Optical density ratio method in spectrophotometric analysis

1975 ◽  
Vol 23 (4) ◽  
pp. 1412-1412
Author(s):  
V. K. Gudym
Keyword(s):  
Optical Density ◽  
Density Ratio ◽  
Spectrophotometric Analysis ◽  
Ratio Method ◽  
Optical Density Ratio

OPTICAL DENSITY RATIO OF THE SUBRETINAL FLUID IN CHOROIDAL MELANOMA AND METASTASIS

Retina ◽  
2019 ◽  
Vol 39 (4) ◽  
pp. 685-691 ◽  
Author(s):  
Ari Leshno ◽  
Vicktoria Vishnevskia-Dai ◽  
Adiel Barak ◽  
Dinah Zur ◽  
Shiran Gabai ◽  
...  
Keyword(s):  
Optical Density ◽  
Density Ratio ◽  
Choroidal Melanoma ◽  
Subretinal Fluid ◽  
Optical Density Ratio

Investigation on Modified Humic Substances Based Binders for Iron Ore Agglomeration

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Guihong Han ◽  
Tao Jiang ◽  
Guanghui Li ◽  
Yanfang Huang ◽  
Yuanbo Zhang
Keyword(s):  
Chemical Analysis ◽  
Humic Substances ◽  
Optical Density ◽  
Iron Ore ◽  
Structural Changes ◽  
Density Ratio ◽  
Hydroxyl Groups ◽  
Scanning Calorimetry ◽  
Optical Density Ratio

Characterization of modified humic substances based binders for iron ore agglomeration was examined by chemical analysis, optical density, Fourier transform infrared spectrum (FTIR), and thermogravimetry and differential scanning calorimetry (TG–DSC). Chemical analysis displays the proportion of fulvic acid (FA) to humic acid (HA) in the binder is 1:10. Compared with the HA, the FA possesses more functional groups. Meantime, optical density ratio analysis shows that the molecular weight and aromatization degree of the FA are smaller than those of the HA. FTIR spectra further confirm aromatic and aliphatic fractions are associated with various types of oxygen-rich groups including carboxyl and hydroxyl groups. TG–DSC and chemical analysis indicate structural changes of the binder including thermal decomposition, dehydroxylation and/or decarboxylation are caused during heating. The structural characterization of the binder ensures its good performance in the field of iron ore agglomeration.

scholarly journals Azimuthal-rotation sample holder for molecular orientation analysis

2020 ◽  
Vol 27 (5) ◽  
pp. 1167-1171
Author(s):  
Takayuki Harano ◽  
Yasuo Takeichi ◽  
Takuji Ohigashi ◽  
Daisuke Shindo ◽  
Eiji Nemoto ◽  
...  
Keyword(s):  
Optical Density ◽  
Density Ratio ◽  
Roller Bearing ◽  
Orientation Angle ◽  
Polarization Angle ◽  
X Rays ◽  
Sample Holder ◽  
Rotational Angle ◽  
Optical Density Ratio ◽  
Spherical Graphite

In this study, an azimuthal-rotation sample holder compatible with scanning transmission X-ray microscopy was developed. This holder exhibits improvement in the accuracy of rotation angles and reduces the displacement of the rotation axes during azimuthal rotation by using a crossed roller bearing. To evaluate the performance of the holder, the authors investigated the dependence of the optical density around the C K-edge absorption of π-orbital-oriented domains in natural spherical graphite on the rotational angle by using linearly horizontally and vertically polarized undulator radiation. Based on the dependence of the optical density ratio between C 1s → π* and 1s → σ* excitation on the polarization angle of the X-rays, the average two-dimensional orientation angle of the π orbital in each position in a natural spherical graphite sample was visualized.

Measurement of percent oxyhemoglobin in the microvasculature

1975 ◽  
Vol 38 (2) ◽  
pp. 321-327 ◽  
Author(s):  
R. N. Pittman ◽  
B. R. Duling
Keyword(s):  
Optical Density ◽  
Density Ratio ◽  
Optical Path Length ◽  
Optical Path ◽  
Cheek Pouch ◽  
Theoretical Treatment ◽  
Hamster Cheek Pouch ◽  
Particulate Suspensions ◽  
Optical Density Ratio

A new method is applied to the determination of percent oxyhemoglobin (percent saturation) in whole blood. The method is based on a theoretical treatment of light absorption and scattering by particulate suspensions and requires the measurement of optical densities (D) of blood at three closely spaced wavelengths. The optical density of red blood cell (RBC) suspensions was measured with a video microdensitometer and a linear relationship was found between percent saturation and the corrected optical density ratio, (D555 B)/(D546 B). For a given saturation, this ratio was independent of optical path length (12 mum-2 mm), hematocrit (3–50%), and RBC velocity (1.5–17 mm/s). The applicability to microvascular measurements has been assessed through the use of TV microdensitometry on micropipettes with flowing RBCs and on microvessels in the hamster cheek pouch.

Optical Density of Subretinal Fluid as a Predictive Biomarker for Eyes With Chronic Central Serous Retinopathy Treated With Eplerenone

2017 ◽  
Vol 2 (1) ◽  
pp. 6-11 ◽  
Author(s):  
Nisarg P. Joshi ◽  
Murtaza K. Adam ◽  
Wasim A. Samara ◽  
Abtin Shahlaee ◽  
Ehsan Rahimy ◽  
...  
Keyword(s):  
Optical Density ◽  
Pearson Correlation ◽  
Statistical Significance ◽  
Density Ratio ◽  
Subretinal Fluid ◽  
Percentage Change ◽  
Central Serous Retinopathy ◽  
Lower Baseline ◽  
Optical Density Ratio

Purpose: To investigate how the optical density ratio (ODR) of subretinal fluid (SRF) obtained by optical coherence tomography (OCT) in eyes with chronic central serous retinopathy (CSR), defined as symptoms >3 months, treated with eplerenone correlates with treatment response and visual outcomes. Methods: This retrospective, single-center observational study included patients with chronic CSR treated with eplerenone who had at least 6 weeks of follow-up. Eyes with poor-quality OCT scans, shallow SRF precluding sampling of optical density (OD), and macular pathology other than CSR were excluded. Optical density of the vitreous and SRF was measured using ImageJ and used to calculate ODR (ODR = ODSRF/ODVIT). Peak SRF height, foveal SRF height, central macular thickness (CMT), and Snellen visual acuity (VA) were measured. The Mann-Whitney U test was used to compare continuous variables. Pearson correlation coefficient was used to determine the statistical significance of applied linear regressions. Results: Twenty-three eyes of 23 patients met the inclusion criteria. Six (26%) eyes had complete resolution of foveal SRF (resolvers) with eplerenone treatment, and the remainder of patients had worsening or incomplete resolution (nonresolvers). Resolvers had significantly lower baseline logarithm of the minimum angle of resolution (logMAR) VA ( P < .01) than nonresolvers. There was a positive linear correlation between ODR and logMAR VA at baseline ( R2 = 0.208; P = .03) and follow-up ( R2 = 0.206; P = .03). A significant correlation between ODR and percentage change in CMT was found ( R2 = 0.263; P = .01). Linear correlations were not found between ODR and age, peak SRF height, and foveal SRF height (all P > .125). Conclusion: Lower baseline ODR was associated with improved percentage change in CMT and VA in patients treated with eplerenone for chronic CSR. Optical density ratio may represent a novel prognostic biomarker that may help determine which eyes with chronic CSR may respond better to eplerenone.

scholarly journals Effects of Azithromycin in Combination with Vancomycin, Daptomycin, Fosfomycin, Tigecycline, and Ceftriaxone on Staphylococcus epidermidis Biofilms

2009 ◽  
Vol 53 (8) ◽  
pp. 3205-3210 ◽  
Author(s):  
Elisabeth Presterl ◽  
Stefan Hajdu ◽  
Andrea M. Lassnigg ◽  
Alexander M. Hirschl ◽  
Johannes Holinka ◽  
...  
Keyword(s):  
Optical Density ◽  
Bacterial Growth ◽  
Staphylococcus Epidermidis ◽  
Density Ratio ◽  
Bacterial Count ◽  
Microtiter Plate ◽  
Antimicrobial Treatment ◽  
Flat Bottom ◽  
Initial Inoculum ◽  
Optical Density Ratio

ABSTRACT Staphylococcal biofilms on surgical implants are the underlying cause of a lack of response to antimicrobial treatment. We investigated the effects of vancomycin (VAN), daptomycin (DAP), fosfomycin (FOS), tigecycline (TGC), and ceftriaxone (CRX), alone and in combination with azithromycin (AZI), on established biofilms of Staphylococcus epidermidis. Biofilms were studied using the static microtiter plate model with established S. epidermidis biofilms, with an initial inoculum of 106/ml in 96-well polystyrene flat-bottom microtiter plates. Biofilms were inoculated with VAN, DAP, FOS, TGC, or CRX at two concentrations, alone or in combination with AZI (2, 512, or 1,024 mg/liter). To assess the reduction in biomass, the optical density ratio (ODr), calculated as (optical density [OD] of the treated biofilm)/(OD of the untreated biofilm, taken as 1), was used. For antibacterial efficacy, the viable bacterial count was used. Reductions in the biofilm ODr were observed for VAN (15 and 40 mg/liter) and FOS (200 mg/liter) only (ODr [mean ± standard deviation] for VAN at 15 and 40 mg/liter, 0.77 ± 0.32 and 0.8 ± 0.35, respectively; ODr for FOS at 200 mg/liter, 0.78 ± 0.26; P < 0.05), but not for DAP (2 and 5 mg/liter), TGC (0.2 and 2 mg/liter), or CRX (600 and 2,400 mg/liter). The addition of AZI had no further effect on the ODr, but a significant reduction of bacterial growth was achieved with high doses of AZI plus TGC or AZI plus CRX (a 3-log count reduction for AZI at 1,024 mg/liter plus CRX at 600 mg/liter and for AZI at 512 or 1,024 mg/liter plus CRX at 2,400 mg/liter; a 2-log count reduction for AZI at 512 or 1,024 mg/liter plus TGC at 2 mg/liter [P < 0.05]). No significant reduction in bacterial growth was observed for FOS (50 and 200 mg/liter), DAP (2 and 5 mg/liter), or TGC (0.2 mg/liter) in combination with AZI. None of the antibiotics at either concentration reduced the bacterial count of the biofilms when used alone. Thus, the use of a combination of AZI plus TGC, FOS, or CRX at high concentrations has little effect on biofilm density but significantly reduces bacterial growth.

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