Wavelength-gated photoreversible polymerization and topology control

We exploit the wavelength dependence of [2 + 2] photocycloadditions and-reversions of styrylpyrene to exert unprecedented control over the photoreversible polymerization and topology of telechelic building blocks. Blue light (λmax = 460 nm) initiates a catalyst-free polymerization yielding high molar mass polymers (Mn = 60 000 g mol-1), which are stable at wavelengths exceeding 430 nm, yet highly responsive to shorter wavelengths. UVB irradiation (λmax = 330 nm) induces a rapid depolymerization affording linear oligomers, whereas violet light (λmax = 410 nm) generates cyclic entities. Thus, different colors of light allow switching between a depolymerization that either proceeds through cyclic or linear topologies. The light-controlled topology formation was evidenced by correlation of mass spectrometry (MS) with size exclusion chromatography (SEC) and ion mobility data. Critically, the color-guided topology control was also possible with ambient laboratory light affording cyclic oligomers, while sunlight activated the linear depolymerization pathway. These findings suggest that light not only induces polymerization and depolymerization but that its color can control the topological outcomes.</p

Wavelength-Orthogonal Stiffening of Hydrogel Networks with Visible Light

Herein, we introduce the wavelength-orthogonal crosslinking of hydrogel networks using two red-shifted chromophores, i.e. acrylpyerene (AP, λ$_{activation}$=410–490 nm) and styrylpyrido[2,3-b]pyrazine (SPP, λ$_{activation}$=400–550 nm), able to undergo [2+2] photocycloaddition in the visible-light regime. The photoreactivity of the SPP moiety is pH-dependent, whereby an acidic environment inhibits the cycloaddition. By employing a spiropyran-based photoacid generator with suitable absorption wavelength, we are able to restrict the activation wavelength of the SPP moiety to the green light region (λ$_{activation}$=520–550 nm), enabling wavelength-orthogonal activation of the AP group. Our wavelength-orthogonal photochemical system was successfully applied in the design of hydrogels whose stiffness can be tuned independently by either green or blue light

Kenbrook Bridge Project

The Kenbrook Bridge Team seeks to address Kenbrook Bible Camp’s need for maintenance and emergency access across a small stream on the property that separates their main office location from cabins on the northwestern portion of the campus. Kenbrook Bible Camp\u27s mission is to facilitate a closer connection to God, self, others, and nature for all guests. The bridge site was selected by the Kenbrook staff based on the greatest need for accessibility. An existing footbridge in this location cannot support passage of heavy equipment used for camp maintenance nor the ATV used for emergency response. The bridge team proposes a 16-foot-long by 8-foot-wide concrete culvert for the site. The culvert has been designed in compliance with AASHTO structural requirements and all elements of the structure are detailed in a complete drawings sheet set, serving as a reference for on-site construction in May. Funding for this work provided by The Collaboratory for Strategic Partnerships and Applied Research.https://mosaic.messiah.edu/engr2022/1001/thumbnail.jp

FUEL PERFORMANCE IMPROVEMENT PROGRAM Power-Ramp Testing and Postirradiation Examination of PCI- Resistant LWR Fuel Rod Designs

This report describes the power-ramp testing results from 10 fuel rods irradiated in the Halden Boiling Water Reactor (HBWR), Halden, Norway. Tne work is part of the Fuel Performance Improvement Program (FPIP), which is sponsored by the U.S. Department of Energy (DUE) and is conducted through the joint efforts of Consumers Power Company, Exxon Nuclear Company, lnc., and Pacific Northwest Laboratory. The objective of the FPlP is to identify and demonstrate fuel concepts with improved pellet-cladding interaction (PCl) behavior that will be capable of extended burnup. The postirradiation examination results obtained from one nonramped rod are also presented. The power-ramping behavior of three basic fuel rod types--rods with annular-pellet fuel, sphere-pac fuel, and dished-pellet (reference) fuel--are compared in terms of mechanisms known to promote PCl failures. The effects of graphite coating on the inside cladding surface and helium pressurization in rods witn annular fuel are also evaluated

Treatment of compound tibia fracture with microvascular latissimus dorsi flap and the Ilizarov technique : A cross-sectional study of long-term outcomes

Background: Extensive compound tibial fractures present reconstructive challenges. The present study aimed to assess the outcomes of microvascular latissimus dorsi (LD) flap combined with the Ilizarov technique for extensive compound tibial fractures with bone loss and bone healing complications. Methods: Patient records were reviewed retrospectively. The Lower Extremity Functional Scale (LEFS), the Disabilities of the Arm, Hand and Shoulder (DASH), and the 15D health-related quality of life (HRQoL) instrument were applied. Results: Between 1989 and 2014, 16 patients underwent reconstruction with a microvascular LD flap and bone transport (11/16) or late bone lengthening (5/16). The mean clinical follow-up time was 6.6 (standard deviation (SD): 6.5) years. Three patients had minor complications requiring reoperation. Partial necrosis of one flap required late flap reconstruction in one case. Late bone grafting was used to enhance union in eight of 16 cases. The mean new bone gain was 3.8 cm (SD: 2.5). Overall, 11 patients completed the questionnaires in a mean of 22.3 years (SD: 2.4) after surgery. The main findings revealed a relatively good function of the reconstructed limb and good shoulder function. The mean HRQoL was comparable to that of an age-standardized sample of the general population. Conclusion: Segmental tibia transport and lengthening to correct limb length discrepancy do not compromise the microvascular muscle flap. Combined microvascular LD flap reconstruction and the Ilizarov technique can be used in treating acute compound tibial defects, pseudoarthrosis, and osteitis, all associated with significant amputation risk. Fair long-term functional outcomes and HRQoL are achieved when these combined techniques are used. (C) 2016 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.Peer reviewe

Ugi multicomponent reaction to prepare peptide–peptoid hybrid structures with diverse chemical functionalities

Monodisperse sequenced peptides and peptoids present unique nano-structures based on their self-assembled secondary and tertiary structures. However, the generation of peptide and peptoid hybrid oligomers in a sequence-defined manner via Ugi multicomponent reaction has not yet been studied. Herein, we report a synthetic strategy that enables both the modification of peptides as well as the generation of sequence-defined peptide–peptoid hybrid structures. Our synthetic methodology rests on the fusion of solid phase peptide synthesis with Ugi multicomponent reactions. We evidence that a diversity of chemical functionalities can be inserted into peptides or used in the design of peptide–peptoid hybrids exploiting a wide functional array including amines, carboxylic acids, hydrocarbons, carbohydrates as well as polymers, introducing a sequence-defined synthetic platform technology for precision peptoid hybrids