Structural reorganisation of cellulose fibrils in hydrothermally deconstructed lignocellulosic biomass and relationships with enzyme digestibility

Background: The investigation of structural organisation in lignocellulose materials is important to understand changes in cellulase accessibility and reactivity resulting from hydrothermal deconstruction, to allow development of strategies to maximise bioethanol process efficiencies. To achieve progress, wheat straw lignocellulose and comparative model wood cellulose were characterised following increasing severity of hydrothermal treatment. Powder and fibre wide-angle X-ray diffraction techniques were employed (WAXD), complemented by enzyme kinetic measurements up to high conversion. Results: Evidence from WAXD indicated that cellulose fibrils are not perfectly crystalline. A reduction in fibril crystallinity occurred due to hydrothermal treatment, although dimensional and orientational data showed that fibril coherency and alignment were largely retained. The hypothetical inter-fibril spacing created by hydrothermal deconstruction of straw was calculated to be insufficient for complete access by cellulases, although total digestion of cellulose in both treated straw and model pulp was observed. Both treated straw and model pulps were subjected to wet mechanical attrition, which caused separation of smaller fibril aggregates and fragments, significantly increasing enzyme hydrolysis rate. No evidence from WAXD measurements was found for preferential hydrolysis of non-crystalline cellulose at intermediate extent of digestion, for both wood pulp and hydrothermally treated straw. Conclusions: The increased efficiency of enzyme digestion of cellulose in the lignocellulosic cell wall following hydrothermal treatment is a consequence of the improved fibril accessibility due to the loss of hemicellulose and disruption of lignin. However, incomplete accessibility of cellulase at the internal surfaces of fibrillar aggregates implies that etching type mechanisms will be important in achieving complete hydrolysis. The reduction in crystalline perfection following hydrothermal treatment may lead to an increase in fibril reactivity, which could amplify the overall improvement in rate of digestion due to accessibility gains. The lack of preferential digestion of non-crystalline cellulose is consistent with the existence of localised conformational disorder, at surfaces and defects, according to proposed semicrystalline fibril models. Cellulases may not interact in a fully selective manner with such disordered environments, so fibril reactivity may be considered as a function of average conformational states

Application of Design of Experiments to Flight Test: a Case Study

Modern flight test tends to be a complex, expensive undertaking so any increases in efficiency would result in considerable savings. Design of experiments is a statistical methodology which enables a highly efficient investigation where only the samples needed are collected and analyzed. the application of design of experiments to the design of flight test can result in a significant increase in test efficiency. Increased information is garnered from the data collected while the number of data points required to understand the system is reduced. in this effort, an actual flight test program serves as a case study to compare and contrast five different designs to explore the flight test envelope: the classic subject-matter-expert (SME) generated survey method, the SME-generated points augmented to a relatively fine mesh orthogonal analysis of variance design, an axial central composite design (CCD), a face-centered CCD plus simplex design, and a Simpson-Landman embedded face-centered CCD. the axial CCD is further expanded by a single point to illustrate the flexibility of the design in response to the interests of the test team. the case study data are analyzed using each designed experiment, and the results are compared and contrasted as a cost-benefit relationship between flight test resources expended (i.e. flight hours) and system understanding gained (i.e. statistical confidence and power). the design of experiments methodologies, as applied to this case study, generally show a 50 to 80 percent reduction in flight test resources expended to gain similar levels of understanding of the system under test. These savings can be applied to other programs, used to educate design changes before testing an improved system, allow for flexible investigation into areas of interest to the test team, or replicate the test points resulting in a better understanding of systemic error. in an era of restricted budgets and timelines, careful design and thoughtful analysis of flight test experiments can make the difference between a failed or cancelled flight test program and the successful fielding of a needed capability

Impact of altered cell wall composition on saccharification efficiency in stem tissue of Arabidopsis RABA GTPase-deficient knockout mutants

Use of biomass for second-generation biofuel production is severely hindered by the inherent recalcitrance of the plant cell wall to digestion. Trafficking is crucial for compartmentalisation within the cell. This process is partly regulated by small Rab GTPase proteins. In particular, control of trafficking to the cell wall is regulated through the RABA clade. Manipulation of this regulatory system offers tantalising opportunities for manipulation of cell wall composition and hence recalcitrance. Trafficking-defective rabA mutants have already been shown to impact cell wall composition. To study the impacts of these mutants on cell wall digestion, we developed a saccharification process for Arabidopsis based on the hot water method. We then showed that following pre-treatment, stems from the T-DNA knockouts of the three RABA4 genes expressed in Arabidopsis stem show an increased sugar release on saccharification. These rabA4 mutants have been shown to impact the “hemicellulose-rich” fraction during cell wall fractionation. Furthermore, we go on to show that these mutant lines also show increased sugar release when subjected to saccharification without pre-treatment. Finally, we used X-ray diffraction to show that rabA4 mutants had no impact on cellulose crystallinity, thus supporting the hypothesis that the increases in saccharification were not due to alterations of the cellulose microfibrils but were a direct effect of reduced hemicellulose levels. We also present data to show that the growth characteristics of these plants were unaffected. The data obtained from these lines are most easily explained by the reported alteration in hemicellulose increasing pre-treatment efficiency

Effect of preharvest UV-C treatment of tomatoes (Solanum lycopersicon Mill.) on ripening and pathogen resistance

Treatment with UV-C of tomato fruit on the vine was conducted using a mobile unit that was designed to be conveyed between the rows of tomato plants in a commercial glasshouse. Trusses of fruit both at the ripe and mature green phase were treated with UV-C doses of 3 and 8 kJ/m2. Ripe fruit were picked 8 h after treatment and kept at room temperature for up to 16 d during which colour development and texture were monitored and compared to untreated controls. Mature green fruit treated on the vine with UV-C doses of 3 or 8 kJ/m2 showed only a slight loss in green pigmentation in contrast to the tomato colour index (TCI) of control fruit which increased sharply 5 d after treatment. The TCI of ripe fruit treated with UV-C at a dose of 8 kJ/m2 showed a lag of 10 d before increasing to a final value comparable to that of untreated fruit. Fruit treated with a dose of 3 kJ/m2 did not display a lag but the increase in TCI occurred at a lower rate than for the controls. Firmness remained higher in fruit treated with the highest UV-C dose compared to fruit treated with the lower UV-C dose and controls. Fruit covered with UV impermeable film on the same plants as those that had received a UV-C dose of 3 kJ/m2 had become ripe by day 6 in a manner similar to that of the controls. By contrast, fruit from trusses adjacent to those that had been treated with a UV-C dose of 8 kJ/m2 remained green over the same period of time. Ripe fruit treated as described above were inoculated with spores of Penicillium digitatum after UV-C treatment and their firmness monitored over 12 d. A dose response effect was found with fruit treated at the highest dose remaining firmer than those treated at the lower dose and the controls

Tryptic digestion coupled with ambient DESI and LESA mass spectrometry enables identification of skeletal muscle proteins in mixtures and distinguishes between beef, pork, horse, chicken and turkey meat

The use of ambient desorption electrospray ionization (DESI-MS) mass spectrometry and liquid extraction surface analysis mass spectrometry (LESA-MS) is explored for the first time to analyse skeletal muscle proteins obtained from mixture of standard proteins and raw meat. Single proteins and mixtures of up to five proteins (myoglobin, troponin C, actin, BSA, tropomyosin) were deposited onto a polymer surface, followed by in-situ tryptic digestion and comparative analysis using DESI-MS and LESA-MS using tandem electrospray MS. Peptide peaks specific to individual proteins were readily distinguishable with good signal-to-noise ratio in the five-component mixture. LESA-MS gave a more stable analysis and greater sensitivity compared with DESI-MS. Meat tryptic digests were subjected to peptidomics analysis by DESI-MS and LESA-MS. Bovine, horse, pig, chicken and turkey muscle digests were clearly discriminated using multivariate data analysis (MVA) of the peptidomic datasets. The most abundant skeletal muscle proteins were identified and correctly classified according to the species following MS/MS analysis. The study shows, for the first time, that ambient ionization techniques such as DESI-MS and LESA-MS have great potential for species-specific analysis and differentiation of skeletal muscle proteins by direct surface desorption

Vacuum Strength of Two Candidate Glasses for a Space Observatory

The strengths of two candidate glass types for use in a space observatory were measured. Samples of ultra-low expansion glass (ULE) and borosilicate (Pyrex) were tested in air and in vacuum at room temperature (20 C) and in vacuum after being heated to 200 C. Both glasses tested in vacuum showed an increase in strength over those tested in air. However, there was no statistical difference between the strength of samples tested in vacuum at room temperature and those tested in vacuum after heating to 200 C

Vacuum Strength of Two Candidate Glasses for a Space Observatory

The strengths of two candidate glass types for use in a space observatory were measured. Samples of ultra-low expansion glass (ULE) and borosilicate (Pyrex) were tested in air and in vacuum at room temperature (20 degrees C) and in vacuum after being heated to 200 degrees C. Both glasses tested in vacuum showed a significant increase in strength over those tested in air. However, there was no statistical difference between the strength of samples tested in vacuum at room temperature and those tested in vacuum after heating to 200 degrees C

Concertacion y seguridad social : de la legitimidad social a la legitimidad tecnocrática

El estudio aborda la concertación, un análisis de las políticas de seguridad social constatando su evolución desde una legitimidad social a una legitimidad tecnocrática en la crisis del welfare state y en la crisis económica con particular referencia al sistema español. Desde la normalización de la acción política de los sindicatos y agentes sociales en sus diversas manifestaciones, como la participación institucional y la "legislación negociada" en la búsqueda del consenso y el negociado de intercambios en el marco político frente a la imposición unilateral. La frustración de la concertación social se produce cuando el gobierno interpreta la democracia como algo puramente aritmético de mayorías que ejercen sin más el poder, en épocas de debilidad sindical, de debilidad del estado nación, de dificultades para las políticas redistributivas, de reforzamiento de los planteamientos neoliberales. La búsqueda de legitimidad en el pacto social no se ve en estas ocasiones como necesaria sino que la legitimidad se traslada al discurso economicista y tecnocrático, no político. Se vuelve a la búsqueda de una legitimidad a través del mercado y del intercambio entre particulares.L'estudi aborda la concertació, una anàlisi de les polítiques de seguretat social constatant la seva evolució des d'una legitimitat social a una legitimitat tecnocràtica en la crisi del welfare state i en la crisi econòmica amb particular referència al sistema espanyol. Des de la normalització de l'acció política dels sindicats i agents socials en les seves diverses manifestacions, com la participació institucional i la "legislació negociada" en la cerca del consens i el negociat d'intercanvis en el marc polític enfront de la imposició unilateral. La frustració de la concertació social es produeix quan el govern interpreta la democràcia com alguna cosa purament aritmètic de majories que exerceixen sense més el poder, en èpoques de feblesa sindical, de feblesa de l'estat nació, de dificultats per a les polítiques redistributives, de reforçament dels plantejaments neoliberals. La cerca de legitimitat en el pacte social no es veu en aquestes ocasions com a necessària sinó que la legitimitat es trasllada al discurs economicista i tecnocràtic, no polític. Es torna a la cerca d'una legitimitat a través del mercat i de l'intercanvi entre particulars.The study addresses the conclusion an analysis of policies of social security noting exposing its evolution from a social legitimacy to a technocratic legitimacy in the crisis of the welfare state and the economic crisis with particular reference to the Spanish system. Since the normalization of the political action of the trade unions and social partners in its various manifestations, such as institutional participation and negotiated "legislation" in the search for consensus and the Bureau of exchanges in the political framework against the unilateral imposition. The frustration of the social agreement occurs when the Government interprets the democracy as something purely arithmetic of majorities that exercise without more power, in times of Union weakness, weakness of the State nation, of difficulties for redistributive policies, strengthening of neoliberal approaches. The search for legitimacy in the social pact is not on these occasions as necessary but that legitimacy is moved to the economistic and technocratic, non-political speech. Turns to the search for legitimacy through the market and the exchange between individuals

The Cut & Enhance method : selecting clusters of galaxies from the SDSS commissioning data

We describe an automated method, the Cut & Enhance method (CE) for detecting clusters of galaxies in multi-color optical imaging surveys. This method uses simple color cuts, combined with a density enhancement algorithm, to up-weight pairs of galaxies that are close in both angular separation and color. The method is semi-parametric since it uses minimal assumptions about cluster properties in order to minimize possible biases. No assumptions are made about the shape of clusters, their radial profile or their luminosity function. The method is successful in finding systems ranging from poor to rich clusters of galaxies, of both regular and irregular shape. We determine the selection function of the CE method via extensive Monte Carlo simulations which use both the real, observed background of galaxies and a randomized background of galaxies. We use position shuffled and color shuffled data to perform the false positive test. We have also visually checked all the clusters detected by the CE method. We apply the CE method to the 350 deg^2 of the SDSS (Sloan Digital Sky Survey) commissioning data and construct a SDSS CE galaxy cluster catalog with an estimated redshift and richness for each cluster. The CE method is compared with other cluster selection methods used on SDSS data such as the Matched Filter (Postman et al. 1996, Kim et al. 2001), maxBCG technique (Annis et al. 2001) and Voronoi Tessellation (Kim et al. 2001). The CE method can be adopted for cluster selection in any multi-color imaging surveys.Comment: 62 pages, 32 figures, Accepted for publication in the Astronomical Journal, "the CE galaxy cluster catalog can be downloaded from, http://astrophysics.phys.cmu.edu/~tomo/ce/