TCB Concentrations Research Articles

Biodegradable thermochromic polylactic acid (PLA) sensor

Abstract This study investigates the development of polylactic acid (PLA) by incorporating thermochromic black pigments (TCB) at varying concentrations of 0, 0.5, 1, 2 and 3 wt% through the process of melt blending. The color transition and reversion behaviors of the resulting specimens were examined at different temperatures (−10, 10, 30, 35 and 50 °C) using colorimetric analysis. Additionally, mechanical properties, thermal characteristic and thermal stability were assessed through tensile testing, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), respectively. The study revealed that an increase in TCB concentrations led to a reduction in lightness (L*). Higher pigment content enhanced thermochromic properties, resulting in more pronounced color changes. The total color difference (ΔE) remained reproducible over five cycles of heating and freezing, and this reproducibility persisted after thermal aging. Tensile strength and elongation at break exhibited improvement with increasing pigment content. Glass transition temperature (Tg) and melting temperature (Tm) of the thermochromic samples showed minimal reduction compared to that of neat PLA, which is 64.2 °C. Crystallinity degree (Xc) increased slightly by 0.2–0.92 %. The thermal stability of the PLA matrix was only marginally affected by the presence of thermochromic pigments.

Baseline assessment of water quality and ecological indicators in Penaeus vannamei farm wastewater along the Southeast coast of India

The present study aimed to investigate the water quality characteristics and the ecological indicators of wastewater of white legged shrimp Penaeus vannamei ponds along the Southeast coast of India. The wastewater samples were collected from 15 shrimp farms covering 11 districts located along the coastal line of Tamil Nadu and Puducherry, India. By adopting standard methods, the collected samples were subjected to analyses of physico-chemical and biological characteristics, especially the microbial load and metal and plankton composition. The nitrate-nitrogen, ammonia-nitrogen, THB, TCB, and Cu concentrations of the samples were found to exceed the permissible limit as recommended by WHO, USEPA, CPCB, and CAA. Principal component analysis and canonical correspondence analysis have suggested that the phosphate, nitrate, silicate, ammonia, and total phosphorus are the important chemical factors. The generated data would be of interest to farmers for their shrimp crop management vis-à-vis culture pond wastewater treatment.

Effects of 1,2,4-Trichlorobenzene on Photosynthetic Characteristics of Flag Leaf during Grain Filling Stage and Grain Yield of Two Rice Cultivars

A pot experiment was conducted, using two rice cultivars Ningjing 1 (TCB sensitive) and Yangfujing 8 (TCB tolerant), with five concentration treatments (0, 10, 20, 40, and 80 mg TCB per kg dry soil) to explore the responses of two rice cultivars to TCB, and provide the basis for the high, stable, and safe production of rice. The results indicated that significant differences were found in the effects of TCB treatments on grain yield and photosynthetic parameters of flag leaf between the two cultivars. Plant height, fresh weight, and yield were significantly increased, chlorophyll content, net photosynthetic rate, intercellular CO2 con- centration, transpiration rate, and qN were slightly increased, while Fv/Fm and Fv/Fo were slightly decreased in the low TCB con- centration (10 mg kg -1 ) treatment of Yangfujing 8. Under the same condition, the net photosynthetic rate, CO2 intercellular con- centration, transpiration rate, ΦPSII, Fv/Fm, Fv/Fo, qp, yield in Ningjing 1 were slightly declined with significant reduction of stomatal conductance. The photosynthetic characteristics, yield, plant height, fresh weight in Ningjing 1 were decreased signifi- cantly, while Yangfujing 8 showed more resistance and adaptation to TCB at 20 mg kg -1 . Both cultivars showed significant de- crease in growth, photosynthesis and yield in treatments with high TCB concentrations (40 and 80 mg kg -1 ), with the greater dec- rements in Ningjing 1. The effect of TCB on photosynthetic characteristics and yield of rice was not only related to TCB concen- tration, but also to cultivars. Low TCB levels slightly promoted the plant height, fresh weight, chlorophyll content, photosynthetic

Physiological and biochemical response of wheat seedlings to organic pollutant 1, 2, 4-trichlorobenzene

The growth and antioxidant defence responses in wheat (Triticum aestivum L.) seedlings grown hydroponically with 0 (control), 10, 20, 40 and 80 mg L−1 of 1, 2, 4-trichlorobenzene (TCB) were examined to better understand plant physiological and biochemical responses to chlorinated benzenes. Fresh and dry shoot weight, chlorophyll and soluble protein contents decreased significantly with increasing TCB concentration. In contrast, the rate of production of O2 - in the roots increased at lower TCB concentrations but decreased at higher concentrations. In addition, foliar electrolyte leakage and antioxidant defence activities increased linearly with increasing TCB concentration but were suppressed at higher concentrations in the roots. Taken together, the results support the hypothesis that antioxidant defence responses are an important component of plant responses to TCB, and oxidative damage appears to be a major factor leading to growth suppression in wheat exposed to higher TCB concentrations.

Effect of trichlorobenzene additive on the performance and morphology of polyfluorene and fullerene derivative bulk heterojunction solar cells

The influence of additive, namely 1,3,5-trichlorobenzene (TCB), on the morphology and performance of bulk heterojunction (BHJ) organic solar cells was studied based on a 1:2 (w/w) blend of benzothiadiazole/thiophene-based copolymers (PFTBzTT) to [6,6]-phenyl-C61 butyric acid methyl ester (PCBM). The active layers were deposited by spin-coating from solutions using chloroform, with different additive concentrations from 0 to 36 mg/ml. The addition of solvent additive into the polymer solution was able to improve the performance of BHJ solar cells. The maximum power conversion efficiency (%PCE) of 0.85% was obtained for a cell with the TCB concentration of 12 mg/ml after annealing at 180°C for 20 min. From atomic force microscopy (AFM) images, the films processed without TCB appear smoother than those with the TCB additive. A large extent of segregation was also observed in the films processed with a high TCB concentration. The optical images of the thin films suggest that the optimum concentrations of the additive cause the polymer self-organisation, resulting in some aggregation of large PCBM crystals. © 2011 Canadian Society for Chemical Engineering

Physiological Response to 1,2,4-Trichlorobenzene Stress of Different Rice Genotypes in Seedlings

1,2,4-Trichlorobenzene (TCB) has pervaded in industrial and agricultural production. Because of a series of problems caused by its stableness and fatalness, TCB has been added into the environmental pollutant list. In order to know how TCB affects the rice seed germination, seedling growth and its physiological characteristics, the seed germination, seedling biomass, soluble protein, and malnodialdehyde (MDA) contents, as well as activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in leaves and roots of seedlings treated with TCB were investigated in a sand culture experiment using rice cultivars, Xiangjing 20-18 (TCB tolerant genotype)and Siyang 1382 (TCB sensitive genotype). The results indicated that TCB had little effect on the seed germination rate and index, however caused the significant reduction of seedling biomass, with Xiangjing 20-18 being more affected than Siyang 1382. With TCB stress degree strengthening, soluble protein content of Xiangjing 20-18 leaves and roots presented an increasing tendency, while that of Siyang 1382 leaves decreased significantly, and that of its roots decreased too under treatment of high TCB concentration. O 2. producing velocity of leaves in two genotypes decreased firstly, then increased with increasing TCB concentration. That of Xiangjing 20-18 roots presented the same tendency, and significantly higher than the control at TCB≥0.6 mmol kg-1, while that of Siyang 1382 roots had no significant difference with that of the control. SOD activity of Xiangjing 20-18 leaves increased, and that of roots increased significantly. After TCB≥0.2 mmol kg-1,SOD activity of Xiangjing 20-18 leaves was significantly higher than that of the control, that of Siyang 1382 leaves and roots was not significantly different with that of the control. POD activity of Xiangjing 20-18 leaves increased firstly, then decreased, and that of roots was significantly higher than the control, while that of Siyang 1382 leaves and roots decreased significantly. CAT activity of Xiangjing 20-18 leaves was higher or significantly higher than that of the control, and that of Siyang 1382 was contrary to the result of Xiangjing 20-18. MDA content of leaves decreased firstly, then increased, being significantly higher than that of the control at high TCB concentration, and that of roots increased significantly in two genotype. In conclusion, lower reduction of seedling biomass, high protein content of leaves and roots, the better active oxygen's elimination ability and lower MDA content in plants would be considered as the physiological traits in TCB-tolerant genotypes of rice.

Intestinal bioavailability and biotransformation of 3,3′,4,4′-tetrachlorobiphenyl (CB 77) in in situ preparations of channel catfish following dietary induction of CYP1A

Previous studies with the catfish in situ perfused intestinal preparation have demonstrated a significant decline in the intestinal bioavailability of a coplanar polychlorinated biphenyl (PCB), 3,3′,4,4′-tetrachlorobiphenyl (CB 77)( 14C-TCB) dose in animals pre-exposed in vivo to TCB. This response was accompanied by CYP1A induction in the intestine, but little effect upon the oxidative metabolism of the subsequent in situ dose of [ 14C]-TCB. To ascertain the basis of these responses and the intestine specific contributions, the intestinal bioavailability and metabolism of [ 14C]-TCB were examined in the in situ intestinal preparation following in vivo exposure to β-naphthoflavone (BNF; 0, 10 or 50 mg BNF/kg diet for 10 days), BNF was selected as a known inducer of CYP1A and as a compound with a structure unlikely to influence or directly partake in diffusion based TCB concentration gradients. Appreciable amounts of [ 14C]-TCB molar equivalents (Meq) reached the perfused circulation of the intestinal preparation for all treatments. While BNF pre-exposure elicited induction of CYP1A activities aryl hydrocarbon hydroxylase (AHH) (9.2–12.5-fold) and elicited modest morphological changes (muciparous) in the intestine these changes were not associated with alterations in [ 14C]-TCB Meq bioavailability. [ 14C]-TCB metabolism in the intestinal mucosa ranged between 0.54 and 1.27%, for all treatments. As with bioavailability, intestinal metabolism of [ 14C]-TCB was not significantly influenced in either extent or profile by induction of CYP1A activity as associated with BNF treatment. Four metabolites were found in mucosal sample extracts of which three were tentatively identified as 2-OH-TCB, 4-OH-3,3′,4′,5-TCB, and 4,4′-diOH-3,3′,5,5′ tetrachlorobiphenyl. A fourth unknown metabolite presented chromatographic characteristics suggestive of another dihydroxylated metabolite. These data when examined alone and compared to the literature suggest that the intestine may metabolize [ 14C]-TCB slowly and independent of CYP1A, resulting in somewhat different profiles than published for other organs. In addition, it is likely that previous [ 14C]-TCB bioavailability findings in the perfused intestine may be based on TCB concentration gradients rather than biotransformation.

Short-term toxic effects of chlorobenzenes on broadbean (Vicia faba) seedlings

The root growth, changes in superoxide dismutase (SOD, EC 1.15.1.1) activity, malonyldialdehyde (MDA) and total soluble protein level of broadbean (Vicia faba) seedlings were researched at different soil concentrations of chlorobenzene (CB), 1,2,4-trichlorobenzene (TCB) and hexachlorobenzene (HCB). The results showed that root growth of seedlings was interrupted after 5 d of 50-200 microg x g(-1) TCB treatment. During a 3 d recovery period, root growth was, however, restored to some extent although there was a delay in returning to the control level. The total soluble protein content in seedlings increased with TCB concentration and duration of exposure. Effect of TCB stress on SOD activity in seedlings displayed a significant dose-effect relationship for 1-5 d of 50-200 microg x g(-1) treatment. When broadbean seedlings were placed in clean tap water for 3 d following exposure to 5 d of TCB stress to clear tap water for 3 d, SOD activity at 50 microg x g(-1) TCB recovered towards control level (P>0.05) while a significant increase in SOD activity was observed at 100 and 200 microg x g(-1) TCB compared to control (P<0.05). The experiments also revealed that a significant increase of MDA level in seedlings occurred after 3 and 5 d of 100 and 200 microg x g(-1) TCB treatment (P<0.05 and P<0.01), and there was a positive correlation between TCB concentration and MDA level. All the above results showed that SOD activity and MDA level of broadbean seedlings might be proposed as the biomarkers for short-term TCB contamination in soil. Compared to TCB, the toxicity of 50-1000 microg x g(-1) CB or HCB in soil to broadbean seedlings was not observed after a 3 d exposure.

Root growth inhibition and induction of DNA damage in soybean ( Glycine max) by chlorobenzenes in contaminated soil

The cytotoxic and genotoxic effects of 1,2,4-trichlorobenzene (TCB), chlorobenzene (CB), and hexachlorobenzene (HCB) on root growth and DNA strand breakage damage of soybean nuclei in the test soil were studied using the comet assay. Results indicated that the root growth was significantly inhibited, and DNA strand breaks and the comet tail in the root tip nuclei were both induced after 48 h exposure with TCB concentrations of 50, 100, 200, 300 μg g −1 in the soil. DNA strand breakage was more sensitive to the TCB than the root growth. There was a significant dose–response relationship between the TCB exposure and DNA strand breakage in the soybean nuclei. Thus it is possible for DNA strand breakage to be used as a biomarker of soybean exposed to TCB contamination. Significant cytotoxic threshold concentration of the TCB exposure on the root growth inhibition was determined as 61 μg g −1 in the soil. The toxicity of 100–1000 μg g −1 CB and HCB to the soybean seedlings in the soil were not observed after 48 h or longer exposure.

Polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and non-ortho, mono-ortho chlorine substituted biphenyls in Japanese human liver and adipose tissue.

We measured PCDDs/DFs levels in Japanese human livers and adipose tissues in 1999, and TEQ were calculated with WHO TEF. The mean total levels of PCDDs/DFs in livers and adipose tissues were 57 pg TEQ/g on a lipid basis and 49 pg TEQ/g on a lipid basis, respectively. 1,2,3,6,7,8-HxCDD, 1,2,3,4,6,7,8-HpCDD, OCDD, 2,3,4,7,8-PeCDF, 1,2,3,4,7,8-HxCDF, 1,2,3,6,7,8-HxCDF, 2,3,4,6,7,8-HxCDF, 1,2,3,7,8,9-HxCDF and 1,2,3,4,6,7,8-HpCDF concentrations in livers considerably differed from those in 1989 (p < 0.05). The mean non-ortho-chlorine substituted biphenyls levels showed 20 pg TEQ/g on a lipid basis and 17 pg TEQ/g on a lipid basis in livers and adipose tissues, respectively. In livers, the mean of 3,3',4,4'-TCB concentrations was 131 pg/g on a lipid basis, and 7.7-fold higher than that in 1989. The mean total mono-ortho-chlorine substituted biphenyls level was 13.0 pg TEQ/g on a lipid basis in livers and 21.6 pg TEQ/g on a lipid basis in adipose tissues. 3,3',4,4',5-PeCB and 3,3',4,4',5,5'-HxCB levels decreased in adipose tissues, and 3,3',4,4',5-PeCB level only decreased in livers. PCDDs, PCDFs, and mono- and non-ortho-chlorine substituted biphenyls levels may have decreased in livers and adipose tissues because of a governmental policy on dioxins discharge for the decade. Then, we estimated the correlations of PCDDs, PCDFs and the related compound levels between livers and adipose tissues. The correlative PCDDs congeners may have had a similar behavior to that between liver and adipose tissue. On the contrary, most PCDFs isomers may have different behavior between liver and adipose tissue, while 2',3,4,4',5-PeCB (IUPAC No. 123) may also have a different behavior between liver and adipose tissue.

The effects of the co-existing compounds on the decomposition of micropollutants using the ozone/hydrogen peroxide process

The effect of co-existing compounds on the decompositions of three target compounds (i.e., 1,2,4-trichlorobenzene (TCB), 1,4-dioxane, and 17β-estradiol) using the ozone/hydrogen peroxide (O3/H2O2) process was investigated. Their reactivities toward HO• are assumed to be of the order of 109 /M · s. The decomposition rate of TCB was much higher during the O3/H2O2 process than during ozonation in the presence of bicarbonate ion, an inhibitor of radical chain reactions. 17β-Estradiol, a highly reactive target compound toward ozone, was decomposed at lower ozone dose than TCB and 1,4-dioxane, lowly reactive target compounds toward ozone, in the presence of humic acid. The reactivities of the co-existing compounds toward HO• were significantly related to the treatment efficiency of TCB when their concentrations as TOC were similar. The effect of humic acid, fulvic acid, and glucose, target compounds highly reactive toward HO•, on the decomposition of TCB was similar regardless of co-existing compounds. On the other hand, significantly lower effect of acetate and oxalate ions, target compounds lowly reactive toward HO•, on the decomposition of TCB was observed. Ozone dose required for the decomposition of TCB was inversely proportional to TCB concentration when HO• generated was greatly scavengedby co-existing compounds. On the other hand, ozone dose required for the decomposition of TCB was less affected by TCB concentration when HO• generated was used effectively for the decomposition of TCB.

Multiple Roles of Polyhalogenated Biphenyls in Causing Increases in Cytochrome P450 and Uroporphyrin Accumulation in Cultured Hepatocytes

Uroporphyrin (URO) accumulation occurs in chick embryo hepatocytes treated with a number of polyhalogenated aromatic hydrocarbons (PHAHs) that are known inducers of cytochrome P4501As (CYP1A). Previous dose response studies had shown that URO accumulation does not begin until CYP1A, as indicated by ethoxyresorufin O-deethylase (EROD) activity, is maximally induced. The reason why the concentrations of PHAHs required for URO accumulation were higher than those required to induce EROD had not been explained. PHAHs, such as 3,3′,4,4′-tetrachlorobiphenyl (PCB77, IUPAC nomenclature, TCB) stimulate uroporphyrinogen (UROGEN) oxidation by microsomes from 3-methylcholanthrene (MC)-treated chick embryos. Here we used a new protocol to investigate whether the requirement for more TCB to stimulate in vitromicrosomal UROGEN oxidation extended to TCB-induced URO accumulation in intact cultured hepatocytes. Cultures were treated with increasing concentrations of TCB or other PHAHs to induce CYP1As, then with cycloheximide (CX) to prevent further P450 synthesis. The CX treatment was shown to block any further increases in CYP1A as determined by immunoblots. 5-Aminolevulinic acid and a high concentration of TCB (“postinduction TCB”) were then added to stimulate intracellular UROGEN oxidation. Using the protocol with postinduction TCB, the inducing concentrations of TCB which caused URO to begin to accumulate were now much lower than in the absence of postinduction TCB. Increases in CYP1A proteins, measured immunochemically, were detected at about the same inducing TCB concentrations that began to increase URO accumulation. The new protocol, with postinduction TCB, using URO accumulation as the end point, greatly increased the sensitivity of the culture system for detection of PHAHs with EC50s (n m) for 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD), TCB, 3,3′,4,4′,5,5′-hexachlorobiphenyl, MC, and hexachlorobenzene being about 0.003, 0.11, 0.75, 3.5, and 30, respectively. As little as 2–4 fmol TCDD per culture dish caused detectible increases in URO accumulation. We conclude that URO accumulation in chick hepatocyte cultures is limited not only by the induction of CYP1A, but also by the stimulation of intracellular UROGEN oxidation.

Bioconcentration of 5,5?,6 -trichlorobiphenyl and pentachlorophenol in the midge, Chironomus riparius, as measured by a pharmacokinetic model

A two compartment pharmacokinetic model was developed which describes the uptake and elimination of 5,5′,6-trichlorobiphenyl (TCB) and pentachlorophenol (PCP) in the midge, Chironomus riparius. C. riparius were exposed to nominal TCB (2 μg L−1) and PCP (9 μg L−1) concentrations during a 16 h static uptake phase. Depuration was determined over approximately 45 h using a flowthrough system without feeding. The uptake clearance (P) was 330±61 ml g−1 midge h−1 for TCB and 55±4 ml g−1 midge h−1 for PCP, while measured bioconcentration factors (BCF) were 35,900 and 458 for TCB and PCP, respectively. Overall, the clearance-volume-based pharmacokinetic model predicted BCF values that were consistent with published values as well as with BCF values obtained from the octanol-water partition coefficient (KOW).

ChemInform Abstract: STUDIES OF MOLECULAR REORIENTATION, TRANSLATION, AND VIBRATIONAL RELAXATION OF LIQUID 1,2,4‐TRICHLOROBENZENE BY DEPOLARIZED RAYLEIGH AND RAMAN SPECTROSCOPY

The depolarized Rayleigh and Raman scattering spectra of 1,2,4‐trichlorobenzene (TCB) in CCl4 have been measured as a function of concentration at several tempertures in high resolution. The depolarized Rayleigh spectra were obtained using a Fabry–Perot interferometer and the high resolution Raman spectra were obtained using a tandem spectrometer consisting of a Fabry–Perot interferometer and a double grating monochromator. The central dip due to shear wave coupling to reorientational motion is observed in the depolarized Rayleigh spectrum. The Rayleigh relaxation times τRay obtained for TCB depend on the TCB concentration. The concentration dependence of the Rayleigh times indicates the importance of orientational pair correlation in TCB. The single particle orientational relaxation times τs were obtained by extrapolating from τRay data to infinite dilution. The activation energy for molecular reorientation which is found to be affected by pair correlation decreases with decreasing concentration, with mo...

Studies of molecular reorientation, translation, and vibrational relaxation of liquid 1,2,4-trichlorobenzene by depolarized Rayleigh and Raman spectroscopy

The depolarized Rayleigh and Raman scattering spectra of 1,2,4-trichlorobenzene (TCB) in CCl4 have been measured as a function of concentration at several tempertures in high resolution. The depolarized Rayleigh spectra were obtained using a Fabry–Perot interferometer and the high resolution Raman spectra were obtained using a tandem spectrometer consisting of a Fabry–Perot interferometer and a double grating monochromator. The central dip due to shear wave coupling to reorientational motion is observed in the depolarized Rayleigh spectrum. The Rayleigh relaxation times τRay obtained for TCB depend on the TCB concentration. The concentration dependence of the Rayleigh times indicates the importance of orientational pair correlation in TCB. The single particle orientational relaxation times τs were obtained by extrapolating from τRay data to infinite dilution. The activation energy for molecular reorientation which is found to be affected by pair correlation decreases with decreasing concentration, with most rapid decrease occuring at low concentration. The spectral linewidth of the 677 cm−1 band shows a weak concentration dependence, thus suggesting that the vibrational effect of the 677 cm−1 band in neat TCB can be interpreted in terms of single particle dynamics. Further studies show that the vibrational linewidth is due to the intramolecular interaction.