Process optimization by decoupled control of key microbial populations: distribution of activity and abundance of polyphosphate-accumulating organisms and nitrifying populations in a full-scale IFAS-EBPR plant

This study investigated the abundance and distribution of key functional microbial populations and their activities in a full-scale integrated fixed film activated sludge-enhanced biological phosphorus removal (IFAS-EBPR) process. Polyphosphate accumulating organisms (PAOs) including Accumulibacter and EBPR activities were predominately associated with the mixed liquor (>90%) whereas nitrifying populations and nitrification activity resided mostly (>70%) on the carrier media. Ammonia oxidizer bacteria (AOB) were members of the Nitrosomonas europaea/eutropha/halophila and the Nitrosomonas oligotropha lineages, while nitrite oxidizer bacteria (NOB) belonged to the Nitrospira genus. Addition of the carrier media in the hybrid activated sludge system increased the nitrification capacity and stability; this effect was much greater in the first IFAS stage than in the second one where the residual ammonia concentration becomes limiting. Our results show that IFAS-EBPR systems enable decoupling of solid residence time (SRT) control for nitrifiers and PAOs that require or prefer conflicting SRT values (e.g. >15 days required for nitrifiers and <5 days preferred for PAOs). Allowing the slow-growing nitrifiers to attach to the carrier media and the faster-growing phosphorus (P)-removing organisms (and other heterotrophs, e.g. denitrifiers) to be in the suspended mixed liquor (ML), the EBPR-IFAS system facilitates separate SRT controls and overall optimization for both N and P removal processes.     

Advances in data processing for open-path Fourier transform infrared spectrometry of greenhouse gases

The automated quantification of three greenhouse gases, ammonia, methane, and nitrous oxide, in the vicinity of a large dairy farm by open-path Fourier transform infrared (OP/FT-IR) spectrometry at intervals of 5 min is demonstrated. Spectral pretreatment, including the automated detection and correction of the effect of interrupting the infrared beam, is by a moving object, and the automated correction for the nonlinear detector response is applied to the measured interferograms. Two ways of obtaining quantitative data from OP/FT-IR data are described. The first, which is installed in a recently acquired commercial OP/FT-IR spectrometer, is based on classical least-squares (CLS) regression, and the second is based on partial least-squares (PLS) regression. It is shown that CLS regression only gives accurate results if the absorption features of the analytes are located in very short spectral intervals where lines due to atmospheric water vapor are absent or very weak; of the three analytes examined, only ammonia fell into this category. On the other hand, PLS regression works allowed what appeared to be accurate results to be obtained for all three analytes.     

Comparing the effect on protein stability of methionine oxidation versus mutagenesis: steps toward engineering oxidative resistance in proteins

The biological activity of some proteins is known to be sensitiveto oxidative damage caused by a variety of oxidants. The modelprotein staphylococcal nuclease was used to explore the effecton protein structural stability of oxidizing methionine to thesulfoxide form. These effects were compared with the effectsof substituting methionines with isoleucine and leucine, a potentialstrategy for stabilizing proteins against oxidative damage.Wild-type nuclease and various mutants were oxidized with hydrogenperoxide. Stabilities of both oxidized and unoxidized proteinswere determined by guanidine hydrochloride denaturation. Oxidationdestabilized the wild-type protein by over 4 kcal/mol. Thislarge loss of stability supports the idea that in some casesloss of biological activity is linked to disruption of the proteinnative state. Comparison of mutant protein's stability lossesupon oxidation showed that methionines 65 and 98 had a muchgreater destabilizing effect when oxidized than methionines26 or 32. While substitution of methionine 98 carried as greatan energetic penalty as oxidation, substitution at position65 was less disruptive than oxidation. Thus a simple substitutionmutagenesis strategy to protect a protein against oxidativedestabilization is practical for some methionine residues.     

Formation of antibiotic,biodegradable polymers by processing with Irgasan DP300R (triclosan) and its inclusion compound with β-cyclodextrin

The inclusion compound (IC) between the FDA-approved antibacterial Irgasan DP300 (Trichlosan), and β-cyclodextrin (CD) has been formed. When the Irgasan–β-CD–IC is embedded in biodegradeable/bioabsorbable films of poly(ϵ-caprolactone) (PCL) at low levels (a few wt %), they are rendered resistant to the growth of E. coli bacteria. When these same PCL films embedded with Irgasan–β-CD–IC are used as the adhesive for laminating cotton fabrics, we observe the resulting cotton laminates to also be resistant to the growth of E. coli bacteria. These results hold promise for the fabrication of bacteria-resistant polymer films and fibers, as well as antibacterial fabrics, by means of simple melt processing with Irgasan–β-CD–IC. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 300–309, 2001     

Maternal contributions to sensory experience in the fetal and newborn rat (Rattus norvegicus).

Using videographic analyses, maternal contributions to the sensory environment of the perinatal rat were identified and quantified by analyzing, from the offspring's perspective, the dam's activities during gestation, labor, and delivery. The observations indicate that pregnant females remain highly active during the final week of gestation, as compared with nonpregnant control animals. Exploratory movements, feeding, drinking, self-grooming, and other activities of the rat dam pitch, turn, accelerate, and expose fetuses to mechanical pressures. During parturition uterine contractions and maternal licking and handling provide vigorous tactile and vestibular stimuli to pups. Newly born pups are exposed to intense thermal stimulation, cooling rapidly to the temperature of the postnatal environment. Results suggest that fetal and newborn rats are exposed during development to a broad range of maternally produced stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

InP-based AllnAs/GaAs<Subscript>0.51</Subscript>Sb<Subscript>0.49</Subscript>/GaInAs single heterojunction bipolar transistor for high-speed and RF wireless applications

The InP-based AlInAs-GaAsSb-GaInAs heterojunction bipolar transistors (HBTs) have been grown by solid-source molecular-beam epitaxy (SSMBE). Since the AlInAs-GaAsSb heterojunction has a type-II (staggered) band lineup, the conduction-band discontinuity is negligible at 300 K (10 meV). Thus, the turn-on voltage is significantly lower than that of an AlInAs-GaInAs HBT even without compositional grading of the emitter-base junction. A self-aligned process was used to fabricate large area devices. The measured turn-on voltage and collector-emitter offset were 0.36 V and 0.23 V, respectively, with a DC current gain of approximately 25 and ideality factors of η_C = 1.01 and η_B = 1.1 at J_C = 10 kA/cm² collector-current density.     

Microscale spectrophotometric methods for quantification of functional groups in oxidized organic aerosol

Spectrophotometric methods developed previously to quantify the major functional groups present in oxidized organic aerosol were modified for use with sample masses typical of those collected from ambient air. In these methods, carbonyl, hydroxyl, carboxyl, and ester groups are reacted with derivatizing agents that are specific to each functional group to form strongly light absorbing derivatives, a colored peroxide solution is formed through redox chemistry, and nitrates have an inherently strong absorbance. As described here, improved detection limits are made possible by measuring absorbance using a spectrophotometer that requires only a few microliters of solution for analysis, instead of the five milliliter volume required previously when using a standard cuvette. Use of this so-called NanoPhotometer allows comparable absorbances to be obtained with much less mass by concentrating samples by more than two orders of magnitude relative to previous methods. Detection limits are approximately 0.03, 0.02, 0.3, 1, 1, and 0.07 nmoles for carbonyl, hydroxyl, carboxyl, ester, peroxide, and nitrate groups, which correspond to approximately 0.8, 0.6, 10, 40, 50, and 5 ng of each functional group. In practice, depending on the composition of functional groups, the mass required for complete analysis of moderately oxidized organic aerosol is ～10–100 µg. The new microscale methods were shown to provide good linearity, precision, and accuracy by comparing results from the analysis of standards and aerosol formed from reaction of α-pinene and O₃ with results obtained using the previously developed macroscale methods. The evaluation demonstrates that the microscale methods can be used to quantify these six functional groups at low organic aerosol mass concentrations.

Copyright © 2016 American Association for Aerosol Research     

Results of the study of chemical-, vacuum drying- and plasma-pretreatment of coconut (Cocos nucifera) lumber sawdust for the adsorption of methyl red in water solution

The study to be presented is motivated by the need of certain industries to implement a cost-effective method of cleaning up wastewater from industrial processes, for example the clean-up of dye-tainted wastewater from textile mills. Biomass by-products, for a long time, have been the popular choice for the role of clean-up agents for certain applications but sometimes the efficiency for adsorption of the targeted waste material is not promising and thus the need for pre-treatment of the biomass material. This work will present the results of a study using three methods of pre-treating coconut (Cocos nucifera) lumber sawdust for the adsorption of methyl red dye in water solution, namely; (1) chemical processing using formaldehyde treatment and sulfuric acid treatment, (2) vacuum drying, and (3) plasma treatment. The vacuum drying and plasma treatment utilized a hexapole-magnetized microwave plasma device that uses a 2.45 GHz microwave source. The results showed that there is a dramatic increase in the dye removal efficiency (% dye removal) after the treatment of the coconut sawdust. The highest recorded % dye removal is as follows: formaldehyde treatment (20%), sulfuric acid treatment (40%), vacuum dried (62%), hydrogen plasma (65%), oxygen plasma (67%) and argon plasma (70%). It was also shown that the % dye removal is dependent on the initial dye concentration, adsorbent dosage, contact time, and pH. The adsorption results of this study were fitted with Freundlich and Langmuir isotherm models but the data are better described by the Freundlich isotherm model as compared to Langmuir. From the results of the study, it is concluded that the methods of vacuum drying and plasma pre-treatment are more effective alternative to chemical processing of the coconut lumber sawdust in the adsorption of dye in wastewater.     

A spatially and chemically defined platform for the uniform growth of human pluripotent stem cells

We report the design of a chemically defined platform engineered for the culture of human pluripotent stem cells (hPSCs) that supports the long-term maintenance of self-renewing hPSC populations in a more uniform manner than standard culture systems. Microcontact printing (μCP) of alkanethiol self-assembled monolayers (SAMs) was used to spatially direct hPSC adherence. This technique not only establishes control over hPSC colony size and shape but also preserves genetic stability and provides unprecedented uniformity in the pluripotency of hPSC populations that is quantitatively assessed in the present study.     

Synthesis, characterization, and direct intracellular imaging of ultrasmall and uniform glutathione-coated gold nanoparticles

Gold nanoparticles (AuNPs) with core sizes below 2 nm and compact ligand shells constitute versatile platforms for the development of novel reagents in nanomedicine. Due to their ultrasmall size, these AuNPs are especially attractive in applications requiring delivery to crowded intracellular spaces in the cytosol and nucleus. For eventual use in vivo, ultrasmall AuNPs should ideally be monodisperse, since small variations in size may affect how they interact with cells and how they behave in the body. Here we report the synthesis of ultrasmall, uniform 144-atom AuNPs protected by p-mercaptobenzoic acid followed by ligand exchange with glutathione (GSH). Quantitative scanning transmission electron microscopy (STEM) reveals that the resulting GSH-coated nanoparticles (Au(GSH)) have a uniform mass distribution with cores that contain 134 gold atoms on average. Particle size dispersity is analyzed by analytical ultracentrifugation, giving a narrow distribution of apparent hydrodynamic diameter of 4.0 ± 0.6 nm. To evaluate the nanoparticles' intracellular fate, the cell-penetrating peptide TAT is attached noncovalently to Au(GSH), which is confirmed by fluorescence quenching and isothermal titration calorimetry. HeLa cells are then incubated with both Au(GSH) and the Au(GSH)-TAT complex, and imaged without silver enhancement of the AuNPs in unstained thin sections by STEM. This imaging approach enables unbiased detection and quantification of individual ultrasmall nanoparticles and aggregates in the cytoplasm and nucleus of the cells.