusing X-rays into focal spots of size less than 1 µm. The ability of the beamline optics to change the size of this spot over a range up to tens of micrometres can be an advantage for many experiments such as X-ray microprobe and X-ray diffraction from micrometre-scale crystals. It is a requirement that the beam size change should be reproducible and it is often essential that the change should be rapid, for example taking less than 1 s, in order to allow high data collection rates at modern X-ray sources. In order to provide a controlled broadening of the focused spot of an X-ray mirror, a series of refractive optical elements have been fabricated and installed immediately before the mirror. By translation, a new refractive element is moved into the X-ray beam allowing a variation in the size of the focal spot in the focusing direction. Measurements using a set of prefabricated refractive structures with a test mirror showed that the focused beam size could be varied from less than 1 µm to over 10 µm for X-rays in the energy range 10-20 keV. As the optics is in-line with the X-ray beam, there is no effect on the centroid position of the focus. Accurate positioning of the refractive optics ensures reproducibility in the focused beam profile and no additional re-alignment of the optics is required. [ABSTRACT FROM AUTHOR]

ABSTRACT We present a high-sensitivity refractive-index sensor based on etched thin-core fiber (TCF) modal interferometer. The sensor structure is formed by splicing a TCF between two single-mode fibers. To enhance the sensitivity, the thickness of the cladding of sensing region is reduced by hydrofluoric etching. The sensors with different diameters are investigated, and the maximum sensitivity of this new structure is 512nm/R.I.U with fiber diameters of 60 um, which is 4 times higher than that of the basic structure without etching. This structure shows the merits of high sensitivity, low cost, easy control, simplicity of fabrication, and high repeatability. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:53-56, 2017 [ABSTRACT FROM AUTHOR]

The best instrument to measure the refractive index of liquids is the Abbe refractometer which can only provide accuracies of the order of 10−5 at visible wavelengths and 10−4 in the near infrared. Here we present a technique by which the exact wavelength positions in the near infrared frequency comb of a tilted grating inscribed in the core of an optical fiber can be used to measure the absolute value of the refractive index of a liquid in which the fiber is inserted, with an accuracy of ±5×10−5. This is in contrast to typical fiber optic-based 'refractometry' where only refractive index variations can be measured accurately, hence the appellation of 'true' fiber optic refractometer here. In addition to the increased accuracy, the fiber refractometer proposed here offers the additional advantages associated with in situ measurements. The performance of this refractometer is demonstrated by measurements in water from room temperature down to near freezing at wavelengths in the 1550 nm window. [ABSTRACT FROM AUTHOR]

A table of contents for the issue is presented featuring topics optical nanoantennas, optic refractometer and photons.

Nondestructive sugar content analysis of fruits is important for effective quality monitoring during growing stages, postharvest storage, and distribution in markets. The requirement of nondestructive analysis can be satisfied by an optical spectroscopic technique with an appropriate data analysis approach. We applied near-infrared ( NIR) diffuse-reflectance spectroscopy in combination with multivariate calibration as the nondestructive method of sugar content analysis for Korean pears. The diffuse-reflectance spectra for 21 Korean pears with the sugar contents of 10.3−12.9 °Bx were obtained in the wavelength region between 900 and 1500 nm. The differential spectrum of the pear samples with the maximum and minimum sugar contents was found to show structures similar to those of the transmittance spectrum of an aqueous solution of glucose. This confirms that the NIR spectra of pears convey the quantitative chemical information of sugar molecules. A simple, effective spectral intensity normalization method was applied to improve the analysis precision. Based on the normalized NIR spectra, a multivariate calibration model was developed using partial least squares regression for predicting the sugar content of the Korean pear samples. The prediction accuracy was evaluated to be ~0.24 °Bx by the test set switch method. [ABSTRACT FROM AUTHOR]

Background Failure of transfer of passive immunity ( FTPI) is the underlying predisposing risk factor for most early losses in dairy calves. Refractometers, either optical or digital, can be used to assess FTPI as a part of calf health monitoring program on dairy operations. Objectives To evaluate the performance of and differences between digital Brix and optical refractometers for assessing FTPI in dairy calves. Animals Two hundred Holstein calves from 1 to 11 days of age. Methods A cross-sectional study was designed to measure serum Ig G concentration by radial immunodiffusion ( RID) assay, digital Brix and optical refractometers. The correlation coefficients ( r) between the 2 refractometers were plotted against each other and against the measured Ig G concentration from RID. The Se, Sp, and accuracy of digital Brix and optical refractometers for assessing FTPI using previously recommended cut-offs were calculated. A receiver operating characteristic curve was created and used to identify the optimal cut-off for this dataset. Results The RID Ig G concentration was positively correlated with digital Brix ( r = 0.79) and optical ( r = 0.74) refractometers. The best combination of Se (85.5%), Sp (82.8%), and accuracy (83.5%) of digital Brix refractometer was at 8.3% Brix. For optical refractometer, the best combination of Se (80%), Sp (80.7%), and accuracy (80.5%) was at 5.5 g/dL. Conclusions and Clinical Importance Both refractometers exhibited utility in assessing FTPI in dairy calves. [ABSTRACT FROM AUTHOR]

CO2 capture is still a major challenge for the environment and decarbonization of gas streams. It has been industrially feasible for several decades using chemical absorption by alkanolamine solvents. The purpose of this work is to characterize the mass transfer in a spray contactor during CO2 absorption using monoethanolamine as a solvent. A new, effective way to investigate mass transfer is to measure the refractive index during the reactive absorption. Indeed, the concentration and temperature evolution inside the droplet during absorption induces a modification of the refractive index. By using rainbow refractometry technique (GRT), the liquid side mass transfer coefficient was measured in a controlled gas atmosphere during a transfer process in aqueous 30 % (w/w) monoethanolamine and compared to the literature. [ABSTRACT FROM AUTHOR]

Objectives To investigate the accuracy of both the optical and digital Brix refractometers compared with radial immunodiffusion ( RID) for determining the immunoglobulin G ( IgG) concentrations in dairy calf serum. Design The experiment design was a cross-sectional survey of four dairy farms. Serum was sampled from 12 calves from each farm at approximately 48 hours of age. Methods Serum IgG concentrations of 48 calves were measured using RID and both types of Brix refractometer. Results IgG concentrations measured by Brix refractometer scores correlated with RID results: 0.74 and 0.71 for the digital and optical devices, respectively. The minimum Brix score that identified calf serum with success of passive immunity (>1000 mg/dL RID IgG) with 100% accuracy was 10% for both devices. The optical and digital devices performed similarly at identifying IgG concentrations in calf serum, with a concordance of 87%. Conclusion Brix refractometer score ≥10% can be used to classify calves with successful transfer of passive immunity and the devices are sufficiently accurate for use as a simple, inexpensive on-farm tool for the monitoring of neonatal dairy calf immunity levels. [ABSTRACT FROM AUTHOR]

In observing the stereoscopic display at the viewing distance of 1 m, the amount of the perceived depth was determined by the positions of the crossing point that the viewing direction of two eyes intersect. The positions of the crossing points of stereoscopic stimuli were controlled, and the accommodation was measured by the autorefractometer for the seven participants. Accommodation was also measured when viewing the real film chart which was placed at the same position as these crossing points. The accommodation change when viewing the stereoscopic display was measured to be noticeable only when the crossing point was quite near the participant, but this change was still much smaller compared with the accommodation change when viewing the real film chart. This change in accommodation implies the possible occurrence of fatigue related to the accommodation-convergence conflict, while the constant accommodation within the range of DOF implies no conflict between the accommodation and convergence. This measurement scheme may be used to define the range of DOF where the accommodation remains little changed, and thus define the depth of the 3D object at which no accommodation-convergence conflict occurs, for a given stereoscopic display. [ABSTRACT FROM AUTHOR]

This study proposes a novel optical sensor structure based on a refractometer combining a bend waveguide with an air trench. The optical sensor is a 1 × 2 splitter structure with a reference channel and a sensing channel. The reference channel has a straight waveguide. The sensing channel consists of a U-bend waveguide connecting four C-bends, and a trench structure to partially expose the core layer. The U-bend waveguide consists of one C-bend with the maximum optical loss and three C-bends with minimum losses. A trench provides a quantitative measurement environment and is aligned with the sidewall of the C-bend having the maximum loss. The intensity of the output power depends on the change in the refractive index of the measured material. The insertion loss of the proposed optical sensor changes from 3.7 dB to 59.1 dB when the refractive index changes from 1.3852 to 1.4452. [ABSTRACT FROM AUTHOR]

A 10-year-old spayed female Miniature Poodle was presented to the University of Georgia veterinary teaching hospital for evaluation of lethargy, vomiting and anorexia of 4 days' duration. Physical examination, history and a minimum database led to a diagnosis of immune-mediated hemolytic anemia accompanied by marked hyperbilirubinemia. Refractometric protein determination was within the reference interval, whereas the biuret method indicated hypoproteinemia. This discrepancy was attributed to interference of bilirubin and biliverdin with the spectrophotometric read-out of the biuret total protein assay. The albumin concentration, determined by bromcresol green, and refractometric total protein were less affected by this interference. [ABSTRACT FROM AUTHOR]

An high resolution optical technique based on the film fiber optic refractometer has been used to investigate the effect of the thickness on the glass transition dynamic of Atactic Polystyrene films in the range 20-120 nm. The thermo-optic behavior of a set of layers dip coated onto the fiber has been analyzed upon cooling from long term equilibrated melt state. The glassy transition temperature is observed to be thickness-independent as did both the width and the lower and upper bounds of the transition itself. At lowering the thickness of the film the relevant effect is the reduction of the 'contrast' between the melt equilibrium phase and the glassy state. A double layers model where a surface soft layer (3.9 nm at 418 K) do not contribute to the glass dynamic retaining liquid features even at temperature well below the glass transition, while the core layer shows a bulk glass transition, is able to quantitatively reproduce reflectance experimental data. [ABSTRACT FROM AUTHOR]

Background The performance of a digital Atago PAL- USG Cat refractometer (Atago) was compared with a Schmidt and Haensch, Goldberg type refractometer (S+H). Materials and Methods Specific gravity of 47 canine and feline urine samples was determined with both refractometers and the results were compared with Passing-Bablok and Bland-Altman plots. In addition, the specific gravity of dilutions of 10% glucose, 10% NaCl, and 3% albumin solutions was determined and compared with expected values. Results Both refractometers consistently reported 1.000 with distilled water. The correlation between both refractometers based on Passing-Bablok plots of 47 urine samples was excellent ( r = .99), but, in the Bland-Altman plots, there was a significant, proportional, negative error for the Atago readouts. This was also illustrated by the fact that 10 urine samples with an S+H result of > 1.030 were read out between 1.023 and 1.028 by Atago. Schmidt and Haensch results of various glucose solutions matched exactly expected values, but Atago results were lower. Likewise, S+H results with diluted NaCl solutions were closer to expected results than Atago results. In contrast, Atago results with dilutions of 3% albumin were closer to expected results than S+H results. Discussion The Atago refractometer reported lower specific gravity results in urine and standard solutions of glucose and NaCl, which could adversely affect clinical decisions concerning normal renal function based on solute concentrations determined in canine and feline urine samples. [ABSTRACT FROM AUTHOR]

The cure monitoring of composite parts is an important key to optimize the industrial curing cycles. In this study, it is proposed to monitor the cure of a thermosetting resin by a Fresnel refractometer. The measurements are first compared to dielectric analyses and predictions of a thermo-kinetic model that uses parameters from the literature. Under isothermal conditions, the results show that the Fresnel power can be directly exploited to obtain qualitatively the degree of conversion. This is also demonstrated in anisothermal conditions by correcting the Fresnel signal from its temperature dependence. If the initial degree of conversion is known, its quantitative assessment is achieved using the Fresnel and temperature measurements. POLYM. ENG. SCI., 54:626-635, 2014. © 2013 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

ABSTRACT This article presents a systematic strategy for formulation and optimization of thermotropic layers for overheating protection purposes. Specifically, thermotropic systems with fixed domains (TSFD) which consist of a thermotropic additive finely dispersed in a matrix material are considered. Based on systematic material (component) preselection regarding thermoanalytical characteristics and refractive indices, numerous thermotropic layers were formulated. TSFD with thermoplastic matrix were produced by compounding and compression molding. TSFD with resin matrix were produced by UV curing. The thermotropic layers were analyzed as to solar optical properties, threshold temperature, switching process and residual transmittance in the opaque state applying UV/Vis/NIR spectrometry equipped with a heating stage. Best performing materials exhibited solar hemispheric transmittance in the range of 72.2-84.5% and between 59.6 and 83.7% in the clear and opaque state, respectively. Threshold temperatures between 45 and 75°C were realized. Refractive index difference between matrix and additive and solar hemispheric transmittance displayed a close correlation. Hence, refractometry was shown to be an appropriate tool for material preselection. Furthermore, investigations revealed a close correlation of thermal transitions of thermotropic additives recorded by differential scanning calorimetry and threshold temperatures of thermotropic layers formulated therewith. However, thermotropic layers formulated so far have to be optimized with respect to light-shielding performance for efficient overheating protection. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39950. [ABSTRACT FROM AUTHOR]

This study presents a microcontroller‐based instrumentation system to measure the refractive index (RI) of an unknown liquid using an optical fibre sensor probe. A bare, tapered and bent multi‐mode optical fibre (BTBMOF) is used as the sensing element or refractometer to construct an optical fibre sensor probe. The optical fibre sensor probe contains (i) a diode laser as source (with a pigtail), (ii) a BTBMOF as sensing element and (iii) an LDR (light dependent resistor) as detector. The bare and tapered portion of the optical fibre sensor is given the shape of a semicircular arc to add the macro bending effect along with the power coupling effect (which takes place because of propagation of a light ray through the tapered portion of the fibre). The diode laser source launches a beam of laser ray at one end of the BTBMOF. The power transmitted through the BTBMOF is influenced by the RI of the liquid surrounding it. The laser beam coming out from the BTBMOF is made incident on the LDR. Thus, the resistance of the LDR changes according to the RI of the liquid applied around the BTBMOF. The LDR is connected across a 5 V DC supply with a series resistance to form a potential divider circuit. The output from the potential divider circuit is interfaced to the ADC0 (analogue input pin) of an ATmega 32 microcontroller via a low‐pass filter for reading and displaying the RI value of the liquid. [ABSTRACT FROM AUTHOR]

. Purpose: To evaluate the clinical usefulness of a new rebound tonometer, Icare® PRO (Icare PRO), by comparison with Goldmann applanation tonometry (GAT) in a study on patients with glaucoma. Methods: One hundred and seventy-two eyes of 86 subjects were enrolled in this study. All of the subjects were examined with an autorefractometer, Icare PRO, slit-lamp biomicroscope, GAT, ultrasound A-scan and pachymeter. Three intraocular pressure (IOP) measurements were obtained by Icare PRO and GAT. The intraobserver reliabilities were established by calculating the intraclass correlation coefficients. The Bland-Altman plot was used to compare the Icare PRO and GAT. Results: There was a good correlation between the IOP measurement by GAT and that by Icare PRO ( r = 0.6995, p < 0.001). The intraclass correlation coefficients of Icare PRO and GAT were 0.778 and 0.955, respectively. The IOP differences between Icare PRO and GAT (mean: 1.92 mmHg; SD: 3.29 mmHg; 95% limit of agreement: −4.52 to 8.37 mmHg) did not vary over the wide range of central corneal thickness (p = 0.498), age (p = 0.248), axial length (p = 0.277) or spherical equivalent (p = 0.075). Conclusions: Although IOP with Icare PRO was higher than that with GAT, especially at lower GAT IOP value, Icare PRO was found to be a reliable method and showed a good correlation with GAT. The IOP difference between Icare PRO and GAT was not affected by the central corneal thickness, age, axial length or spherical equivalent. Icare PRO can be expected not only to be a good screening tool but also to be a good substitute for GAT. [ABSTRACT FROM AUTHOR]

Poly(methyl methacrylate), which is prepared by polymerization of methyl methacrylate (MMA), is widely used in the fabrication of polymer optical fiber and devices. In this article, a dielectric measurement method was proposed to monitor the polymerization process. The measurement result is compared with that obtained by the traditional Abbe's refractometer method. By monitoring the dielectric behaviors of polymerization system, the correlation between dielectric properties of reacting bulk and conversion of MMA was established. The influence of reactive temperature, reactive time, conversion rate of prepolymerization, and oxygen environment was discussed. It was shown that the gel effect occurred at 2 h at the reactive temperature of 50°C when the conversion of prepolymer was about 24% with the absence of oxygen. The conversion rate obtained by Abbe's refractometer method was larger than that measured by dielectric method in the reaction metaphase. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

We analyze viewing region satisfying super multi-view condition in integral imaging and evaluate the accommodation response when the observer is located inside and outside of the super multi-view region in integral imaging. To reveal the relation between the super multi-view condition and accommodation response of integral imaging, we perform the numerical analysis with super multi-view condition in integral imaging and present the experimental results of accommodation response using autorefractometer. [ABSTRACT FROM AUTHOR]

Background Failure of passive transfer ( FPT) in beef calves can be detected by refractometry. Nevertheless, different models of refractometers are available, and few studies compare them for the detection of FPT. Objectives To compare the accuracy of 4 different refractometers for measuring serum total protein concentrations in comparison with results obtained by the biuret method and, based on the serum IgG threshold of 1,600 mg/mL, to determine, for each refractometer, the optimal serum protein concentration's lowest threshold for successful passive transfer. Animals One hundred and eight healthy beef calves, 3-8 days of age. Methods Observational study. The concentrations of serum total proteins were determined with 4 different models of refractometers and compared with the biuret method by a Bland-Altman statistical method. The optimal serum protein concentration's lowest threshold for successful passive transfer was determined for each refractometer by receiver operating characteristic ( ROC) analysis. In addition, the serum immunoglobulin G ( IgG) concentration was compared with the serum gamma-glutamyl transferase (γ- GT) activity and with the total immunoglobulin concentration. Results The refractometric measurements were highly correlated with those obtained by the biuret method. Serum total protein concentration threshold values of 56, 58, 54, and 56 g/L were found respectively for the Atago, Atago ATC, Wolf ATC, and digital ATC refractometers. Immunoglobulins were highly correlated with IgG, whereas γ- GT only reflected colostrum uptake by the calf. Conclusions and clinical importance All refractometers could be used for the assessment of passive transfer using their individual serum protein concentration threshold. [ABSTRACT FROM AUTHOR]

Objective - To assess the relationship between total plasma protein (TPP) as measured by refractometry and serum hypoalbuminemia and hypoproteinemia in hospitalized dogs. Design - Retrospective, observational study conducted over 6-month period between March and August 2008. Setting - University teaching hospital. Animals - Four hundred and three hospitalized dogs in an ICU. Interventions - None. Measurements and Main Results - TPP, serum albumin, total protein, glucose, urea, cholesterol was measured from dogs enrolled in study. TPP was evaluated as a predictor for hypoalbuminemia defined both as albumin <25 g/L (<2.5 g/dL) and albumin <20 g/L (<2.0 g/dL), and serum hypoproteinemia, defined as serum total protein <40 g/L (<4.0 g/dL), using logistic regression. Impact of glucose, urea, cholesterol, and total bilirubin on refractometric readings were also assessed. TPP predicted hypoalbuminemia at albumin concentrations of <25 g/L (<2.5 g/dL) and <20 g/L (<2.0 g/dL) ( P<0.001). A TPP<60 g/L (<6.0 g/dL) predicted albumin <25 g/L (<2.5 g/dL) with 73% sensitivity and 86% specificity. A TPP<58 g/L (<5.8 g/dL) predicted a serum albumin <20 g/L (<2.0 g/dL) with 70% sensitivity and 80% specificity. For dogs with known risk factors where specificity optimization may be appropriate, refractometer TPP<50 g/L (<5.0 g/dL) and <48 g/L (<4.8 g/dL) predicted hypoalbuminemia at each level with >95% specificity, although sensitivity was poor. Refractometer TPP<58 g/L (<5.8 g/dL) predicted serum total protein of <40 g/L (<40 g/dL) with sensitivity of 82% and specificity of 84%. Hypercholesterolemia and hyperglycemia significantly affected TPP readings; an increase in serum glucose by 10 mmol/L (180 mg/dL) was associated with an average independent increase in refractometer TPP of 2.27 g/L (0.23 g/dL) ( P<0.001, 95% confidence interval=1.08-3.47) and an increase in serum cholesterol of 1 mmol/L (38.6 mg/dL) was associated with an average independent increase in refractometer TPP of 1.36 g/L (0.14 g/dL) ( P<0.001, 95% confidence interval=1.12-1.59). Conclusion - Suboptimal sensitivity limits the use of refractometric TPP for prediction of hypoalbuminemia in the context of patient screening; a high proportion of false negatives may result. However, identification of a refractometric TPP<58 g/L is strongly indicative of both serum hypoalbuminemia and hypoproteinemia, with high specificity, and warrants further investigation. Refractometric readings may be falsely increased in patients with hyperglycemia or hypercholesterolemia. [ABSTRACT FROM AUTHOR]

Summary [ABSTRACT FROM AUTHOR]

The article discusses a study which presented cure monitoring through a fiber-optic Fresnel refractometer as a viable proposition for carbon nanotube (CNT)-filled thermosets. It was noted that significant improvement in the signal-to-noise ratio is needed. The study argues, however, that this may not be necessary if the sources of the noise are intrinsic to the behavior of the resin system.

To estimate true Brix and alcoholic strength of must and wines without distillation, a novel approach using a refractometer and a hydrometer was developed. Initial Brix , apparent refractometer Brix , and apparent hydrometer Brix of must were measured by refractometer and hydrometer, respectively. Alcohol content was determined with a hydrometer after distillation and true Brix was measured in distilled wines using a refractometer. Strong proportional correlations among , and in sugar solutions containing varying alcohol concentrations were observed in preliminary experiments. Similar proportional relationships among the parameters were also observed in must, which is a far more complex system than the sugar solution. To estimate and of must during alcoholic fermentation, a total of 6 planar equations were empirically derived from the relationships among the experimental parameters. The empirical equations were then tested to estimate and in 17 wine products, and resulted in good estimations of both quality factors. This novel approach was rapid, easy, and practical for use in routine analyses or for monitoring quality of must during fermentation and final wine products in a winery and/or laboratory. [ABSTRACT FROM AUTHOR]

Background: Previous studies have demonstrated both poor and good correlation of total protein concentrations in various avian species using refractometry and biuret methodologies. Objectives: The purpose of the current study was to compare these 2 techniques of total protein determination using plasma samples from several psittacine species and to determine the effect of cholesterol and other solutes on refractometry results. Methods: Total protein concentration in heparinized plasma samples without visible lipemia was analyzed by refractometry and an automated biuret method on a dry reagent analyzer (Ortho 250). Cholesterol, glucose, and uric acid concentrations were measured using the same analyzer. Results were compared using Deming regression analysis, Bland–Altman bias plots, and Spearman's rank correlation. Results: Correlation coefficients ( r) for total protein results by refractometry and biuret methods were 0.49 in African grey parrots ( n=28), 0.77 in Amazon parrots (20), 0.57 in cockatiels (20), 0.73 in cockatoos (36), 0.86 in conures (20), and 0.93 in macaws (38) ( P≤.01). Cholesterol concentration, but not glucose or uric acid concentrations, was significantly correlated with total protein concentration obtained by refractometry in Amazon parrots, conures, and macaws ( n=25 each, P<.05), and trended towards significance in African grey parrots and cockatoos ( P=.06). Conclusions: Refractometry can be used to accurately measure total protein concentration in nonlipemic plasma samples from some psittacine species. Method and species-specific reference intervals should be used in the interpretation of total protein values. [ABSTRACT FROM AUTHOR]

Aim: Dynamic measurement of accommodation in subjects with myopia usually involves recording through soft contact lenses (CLs) to correct the refractive error. Conversely, dynamic accommodation measurement in emmetropic control subjects is generally undertaken without any corrective lenses. The aim of this experiment was to determine whether CL correction affects the measurement of accommodation microfluctuations using infrared refractometry, and whether this needs to be considered in studies which attempt to compare accommodation responses between the two groups. Methods: Ten young emmetropic subjects viewed a high contrast Maltese cross target monocularly using the right eye at a target vergence of 0 D. The subjects viewed the target under two conditions: with CL condition and without CL condition, where the subjects viewed the target with the eye only. Accommodation responses of the right eye were recorded continuously for 2 min at a sampling rate of 52 Hz using the Shin-Nippon SRW-5000 autorefractor. Results: No significant difference (two-tailed paired t-test, t9 = −1.499, p = 0.168) was found in mean accommodation response between the with CL (mean ± S.D. = −0.02 ± 0.24 D) and without CL conditions (mean ± S.D. = +0.01 ± 0.25 D). No significant (two-tailed paired t-test, t9 = 0.151, p = 0.883) difference in the magnitude of the accommodation microfluctuations was found between the with CL (mean ± S.D. = 0.162 ± 0.04 D) and without CL condition (mean ± S.D. = 0.169 ± 0.04 D). Power spectrum analysis revealed no differences in the characteristics of the microfluctuations waveform between the two conditions. A control experiment carried out on a subgroup of five subjects using a negative (−3 D) CL demonstrated that there was no significant effect of the dioptric power of the CL on the magnitude of the accommodation microfluctuations (anova: F3,15 = 0.254, p = 0.782). Conclusion: Thin soft CLs do not affect the magnitude or frequency characteristics of accommodation microfluctuations when measured using the Shin-Nippon SRW-5000. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of the present study was to measure equilibrium water content (EWC) and refractive index of conventional and silicone hydrogel soft contact lenses (SCL) using a hand refractometer and an automated refractometer. Methods: Sixteen SCL were used in this study including 12 conventional SCL not containing siloxane moieties (equilibrium water content (EWC) range: 38.6–74%) and the four silicone hydrogel based contact lenses currently available (WC range: 24–47%). Two experienced observers performed the measurements in a randomised order being masked by a third party during the three sessions at which the measurements were collected. The Atago N-2E hand refractometer and the CLR 12-70 digital refractometer were used. Data were analysed separately for conventional and silicone hydrogel materials. Results: Measured EWC and refractive index correlate better when measured with the instruments used in this study ( r2 = 0.979, p < 0.001) than the nominal parameters ( r2 = 0.666, p < 0.001). The linear relationship that correlates nominal and measured EWC shows higher spread of data when all lenses are analysed together ( r2 = 0.840) than when conventional hydrogel ( r2 = 0.953) and silicone hydrogel contact lenses ( r2 = 0.967) are analysed separately. Regarding refractive index, the relationship between nominal and measured values when all the lenses are considered together ( r2 = 0.794) becomes weaker when conventional hydrogel are considered separately ( r2 = 0.688), while a stronger relationship is observed for silicone hydrogel lenses ( r2 = 0.939). Hence, hand refractometry overestimates the EWC of silicone hydrogels, while automated refractive index measurements are more accurate in silicone hydrogels than in conventional hydrogels. Conclusions: New relationships are presented that correlate nominal and measured values of EWC and refractive index for the silicone containing hydrogels. The linear relationships derived fit well to the data. Hand refractometry overestimates the EWC of silicone hydrogel materials and this bias is related to the proportion of siloxane moieties in the material. Conversely, refractive index can be obtained more accurately with automated refractometry for silicone hydrogels than for conventional hydrogels. Present results are of interest in planning future clinical studies involving the measurement of EWC of current hydrogels. [ABSTRACT FROM AUTHOR]

Multi-refractor imaging is a technique for constructing a single two-dimensional image of a number of refractors by stacking multiple convolved and cross-correlated reversed shot records. The method is most effective with high-fold data that have been obtained with roll-along acquisition programs because the stacking process significantly improves the signal-to-noise ratios. The major advantage of the multi-refractor imaging method is that all the data can be stacked to maximize the signal-to-noise ratios before the measurement of any traveltimes. However, the signal-to-noise ratios can be further increased if only those traces that have arrivals from the same refractor are used, and if the correct reciprocal times or traces are employed. A field case study shows that multi-refractor imaging can produce a cross-section similar to the familiar reflection cross-section with substantially higher signal-to-noise ratios for the equivalent interfaces. [ABSTRACT FROM AUTHOR]

To conduct an experimental investigation of the effect of accommodative relaxation using far point shift stimuli for the reduction of asthenopia.Twenty-two female students accommodated to a far point shift stimuli during a 2-min period immediately after a 15-min sustained task on a three-dimensional display. Before and after the trial, their accommodative step response and symptoms were assessed. The far point shift stimuli in the optical system, which were presented on a refractometer, were created by moving the target scenery images from far to near, lineally centred about the far point position of each eye. During 2 min of fixating on the far point shift stimuli, changes in refraction were recorded in the same eye.While looking at the far point shift stimuli, 10 of 22 subjects had changes in refraction that showed a hypermetropic shift, and the other 12 subjects had changes in refraction that showed a myopic shift. The time taken for the accommodative step response from far to near post-trial in the myopic shift group was markedly prolonged, and the accommodative lag at the far target in the optometer was significantly increased. In the myopic shift group, the symptoms of‘eye fatigue’,‘eye pain’,‘eye heaviness’, and‘eye dryness’ also increased after the trial. In the hyperopic shift group, however, only the symptom of‘eye dryness’ increased, with no reduction of accommodation function.We suggest that accommodative relaxation by accommodative far point shift stimuli is effective in the reduction of asthenopia. [ABSTRACT FROM AUTHOR]

In a previous paper, the concept of a locally plane wave was explained theoretically. In such a configuration, the fringe pattern recorded on the film can be considered as a phase analyser. Here the experimental analysis is presented. showing examples of interesting applications to X-ray refractometry and to the visualization of the strain field around isolated defects. [ABSTRACT FROM AUTHOR]

An integrated system is described which we have found useful for efficiently collecting and analyzing both static and dynamic accommodation data using the Canon Autoref R-1 refractometer. The system consists of hardware modifications and software designed to both facilitate the measurement of accommodation and to process the resulting data. Several features of the Canon R-1, which may not be evident to some users, are also described. A program written in Microsoft C/C + + running under DOS, and designed for use on a PC, is available from the authors upon request. The College of Optometrists. Published by Elsevier Science Ltd. [ABSTRACT FROM AUTHOR]

This study investigated to what extent objective and subjective measurements of accommodation in darkness are affected by instrumentation or by flashed light stimuli that are arranged close to the subject's eye, and by the instructions given to the subjects. Subjects differed markedly in their susceptibility to these factors. Dark accommodation measured with an infra-red autorefractometer tended to be more distant by 0.2 D on the average if the autorefractometer allowed a free view into a large, but dark, room compared with a closed apparatus. When subjects were instructed to look into far or near distances during objective measurements, mean dark accommodation was more distant by 0.15 D and closer by 1.4 D, respectively, relative to the condition of 'relaxed eyes'. To find a simple screening test of dark accommodation, a 'number test' was investigated: subjects had to report which was the most sharply visible among a series of numbers that were simultaneously flashed at different optical distances in a Badal optometer. Objective measurements revealed that this test induced near shifts of 0.37 D on the average, relative to accommodation in a dark surround. Therefore, the results of the number test were only moderately correlated to objective measurements. [ABSTRACT FROM AUTHOR]

The integrity of the pre-lens tear film (PLTF) is an important determinant of the clinical performance of contact lenses. The PLTF of eight hydrogel lenses, ranging from 36.5% to 85% water content, was assessed on six asymptomatic lens wearers in a randomized, double-masked experiment. Using a specular reflection technique, the thicknesses of the lipid and aqueous phases were found to be greater on lenses of higher water content. Water content was measured before and after 90 min wear using a hand-held refractometer. Non-invasive tear break-up time was also found to be greater for higher water content lenses. No association was found between lens dehydration and PLTF characteristics. The differences in PLTF noted in this study may help to explain the differences noted between some lenses in their rates of surface deposition. [ABSTRACT FROM AUTHOR]

An attempt was made to derive a model for predicting the extent of hydrogel lens dehydration in vivo (ΔWv) by using a contact lens refractometer to (1 ) measure the water content (W) of eight lenses ranging from 36.5 to 85.8% water before and after 90 min lens wear by six subjects; and (2) measure the rate of dehydration of the same lenses in vitro (ΔWt), in a controlled, randomized, double-masked experiment. A significant correlation was demonstrated between W and the rate of change of ΔWt, (the dehydration rate, D), whereby lenses of higher water content dehydrate at a slower rate. No correlation was found between W and ΔWv or between D and ΔWv, thus precluding the development of a predictive model. Possible reasons for this failure, and directions for further research, are discussed. [ABSTRACT FROM AUTHOR]

An abstract of the article "Investigation of colostrum quality in beef cattle by radial immunodiffusion and brix refractometry," by S. Vandeputte, J. Detilleux, and F. Rollin is presented.

The article provides an overview of the study on the application of plasma samples for passive transfer assessment in calves through refractometry. It offers a comparison between measurements of serum total protein (sTP) and plasma total protein (pTP). It also highlights the agreement on measurement techniques for concentrations of immunoglobulin in the calves.

The article presents a study on the comparison of an optical analogue and digital hand-held refractometer for canine urine specific gravity measurement. The study made use of the freezing point depression osmometer to measure urine osmolality in 50 dogs. The result of the study shows that there was a clinically significant difference between the two refractometers.

Thanks to the peculiarities of optical fiber and its ability to be combined with nanotechnology, precise and accurate measurements of the changes in optical properties (i.e., refractive index) of the medium surrounding the fiber are becoming possible with a high degree of performance. Thus, optical fiber sensors (OFSs) are increasingly finding applications in biochemistry and biomedicine. Here, all types of optical fiber refractometers are covered, and they are classified into three main groups: interferometers, grating‐based structures, and resonance‐based structures (the resonance is induced by coating the optical fiber sensor with a thin film). The performance of these different structures is compared by means of the most common parameters: sensitivity, full width at half minimum or maximum, figure of merit, and quality factor. The aim here is to provide a reliable and easy‐to‐use tool to compare the performance of the most recent developments on fiber optic refractometers. [ABSTRACT FROM AUTHOR]

The article offers information on the DrySyn OCOT Mini Conversion Kit from Asynt Ltd., the LyoConstellation TM S10 freeze dryer from SP Scientific, and the AYE Combo refractometer/viscometer from Testa Analytical Solutions.

Purpose The aim of the study was to quantify low and high order Zernike aberrations in children and youths as well as to investigate influence of fogging and cycloplegia on the refraction and aberrations measurement. Methods KR‐1W Topcon aberrometer was used to measure aberrations in refractometer and aberrometer mode. Children were examined three times. First examination in whole group was performed after fogging stimulus used once ‐ in first of three continuous measurements, second after fogging stimulus performed for each measurement and third after pharmacological cycloplegia with 1% Tropicamid. Second and third measurements were performed in selected group of children. Totally 556 schoolchildren and 74 young sportsmen aged from 6‐to‐18 years were investigated. Average age was 13.87, SD 2.29 in large group and 11.33 years, SD 2.7 in smaller group. Results We found significant differences in spherical refraction measured after pharmacological cycloplegia compared to that after fogging. Refraction after cycloplegia was more hyperopic. There were higher differences in high hyperopic children. There were no differences between fogging and cycloplegic measurements in myopes higher then ‐2.00 D.. Aberrometry has given more myopic results then refractometry. Cylinder values were almost the same. Keratometer readings were the same in all measurements conditions. We found similar levels of high order aberrations in myopic, emmetropic and hyperopic children. There was no noticeable symmetry in high order aberrations between right and left eye. Conclusion Both methods of low order aberrations measurement are similar. Optical parameters of cornea do not depend on the cycloplegic status. Low order Zernike aberrations strictly correspond to the refraction error. [ABSTRACT FROM AUTHOR]