Cr2 O7 Research Articles

Textile industry manufacturing by-products induce human melanoma cell proliferation via ERK1/2 activation.

Textiles used to make clothing can represent a source, often ignored, of chemicals potentially noxious to both skin and the whole organism. Among the most frequently produced potentially noxious chemical manufacturing by-products are formaldehyde (FA), nickel (Ni) and hexavalent chromium (Cr); they are of potential clinical interest as all are known to be carcinogenic to humans and to be potent skin sensitizers. The aim of this study was to investigate, in vitro, effects of these potentially dangerous compounds on two different melanoma cell lines. In particular, attention was focused on A375P, a poorly metastatic and low invasive cell line and SK-MEL-28, a highly metastatic cell line. Effects of these compounds was evaluated on A375P and SK-MEL-28 cells. FA (1-5×10(-5) m), NiSO4 (10(-6) -10(-3) m), K2 Cr2 O7 (10(-7) -10(-6) m) effects on cell proliferation were evaluated by cell counting, while ERK pathway involvement was evaluated by Western blot analysis. Low concentrations of the chemicals, covering a range that corresponds to commonly accepted limits in textile production, induced a significant increase in cell proliferation concomitant with transient activation of phosphorylated ERK expression. Data obtained suggest that increasing attention must be focused on these by-products' potentially harmful effects in chemical manufacturing of clothes and accessories, that remain for long periods of time, in contact with human skin.

A Cationic Metal–Organic Framework Consisting of Nanoscale Cages: Capture, Separation, and Luminescent Probing of Cr2O72− through a Single‐Crystal to Single‐Crystal Process

Dichromate capture: A 3D cationic metal-organic framework consisting of distorted octahedral and tetrahedral cages was constructed by using Ag(I) and 4,4'-bis(1,2,4-triazole). The complex exhibits fast exchange, high trapping capacity, and good selectivity for Cr2 O7 (2-) through single-crystal to single-crystal transformation. The complex also features a bluish violet luminescence that is distinctly quenched after Cr2 O7 (2-) exchange.

Review on the acuteDaphnia magnatoxicity test – Evaluation of the sensitivity and the precision of assays performed with organisms from laboratory cultures or hatched from dormant eggs

Review on the acute<i>Daphnia magna</i>toxicity test – Evaluation of the sensitivity and the precision of assays performed with organisms from laboratory cultures or hatched from dormant eggs

Abundance and Dynamics of Soil Labile Carbon Pools Under Different Types of Forest Vegetation

ABSTRACT Soil organic matter (SOM) in forest ecosystems is not only important to global carbon (C) storage but also to sustainable management of forestland with vegetation types, being a critical factor in controlling the quantity and dynamics of SOM. In this field experiment soil plots with three replicates were selected from three forest vegetation types: broadleaf, Masson pine (Pinus massoniana Lamb.), and Chinese fir (Cunninghamia lanceolata Hook.). Soil total organic C (TOC), two easily oxidizable C levels (EOC1 and EOC2, which were oxidized by 66.7 mmol L−1 K2 Cr2 O7 at 130–140 °C and 333 mmol L−1 KMnO4 at 25 °C, respectively), microbial biomass C (MBC), and water-soluble organic C (WSOC) were analyzed for soil samples. Soil under the broadleaf forest stored significantly higher TOC (P ≤ 0.05). Because of its significantly larger total soil C storage, the soil under the broadleaf forest usually had significantly higher levels (P ≤ 0.05) of the different labile organic carbons, EOC1, EOC2, MBC, and WSOC; but when calculated as a percentage of TOC each labile C fraction of the broadleaf forest was significantly lower (P ≤ 0.05) than one of the other two forests. Under all the three vegetation types temperature as well as quality and season of litter input generally affected the dynamics of different organic C fractions in soils, with EOC1, EOC2, and MBC increasing closely following increase in temperature, whereas WSOC showed an opposite trend.

Kinetics of an Intratracheally Administered Chromium Catalyst in Rats

Chromium-based catalysts are used for the synthesis of polyethylene, but little is known about the hazard and biomonitoring possibilities of this type of chromium for workers who may be occupationally exposed to such compounds. Therefore, the bioavailability and toxicokinetics of chromium were studied in male Wistar rats after a single intratracheal instillation (2 ml/kg body weight) of various doses (1, 5, or 25 mg/kg body weight) of the catalyst (approximately 1% chromium bound to an amorphous silica matrix), either before (CAT-Cr[III]) or after (CAT-Cr[ VI]) heat treatment. The results were compared with those of equivalent amounts of two chromium salts (CrCl 3 and K 2 Cr 2 O 7 ). Each dose group was composed of three rats. The concentration of chromium was determined by atomic absorption spectrometry in urine (collected daily for 7 d) and in plasma, erythrocytes, lung, and liver tissue obtained 2 d (only highest concentration) and 7 d after dosing. On d 2, a significant increase in lung weight was found in the animals treated with the highest dose of the hexavalent Cr products. On d 7, on the basis of body weights, lung weights, and lung histology, there was no overt toxicity, except after the highest dose of CAT-Cr(VI). The elimination of all forms of chromium was apparently monoexponential, with calculated half-life elimination times in urine of 4-11 h for Cr(III) (CAT-Cr[III] and CrCl 3 ) and 8-21 h for Cr(VI) (CAT-Cr[VI] and K 2 Cr 2 O 7 ). On d 2, the erythrocytes Cr concentrations were significantly higher for the hexavalent Cr products than for the trivalent Cr products. After 7 d, the erythrocytes Cr concentrations were significantly increased above control values (3 w g/L) only in rats treated with the 2 highest doses of Cr( VI) compounds (12 and 64 w g/L for K2 Cr2 O7 , and 14 and 79 w g/L for CAT-Cr[VI]). The present study shows that intratracheally instilled Cr(VI) and Cr(III) have different toxicokinetic profiles and that the Cr(VI) catalyst has the same bioavailability and excretion kinetics as a water-soluble Cr(VI) salt. Exposure to chromium compounds could be monitored by measuring Cr concentrations in urine (shortly after exposure) and in erythrocytes (also at later time points after high Cr[VI] exposure).

The Rest Potentials of Platinum, Rhodium and Iridium Electrodes

The reduced and oxidized platinum, rhodium and iridium electrodes were alterna- tely dipped, as, cathode into the Solutions of 1 N H2SO4, 1 N HNO3, 1 N H2SO4 + 1/8 M K2Cr2O7, 1 N HNO3 +1 /8 M K2Cr2O7, 1 /4 M CrO3, 1 N H2SO4 + 10”2 M Ce (IV) SO4, İN NaOII, 1 N NaOH + 1 /8 M K2 Cr2 O7. The potentials with respect to time were mea- sured against a calomel electrode, (rest potentials). The electrodes were pretreated in two separate ways. The electrode, as anode, was dipped into a 1 N solution of H2SO4. A current of 200 mA was passed for a period of five minutes.Then the oxidized electrode was again dipped into a saıne type solution with continuous flow of nitrogen while being connected to a calomel electrode in short circuit (reduced electrode). The electrodes prepared according to the above procedure were again oxidized, anodically, for fifteen minutes under a current of 200 mA (oxidized electrodes). Using the same electrolyte, the rest potentials for platinum, rhodium and iridium were found to have different values. The rest potentials for -these metals in the Solutions mentioned above were very close to the cquilibrium potentials of the same metals in the oxidized state this indicates. That they were being oxidized in these Solutions.The time required for such metals to reach equilibrium was shortest for iridium next for rhodium and platinum.

Coherent Si growth on GaAs substrates by vapor phase deposition

Epitaxial Si layers with low dislocation density were grown on GaAs substrates by pyrolysis using disilane. The dislocation density evaluated from SECCO etching (HF:H2 SO4 :K2 Cr2 O7 =100 cc:50 cc:2g) was less than 104/cm2, which is lower by two orders of magnitude than that of the GaAs layer on Si substrates. We found that the electron mobility of Si layers on GaAs substrates could be raised by decreasing the growth rate and a high mobility value the same as that of a homoepitaxial layer was obtained, although the Si layers were contaminated by an arsenic impurity of 1018 cm−3 .

Determination of total organic‐C in soils by an improved chromic acid digestion and spectrophotometric procedure

Abstract An improvement to the Walkley‐Black wet digestion method for the rapid determination of organic carbon over the range 0.2–5.5% in air‐dry soil is described. It permits total recovery of the organic‐C in finely ground soil samples digested with the heat of dilution from mixing N K2 Cr2 O7 with concentrated H2SO4. in test tubes followed by external heating from a hot‐plate digestor. The organic‐C concentrations are determined directly, as the Cr product in diluted soil digests, by absorptiometry at 600 nm with calibration against similarly treated sucrose standards in solution. For the soils tested, there were negligible interferences from carbonates, wood charcoal, coke, Fe+2 and readily reducible Mn; Cl does not interfere with the organic‐C assay in non‐saline soils but for saline soils a correction based on 1/12 Cl‐ assay of the soil is necessary. The present method is compared with Tabatabai and Bremner's dry combustion procedure and Allison's manometric adaptation for calcareous soils. The pro...

EMBRYONIC RENAL INJURY: A POSSIBLE FACTOR IN FETAL MALNUTRITION

Chick embryo metabolism was monitored in a radlorespirometer where O2 consumption, CO2 production and 14CO2 from C-labeled proline, glutamate, aspartate and arginine was measured continuously during development. At nine days of development chemically dissimilar nephrotoxins (spermine, Na2 Cr2 O7, ethylene glycol monoethyl ether) were inoculated into the air sac which resulted in a temporary change in respiratory quotient from 0.71 to 0.85. At 18 days injured embryos consumed oxygen equal to that of a 14 day embryo and were 30-35% smaller in weight. Embryos with renal injury but matched with controls in terms of O2. utilization had a profound decrease in ability to metabolize the 14C-labeled substrates. Decreased ability to metabolize 14C-labeled proline was associated with decreased collagen formation. At 18 days there was pulmonary hypoplasia with sparce mesenchyme maturation but little residual evidence of renal injury that could be observed at ten days. It is suggested that renal injury during early fetal development may alter renal gluconeogenesis in addition to interfering with pathways essential for collagen formation, thereby contributing to fetal malnutrition and pulmonary hypoplasia. Supported by N.I.H. Grant HD08864.

INTRODUCTION OF CHELATE BOND TO FIBER

The fastness of dyeing with dispersed dyes depends on how deeply the particles of dyes are inserted. The microscopic test of the cross section of the dyed fiber has been widely used to know the distribution of dyes in fiber. Expecting that only the surface of polyester fiber dissolves in alkali treatment and leaves the inner part of the fiber unswollen, and a rigid stucture of Tetoron prevents. dyes from penetrating into inner part of fiber under ordinary condition, Alkali treatment of Cr treated Tetoron is continued till the combination of dyes with Cr at the surface of tetoron ends. under normal pressure.The polyester fiber used in this experiment was treated with K2 Cr2 O7 solution for 5hrs at 120°C and washed with water. Several portions of Cr treated tetoron, each 0.5g, were heated in 10% NaOH solution at 85°C changing the hours of the treatment and washed with water, and dyed with Sunchromine Pue Blure B. extra. Weight loss and absorption of dyes were determined. The relation between weignt losses and the time of alkali treatment is shown in Fig. I. The effect of absorption of dyes by Cr treated tetoron on the weight loss is shown in Fig. 2. Point A is a critical point where Cr is contained on fiber. From the weight loss at point A, the penetrated distance of Cr from the surface of fiber was calculated.