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Concentration effects on peptide elution from pendant PEO layers
Get PDFIn earlier work, we have provided direction for development of responsive drug delivery systems based on modulation of structure and amphiphilicity of bioactive peptides entrapped within pendant polyethylene oxide (PEO) brush layers. Amphiphilicity promotes retention of the peptides within the hydrophobic inner region of the PEO brush layer. In this work, we describe the effects of peptide surface density on the conformational changes caused by peptide-peptide interactions, and show that this phenomenon substantially affects the rate and extent of peptide elution from PEO brush layers. Three cationic peptides were used in this study: the arginine-rich amphiphilic peptide WLBU2, the chemically identical but scrambled peptide S-WLBU2, and the non-amphiphilic homopolymer poly-L-arginine (PLR). Circular dichroism (CD) was used to evaluate surface density effects on the structure of these peptides at uncoated (hydrophobic) and PEO-coated silica nanoparticles. UV spectroscopy and a quartz crystal microbalance with dissipation monitoring (QCM-D) were used to quantify changes in the extent of peptide elution caused by those conformational changes. For amphiphilic peptides at sufficiently high surface density, peptide-peptide interactions result in conformational changes which compromise their resistance to elution. In contrast, elution of a non-amphiphilic peptide is substantially independent of its surface density, presumably due to the absence of peptide-peptide interactions. The results presented here provide a strategy to control the rate and extent of release of bioactive peptides from PEO layers, based on modulation of their amphiphilicity and surface density.Keywords: α-Helix,
PEO brush,
Cationic amphiphilic peptides,
Polyarginine,
WLBU2,
Coiled-coils,
Circular dichroism (CD),
Peptide elutio
MyersJamesHorticultureVariationBroccoliCultivar.pdf
No full textOrganic agriculture requires cultivars that can adapt to organic crop management systems without the use of synthetic
pesticides as well as genotypes with improved nutritional value. The aim of this study encompassing 16 experiments was to
compare 23 broccoli cultivars for the content of phytochemicals associated with health promotion grown under organic
and conventional management in spring and fall plantings in two broccoli growing regions in the US (Oregon and Maine).
The phytochemicals quantified included: glucosinolates (glucoraphanin, glucobrassicin, neoglucobrassin), tocopherols (δ-,
γ-, α-tocopherol) and carotenoids (lutein, zeaxanthin, β-carotene). For glucoraphanin (17.5%) and lutein (13%), genotype
was the major source of total variation; for glucobrassicin, region (36%) and the interaction of location and season (27.5%);
and for neoglucobrassicin, both genotype (36.8%) and its interactions (34.4%) with season were important. For δ- and γ-tocopherols,
season played the largest role in the total variation followed by location and genotype; for total carotenoids,
genotype (8.41–13.03%) was the largest source of variation and its interactions with location and season. Overall,
phytochemicals were not significantly influenced by management system. We observed that the cultivars with the highest
concentrations of glucoraphanin had the lowest for glucobrassicin and neoglucobrassicin. The genotypes with high
concentrations of glucobrassicin and neoglucobrassicin were the same cultivars and were early maturing F₁ hybrids.
Cultivars highest in tocopherols and carotenoids were open pollinated or early maturing F₁ hybrids. We identified distinct
locations and seasons where phytochemical performance was higher for each compound. Correlations among horticulture
traits and phytochemicals demonstrated that glucoraphanin was negatively correlated with the carotenoids and the
carotenoids were correlated with one another. Little or no association between phytochemical concentration and date of
cultivar release was observed, suggesting that modern breeding has not negatively influenced the level of tested
compounds. We found no significant differences among cultivars from different seed companies
Contrasting ion-association behaviour of Ta and Nb polyoxometalates
Get PDFSmall-angle X-ray scattering (SAXS) studies of aqueous [Ta₆O₁₉]⁸⁻
compared to prior studies of aqueous [Nb₆O₁₉]⁸⁻ reveals key
differences in behaviour, which is likely at the root of the difficultly
in developing polyoxotantalate chemistry. Specifically, where
contact ion-pairing dominates between [Nb₆O₁₉]⁸⁻ and its
counterions, solvent-separated ion-pairing between [Ta₆O₁₉]⁸⁻
and its counterions has been unveiled in the current study
FullmerLaurenChemistryContrastingIonAssociation.pdf
No full textSmall-angle X-ray scattering (SAXS) studies of aqueous [Ta₆O₁₉]⁸⁻
compared to prior studies of aqueous [Nb₆O₁₉]⁸⁻ reveals key
differences in behaviour, which is likely at the root of the difficultly
in developing polyoxotantalate chemistry. Specifically, where
contact ion-pairing dominates between [Nb₆O₁₉]⁸⁻ and its
counterions, solvent-separated ion-pairing between [Ta₆O₁₉]⁸⁻
and its counterions has been unveiled in the current study
Effects of Dead Load and Multiple Earthquake Loadings on Seismic Performance of Wood-Frame Shear Walls
Get PDFGoals of this preliminary study are to better understand (1) earthquake performance of wood-frame shear walls carrying gravity loads, compared with walls without gravity load, and (2) performance of walls subjected to a sequence of earthquake motions, compared with walls subjected to a single earthquake.
Tests with simulated earthquake ground motions were conducted on 2,440 by 2,440-mm (8 by 8-ft) walls with 38 by 89-mm (nominal 2 by 4) Douglas-fir studs at 610 mm (24 in.) on center. Two oriented strand board (OSB) panels were installed and fastened vertically to the frame, and two gypsum wallboard panels were installed opposite the OSB. Partially anchored (PA) walls had two anchor bolts on the sill plate. In addition to the anchor bolts, fully anchored (FA) walls included hold-downs installed at the end studs. Ground motions were scaled to the 10 percent in 50 years probability of exceedance design level for Seattle, Washington, the traditional level associated with life safety performance.
For PA walls with dead load, failure modes were consistent with tests without dead load; however, additional fastener damage, common to FA walls, resulted from the additional resistance to overturning. PA walls realized a greater improvement in performance from dead load application compared with FA walls; performance appears to approach that of FA walls when dead load is applied. FA and PA walls subjected to a sequence of earthquake motions showed wall performance about the same as that of walls subjected to a single scaled earthquake motion
Bearing Strength Capacity of Continuous Supported Timber Beams: Unified Approach for Test Methods and Structural Design Codes
Get PDFBearing or compressive-strength capacity perpendicular to the grain of timber beams is a troublesome issue. Not only do many different load cases occur in practice that are not covered by structural timber design codes, but also these codes provide only a basic provision and vary throughout continents. Code design rules require the standardized compressive or bearing strength to be determined by test standards. An assessment of the results of standard test methods of the European Union, North America, and Australia/New Zealand shows incompatibility. It is demonstrated how previously incompatible results can be made compatible by using a physical model and some calibration tests. The proposed model offers a consistent and simple way to bridge the differences between both test standards and structural design codes
Performance of partially and fully anchored wood-frame shear walls under earthquake loads
Get PDFThe objectives of this study were to evaluate the performance of wood-frame shear walls under monotonic, cyclic, and earthquake loads by: 1) comparing performance under each loading protocol; 2) evaluating effects of anchorage; and 3) eval-uating performance qualitatively and quantitatively with respect to code-defined performance measures. Tests were conducted on 2440 by 2440 mm walls with 38 by 89 mm (2 by 4) Douglas-fir studs at 610 mm on center. Each wall was sheathed with two 1220 by 2440 by 11.1 mm oriented strandboard (OSB) panels and two 12.7 mm gypsum wallboard (GWB) panels installed vertically on the face opposite the structural panel sheathing. Eight walls were tested using two historical subduction zone ground motions scaled to a 10 percent in 50 year probability of exceedance for Seattle, with a 4545 kg seismic mass. Two partially anchored and two fully anchored walls were tested using each earthquake time history. Earthquake tests exhibited lower peak strength and initial stiffness than similar walls tested monotonically. Various ground motions produced similarly shaped asymmetrical load-deflection envelopes. Fully anchored walls exhibited a limit state with severe pinching in the hys-teresis curve beyond which performance variability increased dramatically. Maximum transient drift for six of eight tests exceeded the 3.0 percent drift limit for collapse prevention performance in ASCE 41. Maximum drift was similar between fully and partially anchored walls
Practical Modeling for Wind Load Paths in a Realistic Light-Frame Wood House
Get PDFThe objective of this study was to develop and validate practical modeling methods for investigating load paths and system behavior in a realistic light-frame wood structure. The modeling methods were validated against full-scale tests on subassemblies and an L-shaped house. The model of the L-shaped house was then modified and used to investigate the effects of reentrant corners, wall openings, and gable-end retrofits on system behavior and load paths. Results showed that the effects of adding reentrant corners and wall openings on uplift load distributions were dependent on the orientation of the trusses with respect to the walls. Openings added to walls parallel to the trusses have the least effect on loads carried by the remaining walls in the building. Varying reentrant corner dimensions under design wind loads caused increasing degrees of torsion throughout the house depending on the relative location and stiffness of the in-plane walls (parallel to the wind loads) and the assumed direction of the wind loads. Balancing the stiffness of the walls on either side of the house with the largest reentrant corner helped to decrease torsion in the structure under lateral loads. Finally, although previous full-scale tests on gable-end sections verified the effectiveness of the gable-end retrofit that was recently adopted into recent Florida building code, questions remained about the effects of the retrofit on torsion in a full building. The current study found that adding the gable-end retrofits to the L-shaped house did not cause additional torsion
KennedyPatriciaFisheriesWildlifeManagingWholeLandscape.pdf
No full textThe reality confronting ecosystem managers today is one of heterogeneous, rapidly transforming landscapes,
particularly in the areas more affected by urban and agricultural development. A landscape management
framework that incorporates all systems, across the spectrum of degrees of alteration, provides a fuller set of
options for how and when to intervene, uses limited resources more effectively, and increases the chances of
achieving management goals. That many ecosystems have departed so substantially from their historical trajectory
that they defy conventional restoration is not in dispute. Acknowledging novel ecosystems need not
constitute a threat to existing policy and management approaches. Rather, the development of an integrated
approach to management interventions can provide options that are in tune with the current reality of rapid
ecosystem change
ColeRexBotanyPlantPathologyDiscoveryNovelTranscripts.pdf
No full textBACKGROUND:
Plant gametophytes play central roles in sexual reproduction. A hallmark of the plant life
cycle is that gene expression is required in the haploid gametophytes. Consequently, many
mutant phenotypes are expressed in this phase.
RESULTS:
We perform a quantitative RNA-seq analysis of embryo sacs, comparator ovules with the
embryo sacs removed, mature pollen, and seedlings to assist the identification of
gametophyte functions in maize. Expression levels were determined for annotated genes in
both gametophytes, and novel transcripts were identified from de novo assembly of RNA-seq
reads. Transposon-related transcripts are present in high levels in both gametophytes,
suggesting a connection between gamete production and transposon expression in maize not
previously identified in any female gametophytes. Two classes of small signaling proteins
and several transcription factor gene families are enriched in gametophyte transcriptomes.
Expression patterns of maize genes with duplicates in subgenome 1 and subgenome 2
indicate that pollen-expressed genes in subgenome 2 are retained at a higher rate than
subgenome 2 genes with other expression patterns. Analysis of available insertion mutant
collections shows a statistically significant deficit in insertions in gametophyte-expressed
genes.
CONCLUSIONS:
This analysis, the first RNA-seq study to compare both gametophytes in a monocot, identifies
maize gametophyte functions, gametophyte expression of transposon-related sequences, and
unannotated, novel transcripts. Reduced recovery of mutations in gametophyte-expressed
genes is supporting evidence for their function in the gametophytes. Expression patterns of
extant, duplicated maize genes reveals that selective pressures based on male gametophytic
function have likely had a disproportionate effect on plant genomes