13 research outputs found
Assessment of the surgical outcomes of esotropia in pediatric subjects with high accommodative convergence/accommodation ratio: A clinical assessment
Background: Treating subjects with a high AC/A ratio and with esotropia is a challenging and complex procedure, often associated with increased near deviation which may lead to various outcomes following the surgery. Aims: The present study was conducted to assess outcomes following surgery in children with esotropia who were surgically treated with primary bilateral medial rectus (BMR) recessions. The study also compared preoperative and postoperative measurements in subjects with a high AC/A ratio to a normal AC/A ratio to assess surgical outcomes. Materials and Methods: 122 subjects were divided into 2 groups based on AC/A ratio into high AC/A ratio and normal AC/A ratio The subjects with high AC/A were treated with bifocal management if they had near persistent ET of âĽ10Î in full cycloplegic correction and not if they had far ET of âĽ10Î. Target angle at the time of the surgery was assessed with stereopsis presence via positive butterfly/fly, and near and distance deviations â¤10Î within orthophoria. These success outcomes were compared in subjects with normal AC/A ratio and AC/A ratio groups. The collected data were subjected to statistical evaluation
Effects of extracellular proteome on wheat straw pretreatment during solid-state fermentation of Phlebia radiata ATCC 64658
Biological pretreatment of lignocellulosic biomass potentially offers a less energy intensive alternative to chemical pretreatment for the reduction of recalcitrance towards cellulolytic enzymes, but possesses some disadvantages, including a slow rate and loss of polysaccharides. This study characterizes the biodegradation of wheat straw by Phlebia radiata, a white rot fungus capable of secreting three major classes of ligninolytic enzymes: lignin peroxidase, manganese peroxidase, and laccase under natural conditions. We investigated the correlation between synergistic action of fungal enzymes and characteristics of the pretreated biomass. The results showed a sequential expression of enzymes over the course of a three-week pretreatment, with members of the peroxidase family being expressed in week one, followed by laccase expression starting in week two which continued until the course of pretreatment. This highlights the synergy of ligninolytic enzymes in the selective degradation pattern for wheat straw. 1Hâ13C HSQC NMR spectroscopy results demonstrated reduced amounts of syringyl (S) and hydroxyphenyl (H) lignin after pretreatment. Moreover, the reduction in H lignin was also seen in Pyrolysis â GC/MS and FT-IR results. This strongly suggests that this unique lignin modification pattern is associated with P. radiata extracellular proteome, as expressed during the solid-state fermentation (pretreatment) of wheat straw.
[Display omitted]
â˘Ligninolytic enzymes of Phlebia radiata work synergistically in wheat straw degradation.â˘MnP is secreted early in the process, to generate substrate for laccases.â˘Laccase allows the lignin modification to continue via relatively higher breakdown of H-units than G and S subunits.â˘Sequential secretion strategy serves the purpose of an efficient biodegradation
Structural Modification of Lignin and Characterization of Pretreated Wheat Straw by Ozonation
Ozonolysis is potentially an effective
method for pretreating lignocellulosic
biomass to improve the production of fermentable sugars via enzymatic
hydrolysis. Further understanding of the ozonolysis process and identifying
specific lignin structural changes are crucial for improving the pretreatment
process. Investigation into pretreatment of wheat straw using ozonolysisis
is reported in this paper, with special emphasis on selective modification/degradation
of lignin subunits. The ozonolysis was performed for 2 h with less
than 60 mesh particles in order to achieve maximum lignin oxidation.
The results showed that the lignin structure was significantly modified
under these conditions, leading to higher sugar recovery of more than
50% which increased from 13.11% to 63.17% corresponding to the control
and ozone treated samples, respectively. Moisture content was found
to be an important parameter for improving sugar recovery. Ninety
percent (w/w) moisture produced the highest sugar recovery. The concentration
of acid soluble lignin in the ozone treated sample increased from
4% to 11% after 2 h treatment. NMR analysis revealed that the S2/6
and G2 lignin units in the wheat straw were most prone to oxidation
by ozone as the concentration of aromatic units decreased while the
carboxylic acids became more abundant. The experimental data suggest
the degradation of β-O-4 moieties and aromatic ring opening
in lignin subunits. The pyrolysis-gas chromatography/mass spectrometry
results revealed that the rate of lignin unit degradation was in the
following order: syringyl > guaiacyl > <i>p</i>-hydroxyphenyl.
Long ozone exposure resulted in few condensed lignin structure formation.
In addition, the formation of condensed units during this process
increased the activation energy from ASTM-<i>E</i>, 259.74
kJ/mol; Friedman-<i>E</i>, 270.08 kJ/mol to ASTM-<i>E</i>, 509.29 kJ/mol; Friedman-<i>E</i>, 462.17 kJ/mol.
The results provide new information in overcoming lignin barrier for
lignocellulose utilization
Structural and Thermal Characterization of Wheat Straw Pretreated with Aqueous Ammonia Soaking
Production of renewable fuels and chemicals from lignocellulosic
feedstocks requires an efficient pretreatment technology to allow
ready access of polysaccharides for cellulolytic enzymes during saccharification.
The effect of pretreatment on wheat straw through a low-temperature
and low-pressure soaking aqueous ammonia (SAA) process was investigated
in this study using Fourier transform infrared (FTIR), pyrolysisâgas
chromatography/mass spectroscopy (Py-GC/MS), solid and liquid state
nuclear magnetic resonance (NMR), and thermogravimetry/differential
thermogravimetry (TG/DTG) to demonstrate the changes in lignin, hemicellulose,
and cellulose structure. After treatment of 60 mesh wheat straw particles
for 60 h with 28â30% ammonium hydroxide (1:10 solid/liquid)
at 50 °C, sugar recovery increased from 14% (untreated) to 67%
(SAA treated). The FTIR study revealed a substantial decrease in absorbance
of lignin peaks. Solid and liquid state NMR showed minimal lignin
structural changes with significant compositional changes. Activation
energy of control and pretreated wheat straw was calculated according
to the Friedman and ASTM methods and found to be decreased for SAA-treated
wheat straw, from 259 to 223 kJ/mol. The SAA treatment was shown to
remove significant amounts of lignin without strongly affecting lignin
functional groups or structure
Recommended from our members
Simulation of the ozone pretreatment of wheat straw
â˘Two models for ozonolysis pretreatment of wheat straw were developed.â˘First study that takes into account the residual lignin.â˘Compared cuticle model with the existing general model for ozonolysis of biomass.â˘Cuticle model better fit with experimental data.
Wheat straw is a potential feedstock in biorefinery for sugar production. However, the cellulose, which is the major source of sugar, is protected by lignin. Ozonolysis deconstructs the lignin and makes cellulose accessible to enzymatic digestion. In this study, the change in lignin concentration with different ozonolysis times (0, 1, 2, 3, 5, 7, 10, 15, 20, 30, 60min) was fit to two different kinetic models: one using the model developed by Garcia-Cubero et al. (2012) and another including an outer mass transfer barrier or âcuticleâ region where ozone mass transport is reduced in proportion to the mass of unreacted insoluble lignin in the cuticle. The kinetic parameters of two mathematical models for predicting the soluble and insoluble lignin at different pretreatment time were determined. The results showed that parameters derived from the cuticle-based model provided a better fit to experimental results compared to a model without a cuticle layer
Biorefinery processing of waste to supply cost-effective and sustainable inputs for two-stage microalgal cultivation
Overcoming obstacles to commercialization of algal-based processes for biofuels and co-products requires not just piecemeal incremental improvements, but rather a comprehensive and fundamental re-consideration starting with the selected algae and its associated cultivation, harvesting, biomass conversion, and refinement. A novel two-stage process designed to address challenges of mass outdoor microalgal cultivation for biofuels and co-products was previously demonstrated using an oleaginous, haloalkaline-tolerant, and multi-trophic green Chlorella vulgaris. ALP2 from a soda lake. This involved cultivating the microalgae in a fermenter heterotrophically or photobioreactor mixotrophically (first-stage) to rapidly obtain high cell densities and inoculate an open-pond phototrophic culture (second-stage) featuring high levels of NaHCO3, pH, and salinity. An improved two-stage cultivation that instead sustainably used as more cheap and sustainable inputs the organic carbon, nitrogen, and phosphorous from fractionation of waste was here demonstrated in a small-scale biorefinery process. The first cultivation stage consisted of two simultaneous batch flask cultures featuring (1) mixotrophic cell productivity of 7.25 Ă 107 cells mLâ1 dayâ1 on BG-110 medium supplemented with 1.587 g Lâ1 urea and an enzymatic hydrolysate of pre-treated (torrefaction + grinding + ozonolysis + soaking ammonia) wheat-straw that corresponded to 10 g Lâ1 glucose, and (2) mixotrophic cell productivity of 2.25 Ă 107 cells mLâ1 dayâ1 on BG-110 medium supplemented with 1.587 g Lâ1 urea and a purified and de-toxified condensate of pre-treated (torrefaction + grinding) wheat straw that corresponded to 0.350 g Lâ1 of potassium acetate. The second cultivation stage featured 1H NMR-determined phototrophic lipid productivity of 0.045 g triacylglycerides (TAG) Lâ1 dayâ1 on BG-110 medium supplemented with 16.8 g Lâ1 NaHCO3 and fed batch-added 22% (v/v) anaerobically digested food waste effluent at HCl-mediated pH 9.</jats:p