Reduction In Peak Area Research Articles

Effect of Ultrasound and Freeze‐Drying to Enhance the Extraction of Phenolic Compounds in Dragon Fruit Peels and Apply Them in Edible Starch‐Based Films

ABSTRACTIn this study, dragon fruit peels were subjected to different times (5, 10, 15, 20 and 25 min) of ultrasound pretreatment (4.870 W m−2/25°C) and then freeze‐drying (FD) (−56°C/48 h) to obtain powder particles, which underwent physical–chemical, functional and structural characterisation. Additionally, the extraction of total phenolic compound (TPC) was evaluated through ultrasound‐assisted kinetics and mechanical agitation. Finally, films based on black rice starch were developed with the addition (0.5, 1.5 and 2.5%) of dragon fruit peel powder particles, and their physical, barrier, antioxidant, structural and mechanical properties were evaluated. The results obtained showed that all particles had low water content (4.21%–6.58%) and high solubility (84.62%–88.73%) with a reduction in particle size (23.21–39.32 μm). In the extraction of TPC, the synergistic effect of the tested conditions increased efficiency, reaching 686.66 mg GAE/100 g for pretreated dragon fruit peel powder particles (25 min) in 180 min of extraction. Furthermore, the type ‘A’ crystallinity structure did not change significantly with pretreatment, but there was a reduction in peak area, reflecting on relative crystallinity, with a maximum decrease of 29.04%. The starch‐based films produced with 2.5% dragon fruit peel powder particles showed low solubility (28.72%) and low water vapour permeability (5.03 × 10−8 g mm s−1 m2 Pa), however, they contained higher levels of TPC (31.78 mg GAE/100 g film) and antioxidant activity (8.17 μmol TE/g film) that were easily migrated in aqueous medium. Furthermore, they also presented low values of tensile strength at break (3.41 MPa) and Young's modulus (4.18 MPa), as well as a high value of elongation at break (45.82%). Finally, our results highlight the potential of ultrasound as a pretreatment for FD of dragon fruit peels, paving the way for the development of rice starch‐based food packaging.

Eco-friendlier and sustainable natural-based additives for poly(vinyl chloride)-based composites

This work presents novel natural-based and solvent-free additives for poly(vinyl chloride) (PVC), namely calcium soaps, obtained for the first time from naturally occurring epoxidized soybean and linseed oils (ESO/ELO); and biogenic calcium carbonate, obtained from chicken eggshells (EG) after different acid and/or thermal pre-treatments. Results show that these additives were able to: i) reduce the concentration of volatile organic compounds released from PVC films, including alcohols, aldehydes, esters and phthalates (97,95,90 and 84% chromatographic peak area reduction, respectively), originating safer materials; ii) improve the long-term thermal stability of PVC-based materials, while maintaining their mechanical performance and when compared to control samples formulated with a high-performance commonly employed solvent-based thermal stabilizer. Films formulated with ESO-based calcium soaps and with EG powders treated with acid and thermal treatment (200 °C) presented the best performance in terms of heat aging and long-term thermal stability. The former also slightly improved the thermomechanical properties of the films indicating that these additives are also working as secondary plasticizers for PVC. This work gives an important contribution towards the safety and sustainability of high-performance PVC-based materials, by allowing the substitution of commercially available thermal stabilizers by new eco-friendlier and safer alternatives obtained from renewable sources.

Biodegradation of Escravos light crude oil by three indigenous bacteria, isolated from mechanic workshop in Lagos State Nigeria

Introduction: Petroleum hydrocarbons can be degraded by microorganisms such as bacteria, fungi, yeast and microalgae. However, bacteria play an imperative role in hydrocarbon degradation. Microorganisms are endowed with metabolism machinery to use petroleum products as a carbon and energy source Aims: The aim of the study is to isolate hydrocarbon degrading bacteria from hydrocarbon polluted site (mechanic workshops) in Lagos state. Materials and Methods: The physical, chemical and microbiological properties of the three soil sample were analyzed using standard procedure. Hydrocarbon degraders were isolated on 1% crude oil mineral salt medium via enrichment technique. The best hydrocarbon degrader were identified on the basis of their colonial morphology, biochemical characteristics and complemented with analytical profile index (API) kit. Hydrocarbon degradation were monitored using total viable count and residual oil was determined by Gas Chromatography equipped with Flame Ionized detector (GC-FID). Results: Alkaline pH were observed for all three soil samples, the total nitrogen detected were 0.07, 0.04 and 0.1. The total heterotrophic bacteria (THB) estimated were 3 x 1010, 6.5 x 109 and 1.7 x 1010 cfu/ml while the total hydrocarbon utilizing bacteria estimated via vapour phase were 1.89 x 106 , 4x104 and 9.62 x 107 cfu/ml for Ikeja, Iyana-Iba and Mushin sample. The organisms had a generation time of 5.56, 9.09 and 10.9 (d), the degradation half-life were 3.85, 6.3 and 7.5 (d) respectively. Over 60% hydrocarbon degradation were determined within 10 days for all three isolates. The Gc-fid prints shows reduction in peak area of various hydrocarbon fractions with a decrease in pH of the medium. Conclusion: The study showed that hydrocarbon degraders are ubiquitously distributed in the hydrocarbon polluted soil sample. Their degradation potential can be optimized so as curtail the adverse effect of petroleum in the environment

Determination of gastrodin activity inhibition on acetylcholinesterase by capillary electrophoresis

Alzheimer's disease (AD) is the most common cause of dementia in elderly individuals. Currently, acetylcholinesterase inhibitors (AChEI) are the most effective clinical treatment for AD. AChEIs in natural products may have therapeutic potential and should be screened for use in AD treatment. The authors describe a simple and reliable method for AChEI screening by capillary electrophoresis (CE). A hexadimethrine bromide (HDB) solution was pushed into a capillary (0.015 MPa×10 s) and incubated for 5 min. The capillary was flushed with deionized water for 5 min to remove free HDB, followed by plugging with an acetylcholinesterase (AChE) solution. After a 5 min incubation, the AChE was immobilized on the positively charged coating by ion binding, and the micro-reactor was created. The substrate solution, acetylthiocholine iodide (AThC), was injected into the capillary and incubated in the micro-reactor for 1 min. The unreacted substrate and the enzymolysis product were separated by CE. Gastrodin, an important component of Gastrodia elata, can inhibit AChE activity. After a certain amount of gastrodin was spiked into the substance solution, the peak area of the product decreased. Greater peak area reduction indicated stronger inhibition of AChEI. We observed good reproducibility of the product peak, with relative standard deviation (RSD) values less than 5.3%. The micro-reactor can be reused up to 300 times, which greatly improves efficiency. When the concentration of gastrodin was 5.24 μmol/L, the inhibition rate of AChE reached 64.8%. The IC50 of gastrodin was (2.26±0.14) μmol/L (R2=0.9983), which was consistent with the result of traditional UV method (2.09±0.18 μmol/L). If the function of the micro-reactor deteriorates, it can be conveniently renewed by flushing the column to remove the enzyme and repeating the AChE immobilization protocol. The proposed method is simple, efficient, and low cost, and can be used to screen AChEI from natural products, thus contributing to the improvement of AD treatment.

Comprehensive profiling of minor tyrosinase inhibitors from Gastrodia elata using an off-line hyphenation of ultrafiltration, high-speed countercurrent chromatography, and high-performance liquid chromatography

In the present study, a novel hyphenation of ultrafiltration (UF), high-speed countercurrent chromatography (HSCCC), and high-performance liquid chromatography (HPLC) was developed for comprehensive profiling and characterization of the minor tyrosinase inhibitors from Gastrodia elata (GE). A small quantity of GE extract was first fractionated by HSCCC, using elution solvents with a wide range of polarities to enrich minor compounds; then, the fractions were profiled by UF-HPLC to generate a comprehensive 2D chromatogram of the distribution of bioactive components. To determine the binding affinities of these bioactive components, the binding degree (BD%) was calculated by peak area reduction, in which a higher BD% indicates a higher binding affinity to tyrosinase. Among the 212 metabolites, 49 were identified as tyrosinase ligands, 17 of which showed high binding affinity. According to the 2D chromatogram, these 17 candidates were isolated by semiprep-HPLC for characterization of their structure using off-line hyphenated ultraviolet (UV), electron ionized mass spectrometry (EIMS), proton nuclear magnetic resonance (1H NMR). Their activities were further validated by functional assays. In conclusion, the approach developed here can comprehensively identify both major and minor bioactive constituents from natural products, and provide meaningful suggestions to direct further research. Compared to conventional approaches, this approach, developed by hyphenating several techniques, is a highly efficient means for comprehensive profiling of potent minor compounds extracted from natural products.

Transdermal Protein Delivery Using Choline and Geranate (CAGE) Deep Eutectic Solvent.

Transdermal delivery of peptides and other biological macromolecules is limited due to skin's inherent low permeability. Here, the authors report the use of a deep eutectic solvent, choline and geranate (CAGE), to enhance topical delivery of proteins such as bovine serum albumin (BSA, molecular weight: ≈66 kDa), ovalbumin (OVA, molecular weight: ≈45 kDa) and insulin (INS, molecular weight: 5.8 kDa). CAGE enhances permeation of BSA, OVA, and insulin into porcine skin ex vivo, penetrating deep into the epidermis and dermis. Studies using tritium-labeled BSA and fluorescein isothiocyanate labeled insulin show significantly enhanced delivery of proteins into and across porcine skin, penetrating the skin in a time-dependent manner. Fourier transform IR spectra of porcine stratum corneum (SC) samples before and after incubation in CAGE show a reduction in peak area attributed to SC lipid content, suggesting lipid extraction from the SC. Circular dichroism confirms that CAGE does not affect insulin's secondary conformation. In vivo studies in rats show that topical application of 10 U insulin dispersed in CAGE (25 U kg-1 insulin dose) leads to a highly significant 40% drop in blood glucose levels in 4 h that is relatively sustained for 12 h. Taken together, these studies demonstrate that CAGE is a promising vehicle for transdermal delivery of therapeutic proteins; specifically, as a noninvasive delivery alternative to injectable insulin for the treatment of diabetes.

Biosurfactant production and concomitant hydrocarbon degradation potentials of bacteria isolated from extreme and hydrocarbon contaminated environments

Amongst the total forty-seven bacterial isolates, eleven potent biosurfactant producing and concomitant hydrocarbon degraders were obtained after primary screening involving drop collapse method (DCM) and Oil-spreading method (OSM) followed by secondary screening comprising of Haemolytic assay (HA), Cetyl trimethyl ammonium bromide (CTAB) assay, Surface tension (ST), Emulsification index (E24) and Emulsification activity (EA). 16S-rRNA sequencing and phylogenetic analysis revealed the presence of Achromobacter, Bacillus, Citrobacter, Lysinibacillus, Ochrobactrum and Pseudomonas. Two genera, Achromobacter (PS1) (observed for the first time) and Bacillus (SLDB1) were found to be glycolipid producers as evident by TLC, FT-IR and GC–MS chromatograms. The surface tension values were 30.43mN/m and 31.10mN/m with (E24) of 69.90% and 65.23% respectively. Similarly the TLC, FT-IR and GC–MS results of the other two genera Ochrobactrum (GREW1) and Bacillus (SB2) confirmed them as lipopeptide biosurfactant producers with surface tension values of 31.14mN/m and 28.16mN/m and (E24) of 59.51% and 61.35% respectively. Qualitative 2,6-Dichlorophenol Indophenol (2,6-DCPIP) and quantitative methods for hydrocarbon degradation revealed that Achromobacter sp. (PS1) showed a maximum degradation (46.32%) of 2% (w/v) crude oil with 70.77% and 77.17% reduction in peak area of aliphatic and aromatic fractions respectively with simultaneous lowering of surface tension from 59.27mN/m (control) to 32.43mN/m in 7days. In case of Achromobacter sp. (PS1) and Bacillus sp. (SB2 and SLDB1), glucose supported biosurfactant production, whereas in Ochrobactrum sp. (GREW1) glucose along with 1% diesel enhanced biosurfactant production. This signifies the role of substrate in the nature of biosurfactants produced.

Profiling of urinary bile acids in piglets by a combination of enzymatic deconjugation and targeted LC-MRM-MS

We present a method using a combination of enzymatic deconjugation and targeted LC-multiple reaction monitoring (MRM)-MS analysis for analyzing all common bile acids (BAs) in piglet urine, and in particular, for detecting conjugated BAs either in the absence of their standards, or when present in low concentrations. Initially, before enzymatic deconjugation, 19 unconjugated BAs (FBAs) were detected where the total concentration of the detected FBAs was 9.90 μmol/l. Sixty-seven conjugated BAs were identified by LC-MRM-MS analysis before and after enzymatic deconjugation. Four enzymatic assays were used to deconjugate the BA conjugates. FBAs in urine after cholylglycine hydrolase/sulfatase treatment were 33.40 μmol/l, indicating the urinary BAs were comprised of 29.75% FBAs and 70.25% conjugated BAs in single and multiple conjugated forms. For the conjugates in single form, released FBAs from cholylglycine hydrolase deconjugation indicated that the conjugates with amino acids were 14.54% of urinary BAs, 16.27% glycosidic conjugates were found by β-glucuronidase treatment, and sulfatase with glucuronidase inhibitor treatment liberated FBAs that constituted 16.67% of urinary BAs. Notably, chenodeoxycholic acid (CDCA) was initially detected only in trace amounts in urine, but was found at significant levels after the enzymatic assays above. These results support that CDCA is a precursor of γ-muricholic acid in BA biosynthesis in piglets.

Syntrophic co-culture of Bacillus subtilis and Klebsiella pneumonia for degradation of kraft lignin discharged from rayon grade pulp industry

In order to search the degradability of kraft lignin, the potential bacterial strains Bacillus subtilis (GU193980) and Klebsiella pneumoniae (GU193981) were isolated, screened and applied in axenic and co-culture conditions. Results revealed that mixed culture showed better decolorization efficiency (80%) and reduction of pollution parameters (COD 73% and BOD 62%) than axenic culture. This indicated syntrophic growth of these two bacteria rather than any antagonistic effect. The HPLC analysis of degraded samples of kraft lignin has shown the reduction in peak area compared to control, suggesting that decrease in color intensity might be largely attributed to the degradation of lignin by isolated bacteria. Further, the GC–MS analysis showed that most of the compounds detected in control were diminished after bacterial treatment. Further, the seed germination test using Phaseolus aureus has supported the detoxification of bacterial decolorized kraft lignin for environmental safety. All these observations have revealed that the developed bacterial co-culture was capable for the effective degradation and decolorization of lignin containing rayon grade pulp mill wastewater for environmental safety.

Polymer-coated sample cup for quantitative analysis of semi-volatile phthalates in polymeric materials by thermal desorption-gas chromatography–mass spectrometry

A new “polymer-coated” sample cup useful for the analysis of phthalates in polymeric materials by thermal desorption (TD)-GC/MS using a temperature programmable furnace type pyrolyzer as a TD device was developed to suppress the emission of semi-volatile phthalates such as dimethyl phthalate (DMP) and diethyl phthalate (DEP) during the measurements. The inner surface of a sample cup was coated by polymers which act as a sorbent for the phthalates. Three polymers, polyvinyl chloride, polystyrene and poly (methyl methacrylate), were chosen as the coating polymers. A mixture of ten phthalates including DMP and DEP was used as the test sample to estimate the performance of the sample cups. When a conventional sample cup without any polymer coating was used, 90 and 50% reductions in the peak areas of DMP and DEP were respectively observed at the waiting time of 200min. On the contrary, no reduction of peak area of DMP and DEP during the same waiting time was observed with any one of the three coating polymers at the proper polymer film thickness. These results suggest that the polymer-coated sample cup suppresses the emission of semi-volatile phthalates and is effective for the analysis of phthalates containing DMP and DEP by TD-GC/MS.

Bacterial decolorization and detoxification of black liquor from rayon grade pulp manufacturing paper industry and detection of their metabolic products

This study deals with the decolorization of black liquor (BL) by isolated potential bacterial consortium comprising Serratia marcescens (GU193982), Citrobacter sp. (HQ873619) and Klebsiella pneumoniae (GU193983). The decolorization of BL was studied by using the different nutritional as well as environmental parameters. In this study, result revealed that the ligninolytic activities were found to be growth associated and the developed bacterial consortium was efficient for the reduction of COD, BOD and color up to 83%, 74% and 85%, respectively. The HPLC analysis of degraded samples of BL has shown the reduction in peak area compared to control. Further, the GC–MS analysis showed that, most of the compounds detected in control were diminished after bacterial treatment while, formic acid hydrazide, 4-cyclohexane-1,2-dicarboxylic acid, carbamic acid, 1,2-benzenedicarboxylic acid and erythropentanoic acid were found as new metabolites. Further, the seed germination test using Phaseolus aureus has supported the detoxification of bacterial decolorized BL.

Relationships between physiological characteristics and trace metal body burdens of banded garden spiders Argiope trifasciata (Araneae, Araneidae)

Banded garden spiders ( Argiope trifasciata) were collected at the Ballona Wetlands, a metal contaminated salt marsh. The relationship between spider body size and individual metal loads was investigated. Biochemical markers were identified in spider fecal material and found to correlate to body metal levels. Body metal dry weight concentrations of Cd, Cr, Cu, Zn and total metals in female A. trifasciata exhibited distinct patterns of spatial and annual variation during 2006 and 2007. Spider body size was homogeneous across sites in both years, while increased Cd and Cr concentrations were sometimes associated with a reduction in spider size, though the influence of Cr was quite minor. Spiders with higher body Cu levels showed a reduction in peak area for hypoxanthine and an un-identified component in fecal material chromatograms. Spatial and annual differences in metal bioaccumulation are likely mediated by variation in site-specific environmental parameters and rainfall, while the negative relationships between body size and metal levels are presumably a consequence of a spider's expenditure of energy for metal tolerance mechanisms vs. foraging and growth. Finally, correlating body metal levels with excreta products constitutes a novel method to non-invasively predict metal levels in spiders.

Varying nanoparticle pseudostationary phase plug length during capillary electrophoresis

Capillary electrophoresis based separations of the hypothesized Parkinson's disease biomarkers dopamine, epinephrine, pyrocatechol, L-3,4-dihydroxyphenylalanine (L-DOPA), glutathione, and uric acid are performed in the presence of a 1 nM 11-mercaptoundecanoic acid functionalized gold (Au@MUA) nanoparticle pseudostationary phase plug. Au@MUA nanoparticles are monitored in the capillary and remain stable in the presence of electrically-driven flow. Migration times, peak areas, and relative velocity changes (vs. no pseudostationary) are monitored upon varying (1) the Au@MUA nanoparticle pseudostationary phase plug length at a fixed separation voltage and (2) the separation voltage for a fixed Au@MUA nanoparticle pseudostationary phase plug length. For instance, the migration times of positively charged dopamine and epinephrine increase slightly as the nanoparticle pseudostationary phase plug length increases with concomitant decreases in peak areas and relative velocities as a result of attractive forces between the positively charged analytes and the negatively charged nanoparticles. Migration times for neutral pyrocatechol and slightly negative L-DOPA did not exhibit significant changes with increasing nanoparticle pseudostationary plug length; however, reduction in peak areas for these two molecules were evident and attributed to non-specific interactions (i.e. hydrogen bonding and van der Waals interactions) between the biomarkers and nanoparticles. Moreover, negatively charged uric acid and glutathione displayed progressively decreasing migration times and peak areas and as a result, increased relative velocities with increasing nanoparticle pseudostationary phase plug length. These trends are attributed to partitioning and exchanging with 11-mercaptoundecanoic acid on nanoparticle surfaces for uric acid and glutathione, respectively. Similar trends are observed when the separation voltage decreased thereby suggesting that nanoparticle-biomarker interaction time dictates these trends. Understanding these analyte migration time, peak area, and velocity trends will expand our insight for incorporating nanoparticles in separations.

SPME–GC Determination of an Inhalation Anesthetic, Isoflurane in Bulk and Nanoemulsion Dosage Form

A stability-indicating gas chromatographic (GC) method was developed and validated for quantitative determination of an halogenated volatile anesthetic isoflurane (ISO) in the presence of degradation products generated under stress conditions. The sample concentration was carried out by means of solid-phase microextraction (SPME) using a 100-μm polydimethylsiloxane (PDMS) fiber, desorbed inside the GC inlet port and analyzed using a GS-Gaspro (30 m × 0.32 mm) capillary column with flame ionization detection (FID). The response was linear over a range of 3.75 to 30.04 μg mL−1 (r = 0.9996). The specificity and stability-indicating capability of the method was verified subjecting ISO to hydrolytic, oxidative, photolytic, and thermal stress conditions. The method showed good recovery (99.54%) with low intra- and inter-day relative standard deviation (RSD) (≤2.5%). A considerable degradation occurred under stress conditions evidenced by an ISO peak area reduction while the degradation product was not detectable. There was no interference of the excipients in the determination of the drug. Thus, the proposed method was found to be stability-indicating and can be used for routine analysis for quantitative determination of ISO liquid anesthetic.

Biodegradation of the major color containing compounds in distillery wastewater by an aerobic bacterial culture and characterization of their metabolites

This study deals the biodegradation of the major color containing compounds extracted from distillery wastewater (DWW) by an aerobic bacterial consortium comprising Bacillus licheniformis (DQ79010), Bacillus sp. (DQ779011) and Alcaligenes sp. (DQ779012) and characterization of metabolic products. The degradation of color containing compounds by bacteria was studied by using the different carbon and nitrogen sources at different environmental conditions. Results revealed that the bacterial consortium was efficient for 70% color removal in presence of glucose (1.0%) and peptone (0.1%) at pH 7.0 and temperature 37 degrees C. The HPLC analysis of control and bacterial degraded samples has shown the reduction in peak area as well as shifting of peaks compared to control indicating the bacterial degradation as well as transformation of color containing compounds from DWW. The comparative LC-MS-MS and other spectrophotometric analysis has shown the presence of dihydroxyconiferyl alcohol, 2, 2'-bifuran-5-carboxylic acid, 2-nitroacetophenone, p-chloroanisol, 2, 3-dimethyl-pyrazine, 2-methylhexane, methylbenzene, 2, 3-dihydro-5-methylfuran, 3-pyrroline, and acetic acid in control samples that were biodegraded and biotransformed into 2-nitroacetophenone, p-chloroanisol, 2, 2'-bifuran, indole, 2-methylhexane, and 2, 3-dihydro-5-methylfuran by bacterial consortium. In this study, it was observed that most of the compounds detected in control samples were diminished from the bacterial degraded samples and compounds 2, 2'-bifuran and indole with molecular weight 134 and 117 were produced as new metabolites during the bacterial degradation of color containing compounds from DWW.

Isolation and characterization of potential aerobic bacteria capable for pyridine degradation in presence of picoline, phenol and formaldehyde as co-pollutants

Pyridine, heterocyclic aromatic compound is known to be toxic, carcinogenic and teratogenic to several living organisms. In this study, two aerobic bacteria ITRCEM1 and ITRCEM2 capable for pyridine degradation were isolated and characterized as Bacillus cereus (DQ435020) and Alcaligenes faecalis (DQ435021), respectively. For pyridine degradation, mixed bacterial culture was found more effective compared to axenic culture ITRCEM1 and ITRCEM2 degrading 94.23, 67.84, and 83.35% pyridine, respectively, at 144 h incubation period at pH 7.0 ± 0.1, temp 37 ± 2°C and shaking rate 125 rpm in MSM containing 1% glucose and 0.2% peptone as carbon and nitrogen source, respectively. The presence of phenol and formaldehyde in MSM has shown inhibitory effect on pyridine degradation whereas picoline has favored the bacterial growths and pyridine degradation. Further, the HPLC analysis has shown the reduction in peaks compared to controls, indicating that reduction in peak area might be largely attributed to the bacterial degradation of pyridine by bacterial catabolic enzymes.

Isolation and characterization of aerobic bacteria capable of the degradation of synthetic and natural melanoidins from distillery effluent

Melanoidins, complex biopolymer of amino-carbonyl compounds are the major coloring and polluting constituents of distillery wastewaters. In this study, three aerobic melanoidin-degrading bacteria (RNBS1, RNBS3 and RNBS4) were isolated from soil contaminated with distillery effluent and characterized as Bacillus licheniformis (RNBS1), Bacillus sp. (RNBS3) and Alcaligenes sp. (RNBS4) by biochemical tests and 16S rRNA gene sequence analysis. The degradation of synthetic and natural melanoidins was studied by using the axenic and mixed bacterial consortium. Results have revealed that the mixed consortium was more effective compared to axenic culture decolorizing 73.79 and 69.83% synthetic and natural melanoidins whereas axenic cultures RNBS1, RNBS3 and RNBS4 decolorized 65.88, 62.56 and 66.10% synthetic and 52.69, 48.92 and 59.64% natural melanoidins, respectively. The HPLC analysis of degraded samples has shown reduction in peak areas compared to controls, suggesting that decrease in color intensity might be largely attributed to the degradation of melanoidins by isolated bacteria.

Effects of Treatment for Manipulation of Teeth and Er:YAG Laser Irradiation on Dentin: A Raman Spectroscopy Analysis

The main purpose of this study was to evaluate the utility of Raman spectroscopy analysis as a research tool to study the effects of Er:YAG laser etching on dentin mineral and organic components. A secondary aim was to study the effects of the decontamination process and the storage procedure on dentin components. There are no spectroscopy reports relating the effects of Er:YAG laser irradiation as an alternative to acid etching and the manipulation process on the dentin structure. Twelve non-carious human third molars were divided in two main groups: stored in thymol solution (group A, n = 6) or autoclaved (group B, n = 6). The specimens were either etched with 37% phosphoric acid (control subgroup) or irradiated with Er:YAG laser. Irradiated samples were divided into the following subgroups: I, II, and III (80 mJ, 3 Hz, 30 sec; 120 mJ, 3 Hz, 30 sec; and 180 mJ, 3 Hz, 30 sec, respectively). Samples were analyzed by Raman spectroscopy. The mineral and organic dentin contents were more affected in autoclaved teeth than in the specimens stored in thymol. Peak area reduction in group A specimens treated with phosphoric acid and pulse energy of 80 mJ were the most conservative surface treatments regarding changes in the peak area of organic and inorganic dentin components. The autoclaving process and pulse energies of 120 and 180 mJ produced greater reduction of organic and inorganic contents in dentin, associated with greater reduction in the areas of 968, 1077, 1460, and 1670 cm(1) Raman peaks.

Characterization of the phytochemicals and antioxidant properties of extracts from Teaw ( Cratoxylum formosum Dyer)

The leaves of the Thai vegetable, Teaw ( Cratoxylum formosum Dyer) were extracted with ethanol to provide an extract that had antioxidant properties. The composition of the extract was studied by high-performance liquid chromatography with a diode array detector, and by electrospray ionization mass spectrometry. The main antioxidant component (peak 1) was chlorogenic acid, which was present at 60% of the extract. Three minor components were present at 7%, 3% and 2%, and other components that were present at lower concentrations were also observed. Treatment of the Teaw extract with 2,2-diphenyl-1-picrylhydrazyl radical (DPPH ) caused a similar reduction in peak area of 55.2–58.1% for chlorogenic acid and the three minor components, indicating that these components had common structural features. Component 2 was identified as dicaffeoylquinic acid, and compounds 3 and 4 were identified as ferulic acid derivatives. The radical-scavenging activity of the Teaw extract was compared with α-tocopherol, BHT and chlorogenic acid, using the DPPH and 2,2′-azinobis (3-ethylbenzothialozinesulfonic acid) radical cation (ABTS + ) assays. The Teaw extract scavenged both free radicals more strongly than did α-tocopherol and BHT, and the activity of the extract was consistent with the concentration of chlorogenic acid that was present, confirming that this component is a major contributor to the antioxidant activity. The acute toxicity of the Teaw leaf extract was investigated in mice, and it was found that the LD 50 of the extract was >32 g/kg. Consequently, this plant is a promising source of a natural food antioxidant.

Wet Scrubber Analysis of Volatile Organic Compound Removal in the Rendering Industry

The promulgation of odor control rules, increasing public concerns, and U.S. Environmental Protection Agency (EPA) air regulations in nonattainment zones necessitates the remediation of a wide range of volatile organic compounds (VOCs) generated by the rendering industry. Currently, wet scrubbers with oxidizing chemicals are used to treat VOCs; however, little information is available on scrubber efficiency for many of the VOCs generated within the rendering process. Portable gas chromatography/mass spectrometry (GC/MS) units were used to rapidly identify key VOCs on-site in process streams at two poultry byproduct rendering plants. On-site analysis was found to be important, given the significant reduction in peak areas if samples were held for 24 hr before analysis. Major compounds consistently identified in the emissions from the plant included dimethyl disulfide, methanethiol, octane, hexanal, 2-methylbutanal, and 3-methylbutanal. The two branched aldehydes, 2-methylbutanal and 3-methylbutanal, were by far the most consistent, appearing in every sample and typically the largest fraction of the VOC mixture. A chlorinated hydrocarbon, methanesulfonyl chloride, was identified in the outlet of a high-intensity wet scrubber, and several VOCs and chlorinated compounds were identified in the scrubbing solution, but not on a consistent basis. Total VOC concentrations in noncondensable gas streams ranged from 4 to 91 ppmv. At the two plants, the odor-causing compound methanethiol ranged from 25 to 33% and 9.6% of the total VOCs (v/v). In one plant, wet scrubber analysis using chlorine dioxide (ClO2) as the oxidizing agent indicated that close to 100% of the methanethiol was removed from the gas phase, but removal efficiencies ranged from 20 to 80% for the aldehydes and hydrocarbons and from 23 to 64% for total VOCs. In the second plant, conversion efficiencies were much lower in a packed-bed wet scrubber, with a measurable removal of only dimethyl sulfide (20–100%).