Gas-particle partitioning of semivolatile organic compounds (SOCs) on mixtures of aerosols in a smog chamber

The partitioning behavior of a set of diverse SOCs on two and three component mixtures of aerosols from different sources was studied using smog chamber experimental data. A set of SOCs of different compound types was introduced into a system containing a mixture of aerosols from two or more sources. Gas and particle samples were taken using a filter-filter-denuder sampling system, and a partitioning coefficient Kp was estimated using Kp = Cp/(CgTSP). Particle size distributions were measured using a differential mobility analyzer and a light scattering detector. Gas and particle samples were analyzed using GCMS. The aerosol composition in the chamber was tracked chemically using a combination of signature compounds and the organic matter mass fraction (f(om)) of the individual aerosol sources. The physical nature of the aerosol mixture in the chamber was determined using particle size distributions, and an aggregate Kp was estimated from theoretically calculated Kp on the individual sources. Model fits for Kp showed that when the mixture involved primary sources of aerosol, the aggregate Kp of the mixture could be successfully modeled as an external mixture of the Kp on the individual aerosols. There were significant differences observed for some SOCs between modeling the system as an external and as an internal mixture. However, when one of the aerosol sources was secondary, the aggregate model Kp required incorporation of the secondary aerosol products on the preexisting aerosol for adequate model fits. Modeling such a system as an external mixture grossly overpredicted the Kp of alkanes in the mixture. Indirect evidence of heterogeneous, acid-catalyzed reactions in the particle phase was also seen, leading to a significant increase in the polarity of the resulting aerosol mix and a resulting decrease in the observed Kp of alkanes in the chamber. The model was partly consistent with this decrease but could not completely explain the reduction in Kp because of insufficient knowledge of the secondary organic aerosol composition.     

Glass transition temperature-structural studies of tungstate tellurite glasses

Raman, IR and DSC studies have been carried on the (100 − x)TeO₂–xWO₃ (TW) glasses with 10 ≤ x ≤ 40 mol%. The Raman, IR spectra of these samples show that glass network consists of [TeO₃]/[TeO₃₊₁], [TeO₄], [WO₄] and [WO₆] groups as basic structural units. The W ion coordination state changes from 4 to 6 when WO₃ concentration increases beyond 30 mol%. Addition of WO₃ oxide to the TW glasses increases the amount of lower coordination of [TeO₃]/[TeO₃₊₁] units and decreases the higher coordination [TeO₄] units, Te–O–Te chains. From DSC thermogram, thermal properties such as the glass transition temperature (T_g), onset crystallization (T_o) of the glass systems were calculated. The compositional variation of glass transition temperature (T_g) is found to linear with an increase in WO₃ content.     

Acrylamide content in fried chips prepared from irradiated and non-irradiated stored potatoes

The content of reducing sugars and asparagine, responsible for the formation of acrylamide, was determined in eight Indian potato varieties. Among these, Kufri chipsona-2 and Kufri lavkar showed the lowest level of reducing sugar (680.68 ± 56.50 mg/kg) and asparagine (2074.36 ± 122.27 mg/kg), respectively. The acrylamide content in potato chips prepared from Kufri chipsona-2, the variety that is used commercially in India for making potato chips was also the lowest. Irradiation of this variety of potatoes at the sprout inhibition dose of 60 Gy and subsequent storage for six months showed a 10.7% lower content of reducing sugars at both 14 and 4 °C. The acrylamide content was 8.41% and 6.95% lower in chips from irradiated potatoes stored at 14 and 4 °C than the corresponding non-irradiated controls. The colour of the chips was also better in irradiated potatoes as judged from the L∗ and a∗ values.     

Bioconjugation of MOF-5 for molecular sensing

Zn-BDC (BDC = 1,4-benzenedicarboxylate acid) or more commonly known as metal organic framework (MOF-5) was synthesized via chemical stirring method and bioconjugated with anti-bovine serum albumin (anti-BSA) through pendent group. The pendent group of organic linker on surface of MOF-5 has been activated via EDC (1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide) based simple organic reaction and then bioconjugation of anti-BSA was achieved. Bioconjugation of anti-BSA on to MOF-5 has been used to study the interaction with BSA based on their fluorescence properties. Fluorescent microscopy revealed successful interaction of anti-BSA with BSA onto MOF-5 surface. In addition, BSA conjugated MOF-5 showed no loss of enantioselectivity and structure stability. Photoluminescence quenching of the developed probe was demonstrated to observe the presence of BSA.     

A novel distributed architecture of large-scale multimedia storage system using autonomous object-based storage devices

In a large-scale multimedia storage system (LMSS) where the user requests for different multimedia objects may have different demands, placement and replication of the objects is an important factor, as it may result in an imbalance in loading across the system. Since replica management and load balancing is a crucial issue in multimedia systems, normally this problem is handled by centralized servers, e.g., metadata servers (MDS) in distributed file systems. Each object-based storage device (OSD) responds to the requests coming from the centralized servers independently and has no communication with other OSDs among the system. In this paper, we design a novel distributed architecture of LMSS, in which the OSDs have some kind of intelligences and can cooperate to achieve a high performance. Such an OSD, named as autonomous object-based storage device (AOSD), can replicate the objects to and balance the requests among other AOSDs, and handle fail-over and recovery autonomously. In the proposed architecture, we move the request balancing from centralized MDS to AOSDs and make the system more scalable, flexible, and robust. Based on the proposed architecture, we propose two different object replication and load balancing algorithms, named as “Minimum Average Waiting Time” (MAWT) and “One of the Best Two Choices” (OBTC), respectively. We validate the performance of the algorithms via rigorous simulations with respect to several influencing factors. Our findings conclusively demonstrate that the proposed architecture minimizes the average waiting time and at the same time carries out load balancing across servers.     

Bucket brigade algorithm for hierarchical censored production rule-based system

A bucket brigade algorithm for production rule-based system is reviewed and its suitability to variable precision logic-based systems is explored. A modified version of the bucket brigade suitable for a censored production rule-based system and hierarchical censored production rule-based system is proposed. The standard bucket brigade algorithm is modified by appending rule status to each rule in addition to its strength. The rule status (unknown, correct, not correct, doubtful, or confirmed) helps in deciding the strategy for bid payment. The proposed algorithm incorporates strategy to resolve the problem of weakening of correct rules which are activated by incorrect rules. The problem is resolved by continuously weakening such incorrect rules, thereby not allowing them to enter the conflict set. Examples are included to illustrate various ideas involved in the proposed algorithm. © 1996 John Wiley & Sons, Inc.     

Galactosyl oligosaccharide purification by ethanol precipitation

Galactosyl oligosaccharides (GOS) are prebiotics commonly manufactured by β-galactosidase conversion of lactose, producing a mixture containing GOS, lactose, glucose and galactose. Enrichment of GOS in this mixture adds value to the product. This study aimed to determine whether the addition of ethanol to aqueous saccharide solutions could be used to selectively precipitate and enrich GOS from a reaction mixture. High concentrations of ethanol (>70% v/v) were required to induce precipitation. The total saccharide concentration was a significant variable, with higher GOS enrichment occurring at lower total saccharide concentrations. Varying the temperature between 10 and 40 °C had less impact than had changes in the concentration of saccharide or ethanol. GOS was enriched 2.3 (±0.1) fold in the precipitate formed in a solution of 90% (v/v) ethanol with 28 g/L of total saccharide at 40 °C. Performing two such precipitations sequentially reduced the monosaccharides from 48% (w/w) of the total saccharides to 4% (w/w). GOS precipitation has potential for industrial application as it is simple in operation and offers levels of purification similar to those by other techniques.     

Crosstalk between Delta Opioid Receptor and Nerve Growth Factor Signaling Modulates Neuroprotection and Differentiation in Rodent Cell Models

Both opioid signaling and neurotrophic factor signaling have played an important role in neuroprotection and differentiation in the nervous system. Little is known about whether the crosstalk between these two signaling pathways will affect neuroprotection and differentiation. Previously, we found that nerve growth factor (NGF) could induce expression of the delta opioid receptor gene (Oprd1, dor), mainly through PI3K/Akt/NF-κB signaling in PC12h cells. In this study, using two NGF-responsive rodent cell model systems, PC12h cells and F11 cells, we found the delta opioid neuropeptide [d-Ala², d-Leu⁵] enkephalin (DADLE)-mediated neuroprotective effect could be blocked by pharmacological reagents: the delta opioid antagonist naltrindole, PI3K inhibitor {"type":"entrez-nucleotide","attrs":{"text":"LY294002","term_id":"1257998346","term_text":"LY294002"}}LY294002, MAPK inhibitor PD98059, and Trk inhibitor K252a, respectively. Western blot analysis revealed that DADLE activated both the PI3K/Akt and MAPK pathways in the two cell lines. siRNA Oprd1 gene knockdown experiment showed that the upregulation of NGF mRNA level was inhibited with concomitant inhibition of the survival effects of DADLE in the both cell models. siRNA Oprd1 gene knockdown also attenuated the DADLE-mediated neurite outgrowth in PC12h cells as well as phosphorylation of MAPK and Akt in PC12h and F11 cells, respectively. These data together strongly suggest that delta opioid peptide DADLE acts through the NGF-induced functional G protein-coupled Oprd1 to provide its neuroprotective and differentiating effects at least in part by regulating survival and differentiating MAPK and PI3K/Akt signaling pathways in NGF-responsive rodent neuronal cells.     

Dietary Source of Stearidonic Acid Promotes Higher Muscle DHA Concentrations than Linolenic Acid in Hybrid Striped Bass

Rapid expansion of aquacultural production is placing increasing demand on fish oil supplies and intensified the search for alternative lipid sources. Many of the potential alternative sources contain low concentrations of long chain n-3 fatty acids and the conversion of dietary linolenic acid to longer chain highly unsaturated fatty acids is a relatively inefficient process in some species. A 6-week study was conducted to compare tissue fatty acid (FA) concentrations in hybrid striped bass fed either 18:3n-3 (α-linolenic acid; ALA) or 18:4n-3 (stearidonic acid; SDA). Hybrid striped bass were fed either a control diet containing fish oil, or diets containing ALA or SDA at three different levels (0.5, 1 and 2% of the diet). There were no significant differences in whole animal responses between fish fed ALA or SDA. Liver and muscle concentrations of ALA and SDA were responsive to dosages fed. However, only 22:6n-3 concentrations in muscle were significantly affected by dietary source of 18 carbon precursors. Muscle 22:6n-3 concentrations were significantly higher in fish fed SDA compared to fish fed ALA. Based on these data, it appears that feeding SDA can increase long chain n-3 fatty acid concentrations in fish muscle.