Synthesis and characterization of mesoporous zirconia nanocomposite using self-assembled block copolymer template

Mesoporous zirconia has properties such as high surface area, uniform pore size distribution, and large pore volume, thus attracting great attention from the research community. Self-assembled structures have been used as directing agents to synthesize mesoporous zirconia. Here, we investigated the use of block copolymers conjugated to cationic biomolecules such as lysozyme, as well as cationic block copolymers as templates to synthesize mesoporous zirconia in completely aqueous media. Based on the Pluronic-lysozyme conjugate template, we further studied the effects of preparation conditions, including calcination temperature, precursor concentration, and precipitating pH. Several technics such as TGA, XRD, TEM, and N2 sorption were employed to characterize the zirconia samples. The results showed that tetragonal zirconia started to form after 300&degC calcination and became fully crystallized after 500&degC, grew larger when heated to higher temperatures, and began to form monoclinic phase after 900&degC calcination. Our modified templates enhanced the thermal stability and increased the surface area of zirconia samples. The results also indicated that low precursor concentration and alkali media helped to decrease the zirconia particle size as well as increase the specific surface area. The surface area of the as-synthesized zirconia sample exhibited an increase before 500&degC and a decrease after that, the highest specific surface area, 348 m2/g, achieved after 500&degC calcination which was obtained using 0.08mol/L precursor at pH=10

Jamming Suppression Via Resource Hopping in High-Mobility OTFS-SCMA Systems

This letter studies the mechanism of uplink multiple access and jamming suppression in an OTFS system. Specifically, we propose a novel resource hopping mechanism for orthogonal time frequency space (OTFS) systems with delay or Doppler partitioned sparse code multiple access (SCMA) to mitigate the effect of jamming in controlled multiuser uplink. We analyze the non-uniform impact of classic jamming signals such as narrowband interference (NBI) and periodic impulse noise (PIN) in delay-Doppler (DD) domain on OTFS systems. Leveraging turbo equalization, our proposed hopping method demonstrates consistent BER performance improvement under jamming over conventional OTFS-SCMA systems compared to static resource allocation schemes

Synthesis and characterization of mesoporous zirconia nanocomposite using self-assembled block copolymer template

Mesoporous zirconia has properties such as high surface area, uniform pore size distribution, and large pore volume, thus attracting great attention from the research community. Self-assembled structures have been used as directing agents to synthesize mesoporous zirconia. Here, we investigated the use of block copolymers conjugated to cationic biomolecules such as lysozyme, as well as cationic block copolymers as templates to synthesize mesoporous zirconia in completely aqueous media. Based on the Pluronic-lysozyme conjugate template, we further studied the effects of preparation conditions, including calcination temperature, precursor concentration, and precipitating pH. Several technics such as TGA, XRD, TEM, and N2 sorption were employed to characterize the zirconia samples. The results showed that tetragonal zirconia started to form after 300&degC calcination and became fully crystallized after 500&degC, grew larger when heated to higher temperatures, and began to form monoclinic phase after 900&degC calcination. Our modified templates enhanced the thermal stability and increased the surface area of zirconia samples. The results also indicated that low precursor concentration and alkali media helped to decrease the zirconia particle size as well as increase the specific surface area. The surface area of the as-synthesized zirconia sample exhibited an increase before 500&degC and a decrease after that, the highest specific surface area, 348 m2/g, achieved after 500&degC calcination which was obtained using 0.08mol/L precursor at pH=10.</p

OTFS signaling for SCMA with coordinated multi-point vehicle communications

This paper investigates an uplink coordinated multi-point (CoMP) coverage scenario, in which multiple mobile users are grouped for sparse code multiple access (SCMA), and served by the remote radio head (RRH) in front of them and the RRH behind them simultaneously. We apply orthogonal time frequency space (OTFS) modulation for each user to exploit the degrees of freedom arising from both the delay and Doppler domains. As the signals received by the RRHs in front of and behind the users experience respectively positive and negative Doppler frequency shifts, our proposed OTFS-based SCMA (OBSCMA) with CoMP system can effectively harvest extra Doppler and spatial diversity for better performance. Based on maximum likelihood (ML) detector, we analyze the single-user average bit error rate (ABER) bound as the benchmark of the ABER performance for our proposed OBSCMA with CoMP system. We also develop a customized Gaussian approximation with expectation propagation (GAEP) algorithm for multi-user detection and propose efficient algorithm structures for centralized and decentralized detectors. Our proposed OBSCMA with CoMP system leads to stronger performance than the existing solutions. The proposed centralized and decentralized detectors exhibit effective reception and robustness under channel state information uncertainty.The work of Qinwen Deng and Zhi Ding was supported by the National Science Foundation under Grant 2029027. This work was supported by the RIE2020 Industry Alignment Fund–Industry Collaboration Projects (IAFICP) Funding Initiative, and cash and in-kind contribution from the industry partner(s)

Dnmt3b ablation affects fracture repair process by regulating apoptosis

Abstract Purpose Previous studies have shown that DNA methyltransferase 3b (Dnmt3b) is the only Dnmt responsive to fracture repair and Dnmt3b ablation in Prx1-positive stem cells and chondrocyte cells both delayed fracture repair. Our study aims to explore the influence of Dnmt3b ablation in Gli1-positive stem cells in fracture healing mice and the underlying mechanism. Methods We generated Gli1-CreERT2; Dnmt3bflox/flox (Dnmt3b Gli1ER ) mice to operated tibia fracture. Fracture callus tissues of Dnmt3b Gli1ER mice and control mice were collected and analyzed by X-ray, micro-CT, biomechanical testing, histopathology and TUNEL assay. Results The cartilaginous callus significantly decrease in ablation of Dnmt3b in Gli1-positive stem cells during fracture repair. The chondrogenic and osteogenic indicators (Sox9 and Runx2) in the fracture healing tissues in Dnmt3b Gli1ER mice much less than control mice. Dnmt3b Gli1ER mice led to delayed bone callus remodeling and decreased biomechanical properties of the newly formed bone during fracture repair. Both the expressions of Caspase-3 and Caspase-8 were upregulated in Dnmt3b Gli1ER mice as well as the expressions of BCL-2. Conclusions Our study provides an evidence that Dnmt3b ablation Gli1-positive stem cells can affect fracture healing and lead to poor fracture healing by regulating apoptosis to decrease chondrocyte hypertrophic maturation

Delivery of dental pulp stem cells by an injectable ROS-responsive hydrogel promotes temporomandibular joint cartilage repair via enhancing anti-apoptosis and regulating microenvironment

Temporomandibular joint (TMJ) cartilage repair poses a considerable clinical challenge, and tissue engineering has emerged as a promising solution. In this study, we developed an injectable reactive oxygen species (ROS)-responsive multifunctional hydrogel (RDGel) to encapsulate dental pulp stem cells (DPSCs/RDGel in short) for the targeted repair of condylar cartilage defect. The DPSCs/RDGel composite exhibited a synergistic effect in the elimination of TMJ OA (osteoarthritis) inflammation via the interaction between the hydrogel component and the DPSCs. We first demonstrated the applicability and biocompatibility of RDGel. RDGel encapsulation could enhance the anti-apoptotic ability of DPSCs by inhibiting P38/P53 mitochondrial apoptotic signal in vitro. We also proved that the utilization of DPSCs/RDGel composite effectively enhanced the expression of TMJOA cartilage matrix and promoted subchondral bone structure in vivo. Subsequently, we observed the synergistic improvement of DPSCs/RDGel composite on the oxidative stress microenvironment of TMJOA and its regulation and promotion of M2 polarization, thereby confirmed that M2 macrophages further promoted the condylar cartilage repair of DPSCs. This is the first time application of DPSCs/RDGel composite for the targeted repair of TMJOA condylar cartilage defects, presenting a novel and promising avenue for cell-based therapy

Amygdalin Promotes Fracture Healing through TGF-β/Smad Signaling in Mesenchymal Stem Cells

Chondrogenesis and subsequent osteogenesis of mesenchymal stem cells (MSCs) and angiogenesis at injured sites are crucial for bone fracture healing. Amygdalin, a cyanogenic glycoside compound derived from bitter apricot kernel, has been reported to inhibit IL-1β-induced chondrocyte degeneration and to stimulate blood circulation, suggesting a promising role of amygdalin in fracture healing. In this study, tibial fractures in C57BL/6 mice were treated with amygdalin. Fracture calluses were then harvested and subjected to radiographic, histological, and biomechanical testing, as well as angiography and gene expression analyses to evaluate fracture healing. The results showed that amygdalin treatment promoted bone fracture healing. Further experiments using MSC-specific transforming growth factor- (TGF-) β receptor 2 conditional knockout (KO) mice (Tgfbr2Gli1-Cre) and C3H10 T1/2 murine mesenchymal progenitor cells showed that this effect was mediated through TGF-β/Smad signaling. We conclude that amygdalin could be used as an alternative treatment for bone fractures