Hybrid Hydrogels for Tissue Engineering

Hydrogels have been widely investigated for their versatility in biomedical applications such as tissue engineering scaffolds and minimally invasive vehicles for site-specific delivery of bioactive molecules. Hybrid hydrogels combine the strengths of intrinsic bioactivity from naturally derived materials and superior control over network physical and chemical properties from synthetic materials. The most prominent approach in three-dimensional (3D) hybrid matrices is the use of MMP-sensitive peptides derived from native extracellular matrix molecules to crosslink synthetic polymers. These peptide-based techniques have several limitations such as high cost, limited mechanical properties, and reduced degradation kinetics that limit the network crosslinking density and mechanical properties. This led us to develop a novel hydrid hydrogel system, in situphotopolymerizable, degradable, poly(ethylene glycol) (PEG) diacrylate / hyaluronic acid (HA) semi-interpenetrating networks (semi-IPNs). In the first set of studies, we determined the effects of network composition (PEGdA and HA molecular weight and concentration) on 3D cell spreading and identified polymerization-induced phase separation as the underlying mechanism responsible for the ability of PEGdA/HA semi-IPNs to support 3D cell spreading. Semi-IPNs with optimal network composition including a blend of three different PEGdA providing improved degradation kinetics demonstrated the ability to support long-term fibroblast cell spreading, migration, and network formation. In addition, the selected semi-IPNs were also found to possess elastic moduli significantly higher than most alternative hybrid hydrogels and within the range reported as optimal for osteogenic differentiation of mesenchymal stem cells. In second study, we investigated the ability of the semi-IPNs to support hMSC differentiation as a preliminary study towards bone tissue engineering application. Gene expression, alkaline phosphatase activity, histological analysis, and calcium quantification demonstrated the semi-IPN’s ability to support osteogenic differentiation over 35 days of culture. In the final study, we incorporated poly-L-lactic acid (PLLA) nanospheres in semi-IPNs to test the hypothesis that provision of hydrophobic domains capable of supporting higher protein adsorption than the PEG network could increase extracellular matrix accumulation. Significantly increased collagen deposition was observed in histological sections and by quantitative analysis. Overall, the results of this work suggest that PEGdA / HA semi-IPNs and their composite derivatives offer potential as a hybrid matrices for therapeutic cell transplantation. In the future, the biofunctionality of these hybrid networks can be further enhanced by inclusion of growth factors or biochemicals

Enhancing quantum entanglement for continuous variables by a coherent superposition of photon subtraction and addition

We investigate how the entanglement properties of a two-mode state can be improved by performing a coherent superposition operation of photon subtraction and addition, proposed by Lee and Nha [Phys. Rev. A 82, 053812 (2010)], on each mode. We show that the degree of entanglement, the EPR-type correlation, and the performance of quantum teleportation can be all enhanced for the output state when the coherent operation is applied to a two-mode squeezed state. The effects of the coherent operation are more prominent than those of the mere photon subtraction and the addition particularly in the small squeezing regime, whereas the optimal operation becomes the photon subtraction in the large-squeezing regime.Comment: 6 pages, 6 figures, published versio

Vowel Sound Disambiguation for Intelligible Korean Speech Synthesis

PACLIC 19 / Taipei, taiwan / December 1-3, 200

Ecological Studies of Velvetbean Caterpillar, Anticarsia Gemmatalis Hubner, Pupae in Louisiana Soybean Fields.

The microhabitat distribution of velvetbean caterpillar (VBC), Anticarsia gemmatalis Hubner (Lepidoptera: Noctuidae) was studied in soybean field cages and fields during 1985, 1986 and 1987. Larval density did not affect pupal horizontal distribution patterns related to direction and distance from the plant row. Pupae were found equally on both sides of soybean plant rows in a cage study. Pupae were found on and below the soil surface, but not on the plant. In 51 cm row spacing, both equal number and similar dispersion pattern of pupae were found on either side of the plant row. In 91 cm row spacing, pupal densities were slightly biased to the north side (4:6) of the plant rows in 1986 and this trend was extreme (2:8) in 1987 when plant canopy was barely closed. The degree of plant canopy closure appeared to influence pupal horizontal distribution. In 91 cm row spacing, pupal densities varied inversely with distance from the row. Taylor\u27s power law analyses indicated that VBC pupal spatial dispersion patterns were random in both 51 and 91 cm row spacings for a sample unit (90 by 90 cm) and a subsample unit (90 by 15 cm parallel to the plant row and 15 by 90 cm across the plant row in 51 and 91 cm row spacings, respectively). Significant linear relationships between larval and pupal densities were found for all three larval size classes (small, 1st and 2nd instars (0-12.5 mm long); medium, 3rd and 4th instars (12.5-25 mm long); large, ($\geq$25 mm long)) in 51 and 91 cm row spacing fields in 1986 but only for medium larvae in 1987. Simple linear regression equations were developed to predict pupal density from larval density. The survivorship and predation of VBC pupae were studied in 1986 and 1987. Seven species of insects including ground beetles, tiger beetles, earwigs and the red imported fire ant, Solenopsis invicta Buren, were identified in laboratory feeding trials as VBC pupal predators. Predation was the principal mortality factor, accounting for 37.5 to 95.2% mortality in plots with fire ants. (Abstract shortened with permission of author.)

Young Adult Donor Bone Marrow Infusions into Female Mice Postpone Age-Related Reproductive Failure and Improve Offspring Survival

The female reproductive axis is the first major organ system of the body to fail with advancing age. In addition to a permanent cessation of fertile potential, the loss of cyclic ovarian function in humans heralds the onset of menopause, which in turn underlies the emergence of a diverse spectrum of health issues in aging women. Recently, it was reported that bone marrow (BM) transplantation (BMT) into adult female mice conditioned a week earlier with highly cytotoxic drugs rescues ovarian function and fertility. Herein we show in mice receiving no prior conditioning regimen that once-monthly infusions of BM-derived cells retrieved from young adult female donors bearing an enhanced green fluorescent protein (EGFP) transgene sustain the fertile potential of aging wild-type females long past their time of normal reproductive senescence. The fertility-promoting effects of female donor BM are observed regardless whether the infusions are initiated in young adult or middle-aged females. Although the mechanism by which BM infusions benefit the reproductive performance of aging females remains to be elucidated, the absence of EGFP-expressing offspring suggests that it does not depend on development of mature eggs derived from germline-committed cells in the donor marrow. However, donor BM-derived somatic cells accumulate in the recipients, indicating efficient donor cell engraftment without prior conditioning. These findings provide a strong impetus to further explore development of adult stem cell-based technologies to safely extend function of the female reproductive axis into advanced age without the need for toxic pre-conditioning protocols routinely used in other models of stem cell delivery

Improved prediction of ligand-protein binding affinities by meta-modeling

The accurate screening of candidate drug ligands against target proteins through computational approaches is of prime interest to drug development efforts, as filtering potential candidates would save time and expenses for finding drugs. Such virtual screening depends in part on methods to predict the binding affinity between ligands and proteins. Given many computational models for binding affinity prediction with varying results across targets, we herein develop a meta-modeling framework by integrating published empirical structure-based docking and sequence-based deep learning models. In building this framework, we evaluate many combinations of individual models, training databases, and linear and nonlinear meta-modeling approaches. We show that many of our meta-models significantly improve affinity predictions over individual base models. Our best meta-models achieve comparable performance to state-of-the-art exclusively structure-based deep learning tools. Overall, we demonstrate that diverse modeling approaches can be ensembled together to gain substantial improvement in binding affinity prediction while allowing control over input features such as physicochemical properties or molecular descriptors.Comment: 61 pages, 3 main tables, 6 main figures, 6 supplementary figures, and supporting information. For 8 supplementary tables and code, see https://github.com/Lee1701/Lee2023

Origin of the dust emission from Tycho's SNR

Aims: We investigate the spatial distribution of dust emission around Tycho's SNR to understand its origin. We distinguish the dust associated with the SNR from that of the surrounding ISM. Methods: We performed mid- to far-infrared imaging observations of the remnant at wavelengths of 9, 15, 18, 24, 65, 90, 140, and 160um using the Infrared Camera and the Far-Infrared Surveyor onboard AKARI. We compared the AKARI images with the Suzaku X-ray image and the 12CO image of Tycho's SNR. Results: All the AKARI images except the 9, 140, and 160um band images show a shell-like emission structure with brightness peaks at the north east (NE) and north west (NW) boundaries, sharply outlining part of the X-ray shell. The 140 and 160um bands are dominated by cold dust emission from the surrounding ISM near the NE boundary. Conclusion: We conclude that the dust emission at the NE boundary comes from the ambient cloud interacting with the shock front, while the origin of the dust emission at the NW boundary is rather unclear because of the absence of prominent interstellar clouds near the corresponding region. We cannot rule out the possibility that the latter is mostly of an SN ejecta origin.Comment: Accepted for publication in A&A lette