Mark Wilkins | University College London (original) (raw)

Papers by Mark Wilkins

BMJ open, Jul 27, 2016

To describe the initial outcomes following installation of a cataract surgery laser system. Natio... more To describe the initial outcomes following installation of a cataract surgery laser system. National Health Service cataract surgery day care unit in North London, UK. 158 eyes of 150 patients undergoing laser-assisted cataract surgery. Laser cataract surgery using the AMO Catalys femtosecond laser platform. intraoperative complications including anterior and posterior capsule tears. docking to the laser platform, successful treatment delivery, postoperative visual acuities. Mean case age was 67.7±10.8 years (range 29-88 years). Docking was successful in 94% (148/158 cases), and in 4% (6/148 cases) of these, the laser delivery was aborted part way during delivery due to patient movement. A total of 32 surgeons, of grades from junior trainee to consultant, performed the surgeries. Median case number per surgeon was 3 (range from 1-20). The anterior capsulotomy was complete in 99.3% of cases, there were no anterior capsule tears (0%). There were 3 cases with posterior capsule rupture ...

International Ophthalmology 33 453 454, Jul 10, 2013

Bioresource Technology, Apr 30, 2010

Hydrothermolysis pretreated switchgrass at 200 degrees C for 10min was used in a simultaneous sac... more Hydrothermolysis pretreated switchgrass at 200 degrees C for 10min was used in a simultaneous saccharification and fermentation (SSF) process using five thermotolerant yeast strains Kluyveromyces marxianus IMB 1, IMB 2, IMB 3, IMB 4, and IMB 5 at 45 degrees C and Saccharomyces cerevisiae D(5)A at 37 degrees C. SSF was carried out for 7d using 5, 10, and 15FPU/g glucan to determine the effect of decreasing cellulase loading on ethanol yield. The effect of initial pH on SSF by S. cerevisiae D(5)A was also investigated. Fermentation by K. marxianus IMB 1, IMB 2, IMB 4, and IMB 5 ceased by 72 h and fermentation by K. marxianus IMB 3 ceased by 96 h, while fermentation S. cerevisiae D(5)A continued for 7d. At 96 and 120 h, IMB 3 and S. cerevisiae D(5)A had similar ethanol yields while the other K. marxianus strains were lower at a 95% confidence level. Final ethanol yields for IMB 3, IMB 1, IMB 5 strains were similar to one another, however, ethanol yield for S. cerevisiae D(5)A (92% maximum theoretical) was greater than all of the IMB strains except IMB 3 at a 95% confidence level. Reducing enzyme loading reduced ethanol yields for both K. marxianus IMB 3 and S. cerevisiae D(5)A. Reducing buffer pH from 5.5 to 4.8 reduced ethanol yields for S. cerevisiae D(5)A. This study shows that K. marxianus IMB 3 has potential for commercial use for ethanol production from cellulose in SSF processes with further improvement of its thermotolerance.

The British journal of ophthalmology, Nov 28, 2016

To describe an optical coherence tomography angiography (OCTA) system adapted for anterior segmen... more To describe an optical coherence tomography angiography (OCTA) system adapted for anterior segment imaging, compared with indocyanine green angiography (ICGA) in eyes with corneal vascularisation. Retrospective study of subjects with corneal vascularisation secondary to microbial keratitis who had OCTA scans performed using a commercially available split-spectrum amplitude-decorrelation algorithm angiography system (AngioVue; Optovue Inc., Fremont, California, USA) and ICGA images (Spectralis; Heidelberg Engineering, Heidelberg, Germany). The agreement between OCTA and ICGA techniques in terms of area of vascularisation measured, using Bland-Altman 95% limits of agreement (LOA). We compared the area of corneal vascularisation in 64 scan images (eight eyes, four scans for each angiography technique). In our series, the overall mean area of vascularisation from the ICGA scans was 0.49±0.34 mm(2) and OCTA scans was 0.51±0.36 mm(2). We obtained substantial repeatability in terms of imag...

The British journal of ophthalmology, Jan 26, 2015

Recently, there has been an increasing clinical need for objective evaluation of corneal neovascu... more Recently, there has been an increasing clinical need for objective evaluation of corneal neovascularisation, a condition which cause significant ocular morbidity. We describe the use of a rapid, non-invasive 'en face' optical coherence tomography angiography (OCTA) system for the assessment of corneal neovascularisation. Consecutive patients with abnormal corneal neovascularisation were scanned using a commercially available AngioVue OCTA system (Optovue, Fremont, California, USA) with the split-spectrum amplitude decorrelation angiography algorithm, using an anterior segment lens adapter. Each subject had four scans in each eye by a trained operator and two independent masked assessors analysed all images. Main outcome measures were scan quality (signal strength, image quality), area of neovascularisation and repeatability of corneal vascular grade. We performed OCTA in 20 patients (11 men, 9 women, mean age 49.27±17.23 years) with abnormal corneal neovascularisation. The m...

Switchgrass was pretreated by hydrothermolysis at 200 °C for 10 min. The resulting solids had a g... more Switchgrass was pretreated by hydrothermolysis at 200 °C for 10 min. The resulting solids had a glucan content of 54%. Pretreated switchgrass containing 4 g of glucan was used in a simultaneous saccharification and fermentation (SSF) process with five thermotolerant strains of K. marxianus yeast and 60 FPU of a commercial cellulase enzyme mixture. The SSFs were performed for 7 d at 45 °C and buffered at pH 5.5. IMB 3 provided the best ethanol production results. After 72 and 96 h, IMB 3 produced 71% and 82% of theoretical maximum ethanol from glucose, respectively. None of the other strains achieved greater than 80% theoretical conversion.

Ophthalmology, 2015

To evaluate the application of an optical coherence tomography angiography (OCTA) system adapted ... more To evaluate the application of an optical coherence tomography angiography (OCTA) system adapted for the assessment of anterior segment vasculature. Cross-sectional, observational study. Consecutive subjects with normal eyes on slit-lamp clinical examination and patients with abnormal corneal neovascularization. All scans were performed using a commercially available AngioVue OCTA system (Optovue, Inc., Fremont, CA) using an anterior segment lens adapter and the split-spectrum amplitude decorrelation angiography algorithm. Each subject underwent scans from 4 quadrants (superior, inferior, nasal, and temporal) in each eye by 2 trained, independent operators. Analysis of signal strength, image quality, and reproducibility of corneal vascular measurements was performed. In our study of 20 normal subjects (10 men, 10 women; mean age, 25.3±7.8 years), we found good repeatability (κ coefficient, 0.76) for image quality score and good interobserver agreement for vasculature measurements (intraclass coefficient, 0.94). After optimization of the angiography scan protocol, vascular measurements within the regions of interest were compared in the superior versus inferior quadrants (mean vascular loops, 3.34±1.16 vs. 3.12 ± 0.90 [P = 0.768]; segment-to-loop ratio, 4.18±0.71 vs. 4.32±0.87 [P = 0.129]; fractal dimension [Df] value, 1.78±0.06 vs. 1.78±0.06 [P = 0.94]; vascular loop area, 25.9±14.5 vs. 25.9±10.7 × 10(-3) mm(2) [P = 0.21]) and nasal versus temporal quadrant (mean vascular loops, 2.89±0.98 vs. 3.57±0.99 [P < 0.001]; segment-to-loop ratio, 3.94±0.69 vs. 4.55±0.78 [P = 0.897]; Df value, 1.78±0.06 vs. 1.77±0.06 [P = 0.14]; vascular loop area, 29.7±15.7 vs. 22.1±7.1 × 10(-3) mm(2) [P = 0.38]. We then used the established OCTA scanning protocol to visualize abnormal vasculature successfully in 5 patients with various corneal pathologic features, including graft-associated neovascularization, postherpetic keratitis scarring, lipid keratopathy, and limbal stem cell deficiency. This preliminary study describes a method for acquiring OCTA images of the cornea and limbal vasculature with substantial consistency. This technique may be useful for the objective evaluation of corneal neovascularization in the future.

2002 Chicago, IL July 28-31, 2002, 2002

ABSTRACT Genetic diversity in corn (maize) has contributed to variability in corn processing char... more ABSTRACT Genetic diversity in corn (maize) has contributed to variability in corn processing characteristics. Differences in acetylated dent corn starch pasting properties and reaction efficiencies due to hybrid were assessed. Nine dent corn hybrids grown during 1998 and eight dent corn hybrids grown during 1999 were wet milled in the laboratory. Starch from each hybrid was modified using a laboratory scale acetylation procedure. NaOH consumed and reaction time were recorded for each reaction. A Rapid Visco Analyzer (RVA) was used to measure starch pasting properties. Acetyl content was measured by a spectrophotometric method, from which reaction efficiency was calculated. Differences in peak, trough, final and setback viscosities and pasting temperature were found among 1998 hybrids. Differences in trough, breakdown and final viscosities were found among 1999 hybrids.

The British journal of ophthalmology, Jan 19, 2015

Descemet membrane endothelial keratoplasty (DMEK) allows for selective replacement of damaged end... more Descemet membrane endothelial keratoplasty (DMEK) allows for selective replacement of damaged endothelial cells, using only donor Descemet's membrane with endothelium. However, early adoption by corneal surgeons has been limited (illustrated by graft registry reports: 0.7% all corneal transplants in the USA; 0.4% in Australia for 2011) due to challenges in donor preparation and surgical technique. Recently, innovative donor preparation techniques may improve availability of pre-stripped DMEK donors from eye banks. The refinement of donor insertion and manipulation techniques has also improved outcomes and reduced graft detachment rates-still, the most common postoperative complication following DMEK. Randomised studies are needed to compare clinical practices and surgeon preferences, such as intraoperative use of long-acting gas, early versus late intervention of graft detachments and postoperative steroid management. A review of current literature reveals that most publications...

Bioresource Technology, 2015

h i g h l i g h t s C. carboxidivorans, a native organism, produces butanol and hexanol from CO. ... more h i g h l i g h t s C. carboxidivorans, a native organism, produces butanol and hexanol from CO. 1.0 g/L butanol, 0.9 g/L hexanol and 3.0 g/L ethanol produced in defined medium. Technique modification reduces substrate inhibition and mass transfer limitation.

Biological Engineering Transactions, 2012

With the advancement of post-gasification processing, evaluating the effect of gas composition on... more With the advancement of post-gasification processing, evaluating the effect of gas composition on ethanol production becomes important, as the composition could be shifted prior to fermentation to optimize ethanol yield. Increasing the overall efficiency of syngas conversion to bio-ethanol involves optimizing the use of the hydrogen (H 2) component of syngas. This study focuses on the effect of different CO and H 2 concentrations in the gaseous substrate on ethanol production and hydrogenase activity using Clostridium ragsdalei. Hydrogenase activity was observed to be the least inhibited by the lowest concentrations of H 2 and CO. The maximum hydrogenase activity appeared early in the growth phase. At the lowest concentrations of CO and H 2 , hydrogenase appeared to recover activity slightly, and coincided with a depletion of acetic acid and an increase in ethanol concentrations. This phenomenon resulted in the highest concentration of ethanol observed (1.4 g L-1) at 10 days.

Biological Engineering, 2010

The bacterium "Clostridium ragsdalei" previously was identified as capable of producing ethanol f... more The bacterium "Clostridium ragsdalei" previously was identified as capable of producing ethanol from CO, CO 2 and H 2. In order to enhance the production of ethanol from these gases, three reducing agents (methyl viologen, benzyl viologen, and neutral red) were added to fermentation medium at a concentration of 0.1 mM. The medium was inoculated with "C. ragsdalei," and the headspace gas was exchanged daily with a gas mix of 20% CO, 15% CO 2 , 5% H 2 , and 60% N 2. Reducing agents were added to the culture after 91 h of cell growth. Benzyl viologen caused cell death, and no ethanol production was detected. Methyl viologen promoted ethanol production as compared to the control containing no reducing agent, while neutral red neither promoted nor detracted from ethanol production when compared to the control. Addition of 0.2 or 0.3 mM methyl viologen delayed the production of ethanol as compared with 0.1 mM methyl viologen.

Journal of Microbiological Methods, 2014

Members of the anaerobic fungi (Phylum Neocallimastigomycota) are efficient biomass degraders and... more Members of the anaerobic fungi (Phylum Neocallimastigomycota) are efficient biomass degraders and represent promising agents for fuel and chemical production from lignocellulosic biomass. Pretreatment of lignocellulosic biomass is considered an unavoidable first step in enzyme-based saccharification schemes, but its necessity in any proposed anaerobic fungi-based schemes is still unclear. Here, we evaluated the effect of hydrothermal pretreatments on the extent of corn stover and switchgrass degradation by an anaerobic fungal isolate, Orpinomyces sp. strain C1A. Using a factorial experimental design, we evaluated the effect of three different temperatures (180, 190, and 200°C) and three hold times (5, 10, and 15min). Pretreated corn stover and switchgrass were more amenable to degradation by strain C1A when compared to untreated biomass, as evident by the higher proportion of plant biomass degraded compared to untreated controls. However, when factoring in the proportion of biomass lost during the pretreatment process (ranging between 25.78 and 58.92% in corn stover and 28.34 and 38.22% in switchgrass), hydrothermolysis provided negligible or negative improvements to the extent of corn stover and switchgrass degradation by strain C1A. Product analysis demonstrated a shift towards higher ethanol and lactate production and lower acetate production associated with increase in pretreatment severity, especially in switchgrass incubations. The results are in stark contrast to the requirement of pretreatment in enzyme-based schemes for biomass saccharification, and their implications on the potential utility of anaerobic fungi in biofuel and biochemical production are discussed.

Bioresource technology, 2011

Switchgrass (Panicum virgatum) was subjected to hydrothermolysis pretreatment and then used to st... more Switchgrass (Panicum virgatum) was subjected to hydrothermolysis pretreatment and then used to study the effect of enzyme loading and temperature in a simultaneous saccharification and fermentation (SSF) with the thermotolerant yeast strain Kluyveromyces marxianus IMB3 at 8% solid loading. Various loadings of Accellerase 1500 between 0.1 and 1.1 mL g(-1) glucan were tested in SSF at 45 °C (activity of enzyme was 82.2 FPU mL(-1)). The optimum enzyme loading was 0.7 mL g(-1) glucan based on the six different enzyme loadings tested. SSFs were performed at 37, 41 and 45 °C with an enzyme loading of 0.7 mL g(-1) glucan. The highest ethanol concentration of 22.5 g L(-1) was obtained after 168 h with SSF at 45 °C, which was equivalent to 86% yield. Four different batch and fed-batch strategies were evaluated using a total solid loading of 12% (dry basis). About 32 g L(-1) ethanol was produced with the four strategies, which was equivalent to 82% yield.

2011 Louisville, Kentucky, August 7 - August 10, 2011, 2011

ABSTRACT Fermentation medium was designed for production of ethanol and acetic acid from synthesi... more ABSTRACT Fermentation medium was designed for production of ethanol and acetic acid from synthesis gas by “Clostridium ragsdalei”, also called Clostridium strain P11, which reduced the production cost by 95% compared to the standard medium. The medium was developed by serial deletion of components from the standard medium used for isolation and growth of the bacterium. Cost and purpose of individual components in the designed medium were considered to guide the revision of the medium recipe. This process resulted in the elimination of Morpholinoethanesulfonic acid (MES), a buffer used to maintain the pH near 6.0. Instead, a buffer was formed from the acetic acid produced during the fermentation and addition of bicarbonate, keeping the pH around 4.75 to enhance ethanol production. The performance of fermentation without MES, with pH control using acetate buffer was similar to that from the original rich medium. Additionally, yeast extract, an undefined growth promoter, was eliminated and trace metals for medium preparation were prepared in dilute solution without chelating agents. Fermentation without yeast extract resulted in lower growth, but comparable initial substrate uptake and production rates. Further, omission of cysteine from the medium and dependence on sulfide as nutrient sulfur source enhanced ethanol production, but did not sustain growth of strain P11. The control of pH in the designed medium and selection of appropriate sources of elemental nutrients is expected to enhance fermentation performance and further decrease cost.

ABSTRACT A thermotolerant yeast strain named Kluyveromyces marxianus IMB4 was used in a simultane... more ABSTRACT A thermotolerant yeast strain named Kluyveromyces marxianus IMB4 was used in a simultaneous saccharification and fermentation (SSF) process using Kanlow switchgrass as a feedstock. Switchgrass was pretreated using hydrothermolysis at 200 degrees C for 10 min. After pretreatment, insoluble solids were separated from the liquid prehydrolyzate by filtration and washed with deionized water to remove soluble sugars and inhibitors. Insoluble solids were then hydrolyzed using a commercial cellulase preparation and the released glucose was fermented to ethanol by K. marxianus IMB4 in an SSF process. SSF temperature was 37, 41, or 45 degrees C and pH was 4.8 or 5.5. SSF was conducted for 7 days. Results were compared with a control of Saccharomyces cerevisiae D(5)A at 37 degrees C and pH 4.8. Fermentation by IMB4 at 45 and 41 degrees C ceased after 3 and 4 days, respectively, when a pH 4.8 citrate buffer was used. Fermentation continued for all 7 days using IMB4 at 37 degrees C and the control. When pH 5.5 citrate buffer was used, fermentation ceased after 96 h using IMB4 at 45 degrees C, and ethanol yield was greater than when pH 4.8 citrate buffer was used (78% theoretical). Ethanol yield using IMB4 at 45 degrees C, pH 5.5 was greater than the control after 48, 72, and 96 h (P < 0.05).

BMJ open, Jul 27, 2016

To describe the initial outcomes following installation of a cataract surgery laser system. Natio... more To describe the initial outcomes following installation of a cataract surgery laser system. National Health Service cataract surgery day care unit in North London, UK. 158 eyes of 150 patients undergoing laser-assisted cataract surgery. Laser cataract surgery using the AMO Catalys femtosecond laser platform. intraoperative complications including anterior and posterior capsule tears. docking to the laser platform, successful treatment delivery, postoperative visual acuities. Mean case age was 67.7±10.8 years (range 29-88 years). Docking was successful in 94% (148/158 cases), and in 4% (6/148 cases) of these, the laser delivery was aborted part way during delivery due to patient movement. A total of 32 surgeons, of grades from junior trainee to consultant, performed the surgeries. Median case number per surgeon was 3 (range from 1-20). The anterior capsulotomy was complete in 99.3% of cases, there were no anterior capsule tears (0%). There were 3 cases with posterior capsule rupture ...

International Ophthalmology 33 453 454, Jul 10, 2013

Bioresource Technology, Apr 30, 2010

Hydrothermolysis pretreated switchgrass at 200 degrees C for 10min was used in a simultaneous sac... more Hydrothermolysis pretreated switchgrass at 200 degrees C for 10min was used in a simultaneous saccharification and fermentation (SSF) process using five thermotolerant yeast strains Kluyveromyces marxianus IMB 1, IMB 2, IMB 3, IMB 4, and IMB 5 at 45 degrees C and Saccharomyces cerevisiae D(5)A at 37 degrees C. SSF was carried out for 7d using 5, 10, and 15FPU/g glucan to determine the effect of decreasing cellulase loading on ethanol yield. The effect of initial pH on SSF by S. cerevisiae D(5)A was also investigated. Fermentation by K. marxianus IMB 1, IMB 2, IMB 4, and IMB 5 ceased by 72 h and fermentation by K. marxianus IMB 3 ceased by 96 h, while fermentation S. cerevisiae D(5)A continued for 7d. At 96 and 120 h, IMB 3 and S. cerevisiae D(5)A had similar ethanol yields while the other K. marxianus strains were lower at a 95% confidence level. Final ethanol yields for IMB 3, IMB 1, IMB 5 strains were similar to one another, however, ethanol yield for S. cerevisiae D(5)A (92% maximum theoretical) was greater than all of the IMB strains except IMB 3 at a 95% confidence level. Reducing enzyme loading reduced ethanol yields for both K. marxianus IMB 3 and S. cerevisiae D(5)A. Reducing buffer pH from 5.5 to 4.8 reduced ethanol yields for S. cerevisiae D(5)A. This study shows that K. marxianus IMB 3 has potential for commercial use for ethanol production from cellulose in SSF processes with further improvement of its thermotolerance.

The British journal of ophthalmology, Nov 28, 2016

To describe an optical coherence tomography angiography (OCTA) system adapted for anterior segmen... more To describe an optical coherence tomography angiography (OCTA) system adapted for anterior segment imaging, compared with indocyanine green angiography (ICGA) in eyes with corneal vascularisation. Retrospective study of subjects with corneal vascularisation secondary to microbial keratitis who had OCTA scans performed using a commercially available split-spectrum amplitude-decorrelation algorithm angiography system (AngioVue; Optovue Inc., Fremont, California, USA) and ICGA images (Spectralis; Heidelberg Engineering, Heidelberg, Germany). The agreement between OCTA and ICGA techniques in terms of area of vascularisation measured, using Bland-Altman 95% limits of agreement (LOA). We compared the area of corneal vascularisation in 64 scan images (eight eyes, four scans for each angiography technique). In our series, the overall mean area of vascularisation from the ICGA scans was 0.49±0.34 mm(2) and OCTA scans was 0.51±0.36 mm(2). We obtained substantial repeatability in terms of imag...

The British journal of ophthalmology, Jan 26, 2015

Recently, there has been an increasing clinical need for objective evaluation of corneal neovascu... more Recently, there has been an increasing clinical need for objective evaluation of corneal neovascularisation, a condition which cause significant ocular morbidity. We describe the use of a rapid, non-invasive 'en face' optical coherence tomography angiography (OCTA) system for the assessment of corneal neovascularisation. Consecutive patients with abnormal corneal neovascularisation were scanned using a commercially available AngioVue OCTA system (Optovue, Fremont, California, USA) with the split-spectrum amplitude decorrelation angiography algorithm, using an anterior segment lens adapter. Each subject had four scans in each eye by a trained operator and two independent masked assessors analysed all images. Main outcome measures were scan quality (signal strength, image quality), area of neovascularisation and repeatability of corneal vascular grade. We performed OCTA in 20 patients (11 men, 9 women, mean age 49.27±17.23 years) with abnormal corneal neovascularisation. The m...

Switchgrass was pretreated by hydrothermolysis at 200 °C for 10 min. The resulting solids had a g... more Switchgrass was pretreated by hydrothermolysis at 200 °C for 10 min. The resulting solids had a glucan content of 54%. Pretreated switchgrass containing 4 g of glucan was used in a simultaneous saccharification and fermentation (SSF) process with five thermotolerant strains of K. marxianus yeast and 60 FPU of a commercial cellulase enzyme mixture. The SSFs were performed for 7 d at 45 °C and buffered at pH 5.5. IMB 3 provided the best ethanol production results. After 72 and 96 h, IMB 3 produced 71% and 82% of theoretical maximum ethanol from glucose, respectively. None of the other strains achieved greater than 80% theoretical conversion.

Ophthalmology, 2015

To evaluate the application of an optical coherence tomography angiography (OCTA) system adapted ... more To evaluate the application of an optical coherence tomography angiography (OCTA) system adapted for the assessment of anterior segment vasculature. Cross-sectional, observational study. Consecutive subjects with normal eyes on slit-lamp clinical examination and patients with abnormal corneal neovascularization. All scans were performed using a commercially available AngioVue OCTA system (Optovue, Inc., Fremont, CA) using an anterior segment lens adapter and the split-spectrum amplitude decorrelation angiography algorithm. Each subject underwent scans from 4 quadrants (superior, inferior, nasal, and temporal) in each eye by 2 trained, independent operators. Analysis of signal strength, image quality, and reproducibility of corneal vascular measurements was performed. In our study of 20 normal subjects (10 men, 10 women; mean age, 25.3±7.8 years), we found good repeatability (κ coefficient, 0.76) for image quality score and good interobserver agreement for vasculature measurements (intraclass coefficient, 0.94). After optimization of the angiography scan protocol, vascular measurements within the regions of interest were compared in the superior versus inferior quadrants (mean vascular loops, 3.34±1.16 vs. 3.12 ± 0.90 [P = 0.768]; segment-to-loop ratio, 4.18±0.71 vs. 4.32±0.87 [P = 0.129]; fractal dimension [Df] value, 1.78±0.06 vs. 1.78±0.06 [P = 0.94]; vascular loop area, 25.9±14.5 vs. 25.9±10.7 × 10(-3) mm(2) [P = 0.21]) and nasal versus temporal quadrant (mean vascular loops, 2.89±0.98 vs. 3.57±0.99 [P < 0.001]; segment-to-loop ratio, 3.94±0.69 vs. 4.55±0.78 [P = 0.897]; Df value, 1.78±0.06 vs. 1.77±0.06 [P = 0.14]; vascular loop area, 29.7±15.7 vs. 22.1±7.1 × 10(-3) mm(2) [P = 0.38]. We then used the established OCTA scanning protocol to visualize abnormal vasculature successfully in 5 patients with various corneal pathologic features, including graft-associated neovascularization, postherpetic keratitis scarring, lipid keratopathy, and limbal stem cell deficiency. This preliminary study describes a method for acquiring OCTA images of the cornea and limbal vasculature with substantial consistency. This technique may be useful for the objective evaluation of corneal neovascularization in the future.

2002 Chicago, IL July 28-31, 2002, 2002

ABSTRACT Genetic diversity in corn (maize) has contributed to variability in corn processing char... more ABSTRACT Genetic diversity in corn (maize) has contributed to variability in corn processing characteristics. Differences in acetylated dent corn starch pasting properties and reaction efficiencies due to hybrid were assessed. Nine dent corn hybrids grown during 1998 and eight dent corn hybrids grown during 1999 were wet milled in the laboratory. Starch from each hybrid was modified using a laboratory scale acetylation procedure. NaOH consumed and reaction time were recorded for each reaction. A Rapid Visco Analyzer (RVA) was used to measure starch pasting properties. Acetyl content was measured by a spectrophotometric method, from which reaction efficiency was calculated. Differences in peak, trough, final and setback viscosities and pasting temperature were found among 1998 hybrids. Differences in trough, breakdown and final viscosities were found among 1999 hybrids.

The British journal of ophthalmology, Jan 19, 2015

Descemet membrane endothelial keratoplasty (DMEK) allows for selective replacement of damaged end... more Descemet membrane endothelial keratoplasty (DMEK) allows for selective replacement of damaged endothelial cells, using only donor Descemet's membrane with endothelium. However, early adoption by corneal surgeons has been limited (illustrated by graft registry reports: 0.7% all corneal transplants in the USA; 0.4% in Australia for 2011) due to challenges in donor preparation and surgical technique. Recently, innovative donor preparation techniques may improve availability of pre-stripped DMEK donors from eye banks. The refinement of donor insertion and manipulation techniques has also improved outcomes and reduced graft detachment rates-still, the most common postoperative complication following DMEK. Randomised studies are needed to compare clinical practices and surgeon preferences, such as intraoperative use of long-acting gas, early versus late intervention of graft detachments and postoperative steroid management. A review of current literature reveals that most publications...

Bioresource Technology, 2015

h i g h l i g h t s C. carboxidivorans, a native organism, produces butanol and hexanol from CO. ... more h i g h l i g h t s C. carboxidivorans, a native organism, produces butanol and hexanol from CO. 1.0 g/L butanol, 0.9 g/L hexanol and 3.0 g/L ethanol produced in defined medium. Technique modification reduces substrate inhibition and mass transfer limitation.

Biological Engineering Transactions, 2012

With the advancement of post-gasification processing, evaluating the effect of gas composition on... more With the advancement of post-gasification processing, evaluating the effect of gas composition on ethanol production becomes important, as the composition could be shifted prior to fermentation to optimize ethanol yield. Increasing the overall efficiency of syngas conversion to bio-ethanol involves optimizing the use of the hydrogen (H 2) component of syngas. This study focuses on the effect of different CO and H 2 concentrations in the gaseous substrate on ethanol production and hydrogenase activity using Clostridium ragsdalei. Hydrogenase activity was observed to be the least inhibited by the lowest concentrations of H 2 and CO. The maximum hydrogenase activity appeared early in the growth phase. At the lowest concentrations of CO and H 2 , hydrogenase appeared to recover activity slightly, and coincided with a depletion of acetic acid and an increase in ethanol concentrations. This phenomenon resulted in the highest concentration of ethanol observed (1.4 g L-1) at 10 days.

Biological Engineering, 2010

The bacterium "Clostridium ragsdalei" previously was identified as capable of producing ethanol f... more The bacterium "Clostridium ragsdalei" previously was identified as capable of producing ethanol from CO, CO 2 and H 2. In order to enhance the production of ethanol from these gases, three reducing agents (methyl viologen, benzyl viologen, and neutral red) were added to fermentation medium at a concentration of 0.1 mM. The medium was inoculated with "C. ragsdalei," and the headspace gas was exchanged daily with a gas mix of 20% CO, 15% CO 2 , 5% H 2 , and 60% N 2. Reducing agents were added to the culture after 91 h of cell growth. Benzyl viologen caused cell death, and no ethanol production was detected. Methyl viologen promoted ethanol production as compared to the control containing no reducing agent, while neutral red neither promoted nor detracted from ethanol production when compared to the control. Addition of 0.2 or 0.3 mM methyl viologen delayed the production of ethanol as compared with 0.1 mM methyl viologen.

Journal of Microbiological Methods, 2014

Members of the anaerobic fungi (Phylum Neocallimastigomycota) are efficient biomass degraders and... more Members of the anaerobic fungi (Phylum Neocallimastigomycota) are efficient biomass degraders and represent promising agents for fuel and chemical production from lignocellulosic biomass. Pretreatment of lignocellulosic biomass is considered an unavoidable first step in enzyme-based saccharification schemes, but its necessity in any proposed anaerobic fungi-based schemes is still unclear. Here, we evaluated the effect of hydrothermal pretreatments on the extent of corn stover and switchgrass degradation by an anaerobic fungal isolate, Orpinomyces sp. strain C1A. Using a factorial experimental design, we evaluated the effect of three different temperatures (180, 190, and 200°C) and three hold times (5, 10, and 15min). Pretreated corn stover and switchgrass were more amenable to degradation by strain C1A when compared to untreated biomass, as evident by the higher proportion of plant biomass degraded compared to untreated controls. However, when factoring in the proportion of biomass lost during the pretreatment process (ranging between 25.78 and 58.92% in corn stover and 28.34 and 38.22% in switchgrass), hydrothermolysis provided negligible or negative improvements to the extent of corn stover and switchgrass degradation by strain C1A. Product analysis demonstrated a shift towards higher ethanol and lactate production and lower acetate production associated with increase in pretreatment severity, especially in switchgrass incubations. The results are in stark contrast to the requirement of pretreatment in enzyme-based schemes for biomass saccharification, and their implications on the potential utility of anaerobic fungi in biofuel and biochemical production are discussed.

Bioresource technology, 2011

Switchgrass (Panicum virgatum) was subjected to hydrothermolysis pretreatment and then used to st... more Switchgrass (Panicum virgatum) was subjected to hydrothermolysis pretreatment and then used to study the effect of enzyme loading and temperature in a simultaneous saccharification and fermentation (SSF) with the thermotolerant yeast strain Kluyveromyces marxianus IMB3 at 8% solid loading. Various loadings of Accellerase 1500 between 0.1 and 1.1 mL g(-1) glucan were tested in SSF at 45 °C (activity of enzyme was 82.2 FPU mL(-1)). The optimum enzyme loading was 0.7 mL g(-1) glucan based on the six different enzyme loadings tested. SSFs were performed at 37, 41 and 45 °C with an enzyme loading of 0.7 mL g(-1) glucan. The highest ethanol concentration of 22.5 g L(-1) was obtained after 168 h with SSF at 45 °C, which was equivalent to 86% yield. Four different batch and fed-batch strategies were evaluated using a total solid loading of 12% (dry basis). About 32 g L(-1) ethanol was produced with the four strategies, which was equivalent to 82% yield.

2011 Louisville, Kentucky, August 7 - August 10, 2011, 2011

ABSTRACT Fermentation medium was designed for production of ethanol and acetic acid from synthesi... more ABSTRACT Fermentation medium was designed for production of ethanol and acetic acid from synthesis gas by “Clostridium ragsdalei”, also called Clostridium strain P11, which reduced the production cost by 95% compared to the standard medium. The medium was developed by serial deletion of components from the standard medium used for isolation and growth of the bacterium. Cost and purpose of individual components in the designed medium were considered to guide the revision of the medium recipe. This process resulted in the elimination of Morpholinoethanesulfonic acid (MES), a buffer used to maintain the pH near 6.0. Instead, a buffer was formed from the acetic acid produced during the fermentation and addition of bicarbonate, keeping the pH around 4.75 to enhance ethanol production. The performance of fermentation without MES, with pH control using acetate buffer was similar to that from the original rich medium. Additionally, yeast extract, an undefined growth promoter, was eliminated and trace metals for medium preparation were prepared in dilute solution without chelating agents. Fermentation without yeast extract resulted in lower growth, but comparable initial substrate uptake and production rates. Further, omission of cysteine from the medium and dependence on sulfide as nutrient sulfur source enhanced ethanol production, but did not sustain growth of strain P11. The control of pH in the designed medium and selection of appropriate sources of elemental nutrients is expected to enhance fermentation performance and further decrease cost.

ABSTRACT A thermotolerant yeast strain named Kluyveromyces marxianus IMB4 was used in a simultane... more ABSTRACT A thermotolerant yeast strain named Kluyveromyces marxianus IMB4 was used in a simultaneous saccharification and fermentation (SSF) process using Kanlow switchgrass as a feedstock. Switchgrass was pretreated using hydrothermolysis at 200 degrees C for 10 min. After pretreatment, insoluble solids were separated from the liquid prehydrolyzate by filtration and washed with deionized water to remove soluble sugars and inhibitors. Insoluble solids were then hydrolyzed using a commercial cellulase preparation and the released glucose was fermented to ethanol by K. marxianus IMB4 in an SSF process. SSF temperature was 37, 41, or 45 degrees C and pH was 4.8 or 5.5. SSF was conducted for 7 days. Results were compared with a control of Saccharomyces cerevisiae D(5)A at 37 degrees C and pH 4.8. Fermentation by IMB4 at 45 and 41 degrees C ceased after 3 and 4 days, respectively, when a pH 4.8 citrate buffer was used. Fermentation continued for all 7 days using IMB4 at 37 degrees C and the control. When pH 5.5 citrate buffer was used, fermentation ceased after 96 h using IMB4 at 45 degrees C, and ethanol yield was greater than when pH 4.8 citrate buffer was used (78% theoretical). Ethanol yield using IMB4 at 45 degrees C, pH 5.5 was greater than the control after 48, 72, and 96 h (P < 0.05).