In order to prevent hemorrhage during surgical procedures, a wide range of hemostatic agents have been developed. However, their efficacy is variable; hemostatic devices that use bioactive components ...to accelerate coagulation are dependent on natural sources, which limits reproducibility. Hybrid devices in which chain-end reactive poly(ethylene glycol) is employed as active component sometimes suffer from irregular cross-linking and dissolution of the polar PEG when blood flow is substantial. Herein, we describe a synthetic, nonbioactive hemostatic product by coating N-hydroxysuccinimide ester (NHS)-functional poly(2-oxazoline)s (POx-NHS) onto gelatin patches, which acts by formation of covalent cross-links between polymer, host blood proteins, gelatin and tissue to seal the wound site and prevent hemorrhage during surgery. We studied different process parameters (including polymer, carrier, and coating technique) in direct comparison with clinical products (Hemopatch and Tachosil) to obtain deeper understanding of this class of hemostatic products. In this work, we successfully prove the hemostatic efficacy of POx-NHS as polymer powders and coated patches both in vitro and in vivo against Hemopatch and Tachosil, demonstrating that POx-NHS are excellent candidate polymers for the development of next generation hemostatic patches.
Loss-induced suppression and revival of lasing Peng, B.; Özdemir, Ş. K.; Rotter, S. ...
Science (American Association for the Advancement of Science),
10/2014, Letnik:
346, Številka:
6207
Journal Article
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Controlling and reversing the effects of loss are major challenges in optical systems. For lasers, losses need to be overcome by a sufficient amount of gain to reach the lasing threshold. In this ...work, we show how to turn losses into gain by steering the parameters of a system to the vicinity of an exceptional point (EP), which occurs when the eigenvalues and the corresponding eigenstates of a system coalesce. In our system of coupled microresonators, EPs are manifested as the loss-induced suppression and revival of lasing. Below a critical value, adding loss annihilates an existing Raman laser. Beyond this critical threshold, lasing recovers despite the increasing loss, in stark contrast to what would be expected from conventional laser theory. Our results exemplify the counterintuitive features of EPs and present an innovative method for reversing the effect of loss.
The development of bone glues based on bone‐adhesive hydrogels to allow for facile bone fracture fixation remains a major challenge. Herein, dual crosslinked hydrogels that combine tunable stiffness, ...ductility, and self‐healing capacity are successfully synthesized. The resulting double network hydrogel is formed by chemical crosslinking of N‐hydroxysuccinimide‐functionalized poly(2‐oxazoline)s(POx‐NHS)"?> with amine‐functionalized poly(2‐oxazoline)s, and physical crosslinking of alendronate‐functionalized poly(2‐oxazoline)s (POx‐Ale) with calcium ions in solution. The use of an excess of alendronate‐functionalized POx‐Ale polymers also ensures affinity toward calcium cations in the mineral phase of bone, thereby rendering these hydrogels adhesive to bone. The mechanical and bone‐adhesive properties of these novel hydrogels are superior to commercially available fibrin sealants. Moreover, hydrogels retain their bone‐adhesive properties under wet conditions. Although the dual crosslinked hydrogels swell considerably, they are stable upon immersion in phosphate‐buffered saline (up to 12 d) and even in ethylenediaminetetraacetic acid solution. The enhanced mechanical and bone‐adhesive properties of these hydrogels, as well as their in vitro stability, indicate that they have much application potential as bone‐adhesive glues.
Dual crosslinked hydrogels that combine robust mechanical properties with bone adhesive behavior under wet conditions as well as in vitro stability are successfully synthesized. This novel bone adhesive hydrogel platform provides a strong basis for further development of bone adhesive glues to allow for facile bone fracture fixation.
In the cold dark matter cosmology, the baryonic components of galaxies-stars and gas-are thought to be mixed with and embedded in non-baryonic and non-relativistic dark matter, which dominates the ...total mass of the galaxy and its dark-matter halo. In the local (low-redshift) Universe, the mass of dark matter within a galactic disk increases with disk radius, becoming appreciable and then dominant in the outer, baryonic regions of the disks of star-forming galaxies. This results in rotation velocities of the visible matter within the disk that are constant or increasing with disk radius-a hallmark of the dark-matter model. Comparisons between the dynamical mass, inferred from these velocities in rotational equilibrium, and the sum of the stellar and cold-gas mass at the peak epoch of galaxy formation ten billion years ago, inferred from ancillary data, suggest high baryon fractions in the inner, star-forming regions of the disks. Although this implied baryon fraction may be larger than in the local Universe, the systematic uncertainties (owing to the chosen stellar initial-mass function and the calibration of gas masses) render such comparisons inconclusive in terms of the mass of dark matter. Here we report rotation curves (showing rotation velocity as a function of disk radius) for the outer disks of six massive star-forming galaxies, and find that the rotation velocities are not constant, but decrease with radius. We propose that this trend arises because of a combination of two main factors: first, a large fraction of the massive high-redshift galaxy population was strongly baryon-dominated, with dark matter playing a smaller part than in the local Universe; and second, the large velocity dispersion in high-redshift disks introduces a substantial pressure term that leads to a decrease in rotation velocity with increasing radius. The effect of both factors appears to increase with redshift. Qualitatively, the observations suggest that baryons in the early (high-redshift) Universe efficiently condensed at the centres of dark-matter haloes when gas fractions were high and dark matter was less concentrated.
A library of poly(2-oxazoline)s functionalized with controllable amounts of alendronate, hydroxyl, and carboxylic acid side groups was successfully synthesized to create novel polymers with tunable ...affinity for calcium cations. The affinity of alendronate-containing polymers for calcium cations was quantified using isothermal titration calorimetry. Thermodynamic measurements revealed that the Ca2+-binding affinity of these polymers increased linearly with the amount of alendronate functionalization, up to values (K Ca 2+ = 2.4 × 105 M–1) that were about 120-fold higher than those for previously reported polymers. The calcium-binding capacity of alendronate-functionalized poly(2-oxazoline)s was exploited to form robust hydrogel networks cross-linked using reversible physical bonds. Oscillatory rheology showed that these hydrogels recovered more than 100% of their initial storage modulus after severe network destruction. The versatile synthesis of alendronate-functionalized polymers and their strong and tunable affinity for calcium cations render these polymers promising candidates for various biomedical applications.
Cultured cell lines are the workhorse of cancer research, but the extent to which they recapitulate the heterogeneity observed among malignant cells in tumors is unclear. Here we used multiplexed ...single-cell RNA-seq to profile 198 cancer cell lines from 22 cancer types. We identified 12 expression programs that are recurrently heterogeneous within multiple cancer cell lines. These programs are associated with diverse biological processes, including cell cycle, senescence, stress and interferon responses, epithelial-mesenchymal transition and protein metabolism. Most of these programs recapitulate those recently identified as heterogeneous within human tumors. We prioritized specific cell lines as models of cellular heterogeneity and used them to study subpopulations of senescence-related cells, demonstrating their dynamics, regulation and unique drug sensitivities, which were predictive of clinical response. Our work describes the landscape of heterogeneity within diverse cancer cell lines and identifies recurrent patterns of heterogeneity that are shared between tumors and specific cell lines.
symmetric quantum field theory Bender, C M
Journal of physics. Conference series,
09/2020, Letnik:
1586, Številka:
1
Journal Article
Recenzirano
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\({\mathscr{PT}}\)-symmetric quantum theory began with an analysis of the strange-looking non-Hermitian Hamiltonian H = p 2 + x (ix)ε. This Hamiltonian is \({\mathscr{PT}}\) symmetric and the ...eigenvalues Hamiltonian are discrete, real, and positive when ε ≥ 0. In this talk we describe the properties of the corresponding quantum-field-theoretic Hamiltonian \(H=\frac{1}{2}{(\nabla \phi )}^{2}+\frac{1}{2}{\phi }^{2}{(i\phi )}^{\varepsilon }\) in D-dimensional spacetime, where φ is a pseudoscalar field. We show how to calculate all of the Green’s functions as series in powers of ε directly from the Euclidean partition function. We derive exact finite expressions for the vacuum energy density, the renormalized mass, and the connected n-point Green’s functions for all n 0 ≤ D ≤ 2. For D ≥ 2 the one-point Green’s function and the renormalized mass become infinite, but perturbative renormalization can be performed. The beautiful spectral properties of \({\mathscr{PT}}\)-symmetric quantum mechanics appear to persist in \({\mathscr{PT}}\)-symmetric quantum field theory.
PT-symmetric quantum field theory Bender, C M
Journal of physics. Conference series,
08/2020, Letnik:
1586, Številka:
1
Journal Article
Recenzirano
Odprti dostop
PT-symmetric quantum theory began with an analysis of the strange-looking non-Hermitian Hamiltonian H = p2 + x (ix)ε. This Hamiltonian is PT symmetric and the eigenvalues Hamiltonian are discrete, ...real, and positive when ε ≥ 0. In this talk we describe the properties of the corresponding quantum-field-theoretic Hamiltonian H=12(∇ϕ)2+12ϕ2(iϕ)ε in D-dimensional spacetime, where φ is a pseudoscalar field. We show how to calculate all of the Green's functions as series in powers of ε directly from the Euclidean partition function. We derive exact finite expressions for the vacuum energy density, the renormalized mass, and the connected n-point Green's functions for all n 0 ≤ D ≤ 2. For D ≥ 2 the one-point Green's function and the renormalized mass become infinite, but perturbative renormalization can be performed. The beautiful spectral properties of PT-symmetric quantum mechanics appear to persist in PT-symmetric quantum field theory.
To create a novel generation of barrier membranes with bone-adhesive properties, three-component membranes were successfully developed using a solvent-free approach by combining an occlusive ...polyester backing layer with a bone-adhesive fibrous gelatin carrier impregnated with calcium-binding alendronate-functionalized poly(2-oxazoline)s (POx-Ale). The mechanical properties of these novel membranes were similar to other commercially available barrier membranes. In contrast, the adhesion of our membranes towards bone was by far superior (
i.e.
62-fold) compared to conventional commercially available Bio-Gide® membranes. Moreover, alendronate-functionalized membranes retained their bone-adhesive properties under wet conditions in phosphate-buffered saline (PBS) solutions with and without collagenase. Finally, the
in vitro
degradation of the membranes was studied by monitoring their weight loss upon immersion in PBS solutions with and without collagenase. The membranes degraded in a sustained manner, which was accelerated by the presence of collagenase due to enzymatic degradation of the carrier. In conclusion, our results show that surface functionalization of barrier membranes with alendronate moieties renders them adhesive to bone. As such, the biomaterials design strategy presented herein opens up new avenues of research on bone-adhesive membranes for guided bone regeneration.
Novel bone-adhesive barrier membranes were successfully developed using a solvent-free approach by combining an occlusive polyester backing layer with a gelatin carrier impregnated with calcium-binding alendronate-functionalized poly(2-oxazoline)s.
OBJECTIVE: The purpose of this study was to compare psychosocial functioning in patients with schizotypal, borderline, avoidant, or obsessive-compulsive personality disorder and patients with major ...depressive disorder and no personality disorder. METHOD: Patients (N=668) were recruited by the four clinical sites of the Collaborative Longitudinal Personality Disorders Study. The carefully diagnosed study groups were compared on an array of domains of psychosocial functioning, as measured by the Longitudinal Interval Follow-Up Evaluation-Baseline Version and the Social Adjustment Scale. RESULTS: Patients with schizotypal personality disorder and borderline personality disorder were found to have significantly more impairment at work, in social relationships, and at leisure than patients with obsessive-compulsive personality disorder or major depressive disorder; patients with avoidant personality disorder were intermediate. These differences were found across assessment modalities and remained significant after covarying for demographic differences and comorbid axis I psychopathology. CONCLUSIONS: Personality disorders are a significant source of psychiatric morbidity, accounting for more impairment in functioning than major depressive disorder alone.
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