Surface Acidity of Amorphous Aluminum Hydroxide

The surface acidity of synthetic amorphous AI hydroxide was determined by acid/base titration with several complementary methods including solution analyses of the reacted solutions and XRD characterization of the reacted solids. The synthetic specimen was characterized to be the amorphous material showing four broad peaks in XRD pattern. XRD analyses of reacted solids after the titration experiments showed that amorphous AI hydroxide rapidly transformed to crystalline bayerite at the alkaline condition （pH〉10）. The solution analyses after and during the titration Ksp=^aAl^3＋/aH^＋^3 ,was 10^10.3. The amount of consumption of added acid or base during the titration experiment was attributed to both the protonation/deprotonation of dissolved AI species and surface hydroxyl group. The surface acidity constants, surface hydroxyl density and specific surface area were estimated by FITEQL 4.0.

Spectroscopic study on variations in illite surface properties after acid-base titration

FT IR, Raman microscopy, XRD, 29 Si and 27 Al MAS NMR, were used to investigate changes in surface properties of a natural illite sample after acid base potentiometric titration. The characteristic XRD lines indicated the presence of surface Al Si complexes, preferable to Al(OH) 3 precipitates. In the microscopic Raman spectra, the vibration peaks of Si O and Al O bonds diminished as a result of treatment with acid, then increased after hydroxide back titration. The varied ratio of signal intensity between IV Al and VI Al species in 27 Al MAS NMR spectra, together with the stable BET surface area after acidimetric titration, suggested that edge faces and basal planes in the layer structure of illite participated in dissolution of structural components. The combined spectroscopic evidence demonstrated that the reactions between illite surfaces and acid leaching silicic acid and aluminum ions should be considered in the model description of surface acid base properties of the aqueous illite.

Early Pregnancy Diagnosis by Serum Acid Titration in Three Sheep Breeds

[ Objective] Earlier identification of pregnant and non-pregnant animals post mating can greatly improve reproductive efficiency and pregnancy rate and decrease the interval between services. The experiment was conducted to develop a rapid and simple early pregnancy diagnostic method in sheep. [Method] The eady pregnancy diagnosis was conducted with serum acid titration in 1 317 female sheep （Duolang sheep, Cele sheep and Karakul sheep） after 16 -30 d post artificial insemination. [Result] After the serum acid titration, 1 128 pregnant ewes and 189 non-pregnant ewes were detected in the three sheep breeds. Compared with the actual pregnancy detection, the coincidence rate of pregnancy was 89.88% （1 013/1 128） ; the coincidence rate of non-pregnancy was 96.83% （183/189） ; and the total coincidence rate was 90.81% （1 196/1 317）. Chi-square test analysis showed that no significant difference （P 〈 0.05） was found between the three sheep breeds or between any two breeds. [ Conclusion ] This serum acid titration is a simple, convenient and highly accurate method for early pregnancy diagnosis in sheep, which shows highly practical and popularizing value.

The pH and Titratable Acidity of Still and Sparkling Flavored Waters: The Effects of Temperature and Storage Time

Statement of the problem: Flavored waters have become increasingly popular in the Trinidadian retail market. There is a paucity of literature on the erosive potential of these products on dental hard tissue. Purpose: This study 1) evaluated the pH and titratable acidity of popular still and sparkling flavored waters in the Trinidadian marketplace and 2) evaluated the effect of time and temperature on pH and titratable acidity. Materials and methods: A calibrated pH meter was used to measure pH at baseline (T0), at one week of storage (T1) and at one month of storage (T2). Titratable acidity was determined using 0.1 M sodium hydroxide until a neutral pH of 7 was attained. Results: All tested flavors of both still and sparkling water demonstrated pH well below the critical pH of 5.5. Reduced temperature and time in storage caused varying degrees of change in both pH and titratable acidity. Generally, the largest changes in titratable acidity occurred for sparkling varieties of water. Conclusion: The still and sparkling flavors of water tested are potentially very erosive to dental hard tissue.

DIRECT TITRATION OF VERY WEAK ACIDS(BASES)IN AQUEOUS SOLUTION WITH STRONG BASES(ACIDS)USING VISUAL END-POINT INDICATION WITHOUT INDICATOR

This paper reports a new method of titration for very weak acids and bases using the appearance of incisions on oscillopolarogram to indicate the end-point.This method has the advantages of rapidity,simplicity,no indicator needed as well as good precision.

QUANTITATIVE ANALYSIS OF VERY WEAK ACID AND BASE BY pH-FIXED TITRATION METHOD

pH-fixed titration method for the determination of weak acids and bases has been studied in this paper.It is not necessary to know the ionization constant of weak acid or base and the concentration of titrant. This method had been applied to determine phenol,4-aminoantipyrine and glycine,whose ionization constants range from 10^(-10)to 10^(-12).The results were satisfactory.

The Effect of High Day and Low Night Temperature on Pollen Production, Pollen Germination and Postharvest Quality of Tomatoes

Temperature integration where high day temperatures are compensated by lower night temperatures is one strategy that can be used to reduce energy consumption in greenhouses. Crop tolerance to temperature variation is a prerequisite for using such a strategy. Greenhouse experiments were conducted on tomatoes cvs, Capricia, Mecano and Cederico in order to investigate the effect of different day/night temperature regimes (24/17, 27/14 and 30/11℃) where the same mean temperature was maintained for the production and germination of pollen. In addition, fruit quality as determined by fruit firmness, dry matter content, soluble solids, titratable acids, and pH was examined at harvest and after seven and 14 days of storage. The 30/11℃ treatment significantly increased pollen production and germination compared to the 24/17℃ treatment, while the 27/14℃ treatment was generally in between the other two treatments. Fruits grown at the 27/14℃ treatment were significantly firmer, while fruits grown at 24/17℃ had higher dry matter content, soluble solids, and titratable acids compared to the other treatments. There were significant differences between cultivars with respect to firmness, dry matter, titratable acidity, and pH. The quality of the fruits changed during storage, but the storability of the tomatoes was not affected by preharvest temperature treatments. The overall conclusion was that the 27/14℃ treatment was superior to the other two temperature treatments with respect to the studied parameters.

Lycopene Concentration and Physico-Chemical Properties of Tropical Fruits

In this study, the lycopene concentration and physico-chemical properties of tropical fruits in ripe for immediate consumption was evaluated. Chonto tomatoes had greater lycopene contents than Milano or Long Life Milano tomatoes, 107 as against 89 and 58 μg/(g fresh weight), respectively

Post-harvest storage of lime fruits (Citrus aurantifolia) following high humidity and low temperature in a modified brick wall cooler

The use of a modified brick wall Evaporative Cooling Chamber(ECC)for extending the shelf life of limes(Citrus aurantifolia)was compared with ambient storage.The shelf life inside of the ECC was extended by five to twenty days relative to ambient storage.The inside temperatures were about 4-6℃less than the ambient temperatures,and humidity was about 10%-20%higher.Study was conducted to check the weight loss and freshness of lime fruits,and data were observed daily.Weight loss in limes kept inside the chamber for ten days was 1.8%and in ambient conditions it was around 9.8%.The color of the fruit changed to yellowish inside the ECC and the control which was kept outside became unmarketable.ECC storage did not adversely affect fruit firmness,or the percentage of soluble solids or titratable acidity of the juice.The modified ECC does not require mechanical or electrical energy input and can be constructed with locally available material by unskilled labour.

Determining short chain fatty acids in sewage sludge hydrolysate: A comparison of three analytical methods and investigation of sample storage effects

In anaerobic digestion, the production of short-chain fatty acids （SCFAs） can be beneficial or harmful to the overall process, depending on the concentration of accumulated acids. Therefore, the accurate determination of the SCFA concentration in both fresh and stored sludge hydrolysates is important. To select a suitable method for monitoring SCFAs during the anaerobic digestion of sewage sludge, the accuracy of three available analytical methods, including 5 pH point acid titration （TITRA5）, gas chromatography （GC）, and spectrophotometry, were compared in the present study. The results revealed that TITRA5 and GC displayed better agreement in the achieved measurements and higher precision and accuracy than the spectrophotometric assay, as supported by the application of different statistical models. TITRA5 excelled in titrating unfiltered hydrolysate while simultaneously measuring the alkalinity, whereas the GC method provided detailed information on the contribution of different fatty acids to the total acidity. In contrast, the spectrophotometric assay suffered from many forms of interference, depending on the sample＇s matrix. SCFA production followed the pattern of enzymatic reactions and fitted the Michaelis-Menten model. In addition to promoting TITRA5 as an accurate and robust analytical tool for routine SCFA analyses, this comparative study also demonstrated the possibility of storing hydrolysate samples at different temperatures and durations without altering the SCFA measurements.