Softness and firmness are seemingly incompatible traits that synergize to create the unique soft-yet-firm tactility of living tissues pursued in soft robotics, wearable electronics, and plastic ...surgery. This dichotomy is particularly pronounced in tissues such as fat that are known to be both ultrasoft and ultrafirm. However, synthetically replicating this mechanical response remains elusive since ubiquitously employed soft gels are unable to concurrently reproduce tissue firmness. We have addressed the tissue challenge through the self-assembly of linear–bottlebrush–linear (LBL) block copolymers into thermoplastic elastomers. This hybrid molecular architecture delivers a hierarchical network organization with a cascade of deformation mechanisms responsible for initially low moduli followed by intense strain-stiffening. By bridging the firmness gap between gels and tissues, we have replicated the mechanics of fat, fetal membrane, spinal cord, and brain tissues. These solvent-free, nonleachable, and tissue-mimetic elastomers also show enhanced biocompatibility as demonstrated by cell proliferation studies, all of which are vital for the safety and longevity of future biomedical devices.
The ideas of the Protestant Reformation, followed by the European Enlightenment, had a profound and long-lasting impact on Russia’s church and society in the eighteenth century. Though the ...traditional Orthodox Church was often assumed to have been hostile toward outside influence, Andrey V. Ivanov’s study argues that the institution in fact embraced many Western ideas, thereby undergoing what some observers called a religious revolution.
Embedded with lively portrayals of historical actors and vivid descriptions of political details, A Spiritual Revolution is the first large-scale effort to fully identify exactly how Western progressive thought influenced the Russian Church. These new ideas played a foundational role in the emergence of the country as a modernizing empire and the rise of the Church hierarchy as a forward-looking agency of institutional and societal change. Ivanov addresses this important debate in the scholarship on European history, firmly placing Orthodoxy within the much wider European and global continuum of religious change.
The Arctic Circumpolar Boundary Current (ACBC) transports a vast amount of mass and heat around cyclonic gyres of the deep basins, acting as a narrow, topographically-controlled flow, confined to the ...continental margins. Current observations during 2002–2011 at seven moorings along the major Atlantic Water (AW) pathway, complemented by an extensive collection of measured temperatures and salinities as well as results of state-of-the-art numerical modeling, have been used to examine the spatial structure and temporal variability of the ACBC within the Eurasian Basin (EB). These observations and modeling results suggest a gradual, six-fold decrease of boundary current speed (from 24 to 4cm/s) on the route between Fram Strait and the Lomonosov Ridge, accompanied by a transformation of the vertical flow structure from mainly barotropic in Fram Strait to baroclinic between the area north of Spitsbergen and the central Laptev Sea continental slope. The relative role of density-driven currents in maintaining AW circulation increases with the progression of the ACBC eastward from Fram Strait, so that baroclinic ACBC forcing dominates over the barotropic in the eastern EB. Mooring records have revealed that waters within the AW and the cold halocline layers circulate in roughly the same direction in the eastern EB. The seasonal signal, meanwhile, is the most powerful mode of variability in the EB, contributing up to ~70% of the total variability in currents (resolved by moorings records) within the eastern EB. Seasonal signal amplitudes for current speed and AW temperature both decrease with the eastward progression of AW flow from source regions, and demonstrate strong interannual modulation. In the 2000s, the state of the EB (e.g., circulation pattern, thermohaline conditions, and freshwater balance) experienced remarkable changes. Results showing anomalous circulation patterns for an extended period of 30 months in 2008–2010 for the eastern EB, and a two-core AW temperature structure that emerged in this region of the Arctic Ocean in the most recent decade, suggest a shift of the EB toward a new, more dynamic state. This also likely suggests that the EB interior will become more susceptible to future climate change. Evaluating properties of the ACBC, its temporal variability at time scales from a season to several years, and possible governing mechanisms, this study contributes to a better understanding of Arctic Ocean circulation.
•A six-fold decrease in boundary current speed (from 24 to 4cm/s) was registered on the along-slope route between Fram Strait and the Lomonosov Ridge.•Mooring observations show vertical coherence of flow in Atlantic Water and halocline layers in the Eurasian Basin.•In the eastern Eurasian Basin, amplitude of seasonal changes constitutes up to ~70% of the mean boundary current speed.•Prevailing anticyclonic (i.e., shallow-to-left) circulation was found for 2008–2010 in the eastern Eurasian Basin. The cause, we hypothesize, was the large-scale reconstruction of temperature and salinity fields.
Surface-enhanced Raman scattering (SERS) spectroscopy is a surface- or cavity-enhanced variant of Raman scattering spectroscopy that allows the detection of analytes with a sensitivity down to single ...molecules. This method involves the use of SERS-active surfaces or cavities capable of concentrating incident radiation into small mode volumes containing the analyte. Here, we have engineered an ultranarrow metal-dielectric nano-cavity out of a film of the receptor-binding domain (RBD) of SARS-CoV-2 spike (S) glycoprotein and a silver surface, held together by interaction between reduced protein sulfhydryl groups and silver. The concentration of light in this nano-cavity allows the label-free recording of the characteristic Raman spectra of protein samples smaller than 1 pg. This is sufficient for the ultrasensitive detection of viral protein antigens at physiologically relevant levels. Moreover, the protein SERS signal can be increased by several orders of magnitude by coating the RBD film with a nanometer-thick silver shell, thereby raising the cavity Q-factor. This ensures a sub-femtogram sensitivity of the viral antigen detection. A simple theoretical model explaining the observed additional enhancement of the SERS signal from the silver-coated protein is proposed. Our study is the first to obtain the characteristic Raman and SERS spectra of the RBD of S glycoprotein, the key SARS-CoV-2 viral antigen, directly, without the use of Raman-reporter molecules. Thus, our approach allows label-free recording of the characteristic spectra of viral antigens at concentrations orders of magnitude lower than those required for detecting the whole virus in biological media. This makes it possible to develop a high-performance optical detection method and conformational analysis of the pathogen and its variants.
The power of most of the enterobacterial O antigen types to provide robust protection against direct recognition of the cell surface by bacteriophage receptor-recognition proteins (RBP) has been ...recently recognized. The bacteriophages infecting O antigen producing strains of E. coli employ various strategies to tackle this nonspecific protection. T-even related phages, including RB49-like viruses, often have wide host ranges, being considered good candidates for use in phage therapy. However, the mechanisms by which these phages overcome the O antigen barrier remain unknown. We demonstrate here that RB49 and related phages Cognac49 and Whisky49 directly use certain types of O antigen as their primary receptors recognized by the virus long tail fibers (LTF) RBP gp38, so the O antigen becomes an attractant instead of an obstacle. Simultaneously to recognize multiple O antigen types, LTFs of each of these phages can bind to additional receptors, such as OmpA protein, enabling them to infect some rough strains of E. coli. We speculate that the mechanical force of the deployment of the short tail fibers (STF) triggered by the LTF binding to the O antigen or underneath of it, allows the receptor binding domains of STF to break through the O polysaccharide layer.
Hot-melt pressure-sensitive adhesives (HMPSAs) are used in applications from office supplies to biomedical adhesives. The major component in HMPSA formulations is thermoplastic elastomers, such as ...styrene-based block copolymers, that provide both mechanical integrity and moldability. Since neat polymer networks are unable to establish an adhesive bond, large quantities of plasticizers and tackifiers are added. These additives enhance the adhesive performance but complicate the phase behavior and property stability of the pressure-sensitive adhesive. Herein, we introduce an alternative additive-free approach to HMPSA design based on self-assembly of bottlebrush graft-copolymers, where side chains behave as softness, strength, and viscoelasticity mediators. These systems maintain moldability of conventional thermoplastic elastomers, while architecturally disentangled bottlebrush network strands empower several benefits such as extreme softness for substrate wetting, low melt viscosity for molding and 3D-printing, and a broad frequency range of viscoelastic responses for adhesion regulation within almost four orders of magnitude. The brush graft-copolymers implement five independently controlled architectural parameters to regulate the Rouse time, work of adhesion, and debonding mechanisms.
The process of formation of a Langmuir–Schaefer (LS) matrix based on a mixed monolayer of arachidic acid (AA) and 8 nm CdSe/CdS/ZnS quantum dots (QDs) stabilized by molecules of trioctylphosphine ...oxide (TOPO) was investigated. The change in the morphology, monolayer compressibility, and area per elementary cell of the created mixed monolayers, depending on the ratio of the components, was studied. It is shown that the change in the morphology of Langmuir–Blodgett (LB) monolayers begins to occur at a ratio between the number of QDs and AA molecules of 1:24. Dendrimeric structures with a thickness of the order of 30–40 nm appear in the mixed monolayer when LB film deposition was carried out above the collapse surface pressure of a Langmuir film from only TOPO-covered QDs. Information on the dependence of the morphology of such structures on the molar ratio of the components is necessary for the production of ordered 2D nanostructures containing 0D and 1D objects with quantum bonds. Such nanostructures can be used in nanoelectronic and optoelectronic devices as a sensitive sensor element. The obtained results would be relevant for any type of spherical shape nanoparticles.
Two new cerium(IV) phosphates were obtained: cerium(IV) hydroxidophosphate, Ce(OH)PO4, and cerium(IV) oxidophosphate, Ce2O(PO4)2, which were shown to complement the classes of isostructural compounds ...M(OH)PO4 and R2O(PO4)2, where M=Th, U and R=Th, U, Np, Zr. Ce2O(PO4)2 oxidophosphate is formed by elimination of H2O from the crystal structure of Ce(OH)PO4 during its thermal decomposition. The structures of Ce(OH)PO4 and Ce2O(PO4)2 are related to each other with the same Cmce space group and similar unit cell parameters (a=6.9691(3) Å, b=9.0655(4) Å, c=12.2214(4) Å, V=772.13(8) Å3, Z=8; a=7.0220(4) Å, b=8.9894(5) Å, c=12.544(1) Å, V=791.8(1) Å3, Z=4, respectively).
New compounds discovered: Two previously unknown cerium(IV) phosphates with similar structures, Ce(OH)PO4 and Ce2O(PO4)2, are discovered. Ce(OH)PO4 belongs to a very limited family of ceric basic salts. Ce2O(PO4)2 can be obtained by a gentle dehydration of Ce(OH)PO4.
The beginning of the twenty-first century witnessed novel breakthrough research directions in the life sciences, such as genomics, transcriptomics, translatomics, proteomics, metabolomics, and ...bioinformatics. A newly developed single-molecule approach addresses the physical and chemical properties and the functional activity of single (individual) biomacromolecules and viral particles. Within the alternative approach, the combination of "single-molecule approaches" is opposed to "omics approaches". This new approach is fundamentally unique in terms of its research object (a single biomacromolecule). Most studies are currently performed using postgenomic technologies that allow the properties of several hundreds of millions or even billions of biomacromolecules to be analyzed. This paper discusses the relevance and theoretical, methodological, and practical issues related to the development potential of a single-molecule approach using methods based on molecular detectors.
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