Short Pretreatment Time Research Articles

Photocatalytic degradation of concentrated solutions of 2,4-dichlorophenol using low energy light: Identification of intermediates

This study reports on Fenton and photo-assisted Fenton induced oxidation of 2,4-dichlorophenol (from here on 2,4-DCP). The pre-treatment of concentrated aqueous solutions of 2,4-DCP (453mgl−1) up to bio-compatibility is shown to be possible using low energy 36W black fluorescent mercury light. The degradation process of 2,4-DCP was observed to occur within minutes. Catalytic amounts of Fe3+-ion (10mg) were only necessary to obtain acceptable degradation kinetics. Degradation of the 2,4-DCP was not observed in the dark. The total organic carbon (TOC), the adsorbable organic halogen compounds (AOX) and the amount of free chloride (Cl−) were followed in time during 2,4-DCP oxidation under light irradiation. The rate of disappearance of 2,4-DCP and that of Cl−-ion formation were not similar. This was ascribed to the formation of aliphatic and aromatic chlorinated long-lived intermediates. The latter intermediates were identified by liquid–liquid extraction, solid–liquid extraction and coupled GC/MS analysis. Based on the experimental results obtained, a mechanism for the radical intervention is suggested for the abatement of 2,4-DCP. A relatively short pre-treatment time (54min) was necessary to reduce by 97% the toxicity (ecotoxicity) of a concentrated solution of 2,4-DCP under low energy light irradiation in the photo-reactor.

Molten Carbonate Fuel Cell (MCFC) Reactor for Selective Conversion of Methane with Li-Ni/Al2O3 and La2O3 Anode Catalysts.

The molten carbonate fuel cell (MCFC) system was applied to a reactor for the selective conversion of methane to produce synthesis gas and C2 compounds (ethane and ethylene). The cell type MCFC reactor was designed for improved stability and shorter pretreatment time. The doctor blade method was effective for the construction of the cell.The design of the anode catalyst is essential for this reaction. Two types of catalysts were prepared for the MCFC reactor. Li-Ni/Al2O3 catalyst was used for producing synthesis gas and La2O3 catalyst for C2 compounds. These anode materials selectively produced the required chemicals with corresponding electric power.

Lime pretreatment of crop residues bagasse and wheat straw

Lime (calcium hydroxide) was used as a pretreatment agent to enhance the enzymatic digestibility of two common crop residues: bagasse and wheat straw. A systematic study of pretreatment conditions suggested that for short pretreatment times (1–3 h), high temperatures (85-135°C) were required to achieve high sugar yields, whereas for long pretreatment times (e.g., 24 h), low temperatures (50–65°C) were effective. The recommended lime loading is 0.1 g Ca(OH)2/g dry biomass. Water loading had little effect on the digestibility. Under the recommended conditions, the 3-d reducing sugar yield of the pretreated bagasse increased from 153 to 659 mg Eq glucose/g dry biomass, and that of the pretreated wheat straw increased from 65 to 650 mg Eq glucose/g dry biomass. A material balance study on bagasse showed that the biomass yield after lime pretreatment is 93.6%. No glucan or xylan was removed from bagasse by the pretreatment, whereas 14% of lignin became solubilized. A lime recovery study showed that 86% of added calcium was removed from the pretreated bagasse by ten washings and could be recovered by carbonating the wash water with CO2 at pH 9.5.

A Test of the Predictive Validity of Animal Models of Schizophrenia Based on Phencyclidine and D-Amphetamine

Antipsychotic drugs can inhibit the effects of phencyclidine (PCP) and d-amphetamine (AMPH) in many rodent tests, but the effects are usually seen at doses that also affect vehicle-treated control rats, suggesting that the inhibition may be nonspecific. This study will attempt to test the predictive validity of these models based on the clinical observations that antipsychotics are not fully effective until after 2–3 weeks of administration in patients and that patients do not relapse immediately following abrupt withdrawal of medication. Haloperidol and clozapine were tested in rats after daily administration for 3 and 21 days in combination with vehicle or PCP (2.0 mg/kg) in the social interaction test, and with vehicle or AMPH (0.5 mg/kg) in standard activity cages. To separate acute from more long-lasting effects on the central nervous system (CNS) haloperidol and clozapine were tested with a short (45 or 30 min depending upon test) and a long (22–24 h) pretreatment time. The results demonstrated that haloperidol and clozapine following both 3 and 21 days of administration at the short pretreatment time inhibited the activity of vehicle-, PCP-, and AMPH-treated rats, whereas neither drug had consistent effects in any group at the long pre-treatment time. The data suggest that antipsychotics only inhibit PCP- and AMPH-induced behaviors in rodents by an acute drug-drug interaction, whereas any long-term effects of antipsychotic drug administration on the CNS cannot be revealed by PCP and AMPH in rodents.

Effect of Glow Discharge-Polymer Treatments on the Shrinkage Behavior and Physical Properties of Wool Fabric

The application of glow discharge plasma to the surface of wool fabric is known to increase fiber hydrophilicity and confer a partial shrink resist effect during washing. In this work, four different polymer systems, Basolan SW, Basolan MW, Polymer G, and Polymer PL, are applied onto plasma treated wool fabric to enhance the degree of shrink resistance. The level of shrink resistance varies significantly with plasma-polymer treatments, depending on the kind of polymer system applied, with Polymers PL and G conferring excellent shrink resistance even for very short plasma pretreatment times of 2 minutes. The extent of weight loss during washing is also minimized for all plasma-polymer applications relative to polymer-only or chlorinated-polymer treated wool. Fabric tear strength and handle are adversely affected by plasma treatment, but these properties are favorably restored on polymer application. Wrinkle recovery decreases with plasma treatment time, and this property is not improved with polymer application.

Discriminated conditioned taste aversion for studying multi-element stimulus control

The effects of morphine pre-treatment interval on the stimulus control exerted by a multi-element stimulus consisting of morphine (5.6mg/kg), saccharin (0.2%, w/v), and a ball-bearing drinking nozzle in a discriminated taste aversion procedure were examined. In this discriminated aversion procedure, rats received injections of LiCI following presentation of this multielement stimulus, and injections of saline following the saline, water, and non-ball-bearing nozzle composite stimulus. These paired rats were compared to unpaired rats that received saline injections rather than LiCI injections following presentation of the multi-element stimulus. Morphine pre-treatment times of 5, 10, and 20min were examined in groups of 12 paired and 6 unpaired rats. The discrimination was rapidly learned under all three pre-treatment intervals. In subsequent testing with each individual stimulus element and combinations of two stimulus elements, stimulus control was clearly exerted by both morphine and saccharin. Paired rats drank less saccharin than unpaired rats, and less saccharin than water. Similarly, paired rats drank less fluid following morphine administration than following saline administration, and less fluid than unpaired rats following morphine administration. Control by the nozzle type was also apparent in significant interactions between the nozzle and morphine or saccharin and pairing with LiCI. In general, pre-treatment time did not influence the stimulus control that developed. However, at the two shorter pre-treatment times there was some indication that a conditioned taste aversion to morphine was developing in the unpaired rats. These experiments indicate that such discriminated taste aversion procedures may be viable methods for studying the contextual control of how drugs function as discriminative stimuli, and that longer drug pre-treatment times may be desirable in such procedures.

Activation of the neutrophil bactericidal activity for nontypable Haemophilus influenzae by tumor necrosis factor and lymphotoxin.

Previous studies have suggested that, in vivo, activated T lymphocytes and neutrophils are important in immunity to nontypable Haemophilus influenzae. We now extend this work by showing that neutrophils pretreated with products of activated T lymphocytes or activated macrophages show significantly enhanced killing of nontypable H. influenzae. Lymphotoxin, a product of activated T lymphocytes, significantly enhanced the neutrophil-mediated killing of nontypable H. influenzae, and tumor necrosis factor, produced by activated T lymphocytes as well as macrophages stimulated by activated T lymphocytes, also significantly increased the bactericidal activity of neutrophils. These cytokine-induced effects were seen with short pretreatment times of neutrophils and were maximal by 30 min. The killing of H. influenzae by neutrophils required the presence of heat-labile opsonins. In the absence of these opsonins, both tumor necrosis factor and lymphotoxin were unable to promote the killing of the bacteria by neutrophils. Furthermore, the results showed that tumor necrosis factor-primed neutrophils displayed significantly increased expression of CR3 and CR4 that was associated with increased phagocytosis of complement-opsonized nontypable H. influenzae. These cytokines may play an important role in immunity toward nontypable H. influenzae by stimulating neutrophil bactericidal activity.

Liver accumulation of 2,3,7,8-tetrachloro-[ 3H]dibenzofuran in mice: modulation by treatments with polychlorinated biphenyls

The distribution of 2,3,7,8-tetrachloro-[ 3H]dibenzofuran ([ 3H]TCDF; 40 μg/kg) resembled that earlier reported for 2,3,7,8-tetrachlorodibenzo- p-dioxin, with a strong accumulation in the liver and a selective uptake in the nasal olfactory mucosa of adult and fetal mice. Pretreatments with a series of selected congeners of polychlorinated biphenyls (PCBs), i.e.. I (IUPAC)-77, I-105, I-118, I-126, I-153, I-156, I-169, and a commercial preparation, Aroclor 1254 (25–100 mg/kg body wt. i.p.), were found to modulate the hepatic uptake of [ 3H]TCDF (24 h post- 3H-injection). At a short pretreatment time (4 h), non- ortho-chlorinated congeners decreased the uptake of [ 3H]TCDF equivalents in the liver (e.g., I-126 = 3,3′,4,4′,5-pentachlorobiphenyl: 34% of control), while several mono- and di- ortho PCB congeners and Aroclor 1254 increased the hepatic uptake of [ 3H]TCDF (e.g., I-156 = 2,3,3′,4,4′,5-hexachlorobiphenyl: 183% of control). At a longer pretreatment time (48 h), both a non- ortho (I-169 = 3,3′,4,4′,5,5′-hexachlorobiphenyl) and mono- ortho PCB congener(s) (e.g. I-156) markedly increased the hepatic 3H-uptake (190%), a probable effect of an induction of hepatic binding sites for TCDF. Ethoxyresorufin- O-deethylase activities, regarded to mirror the metabolic activity of cytochrome P-450 IA1 (CYP IA1), were strongly and time-dependently induced after I-169, but not after I-156, pretreatment (25 mg/kg). The initial liver concentrations of the two PCB congeners were similar and increased for I-169 but not for I-156 at later time points. In conclusion, the results show a selective uptake of [ 3H]TCDF in the mouse liver and nasal olfactory mucosa of both dam and fetus. The uptake of [ 3H]TCDF in the liver is influenced both by dose and pre-exposure with PCBs. The presence of a PCB-sensitive, but CYP IA1-independent, hepatic binding site for TCDF is suggested. Consequently, pharmacokinetic interactions with PCBs complicate the toxicity assessment of TCDF in complex mixtures.

Adhesion Promotion in Rayon/Nylon Skin/Core Bigeneric Fibers

Rayon/nylon skin/core bigeneric fibers have been developed to combine mechanical properties ofsynthetic core material with moisture and comfort properties of cellulosic skin. Fibers are produced in a fiber coating operation where oriented nylon fiber is coated with viscose rayon solution in a fiber coating die. For fibers produced in earlier studies, adhesion between skin and core was not sufficient, and the skin debonded during subsequent processing. In this study, fumaric acid (FA) was used as an adhesion promoter in rayon coated fibers. Results of a severe abrasion test show that FA is an effective coupling agent with adhesion dependent on application conditions. There was significant interaction between FA concentration and time of FA pretreatment; high concentrations at shorter pretreatment times and low concentrations at longer times gave best adhesion. Results of the adhesion test were confirmed with electron microscopy.

The effects of p-chloromercuriphenylsulfonic acid on Trypanosoma cruzi infection of mammalian host cells in vitro.

Treatment of Trypanosoma cruzi blood trypomastigotes with p-chloromercuriphenylsulfonic acid (PCMS) increased the association of the parasite with either mouse resident peritoneal macrophages or rat heart myoblasts in vitro. The effect was evidenced by elevation of both the percentage of host cells with parasites and the number of flagellates per 100 cells. The effect of PCMS appeared to be largely on the process of parasite penetration rather than surface binding as it was seen at 37 degrees C but not at 4 degrees C. A short pretreatment time, 5 min, was sufficient to elicit the enhancement, suggesting that the primary effect of PCMS might be at the parasite's cell surface. The PCMS effect was reversible as the parasite returned to normal levels of association with the host cells in less than 4 h after removal of excess PCMS. That sulfhydryl groups were involved in the PCMS effect was indicated by the abilities of excess cysteine and glutathione to block it. These results suggest a role for free sulfhydryl groups on the parasite surface in the process of host cell invasion.

The effects of dipyridamole on the guinea-pig ileal longitudinal muscle-myenteric plexus preparation.

1 The longitudinal muscle-myenteric plexus strip prepared from guinea-pig ileum has been used to study the actions of dipyridamole and its interactions with adenine derivatives. 2 Dipyridamole augmented the inhibitory effects of adenine derivatives on the twitch response induced by 0.1 Hz field stimulation of the preparation. This synergistic effect was apparent with relatively low concentrations of dipyridamole (10 to 100 nM) and after short pretreatment times (1 to 2 min) that did not inhibit the twitch response on their own. Appropriate studies suggested the dipyridamole-adenosine synergism followed a pattern of facilitative agonist competition. 3 Dipyridamole did not inhibit either uptake of [3H]-adenosine by the preparation or adenosine deaminase activity under the same conditions that it exhibited synergism with adenosine. 4 Higher concentrations of dipyridamole inhibited the twitch response, mainly by decreasing acetylcholine release but partly by a direct action on smooth muscle. The direct action of dipyridamole on muscle was not synergistic with adenosine. 5 Fluorescence microscopy showed preferential binding of dipyridamole to the myenteric plexus.

New Method of Studying Corrosion Inhibition of Iron with Sodium Silicate

A rapid laboratory method is presented for testing the effectiveness of sodium silicate as an anodic inhibitor. Passivity curves taken on polished steel electrodes, pre ‐treated for 24, or better, 48 hr in aerated solutions of sodium silicate (3–500 ppm silica) and compared with sodium hydroxide solutions of the same pH, indicate that silica, and not merely an increase in pH, caused inhibition. No corrosion products were observed in the short pretreatment time for electrodes treated with 15 and more ppm silica, whereas all sodium hydroxide treáted electrodes corroded. The method can be made the basis of a practical test by pretreating the electrodes, in the actual environment being treated, with sodium silicate. The procedure also appears to be applicable in the testing of other anodic inhibitors.