El Niño-Southern Oscillation forcing on carbon and water cycling in a Bornean tropical rainforest.

Carbon dioxide and water vapor exchanges between tropical forest canopies and the atmosphere through photosynthesis, respiration, and evapotranspiration (ET) influence carbon and water cycling at the regional and global scales. Their inter- and intra-annual variations are sensitive to seasonal rhythms and longer-timescale tropical climatic events. In the present study, we assessed the El Niño-Southern Oscillation (ENSO) influence on ET and on the net ecosystem exchange (NEE), using eddy-covariance flux observations in a Bornean rainforest over a 10-y period (2010-2019) that included several El Niño and La Niña events. From flux model inversions, we inferred ecophysiological properties, notably the canopy stomatal conductance and "big-leaf" maximum carboxylation rate (Vcmax25_BL). Mean ET values were similar between ENSO phases (El Niño, La Niña, and neutral conditions). Conversely, the mean net ecosystem productivity was highest during La Niña events and lowest during El Niño events. Combining Shapley additive explanation calculations for nine controlling factors with a machine-learning algorithm, we determined that the primary factors for ET and NEE in the La Niña and neutral phases were incoming shortwave solar radiation and Vcmax25_BL, respectively, but that canopy stomatal conductance was the most significant factor for both ET and NEE in the El Niño phase. A combined stomatal-photosynthesis model approach further indicated that Vcmax25_BL differences between ENSO phases were the most significant controlling factor for canopy photosynthesis, emphasizing the strong need to account for ENSO-induced ecophysiological factor variations in model projections of the long-term carbon balance in Southeast Asian tropical rainforests.

Implant fracture under dynamic fatigue loading: influence of embedded angle and depth of implant.

The purpose of this study was to investigate the relationship between implant fracture under cyclic-fatigue loading at different embedding angles, embedding depths, and loading forces. Twenty-four cylinder-type implants 3.3 mm in diameter and 10 mm in length were used. Test specimens were 30 mm(3) resin blocks with one surfaces inclined at angles of either 5°, 10°, 15° and 20° and embedded vertically with implants at depths of either 5 or 10 mm to the these surfaces. A straight abutment was connected to the implant and cut to 5 mm in length, and a hemispherical crown 5 mm in diameter and 7 mm in length was cast with a 12 % gold-silver-palladium alloy and cemented onto the abutment. Each specimen was mounted onto a fatigue loading device to apply repeated vertical loads of 294, 392, and 490 N to the coronal edge of the crown 60 times per min until reaching 100,000 cycles. For each respective specimen, we recorded the combined conditions of embedding and loading forces and the number of loading cycles until fracture, and then observed the fracture sites microscopically. The number of loading cycles until implant fracture tended to decrease in proportion to increased loading forces and embedded angles, and decreased embedded depths. Implant fracture was observed at angles of inclination over 10°. For specimens with an implant embedded at a depth of 5 mm, almost all fractures occurred at the center of the implant body; however, for those embedded at a depth of 10 mm, fractures occurred at the interface between the implant body and the abutment. These results demonstrate that implant fracture is associated with the loading axis, the amount of loading, and the embedded depth of the implant.

The structural phase transition in SrV(6)O(11).

Single-crystal X-ray diffraction and specific heat studies establish that strontium hexavanadium undecaoxide, SrV(6)O(11), undergoes a P6(3)/mmc to inversion twinned P6(3)mc structural transition as the temperature is lowered through 322 K. The P6(3)/mmc and P6(3)mc structures have been determined at 353 K and at room temperature, respectively. For the room-temperature structure, seven of the ten unique atoms lie on special positions, and for the 353 K structure all of the seven unique atoms sit on special positions. The P6(3)/mmc to P6(3)mc structural phase transition, accompanied by a magnetic transition, is a common characteristic of AV(6)O(11) compounds, independent of the identity of the A cations.

The change in retentive force of magnetic attachment by abrasion.

Magnets are frequently applied to removable dentures as retentive attachments. A magnet-retained removable overdenture might be slightly shifted from side to side by eccentric movement in the mouth, and the surface of magnetic attachment may be worn as a result. However, the relationship between the retentive force of magnetic attachment and its surface abrasion has not been reported. The purpose of this research is to investigate this relationship. Ten Mgfit DX 400 magnetic attachments for natural tooth roots were used for this experiment. The magnetic attachments were embedded in autopolymerizing acrylic resin, and ten pairs of specimens were fabricated. A 5-mm repeated gliding motion was applied on each pair of specimens until 30 000, 50 000, or 90 000 cycles had been achieved. The abrasion machine was under 5 kg loading, and the slide speed was 60 times/min. The retentive force of magnetic attachment was measured with a tension gauge at (1) before gliding; (2) after 30 000 gliding cycles; (3)after 50 000 gliding cycles; or (4) after 90 000 gliding cycles. The average change of retentive force of ten magnetic attachments after 30 000, 50 000, and 90 000 gliding cycles was 0.016 N, 0.003 N, and -0.008 N, respectively. The change was statistically analyzed using a paired-sample t test, which showed that the number of gliding cycles did not affect the retentive force of magnetic attachment significantly. The surface of magnetic attachment after gliding was observed by a microscope, and the abrasion of this attachment surface is clearly seen.

[Effect of beta-TCP containing the bone-growth promoting compound, TAK-778, on the vertex bone of rat--change of volmetric bone formation corresponding to the containing volume of TAK-778].

PURPOSE: This study was conducted to histomorphologically determine the quantity of bone formation induced by TAK-778, a 3-benzothiepin derivative, (Takeda Pharmaceutical Co.Ltd.), in various amounts, using b-tricalcium phosphate granules (beta-TCP; OLYMPUS Corp.) as a carrier for the osteogenetic agent. METHODS: Ten-week-old female SD rats were used. An incision was made over the parietal region of the head. The cranial periosteum was ablated and a titanium tube was fixed with an adhesive resin cement to the central part of the head, through which a mixture of TAK-778 and beta-TCP was implanted under various conditions. Tissue specimens were prepared at 4, 8, and 16 weeks after the implantation for histomorphological examination, and the proportion of new bone formation was compared at fixed time points using the NIH imaging software. The amount of new bone formation was examined every week after the implantation of TAK-778 at various doses, and the mean values were compared using Fisher's PSLD test (P< 0.05). RESULTS: The histomorphological observations revealed new bone formation in all the groups, irrespective of the amount and the duration of implantation of TAK-778. A comparative study revealed that the amount of new bone formation was the largest at 16 weeks following the implantation of a mixture of beta-TCP and 100 mg of TAK-778. CONCLUSIONS: 1. The present study confirmed the acceleration of new bone formation soon after TAK-778 implantation. 2. The results suggested that the action of TAK-778 could be maintained over time if the agent was used in combination with beta-TCP. 3. The time-course of bone formation differed depending on the proportion of TAK-778 and beta-TCP in the mixture used. 4. TAK-778 at the dose of 10 mg or 50 mg was more effective than that at the dose of 100 mg for the early formation of new bone. These results indicate that TAK-778 accelerates the formation of new bone and that beta-TCP is a useful carrier for TAK-778.

[Assessment of beta-tricalcium phosphate as a carrier for bone formation promoting agent, TAK-778-SR].

PURPOSE: The aim of this study was to evaluate the combination of TAK-778-SR which was sustained-release microcapsules of a bone formation stimulant, TAK-778, and its carrier beta-tricalcium phosphate (beta-TCP) blocks (pore rates 60%, 75% respectively). The difference of their abilities in bone-formation was evaluated histomorphologically by varying the following conditions: with or without TAK-778, pore ratio of carrier and embedding period. METHODS: Nine-week-old female SD rats were used. After removing the parietal bone from the head with a trephine bar, the defects were refilled by beta-TCP blocks immersed with or without TAK-778 under the following conditions: saline solution, release microcapsules only, and release microcapsules with TAK-778 (TAK-778-SR). These rats were sacrificed after 5 and 10 weeks and their histological specimens were prepared. Morphological change was observed and the formation rates of each new bone were compared using an NIH imaging program. RESULTS: A significant amount of new bone was morphologically observed in all beta-TCP samples that were treated with TAK-778-SR. A high rate of new bone formation was confirmed in the 10-week samples (pore rate 75%, with TAK-778-SR) with the NIH imaging. CONCLUSIONS: 1. beta-TCP and release microcapsules did not disturb the recovery process. 2. Five- and 10-week samples (pore rate 60%) were absorbed marginally. 3. Absorption was observed in the 5-week samples (pore rate 75%), and it was accelerated further at 10 weeks. 4. An accelerating bone-formation effect of TAK-778-SR was confirmed and beta-TCP block was proved to be highly useful as a carriage material.

[Effect of prism length on the notchless triangular prism fracture toughness test].

PURPOSE: The purpose of this study was to clarify the effect of holding condition with different prism length on the Notchless Triangular Prism (NTP) fracture toughness test and to define the prism length as a measuring condition. METHODS: Two kinds of NTP prism (ceramic and composite resin) were fabricated by CAD/CAM and each prism was adjusted to one of three lengths (8.0 mm, 12.0 mm, 16.0 mm). NTP was conducted for prism specimens made under six different conditions. The displacement of prism specimen holder gap (Delta d) and maximum fracture load (Pmax) were recorded and then a fractogram of each prism was inspected by SEM. RESULTS: Inclined stable fracture propagation was observed on the fractogram of the 8.0-mm prism. Both Delta d and Pmax of the 8.0-mm prism were significantly higher than those of the other lengths. CONCLUSIONS: A prism length of at least 12.0 mm is needed for the NTP because the 8.0-mm prism did not have a sufficient holding condition. The fracture toughness of the ceramic (3.68+/-0.09 MPa.m(1/2)) was significantly higher than that of the composite resin (2.38+/-0.20 MPa.m(1/2)).

Acceleration effect of human recombinant bone morphogenetic protein-2 on differentiation of human pulp cells into odontoblasts.

Predictable pulp capping procedures remain problematic, possibly because of the lack of appropriate stimulating factors for dentin formation. The present study examines the ability of one such stimulating factor, bone morphogenetic protein-2, to accelerate the differentiation of human dental pulp cells into odontoblasts. The number and morphology of cells between groups treated with 0 and 100 ng/ml of human recombinant bone morphogenetic protein-2 (rhBMP-2) did not significantly differ. However, ALPase activity (a marker for biomineralization) in the group stimulated with rhBMP-2 was more than double that of the control group. We then measured the expression of mRNA encoding dentin sialophosphoprotein (DSPP) as a marker of odontoblasts in rhBMP-2-stimulated human pulp cells using a quantitative polymerase chain reaction. The expression of DSPP mRNA in cells stimulated for 24 h by 1000 ng/ml of rhBMP-2 was approximately 20-fold and 5-fold higher than that by stimulated by 10 and 100 ng/ml, respectively. These findings show that rhBMP-2 promoted the differentiation of human dental pulp cells into odontoblasts but did not affect cell proliferation, suggesting that rhBMP-2 may have therapeutic utility in vital pulp therapy.

Finite element analysis of the influence of implant inclination, loading position, and load direction on stress distribution.

The selection of the appropriate alignment of an implant and the position of implantation are vital for its longterm success. Excessive load is generated around inclined implants, causing microcracks in the bone, which result in implant loosening and eventual failure. This study was designed to analyze the stress distribution caused by varying the degree of inclination of an implant body and varying the loading position and direction, using the finite-element method of stress analysis. Buccal and lingual two-dimensional simulation models of a cylinder implant, embedded in the first molar edentulous cross-section of the mandible, were prepared, and the stress distribution and maximum principal stresses were recorded. Regardless of the point and direction of loading, compressive stresses were relatively greater when the implant was inclined. This tendency became more pronounced when a 45 degrees loading direction and eccentric loading were tested. For the inclined model, with a 45 degrees loading direction, the compressive stress was observed on the cortical bone adjacent to the direction of inclination, while tensile stress was observed on the opposite side.

Retrieval and replacement of a malpositioned dental implant: a clinical report.

This clinical report describes the retrieval of a malpositioned mandibular implant with a severe lingual inclination. A replacement implant was inserted with an emphasis on its relationship with the maxillary antagonist, resulting in a buccal inclination of approximately 10 degrees. The treatment review highlights the importance of thorough communication among all members of the dental implant team.