scholarly journals pH and Redox Induced Color Changes in Protein Crystals Suffused with Dyes

Crystals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 126 ◽  
Author(s):  
Alexander McPherson
Keyword(s):  
Ascorbic Acid ◽  
Redox Potential ◽  
Mother Liquor ◽  
Ph Sensitive ◽  
Protein Crystals ◽  
Ph Changes ◽  
Color Changes ◽  
Chemical Factors ◽  
Diffusion Rates ◽  
Over Time

Protein crystals, otherwise usually colorless, can be stained a variety of hues by saturating them with dyes, by diffusion from the mother liquor or co-crystallization. The colors assumed by dyes are a function of chemical factors, particularly pH and redox potential. Protein crystals saturated with a pH sensitive dye, initially at one pH, can be exposed to the mother liquor at a second pH and the crystal will change color over time as H3O+ ions diffuse through the crystal. This allows diffusion rates of H3O+ through the crystal to be measured. Diffusion fronts are often clearly delineated. Similar experiments can be carried out with redox sensitive dyes by adding reductants, such as ascorbic acid or dithionite, or oxidants such as H2O2, to the crystal’s mother liquor. Presented here are a number of experiments using pH or redox sensitive dye-saturated protein crystals, and some experiments using double dye, sequential redox–pH changes.

A Mechanism for Reversibly Pausing a Self-Immolation Cascade in Response to pH Changes

2019 ◽  
Author(s):  
Derrick Roberts ◽  
Ben S. Pilgrim ◽  
Tristan Dell ◽  
Molly Stevens
Keyword(s):  
Local Environment ◽  
Chemical Signals ◽  
Ph Sensitive ◽  
First Report ◽  
Ph Changes ◽  
Self Immolation

We describe the first report of a self-immolation cascade that can be reversibly paused and reactivated in response to pH changes. This system employs a triazole-based self-immolative linker, which expresses a pH-sensitive intermediate during its elimination sequence. This allows the system to respond to pH cues within its local environment, thus establishing a new way to gate self-immolative release using fluctuating or transient chemical signals.<br>

scholarly journals Influence of chitosan coatings with citric essential oil on the shelf-life of minimally processed mango (Mangifera indica L.)

2015 ◽  
Vol 68 (2) ◽  
pp. 7679-7688
Author(s):  
Fabián Rico Rodríguez ◽  
Carolina Gutiérrez Cortés ◽  
Consuelo Díaz Moreno
Keyword(s):  
Weight Loss ◽  
Ascorbic Acid ◽  
Shelf Life ◽  
Mangifera Indica ◽  
The Other ◽  
Soluble Solids ◽  
Total Acidity ◽  
Minimally Processed ◽  
Color Changes ◽  
Sensory Acceptance

Demand for minimally processed fruits have increased due to their nutritional value and an increasing change in consumption habits. Physicochemical, microbiological, structural and sensory changes were determined in minimally processed mangoes (MPM) with chitosan (CH) edible coatings and lemon and orange essential oils (EOL). The MPM was first dipped in citric acid and a texturizing solution and then dipped in CH and lemon or orange EOL coatings. Weight loss, sensory acceptance, total soluble solids, total acidity, ascorbic acid, color changes, firmness and elasticity, and microbiological changes were quantified for 11 days of refrigerated storage. The CH and lemon EOL coating had more acceptance than the other treatments. No differences were found (p>0.05) for weight loss, total acidity, ascorbic acid, firmness or elasticity. There was a high amount of total phenols due to the EOL composition, as well as a high antioxidant capacity in the early days of storage. This characteristic decreased in the final days of the study. There was a decrease in the microbial charge for the lemon EOL treatment, as compared to the other samples. The CH and lemon EOL coating helped to maintain the shelf-life of the MPM for 11 days of storage without affecting the sensory acceptance. The CH and Orange EOL coating did not have an effect on the MPM physicochemical attributes; however, the sensory acceptance was negatively affected with off-flavors conferred to the MPM.

Quantifying Coronal Permanent Tooth Discoloration Caused by Different Pulpotomy Materials

2021 ◽  
Vol 45 (5) ◽  
pp. 306-311
Author(s):  
Hanaa Azem ◽  
Sigalit Blumer ◽  
Benjamin Peretz ◽  
Sohad Haj-Yahya ◽  
Shlomo Elbahary
Keyword(s):  
Color Space ◽  
Mineral Trioxide Aggregate ◽  
Permanent Tooth ◽  
Control Group ◽  
Major Drawback ◽  
Tooth Structure ◽  
Color Changes ◽  
Base Materials ◽  
Tooth Discoloration ◽  
Over Time

Introduction: Bioceramic materials, gray and white mineral trioxide aggregate (GMTA, WMTA), have been shown to have high rates of success in various endodontic applications. A major drawback is their tendency to discolor teeth compared to Biodentine (BD), that has been claimed not to discolor teeth. The aim of this study was to compare tooth discoloration after applying different pulpotomy base materials (BD, GMTA and WMTA). Study design: Forty human incisors teeth were used in this study. Coronal access was achieved by a Tungsten Carbide drill, and the pulp chambers were accessed and chemo-mechanically debrided. Each material was placed in the pulp chamber, up to the cervical sectioning level. All specimens were incubated at 37°C and 100% humidity for three months and have been evaluated before the study and weekly. Color was assessed according to the CIE L*a*b* color space system. Results: ΔE of all experimental groups (GMTA, WMTA and BD) were significantly different from the control group at all time points (P&lt;0.05). Color changes in the GMTA and WMTA groups, had no statistically significant differences, but showed higher discoloration compared to BD group in the cervical part of the crown, since week 1 (P&lt;0.05). WMTA group showed significant discoloration in the cervical part as of week 1 (P&lt;0.05), and gradually increased over time (Figure 2). BD group showed no significantly discoloration over time. GMTA group showed the significant discoloration at week 1 and week 14 (P&lt;0.05). Conclusions: both GMTA and WMTA pulpotomy materials may discolor tooth structure over time in an extracted permanent anterior tooth model. When choosing bioceramic pulpotomy material, BD may be preferable in esthetic area.

scholarly journals Using Redox Potential as a Feasible Marker for Banked Blood Quality and the State of Oxidative Stress in Stored Red Blood Cells

2020 ◽  
Author(s):  
Rodney C Daniels ◽  
Hyesun Jun ◽  
Robertson D Davenport ◽  
Maryanne M Collinson ◽  
Kevin R Ward
Keyword(s):  
Oxidative Stress ◽  
Redox Potential ◽  
Red Blood Cells ◽  
Healthy Volunteers ◽  
Blood Cells ◽  
Storage Time ◽  
Cell Function ◽  
Venous Blood ◽  
Functional Changes ◽  
Over Time

Abstract Background Stored Red Blood Cells (RBCs) may undergo oxidative stress over time, with functional changes affecting critical tasks such as oxygen delivery. Central to these changes are oxidation-reduction (redox) reactions and the redox potential (RP) that must be maintained for proper cell function. RP imbalance can lead to oxidative stress that may contribute to storage lesions and transfusion-related morbidities. Direct measures of RP may allow for evaluation of erythrocyte quality and enable corrections of RP prior to transfusion. Methods Multiple random RBC segments were tested, ranging in age from 5 to 40 days at 5 day intervals. RP was recorded by measuring open circuit potential of RBCs using novel nanoporous gold electrodes with Ag/AgCl reference. RP measures were also performed on peripheral venous blood samples from 10 healthy volunteers. RP measures were compared between groups of aged RBCs, and with volunteer blood. Results Stored RBCs show time-dependent increases in RP. There were significant differences in Day 5 RP compared to all other groups (p≤0.005), Day 10-15 vs ages ≥ Day 20 (p≤0.025), Day 20-25 vs Day 40 (p=0.039), and all groups compared to healthy volunteers. RP became more positive over time suggesting ongoing oxidation as RBCs age. However, storage time alone does not predict the ultimate RP value measured from a given unit.Conclusions There are significant differences in RP between freshly stored RBCs and all others, with RP becoming more positive over time. However, storage time alone does not predict RP, indicating RP screening may be important independent of storage time and may serve as a marker of RBC quality and state of oxidative stress. RP measurements may also provide a target by which to restore RP balance in aged pRBCs, improving their clinical effectiveness while reducing associated morbidities.

scholarly journals Changes in the contents of kaempherol, quercetin and L-ascorbic acid in sea buckthorn berries during maturation

2000 ◽  
Vol 9 (1) ◽  
pp. 17-22 ◽  
Author(s):  
N. JEPPSON ◽  
G. XIANGQUN
Keyword(s):  
Ascorbic Acid ◽  
High Performance Liquid Chromatography ◽  
Liquid Chromatography ◽  
High Performance ◽  
Sea Buckthorn ◽  
Maturation Stages ◽  
The Mean ◽  
Over Time

The contents of kaempherol, quercetin and L-ascorbic acid in sea buckthorn berries were measured at different maturation stages using High Performance Liquid Chromatography (HPLC) methods. The content of ascorbic acid decreased over time with significant differences between sampling dates for the five cultivars studied. The mean decrease was 25% in 19 days, from 1.48 to 1.10 g kg-1. Quercetin decreased whereas kaempherol increased during maturation. Among three studied cultivars, the decrease in quercetin was significant (from 0.028 to 0.014 g kg-1) in 'Otradnaja', where as the increase (from 0.012 to 0.016 g kg-1) in kaempherol was significant in the others two, 'Prozratnaja' and 'Gibrid Pertjik'.;

Quantifying Coronal Primary Tooth Discoloration Caused by Different Pulpotomy Materials

2020 ◽  
Vol 44 (3) ◽  
pp. 142-147
Author(s):  
S Elbahary ◽  
R Bercovich ◽  
N Flaisher-Salem ◽  
H Azem
Keyword(s):  
Color Space ◽  
Mineral Trioxide Aggregate ◽  
Primary Tooth ◽  
Control Group ◽  
Major Drawback ◽  
Tooth Structure ◽  
Color Changes ◽  
Base Materials ◽  
Tooth Discoloration ◽  
Over Time

Introduction: Bioceramic materials, gray and white mineral trioxide aggregate (GMTA, WMTA), have been shown to have high rates of success in various endodontic applications. A major drawback is their tendency to discolor teeth. Biodentine (BD), a recenlty developed bioceramic material, has been claimed not to discolor teeth. The aim of this study was to compare tooth discoloration after applying different pulpotomy base materials (BD, GMTA and WMTA). Methods: Forty human fully developed primary incisors teeth were used in this study. Coronal access was achieved by a Tungsten Carbide drill, and the pulp chambers were accessed and chemo-mechanically debrided. Each material was placed in the pulp chamber, up to the cervical sectioning level. All specimens were incubated at 37°C and 100% humidity for 14 weeks and have been evaluated before the study and weekly. Color was assessed according to the CIE L*a*b* color space system. Results: The ΔE (delta E) of all experimental groups (GMTA, WMTA and BD) were significantly different from the control group at all time points. Color changes in the GMTA and WMTA groups showed significantly higher discoloration compared to BD group in the cervical part of the crown, since week 1. WMTA group showed significant discoloration in the cervical part as of week 1, and gradually increased over time. BD group showed no significant discoloration over time. GMTA group showed the most significant discoloration at week 1 and week 14 (P&lt;0.05). Conclusions: both GMTA and WMTA pulpotomy materials may discolor tooth structure over time in an extracted primary anterior tooth model. When choosing bioceramic pulpotomy material, BD may be preferable, mainly in esthetic area.

The transfer of protein crystals from their original mother liquor to a solution with a completely different precipitant

1988 ◽  
Vol 21 (5) ◽  
pp. 426-429 ◽  
Author(s):  
H. A. Schreuder ◽  
H. Groendijk ◽  
J. M. van der Laan ◽  
R. K. Wierenga
Keyword(s):  
Mother Liquor ◽  
Protein Crystals

pH-Sensitive Capsules as Intracellular Optical Reporters for Monitoring Lysosomal pH Changes Upon Stimulation

Small ◽  
2012 ◽  
Vol 8 (6) ◽  
pp. 943-948 ◽  
Author(s):  
Pilar RiveraGil ◽  
Moritz Nazarenus ◽  
Sumaira Ashraf ◽  
Wolfgang J. Parak
Keyword(s):  
Ph Sensitive ◽  
Lysosomal Ph ◽  
Ph Changes ◽  
Optical Reporters

Color changes in the red-green plates of the 50-year-old AO HRR color vision test

2006 ◽  
Vol 23 (3-4) ◽  
pp. 681-684 ◽  
Author(s):  
DAVID Y. LEE
Keyword(s):  
Color Vision ◽  
Chromaticity Diagram ◽  
Color Changes ◽  
Governmental Agencies ◽  
Wear And Tear ◽  
Color Vision Test ◽  
Cie Chromaticity ◽  
Changes Over Time ◽  
Over Time ◽  
Better Than

The original AO HRR color vision test has been considered by many as one of the best plate tests. It is still accepted by many governmental agencies for color vision certification. In their 1954 publication, Hardy, Rand, and Rittler stated that specially compounded inks were used for printing to avoid color changes with time. Fifty years later, it is both important and interesting to determine whether the wear and tear cause significant color changes. The chance finding of a never-used second edition offers an opportunity to evaluate the color changes. A GretagMacbeth Spectrolino spectrophotometer was used to measure the chromaticities of the never-used book, and an extensively used book. Four plates (#4, 7, 13, 16), selected randomly from the four red-green sections, were analyzed. The colored dots from each of the eight plates were plotted on a CIE chromaticity diagram. Isocolor lines were drawn to evaluate chromatic alignment. Chromaticities for plates #4 and 7 are significantly different between the two books. With regard to alignment with isocolor lines, the extensively used book is better than the never-used book for plate #4. There is significant misalignment on plate #7 for both books. Chromaticities for plates #13 and 16 are essentially identical between books, all with good alignment with isocolor lines. The overall comparison shows that the chromatic alignment characteristics of the extensively used book are not worse than the never-used book. Since colors in these plates have to be aligned with both the protan and deutan axes, any significant color changes would have disturbed this delicate requirement. The findings of many plates with good alignment, and the lack of differences on plates #13 and 16 between books, suggest that there are no significant color changes over time. Differences between books on plates #4 and 7 were likely the result of the original printing process.

scholarly journals INVESTIGATION OF THE INFLUENCE OF ASCORBIC ACID ON THE TITER OF LACTIC ACID BACTERIA AND TEST FERMENTATION

2021 ◽  
Vol 1 (38) ◽  
pp. 123-133
Author(s):  
I. Korniienko
Keyword(s):  
Ascorbic Acid ◽  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Redox Potential ◽  
Unsaturated Fatty Acids ◽  
Total Content ◽  
Correct Selection ◽  
Fermentation Time ◽  
Biochemical Processes

The use of modern biotechnological approaches in the field of baking allows to improve the quality of finished products, reduce the duration of the technological cycle and increase the functional properties of bread. The aim of the study was to study the effect of ascorbic acid on the intensity of fermentation processes during dough maturation. The task of the work is to establish the optimal amount of improver — ascorbic acid, taking into account organoleptic, microbiological and structural-mechanical quality indicators. The intensity of microbiological and biochemical processes during dough maturation (fermentation) directly depends on the concentration of hydrogen ions compared to the total content of acid-reactive products, as well as redox potential, titrated acidity and titer of fermentation microflora.The introduction of ascorbic acid in the amount of 0.1—0.12 g/kg of flour, the fermentation time of the dough was reduced from 270 to 225 minutes, the speed and completeness of redox reactions (redox potential  -50 mV) were increased. redox potential reactions catalyzed by the enzymes peroxidases and catalases are associated with the oxidation of unsaturated fatty acids, which promote the action of lipoxygenase by disrupting its inhibitor - hydrogen peroxide. Experiments have confirmed the activation of the fermenting microflora of the dough and the increase of its titer. Indicators of active (pH 4.66—4.51) and titrated acidity (6.0—6.5 degrees Turner) are within the limits that fully meet the optimal conditions for the cultivation of lactic acid bacteria, which indicates the correct selection of the amount of ascorbic acid and the composition of the nutritious flour mixture.

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