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A passive pH control system to process high strength (COD ∼ 20,000 mg l−1) acidic wastewater without alkali addition was developed. The low-energy wastewater treatment system consisted of a packed bed up-flow anaerobic reactor followed by an aerobic trickling filter, both of which used biochar as the biofilm support media. The passive pH control process relied on controlled recycle of the effluent leaving the anaerobic stage to adjust the pH of the acidic feedstock. The anaerobic reactor was able to achieve steady state reductions in total chemical oxygen demand (TCODred) above 91% and the combined system (anaerobic-aerobic) achieved COD reductions above 97% without alkali addition. Methane production was 0.311 m3 per kg COD reduced. The system was also able to produce an effluent that met EPA regulations in terms of BOD5 and TSS, possessed a near neutral pH, and was highly nitrified.

PURPOSE To describe anatomical relationships of retinal neovascular complexes (NVCs) and the posterior vitreous in proliferative diabetic retinopathy using spectral domain optical coherence tomography. METHODS Cross-sectional study. Neovascular complexes were imaged using spectral domain optical coherence tomography in 51 eyes of 37 patients. The relationship of NVCs to the posterior vitreous cortex and posterior vitreous spaces, such as the premacular bursa, prevascular vitreous fissures, and perimacular cisterns, was analyzed. RESULTS In the 77 NVCs evaluated, 61 (79%) had grown along the outer surface of the posterior hyaloid face, and vitreoschisis was present in 37 (48%). The "wolf's jaw" configuration was present in 9% and resulted from NVC arising from the arcades and proliferating along the posterior hyaloid face. By contrast, NVCs that invaded the bursa originated from smaller venous tributaries more distant from the arcades. The premacular bursa and prevascular vitreous fissure/perimacular cistern were invaded infrequently, respectively, in 15% and 38% (P = 0.137). CONCLUSION Tomographic analysis of diabetic NVCs showed that most NVCs arise and grow along the posterior hyaloid face and that vitreoschisis is more prevalent than what has been found in ultrasound studies. The wolf's jaw configuration does not seem to result from the invasion of the bursa, as previously suggested.

The use of ionic liquid (IL)/polar covalent molecule (PCM) cosolvent mixtures is a significant new pathway to extract and separate oils and other high-value components from algae and other bio-oil-bearing biomasses. In this work, light-scattering and steady-state fluorescence polarization techniques were utilized to characterize cosolvent behavior at the micro- and macroscales, and their measurements correlated to lipid extraction yields. In addition, molecular dynamics simulations were employed to probe the fundamental interactions between IL and PCMs in solution. Both experimental and computational (radial distribution functions and clustering analysis) data confirmed the increased aggregation between IL cations and anions with increasing methanol concentration. For the 1-ethyl-3-methylimidazolium methyl sulfate/methanol (MeOH) system, this ion aggregation appears to correlate with experimentally observed decreases in the maximum lipid extraction yields for MeOH concentrations above 80 vol %. At these c...

The fate of oil-seed biomass protein has been tracked through all steps of a multi-phase extraction process using an ionic liquid based co-solvent system previously demonstrated to extract bio-oil and phorbol esters and to recover fermentable sugars from Jatropha oil seed. These analyses, however, did not address the fate of biomass protein. This work demonstrated that the majority of protein (∼86%) tracked with the biomass with the balance lost to co-solvent (∼12%) and methanol (∼2%) washes. A significant portion of the ionic liquid remained with the treated biomass and required aggressive methanol washes to recover. A system analysis showed a net-positive energy balance and thus the potential of this system to produce both bio-oil and protein-rich toxin-free biomass. While these results further support Jatropha as an oil seed crop, the additional costs of solvent recovery will need to be addressed if commercialization is to be realized.

PurposeTo investigate the progression characteristics of ellipsoid zone (EZ) loss in eyes with macular telangiectasia type 2 (MacTel) as reflected by area and linear measurements, and their relevance for visual acuity.MethodsParticipants were selected from the MacTel Study cohort. Linear and area measurements of EZ loss were performed in Spectral-Domain Optical Coherence Tomograph (SD-OCT) volume scans. Progression characteristics and correlations between linear and area measurements were analysed using linear mixed effects models.ResultsA total of 134 eyes of 70 patients were included (85 eyes with follow-up, mean 4.7years, range: 1.4-8years). Ellipsoid zone (EZ) loss significantly progressed at a mean annual increment of 0.057mm2 (p=0.005). The progression rate was non-linear and interacted significantly with initial EZ lesion size indicating an exponential growth before reaching a plateau. There was a strong heterogeneity in area sizes between fellow eyes. EZ break length had a significant linear effect on EZ break area (b=1.06, p&nbsp

The efficacy of biofilm based anaerobic-aerobic treatment to reduce caffeine, carbamazepine, and three estrogens (Estrone (E1), 17β-estradiol (E2), and 17α-ethynylestradiol (EE2)), as well as E. coli (CN-13) and F+ specific coliphage (MS2), from synthetic wastewater was investigated. Results showed no observable reduction of carbamazepine by either anaerobic or aerobic biofilms over a dosing period of 51-days followed by an additional 23 days of observation. Caffeine, by contrast, was reduced by 11.09% in the upflow anaerobic packed bed biofilm reactor (UAnPBBR) and by 91.90% in the aerobic trickling filter biofilm reactor (TF). Estrone (E1) and 17β-estradiol (E2) showed minimal reduction in the UAnPBBR but 99.67% reduction in the TF, while EE2 was reduced 1.62% in the AnPBBR and 20.36% in the TF. On average, a 3-log reduction of E. coli (CN-13) and a 1-log reduction of F+ specific coliphage (MS2) concentration was observed across the overall reactor system.

The development of microbial biofilm community in biochar packed anaerobic digesters was explored during start up at demonstration scale on high strength grease trap waste wastewater. Total and soluble chemical oxygen demand reduction reached 68% and 69%, respectively, after just fifty nine days at an HRT of 1.8 days. Methane head space gas compositions averaged across all reactors exceeded 60% and total methane production rates approached the theoretical maximum per kilogram of chemical oxygen demand reduced. Aggressive consumption of volatile organic acids correlated linearly with an increase in pH from 5.86 in the mixing reactor to a value of 7.61 in the final effluent. Both soluble and total phosphorous and total nitrogen were relatively unaffected by the treatment. Active methanogenic microbial biofilm communities possessing high proportions of methanogens were established despite the presence of feed wastewater streams possessing significantly different populations of planktonic bacteria. In sum, these results indicate that biochar alone can support the rapid development of robust well balanced methanogenic microbial biofilms that effectively minimize the impact of influent microbial communities on the reactor microbial biofilm communities.

This work evaluates the ability of an ionic liquid-methanol cosolvent system to extract lipids and recycle fermentable sugars recovered from oil-bearing Rhodosporidium toruloides grown in batch culture on defined media using glucose and xylose as carbon sources. Growth on the recycled mixed carbon substrate was successful with glucose consumed before xylose and overall cell mass to lipid yields (YP/X ) between 57% and 61% (w/w relative to whole dried cell mass) achieved. Enzymatic hydrolysis of the delipified carbohydrate fraction recovered approximately 9%-11% (w/w) of the whole dried cell mass as fermentable sugars, which were successfully recycled as carbon sources without further purification. In total, up to 70% (w/w) of the whole dried cell mass was recovered as lipids and fermentable sugars and the substrate to lipid yields (YP/S ) was increased from 0.12 to 0.16 g lipid/g carbohydrate consumed, highlighting the promise of this approach to process lipid bearing cell biomass.

The co-production of biodiesel and methane gas from grease trap waste (GTW) was evaluated and compared against theoretical predictions of methane production from sole anaerobic digestion of GTW. The GTW was first processed into two separate phases comprised of fats, oil, and grease (FOG) and high strength wastewater (GTW wastewater). The GTW wastewater was then anaerobically digested in biochar packed up-flow column reactors to produce methane gas and a low-strength wastewater effluent while the FOG phase was set aside for conversion into biodiesel. Anaerobic digestion efficiencies that yielded chemical oxygen demand (COD) reductions up to 95% and methane headspace concentrations between 60 and 80% were achieved along with FOG to biodiesel conversion efficiencies of 90%. Methane production yields (m3 per kg COD reduced) achieved theoretical maximums with near total depletion of the volatile organic acids. High resolution images of biochar samples confirmed extensive coverage with thick biofilm communities. Microbial analysis revealed broad spectrum populations of anaerobic bacteria that ferment organic substrates to produce acetate, ethanol, and hydrogen as major end products as well as archaeal populations that produce methane gas. Energy calculations validated the co-production of biodiesel and methane gas from GTW as a competitive option relative to its co-digestion with sewage sludge.

This work developed and used performance indicators to quantitatively cross-compare over 82 liquid phase anaerobic digestion treatment processes/technologies. Results showed that anaerobic membrane reactors generally performed best in terms of reduction of total chemical oxygen demand, while upflow anaerobic sludge blanket reactors exceled with respect to the volumetric reduction of total chemical oxygen demand. Although packed bed and moving bed reactors showed large variations in reduction of total chemical oxygen demand, they generally produced higher methane yields (i.e. >0.25 m3 methane produced per kg total chemical oxygen demand reduced). While high performance was desired across all performance indicators, it was generally not achieved by any specific reactor type. The performance indicators were also used to directly cross-compare performance of two separate reactors treating identical wastewater streams. Result showed that both systems demonstrated good performance relative to the literature but neither was dominant in head-to-head comparison.

To describe the clinical characteristics and progression of patients with multifocal choroiditis lesions who had minimal or no evidence of anterior uveitis and/or vitritis.Retrospective, observational, single-center consecutive case series. Clinical histories, examination, and multimodal imaging findings were analyzed.Sixty-five eyes of 41 patients were identified. The mean age at diagnosis was 38.4 years (median, 35 years; range, 15-81 years), and 70.7% of the patients were women. Involvement was bilateral in 21 patients (51.2%) at presentation. The 60-month bilateral event-free survival was 75.0% (95% confidence interval, 49.8-91.2%). The mean visual acuity was 20/46 (median, 20/25; range, 20/20 to count fingers at 2 feet) at presentation and 20/42 (median, 20/25; range, 20/20-5/400) at the last recorded visit. The 60-month "20/50 or worse" event-free survival was 100%. Between the first presentation and final follow-up (a mean duration of 92.6 months; range, 0-343 months), 46.7% of the eyes developed new or larger chorioretinal spots and 32.6% developed new or recurrent choroidal neovascularization. The 60-month choroidal neovascularization event-free survival was 68.1% (95% confidence interval, 39.2-85.4%).Patients with multifocal choroiditis lesions, but with minimal or no anterior uveitis or vitritis, tended to be young women. Approximately half of the patients presented with bilateral involvement, which is less than has been reported in most case series of multifocal choroiditis with panuveitis. One quarter of all unilaterally affected patients will develop bilateral involvement by 60 months.

This work evaluates the applicability of an ionic liquid–methanol co-solvent system to extract phorbol esters from jatropha biomass. The extracted phorbol esters readily solubilized into the co-solvent due to a shared amphiphilic nature. Methyl sulfate anion had superior performance relative to acetate anion, extracting and solubilizing higher quantities of phorbol esters. Compared to traditional methods which only extract phorbol esters, the co-solvent system simultaneously extracted and separated the bio-oil to its own separate immiscible phase and with no appreciable loss of protein – the majority of protein remaining with the biomass and only a small residual amount (∼1 mg/ml) solubilizing into the co-solvent. The optimum co-solvent concentration for simultaneous extraction of phorbol esters and bio-oil was determined to be 30 wt% IL and 70 wt% methanol. With respect to the extracted kernel biomass, the high proportion of protein (68–70%) and low phorbol esters (0.15 mg/g kernel) content suggested a high suitability as an animal feed.

An electrogenic biofilm was developed on a macroporous chitosan-carbon nanotube (CHIT-CNT) electrode under constant poised potential (-0.25V versus Ag/AgCl reference electrode) and flow through conditions utilizing the effluent of an anaerobic digester as both the inoculant and substrate for the electrogenic biofilm. After 125 days of inoculation the bioelectrode demonstrated an open circuit potential of -0.62V and a current density of 9.43μAcm(-3) (at -0.25V). Scanning electron microscopy images indicate thorough surface coverage of the biofilm with a high density of bacterial nanowires physically connecting bacteria to bacteria and bacteria to carbon nanotube (electrode surface) suggesting the nanowires are electrically conductive. DGGE was used to identify the major bacterial and archaeal populations.

Enzyme kinetics is the study of the chemical reactions that are catalyzed by enzymes, with a focus on their reaction rates. The study of an enzyme's kinetics considers the various stages of activity, reveals the catalytic mechanism of the enzyme, correlates its value to assay conditions, and describes how a drug or a poison might inhibit the enzyme. Victor Henri initially reported that enzyme reactions were initiated by a bond between the enzyme and the substrate. By 1910, Michaelis and Menten had advanced this work by studying the kinetics of the enzyme saccharase, which catalyzes the hydrolysis of sucrose into glucose and fructose. They published their analysis, and ever since, the Michaelis-Menten equation has been used as the standard to describe the kinetics of many enzymes. Unfortunately, soluble enzymes must generally be immobilized to be reused for long times in industrial reactors. In addition, other critical enzyme properties have to be improved like stability, activity, inhibition by reaction products, selectivity toward nonnatural substrates. Immobilization is by far the chosen process to achieve these goals.Although the Michaelis-Menten approach has been regularly adopted for the analysis of immobilized enzyme activity, its applicability to the immobilized state is limited by the barriers the immobilization matrix places upon the measurement of compounds that are used to model enzyme kinetics. That being said, the estimated value of the Michaelis-Menten coefficients (e.g., V(max), K(M)) can be used to evaluate effects of immobilization on enzyme activity in the immobilized state when applied in a controlled manner. In this review, enzyme activity and kinetics are discussed in the context of the immobilized state, and a few novel protocols are presented that address some of the unique constraints imposed by the immobilization barrier.

This paper conducts a comparative assessment of the environmental impacts of three methods of treating primary clarifier effluent in wastewater treatment plants (WWTPs) through life cycle assessment methodology. The three technologies, activated sludge (AS), high rate anaerobic-aerobic digestion (HRAAD), and trickling filter (TF), were assessed for treatment of wastewater possessing average values of biochemical oxygen demand and total suspended solids of 90 mg L−1 and 70 mg L−1, respectively. The operational requirements to process the municipal wastewater to effluent that meets USEPA regulations have been calculated. The data for the AS system were collected from the East Honolulu WWTP (Hawaii, USA) while data for the HRAAD system were collected from a demonstration-scale system at the same plant. The data for the TF system were estimated from published literature. Two different assessment methods have been used in this study: IMPACT 2002+ and TRACI 2. The results show that TF had the smallest environmental impacts and that AS had the largest, while HRAAD was in between the two but with much reduced impacts compared with AS. Additionally, the study shows that lower sludge production is the greatest advantage of HRAAD for reducing environmental impacts compared with AS.

Biasing and threshold adjustments are crucial for the correct operation and sensitivity of 3T based pixel detectors. The latest generation of pixel detectors detectors designed at the University of Hawaii (UH) have adjustable triggering thresholds by including on chip 8-bit R-2R Digital to Analog Converters (DAC). The DAC is the first designed at UH to be manufactured in a 0.20 μm SOI CMOS technology. The DAC has additionally been fabricated in a 0.13 μm CMOS technology. The inclusion of such structure allows comparison between fabrication runs as well as fabrication technologies. Simulations and preliminary results are included, as well as comparisons between fabrication technologies.

Microbial fuel cell research is a relatively new and fast growing field of interdisciplinary effort that has drawn scientists from several disparate disciplines. Consequently, establishing a “common language” regarding the “means and ways” of experimental preparation, data collection and characterization to obtain accurate and comparable figures of merit (describing microbial fuel cell performance) has proven difficult. We present a methodology for comprehensive engineering analysis from inoculation through batch, fed-batch and finally continuous flow operation, and detail how a modified stack cell design complements this. More, our cell is able to operate near the thermodynamic maximum potential for oxidation of lactate.

A hybrid lactate/air biofuel cell has been created using a microbial anode with Shewanella MR1 integrated into a chitosan–carbon nanotube porous matrix and a DET-based laccase air-breathing cathode. Open circuit potentials of 1 V and power densities of 26 W/m3 are reported. A stable 5-day galvanostatic polarization shows a loss of only 4% of potential.

The ability of an ionic liquid–alcohol co-solvent to facilitate the acid-catalyzed (HCl) direct transesterification of intercellular lipids to fatty acid methyl esters (FAMEs) was investigated. The FAME product, which autopartitions to a separate immiscible phase, was easily recovered. With the exception of theChlorella microalgae, the conversion from triglycerides to FAMEs was nearly complete (100%) for all biomass sources investigated and the gravimetric yields of FAME product were found to be similar to those in the absence of acid catalyst. As the co-solvent system used in this study was highly polar, and thus immiscible with the FAME product, the action of the ionic liquid molecules was presumed to provide both hydrophobic regions or channels that provided some association with the alkyl side chains on the lipid, as well as energy to push the FAME product out of phase with the co-solvent, and into its own separate and immiscible phase self, as the ionic liquid anions and cations continued to self ass...

The applicability of ionic liquid-polar covalent molecule co-solvent systems to extract bio-oils from biomass is evaluated. In our approach the extracted lipids are auto-partitioned to a separate immiscible phase for ease of harvesting. We propose that the action of the polar covalent molecule is largely to disrupt the cell wall and to improve the efficiency at which the lipid is extracted from the biomass. As ionic liquid solutions are both amphiphilic and characterized by strong “self-associating” ionic bonding between the cations and anions, we propose that the action of the ionic liquid is to facilitate the transfer of the lipids to the surface interface where they auto partition into a self-associating and separate phase. The potential of the co-solvent system to co-extract protein is also noted.

Hydrophobically modified chitosan has been proposed for enzyme immobilization and stabilization at bioelectrodes in biofuel cells. In this paper, we analytically evaluate the attributes of employing hydrophobically modified chitosan molded into high porosity scaffolds to improve enzyme activity and mass transport of malate dehydrogenase bioelectrodes. Results suggest that the hydrophobically modified chitosan can alter catalytic activity of malate dehydrogenase and that scaffold structure improves power density over chitosan thin films. Fluorescence measurements are also presented that correlate the improved activity to alterations in the amphiphilic nature of the chemical microenvironment (immediately surrounding the enzyme) that the modified chitosan affords. Commentary is also given on how mass transport through the chitosan matrix can be improved in order to achieve higher power densities.

In this work, the uronic acids assay was evaluated for its potential to function as a bioassay to screen for antagonistic activity against the production of microbial biofilm exopolysaccharide (EPS). The assay was first applied to biofilms produced in the presence of two universal disinfectants (sodium hypochlorite and sodium dodecyl sulfate) known to inhibit microbial growth and biofilm formation. The performance of the assay was then characterized through statistical assessment of threshold concentrations for disinfection efficiency and consistency relative to values reported in the literature. The assay was then evaluated for its utility in screening for enzymatic or chemical inhibitors of biofilm formation (eg glycosidases, halogenated furanones, and semi-crude fractions extracted from minimally fouled marine plants) and its ability to distinguish between true anti-biofilm activity and simple disinfection. Activity was characterized as (i) no effect, (ii) a true positive effect (ie increased biofilm EPS), (iii) anti-bacterial activity (ie decreased biofilm EPS and analogous decrease in planktonic growth), and (iv) anti-biofilm EPS activity (ie decreased biofilm EPS, without analogous decrease in planktonic growth). Results demonstrate that the uronic acids assay can augment existing biofilm characterization methods by providing a quantitative measure of biofilm EPS.

A wide variety of terrestrial biomass feed stocks have been identified as suitable candidates for fractionation and conversion into biofuels. In particular, microalgae have been promoted as a future source of transportation fuels primarily because of their stated potential to produce up to 10 times more oil per acre than traditional biofuel crops. Their ability to grow relatively fast, be harvested on a daily basis, and grown in earthen ponds or closed photobioreactors that occupy marginal or poor crop lands using salt or brackish water, are often referenced. When these attractive traits are coupled with the potential to concomitantly harvest valuable co‐products such as biopolymers, proteins, and animal feeds, one can see why microalgae are often touted as biotechnology's “green gold”. The development of large‐scale microalgae farms, however, has been slowed by limitations in downstream processing technology. For example, traditional methods to dewater, extract, and recover bio‐oil from oil‐seeds possess...

Chitosan, a biopolymer extracted from chitin, was deacetylated by treatment with 45% NaOH followed by autoclaving at 121oC for a period of 20 minutes. The deacetylated chitosan was then hydrophobically modified via reductive amination with sodium cyanoborohydride and butanal. Glucose dehydrogenase was then co-cast with each polymer on glassy carbon rotating disk electrodes and analysis of mass transfer was executed. Amperometric concentration studies were also carried out to determine catalytic activity of the glucose dehydrogenase enzyme system. The diffusion coefficient governing transport through the air dried film was measured to be 1.42×10-7 cm2/s and 1.08×10-7 cm2/s for butyl modified chitosan and butyl modified deacetylated chitosan, respectively.

First feed production continues to be a major barrier to the cultivation of many fish species. Although copepod nauplii are a suitable food, consistency and high production have been difficult. Temporal changes in production in batch cultures of the calanoid copepod, Bestiolina similis, were investigated to develop management strategies for the use of copepod nauplii as a live food. Population abundances and female egg production rates were measured, and recruitment and mortality rates were calculated. Relative expression levels of a molecular biomarker for stress, heat shock protein hsp70, were determined using real-time quantitative polymerase chain reaction. The population cycle included a period of rapid increase in abundances, followed by a steep decline and a period of stable but low population densities. Initially, egg production exceeded 25 eggs per female per day and low mortality rates prevailed. The population decline was preceded by upregulation of hsp70 and followed by an 80–90% decline in female fecundity and an increase in mortality rates. Egg production rates remained below four eggs per female per day even after new generations of females reached adulthood. The predictable population cycle provides opportunities to coordinate nauplius production rates with first feed needs of fish larvae.

In this work we use the steady state and time-resolved fluorescence of free and enzyme-bound fluorophores to characterize the binding capacity of both unmodified and hydrophobically modified chitosan polymers. Additionally, fluorescence emission is used to qualitatively characterize the extent to which hydrophobic modification of the chitosan polymer affects the relative polarity of the resultant amphiphillic micelles. In total, these results are used to describe how fluorescence techniques can be used to characterize the chemical microenvironment provided by immobilization polymers such as chitosan. Commentary is also given on how this information can be correlated to enzyme activity and spatial distribution during the immobilization processes.

Chitosan is a deacetylated form of the polysaccharide chitin. Over the last decade, researchers have employed reductive amination to hydrophobically modify chitosan to induce a micellar structure. These micellar polymers have been used for a variety of purposes including drug delivery and enzyme immobilization and stabilization. However, commercial sources of chitosan vary in their degree of deacetylation and there remains a paucity of information regarding how this can impact the modified polymer’s functionality for enzyme immobilization. This paper, therefore, evaluates the effect that the degree of deacetylation has on the hydrophobic modification of medium molecular weight chitosan via reductive amination with long chain aldehydes and the resulting changes in enzyme activity after the immobilization of glucose oxidase in the micellar polymeric structure. The chitosan was deacetylated to differing degrees via autoclaving in 40–45% NaOH solutions and characterized using NMR, viscosity measurements, and differential scan calorimetry. Results suggest that a high degree of deacetylation provides optimal enzyme immobilization properties (i.e. high activity), but that the deacetylation method begins to significantly decrease the polymer molecular weight after a 20 min autoclave treatment, which negatively affects immobilized enzyme activity.

Chitosan scaffolds were fabricated by application of thermally induced phase separation from aqueous solutions of unmodified chitosan and hydrophobically modified chitosan polymer. The final pore structure, in terms of diameter and geometry, were correlated to freezing temperature and freezing time for both the unmodified and hydrophobically modified chitosan polymer. Results showed that the resulting pore structure is strongly dependent upon the freezing temperature and less dependant upon the freezing time. For scaffolds produced from unmodified chitosan, the pore size decreased as expected with decreasing freezing temperature from −5 °C to −10 °C. However, an inconsistency in this trend was observed as the freezing temperature was decreased to −20 °C. Combined analysis of pore size distribution and average pore diameter suggested that the freezing process was mainly mass transfer dominated at −5 °C and −10 °C, but principally heat transfer dominated at −20 °C. In comparison, the scaffolds produced from hydrophobically modified chitosan (butyl-chitosan) followed the expected trend of decreasing mean pore diameter with decreased freezing temperatures throughout the entire temperature range. The scaffolds produced from the unmodified chitosan were more stable and rigid, and possessed average pore diameters that were generally smaller than those fabricated from the hydrophobically modified chitosan. The generally larger pores in the butyl-modified chitosan scaffolds might be explained by increased phase separation rates due to the introduced hydrophobicity of the chitosan polymer. Among the scaffolds fabricated from the butyl-modified chitosan, those produced at −20 °C yielded the most uniform pore structure, the smallest average pore diameters, and the least temporal broadening of pore size distribution.

In this work, confocal laser scanning microscopy was used to study the spatial distribution of malate dehydrogenase immobilized within three-dimensional macroporous chitosan scaffolds. The scaffolds were fabricated from solutions of native and hydrophobically modified chitosan polymer through the process of thermally induced phase separation. The hydrophobically modified chitosan is proposed to possess amphiphilic micelles into which the enzyme can be encapsulated and retained. To test this theory, we applied the immobilization procedure of Klotzbach and co-workers [J. Membr. Sci. 2006, 282 (1-2), 276-283] to solutions of fluorophore-tagged malate dehydrogenase in the presence of native and hydrophobically modified chitosan polymer and then tracked the distribution of enzymes in the resulting scaffolds using fluorescent microscopy. Results suggest that the modified chitosan does encapsulate the enzyme with a significant degree of retention and with altered distribution patterns, suggesting that hydrophobic modification of the chitosan polymer backbone does create amphiphilic regions that are capable of physically encapsulating and retaining enzymes. Commentary is also given on how this information can be correlated to enzyme activity and spatial distribution during immobilization processes.

Multiwalled carbon nanotubes (MWCNTs) were used as doping material for three-dimensional chitosan scaffolds to develop a highly conductive, porous, and biocompatible composite material. The porous and interconnected structures were formed by the process of thermally induced phase separation followed by freeze-drying applied to an aqueous solution of 1 wt % chitosan acetic acid. The porosity was characterized to be 97% by both mercury intrusion porosimetry measurements and SEM image analysis. When MWCNTs were used as a filler to introduce conductive pathways throughout the chitosan skeleton, the solubilizing hydrophobic and hydrophilic properties of chitosan established stable polymer/MWCNT solutions that yielded a homogeneous distribution of nanotubes throughout the final composite matrix. A percolation theory threshold of approximately 2.5 wt % MWCNTs was determined by measurement of the conductivity as a function of chitosan/MWCNT ratios. The powder resistivity of completely compressed scaffolds also was measured and was found to be similar for all MWCNT concentrations (0.7-0.15 Omega cm powder resistivity for MWCNTs of 0.8-5 wt %) and almost five times lower than the 20 k Omega cm value found for pure chitosan scaffolds.

This paper investigates the utility of ‘cross–lab’ comparative analysis of electrocatalytic electrode performance using standardized modular stack cells and test protocols. Using poly(methylene green)-modified glassy carbon electrodes as the model system, we characterized electrode fabrication and performance with respect to the catalytic oxidation of NADH at neutral pH and low overpotential. Three sets of experiments were duplicated across four independent laboratories and the experimental results from each set were analyzed and compared in terms of key electroanalytical parameters. Statistical analyses were performed at three distinct levels: 1) the standard deviation among repetitive cycles within an experiment; 2) the standard deviation among repetitive experiments in the same laboratory, and 3) the standard deviation among experiments performed across all four laboratories. Using predefined criteria of ‘reproducibility’ for each level, most parameters were found to be statistically reproducible at most levels. When a particular parameter was found to be irreproducible in a given level, commentary is given on how that information can be used diagnose what chemical/physical aspects of the process were uncontrolled or poorly understood and therefore candidates for future research. This exercise, which is presented as a ‘proof–of-principle’ step towards the concept of standardizing electrocatalytic evaluation, illustrates the importance of executing electrochemical characterization protocols across several labs and using fixed geometry and dimensions, system configuration, and applied electrochemical conditions. Future work is under way to extend these principles to systems with fluid flow.

Purpose To describe an unusual case of diffuse circumpapillary choroidal melanoma masquerading as atypical central serous chorioretinopathy, and to describe fluorescein angiographic and optical coherence tomography characteristics of this diffuse choroidal melanoma. Design Interventional case report. Methods A 46-year-old human immunodeficiency virus-positive man presented with an 11-month history of decreased vision and the absence of an elevated choroidal lesion. The patient failed to return for follow-up. Results Thirteen months after his initial presentation, circumpapillary diffuse choroidal melanoma was diagnosed. The patient underwent enucleation. No extrascleral extension was present. Conclusions Imaging characteristics on fluorescein angiography or optical coherence tomography may be of diagnostic value to aid the ophthalmologist in earlier detection of diffuse choroidal melanomas.

The thermal conversion of sewage sludge to biochar offers a promising alternative use for a hazardous waste material with potential benefits to agricultural productivity and soil quality. Three short-term greenhouse experiments were conducted to evaluate the effect of corn cob (CC) and sewage sludge (SS) biochars, with their anaerobically treated counterparts, on soil properties and plant growth in an infertile Oxisol. The anaerobically treated SS biochar showed the greatest concentration of bioavailable essential nutrients, but treatment only resulted in increased yields for the SS biochar in the first crop in the absence of added fertilizer. Both CC and SS biochars in combination with fertilizer doubled plant growth compared to the control in the first crop cycle, produced no significant effect in the second cycle, and more than tripled plant growth for the SS biochars in the third cycle. High ash content with high nutrient contributions (especially P) and a persistent liming effect explain the benefits of the SS biochars to plant growth. The SS biochar showed promise in mitigating the negative effects of soil Mn toxicity. Sewage sludge biochars reduced Cd bioavailability and had no significant effect on the bioavailability of other potentially toxic metals compared to the control.

The market for lipids is a broad and expanding one that includes nutraceuticals, cosmetics, and precursors for fuels such as biodiesel. However, it can also suffer periodic fluctuations in demand, which can undermine product revenues. This chapter describes the various processes of lipid extraction from biomass sources such as food waste, animal waste, oil seeds, and unicellular microorganisms.

What would it be like if you could recharge your cell phone battery instantly by pouring your soft drink into it? Such applications may be a long way off, but the U.S. Air Force Office of Scientific Research is investing in such a future now.

Enzyme-based biofuel cells possess several positive attributes for energy conversion, including renewable catalysts, flexibility of fuels (including renewables), and the ability to operate at room temperature. However, enzyme-based biofuel cells remain limited by short lifetimes, low power densities and inefficient oxidation of fuels. Recent advances in biofuel cell technology have addressed these deficiencies and include methods to increase lifetime and environmental stability.

Background: Bevacizumab, a humanized monoclonal antibody to vascular endothelial growth factor (VEGF), has been given via intravitreal injection as an off-label therapy for both neovascular age-related macular degeneration and for macular edema secondary to retinal vascular disease. The authors describe three patients with macular edema secondary to retinal venous occlusion whose edema initially responded to intravitreal bevacizumab but subsequently recurred in excess of that observed before treatment. Methods: This is a retrospective case series of three patients with macular edema secondary to retinal vein occlusion treated with intravitreal bevacizumab. Results: In all three patients, the rebound retinal edema observed was more pronounced than that present before treatment. Conclusion: These cases suggest a potential limitation of using relatively short-acting VEGF antagonists in retinal vascular disease of a chronic nature. Frequent repeated injections may be required to prevent a rebound effect with no clearly defined endpoint. Until the long-term safety of multiple injections of these agents is established, the authors recommend caution in using this treatment strategy.

Nile Red, a dye that fluoresces at defined wavelengths depending upon the polarity of the surrounding medium, has been proposed to determine the neutral lipid content of microalgal cells. Herein we communicate modifications to this technique that facilitate its use as a high-throughput screening technology, as well as improving its accuracy and versatility.

We retrospectively evaluated the effectiveness of intravitreal triamcinolone in treating 19 eyes with macular edema related to branch retinal vein occlusion (BRVO). Eyes with nonischemic BRVO respond more favorably than those with ischemic BRVO. A single injection of intravitreal triamcinolone led to elevated intraocular pressure in 3 of 19 eyes (16%). Half of phakic eyes had progression of cataract. Retreatment may be necessary.

Aim: To review the outcomes of eyes with neovascular age-related macular degeneration (AMD) treated with photodynamic therapy (PDT) with verteporfin and intravitreal triamcinolone acetonide injection. Materials and Methods: We retrospectively reviewed the outcomes of consecutive eyes with neovascular AMD that received an intravitreal triamcinolone injection within 1 week of their first PDT and had at least 6 months of follow-up. Eyes were retreated with PDT at 3-month intervals if angiographic leakage was present. Results: Twenty-six eyes from 24 patients were identified. The mean visual acuity at baseline was 20/118 (median 20/112). The mean visual acuity decreased to 20/138 at 9 months (P = 0.24, n = 15) and to 20/174 at 12 months (P = 0.23, n = 8). The change in visual acuity from baseline was not statistically significant at any time point. The mean central foveal thickness by OCT measured 342 µm at baseline and decreased to 296 µm at 12 months (P = 0.31). Sixty-two per cent of eyes required no additional PDT at 12 months. Nineteen per cent of 26 eyes had a rise in intraocular pressure that was controlled with topical medication alone. Conclusion: Photodynamic therapy with verteporfin combined with intravitreal triamcinolone injection in the treatment of neovascular AMD may be superior to PDT alone by decreasing visual loss and reducing the number or retreatments. Key words: Choroidal neovascularisation, Macular degeneration, Photodynamic therapy, Triamcinolone, Verteporfin

The marine photoheterotroph Erythrobacter longus Strain NJ3Y was grown in continuous culture under variable light:dark (L:D) regimes of 24:0, 12:12 and 0:24 h to examine the influence of photoperiod on pigmentation and metabolic efficiency. Average carbon mass balances for each light regime closed to within 5 %, giving confidence in the measured variables as well as calculations of physiological parameters. Significant differences in photosynthetic pigmentation were observed for the experimental light treatments, with highest and lowest pigment concentrations measured in the 0:24 and 24:0 h L:D regimes, respectively, indicating that the photosynthetic pigments of E. longus Strain NJ3Y are preferentially synthesized in the dark. These differences are consistent with the strategy that photosynthetic pigments are produced during periods of darkness, for use in energy harvesting during subsequent light periods. In contrast, concentrations of the photoprotective pigment caloxanthin sulfate were highest for cells grown under a 12:12 h L:D cycle, indicating that this carotenoid is synthesized in the light and the dark. It is concluded that the 12:12 h L:D regime provides the maximum opportunity for E. longus Strain NJ3Y to derive a metabolic advantage from light availability (i.e. by enabling it to both synthesize and utilize its light harvesting apparatus). The corresponding carbon-specific glucose uptake rate was similar to 30% higher than that measured for the 0:24 and 24:0 h L:D regimes. It is hypothesized that light-stimulated rates of dissolved organic carbon uptake by bacteriochlorophyll a containing bacteria confer a slight competitive advantage over bacteria that lack this photosynthetic machinery. Lowest glucose-specific biomass yields (Y-x/s, g dry cell wt g(-1) glucose) were observed for the 12:12 h L:D treatment, suggesting that under the culture conditions used in this study, photosynthesis does not contribute significantly to the growth of E. longus Strain NJ3Y.

Enzyme catalyzed biofuel cells have been proposed as an alternative to transition metal catalysts for power generation as they oxidize alcohols at relatively low overpotential without the production of detrimental carbon monoxide, and are capable of operation at lower temperatures [Palmore GT, Bertschy H, Bergens SH, Whitesides GM. A methanol/dioxygen biofuel cell that uses NAD()-dependent dehydrogenase as catalysts: application of an electro-enzymatic method to regenerate nicotinamide adenine dinucleotide at low overpotentials. J Electroanal Chem 1998;443:155-61]. Additionally, the immobilization procedure prevents internal leakage or cross-contamination of electron mediators. However, full realization of the membrane-less biofuel cell as a power source requires a three-dimensional boundary structure which balances the overall effective surface area against porosity, thus ensuring the maximum number of catalyst sites are available without suffering the blockage of fuel transport, which occurs if the pore size is too small. In this work, a simple and in situ method using a simplified diffusion model is presented to estimate the total activity immobilized enzyme in the absence of mass transfer effects. The method, which also calculates a combined mass transfer parameter including an effective diffusion coefficient, models the reactant concentration at the enzyme surface using bulk concentrations which then can be measured in situ by spectrophotometric detection or ex situ by HPLC analysis. The method was then applied to evaluate two methods of alcohol dehydrogenase electrode fabrication: direct adsorption to carbon felt and entrapment within the conductive polymer polypyrrole. Results showed that direct adsorption provided 26 times the activity versus the method of direct entrapment and better mass transfer characteristics. Correlation of these results to scanning electron micrographs suggested that the polypyrrole entrapment method lacked the expected diffusive pathways and most likely expelled enzyme during growth of the film. (c) 2005 Elsevier Inc. All rights reserved.

To describe the short-term anatomical and visual acuity responses after intravitreal injection of bevacizumab (Avastin, Genentech) in patients with choroidal neovascularization (CNV) secondary to age-related macular degeneration (AMD).We conducted a retrospective study of patients with CNV secondary to AMD who were treated with intravitreal injection of bevacizumab (1.25 mg) during a 3-month period. Patients underwent best-corrected Snellen visual acuity testing, optical coherence tomography, and ophthalmoscopic examination at baseline and follow-up visits.There were 266 consecutive eyes of 266 patients who received injections, and follow-up information was available for 251 (94.4%). The mean age of the patients was 80.3 years, the mean baseline visual acuity was 20/184, and 175 (69.7%) had inadequate response to alternate methods of treatment. At the 1-month follow-up (data available for 244 patients), the mean visual acuity was 20/137 (P0.001 as compared with baseline), and 74 (30.3%) of patients had improvement in visual acuity as defined by a halving of the visual angle. At the 2-month follow-up (data available for 222 patients), the mean visual acuity was 20/122 (P0.001), and 78 (31.1%) of patients had visual improvement. At the 3-month follow-up (data available for 141 patients), the mean visual acuity was 20/109 (P0.001), and 54 (38.3%) of patients had visual acuity improvement. The mean central macular thickness at baseline was 340 mum and decreased to a mean of 247 microm at month 1 (P0.001) and 213 microm at month 3 (P0.001). At 1 month, two patients had mild vitritis, as did one patient at 2 months, who had a history of recurrent uveitis. No endophthalmitis, increased intraocular pressure, retinal tear, or retinal detachment occurred. The risk for thromboembolic disorders did not seem to be different than reported previously in studies concerning macular degeneration.There were no apparent short-term safety concerns for intravitreal bevacizumab injection for CNV. Treated eyes had a significant decrease in macular thickness and improvement in visual acuity. The follow-up was too short to make any specific treatment recommendations, but the favorable short-term results suggest further study is needed.