Citric Acid

Silica gel was chemically modified with an N-acyl-N~-benzoylthiourea group. This material behaved as a selective means of preconcentrating Cu(II), Zn(II) and Cd(lI) from ethanol by the column technique. Ethanolic solutions having 6 gmol of the metal ions were percolated through the column and retentions of 100% were achieved for all metals. Zinc and copper were eluted quantitatively from the column bed with 5mL of ethanolic 0.1 molL -1 (for Zn) and 0.9 mol L -1 (for Cu) citric acid. Cadmium was recovered totally with 60 mL of ethanolic 2.0 tool L -1 citric acid. The modified silica was shown to be chemically stable after various adsorption-elution cycles (at least twenty).

An experiment was conducted to find out the suitable preservative solution which provides the longest vase life for yellow gladiolus against eight preservative solutions coded from T 0 to T 7 and these were T 1 : 100-ppm silvar thiosulphate (STS); T 2 : 3% sucrose + 100-ppm citric acid (CA); T 3 : 3% sucrose + 100-ppm salicylic acid (SA); T 4 : 3% sucrose + 100-ppm STS; T 5 : 5% sucrose + 100-ppm CA; T 6 : 5% sucrose + 100-ppm SA; T 7 : 5% sucrose + 100-ppm STS with T 0 : Control (Tap water). T 4 treatment provided maximum spike diameter (13.9 mm) and floret opening (96.8%) at 12 th days after treating, maximum days to basal floret senescence (12.4), maximum no. of floret open during basal floret senescence (10.5), maximum solution absorption (47.8 ml/spike), maximum vase life (21.5 days) with minimum fresh weight loss (25.1%) and floret wilting (29.3%) at 12 th days after treating which was closely followed by T 3. However, incidence of stem rotting was not in T 2 , T 3 and T 4. Blend solutions of STS/SA (100-ppm) and 3% sucrose is recommended to use for the maximization of the postharvest life of yellow gladiolus.

Chromium (Cr) toxicity is widespread in crops grown on Cr-contaminated soils and has become a serious environmental issue which requires affordable strategies for the remediation of such soils. This study was performed to assess the performance of citric acid (CA) through growing Brassica napus in the phytoextraction of Cr from contaminated soil. Different Cr (0, 100, and 500 μM) and citric acid (0, 2.5, and 5.0 mM) treatments were applied alone and in combinations to 4-week-old seedlings of B. napus plants in soil under wire house condition. Plants were harvested after 12 weeks of sowing, and the data was recorded regarding growth characteristics, biomass, photosynthetic pigments, malondialdehyde (MDA), electrolytic leakage (EL), antioxidant enzymes, and Cr uptake and accumulation. The results showed that the plant growth, biomass, chlorophyll contents, and carotenoid as well as soluble protein concentrations significantly decreased under Cr stress alone while these adverse effects...

Although calcium supplementation can cause hypercalciuria, the risk of nephrolithiasis has been shown to decrease rather than increase among subjects who had a higher calcium intake. Hypercalciuria is also a well-established side effect of calcitriol administration. However, the risk of nephrolithiasis is not well de®ned. The present study was undertaken to prospectively determine the effect of calcium with or without calcitriol on physicochemical risk factors associated with calcium oxalate nephrolithiasis in Thai postmenopausal women with osteoporosis. Subjects consisted of 53 Thai women more than 10 years postmenopausal who were randomly allocated to receive 750 mg of calcium carbonate supplement alone (n = 28) or 750 mg of calcium carbonate plus 0.5 mg calcitriol (n = 25) daily. Mean Ô SEM for age was 65.3 Ô 1.1 years, body weight 53.5 Ô 1.3 kg. Urine samples for biochemical assays were collected at baseline and 3 months after treatment. Supersaturation for calcium oxalate stone formation was assessed from the 24 h urine constituents by the Tiselius's index, AP(CaOx). Three months of calcium supplement alone resulted in a modest, but not signi®cant, increase in urinary calcium (baseline, 2.90 Ô 0.43 mmol/day; after treatment 3.58 Ô 0.54 mmol/day) with no change in urinary oxalate, citrate or magnesium. In contrast, calcium together with calcitriol caused a signi®cant increase in urinary calcium (baseline, 2.87 Ô 0.41 mmol/day; after treatment, 4.08 Ô 0.57 mmol/day; p50.05). No signi®cant change in other urine constituents after treatment with calcium and calcitriol was detected. Therefore, AP(CaOx) did not signi®cantly increase either after calcium alone (baseline, 1.17 Ô 0.39; after treatment, 1.36 Ô 0.28) or after calcium plus calcitriol (baseline, 1.09 Ô 0.17; after treatment, 1.09 Ô 0.19). However, after treatments, 12 subjects (23%) ± 6 receiving calcium supplement alone and 6 receiving calcium plus calcitriol supplement ± had high AP(CaOx) values (greater than the upper limit of 95% CI for AP(CaOx) derived from non-stone-forming Thai women). The post-treatment/baseline ratio was 3.21 Ô 0.74 for urinary calcium, 1.01 Ô 0.19 for urinary oxalate, and 2.23 Ô 0.42 (median 1.15) for AP(CaOx). The post-treatment/baseline ratio of calcium, but not for urinary oxalate, had a signi®cant correlation with the post-treatment/baseline ratio of AP(CaOx). Our ®ndings suggest that the alteration in the risk of calcium oxalate nephrolithiasis based on urinary composition is related to the alteration in urinary calcium. The risk of calcium oxalate nephrolithiasis does not increase signi®cantly after calcium or combined calcium and calcitriol supplement in the majority of postmenopausal women with osteoporosis.

The interaction of Ca 2+ -ions with sildenafil citrate (Viagra) leads to the precipitation of a new polymorph variety of sildenafil base. Under the same conditions Mg 2+ , Zn 2+ and Cd 2+ ions form structurally related crystalline complexes of the composition Me 2+ C 28 H 34 N 6 O 11 S.