Experimental grain growth of quartz aggregates under wet conditions and its application to deformation in nature

Source at https://doi.org/10.5194/se-10-621-2019. Grain growth of quartz was investigated using two quartz samples (powder and novaculite) with water under pressure and temperature conditions of 1.0–2.5 GPa and 800–1100 ∘C. The compacted powder preserved a substantial porosity, which caused a slower grain growth than in the novaculite. We assumed a grain growth law of dn−dn0=k0frH2Oexp(−Q/RT)t with grain size d (µm) at time t (seconds), initial grain size d0 (µm), growth exponent n, a constant k0 (µmn MPa−r s−1), water fugacity fH2O (MPa) with the exponent r, activation energy Q (kJ mol−1), gas constant R, and temperature T in Kelvin. The parameters we obtained were n=2.5±0.4, k0=10−8.8±1.4, r=2.3±0.3, and Q=48±34 for the powder and n=2.9±0.4, k0=10−5.8±2.0, r=1.9±0.3, and Q=60±49 for the novaculite. The grain growth parameters obtained for the powder may be of limited use because of the high porosity of the powder with respect to crystalline rocks (novaculite), even if the differences between powder and novaculite vanish when grain sizes reach ∼70 µm. Extrapolation of the grain growth laws to natural conditions indicates that the contribution of grain growth to plastic deformation in the middle crust may be small. However, grain growth might become important for deformation in the lower crust when the strain rate is −12 s−1

Anti-Siglec-15 antibody suppresses bone resorption by inhibiting osteoclast multinucleation without attenuating bone formation

Anti-resorptive drugs are widely used for the treatment of osteoporosis, but excessive inhibition of osteoclastogenesis can suppress bone turnover and cause the deterioration of bone quality. Sialic acid-binding immunoglobulin-like lectin 15 (Siglec-15) is a transmembrane protein expressed on osteoclast precursor cells and mature osteoclasts. Siglec-15 regulates proteins containing immunoreceptor tyrosine-based activation motif (ITAM) domains, which then induce nuclear factor of activated T-cells 1 (NFATc1), a master transcription factor of osteoclast differentiation. Anti-Siglec-15 antibody modulates ITAM signaling in osteoclast precursors and inhibits the maturation of osteoclasts in vitro. However, in situ pharmacological effects, particularly during postmenopausal osteoporosis, remain unclear. Here, we demonstrated that anti-Siglec-15 antibody treatment protected against ovariectomy-induced bone loss by specifically inhibiting the generation of multinucleated osteoclasts in vivo. Moreover, treatment with anti-Siglec-15 antibody maintained bone formation to a greater extent than with risedronate, the first-line treatment for osteoporosis. Intravital imaging revealed that anti-Siglec-15 antibody treatment did not cause a reduction in osteoclast motility, whereas osteoclast motility declined following risedronate treatment. We evaluated osteoclast activity using a pH-sensing probe and found that the bone resorptive ability of osteoclasts was lower following anti-Siglec-15 antibody treatment compared to after risedronate treatment. Our findings suggest that anti-Siglec-15 treatment may have potential as an anti-resorptive therapy for osteoporosis, which substantially inhibits the activity of osteoclasts while maintaining physiological bone coupling.Tsukazaki H., Kikuta J., Ao T., et al. Anti-Siglec-15 antibody suppresses bone resorption by inhibiting osteoclast multinucleation without attenuating bone formation. Bone 152, 116095 (2021); https://doi.org/10.1016/j.bone.2021.116095

Dismantling and Reconstitution of Prasat Suor Prat, Angkor Thom, Cambodia

This paper presents geotechnical aspects of dismantling process of one of masonry towers named Prasat Suor Prat that had been constructed in the end of the 12th century during the Angkor Period in Cambodia. A series of 12 towers had been constructed from south to north along the east side of Royal Plaza in Angkor Thom. One of the towers, named as N1 Tower, was found badly displaced with inclination of about 5 degrees to the north-west and horizontal spreading at the foundation level. The Tower was dismantled before restoration work by JSA (Japanese Government Team for Safeguarding Angkor) to study possible mechanism that had caused inclination of the Tower and horizontal spreading of stair stones. Dismantling upper structures as well as foundation mound were performed by archaeological trench. The trench revealed the mechanism of deformation of the structure as well as foundation. Before the dismantling, the inclination was believed to be caused by tilting of the foundation mound caused by general sliding failure of the foundation towards adjacent pond. However, it was revealed that the mound was not tilted but kept horizontal under yielded state causing only horizontal spreading. It was found that the inclination was caused by slip down of the sidestep cut stones that had covered the side slopes of the mound

Field measurements of absolute gravity in East Antarctica

This paper reports the results of field-based absolute gravity measurements aimed at detecting gravity change and crustal displacement caused by glacial isostatic adjustment. The project was initiated within the framework of the 53rd Japanese Antarctic Research Expedition (JARE53). Absolute gravity measurements, together with GPS measurements, were planned at several outcrops along the Prince Olav Coast and Sôya Coast of East Antarctica, including at Syowa Station. Since the icebreaker Shirase (AGB 5003) was unable to moor alongside Syowa Station, operations were somewhat restricted during JARE53. However, despite this setback, we were able to complete measurements at two sites: Syowa Station and Langhovde. The absolute gravity value at the Syowa Station IAGBN (A) site, observed using an FG-5 absolute gravimeter (serial number 210; FG-5 #210), was 982 524 322.7±0.1 μGal, and the gravity change rate at the beginning of 2012 was –0.26 μGal∙a-1. An absolute gravity value of 982 535 584.2±0.7 μGal was obtained using a portable A-10 absolute gravimeter (serial number 017; A-10 #017) at the newly located site AGS01 in Langhovde

A Highly Advanced Gastric Cancer Maintaining a Clinical Complete Response after Chemoradiotherapy Comprising S-1 and Cisplatin

We report a patient with highly advanced gastric carcinoma who was treated successfully with chemoradiotherapy (CRT) comprising S-1 and cisplatin. The patient was a 71-year-old male who was diagnosed with advanced gastric carcinoma by esophagogastroduodenoscopy (EGD) by medical examination. EGD demonstrated type 3 advanced gastric carcinoma in the posterior wall of the upper gastric body. An abdominal computed tomography (CT) scan showed that the gastric wall was thickened due to gastric primary tumor, and large lymph nodes (LNs) including the lesser curvature LN, anterosuperior LN along the common hepatic artery and some para-aortic LNs were detected. The patient was diagnosed with stage IV advanced gastric carcinoma according to the Japanese classification of gastric carcinoma (cT4a, cN3, cM1 [para-aortic LN], cStage IV). Preoperative CRT was carried out in an attempt to downstage the disease. Remarkable reduction of the primary tumor and metastatic LNs was observed after initial CRT, and radiological examination determined that a partial response had been achieved. Adverse effects included grade 2 anorexia and grade 3 ALP elevation (919 U/ml). No grade 4 or more severe adverse event was observed. After CRT, although we recommended curative surgery, the patient refused surgical treatment and opted for conservative treatment. Thus, we continued S-1 oral administration for 1 year. Five months after beginning CRT, upper endoscopy showed that the tumor had maintained regression and scar formation, in which no cancer cells were detected by endoscopic biopsy. The patient is doing well and has maintained a clinical complete response for more than 42 months without curative surgery. CRT could be considered as an option for treatment of patients with locally advanced gastric carcinoma diagnosed as unresectable, or for those who refuse surgical treatment