A recent trend has emerged that involves myocardial injection of biomaterials, containing cells or acellular, following myocardial infarction (MI) to influence the remodeling response through both biological and mechanical effects. Despite the number of different materials injected in these approaches, there has been little investigation into the importance of material properties on therapeutic outcomes. This work focuses on the investigation of injectable hyaluronic acid (MeHA) hydrogels that have tunable mechanics and gelation behavior. Specifically, two MeHA formulations that exhibit similar degradation and tissue distribution upon injection but have differential moduli (∼8 versus ∼43 kPa) were injected into a clinically relevant ovine MI model to evaluate the associated salutary effect of intramyocardial hydrogel injection on the remodeling response based on hydrogel mechanics. Treatment with both hydrogels significantly increased the wall thickness in the apex and basilar infarct regions compared with the control infarct. However, only the higher-modulus (MeHA High) treatment group had a statistically smaller infarct area compared with the control infarct group. Moreover, reductions in normalized end-diastolic and end-systolic volumes were observed for the MeHA High group. This group also tended to have better functional outcomes (cardiac output and ejection fraction) than the low-modulus (MeHA Low) and control infarct groups. This study provides fundamental information that can be used in the rational design of therapeutic materials for treatment of MI.L eft ventricular (LV) remodeling caused by a myocardial infarction (MI) is responsible for almost 70% of the 5 million cases of heart failure that have occurred in the United States in recent years (1). Early infarct expansion or stretching has been associated with poor long-term prognosis (2-4) and has been identified as the mechanical phenomenon that initiates and sustains the process of adverse post-MI LV remodeling that leads to heart failure (5-10). Infarct expansion causes abnormal stress distribution in myocardial regions outside the infarction, especially in the adjacent borderzone region, putting this region at a mechanical disadvantage. With time, increased regional stress is the impetus for several maladaptive biologic processes, such as myocyte apoptosis and matrix metalloproteinase activation, that inherently alter the contractile properties of normally perfused myocardium (11,12). Once initiated, these maladaptive processes lead to a heart failure phenotype that is difficult to reverse by medical or surgical means.We have demonstrated that ventricular restraint early after MI reduces infarct expansion and limits long-term global LV remodeling in large-animal infarction models (10, 13-16). To circumvent the surgical placement of restraining devices early post-MI, our group and others have begun to explore the use of injectable materials to limit infarct expansion and normalize the regional stress distribution (17-26). Such an approach offers th...

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Photoproduction of a phi meson on protons was studied by means of linearly polarized photons at forward angles in the low-energy region from threshold to Egamma = 2.37 GeV. The differential cross sections at t = -|t|min do not increase smoothly as Egamma increases but show a local maximum at around 2.0 GeV. The angular distributions demonstrate that phi mesons are photoproduced predominantly by helicity-conserving processes, and the local maximum is not likely due to unnatural-parity processes.

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NASICON-type of solid-state electrolyte, Na3Zr2Si2PO12 (NZSP), is one of the potential solid-state electrolytes for all-solid-state Na battery and Na–air battery. However, in solid-state synthesis, high sintering temperature above 1200 °C and long duration are required, which led to loss of volatile materials and formation of impurities at the grain boundaries. This hampers the total ionic conductivity of NZSP to be in the range of 10–4 S cm–1. Herein, we have reduced both the sintering temperature and time of the NZSP electrolyte by sintering the NZSP powders with different amounts of Na2SiO3 additive, which provides the liquid phase for the sintering process. The addition of 5 wt % Na2SiO3 has shown the highest total ionic conductivity of 1.45 mS cm–1 at room temperature. A systematic study of the effect of Na2SiO3 on the microstructure and electrical properties of the NZSP electrolyte is conducted by the structural study with the help of morphological and chemical observations using X-ray diffraction (XRD), scanning electron microscopy, and using focused ion-beam-time of flight-secondary ion mass spectroscopy. The XRD results revealed that cations from Na2SiO3 diffused into the bulk change the stoichiometry of NZSP, leading to an enlarged bottleneck area and hence lowering activation energy in the bulk, which contributes to the increment of the bulk ion conductivity, as indicated by the electrochemical impedance spectroscopy result. In addition, higher density and better microstructure contribute to improved grain boundary conductivity. More importantly, this study has achieved a highly ionic conductive NZSP only by facile addition of Na2SiO3 into the NZSP powder prior to the sintering stage.