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Regeneration of articular cartilage remains challenging. The aim of this study was to increase the stability of pure bioactive glass (BG) scaffolds by means of solvent phase polymer infiltration and to maintain cell adherence on the glass struts. Therefore, BG scaffolds either pure or enhanced with three different amounts of poly(D-L-lactide-co-glycolide) (PLGA) were characterized in detail. Scaffolds were seeded with primary porcine articular chondrocytes (pACs) and human mesenchymal stem cells (hMSCs) in a dynamic long-term culture (35 days). Light microscopy evaluations showed that PLGA was detectable in every region of the scaffold. Porosity was greater than 70%. The biomechanical stability was increased by polymer infiltration. PLGA infiltration did not result in a decrease in viability of both cell types, but increased DNA and sulfated glycosaminoglycan (sGAG) contents of hMSCs-colonized scaffolds. Successful chondrogenesis of hMSC-colonized scaffolds was demonstrated by immunocytochemical staining of collagen type II, cartilage proteoglycans and the transcription factor SOX9. PLGA-infiltrated scaffolds showed a higher relative expression of cartilage related genes not only of pAC-, but also of hMSC-colonized scaffolds in comparison to the pure BG. Based on the novel data, our recommendation is BG scaffolds with single infiltrated PLGA for cartilage tissue engineering.

Quantum simulation on emerging quantum hardware is a topic of intense interest. While many studies focus on computing ground-state properties or simulating unitary dynamics of closed systems, open quantum systems are an interesting target of study owing to their ubiquity and rich physical behavior. However, their nonunitary dynamics are also not natural to simulate on digital quantum devices. Here, we report algorithms for the digital quantum simulation of the dynamics of open quantum systems governed by a Lindblad equation using adaptations of the quantum imaginary–time evolution algorithm. We demonstrate the algorithms on IBM Quantum’s hardware with simulations of the spontaneous emission of a two-level system and the dissipative transverse field Ising model. Our work advances efforts to simulate the dynamics of open quantum systems on quantum hardware.

Anti-citrullinated protein autoantibodies (ACPA) precede the onset of clinical and subclinical rheumatoid arthritis (RA). ACPA are frequently generated in further chronic inflammatory diseases, e.g. chronic obstructive pulmonary disease, lupus, periodontitis (PD), characterized by citrullination and mucosal as well as systemic autoimmunity against citrullinated proteins. PD is of particular interest, as it exhibits two sources of citrullination, namely peptidylarginine deiminase 4 (PAD4) of periodontal neutrophils and neutrophil extracellular traps (NETs) as well as the PAD of Porphyromonas gingivalis (PPAD). Whereas the PAD4-citrullinated host peptides and/or proteins occur physiologically, PPAD-citrullinated ones appear under pathological conditions as neo-antigens. Frequently, the oral pathogens P. gingivalis and A. actinomycetemcomitans directly and indirectly participate in synovitis in RA, providing topical citrullination: P. gingivalis via PPAD and A. actinomycetemcomitans via leukotoxin A-mediated ROS-independent NET formation. In addition, transient bacteraemia due to tooth brushing indicates the possibility that citrullinated peptides and/or proteins from periodontium regularly enter the blood circulation. In this way, the mucosal firewall is evaded and the systemic immune response against citrullinated peptides and/or proteins is facilitated. However, the role of swallowed PD-derived sludge for the induction of oral tolerance remains to be established. We hypothesize (I) PD-driven endotoxemia may increase the host responsiveness to autoantigens via TLR4 activation and (II) this participates in development and propagation of RA (III) circulating PD-derived bacterial DNA is taken up by phagocytes, activates TLR9, and thus increases the responsiveness to autoantigens.

Mo’orea, French Polynesia of the Society Islands archipelago is a highly isolated volcanic Pacific Island. It is vulnerable to invasion by introduced species due to this isolation in conjunction with its small size and disharmonic native biota. Falcataria moluccana is one such invader; since its introduction in the 1960s to reforest burned and eroded ridges it has established monodominant stands throughout the island. I studied the effects of this species on vegetation ecology, specifically native and non-native understory diversity, tree community dynamics, and species spread potential. Contrary to expectations, I found that native understory was able to persist despite ecosystem modifications caused by F. moluccana. However, the majority of native species present were post-disturbance taxa. Tree community analysis revealed that F. moluccana trees are able to grow to large sizes where other trees cannot, which suggests either niche differentiation or resource monopolization. Seedling count results indicate that this species may be enabling its spread through ecosystem modification, specifically the infusion of nitrogen into the environment via leaf litter. Future studies on long-term dynamics of F. moluccana stands combined with germination studies, soil chemistry analyses, and resource availability surveys would be beneficial to future conservation efforts on Mo’orea.

High electron mobility transistors are widely used as microwave amplifiers owing to their low microwave noise figure. Electronic noise in these devices is typically modeled by noise sources at the gate and drain. While consensus exists regarding the origin of the gate noise, that of drain noise is a topic of debate. Here, we report a theory of drain noise as a type of partition noise arising from real-space transfer of hot electrons from the channel to the barrier. The theory accounts for the magnitude and dependencies of the drain temperature and suggests strategies to realize devices with lower noise figure. [ABSTRACT FROM AUTHOR]

Thermal metamaterials have emerged as one of the latest research topics in applied science due to breakthrough advantages in modifying conductive heat flux. An acoustic Bragg reflector (ABR), composed of alternating arrays of two materials with contrasting acoustic impedances, is anticipated to coherently manipulate the transport properties of thermally important phonon branches by attaining interface roughness close to the monoatomic scale. However, there is a lack of research on how a narrow portion of the phononic band of a particular ABR can be extended to cover the entire thermal spectrum. Here, we report a modeling study of thermal transport using ABR, representatively based on GaAs/AlAs, GaN/AlN, or HfO 2 / SiO 2 superlattices. Our calculations show that the anisotropy of thermal conductivity in HfO 2 / SiO 2 can be significantly improved by tandemizing four different ABR layers, thus approaching the theoretically anticipated values based on monolayered materials. This work demonstrates how the tandem ABR can expand forbidden phononic bands beyond that occupied by a single ABR and proposes a practical strategy for realizing spectrally functionalized thermal properties from compound semiconductor materials that can be directly integrated into the existing device fabrication processes. [ABSTRACT FROM AUTHOR]

We demonstrate that the thermal boundary conductivity (TBC) between graphene and GaN-based light-emitting diodes (LEDs) can be manipulated through thermal annealing, which is verified by measuring the acoustic phonons after reflection at the interface. Thermal annealing affects the interfacial morphology as evaluated by both the Raman spectra and the spatial profile of the graphene wrinkles in atomic force microscopy. By tracing the phase of ultrafast acoustic oscillations on the basis of the pump-probe scheme, we extract the phonon reflection coefficient at the interface as a function of annealing temperatures up to 400 ° C. Specifically, the phase shift of transient phononic oscillations at the graphene/LED interface conveys the photoelastic response during the phonon transfer process and can be used for extracting the interfacial coupling rate, which is strongly enhanced around ≈ 200 ° C. By incorporating the heat capacity and the interfacial coupling constants into TBC, along with analytical modeling based on the phonon reflection coefficients, we show that the TBC increases with the minimized surface roughness of graphene side at 200 ° C. This new comprehensive TBC extraction scheme could spark further discussion on improving the heat dissipation of LEDs. [ABSTRACT FROM AUTHOR]

Background: Vascular corrosion casting is an old method that has found application by anatomists for a long time. Initially, the viscosity of casting media was very high and thus the technique failed to cast the entire circulatory system from the arterial injection site through small arteries, arterioles, capillaries, venules, small veins and caval veins. Casting media soon were improved and thus enabled casting of the entire circulatory system. Examination of these vascular casts under the light microscope does not allow a thorough analysis with high resolution. Only when in 1971 Murakami applied Scanning Electron Microscopy SEM. to study vascular corrosion casts a breakthrough was achieved and for the first time, microvascular networks, too, were able to be analysed with a spatial resolution high enough to study the surface of the casts also termed injection replicas. and a depth of focus high enough to examine a large field of view enabling to reliably trace individual vessels either over very short or over extremely long distances. Scanning electron microscopy SEM. is a tool with great potential for morphological research. The images generated via SEM have great resolution and a high depth of focus, which gives SEM micrographs pseudo three-dimensionality. Adversely, the high depth of focus prevents accurate dimensional or spatial measurements of imaged microstructures from either the SEM video-display, printed micrographs or from photonegatives. Macroscopic objects are viewed close up using binocular vision. Binocular vision is also used in microscopy where stereophotogrammetry and related techniques applying stereo paired images, and a variety of hardware tools calculate the third dimension z-coordinate. using the parallax. Morphometric SEM 3D analysis is currently used to analyse i. the geometry of microvascular trees in terms of vascular parameters i.e., diameters, interbranching distances, branching angles and intervascular distances. and ii. to determine bifurcation indices, asymmetry and area ratios given in arterial bifurcations respectively in venous mergings. Moreover, it allows to generate anaglyphic 3D images and to calculate optimality principles underlying the construction and maintenance of such delicate vascular networks i.e. principles of minimal lumen volume, minimal pumping power, minimal lumen surface and minimal endothelial shear force. Aim: The main goal of the method is to characterize microvascular networks in human and animal tissues in order to demonstrate their anatomical situations and to reflect onto their physiological conditions. These methods enable not only to qualitatively describe but also to quantitatively explore the microvascularisation by means of three-dimensional morphometry and thus to compare different developmental stages and progress of disease. Conclusions: The combination of the techniques described above allows a thorough study of microvascular networks in healthy- and pathologic tissues and organs. This enables i. to enhance the knowledge of vascular- / anatomical situations and development, ii. to compare the physiological conditions in health and different pathologies and iii. to gain insights and to develop therapeutical strategies in various clinical pictures, which are critically dependent on a proper functioning vascularization. [ABSTRACT FROM AUTHOR]

Pathogenic bacteria recognize environmental cues to vary gene expression for host adaptation. Moving from ambient to host temperature, Yersinia enterocolitica responds by immediately repressing flagella synthesis and inducing the virulence plasmid (pYV)-encoded type III secretion system. In contrast, shifting from host to ambient temperature requires 2.5 generations to restore motility, suggesting a link to the cell cycle. We hypothesized that differential DNA methylation contributes to temperature-regulated gene expression. We tested this hypothesis by comparing single-molecule real-time (SMRT) sequencing of Y. enterocolitica DNA from cells growing exponentially at 22 °C and 37 °C. The inter-pulse duration ratio rather than the traditional QV scoring was the kinetic metric to compare DNA from cells grown at each temperature. All 565 YenI restriction sites were fully methylated at both temperatures. Among the 27,118 DNA adenine methylase (Dam) sites, 42 had differential methylation patterns, while 17 remained unmethylated regardless of the temperature. A subset of the differentially methylated Dam sites localized to promoter regions of predicted regulatory genes including LysR-type and PadR-like transcriptional regulators and a cyclic-di-GMP phosphodiesterase. The unmethylated Dam sites localized with a bias to the replication terminus, suggesting they were protected from Dam methylase. No cytosine methylation was detected at Dcm sites. [ABSTRACT FROM AUTHOR]

Microwave loss in superconducting TiN films is attributed to two-level systems in various interfaces arising in part from oxidation and microfabrication-induced damage. Atomic layer etching (ALE) is an emerging subtractive fabrication method which is capable of etching with angstrom-scale etch depth control and potentially less damage. However, while ALE processes for TiN have been reported, they either employ HF vapor, incurring practical complications, or the etch rate lacks the desired control. Furthermore, the superconducting characteristics of the etched films have not been characterized. Here, we report an isotropic plasma-thermal TiN ALE process consisting of sequential exposures to molecular oxygen and an SF 6 /H 2 plasma. For certain ratios of SF 6 :H 2 flow rates, we observe selective etching of TiO 2 over TiN, enabling self-limiting etching within a cycle. Etch rates were measured to vary from 1.1 Å/cycle at 150 ° C to 3.2 Å/cycle at 350 ° C using ex situ ellipsometry. We demonstrate that the superconducting critical temperature of the etched film does not decrease beyond that expected from the decrease in film thickness, highlighting the low-damage nature of the process. These findings have relevance for applications of TiN in microwave kinetic inductance detectors and superconducting qubits. [ABSTRACT FROM AUTHOR]

Talking together about their teaching in very different fields--philosophy, art, movement education/somatics--the authors realized that there was something startlingly similar and valuable about what they were trying to teach and that it was somehow expressed in the elusive but crucial "how" of their actual teaching. How they teach is never neutral. It suggests to their students ways of relating to themselves, their own experiences, interests, hopes, problems, their peers, authorities, knowledge--the world. For three years, the authors discussed what they actually do when teaching: describing, questioning, reflecting; sharing writing; discerning recurrent themes as they observed characteristics, qualities, and, importantly, values. What, they kept asking, is the why that informs the how of the way they teach? They agreed that, whatever science may contribute to it, teaching itself is an art, often--when purposefully focused in the unique present moment, on the presence of these, and no other, students--an improvisatory one. This relational art in the details of actual practices suggests that values are in play, including respect and care for individuals; weighting the unique over the standard; embracing the present rather than reducing it to no more than a means; enhancing autonomy by taking experiences as well as authoritative sources seriously. Such enacted values reclaim learning as a heightening experience of life rather than merely or primarily preparation for it.