Tough, self-healing and injectable dynamic nanocomposite hydrogel based on gelatin and sodium alginate.

Biomacromolecules based injectable and self-healing hydrogels possessing high mechanical properties have widespread potential in biomedical field. However, dynamic features are usually inversely proportional to toughness. It is challenging to simultaneously endow these properties to the dynamic hydrogels. Here, we fabricated an injectable nanocomposite hydrogel (CS-NPs@OSA-l-Gtn) stimultaneously possessing excellent autonomous self-healing performance and high mechanical strength by doping chitosan nanoparticles (CS-NPs) into dynamic polymer networks of oxidized sodium alginate (OSA) and gelatin (Gtn) in the presence of borax. The synergistic effect of the multiple reversible interactions combining dynamic covalent bonds (i.e., imine bond and borate ester bond) and noncovalent interactions (i.e., electrostatic interaction and hydrogen bond) provide effective energy dissipation to endure high fatigue resistance and cyclic loading. The dynamic hydrogel exhibited excellent mechanical properties like maximum 2.43 MPa compressive strength, 493.91 % fracture strain, and 89.54 kJ/m3 toughness. Moreover, the integrated hydrogel after injection and self-healing could withstand 150 successive compressive cycles. Besides, the bovine serum albumin embedded in CS-NPs could be sustainably released from the nanocomposite hydrogel for 12 days. This study proposes a novel strategy to synthesize an injectable and self-healing hydrogel combined with excellent mechanical properties for designing high-strength natural carriers with sustained protein delivery.

External Pressure Affecting Dendrite Growth and Dissolution in Lithium Metal Batteries During Cycles.

Lithium (Li) metal has garnered significant attention as the preferred anode for high-energy lithium metal batteries. However, safety concerns arising from the growth of Li dendrites have hindered the advancement of Li metal batteries. In this study, we first elucidate the impact of external pressure and internal stress on dendrite growth and dissolution behavior of Li metal batteries during continuous charging-discharging cycles, employing a developed electrochemomechanical phase-field model. A typical parameter is defined to calculate the amount of dead Li that affects the electrochemical performance of Li metal batteries during multiple cycles. The underlying mechanisms of dendrites observed from in situ experiments are explained through the developed phase-field model. After charging/discharging, dendrites with a treelike structure yield a greater amount of dead Li compared to those with a needlelike configuration. Increasing the pressure appropriately can effectively reduce the growth points of dendrites and suppress the Li dendrite growth. Excessive pressure not only induces dendritic fractures that lead to the formation of dead Li but also undermines the battery performance. The accumulated internal stress might threaten the structural stability of the Li metal, thereby influencing the evolution of the Li dendrite morphology. A reasonable strategy is proposed to strike a balance between external pressure and the growth and dissolution of Li dendrites. These findings offer valuable insights into the judicious application of pressure to mitigate the advancement of electroplating reactions.

Dynamic and self-biodegradable polysaccharide hydrogel stores embryonic stem cell construct under ambient condition.

The proper microenvironment is critical for the storage and transportation of embryonic stem cells (ESCs). To mimic a dynamic 3D microenvironment as it exists in vivo and consider "off-the-shelf" availability reaching the destination, we proposed an alternative approach that allows for facile storage and transportation of stem cells in the form of ESCs-dynamic hydrogel construct (CDHC) under ambient conditions. To form CDHC, mouse embryonic stem cells (mESCs) were in-situ encapsulated within a polysaccharide-based dynamic and self-biodegradable hydrogel. After storing CDHC in a sterile and hermetic environment for 3 days and then transferring to a sealed vessel with fresh medium for another 3 days, the large and compact colonies retained a 90% survival rate and pluripotency. Furthermore, after transporting and arriving at the destination, the encapsulated stem cell could be automatically released from the self-biodegradable hydrogel. After continuous cultivation of 15 generations of retrieved cells, automatically released from the CDHC, the mESCs underwent 3D encapsulation, storage, transportation, release, and continuous long-term subculture; resumed colony forming capacity and pluripotency were revealed by stem cell markers both in protein and mRNA levels. We believe that the dynamic and self-biodegradable hydrogel provides a simple, cost-effective, and valuable tool for storing and transporting "ready-to-use" CDHC under ambient conditions, facilitating "off-the-shelf" availability and widespread applications.

Elucidating the Role of Rational Separator Microstructures in Guiding Dendrite Growth and Reviving Dead Li.

Li metal has attracted considerable attention as the preferred anode material for high-energy batteries. However, Li dendrites have limited the development of Li-metal batteries. Herein, the effects of tuning the porous separator microstructure (SM) for guiding Li dendrite growth and reviving dead Li are revealed using a mechano-electrochemical phase-field model. A strategy of guiding, instead of suppression, was applied to avoid disordered Li dendrite growth. By analyzing the effects of the number of layers, thickness, degree of staggered overlap in the separator, interlayer spacing, and porosity of SM on Li dendrite behavior, we discovered that applying a rationally designed SM can finely guide the Li nucleation and growth direction toward dense deposition. The revival of dead Li was also observed via an in situ experiment on Li dendrites. The reactivation of dead Li after it recontacts Li metal was verified. These findings not only provide fundamental information for the tuning of the SM but can also help better understand the dendrite growth of other alkali metal-ion batteries.

Calculations of Electronic Excitation Energies and Excess Electric Dipole Moments of Solvated p-Nitroaniline with the EOM-CCSD-PCM Method.

We present computational evidence utilizing vertical electronic excitation energies and the corresponding excess dipole moments of solvated p-nitroaniline ( pNA). The properties of interest are calculated by employing the equation of motion coupled cluster together with single and double excitations (EOM-CCSD). Solvent effects are included through the polarizable continuum model (PCM) with the state-specific (SS) formalism and the perturbation theory energy and density (PTED) approach. We examine the ground state equilibrium geometry of pNA in different environments to yield the symmetry of the stable conformer of solvated pNA is C s but is also C2 v. By employing the calculated vertical excitation energies overestimate experiment, our calculations confirm the consistency of the calculated excess dipole moments with comparable documented results. Lastly, specific to this study, dissimilar environmental models, such as the linear response (LR), and variants of the corrected linear response (cLR and cLR0) formalisms in the context of the EOM-CCSD-PCM-PTED, are assessed against those from the SS formalism.

[Investigation of reproductive organs of male children and juvenile of the Meng and the Han nationality in Chifeng area].

OBJECTIVES: To investigate the development and the health of reproductive organs of male children and juvenile between the Meng and the Han nationality in the Meng nationality area. METHODS: Male juvenile(4-18 years old) of the Meng nationality (n = 2,315) and the Han nationality (n = 2,832) were divided into four age groups. Height, weight, length and perimeter of penis, volume of left and right testis and reproductive organs illness were examined. RESULTS: In 13-18 years group, the developmental speed of reproductive organs was faster in Mongolia male juvenile than that in the Han nationality (P < 0.02). After 13 years old, the developmental speed of reproductive organs of male living in town is faster than that in the country (P < 0.05). Illness of male reproductive organs was common such as hernia, varicocle etc. CONCLUSIONS: There was difference of developmental status and the prevalence rate of reproductive organs of male children and juvenile between the Meng and the Han nationality.