Search

Fiber optic sensors (FOSs) have transformed industrial applications with their high sensitivity and precision, especially in real-time monitoring. This study presents a fiber optic sensor based on multimodal interference (MMI) applied to detect honey adulteration. The sensor is built using a non-core multimode fiber (NC-MMF) segment spliced between two standard single-mode fibers (SMFs). We focus on reporting the detection of two main adulterants in honey that modify its refractive index (RI): the presence of glucose and moisture content. Detailed testing was performed with two commercially approved honey brands, named A and B. The sensor successfully detected glucose concentrations from 1% to 5% and moisture content from 0% to 20% for both brands. For glucose detection, we obtained sensitivity values −0.55457 nm/% for brand A and −2.61257 nm/% for brand B. In terms of moisture content in honey, we observed a sensitivity around −0.3154 nm/% and −0.3394 nm/% for brands A and B, respectively. Additionally, temperature tests were performed, showing that the sensor works optimally up to 30 °C. The results were validated using a conventional refractometer, showing a close agreement with the data obtained and confirming the reliability and accuracy of the proposed sensor. Compared to other refractometers, the MMI sensor offers advantages such as real-time monitoring, ease of assembly, cost-effectiveness, and minimal maintenance. Furthermore, the sensor represents an alternative tool to guarantee the quality and authenticity of honey, overcoming the limitations of conventional measurement techniques. [ABSTRACT FROM AUTHOR]

Objectives: The biuret method is frequently used to determine serum total protein. On the other hand refractometer, a quicker and less expensive option, is available to determine serum total protein. However, there is no study conducted in Ethiopia to compare serum total protein measurement in veterinary settings. Therefore, this study was conducted to compare the serum total protein concentration measurement in cattle and goats obtained by the biuret method and refractometer. Results: Serum samples from 60 cattle and 60 goats were assayed by both methods and data were analyzed with a paired t-test, Pearson's correlation, and Bland-Altman plots. There was a strong positive correlation between the total protein values determined with the refractometer and the biuret method in cattle (r = 0.93) and goats (r = 0.97). There were no significant differences (p > 0.05) in the protein values measured with the refractometer and those evaluated with the biuret method in both species. Bland-Altman plots showed that biases indicating the analytic and user error were 8.33% in both species which is below the acceptable total error (< 10%). Thus, refractometer can be used in place of biuret method since it is valid enough to measure serum total protein in cattle and goats. [ABSTRACT FROM AUTHOR]

Background: The immunocrit is a cost-effective and straightforward technique traditionally used to assess passive immunity transfer to newborn piglets. However, it has not been previously used for monitoring the effect of vaccination and/or infections. Therefore, this study aimed to evaluate the usefulness of the immunocrit technique as an immunological monitoring tool in a vaccination and challenge scenario, using porcine circovirus 2 (PCV-2) as pathogen model. The immunocrit ratio was monitored in PCV-2 vaccinated (V) and non-vaccinated (NV) 3-week-old piglets (study day 0, SD0) that were subsequently challenged with this virus at SD21 and followed up to SD42. Additional techniques (PCV-2 IgG ELISA, optical refractometry, and proteinogram) were performed to further characterize the results of the immunocrit analysis. Results: Immunocrit, γ-globulin concentration and PCV-2 S/P values followed similar dynamics: descending after PCV-2 vaccination but ascending after an experimental PCV-2 inoculation. However, statistically significant differences between V and NV animals were only found with the PCV-2 ELISA. In this case, V animals had significantly higher (p < 0.05) S/P values (S/P ratio = 0.74) than NV (S/P ratio = 0.39) pigs only after challenge at SD42. On the other hand, serum total protein obtained by refractometer (STPr) were maintained from SD0 to SD21 and increased in both groups from SD21 to SD42. Correlations between techniques were low to moderate, being the most robust ones found between immunocrit and optical refractometry (ρ = 0.41) and immunocrit with γ-globulins (ρ = 0.39). In a subset of sera, the proteinogram technique was applied to the whole serum and the supernatant of the immunocrit, with the objective to characterize indirectly the immunocrit fraction. The latter one included all protein types detectable through the proteinogram, with percentages varying between 64.3% (γ-globulins) and 82% (β-globulins). Conclusion: The immunocrit technique represented a fraction of the total serum proteins, with low to moderate correlation with all the complementary techniques measured in this study. Its determination at different time points did not allow monitoring the effect of vaccination and/or infection using PCV-2 as a pathogen model. [ABSTRACT FROM AUTHOR]

The refractive index of a liquid serves as a fundamental parameter reflecting its composition, thereby enabling the determination of component concentrations in various fields such as chemical research, the food industry, and environmental monitoring. Traditional methods for refractive index (RI) measurement rely on light deflection angles at interfaces between the liquid and a material with a known refractive index. In this paper, the authors present a new differential refractometer for the highly sensitive measurement of RI differences between two liquid samples. Using a configuration with two cells equipped with flat parallel plates as measuring elements, the instrument facilitates accurate analysis. Namely, the sensor signals from both the solution and the solvent cuvette are generated simultaneously with one laser pulse, reducing the possible fluctuations in the laser radiation intensity. Our evaluation shows the high sensitivity of RI measurements < 7 × 10 − 6 ), so this differential refractometer can be proposed not only as a high-sensitivity sensing tool that can be used for mobile detection of nanoparticles in solution samples but also to determine the level of environmental nano-pollution using water (including rain, snow) samples from various natural as well as industrial sources, thus helping to solve some important environmental problems. [ABSTRACT FROM AUTHOR]

In this study, we aimed to determine the quality of colostrum in sheep by using Brix refractometer. The research included 100 sheep of Merino X Kivircik crossbred. From each, we collected 15 mL of colostrum samples in falcon tubes within the first 8 h after delivery. Mean colostral IgG level of sheep was 156.68 ± 7.23 g L−1, optical and digital Brix refractometer values (%) were determined as 27.43 ± 0.53 and 27.69 ± 0.60, respectively. Ewes carrying twin lambs produced significantly higher quality colostrum than those carrying single lambs. However, parity did not affect the colostrum quality. Optical and digital Brix values were correlated with gold standard radial immunodiffusion (RID) colostral IgG level (r = 0.70 and r = 0.64, respectively). Also, optical and digital Brix refractometers were found to be highly correlated (r = 0.98, P < 0.001). While the optimal Brix value was 22% for the 50, 60 and 70 g L−1 IgG threshold values (by means of RID as the potential good quality threshold value for ewe colostrum quality), this value was 23% for 80 g L−1. We can conclude that Brix refractometers is a valuable tool for determining ewe colostrum quality. A cut point of 22% Brix for defining good quality colostrum in ewes was most appropriate for our data. [ABSTRACT FROM AUTHOR]

Bareke T, Addi A. 2024. Floral nectar secretion dynamics of Pavonia urens (Malvaceae) and honey production potential. Nusantara Bioscience 16: 89-95. The honey production potential of honey plant is estimated using the total floral nectar secretion potential of the plant foraged by honeybees within a given location. The current study aimed to determine the floral nectar secretion dynamics of Pavonia urens Cav. in addition to estimating the potential amount of honey that can be produced thereof. Nectar volume (using micropipette), nectar concentration (using digital refractometer), temperature, and humidity (using thermo hygrometer) were measured at 3 h intervals. Nectar volume and concentration differed significantly at different time points throughout the day. Also, nectar volume and concentration differed annually. There was a positive correlation between nectar volume and humidity as well as between temperature and nectar concentration. The mean nectar volume per 24 hours of P. urens was 7.23±0.43 µL. Individual flowers continuously secreted nectar for about 10 days throughout flower life. During each flowering season, an average of 823.5 mg g-1 of honey was generated per plant. Additionally, the average honey production capacity of P. urens was 35 kg ha-1. This suggests that P. urens has the capacity to produce honey; therefore, for sustainable honey production, planting and in-situ conservation of this plant are recommended. [ABSTRACT FROM AUTHOR]

The study was designed to ascertain the diagnostic efficacy of hand-held digital refractometer in determining total protein (TP). The Sipli sheep (n = 128) were grouped as per gender (females = 99, males = 29) and age (G1 = up till 1 year, n = 35; G2 = from 1 to 2 years, n = 63; G3 = above 2 years, n = 30). The results regarding the overall mean (±SE) values for the TPs attained through serum chemistry analyzer (TP1) and hand-held digital refractometer (TP2) were non-significantly (P≥0.05) different (59.2±1.6g/L and 59.8±0.5g/L, respectively). However, the reference intervals (RIs) were quite different for the two TPs being 45.1–95.7g/L and 57.0–67.0g/L for TP1 and TP2, respectively. Similar results were seen for gender-wise and group-wise results. On the contrary, the results regarding correlation coefficient and logilinear regression showed a negative correlation between the two TPs (r = -0.0244) with an adjusted r-square of 0.059 (5.9% probability). Furthermore, the three tests implied to assess the level of agreement between the two methods (Cronbach alpha, Intraclass correlation coefficient, and Bland & Altman test) revealed least agreement between the two methods. In a nutshell, the results of TP through digital refractometer were not in concordance with those attained through serum chemistry analyzer. However, it can cautiously be used if these results are compared with relevant corrected RIs. [ABSTRACT FROM AUTHOR]

The aim of the study was to determine the effects of breed and post-lambing time on sheep colostrum quality. In this study, colostrum samples taken at different times after lambing from 4 different sheep breeds (Tuj, Awassi, Morkaraman, Akkaraman) raised in Turkey were compared using Brix refractometer and color scoring. The sheep included in the study were placed in different paddocks according to their breeds. In the first week after lambing, a total of 7 colostrum samples were collected from each ewe, every 12 hours for the first 3 days and on the 7th day (mature milk sample). According to the data obtained from the study, it was determined that colostrum quality was affected by breed and milking duration (p<0.05). Brix values of colostrum in the first and second milking were found to be higher in the Akkaraman breed than in the Morkaraman breed (p<0.05). Additionally, it was determined that the color score decreased over time after lambing and this decrease was statistically significant (p<0.05). In conclusion, since the quality of sheep colostrum varies depending on breed and time, the quality of the colostrum to be fed for lamb health and performance must be determined in advance. [ABSTRACT FROM AUTHOR]

The aim of the study was to assess the quality of colostrum of Polish Holstein-Friesian cows on the first day after calving, by measuring the refractive index on the Brix scale with an electronic refractometer, as well as the colostrum yield. The influence of the following factors on these colostrum characteristics was analysed: time after calving, herd, lactation number, and length of the dry period before parturition. In total, colostrum from 21 cows (7 from each herd) was assessed. Yield was assessed, and antibody content on the Brix scale was determined using an electronic refractometer up to 2 hours after calving and at the time of subsequent milking on the farms (between 3 and 12 hours and between 13 and 24 hours after calving). Time after calving was shown to significantly affect the quality and yield of colostrum (P < 0.05). The immunological value of colostrum assessed on the Brix scale decreased at successive milking times after calving, amounting to 22.7%, 19.2% and 16.4%. However, the average colostrum yield increased with time (from an average of 6.5 kg in the first colostrum collection to 9.4 kg in the period between 13 and 24 hours after calving). The length of the dry period and the age of the cow were particularly important factors for the high value of the first colostrum. The best colostrum was produced by cows with a longer dry period, lasting from 46 to 59 days (23.4% Brix) and by older cows in lactations from 4 to 7 (24.2% Brix). The correlation and regression coefficients calculated in the study indicate that the increase in the yield of colostrum obtained up to 2 hours after calving is associated with a decrease in its quality. Extension of the dry period before parturition is accompanied by an increase in antibody content assessed on the Brix scale. Despite the fact that routine assessment of colostrum quality using an electronic refractometer is known to have tangible benefits, it is still not widely conducted. [ABSTRACT FROM AUTHOR]

An updated version of an Invar-based dual Fabry–Perot cavity refractometer utilizing the gas modulation methodology has been characterized with regard to its ability to assess gas pressure in the low pressure regime, defined as the regime in which the instrumentation is mainly limited by the constant term a in the [ (a) 2 + (b × P) 2 ] 1 / 2 expression for the uncertainty. It is first concluded that this ability is predominantly limited by three entities, viz., the empty cavity repeatability, the residual gas pressures in the evacuated (measurement) cavity, and the contamination of the gas residing in the measurement cavity that originates from leaks and outgassing. We then present and utilize methods to separately estimate the uncertainty of the updated refractometer from these entities. It was found that, when utilizing gas modulation cycles of 100 s and when addressing nitrogen, the system can assess pressure in the low pressure regime with an expanded uncertainty (k = 2) of 0.75 mPa, mainly limited by the empty cavity repeatability and outgassing of hydrogen. This is more than 1 order of magnitude below the previously assessed low pressure performance of the instrumentation. [ABSTRACT FROM AUTHOR]

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]

This study investigated the interrelationships between the parameters of density, optical refraction, the volume fraction of ethanol and the total extract, using model solutions and samples of wine materials. The regularities of changes in refractometer readings in the process of alcoholic fermentation have been studied. The functional dependence of the value of the volume fraction of ethanol in the finished wine products on the density and scale of refractometer values has been established. A technique is proposed for controlling the process of alcoholic fermentation of grape must, based on the use of refractometry. Finally, we present an algorithm to calculate the composition (volume fraction of ethanol, mass concentration of the total extract) of the fermentation product from its physical properties (density, refractive index), the coefficient of determination was R2 = 0.975. [ABSTRACT FROM AUTHOR]

Simple Summary: Newborn goat kids need to consume high-quality colostrum in the first hours after birth to ensure adequate transfer of passive immunity, through the absorption of immunoglobulins. However, some goats fail to produce high-quality colostrum, and tools for on-farm assessment of colostrum quality are needed. This work evaluated the quality of colostrum in Malagueña dairy goats, through measurement of immunoglobulin G (IgG), fat and protein concentrations in colostrum during the first 3 days after parturition. A handheld optical Brix refractometer, an instrument that is easy to use on the farm, was evaluated for accuracy to estimate colostrum quality. The optical Brix refractometer was found to be suitable for on-farm use to estimate the IgG content in the goat colostrum. Failure of passive immunity transfer is one of the main causes of increased susceptibility to infectious agents in newborn kids. To ensure successful transfer of passive immunity, kids need to be fed high-quality colostrum, containing an adequate concentration of IgG. This work evaluated the quality of colostrum obtained in the first 3 days postpartum from Malagueña dairy goats. The IgG concentration in colostrum was measured using an ELISA as a reference method, and it was estimated by optical refractometer. Colostrum composition in terms of fat and protein was also determined. The mean concentration of IgG was 36.6 ± 2.3 mg/mL, 22.4 ± 1.5 mg/mL and 8.4 ± 1.0 mg/mL on days 1, 2 and 3 after parturition, respectively. Brix values obtained using the optical refractometer were 23.2%, 18.6% and 14.1% for days 1, 2 and 3, respectively. In this population, 89% of goats produced high-quality colostrum with IgG concentrations of >20 mg/mL on the day of parturition, but this percentage declined dramatically over the following 2 days. The quality of the fresh colostrum estimated with the optical refractometer was positively correlated with those obtained using ELISA (r = 0.607, p = 0.001). This study highlights the importance of feeding first-day colostrum to newborn kids and demonstrates that the optical Brix refractometer is suitable for the on-farm estimation of IgG content in colostrum. [ABSTRACT FROM AUTHOR]

The measurement of the refractive index typically requires the use of optical ellipsometry which, although potentially very accurate, is extremely sensitive to the structural properties of the sample and its theoretical modeling, and typically requires specialized expertise to obtain reliable output data. Here, we propose a simple diffractive method for the measurement of the refractive index of homogenous solid thin films, which requires only the structuring of the surface of the material to be measured with the profile of a diffraction grating. The refractive index of an exemplary soft-moldable material is successfully estimated over a wide wavelength range by simply incorporating the measured topography and diffraction efficiency of the grating into a convenient scalar theory-based diffraction model. Without the need for specialized expertise and equipment, the method can serve as a simple and widely accessible optical characterization of materials useful in material science and photonics applications. [ABSTRACT FROM AUTHOR]

Copyright of Diversitas Journal is the property of Diversitas Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Erosion of crops genetic resources is happening due to replacement of traditional landraces with high genetic diversity by modern commercial varieties with high genetic uniformity. Due to good resistance to climatic conditions and on the basis of previous pomological and sensory analyses, it is assumed that the tomato landraces have good quality of fruit and better taste compared to modern commercial varieties. Tomato landraces are characterized by high content of vitamins and minerals and other antioxidants. The aim of this research was to determine differences in biochemical characteristics between different tomato landraces from Gene Bank of Republic of Srpska. The 2-year research (2018 and 2019) was conducted on 10 tomato landraces from the Gene Bank of Republic of Srpska: GB00874, GB01107, GB01110, GB01123, GB01126, GB01128, GB01129, GB01132, GB01238 and GB01239. Analyzed biochemical characteristics were: total soluble solids content (by the digital refractometer), lycopene (spectrophotometrically), total phenolic (Folin-Ciocalteu - FC colorimetric method) and total flavonoids (colorimetric method with aluminum chloride). Total soluble solids ranged from 4.4 °Brix (GB01238) to 7.8 °Brix (GB01129) in 2018 and from 5.2°Brix (GB01123) to 7.8 °Brix (GB01110) in 2019. Lycopene content in yellow fruit color landraces ranged from 0.26 mg/kg (GB01238) to 1.06 mg/kg (GB01132) in 2018 and from 0.51 mg/kg (GB01238) to 0.74 mg/kg (GB01132) in 2019. Lycopene content in red fruit color landraces ranged from 24.9 mg/kg (GB01239) to 148.3 mg/kg (GB01110) in 2018 and from 28.3 mg/kg (GB01123) to 174.7 mg/kg (GB00874) in 2019. Considering the content of phenols, the highest amount was measured in the landrace GB01128 which had and the highest flavonoid content. This is the first insight in nutritional biochemistry of tomato landraces from Gene Bank of Republic of Srpska. Tomato landraces show high diversity in all analyzed biochemical characteristics, which suggest they possess high genetic diversity, good fruit quality and good base for further nutrition research on this landraces. [ABSTRACT FROM AUTHOR]

In this work, a fiber laser refractometer based on a fiber ball lens (FBL) interferometer is proposed. The linear cavity erbium-doped fiber laser uses an FBL structure acting as a spectral filter and sensing element for determining the RI of a liquid medium surrounding the fiber. The optical interrogation of the sensor is the wavelength displacement of the generated laser line as a function of the RI variations. For the proposed FBL interferometric filter, the free spectral range of its wavelength-modulated reflection spectrum is adjusted to maximum in order to obtain RI measurements in a range of 1.3939 to 1.4237 RIU, from laser wavelength displacements in a range from 1532.72 to 1565.76 nm. The obtained results show that the wavelength of the generated laser line is a linear function of the RI variations on the medium surrounding the FBL with a sensitivity of 1130.28 nm/RIU. The reliability of the proposed fiber laser RI sensor is analytically and experimentally investigated. [ABSTRACT FROM AUTHOR]

Colostrum quality is generally defined by the IgG concentration in colostrum, and many methods have been used to assess it. Methods to measure colostrum quality both in the laboratory and in the field have been validated in cattle; however, this is only a recent topic of interest for sheep colostrum. Laboratory-based methods are often time consuming and require trained personnel compared with new handheld evaluation tools such as the digital Brix refractometer, which gives real-time results. The aims of this study were to (1) evaluate the relationship between the digital Brix refractometer and constituents indicative of quality (IgG, protein, fat, and lactose) in colostrum and transition milk, and (2) determine an appropriate Brix % cut-off value for the Brix refractometer in sheep colostrum and transition milk. The study used 50 colostrum samples (collected at 0 h postpartum, before lambs' sucking) and 169 transitional milk samples (collected at 4 and 24 h postpartum, after lambs had sucked) collected over 6 lambing trials in 2 years (2019 and 2020). We concluded that the Brix refractometer results correlated weakly with IgG concentration determined by radial immunodiffusion assay in colostrum collected at 0 h postpartum (r = 0.11) and in transition milk collected at 4 h postpartum (r = 0.12); however, a moderate to strong correlation was shown in transition milk samples collected at 24 h (r = 0.66). Brix % was significantly correlated with fat %, lactose %, and protein % at all timepoints. To determine an appropriate Brix % cut-off value indicating an IgG concentration of 20 mg/mL, we analyzed sensitivity and specificity of the Brix refractometer at 0, 4, and 24 h. In samples collected at 0 and 4 h, the highest combination of sensitivity, specificity, and accuracy was achieved at a Brix % cut-off value of 29%; in samples collected at 24 h postpartum, a Brix % cut-off value of 27% gave the highest sensitivity, specificity, and accuracy. Overall, the Brix refractometer has potential as a useful in-field tool for researchers and producers in both extensively and intensively managed flocks to measure and determine the quality of sheep colostrum and transition milk. [ABSTRACT FROM AUTHOR]

Simple Summary: The adequate passive transfer of immunity, which is estimated indirectly and rapidly through measuring serum total proteins, is vital for newborn calves. At the same time, cows' serum total proteins concentration is considered an indicative parameter of their health and metabolic status. In the present study, the genetic parameters of Holstein dairy cow and calf total proteins concentration measured by a digital Brix refractometer were studied. Heritability estimates of the traits suggest that genetic selection would be feasible and useful. In addition, results offer interesting perspectives regarding calf and cow health and, therefore, herd sustainability. The high positive genetic correlation between calf serum total proteins and colostrum total solids, is a very important finding and allows us to perform genetic selection for both traits simultaneously by collecting a single phenotype. The objective was to estimate the genetic parameters of serum total protein concentration in newborn calves (calfSTP) and post parturient dairy cows (cowSTP). The study included 1013 calves and 989 cows from 10 dairy farms. Calf blood samples were collected 24–48 h after parturition while cow blood and colostrum samples were collected in the first 24 h after calving. Blood serum total protein and colostrum total solids content were determined using a Brix refractometer. Chemical analysis of colostrum was performed with Milkoscan. Univariate mixed linear models were used to estimate the heritability of calfSTP and cowSTP and their genetic and phenotypic correlations with colostrum traits. The heritability estimates of calfSTP and cowSTP were 0.21 and 0.20 (p < 0.05), respectively. Strong genetic correlations (r > 0.90) were detected between calfSTP and colostrum total solids and protein content (p < 0.05). Corresponding phenotypic correlations were 0.31–0.33 (p < 0.05). No genetic or phenotypic correlations were detected with colostrum fat content while the respective correlations with lactose were negative (−0.82 and −0.19, p < 0.05). No genetic correlations were detected between cowSTP and colostrum traits and only a low negative phenotypic one with lactose was detected. The results confirm that genetic selection aiming to improve the passive transfer of immunity in newborn calves and general fresh cow health would be feasible. [ABSTRACT FROM AUTHOR]

Summary: This study compared two measurement methods to assess serum total protein (TP) concentration (refractometer and biuret reaction) in Warmblood foals on a farm with occurrence of equine proliferative enteropathy (EPE). The aim was to investigate the reliability of TP measurement by an automatic temperature compensated handheld refractometer in foals and its use as a diagnostic monitoring tool, for example in the context of a Lawsonia monitoring programme. In addition, the correlation between TP and albumin was investigated as well as the influence of the outdoor temperature on the measurement methods. Serum TP values by refractometry and by biuret reaction (n=772) were compared in healthy and sick foals (n=744), aged one to eight months. Additionally, the correlation between TP and albumin concentrations was analysed. The study results were assigned to one of two groups, group A or B. The samples from group A (outdoor temperatures ≤29°C) were taken over several weeks, whereas the samples of group B (outdoor temperature 33°C) were all collected on one hot day. In both groups, the measurements were compared based on one single sample per foal. In group A (outdoor temperatures ≤29°C), serum TP median value by refractometer was 61g/L (25% and 75% percentile: 58–64g/L) and 59.8g/L (25% and 75% percentile: 57–62.6g/L) by biuret reaction. The TP values of both measurement methods, refractometry and biuret reaction, correlated positively with each other (r=0.79). There was no significant difference (p=0.98) between the two methods. Albumin values correlated positively with TP values in this group (refractometer: r=0.19 and biuret reaction: r=0.27). In group B (outdoor temperature 33°C), serum TP median value by refractometry was 52g/L (25% and 75% percentile: 50–55g/L) and 59.9g/L (25% and 75% percentile: 57.2–62g/L) by biuret. The TP values of both methods correlated positively with each other (r=0.87). In this group, TP values measured by refractometry were significantly lower than by biuret reaction (p<.0001). Albumin values correlated positively with TP values (refractometer: r=0.14 and biuret reaction: r=0.18). Comparing TP values with a pooled reference range for foals aged one to nine months (50–73g/L), in group A (outdoor temperatures ≤29°C), 98.4% (1370/1392) of the values from both measurement methods were within the reference range, while 1.6% (22/1392) were outside. 0.9% (12/1392) of the values were in the range commonly observed in foals with Lawsonia intracellularis infection (<50g/L). In group B (outdoor temperature 33°C), 87.5% (133/152) of the values were within the reference range and 12.5% (19/152) were outside. 12.5% (19/152) of the values were in the range seen in foals with Lawsonia intracellularis infection (<50g/L). Group B (outdoor temperature of 33°C) differed from group A (outdoor temperatures ≤29°C) by noticeable deviating refractometrically measured TP values from chemically measured TP values. In general, the results of this study showed no significant difference between the two measurement methods. However, significant deviations occurred at outdoor temperature of 33°C. Therefore, when using the refractometer, it seems to be important that samples are taken at moderate outside temperatures (≤29°C) or analysed promptly or stored refrigerated. Since only a small number of TP values was <50g/L, a statement of the comparability of the two applied measuring methods in the measuring range of interest for Lawsonia intracellularis is limited. [ABSTRACT FROM AUTHOR]

Honey is a naturally occurring material made by bees from the sweet, fragrant nectar of flowers. More than 200 substances have been identified in honey, the majority of which are sugars and water. Certain physical characteristics of honey, such as crystallization and viscosity, are substantially affected by moisture. The honey may be stored for a longer period of time because of the low water content, which shields it from microbial activity. Honey from around Pozarevac, the place in Serbia with the largest production of honey, was controlled. A refractometer from A. KRÜSS Optronic GmbH was used for this research. In the period from 2019 to 2021, 99 samples of acacia honey and 114 samples of meadow honey were analyzed. The average values of water percentage in the indicated period in both types of honey were between 16 % and 17 %. Based on this research, it can be concluded that the percentage of water in acacia and meadow honey was below the maximum allowed values according to national and European regulations. Below 17 % water content, honey fermentation is inhibited. Honey with a water percentage above 17 % is sensitive to fermentation, while honey with a water content above 19 % is extremely vulnerable. [ABSTRACT FROM AUTHOR]

Using the technology of metalorganic chemical vapor deposition (MOCVD), fully fiber refractometers based on the lossy mode resonance (LMR) were obtained and investigated. The sensors are made on the basis of a section of optical fiber etched to the core with films of titanium dioxide (TiO2) and tin (TiO2/SnO2) deposited on the side surface. The sensitivity of the obtained sensors to the refractive index of the surrounding liquid medium is compared depending on the composition and thickness of the film coating. The sensitivity of the fiber sensor with a two-layer coating in the wavelength range of 1.33–1.35 microns was 4850 nm/RIU. Before measurements, cells suspended in liquid were concentrated on the surface of the sensor due to the effect of optical tweezer. Particles were attracted from the suspension when launching into the fiber radiation from a diode laser with a power of 10 mW. With the help of fabricated fiber sensors, the change in the refractive index of a suspension containing living cells of the microalgae Chlorella Vulgaris was monitored. The possibility of assessing the influence of external conditions on the life process of algae with real-time control using fabricated fiber sensors is shown. [ABSTRACT FROM AUTHOR]

In this work, a set of titanium nitrides thin-films was synthesized with the technique of reactive RF and DC magnetron-sputtering. To demonstrate the versatility and effectiveness of the deposition technique, thin films were deposited onto different fiber structures varying the deposition parameters for optical applications as saturable absorbers in passively q-switched fiber lasers and as lossy mode resonance fiber refractometers. After deposition, optical and electronical properties of samples were characterized by UV–Vis and XPS spectroscopies, respectively. Samples presented coexisting phases of Ti nitride and oxide, where the nitride phase was non-stoichiometric metallic-rich, with a band gap in the range of Eg = 3.4–3.7 eV. For all samples, glass substrates were used as templates, and on top of them, optical fibers were mounted to be covered with their respective titanium compounds. [ABSTRACT FROM AUTHOR]

Background: Refraction is one of the key components of a comprehensive eye examination. Auto refractometers that are reliable and affordable can be beneficial, especially in a low-resource community setting. The study aimed to validate the accuracy of a novel wave-front aberrometry-based auto refractometer, Instaref R20 against the open-field system and subjective refraction in an adult population. Methods: All the participants underwent a comprehensive eye examination including objective refraction, subjective acceptance, anterior and posterior segment evaluation. Refraction was performed without cycloplegia using WAM5500 open-field auto refractometer (OFAR) and Instaref R20, the study device. Agreement between both methods was evaluated using Bland-Altman analysis. The repeatability of the device based on three measurements in a subgroup of 40 adults was assessed. Results: The refractive error was measured in 132 participants (mean age,30.53 ± 9.36 years, 58.3% female). The paired mean difference of the refraction values of the study device against OFAR was − 0.13D for M, − 0.0002D (J0) and − 0.13D (J45) and against subjective refraction (SR) was − 0.09D (M), 0.06 (J0) and 0.03D (J45). The device agreed within +/− 0.50D of OFAR in 78% of eyes for M, 79% for J0 and 78% for J45. The device agreed within +/− 0.5D of SR values for M (84%), J0 (86%) and J45 (89%). Conclusion: This study found a good agreement between the measurements obtained with the portable autorefractor against open-field refractometer and SR values. It has a potential application in population-based community vision screening programs for refractive error correction without the need for highly trained personnel. [ABSTRACT FROM AUTHOR]

Purpose: InstaRef R20 is a handheld, affordable auto refractometer based on Shack Hartmann aberrometry technology. The study's objective was to compare InstaRef R20's performance for identifying refractive error in a paediatric population to that of standard subjective and objective refraction under both pre- and post-cycloplegic conditions. Methods: Refraction was performed using 1) standard clinical procedure consisting of retinoscopy followed by subjective refraction (SR) under pre- and post-cycloplegic conditions and 2) InstaRef R20. Agreement between both methods was evaluated using Bland-Altman analysis. The repeatability of the device based on three measurements in a subgroup of 20 children was assessed. Results: The refractive error was measured in 132 children (mean age 12.31 ± 3 years). The spherical equivalent (M) and cylindrical components (J0 and J45) of the device had clinically acceptable differences (within ± 0.50D) and acceptable agreement compared to standard pre- and post-cycloplegic manual retinoscopy and subjective refraction (SR). The device agreed within ± 0.50D of retinoscopy in 67% of eyes for M, 78% for J0 and 80% for J45 and within ± 0.50D of SR in 70% for M and 77% for cylindrical components. Conclusion: InstaRef R20 has an acceptable agreement compared to standard retinoscopy in paediatric population. The measurements from this device can be used as a starting point for subjective acceptance. The device being simple to use, portable, reliable and affordable has the potential for large-scale community-based refractive error detection. [ABSTRACT FROM AUTHOR]

Sweetness or sugar content, represented by soluble solids contents (SSC), is a vital quality trait in watermelon breeding which can be assessed by the refractive index method. However, sampling watermelon juice out of the pulp is a process that is both labor-intensive and error-prone. In this study, we developed an automatic SSC measurement system for watermelon breeding to improve efficiency and decrease costs. First, we built an automatic cutting system to cut watermelons into precise halves, in which a laser rangefinder is used to measure the distance from the upper surface of the watermelon to itself, and thus, the diameter is estimated. The experiments showed a high correlation between the estimated diameters and the ground truths, with R 2   =   0.9608 and RMSE   =   4.321 . Then, we built an automatic Brix measurement system to obtain the Brix data from a central point on the watermelon's section, where an image analysis procedure is applied to locate the testing point. This is then transformed to the camera coordination system, and a refractometer is driven by a 3-axis robotic arm to reach the testing point. Brix measurement experiments were conducted using three vertical gaps and four lateral gaps between the probe of the refractometer and the pulp. The result showed that the best parameters were a vertical gap of 4 mm and a lateral gap of 2 mm. The average accuracy reached 98.74%, which indicates that this study has the potential to support watermelon breeding research. [ABSTRACT FROM AUTHOR]

• A novel optical fiber sensor utilizing a single smart functional layer was developed. • Ag/Yb 2 O 3 nanostructure coated with a green chemistry method was deposited. • The sensor employs the lossy mode resonance (LMR) technique. • Ag/Yb 2 O 3 nanostructure based on molecularly imprinted polymer (MIP) has a LOD of 0.0987 μM. • The LMR-based fiber optic sensor demonstrates a sensitivity of 5.3611 nm/μM. This study presents a novel optical fiber refractometer based on a single smart functional layer of Ag/Yb 2 O 3 nanostructure, synthesized by a green chemistry method using oak fruit extract. The optical phenomena of surface plasmon resonance (SPR) and lossy mode resonance (LMR) were investigated based on the performance of the real and imaginary parts of the dielectric constant function of nanoparticles and nanostructures coated on the optical fiber. The Ag/Yb 2 O 3 nanostructure enhances the LMR phenomenon and acts as an electron mediator for the detection of tamoxifen (TAM) drug, a widely used anticancer agent. The Ag/Yb 2 O 3 nanostructure was coated on a curved optical fiber surface along with a molecularly imprinted polymer (MIP) layer, which provided selective recognition of TAM molecules. The sensor probe showed rapid and reversible adsorption/desorption of TAM, with a high sensitivity of 5.3611 nm/µM and a limit of detection (LOD) and limit of quantification (LOQ) of 0.0987 μM and 0.32902 μM, respectively. The sensor also exhibited good recovery rate and effectiveness in real samples, demonstrating its potential for sensivity applications. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, we propose a demodulation method for refractive index (RI) sensing with tilted fiber Bragg gratings (TFBGs). It operates by monitoring the TFBG cladding mode resonance “cut-off wavelengths.” The idea of a “cut-off wavelength” and its determination method are introduced. The RI sensitivities of TFBGs are significantly enhanced in certain RI ranges by using our demodulation method. The temperature-induced cross sensitivity is eliminated. We also demonstrate a parallel-double-angle TFBG (PDTFBG), in which two individual TFBGs are inscribed in the fiber core in parallel using a femtosecond laser and a phase mask. The RI sensing range of the PDTFBG is significantly broader than that of a conventional single-angle TFBG. In addition, its RI sensitivity can reach 1023.1 nm/refractive index unit in the 1.4401–1.4570 RI range when our proposed demodulation method is used. [ABSTRACT FROM AUTHOR]

In this paper, a comparative analysis between the hand-held refractometer and other methods (TKN and CHNS) was accomplished for the estimation of nitrogen percentage (N%) in urea, nano urea fertilizer, and diesel exhaust fluid (DEF) solution. In order to compare the performance of all methods/devices, the detection of N% in different concentrations of urea, nano urea, and DEF were evaluated in terms of their linearity. The most important finding of this study was that the refractometer-based device revealed a good linear coefficient up to 40% urea solution (R2 = 0.99918) among other approaches, which means the estimation of N% is more close to the theoretical value. Moreover, the refractometer has detected the urea, nano urea, and DEF samples within 3 s which were quite fast as compared to other tested methods and no requirement of any chemicals during the sample preparation and analyses. Thus, the finding of this study suggests that a hand-held urea refractometer-based portable device can be used for onsite N% determination by the fertilizer and DEF manufacturing industries and their customers due to its low cost, low power requirement, reliable estimation, rapid N% detection, and its environmental suitability. [ABSTRACT FROM AUTHOR]

A fiber-optic refractometer for various liquids with refractive indices in the range from 1.33 to 1.43 has been manufactured and tested. The sensor is based on a thin silicon oxynitride (Si3N4-xOx) film coated thinned optic fiber section (taper) obtained in a multimode all-silica optical fiber by chemical etching of the reflective cladding. The film was deposited on the cylindrical surface of the thinned fiber by the surface plasma chemical vapor deposition method (SPCVD). Lossy mode resonance (LMR) was observed in the transmission spectrum of the coated taper at a wavelength dependent on the refractive index of the liquid in which the taper was immersed. We tested the obtained sensors in distilled water, isopropyl alcohol, dimethylformamide, and their aqueous solutions. It was found that with the help of the SPCVD, one can obtain a set of sensors in a single deposition run with the dispersion of sensitivity and spectral position of LMR no more than 5%. Maximum sensitivity of the manufactured sensors to surrounding media refractive index (SMRI) variation exceeds 1090 nm/RIU, which is the highest value recorded to date for a sensor with a non-oxide coating. [ABSTRACT FROM AUTHOR]

This paper describes a compact refractometer in visible with optical bounds states in the continuum (BICs) using silicon nitride (Si3N4) based sub-wavelength medium contrast gratings (MCGs). The proposed device is highly sensitive to different polarization states of light and allows a wide dynamic range from 1.330 (aqueous environment) to 1.420 (biomolecules) monitoring, apart from its being thermally stable. The proposed sensor has a sensitivity of 363 nm/RIU for X polarized light and 137 nm/RIU for Y polarized light. The spectral characteristics have been obtained with a high angular resolution for the smaller angle of incidence, which confirms the BIC hybrid modes with good quality factors and enhanced field confinement. The device is based on a normal-to-the-surface optical launching strategy to achieve exceptional interrogation stability and alignment-free performance. This system can also be used in the CMOS photodetectors for on-chip label-free biosensing. [ABSTRACT FROM AUTHOR]

In this work, a fiber optic-based refractometer has continuously been developed for measuring carbon dioxide (CO 2) using the evanescent wave method. Consequently, this technique is utilized to determine the light absorption values. Further, the chemical compound is also used to coat onto the modified sensing probe. However, this probe is, generally, made from multi-mode fiber (MMF). Moreover, the principle of altering the refractive index (RI) value is applied by removing the cladding of the sensing probe using hydrofluoric acid (HF). In addition, the zinc oxide (ZnO) mixed with the sodium silicate (Na 2 SiO 3), known for its CO 2 absorption capabilities, is used as a compound to coat the modified cladding. Besides, the sensing probe has been developed in three selected lengths (L) which are 10, 20, and 25 mm, and then tested from 0 to 40 % of CO 2 concentration. Moreover, a biogas analyzer has been operated as a standard reference instrument. Afterward, an engineering application software is also developed for data processing to analyze the data in the relationship between the differential voltage, percentage of attenuation, and percentage of concentration versus time domain, respectively. The experimental results reported that the developed sensing can detect CO 2 in any sensing length from 8.11 to 38.25 % with a sensitivity of 0.0102 mV/%concentration. In addition, a percentage attenuation of 2.11 %, 14.52 %, and 29.29 % is achieved in whole sensing lengths. However, this analyzes that at 10 mm the probe is more suitable due to its high responsibility to detect the CO 2. Furthermore, the experimental results showed that the selected compound can recover with a recovery time of approximately 6 min. [ABSTRACT FROM AUTHOR]

In this study, 737 individual sheep milk samples were collected 2 times from morning milkings to evaluate the relationships between Brix refractometer measurements and milk constituents— protein and fat percentages—to verify its ability to predict milk constituents. The Pearson's simple (rSP) and partial (rPP) correlations between milk constituents were calculated, and several first- and second-order regressions were tested to predict the protein and fat percentages. The rSP coefficients between the Brix refractometer measurement and fat (rSP = 0.46) and protein (rSP = 0.87) contents were different from the rPP coefficients, particularly for fat percentage (rPP = 0.04 and rPP = 0.82, for fat and protein percentages, respectively). The results of the forecasts can be considered satisfactory only for the first order regression that predicted the percentage of milk protein, while the regression that predicted the percentage of fat + milk protein presented a weak forecasting capacity. [ABSTRACT FROM AUTHOR]

In this work, a fiber laser refractometer based on a fiber ball lens (FBL) interferometer is proposed. The linear cavity erbium-doped fiber laser uses an FBL structure acting as a spectral filter and sensing element for determining the RI of a liquid medium surrounding the fiber. The optical interrogation of the sensor is the wavelength displacement of the generated laser line as a function of the RI variations. For the proposed FBL interferometric filter, the free spectral range of its wavelength-modulated reflection spectrum is adjusted to maximum in order to obtain RI measurements in a range of 1.3939 to 1.4237 RIU, from laser wavelength displacements in a range from 1532.72 to 1565.76 nm. The obtained results show that the wavelength of the generated laser line is a linear function of the RI variations on the medium surrounding the FBL with a sensitivity of 1130.28 nm/RIU. The reliability of the proposed fiber laser RI sensor is analytically and experimentally investigated.

Evaluation of coconut (Cocos nucifera L.) varieties for growth and tender nut quality was carried out at Horticulture Research and Extension Centre (UHS, Bagalkot), Arsikere, Karnataka. The highest palm height (2.35 m) was recorded in Kalpa Dhenu, whereas it was lowest (1.22 m) in COD at the age of nine years. Palm girth (101.78) and leaf length (4.73 m) were maximum in variety Kalpatharu. Higher amount of tender nut water (605 ml/nut) in Kalpa Dhenu, whereas, Gautami ganga (551.7 ml/nut) and COD (520 ml/nut) had optimum quantiy of water. Gauthami Ganga recorded highest TSS (6.1°Brix) and lowest titrable acidity (0.05%). COD recorded maximum total sugars (6.79 g/100 ml) and lowest acidity (0.05%). Gauthami Ganga had optimum quantity of mineral content (61.47 mg/100 ml calcium, 10.87 mg/100 ml magnesium, 2023.33 ppm potassium and 23.33 ppm sodium). Organoleptic evaluation indicated that Gauthami Ganga (8.5) and COD (7.23) were the best for tender nut purpose as both of them ranked good for taste of water. [ABSTRACT FROM AUTHOR]

Context: The high incidence of lamb mortality in Merino sheep is a persistent issue for the industry. Poor-quality colostrum or inadequate colostrum consumption increases the risk of low energy intake and failed passive immunity transfer, resulting in lamb mortality. The rapid assessment of colostrum quality and intake would be a valuable tool for producers which house ewes for lambing. Aims: This experiment determined the relationship and accuracy of analysis techniques to measure immunoglobulin G (IgG) and total protein (TP) concentrations within ewe colostrum and lamb serum and compared those results against digital hand-held refractometers. Methods: Merino ewe colostrum and lamb blood were sampled at 4 and 24 h post-partum during autumn (n = 93 ewes) and spring (n = 79 ewes) in 2018. Colostrum was analysed for total milk solids (%) and lamb serum was analysed for total blood serum protein (%), and both colostrum and lamb serum were analysed for IgG and TP using in-house laboratory analysis techniques. Correlation coefficients were performed to identify the relationship between the different assessment methods. Key results: There was a significant Pearson's correlation (P < 0.05) between 4 h total milk solids and TP (R = 0.19), between total milk solids and IgG (R = 0.19), and TP and IgG (R = 0.38). For 24 h colostrum samples, the significant correlations (P < 0.001) between TP and IgG (R = 0.54) and total milk solids and IgG (R = 0.56) were higher than the correlation between total milk solids and TP (R = 0.24; P = 0.006). Further, 4 h serum IgG (R = –0.14; P = 0.026) and 24 h total blood serum protein (R = 0.21; P = 0.009) were correlated with lamb survival to 72 h. Conclusions: While the refractometer provided a crude measure of colostrum IgG and TP and was valuable in identifying lambs with low IgG transfer at 24 h, further research is required regarding analysis techniques to allow for reliable measures need to be refined. Implications: The use of refractometers to assess colostrum quality and intake could benefit researchers or producers who practice indoor lambing. The rapid assessment of colostrum in Merino ewes would provide valuable information regarding estimated immunoglobulin G (IgG) transfer and survival potential of lambs. Our research demonstrated that compared with laboratory tests, a hand-held refractometer was a crude measure of colostrum quality in ewes, and provided valuable information regarding estimated IgG transfer and lamb survival potential to 72 h. The use of a refractometer would be a cost-effective, easy-to-use tool for on-farm research or intensively managed flocks. [ABSTRACT FROM AUTHOR]

Background and Aim: Immunoglobulin G (IgG) concentration is high in goat colostrum, particularly in the first few hours after parturition, and this is important for the kid's immunity and growth. IgG levels vary depending on several factors, including breed, disease status, colostrum management, handling, and collection time postpartum. A handheld optical refractometer, an affordable instrument that is simple to use in the field, is used widely in dairy farms to measure total solids. However, it can also be applied to estimate colostrum IgG content on the basis of comparison with standard measurement methods, usually radial immunodiffusion. Studies comparing %Brix values in relation to IgG concentration measured using enzyme-linked immunosorbent assay (ELISA) in goats are limited. The present study aimed to evaluate the use of a handheld optical Brix refractometer for the measurement of IgG concentration in goat colostrum, compare results with those using ELISA, and estimate the %Brix cutoff value equating to low-quality colostrum. Materials and Methods: Colostrum samples were collected on day 0 from 21 goats (nine Black Bengal, six Saanen, and six of their crossbred offspring) and were frozen. Subsequently, they were analyzed for IgG concentration using a goat-specific ELISA test and Brix percentage using a handheld refractometer. The optimum %Brix cutoff value for the evaluation of colostrum quality was evaluated. Results: The mean IgG concentration and %Brix in colostrum were 10.60±0.64 and 25.0±0.9 mg/mL, respectively. There was a significant (p<0.01) correlation between %Brix and IgG concentration. For an IgG concentration of 6.9 mg/dl, the cutoff value for %Brix was 18.5, equating to high specificity (100%) but low sensitivity (50%). A higher %Brix cutoff value of 21.5 showed high specificity (95%) and high sensitivity (100%). Conclusion: A Brix refractometer can be used to estimate goat colostrum quality with a proposed %Brix cutoff value of <18.5%-21.5% for poor-quality colostrum. [ABSTRACT FROM AUTHOR]

In general, a sensor is used to monitor a single parameter only, and in many cases, a reference sensor is necessary to compensate the effect of temperature. Here, we demonstrate that a single supermode interferometer is capable of monitoring two parameters simultaneously. Said interferometer was fabricated with a segment of strongly coupled multicore fiber fusion spliced at the end of a standard single mode fiber. The free end of the multicore fiber was flat, thus, it behaved as a low reflectivity mirror whose reflection depended on the external refractive index. The reflection spectrum of our supermode interferometer consisted of well-defined periodic maxima and minima whose values and position varied when the interferometer was exposed to refractive index and temperature changes. In the Fourier domain, the changes of the interference pattern can be decoded easily. We demonstrate that the supermode interferometer here proposed can be useful to measure the thermo-optic coefficient of a sample. An important advantage of the device reported here is that the length of the multicore fiber is not determinant on the performance of the sensor. In addition, the device can be reused multiple times. [ABSTRACT FROM AUTHOR]

A fiber-optic refractive-index sensor using the phenomenon of surface plasmon resonance is created. A 1-nm layer of chromium and a 50-nm-thick gold film were deposited on a segment of a standard multimode optical fiber with partially removed cladding. Transmission spectra as a function of refractive index of an external medium in which the sensor was immersed were obtained. A minimum in transmission spectrum caused by excitation of a surface plasmon-polariton at the gold–analyte interface shifted upon variation of refractive index of the external medium. The sensor exhibited sensitivity of 1400 nm/RIU. [ABSTRACT FROM AUTHOR]

We describe the design, fabrication, and testing of a spectroscopic refractometer that employs plasmonic interferometry to measure the optical dielectric functions of materials in the visible range. The proposed device, dubbed a plasmonic refractometer, consists of an array of slit-groove plasmonic interferometers etched in a ~300 nm-thick metal film (silver or gold) with arm lengths varying in steps of 25 nm up to ~8 lm. The nano-groove in each interferometer is able to generate propagating surface plasmon polaritons efficiently in a broad wavelength range, without requiring prism- or grating-coupling configurations. An integrated microfluidic channel ensures uniform delivery of dielectric materials in liquid phase. Spectrally resolved plasmonic interferograms are generated by measuring light transmission spectra through the slit of each slit-groove plasmonic interferometer and plotting the normalized intensity as a function of arm length (0.26-8.16 μm) and incident wavelength (400-800 nm) for various combinations of metal/dielectric materials. Fits of the plasmonic interferograms with a surface plasmon interference model allow determination of the refractive index dispersion of a broad class of dielectric materials, over a wide range of wavelengths and dielectric constants. As proof of concept, we extract and report the dielectric functions of representative materials, such as silver, gold, water, methanol, and ethanol. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the efficacy of Brix refractometry and to compare the Brix value with semi-quantitative indicators such as total protein (TP), total protein in whey (TPw), glutaraldehyde coagulation time (GCT) and gamma-glutamyl transferase (GGT) enzyme activity for determining the quality of colostrum. Colostrum samples were collected from 38 Saanen goats just after parturition and on the first day (24 ± 4 hours) and second day (48 ± 4) after parturition. The Brix value, TP and TPw levels were measured with optic refractometers. The level of GCT was determined with a 10% glutaraldehyde solution. Immunoglobulin G (IgG) concentrations were measured with a goat IgG ELISA. All measurements decreased significantly after parturition. The IgG and Brix values on the day of parturition were 4719.28 ± 107.94 mg/dL and 20.55 ± 0.71, respectively. The TPw levels were lower than TP on all three days and a significant difference was detected on day 2. The IgG concentration was higher in the first-parity and secondparity goats compared with those older does. However, no differences were observed in the other characteristics of the colostrum. Litter size did not affect IgG or the other semi-quantitative tests. Correlation coefficients were higher than 0.8 Tp with TPw, and for the Brix value with both TP and TPw. Brix refractometry could be used to evaluate colostrum quality in Saanen goats and TPw is a more reliable indicator than TP. [ABSTRACT FROM AUTHOR]

The objectives of the present study were to examine the association between the brix refractometer% and ELISA assays in the assessment of colostrum-IgG content and in studying the factors affecting this content. Contents of IgG in colostrum samples of 132 healthy primiparous and multiparous Montbeliard x Holstein cross dairy cows kept in Egypt were evaluated using ELISA assay and brix refractometer%. The ELISA results showed that the IgG contents in the colostrum samples ranged from 5.96 to 114.84 mg/mL, with a mean of 57.07 mg/mL. Brix% results ranged from 15% to 35%, with a mean of 23.97%. The correlation and regression coefficients between ELISA(IgG) and brix% were significantly high (r=0.68 and r2=0.59, respectively). Prediction regression equation was ELISA(IgG)= 31.81+1.12(brix refractometer%). The effects of parity and season of calving on both ELISA(IgG) and brix% were significant. ELISA(IgG) and brix% were higher in cows = 3 lactations than those in the first and second lactations. Moreover, summer calving recorded higher ELISA(IgG) and brix% than autumn calving. Either ELISA(IgG) or brix% were not significantly affected by calf's sex, single/twin births, or history of cows' diseases. ELISA(IgG) and brix% had a significant positive correlation with calf's birth weights and gestation lengths, while they recorded a non-significant correlation with dry-period length. It can be concluded that a refractometer is a simple on-farm tool to assess colostrum quality. Its high correlation with the lab analytical assay of ELISA confirms the validity of using refractometers by researchers in colostrum studies. [ABSTRACT FROM AUTHOR]

Featured Application: Probe-like, multi-channel fiber biochemical sensor with ultra-small footprint. Resonant waveguide gratings (RWG) are widely used as on-chip refractometers due to their relatively high sensitivity to ambient refractive index changes, their possibility of parallel high-throughput detection and their easy fabrication. In the last two decades, efforts have been made to integrate RWG sensors onto fiber facets, although practical application is still hindered by the limited resonant peak intensity caused by the low coupling efficiency between the reflected beam and the fiber mode. In this work, we propose a new compact RWG fiber-optic sensor with an additional Fabry-Pérot cavity, which is directly integrated onto the tip of a single-mode fiber. By introducing such a resonant structure, a strongly enhanced peak reflectance and improved figure of merit are achieved, while, at the same time, the grating size can be greatly reduced, thus allowing for spatial multiplexing of many sensors on a tip of a single multi-core fiber. This paves the way for the development of probe-like reflective fiber-tip RWG sensors, which are of great interest for multi-channel biochemical sensing and for real-time medical diagnostics. [ABSTRACT FROM AUTHOR]

We describe a new measurement technique to determine the refractive index (RI) of solid particles by monitoring the simultaneous scattering of light from suspension with a camera and the value of the RI with a refractometer. Our immersion solid matching method is based on the solidification process of the liquid continuously changing the RI as a function of time. The principle of the determination is based on finding the RI matching point of the particle and the liquid during the solidification. The traditional liquid immersion method is based on a set of immersion liquids with different refractive indices, while the proposed method requires only a small amount of a single immersion liquid. The method was tested using calcium fluoride (CaF2) particles with a varnish immersion liquid. The RI value of CaF2 was obtained to be consistent with the literature values, thus indicating the proper functioning of the proposed procedure. [ABSTRACT FROM AUTHOR]

The problems of monitoring the state of flowing media with a simultaneous change in temperature and flow rate of the medium by more than two orders of magnitude are considered. A design of a flow-through refractometer is proposed for monitoring the state of transparent media in laminar and turbulent flow regimes, as well as at high flow rates and changes in the temperature of the medium by more than 200°C. The developed flow-through refractometer implements a method for measuring the refractive index, based on the principle of parallelism of two beams: the incident and transmitted through a pipeline with refraction at the boundaries of several media. The piping in the form of a cylindrical Plexiglas insert is part of the refractometer design. The design of the optical part of the refractometer with a vertical section of the pipeline eliminates the influence on the measurement of the refractive index of errors caused by multiple reflections of laser radiation from optical elements, the formation of voids or vortex flows in the pipeline. For the proposed refractometer there are no restrictions on the value of the measured refractive index of the flowing liquid, in contrast to the previously used industrial flow-through refractometers, the principle of operation of which is based on the phenomenon of total internal reflection of laser radiation at the interface of two media. The results of experimental studies of various media with the proposed refractometer are presented. [ABSTRACT FROM AUTHOR]