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Osteoporosis deteriorates bone mass and biomechanical strength and is life-threatening to the elderly. In this study, we show that methyl 3,4-dihydroxybenzoate (MDHB), an antioxidant small-molecule compound extracted from natural plants, inhibits receptor activator of nuclear factor-κB (NF-κB) ligand (RANKL)-induced osteoclastogenesis in vitro. Furthermore, MDHB attenuates the activation of mitogen-activated protein kinase (MAPK) and NF-κB pathways by reducing the levels of reactive oxygen species (ROS), which leads to downregulated protein expression of c-Fos and nuclear factor of activated T cells c1 (NFATc1). We also confirm that MDHB upregulates the protein expression of nuclear factor-erythroid 2-related factor 2 (Nrf2), an important transcription factor involved in ROS regulation, by inhibiting the ubiquitination-mediated proteasomal degradation of Nrf2. Next, animal experiments show that MDHB has an effective therapeutic effect on lipopolysaccharide (LPS)- and ovariectomized (OVX)-induced bone loss in mice. Our study demonstrates that MDHB can upregulate Nrf2 and suppress excessive osteoclast activity in mice to treat osteoporosis.

To improve the low density and oxygen balance of the pure azido compounds, experimental research has been devoted to developing the modified azido compounds, such as azido nitramines, azido nitrate esters, and azido nitro compounds. Using the experimental methods to obtain a compound with suitable performance needs more resources than using theoretical tests, which makes the theoretical investigations meaningful. In this work, three azido compounds (I, II, and III) and their 27 modified derivatives were designed and studied using the density functional theory method. Results show that -NN[O.sub.2], -N[O.sub.2], and -ON[O.sub.2] all can improve the thermodynamic and energetic properties and the increment increases with the increasing number of substituent groups. The contribution to the thermodynamic properties is -ON[O.sub.2] > -N[O.sub.2] > -NN[O.sub.2] and that to the energetic properties is -NN[O.sub.2] > -ON[O.sub.2] > -N[O.sub.2]. The azido nitramines possess the best energetic properties and azido nitrate esters have the best thermodynamic properties. These substituents slightly decrease the thermal stability and the azido nitrate esters possess the lowest thermal stability. Systematical inspection of the substituent effect can direct experimental researchers to synthesize modified azido compounds purposefully and selectively. Key words: azido compound, modified azido compound, energetic property, stability, DFT. En vue de pallier l'inconvenient de la faible densite et d'ameliorer l'equilibre en oxygene des azotures purs, nous avons consacre des recherches experimentales a la mise au point d'azotures modifies, tels que les azotures de nitramines, les azotures de nitro-esters et les azotures nitres. L'emploi de methodes experimentales permettant d'obtenir un compose avec une efficacite acceptable requiert davantage de ressources que des tests theoriques, ce qui permet d'appuyer les recherches theoriques. Dans le cadre des presents travaux, nous avons elabore trois azotures (les composes I, II et III) et leurs 27 derives modifies, et nous les avons etudies au moyen de la methode basee sur la theorie de la fonctionnelle de la densite. Les resultats revelent que les substituants NN[O.sub.2], N[O.sub.2] et ON[O.sub.2] sont tous capables d'ameliorer les proprietes energetiques et thermodynamiques et que cette amelioration s'accroit avec le nombre de substituants. Les proprietes thermodynamiques sont influencees selon l'ordre ON[O.sub.2] > N[O.sub.2] > NN[O.sub.2] et les proprietes energetiques selon l'ordre NN[O.sub.2] > ON[O.sub.2] > N[O.sub.2]. Les azotures de nitramines possedent les meilleures proprietes energetiques, et les azotures de nitro-esters, les meilleures proprietes thermodynamiques. La presence de ces substituants entraine une legere diminution de la stabilite thermique, les azotures de nitro-esters possedant la plus faible stabilite thermique. L'examen systematique de l'effet des substituants peut orienter les recherches experimentales vers la synthese selective et rationnelle d'azotures modifies. [Traduit par la Redaction] Mots-cles : azoture, azoture modifie, propriete energetique, stabilite, DFT., Introduction Organic azides have received considerable attention in many fields and have wide applications. For example, they are widely utilized in synthetic chemistry. In particularly, organic azides are considered as [...]

In this paper, an SF‐3 double‐base propellant was treated by a supercritical carbon dioxide foaming process. Effects of the pressure of supercritical carbon dioxide on the morphology, energy level, and ingredients of the foamed SF‐3 double‐base propellant and the detonation performance of a perfusion explosive with the foamed SF‐3 double‐base propellant were studied. Results show that, with the increase of the pressure, the number of pores in the foamed SF‐3 double‐base propellant gradually increased, and some of the pores were connected to form a small amount of cracks. In the foaming process, the pressure had a small effect on the energy of foamed SF‐3, and the formation of dense pores increased the volume of the sample. The dense pores acted as "hotspots" during the detonation process of the perfusion explosive, allowing the explosive to have better detonation performance, as compared with the perfusion explosive with unfoamed SF‐3 which could not detonate effectively. When the pressure of supercritical CO2 was 8 MPa, the perfusion explosive with foamed SF‐3 had a shock wave energy of 1.06 kJ g−1 and a detonation velocity of 6521 m s−1. When the pressure was 11 MPa, the detonation velocity and shock wave energy of the perfusion explosive were 2.9 % and 6.6 % respectively higher than those under the pressure of 8 MPa. Therefore, with the increase of pressure, the detonation velocity and the shock wave energy of the perfusion explosive with foamed SF‐3 were increased, proving that increasing the pressure can effectively improve the detonation performance of perfusion explosives with foamed SF‐3. [ABSTRACT FROM AUTHOR]

In order to study the effects of different additives on the energy release of an SF‐3 double‐base propellant system comprising a boron‐containing hydrogen‐storage‐alloy (Mg(BHx)y), curves of heat generation versus the temperature and curves of adiabatic decomposition temperature versus the time, of this system with copper oxide (CuO) or nanometer copper oxide (nano‐CuO) as the additive were obtained by a scanning calorimeter (Scanning) and a fast ‐adiabatic accelerating rate calorimeter (Fast‐ARC), respectively. Kinetic parameters, such as the apparent activation energy, the pre‐exponential factor, and the reaction order were calculated. The effects of these two additives on the thermal decomposition of the SF‐3 double‐base propellant system containing Mg(BHx)y were investigated. The results show that CuO used in an amount within a certain range (1∼2.5 % based on the SF‐3 content) can promote the thermal decomposition reaction. When the amount of nano‐CuO added exceeds a certain value (about 2 % based on the SF‐3 content, the thermal decomposition reaction will be significantly slowed down, and the hindrance to the reaction will not be obviously changed after more nano‐CuO is added. [ABSTRACT FROM AUTHOR]

The cartilaginous endplate (CEP) is a thin layer of hyaline cartilage, and plays an important role in the diffusion of nutrients into the intervertebral discs. Its damage may seriously affect the disc degeneration, and result in low back pain (LBP). However, the structural features of damaged CEPs have not been well characterized, and this hinders our understanding of the etiology of disc degeneration and pain. To present the structural features of micro‐damaged CEPs in patients with disc degeneration and LBP that might even be regarded as an initial factor for disc degeneration, we performed a histological study of micro‐damaged CEPs harvested from human lumbar intervertebral discs and analyzed its clinical implications. Human lumbar CEPs were excised from 35 patients (mean age 60.91 years) who had disc degeneration and LBP. Control tissue was obtained from 15 patients (mean age 54.67 years) with lumbar vertebral burst fractures. LBP and disability were assessed clinically, and all patients underwent anterior vertebral body fusion surgery. CEPs together with some adjacent nucleus pulposus (NP) were sectioned at 4 µm, and stained using H&E, Safranin O/Fast Green, and Alcian Blue. Immunostaining and PCR were used to identify various markers of degeneration, innervation, and inflammation. Histology demonstrated physical micro‐damage in 14/35 CEPs from the disc degeneration group. Six major types of damage could be distinguished: fissure, traumatic nodes, vascular mimicry, incorporation of NP tissue within the CEP, incorporation of bone within the CEP, and incorporation of NP and bone within the CEP. Pain and disability scores (ODI: p = 0.0190; JOA: p = 0.0205; JOABPEQ: p = 0.0034) were significantly higher in those with micro‐damaged CEPs (N = 14) than in those with non‐damaged CEPs (N = 21). CEP damage was significantly associated with elevated MMP3 (p = 0.043), MMP13 (p = 0.0191), ADAMTS5 (p = 0.0253), TNF‐α (p = 0.0011), and Substance P (p = 0.0028), and with reduced Sox9 (p = 0.0212), aggrecan (p = 0.0127), and type II collagen (p = 0.0139). In conclusion, we presented a new classification of human lumbar micro‐damaged CEPs. Furthermore, we verify disc degeneration, innervation, and discogenic pain in micro‐damaged CEPs. [ABSTRACT FROM AUTHOR]

The supercritical CO2 foaming process is a preferable way to treat deserted SF‐3 propellants and solves problems of environmental pollution and waste of resources related to conventional treatment methods, and this process is an environmentally friendly method. In this paper, the effect of process conditions, including the immersion time of deserted SF‐3 propellants in the supercritical CO2 fluid, on the appearance of SF‐3 propellants and detonation performance of the perfusion explosive made from SF‐3 propellants are mainly studied. The results show that the diameter of foamed SF‐3 propellants increases with the immersion time when the immersion time is less than 60 min. When the immersion time is 60 min, the performance of the perfusion explosive made from foamed SF‐3 propellants is the best. The highest detonation velocity is 6683 m s−1, and the corresponding shock wave energy is 1.02 kJ g−1. When the immersion time is more than 60 min, the detonation velocity and the shock wave energy of the perfusion explosive made from foamed SF‐3 propellants decreases with the increase of the immersion time. [ABSTRACT FROM AUTHOR]

Abstract: Thermal decomposition properties and hazards of nitrate explosives containing Mg(BHx)y were investigated by thermogravimetry‐differential scanning calorimetry (TG‐DSC), accelerating rate calorimeter (ARC) and characteristic drop height impact sensitivity tests. Results show that the addition of Mg(BHx)y to nitrate explosives led to increase in the volatilization temperature of nitroglycerine in the nitrate explosive. It was not the thermolysis product of Mg(BHx)y, but Mg(BHx)y itself acted on the nitrate explosive in the TG‐DSC tests. Kinetic parameters and thermal hazard assessment parameters were calculated based on ARC data. Results show that a mixture of the nitrate explosive with Mg(BHx)y had higher apparent activation energy and lower thermal hazard. Experiments of characteristic drop height showed that Mg(BHx)y reduced the impact sensitivity of nitrate explosives. [ABSTRACT FROM AUTHOR]

This paper used a supercritical CO 2 batch foaming process to treat a waste SP double-base propellant, which is a type of double-base propellants containing 58.6% nitrocellulose, 40.0% nitroglycerin, 0.8% centralite, and 0.5% vaseline, to solve a problem of poor stability of industrial explosives directly prepared by the propellant. Experiments show that this process can produce dense pores inside the SP double-base propellant. With the increase of the pressure of supercritical CO 2 , the number of pores inside the foamed SP double-base propellant increased, and these pores served as hotspots in the detonation reaction. An increased number of hotspots improved the detonation stability of the perfusion explosive. During the explosion, the energy of the perfusion explosive with the foamed SP double-base propellant was released more completely, so the shock wave energy and bubble energy of the explosive gradually increased with the increase of pressure. Therefore, the supercritical CO 2 foaming process can promote the treatment technology of waste double-base propellants and can optimize the detonation performance of perfusion explosives by increasing the pressure of supercritical CO 2 ., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

Objective: To explore the expression of lubricin in the lumbar endplate and its association with Modic changes (MCs)., Methods: Human endplate specimens harvested from patients undergoing surgery for thoracolumbar spine fractures ​or lumbar interbody fusion were divided into two groups: MCs group and normal group. Lubricin expression was examined by immunohistochemistry, and differences between the groups were analysed using quantitative polymerase chain reaction (qPCR). Lubricin expression and differences between endplates with MCs and normal endplates were confirmed using a rabbit model. In a final experiment, rabbit endplate chondrocytes were cocultured with Propionibacteria acnes ( P. acnes ) supernatant, and the expression of lubricin and endplate degeneration related genes were evaluated. In addition, the expression of matrix metalloproteinase 1(MMP-1), A disintegrin-like and metalloproteinase with thrombospondin type 5 motif (ADAMTS5) and inflammatory factors (Interleukin- 1β (IL-1β) and Interleukin-6 (IL-6)) were evaluated after lubricin overexpression., Results: Lubricin was found in human lumbar endplates and its expression was lower in the MCs group compared to the normal group. In the rabbit model, lubricin was also found in the endplate. In rabbits injected with P. acnes (the MCs group), lubricin expression of endplate decreased compared to the normal group. In the culture of rabbit endplate chondrocytes with P. acnes supernatant, the expression of lubricin, aggrecan, sox9 and collagen type-II decreased significantly, while that of MMP-1 and ADAMTS5 increased significantly. Moreover, lubricin overexpression could downregulate the expression of MMP-1, ADAMTS5 and inflammatory factors (IL-1β and IL-6) compared to negative control., Conclusion: Lubricin is present in the lumbar endplate where it may have an anti-inflammatory role. P. acnes infection inhibits lubricin expression by cartilage endplate cells and this may facilitate the progression of MCs and endplate degeneration., The Translational Potential of This Article: Lubricin may have an anti-inflammatory role. P. acnes infection inhibits lubricin expression by cartilage endplate cells and this may facilitate the progression of MCs and endplate degeneration., (© 2019 The Authors.)