Initial Exposure Time Research Articles

Timing of Initial Exposure to Cereal Grains and the Risk of Wheat Allergy

Early exposure to solid foods in infancy has been associated with the development of allergy. The aim of this study was to examine the association between cereal-grain exposures (wheat, barley, rye, oats) in the infant diet and development of wheat allergy. A total of 1612 children were enrolled at birth and followed to the mean age of 4.7 years. Questionnaire data and dietary exposures were obtained at 3, 6, 9, 15, and 24 months and annually thereafter. The main outcome measure was parent report of wheat allergy. Children with celiac disease autoimmunity detected by tissue transglutaminase autoantibodies were excluded. Wheat-specific immunoglobulin E levels on children reported to have wheat allergy were obtained. Sixteen children (1%) reported wheat allergy. Children who were first exposed to cereals after 6 months of age had an increased risk of wheat allergy compared with children first exposed to cereals before 6 months of age (after controlling for confounders including a family history of allergic disorders and history of food allergy before 6 months of age). All 4 children with detectable wheat-specific immunoglobulin E were first exposed to cereal grains after 6 months. A first-degree relative with asthma, eczema, or hives was also independently associated with an increased risk of wheat-allergy development. Delaying initial exposure to cereal grains until after 6 months may increase the risk of developing wheat allergy. These results do not support delaying introduction of cereal grains for the protection of food allergy.

Timing of Initial Exposure to Cereal Grains and the Risk of Wheat Allergy

RATIONALE: Early exposure to solid foods in infancy has been associated with the development of allergy. The aim of this study was to examine the association between cereal grain exposures (wheat, barley, rye, oats) in the infant diet and development of wheat allergy.

Influence of the estrous cycle on tolerance development to LPS-induced sickness behaviors in rats

The relations between the estrous cycle, inflammatory responses and the development of tolerance to endotoxin were examined. Female Long-Evans rats were injected intraperitoneally with lipopolysaccharide (LPS; 200 microg/kg) or saline vehicle at 08:00h on either diestrus (D) or proestrus (P). Ninety-five minutes after injection locomotor activity was assessed in an automated non-novel open-field for 20 min. To assess tolerance development to LPS, rats were re-injected at the next identical stage (i.e. 4 days later; groups: DD, PP) or at the alternate stage (i.e. 6 days later; groups: DP, PD) of the estrous cycle and locomotor activity was again assessed. On Test Day 1 all groups injected with LPS exhibited similar significant activity decrements, regardless of the stage of the estrous cycle. However, on Test Day 2 rats which received both injections of LPS during proestrus (PP) showed no signs of tolerance development, whereas rats in all other groups were tolerant to LPS. In a follow up study, the time between injections was extended to 8 days. Still the animals injected both times at proestrus showed no signs of tolerance to LPS after the second injection. Thus, the stages of the estrous cycle both at the time of initial exposure and of re-exposure appear critical in the formation of behavioral tolerance to LPS in rats.

Determination of the period for establishment of a liver network echogenic pattern in Schistosoma japonicum infection

Schistosomiasis is caused by infection with Schistosoma haematobium, S. mansoni, S. japonicum, or S. mekongi. S. japonicum infection results in liver cirrhosis at the final stage. A “network” (NW) echogenic pattern on hepatic ultrasonography appears to be specific to S. japonicum infection. The principal aim of the present study was to determine the exact year(s) or even month(s) required for the establishment of the liver NW echogenic pattern from the initial infection in young patients with schistosomiasis japonica since there are few data on this important point. We conducted yearly ultrasonographic, serologic, coprologic, and physical examinations of schistosomiasis patients in the Philippines from 1996 up to the present. During that period, the total number of patients examined was approximately 2,000, among whom we selected 2 patients for determination of the duration required for NW establishment, when they were 10 years old. Although the exact time of initial exposure to schistosomes cannot be determined, the duration for the establishment of NW was definitively confirmed in patient no. 1 to be between 19–24 months based on the results of serologic and coprologic examinations. For patient no. 2, the circumstantial evidence suggested that the establishment of a NW might require 5 to 6 years at maximum. To the best of our knowledge, this is the first evidence-based report on the determination of the period required for the establishment of a liver NW echogenic pattern in S. japonicum infection in the Philippines.

Static magnetic field effects on human subjects related to magnetic resonance imaging systems

Goal: This paper reviews recent studies evaluating human subjects for physiologic or neuro-cognitive function adverse effects resulting from exposure to static magnetic fields of magnetic resonance imaging systems. Materials and Methods: The results of three studies are summarized. Two studies evaluated exposure to a maximum of 8 Tesla (T). The first series studied 25 normal human subjects’ sequential vital signs (heart rate, blood pressure, blood oxygenation, core temperature, ECG, respiratory rate) measured at different magnetic field strengths to a maximum of 8 T. A second series of 25 subjects were studied at 0.05 and 8 T (out and in the bore of the magnet), performing 12 different standardized neuro-psychological tests and auditory–motor reaction times. The subjects’ comments were recorded immediately following the study and after a three-month interval. The third study contained 17 subjects, placed near the bore of a 1.5 T magnet, and it used six different cognitive, cognitive–motor, or sensory tests. Results: There were no clinically significant changes in the subjects’ physiologic measurements at 8 T. There was a slight increase in the systolic blood pressure with increasing magnetic field strength. There did not appear to be any adverse effect on the cognitive performance of the subjects at 8 T. A few subjects commented at the time of initial exposure on dizziness, metallic taste in the mouth, or discomfort related to the measurement instruments or the head coil. There were no adverse comments at 3 months. The 1.5 T study had two of the four neuro-behavioral domains exhibiting adverse effects (sensory and cognitive–motor). Conclusions: These studies did not demonstrate any clinically relevant adverse effects on neuro-cognitive testing or vital sign changes. One short-term memory, one sensory, and one cognitive–motor test demonstrated adverse effects, but the significance is not clear.

Vitamin A Deficiency Increases the In Vivo Development of IL-10–Positive Th2 Cells and Decreases Development of Th1 Cells in Mice

Vitamin A deficiency impairs both T helper type 1 (Th1)- and type 2 (Th2)-mediated immune responses, although Th2 responses seem to be principally affected. Multiple mechanisms are involved in this immune suppression, but the hypothesis that deficiency affects development of Th1/Th2 memory cell phenotype has not been tested directly in vivo. To do so, lymphocytes from DO11.10 T cell receptor (TCR)-transgenic mice were transferred to vitamin A-deficient or control BALB/c recipients. Recipients were then immunized with the cognate peptide antigen for the TCR-transgenic DO11.10 T cells (OVA(323-339)). After 2-5 wk, the transferred OVA(323-339)-specific T cells were identified from draining lymph nodes with the TCR-clonotypic antibody KJ1-26, and their Th1/Th2 phenotype was characterized by intracellular cytokine staining after in vitro stimulation with phorbol myristate acetate and ionomycin. The percentage of CD4(+)KJ1-26(+) cells positive for IL-10 was 100% greater in vitamin A-deficient mice (3.49 +/- 0.41%; mean +/- SE) than in control mice (1.74 +/- 0.37%). IL-4 did not differ between groups. In addition, the percentages of CD4(+)KJ1-26(+) cells from vitamin A-deficient mice that were positive for interferon (IFN)-gamma (8.8 +/- 0.73%) and interleukin (IL)-2 (39.5 +/- 3.1%) were both lower than the percentages in control mice (11.4 +/- 0.67 and 47.0 +/- 2.8%, respectively). Thus vitamin A deficiency, at the time of initial antigen exposure, enhances the development of IL-10-producing Th2 or T regulatory cells and diminishes the development of Th1 memory cells.

Studies of water transport behavior and impedance models of epoxy-coated metals in NaCl solution by EIS

Using electrochemical impedance spectroscopy (EIS) technique, the analyses of impedance models and the water uptake processes of epoxy-coated mild steels and LY12 aluminum alloys immersed in 3.5% (weight fraction) NaCl solution were studied. The fitting results using suitable electrical equivalent circuits (EEC) suggested that there were four kinds of impedance models in the course of immersion. In the initial period of immersion, an EEC containing the coating capacitance and the coating resistance was used to fit the EIS data. Along with the immersion time, the number of time-constant of impedance spectra for metal/coating systems increased, indicating that corrosion reaction took place. After a certain time's attacking of metal substrates, the diffusion process towards solution of corrosion products forming at the metal/coating interface might be restrained due to the presence of coating barrier, resulting in the appearance of diffusion elements. This diffusion did not act as an ideal Warburg behavior, leading to a deviation of dispersive number, n, from 0.5. After longer immersion times, the Cl − ions reached the surface of metal through the coating and participated in chemical reactions with corrosion products to form salt film on aluminum alloy surface. The formation of chloride ion-incorporation salt film resulted in the change of impedance spectrum characteristics. The studies revealed that the water transport in epoxy varnish coatings followed the Fickian diffusion law during the initial time of exposure to the testing solution. After immersion for a certain time, the water uptake reached saturation and the coating capacitance tended to a relatively steady value. According to the variation of coating capacitance with time, the water diffusion coefficient was deduced. The experimental results indicated that the water diffusion coefficients in epoxy coatings were slightly dependent on coating thickness and were to some extent influenced by substrate type. The similar surface chemical structures of epoxy coatings on different metals were found from the Fourier transform infrared spectroscopy (FT-IR)–attenuated total reflection (ATR) measurements. The glass transition temperature ( T g) of epoxy coatings prepared on different metal substrates before and after immersion was measured by using differential scanning calorimetry (DSC). Lower diffusion rate of water in Al alloy based epoxy films than that in steel based ones was interpreted by the higher absolute value and smaller decrease of T g of organic coatings painted on the former substrate.

Management of Community-Acquired Pneumonia

Management of Community-Acquired Pneumonia

Studies of impedance models and water transport behaviors of polypropylene coated metals in NaCl solution

Using electrochemical impedance spectroscopy (EIS) technique, the water uptake process and the evolution of impedance models of polypropylene coated mild steels and LY12 Al alloys immersed in 3.5% (weight fraction) NaCl solution were studied. The equivalent electrical circuit (EEC) fitting results suggested that there was one single semi-circle in the impedance spectra of immersed samples in the initial period of immersion, which was corresponded to one time constant. Along with the immersion time, the number of time constant in EEC for metal/coating electrode system increased. The diffusion process towards solution of corrosion products forming on the metal/coating interface might be restrained due to the influence of coating barrier, resulting in the initiation of diffusion component in EEC. This diffusion did not act as a Warburg behavior, leading to a deviation of dispersive number, n, from 0.5. The studies revealed that the water transport in polypropylene clear varnish followed the Fickian diffusion during the initial time of exposure to the solution. After a certain time of immersion, the water uptake reached a saturation value. According to the variation of coating capacitance with time, the water diffusion coefficient was deduced. The experimental results indicated that the water diffusion coefficients in polypropylene coatings were independent of substrate materials used and coating thickness. Relative dielectric constant of dry coatings ( ε d) and water volume fraction of the coatings at saturation ( φ ∞) were also calculated. The similar results were found in time dependence of coating capacitance calculated from the impedance imaginary component at a fixed high frequency and that obtained from the fitting result by EEC, which indicated that the coating capacitance from the impedance imaginary component was reliable to evaluate barrier performance of coatings against water.

Timing of initial cereal exposure in infancy and risk of islet autoimmunity.

Dietary exposures in infancy have been implicated, albeit inconsistently, in the etiology of type 1 diabetes mellitus (DM). To examine the association between cereal exposures in the infant diet and appearance of islet autoimmunity (IA). Birth cohort study conducted from 1994 to 2002 with a mean follow-up of 4 years. Newborn screening for HLA was done at St Joseph's Hospital in Denver, Colo. First-degree relatives of type 1 DM individuals were recruited from the Denver metropolitan area. We enrolled 1183 children at increased type 1 DM risk, defined as either HLA genotype or having a first-degree relative with type 1 DM, at birth and followed them prospectively. We obtained exposure and outcome measures for 76% of enrolled children. Participants had variable lengths of follow-up (9 months to 9 years). Blood draws for the detection of insulin autoantibody, glutamic acid decarboxylase autoantibody, or IA-2 autoantibody were performed at 9, 15, and 24 months and annually thereafter. Children with IA (n = 34) were defined as those testing positive for at least 1 of the autoantibodies on 2 or more consecutive visits and who tested positive or had diabetes on their most recent visit. Children initially exposed to cereals between ages 0 and 3 months (hazard ratio [HR], 4.32; 95% confidence interval [CI], 2.0-9.35) and those who were exposed at 7 months or older (HR, 5.36; 95% CI, 2.08-13.8) had increased hazard of IA compared with those who were exposed during the fourth through sixth month, after adjustment for HLA genotype, family history of type 1 DM, ethnicity, and maternal age. In children who were positive for the HLA-DRB1*03/04,DQB8 genotype, adjusted HRs were 5.55 (95% CI, 1.92-16.03) and 12.53 (95% CI, 3.19-49.23) for initial cereal exposure between ages 0 to 3 months and at 7 months or older, respectively. There may be a window of exposure to cereals in infancy outside which initial exposure increases IA risk in susceptible children.

Exposure to Maternal Depression and Marital Conflict: Gender Differences in Children's Later Mental Health Symptoms

To investigate effects of the timing of initial exposure to maternal depression and marital conflict on kindergarten children's mental health symptoms. For 406 families (of 570 originally recruited), mothers reported on major depression and marital conflict on multiple occasions in the child's infancy and toddler/preschool periods. Mothers and teachers completed the MacArthur Health and Behavior Questionnaire when children were in kindergarten. Children evidenced co-occurring internalizing and externalizing symptoms, although the mix was more toward internalizing for girls and externalizing for boys. Symptoms were more severe among children exposed to either adversity, and these effects were additive. Boys exposed to maternal depression in infancy had a preponderance of internalizing behaviors, but if subsequently exposed to marital conflict, the mix toward externalizing behaviors increased to match levels of clinic-referred children. For girls, the preponderance of internalizing symptoms increased to match levels of clinic-referred children when initial exposure to marital conflict occurred in the toddler/preschool period. It is important to consider both adversities across developmental periods, to distinguish the symptom severity from directionality, and to consider child gender. Prevention and intervention efforts that consider these findings are warranted.

Chronic exposure of nicotine modulates the expressions of the cerebellar glial glutamate transporters in rats.

Rats were given nicotine (25 ppm) in their drinking water at the start of their mating period in order to study the expressions of glutamate transporter subtypes in cerebellar astrocytes following the chronic exposure of nicotine after mating. After the offspring were delivered, each group was divided into two subgroups. One group, the control group, was given distilled water only and the other group, the experimental group, was given distilled water containing nicotine. The cerebellar astrocytes were prepared from 7 day-old pups at each group. Ten days after the cells were cultured, the expression of the glutamate transporter subtypes (GLAST and GLT-1) was determined using immunochemistry and immunoblotting. During the continuous treatments, the developmental expression patterns of the GLAST and GLT-1 in the cerebellum were also determined from 2, 4 and 8 week-old rats. The expression levels of GLAST in cultured astrocytes of both the pre- or post-natally exposed groups were higher than those of the control group. However, these expression levels of the continuously exposed group were lower than those of the control group. Compared to those of the control group, the GLT-1 expression levels of all the nicotine-treated groups were higher, particularly in the continuously treated group. According to the results from the immochemistry procedure, the cerebellar GLAST and GLT-1 expression levels of all nicotine-treated groups were lower than those of the control group at each age. However, the immunoblotting procedure showed that the cerebellar GLT-1 expression levels of all the nicotine-treated groups were higher than those of the control group, except for the rats that were continuously exposed for 8 weeks using immunoblotting. These results suggest that the expression of the glial GLAST and GLT-1 are altered differently depending on the initial exposure time and the particular period of nicotine exposure. In addition, nicotine exposure during gestation has persistent effects on glial cells.

Effect of monosodium glutamate on apple leaf consumption by codling moth larvae

AbstractWe have demonstrated that larvae of codling moth, Cydia pomonella (L) can successfully complete their first instar when fed apple leaves instead of fruit. Larvae fed leaves after hatching maximized their feeding intensity (about 320 μg/larva/day) on day 2. Weight gain revealed a stereotypic sigmoid pattern that peaked on day 3. Although the maximum body weight of larvae fed leaves was 70–85% less than for larvae maintained on apples or on artificial diet, 100% of larvae fed leaves molted to the second instar 3–5 days after hatching. Our investigation revealed a diurnal pattern of leaf ingestion, and neonates' feeding intensity decreased significantly during the scotophase. We also demonstrated that monosodium glutamate (MSG) increased feeding on leaves by codling moth larvae. Depending on the duration of the bioassay, and larval age at time of initial exposure, 0.05 mg/ml and 0.1 mg/ml MSG increased apple leaf consumption by 25–60% over leaves alone. The effect of monosodium glutamate was best demonstrated during the first day following hatching. Exposure to MSG also accelerated molting to the second instar. Larvae exposed to MSG initiated consumption of leaf tissue significantly earlier than control neonates. The feeding stimulatory effect of MSG was not observed if exposure to this chemical was delayed until 3–4 h after hatch.The addition of feeding stimulants to pesticides that act via the alimentary tract may reduce the amount of active ingredients needed to maintain the efficacy of these formulations. Here, we postulate that first instar codling moth larvae are potential targets for treatment with pesticide formulations enhanced with monosodium glutamate.

In vitro microbicidal activities of cecropin peptides D2A21 and D4E1 and gel formulations containing 0.1 to 2% D2A21 against Chlamydia trachomatis.

Topically applied microbicides that eradicate pathogens at the time of initial exposure represent a powerful strategy for the prevention of sexually transmitted infections. To aid in the further development of an effective topical microbicide, we assessed the minimum cidal concentration (MCC) of two cecropin peptides, D2A21 and D4E1, and gel formulations containing 0.1 to 2% D2A21 against Chlamydia trachomatis in vitro. The MCC of peptide D2A21 was 5 microM (18.32 microg/ml), and that of peptide D4E1 was 7.5 microM (21.69 microg/ml). The MCC of gel formulations containing 2% D2A21 was 0.2 mM (0.7 mg/ml), and that of gel formulations containing 0.5% D2A21 was 0.2 mM (0.7 mg/ml). There was no significant variation in the results when two different C. trachomatis strains were tested, and the addition of 10% human blood did not significantly alter the MCCs. pH values above and below 7 reduced the activity of the D2A21 peptide alone, but the MCC of the 2% D2A21 gel formulation was only slightly altered at the various pHs tested. Ultrastructural studies indicated that C. trachomatis membranes were disrupted after D2A21 exposure, resulting in leakage of the cytoplasmic contents. These in vitro results suggest that these cecropin peptides may be an effective topical microbicide against C. trachomatis and support the need for further evaluation.

Timing of initial exposure to maternal major depression and children's mental health symptoms in kindergarten

Little is known about the influence on child mental health symptoms of the timing of initial exposure to maternal major depression or whether the timing is associated with 'pure' or co-occurring internalising and externalising symptoms. To address these issues, while also taking account of child gender and family socio-economic status. In a prospective community-based study, 421 kindergarten teachers rated children's symptoms. Previous assessments of maternal major depression indicated whether children were first exposed during infancy, in the toddler/pre-school period, or never. Exposure during infancy was associated with high internalising symptoms, especially when co-occurring with high externalising symptoms. Initial exposure in the toddler/pre-school years increased the risk of 'pure' externalising symptoms among girls. The association of child mental health symptoms with the timing of initial exposure to maternal depression highlights the need for effective prevention and intervention strategies addressed to the developmental issues of each period.

Concordance between the CC Chemokine Receptor 5 Genetic Determinants That Alter Risks of Transmission and Disease Progression in Children Exposed Perinatally to Human Immunodeficiency Virus

If CC chemokine receptor 5 (CCR5)-dependent mechanisms at the time of initial virus exposure are important determinants of virus entry and disease outcome, then the polymorphisms in CCR5 that influence risk of transmission and disease progression should be similar; this hypothesis was tested in a cohort of 649 Argentinean children exposed perinatally to human immunodeficiency virus type 1 (HIV-1). Two lines of evidence support this hypothesis. First, CCR5 haplotype pairs associated with enhanced risk of transmission were the chief predictors of a faster disease course. Second, some of the haplotype pairs associated with altered rates of transmission and disease progression in children were similar to those that we previously found influenced outcome in European American adults. This concordance suggests that CCR5 haplotypes may serve as genetic rheostats that influence events occurring shortly after initial virus exposure, dictating not only virus entry but, by extension, also the extent of early viral replication.

Cost-effectiveness of prophylaxis against Pneumocystis carinii pneumonia in patients with Wegner's granulomatosis undergoing immunosuppressive therapy.

To assess the incremental cost-effectiveness of 3 Pneumocystis carinii pneumonia (PCP) prophylaxis strategies in patients with Wegener's granulomatosis (WG) receiving immunosuppressive therapies: 1) no prophylaxis; 2) trimethoprim/sulfamethoxazole (TMP/SMX) 160 mg/800 mg 3 times a week, which is discontinued if patients experience an adverse drug reaction (ADR); and 3) TMP/SMX 160 mg/800 mg 3 times a week, which is replaced by monthly aerosolized pentamidine (300 mg) if patients experience an ADR. A Markov state-transition model was developed to follow a hypothetical cohort of WG patients over their lifetimes starting from the time of initial exposure to the immunosuppressive therapy. The effect of PCP prophylaxis on life expectancy, quality-adjusted life expectancy, average discounted lifetime cost (ADLC), and incremental cost-effectiveness was estimated based on data obtained from a literature review. Direct medical costs were examined from a societal perspective, and costs and benefits were discounted at 3% annually. No prophylaxis resulted in a life expectancy of 13.36 quality-adjusted life years (QALY) at an ADLC of $4,538. In comparison, prophylaxis with TMP/ SMX alone increased the QALY to 13.54 and was cost saving, with an ADLC of $3,304. The addition of pentamidine in patients who had an ADR to TMP/SMX resulted in 13.61 QALY, with an ADLC of $7,428. Compared with TMP/SMX alone, TMP/SMX followed by pentamidine increased the QALY by 0.07 at an incremental cost of $58,037 per QALY. Both TMP/SMX alone and TMP/SMX followed by pentamidine prophylaxis strategies dominated the no prophylaxis strategy until the incidence of PCP fell below 0.2% and 2.25%, respectively. Institution of pentamidine therapy for patients with a TMP/SMX ADR increased quality-adjusted life expectancy compared with that with TMP/ SMX alone until the incidence of PCP rose above 7.5%. Prophylaxis using TMP/SMX alone increased life expectancy and reduced cost for patients with WG receiving immunosuppressive therapy. Replacing TMP/SMX with monthly aerosolized pentamidine in cases of ADR further increased life expectancy, although at an increased cost.

Immunomodulation with FK506 around the time of intravenous re-administration of an adenoviral vector facilitates gene transfer into primed rat liver.

Although adenoviruses are an attractive vehicle for gene transfer into tissues including various tumors, in vivo adenoviral administration elicits a neutralizing antibody response which eliminates or substantially reduces the efficacy of subsequent treatments. Transiently immunosuppressive strategies at the time of initial adenoviral exposure have shown to prevent the formation of neutralizing antibodies and permit the successful adenoviral readministration in animals. Initial treatment in humans may, however, correspond to adenoviral readministration into animals, because the exposure to wild-type adenoviruses is common in humans. In the present study, we infused Adex1CAlacZ adenoviruses carrying the lacZ gene into the tail vein of rats, and examined whether a transient treatment with the immunosuppressant FK506 around the time of i.v. readministration of adenoviruses could induce the re-expression of the lacZ gene in animals primed with adenoviruses. Although i.v. infusion of adenoviruses carrying the lacZ gene resulted in transiently high levels of transgene expression in rat liver, i.v. reinfusion of adenoviruses failed to induce detectable levels of transgene expression. Conversely, when animals were treated transiently with FK506 around the time of adenoviral reinfusion, development of neutralizing antibodies and antigen-specific T cell proliferation in response to adenoviral reinfusion were significantly suppressed, and re-expression of the transgene was achievable.

A Calorimetric Approach for Evaluation of Fluid-to-Particle Heat Transfer Coefficient Under Tube-Flow Conditions

A calorimetric approach was used to evaluate the bulk temperature of moving particles, and the convective fluid-to-particle heat transfer coefficients (hfp) were evaluated under continuous tube-flow conditions. The technique consisted of introducing a particle at an upstream location into a holding tube, through which a carrier fluid circulated under prestabilized temperature and flow conditions, and retrieving it from a downstream location at a known time interval. The particle was transferred immediately into a specially constructed calorimeter and its bulk temperature was determined upon equilibration. The technique was calibrated using thermocouple equipped particles subjected to various time-temperature treatments. Since the medium temperature, particle initial temperature, exposure time and thermophysical properties were known, the associated hfpcould be computed using an iterative numerical technique for the evaluated bulk temperature of the particle. The hfpvalues obtained from using the calorimetric approach were comparable to those obtained from traditional techniques involving thermocouple equipped particles. Higherhfp values were associated with moving particles, as compared with stationary particles, particles of larger size and fluid flowing at higher rates.

Colour and AOX removal from pulping effluents by algae

A mixed culture of algae was used to treat pulping mill effluent in terms of removing both colour and adsorbably organic halides (AOX). The removal of AOX from pulping effluent increased with increasing initial colour value of the effluent. However, for the total mill effluent (composed of both pulping and bleaching effluents), AOX removal was found to be independent of initial colour value, and was around 70%. Up to 80% removal of colour from pulping effluent was achieved within 30 days under continuous lighting conditions. It was found that algae reduced the colour of pulping effluent of relatively low initial colour more efficiently than that of high initial colour. Under simulated field lighting conditions, up to 60% colour removal from pulping effluent was observed after 60 days of exposure, whereas for the total mill effluent it was up to 64% after 45 days. Total organic carbon and lignin (UVA280) were also removed to a significant extent, suggesting that the mechanism of colour removal might not be transformation of the coloured lignin molecules to non-coloured ones. Analysis of alkaline extraction of the algal biomass and material balance findings indicated that the main colour removal mechanism was metabolism rather than adsorption. The experimental results were also analysed using multiple regression techniques and a mathematical model was developed to express the removal of colour from pulping effluents in terms of initial colour value, exposure time and lighting periods as well as interactions between these variables.