Repetitive Extraction Research Articles

Repetitive Transient Extraction Using the Optimized SES Entropy Wavelet for Fault Diagnosis of Rotating Machinery

Repetitive transients are usually generated in the monitoring data when a fault occurs on the machinery. As a result, many methods such as kurtogram and optimized Morlet wavelet and kurtosis method are proposed to extract the repetitive transients for fault diagnosis. However, one shortcoming of these methods is that they are constructed based on the index of kurtosis and are sensitive to the impulsive noise, leading to failure in accurately diagnosing the fault of the machinery operating under harsh environment. To address this issue, an optimized SES entropy wavelet method is proposed. In the proposed method, the optimized parameters including bandwidth and central frequency of Morlet wavelets are selected. Then, based on the wavelet coefficients decomposed using the optimized Morlet wavelet, the SES entropy is calculated to select the scales of wavelet coefficients. Finally, the repetitive transients are reconstructed based on the denoising wavelet coefficients of the selected scales. One simulation case and vibration data collected from the experimental setup are used to verify the effectiveness of the proposed method. The simulated and experimental analyses showed that the signal-to-noise ratio (SNR) of the proposed method has the largest value. Specifically, the SNR in the experimental analysis of the proposed method is 0.6, while that of the other three methods is 0.043, 0.0065, and 0.0045, respectively. Therefore, the result shows that the proposed method is superior to the traditional methods for repetitive transient extraction from the vibration data suffered from impulsive noise.

Non-destructive extraction of lipids from Botryococcus braunii and its potential to reduce pond area and nutrient costs

The production of oil from microalgae is a process with a long way to go before reaching commercial viability. High costs associated with harvesting and solvent extraction make it difficult to compete with fossil fuel. The in-situ, non-destructive, repetitive extraction of lipids from Botryococcus braunii (milking) offers an alternative to the conventional microalgal-oil production process, with significantly reduced nutrient, dewatering and cultivation costs. Here, we compare low shear column solvent extraction with high shear stirred tank solvent extraction to ascertain which is better suited to a repetitive extraction process using B. braunii and carry out a preliminary economic analysis on the nutrient costs and raceway pond area requirements once scaled to industrial production. Stirred tank extraction with heptane resulted in five times higher productivities than that of column solvent extraction. Using this to generate an extraction model we found a lipid productivity of 104 mg L-1 day-1 was possible, six times greater than that of previous repetitive extraction studies. Thanks to the high lipid content of the B. braunii biomass generated in the recovery phase, when scaled to open raceway ponds, a lipid productivity of 13.4 g m-2 day-1 can be predicted. With this productivity, an estimated combined carbon, nitrogen and phosphorus cost of $2.52 L-1 of oil produced and a cultivation pond area of 3.53 km2 (assuming an annual oil production of 15,900 m3 year-1) is predicted, corresponding to reductions when compared to conventional extraction of 40% and 50% respectively. This repetitive extraction process provides an alternative method for the production of 3rd generation biofuels without the need to harvest and dewater algal biomass with significant reductions in nutrient and pond area requirements.

Selective extraction of glutaric acid from biological production systems using n-butanol

Glutaric acid has numerous industrial applications and it could be used as a polymer building block. Glutaric acid can be produced by chemical or biological methods. Although the biological production of glutaric acid has attracted considerable attention, there are few effective and economical processes for recovering glutaric acid from water based systems. Herein, we investigated the selective extraction of glutaric acid via physical extraction using nine different solvents compared with trioctylamine/toluene as the reactive extraction, which is the only reported method for recovering glutaric acid from biological production systems. Comparisons of the extraction yield, purity, linear solvation energy relationship between the solvents, and reactant selectivity revealed n-butanol to be a suitable solvent for the extraction of glutaric acid, with a high extraction yield and selectivity obtained in less than 30min under optimized conditions. Furthermore, repetitive extraction allowed 98.4% of glutaric acid to be extracted from the aqueous phase with high solvent recovery and high purity, making this method suitable for practical application.

Repetitive extraction of botryococcene from Botryococcus braunii: a study of the effects of different solvents and operating conditions

As global temperatures continue to increase the move to renewable energy sources is becoming an essential step in achieving a sustainable future. Biofuels from microalgae, while still more expensive to produce than fossil fuels, are of great interest for the high microalgae biomass growth rates, high lipid content, relatively low water requirements, and ability to be grown on non-arable land. Botryococcus braunii is a freshwater green microalga which grows in colonies supported by an extracellular matrix (ECM) of liquid hydrocarbons. Recent studies have investigated the efficiency of non-destructive in situ solvent extraction of lipids from B. braunii with a variety of solvents. These lipids are encapsulated in a retaining wall coated by a sheath of amphiphilic fibrils which have been found to act as a barrier to solvents. By carrying out repeated in situ solvent extraction in a high shear environment, we found that access to the ECM can be significantly improved. Sustainable botryococcene and total lipid productivities respectively of 29.9 ± 8.5 and 71.3 ± 20.3 mg L−1 day−1 were achieved with heptane extraction, a shear rate of 415 s−1, initial culture density of 1.62 ± 0.12 g L−1, contact period of 4 h, and a recovery period of 3 days. Nutrient supplementation to replace those lost in the emulsion entrained biomass will be required to maintain a sustainable process. The combined presence of heptane with high shear proved to be an effective colony disruption method which could be an effective pre-treatment followed by a low shear, high solvent contact, and extraction method.

Hollow Nanoneedle-Electroporation System To Extract Intracellular Protein Repetitively and Nondestructively.

Techniques used to understand the dynamic expression of intracellular proteins are critical in both fundamental biological research and biomedical engineering. Various methods for analyzing proteins have been developed, but these methods require the extraction of intracellular proteins from the cells resulting in cell lysis and subsequent protein purifications from the lysate, which limits the potential of repetitive extraction from the same set of viable cells to track dynamic intracellular protein expression. Therefore, it is crucial to develop novel methods that enable nondestructive and repeated extraction of intracellular proteins. This work reports a hollow nanoneedle-electroporation system for the repeated extraction of intracellular proteins from living cells. Hollow nanoneedles with ∼450 nm diameter were fabricated by a material deposition and etching process, followed by integration with a microfluidic device. Long-lasting electrical pulses were coupled with the nanoneedles to permeate the cell membrane, allowing intracellular contents to diffuse into the microfluidic channels located below the cells via hollow nanoneedles. Using lactate dehydrogenase B (LDHB) as the model intracellular protein, the nanoneedle-electroporation system effectively and repeatedly extracted LDHB from the same set of cells at different time points, followed by quantitative analysis of LDHB via standard enzyme-linked immunosorbent assay. Our work demonstrated an efficient method to nondestructively probe intracellular protein levels and monitor the dynamic protein expression, with great potential to help understanding cell behaviors and functions.

Techno-economic analysis of milking of Botryococcus braunii for renewable hydrocarbon production

Microalgal biofuel has the potential to address two major global issues; 1) fulfill the rising energy demand of the world and 2) mitigate the increasing global warming by CO2 sequestration. Botryococcus braunii is a unique alga producing high hydrocarbon contents which can be hydrocracked into high quality fuel. However, there is a lack of interest on the use of B. braunii for biofuel production due to its slow growth rate, an influencing parameter in determining the economics of conventional algal fuel production process. Non-destructive extraction (milking) of B. braunii hydrocarbons is a process which enables the alga to reproduce the hydrocarbons reducing the requirement of fast growth of this alga for biofuel production. This study targets to establish a techno-economics of B. braunii milking to analyze its potential for the renewable hydrocarbon production. The minimum sales price (MSP) to achieve a 10% rate of return was estimated to be US$3.20 L−1 of B. braunii hydrocarbons for the base case scenario. The extraction efficiency and the hydrocarbon contents were found to be the major economy drivers of the process as a result of the additional sensitivity analysis performed to identify the most economic influencing parameters. The MSP has the potential of significant reduction (down to US$1.45 L−1) if a B. braunii with higher hydrocarbon contents is identified as long as the selected strain is suitable for milking and the higher non-destructive extraction efficiency is achieved. A resource assessment comparison was also made to evaluate the significance of the repetitive extraction versus the single extraction. The milking has the clear advantage over the conventional single extraction regarding resource consumption and the cost of the process.

A graphene oxide-based polymer composite coating for highly-efficient solid phase microextraction of phenols

Sensitivity and selectivity of the solid phase microextraction (SPME) in analysis are mostly determined by the coating material of the fiber used. Graphene oxide (GO) has attracted great attention because of its large specific surface area, rich oxygen functional groups, good dispersibility in aqueous solution and high reactivity. However, the low thermal stability of the functional groups limits the wide application of GO in SPME coating design. Highly cross-linked polyoxyethylene (POE) is a substrate widely used for composite material construction, which could significantly improve the thermal stability, water resistance as well as biocompatibility of the functional materials. In this study, we incorporated GO with highly cross-linked POE as a novel fiber coating material for SPME through the gluing approach. The obtained fiber possessed a wrinkled shape surface, which could increase the accessible surface area. In addition, the thermal and chemical stability of the fiber coating were also improved, rendering the fiber rigid enough for more than 100 repetitive extraction cycles. The performance of this developed SPME method for phenols was evaluated by headspace extraction of phenols in aqueous samples. Compared with three commercial fibers, the home-made fiber showed excellent extraction efficiencies towards phenols. Under the optimized conditions, it showed low detection limits (0.12–1.36 ng· L−1), good precision (<8.4%), good fiber-to-fiber repeatability (3.1%–8.1%), wide linear range (almost 5–1000 ng·L−1and correlation coefficients (R2) >99%), as well as good enrichment efficiencies (enrichment factors (EFs), 172–1752). Furthermore, the method was successfully applied in simultaneous analyses of five phenols for real water samples with satisfactory recoveries (81–113% for the Pearl River samples).

Superstructure optimization and energetic feasibility analysis of process of repetitive extraction of hydrocarbons from Botryococcus braunii – a species of microalgae

Microalgae are potential resources for producing renewable fuel; however, the process of fuel production from microalgae is itself highly energy consuming and not commercially feasible, yet. Repetitive non-destructive extraction, also called repetitive milking, is a novel method for production of hydrocarbons from Botryococcus braunii – a species of microalgae. In this study, superstructure optimization technique is used to analyse the energetic feasibility of the repetitive milking process and to find the suitable technology options for each stage involved. The repetitive milking process is found to be energetically positive with an average net energy ratio of two for the optimum route. Open pond, cylindrical sieve rotator filter and nanofiltration were found to be the optimum technologies for growth and hydrocarbon production, dewatering and solvent recovery stages, respectively. Belt filter press and vibratory screen filter for dewatering and distillation for solvent recovery are also found to be energetically feasible technologies.

Latifolicinin A from a Fermented Soymilk Product and the Structure-Activity Relationship of Synthetic Analogues as Inhibitors of Breast Cancer Cell Growth.

The functional components in soymilk may vary depending upon the fermentation process. A fermented soymilk product (FSP) obtained by incubation with the microorganisms of intestinal microflora was found to reduce the risk of breast cancer. Guided by the inhibitory activities against breast cancer cells, two cytotoxic compounds, daidzein and (S)-latifolicinin A, were isolated from the FSP by repetitive extraction and chromatography. Latifolicinin A is the n-butyl ester of β-(4-hydroxyphenyl)lactic acid (HPLA). A series of the ester and amide derivatives of (S)-HPLA and L-tyrosine were synthesized for evaluation of their cytotoxic activities. In comparison, (S)-HPLA derivatives exhibited equal or superior inhibitory activities to their L-tyrosine counterparts, and (S)-HPLA amides showed better cytotoxic activities than their corresponding esters. In particular, (S)-HPLA farnesyl amide was active to triple-negative MDA-MB-231 breast cancer cells (IC50 = 27 μM) and 10-fold less toxic to Detroit-551 normal cells.

RECOVERY OF ASPERGILLUS ENDO-GLUCANASE PRODUCED ON SOLID SUBSTRATE: A DOE BASED APPROACH

The endo-glucanase (E.C. 3.2.1.4) was produced by Aspergillus terreus adopting solid state fermentation (SSF) using agro residues as main substrate. To recover the enzyme from the fermented mass, different extraction liquids were tried and 10% aqueous solution of glycerol was found to be superior. When the selected extractant was applied at different ratio to the fermented solid mass, maximum enzyme was recovered at 1:5 (w/v) ratio. The other process parameters (time, temperature and mixing speed) effects on the enzyme recovery were subsequently studied by response surface methodology (RSM). Box-Bhenken Design of experiment (BBDOE) was exploited for the analysis of interactive effects of the independent variables. The optimization was done following the numerical approach focusing reduction in utility cost without compromising the endo-glucanse activity. Based on the predicted solution the validation experiments were carried out and finally 32 IU/g of endo-glucanase was recovered at room temperature, at a mixing speed of 100 rpm in 2.65 h which was very close to the predicted response. The optimization evidenced more than two times betterment in enzyme recovery than the un-optimized state. The model developed was found to be robust for process analysis. Repetitive extraction had revealed that maximum endo-glucanase recovery was required of two cycles of extraction at optimized conditions.

Biases in community structures of ammonia/ammonium-oxidizing microorganisms caused by insufficient DNA extractions from Baijiang soil revealed by comparative analysis of coastal wetland sediment and rice paddy soil

Repetitive extraction of DNAs from surface sediments of a coastal wetland in Mai Po Nature Reserve (MP) of Hong Kong and surface Baijiang soils from a rice paddy (RP) in Northeast China was conducted to compare the microbial diversity in this study. Community structures of ammonia/ammonium-oxidizing microorganisms in these samples were analyzed by PCR-DGGE technique. The diversity and abundance of ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB), and anaerobic ammonium-oxidizing (anammox) bacteria were also analyzed based on archaeal and bacterial ammonia monooxygenase subunit A encoding (amoA) and anammox bacterial 16S rRNA genes, respectively. DGGE profiles of archaeal and bacterial amoA and anammox bacterial 16S rRNA genes showed a similar pattern among all five repetitively extracted DNA fractions from both MP and RP, except the anammox bacteria in RP, indicating a more diverse anammox community retrieved in the second to the fifth fractions than the first one. Both soil and marine group AOA were detected while soil and coastal group AOB and Scalindua-anammox bacteria were dominant in MP. Soil group AOA and marine group AOB were dominant in RP, while both Scalindua and Kuenenia species were detected in RP. Pearson correlation analysis showed that the abundance of archaeal and bacterial amoA and anammox bacterial 16S rRNA genes was significantly correlated with the DNA concentrations of the five DNA fractions from MP, but not from RP (except the archaeal amoA gene). Results suggest that anammox bacteria diversity may be biased by insufficient DNA extraction of rice paddy soil samples.

Chromate reduction on humic acid derived from a peat soil – Exploration of the activated sites on HAs for chromate removal

Humic substances are a major component of soil organic matter that influence the behavior and fate of heavy metals such as Cr(VI), a toxic and carcinogenic element. In the study, a repetitive extraction technique was used to fractionate humic acids (HAs) from a peat soil into three fractions (denoted as F1, F2, and F3), and the relative importance of O-containing aromatic and aliphatic domains in humic substances for scavenging Cr(VI) was addressed at pH 1. Spectroscopic analyses indicated that the concentrations of aromatic C and O-containing functional groups decreased with a progressive extraction as follows: F1>F2>F3. Cr(VI) removal by HA proceeded slowly, but it was enhanced when light was applied due to the production of efficient reductants, such as superoxide radical and H2O2, for Cr(VI). Higher aromatic- and O-containing F1 fraction exhibited a greater efficiency for Cr(VI) reduction (with a removal rate of ca. 2.89mmolg−1 HA under illumination for 3h). 13C NMR and FTIR spectra further demonstrated that the carboxyl groups were primarily responsible for Cr(VI) reduction. This study implied the mobility and fate of Cr(VI) would be greatly inhibited in the environments containing such organic groups.

Assessment of bioburden on human and animal tissues: Part 1—Results of method development and validation studies

Recovered human and animal tissues are used extensively in surgery for wound repair and reconstruction. In preparation for the validation of chemical disinfection and radiation sterilization processes, studies were performed on the development and validation of quantitative bioburden recovery methods for human bone and soft tissue and also for porcine dermis. The use of a swab-based method was not considered due to the known poor efficiency of recovery for this technique. The "exhaustive extraction" and "inoculated product" approaches to validation of a bioburden recovery efficiency factor have inherent strengths and weaknesses; in this study, tissues were inoculated and also subjected to a series of extractions to determine if/when "exhaustion" occurred. Femoral and tibial shaft rings, iliac crest wedges, sections of Achilles tendon, a soft tissue composite sample, and porcine dermis, were inoculated at several sites with Bacillus atrophaeus spores, and then subjected to either shaking by hand, mechanical shaking, or sonication plus mechanical shaking. Each of these methods of agitation were performed in combination with three rinse (extraction) fluids: phosphate buffer (Butterfield's buffer), phosphate buffer with 0.2% polysorbate 80 (a surfactant), and water with 1% peptone and 1% polysorbate 80 (Fluid D). The highest recovery efficiencies were observed with sonication plus mechanical shaking; of the three extraction media, Fluid D gave the highest first-rinse recovery efficiency (65%) and Butterfield's buffer gave the lowest (39%). Each of the three recovery methods, however appeared to reach "exhaustion", a subsequent rinse giving less than 10% of the recovery found in the first rinse. The results demonstrated the importance of performing bioburden method development and validation studies. The method validation strategy described here, using a combination of tissue inoculation and repetitive extraction, showed the superiority of sonication plus mechanical shaking using Fluid D as the rinse medium. In addition, the use of only the exhaustive extraction approach could have resulted in the development of a methodology that consistently underestimated the bioburden present on/in recovered tissue.

Gold adsorption on the carbon surface of C/Co nanoparticles allows magnetic extraction from extremely diluted aqueous solutions

The elusive chemistry of gold has made refining from ores a difficult task and often involves handling of large volumes of water at low pH values with associated high environmental burden. As a result, the broader use of gold in environmental catalysis, organic synthesis and in electronics is still limited in spite of its most attractive chemistry. Present gold extraction suffers from metal loss in the form of gold adsorbed on active carbon particles that are washed out of the extraction process. Here, we investigate the use of magnetic carbon in the form of carbon-coated metal nanomagnets for ionic gold recovery. In contrast to acid-labile iron oxide nanoparticles, the carbon/cobalt nanomagnets resisted dissolution in acidic refining/recycling waters. Repetitive extraction runs demonstrated the possibility to recycle the magnetic reagent. A series of dilution studies showed a high affinity of the ionic gold to the carbon surfaces of the nanomagnets which enabled gold extraction down to the part per billion level (microgram per litre). Detailed investigations on the morphology of the Au-loaded nanomagnets after use suggest a mechanism based on the selective reduction of ionic gold on the C/Co surface and transfer of cobalt through the carbon shell. The resulting irreversible deposition of metallic gold correlated with the release of oxidized (ionic) cobalt into the aqueous phase.

Differential extraction of eosinophil granule proteins

Eosinophil granules contain several toxic cationic proteins that contribute to the pathophysiology of allergic diseases. These include eosinophil peroxidase, two ribonucleases, and two forms of the major basic protein (MBP). Extraction of eosinophil granules by exposure to acid solution and fractionation on Sephadex G-50 characteristically yields a distinctive profile of three discrete peaks, and these proteins are usually recovered in good quantities, except for the eosinophil major basic protein homolog (MBP2). We investigated the effect of multiple granule extractions by dilute HCl on the recovery of granule proteins. Isolated granules were repetitively extracted, up to 31 times, in 0.01 M HCl, and the extracts fractionated on Sephadex G-50. Whereas initial extracts yielded the characteristic three-peak fractionation pattern, later extracts yielded four discrete peaks. Characterization of the novel fourth peak showed that it contained MBP2. These results indicate that repetitive extraction of eosinophil granules yields an increased amount of all granule proteins, and that MBP2 can now be recovered in good quantities and in a relatively pure form.

Interactions between variable-charge soils and acidic solutions containing fluoride: an investigation using repetitive extractions

The reaction between two variable-charge soils and acidic solutions containing F was investigated with a repetitive extraction method. When added F concentration was 10 −4 mol/L, F did not markedly enhance solution pH in the whole prolonged extractions, in comparison with F-free acidic solution extractions. Most of the added F was adsorbed on soil surfaces and Al–F complexes were the dominant F species in solution. With increasing extractions, the fraction of Al–F slightly increased, arising from dissolution and/or desorption of Al. In comparison with F-free acidic solution extractions, F-induced Al dissolution did not significantly increase Al release, probably because of the modest reactivity of metal–F surface complexes at terminal sites at low F loading. The gradual decrease in Al release in the following extractions was due to the gradual depletion of readily reactive Al-containing mineral phases. In contrast to the low F loading, at an F concentration of 10 −3 mol/L, the pH was enhanced dramatically in the initial extraction and a high pH was maintained in the following extractions. In the initial extraction, the increase in negative surface charges and solution pH seemingly depressed proton-induced Al dissolution and enhanced readsorption of some positively charged Al–F complexes, resulting in low amounts of Al and F in solution. In the following several extractions, F-induced Al dissolution and desorption of Al–F complexes substantially enhanced the amounts of Al and F, and the fraction of Al–F complexes in solution. Several interconnected mechanisms such as ligand exchange, the release of OH − ions from soluble hydroxylated Al groups, desorption of Al as Al–F complexes, and F-induced breakdown of soil minerals were responsible for the alteration in pH, Al release, and the fraction of Al–F complexes in the later extractions. A molecular-level interpretation is needed in order to address the different impacts of varying F concentration levels on soil chemistry and environments.

갯장어 효소 가수분해물의 제조 및 특성

갯장어를 이용한 부가가치 높은 가공식품 개발의 일환으로 분말형태의 효소 가수분해물을 제조하고 그 특성을 살펴보았다. 분말제품의 정미성 및 소화성을 높이고 분말화를 용이하게 하기 위해 분말화하기 전에 원료윽의 효소가수분해를 검토한 결과 상업용 효소인 Flavourzyme MG^{GM}가 관능적으로 쓴맛이 적고 정미성 또한 어느 정도 향상되어 가장 적절한 효소로 판명되었고, 사용농도는 원료 단백질 함량의 <TEX>$2\%$</TEX> (w/w)로 하고, 원료에 대해 동량의 물을 가하여 마쇄한 다음 <TEX>$50^{\circ}C$</TEX>에서 6시간 처리하는 것이 좋았다. 가수분해 후 저장 중 제품의 품질 안정성에 영향을 미치는 유지를 제거하기 위해 n-hexane을 처리한 결과 효과가 있었고, 처리방법으로는 가수분해액즙에 대해 n-hexane을 4:1 (가수분해액즙:n-hexane)의 비율로 첨가하여 진탕하고 원심분리 후 상층액을 제거하는 식으로 5회 반복하는 방법이 좋았다. 그 결과 분말상태의 제품의 유지함량을 <TEX>$1\%$</TEX> 이하로 낮출 수 있었다. 분말제품의 총아미노산 조성은 원료육의 것과 비교해 거의 차이가 없었고, glutamic acid, aspartic acid, Iysine, leucine, glycine 및 arginine 둥의 아미노산이 풍부했다. 유리아미노산은 가수분해로 인해 약 3배로 증가하였고, serine, glutamic acid, alanine 및 methionine과 같은 umami를 내는 아미노산도 역시 증가하였는데 그 중에서도 소수성 아미노산인 methionine의 증가가 뚜렷했다. (약 40배). 분말제품에 있어서 양적으로 많은 유리아미노산은 소수성 아미노산인 leucine, phenylalanine, valine, alanine, isoleu-cine 등이었으며, 이중 alanine을 제외하고 모두 필수아미노산이며 이들 5종의 아미노산이 전체의 약 반 (<TEX>$48.96\%$</TEX>)을 차지하고 있는 것이 특징적이었다. 단백질 이용율은 2.35<TEX>$\~$</TEX>2.87로 원료육과 큰 차이가 없었다. 그리고 갯장어 분말제품의 수분흡수력과 지방흡수력은 각각 870.1 <TEX>$\pm$</TEX><TEX>$7.9\%$</TEX> 및 352.0<TEX>$\pm$</TEX><TEX>$5.3\%$</TEX>로 높은 편이었으며, 유화성은 50.3<TEX>$\pm$</TEX><TEX>$1.2\%$</TEX>였으나 유화안정성은 없었다. 포말성은 87.5<TEX>$\pm$</TEX><TEX>$2.5\%$</TEX>였고 용해도는 산성영역 (pH 2와 4)에서 약 83<TEX>$\~$</TEX><TEX>$84\%$</TEX>로 높았으나 pH 6이상에서는 44<TEX>$\~$</TEX><TEX>$50\%$</TEX>로 낮았다. Protein hydrolysate was prepared as a natural flavor stock from the sharp toothed eel (Muraenesox cinereus) mince using com-mercially available proteolytic enzymes, Alcalase, Neutrase, Protamex, and Flavourzyme. A 6 hr hydrolysis of mince, to which water of the equal weight of the mince was added, with <TEX>$2\%$</TEX> (w/w, protein weight) Elavourzyme at <TEX>$50^{\circ}$</TEX> yielded a hydrolysate of the highest acceptability. Removing the access lipid in liquified hydrolysate (not dehydrated) after enzyme hydrolysis, five times repetitive extraction using n-hexane (liquified hydrolysate : n-hexane=4 : 1, v/v) was effective, resulting in less than <TEX>$1\%$</TEX> lipid content of the dehydrated-hydrolysate. The amino acid composition of the hydrolysate (prepared with Flavourzyme) was similar to that of the starting material. Hydrolysis led to an increase in concentration of not only total free amino acid but also free amino acid such as serine, glutamic acid, alanine, and methionine responsible for umami taste, especially up to about 40 times for methionine. Major free amino acids in amount were leucine, phenylalanine, valine, alanine, and isoleucine and they comprised about half of the total free amino acids, Moisture adsorption, fat adsorption, emulsifying capacity, and foaming capacity of the hydrolysate were 870.1 <TEX>$\pm$</TEX> <TEX>$7.9\%$</TEX>, 352.0<TEX>$\pm$</TEX> <TEX>$5.3\%$</TEX>, 50.3 <TEX>$\pm$</TEX> <TEX>$1.2\%$</TEX>, and <TEX>$87.5\pm$</TEX> <TEX>$2.5\%$</TEX>, respectively, and solubility was 83<TEX>$\~$</TEX><TEX>$84\%$</TEX> at acid pH range of 2<TEX>$\~$</TEX>4.

Hydrogen Sulfide Gas Treatment of Cr(VI)-Contaminated Sediment Samples from a Plating-Waste Disposal SiteImplications for in-Situ Remediation

Twenty sediment samples were collected at depths ranging from 5 to 100 feet beneath a chromate-contaminated plating-waste site and analyzed for Cr(VI), total chromium, and related constituents. Three of the samples were selected for treatment with dilute hydrogen sulfide (H2S) gas to evaluate this approach as a possible in-situ remediation technique. Gas treatment was performed in soil-packed columns using 100 ppm (μL L-1) H2S mixtures, and treatment progress was assessed by monitoring the breakthrough of H2S. Evaluation of treatment efficacy included (1) water-leaching of the treated and untreated columns for 10 days, (2) repetitive extraction of treated and untreated subsamples by water, 0.01 M phosphate (pH 7) or 6 M HCl solutions, and (3) Cr K-edge X-ray absorption near-edge structure (XANES) spectroscopy of treated and untreated subsamples. Results of the water-leaching studies showed that the H2S treatment decreased Cr(VI) levels in the column effluent by 90% to nearly 100%. Repetitive extractions b...

Purification of Proteins with Aqueous Two-Phase Solvent Systems by Countercurrent Chromatography

Aqueous polymer phase systems, introduced by Albertsson1 in the 1950s, have been used for partitioning a variety of macromolecules and cell particles which include proteins,2-6 nucleic acid,7-10 cell organelles,11 viruse,12,13 bacterial cells,14,15 etc. Using these solvent systems, several different approaches have been made for performing purification of biological samples, such as single step partitioning,1 repetitive batch extraction, countercurrent distribution (CCD)16,17 and countercurrent chromatography (CCC).18-21 Among these techniques, CCC is considered to be most effective in terms of partition efficiency and separation times.

Organotin Leachates in Drinking Water from Chlorinated Poly(vinyl chloride) (CPVC) Pipe

A solid-phase extraction method, using a phenyl-bonded silica sorbent, was developed for the isolation of mono- and di-methyltin, -butyltin and -octyltin from drinking water. Recoveries averaged 92% over two tested sample weights and spiking levels. Ethyl derivatives were made by Grignard reaction for determination by gas chromatography–atomic absorption spectrometry (GC–AAS). Static and repetitive extraction studies were conducted at 24 and 65°C. Butyltins rapidly leached into drinking water kept in chlorinated poly(vinyl chloride) (CVPC) pipe samples. Monobutyltin and dibutyltin levels reached 19.8 (13.4 as Sn) and 197 (100.4 as Sn) ng g−1 respectively in water samples collected from CPVC pipe heated to 65°C. Butyltins were still leached from CPVC pipe after 20 repetitive extractions, suggesting that new CPVC water systems would contaminate water with organotins for some time after installation. © 1997 John Wiley & Sons, Ltd.