Horizontal Shrinkage Research Articles

Dynamic crushing responses of enhanced auxetic re-entrant honeycomb based on additive manufacturing

Recently, auxetic re-entrant honeycombs have gained a significant deal of attention due to their superior mechanical qualities. In this work, a star-enhanced auxetic re-entrant honeycomb (S-ARH) is proposed by combining a star-shaped re-entrant honeycomb (SRH) with an auxetic re-entrant honeycomb (ARH). Experimentally validated finite element models are used to investigate the deformation modes, horizontal shrinkage strains, and stress-response relationships of the S-ARH at various crushing velocities. The deformation modes of S-ARH are essentially identical to the ARH. The integration of star-shaped structures causes S-ARH to form a compact zone earlier but with a lower horizontal shrinkage capacity. Additionally, the plateau crushing stress σp and specific energy absorption of S-ARH are also calculated to illustrate the ability to absorb energy and the resistance to impact. A methodical equation for the dynamic compressive strength is derived based on the collapse mechanism of the S-ARH, and the finite element confirms the applicability of the derived equation. Finally, an evaluation is conducted to examine how various structural parameters influence the dynamic performance of S-ARH.

Case study on long-term deformation monitoring and numerical simulation of layered rock slopes on both sides of Wudongde dam reservoir area

Layered rock slope exists widely. Because of its special slope structure, it is prone to bending deformation and toppling failure, which is a serious threat to engineering construction and safety operation. At present, the research of layered rock slope still has great innovation potential. During the construction of Wudongde Hydropower Station on Jinsha River, safety and stability problems such as slope geological structure development, face rock unloading and relaxation, and even slip and large deformation were encountered. Through field exploration, it is found that the rock and soil stratification of the slope on both sides of Wudongde Hydropower Station is highly obvious. At present, there is a lack of research on-site long-term displacement monitoring of layered rock high-steep slope, especially for layered slope in complex hydrogeology and construction environment. In order to strengthen the research on the deformation and stability of layered rock slope, this paper analyzes the measured displacement data of Wudongde hydropower station slope, and establishes three-dimensional geological finite element model with the help of numerical simulation software. The stability of the slope is calculated by combining the finite difference method and the strength reduction method. Finally, the evolution mechanism of the deformation of the layered rock slope is explained according to the geological structure characteristics. The main conclusions of this paper are as follows: the layered slope in the dam reservoir area is prone to deformation under the combined action of long-term construction disturbance and fissure water seepage, and the construction disturbance has a strong influence on the artificial excavation area below 1070 m, and the maximum rock mass deformation and surface displacement in the artificial excavation area of the slope reach 92.2 mm and 312.5 mm, respectively. However, the influence of construction disturbance on the natural mountain above 1070 m is limited, the valley deformation of the natural mountain on the left bank of the reservoir area is higher than that on the right bank, and the cumulative deformation is still less than 20 mm. The influence of seepage on the displacement of the area with higher elevation at the top of the slope is more obvious, and the influence of excavation and other disturbances on the displacement of the artificial excavation area with lower elevation is more obvious. The deformation of the river valley in the water cushion pond behind the dam increases slowly, and the change trend of the field deformation data is mostly consistent with that of the numerical calculation. The horizontal shrinkage of the mountains on both sides shows a contraction trend on the whole, and the maximum horizontal shrinkage calculated by numerical simulation is close to 20 mm, which is located at the elevation of 990 m.

Hygromechanical study of a 16th century painted wooden panel: In-situ experiments to quantify the mechanical effect of the frame and the cradle

In order to prevent damage to painted wooden panels from the cultural heritage sector, curators and conservators must provide the hygroscopic and thermal conditions necessary for their conservation. Furthermore, the design of physical reinforcements such as frames or cradles has to be considered. In this paper, experiments were designed to determine the kinematic response of a painting to hygrometric variations both before and after remedial conservation treatments were undertaken. This study was carried out in the Fabre Museum, Montpellier on the panel painting “La Sainte Trinité couronnant la Vierge” (« The Coronation of the Virgin by the Holy Trinity »), which was placed in a climate-controlled showcase in a museum exhibition space. A glass panel on either side allowed visitors to see both sides of the panel during the experiment. At the same time, two stereoscopic devices allowed us to follow the relief, the shape deformation and surface strain of the panel on its front and back sides. First, the mechanical effect of the frame and cradle was studied. The majority of the deformation was found to be due to the cradle; initially the panel had a complex warp (-5 to 10 mm), decreasing to (-1 to +2 mm) when the cradle was removed. The continuous monitoring (two images per hour) was carrried out to assess the behaviour of the panel during imposed relative humidity (RH) variations of about 13 % RH (between 65 % RH for the maximum and 52 % RH for the minimum) for both the absorption and desorption phases. The global mechanical effect on the curvature was very clear with an opposite direction of deflection between absorption and desorption phases. A comparison of the behaviour of the panel with and without the cradle showed that the change in curvature was about twice as great (4 mm) without the cradle, and its direction moved from an initial slight negative curvature state to a positive one. In terms of strain on both the surfaces, we observed a horizontal shrinkage of about -0.1 % during the desorption phase and a swelling of about +0.1 % during the absorption phase for both the front and back sides of the panel. A further local study allowed us to assess the mechanical phenomenon for each board with the local determination of cupping angles and surface strains. This local study highlighted the change in behaviour of the panel without the cradle. On both sides, the local surface strains were decomposed into the mean strain and the deviation from the mean strain. The study highlighted the fact that the intensity of the mean strain (local swelling or shrinkage due to the hygroscopic changes) was the same for each configuration and was about 0.1 %. Nevertheless, in the case of the panel without the cradle, the imposed variation of relative humidity was smaller (8 % RH instead of 13 % RH), so proportionally the mean strain is higher compared to the case with a cradle. This study over five years has been success in terms of innovative development and multidisciplinary research.

Environmental and human facets of the waterweed proliferation in a Vast Tropical Ramsar Wetland-Vembanad Lake System.

The Vembanad Lake and its associated low-lying areas and network of canals (hereafter VBL) form the major part of India's second-largest Ramsar wetland (1512 km2) located in Kerala State alongIndia's southwest coast. The extensive VBL has a large fishery, inland waterways, and popular tourist attractions that support the livelihoods of thousands of people. Over the last several decades, the proliferation of water weeds in the VBL has alarmingly increased, causing many adverse ecological and socioeconomic effects. This study based on a review and synthesis of long-term data introduced the environmental and human dimensions of water weed proliferation in the VBL. Eichhornia (= Pontederia) crassipes, Monochoria vaginalis, Salvinia molesta, Limnocharis flava, Pistia stratiotes, and Hydrilla verticillata are the most troublesome water weeds in the VBL, with the first three being the most widespread. They were mostly imported to India long ago before becoming a part of the VBL.These weeds harmed water quality, waterways, agriculture, fisheries, disease vector management, as well as the vertical and horizontal shrinkage of the VBL through increased siltation and faster ecological succession. The inherently fragile VBL was harmed by extensive and long-term reclamation, the construction of saltwater barrages, and many landfill roads that crisscross water bodies serving as coastal dams, creating water stagnation by blocking natural flushing/ventilation by periodic tides from the adjacent southeastern Arabian Sea. These ecological imbalances were exacerbated by excessive fertiliser use in agricultural areas, as well as the addition of nutrient-rich domestic and municipal sewage, which provided an adequate supply of nutrients and a favourable habitat for the expansion of water weeds. Furthermore, because of recurrent floods and a changing ecology in the VBL, the water weed proliferation has become a more significant problem, with the potential to disrupt their current distribution pattern and spread in the future.

Muscle-Like Supramolecular Polymers with Dual Motion Patterns.

Benefiting from the features like polymeric linear structures, stimuli-responsiveness and dynamic adaptiveness, supramolecular polymers (SPs) are favored as exploiting muscle-like materials, allowing for imitating the muscle functions. However, a substantial part of these materials barely owned an unitary motion orientation while it was obviously known that muscle movements involved distinct orientations. Herein, M1 holding the structure of 44-membered macrocycle with two aldehyde groups was designed, meanwhile, M2 comprising of secondary ammonium ions, 3,5-di-tert-butylphenyl groups as well as the alkyl chains was fabricated, for which it could be assembled with M1 to generate SPs based on host-guest interactions from a large macrocycle and two secondary ammonium ions. SPs underwent vertical compression upon the addition of N2 H4 owing to the forming dynamic covalent bonds, notably, mechanically interlocked structures were also generated. Afterwards, the vertically compressed SPs experienced horizontal shrinkage when tetrabutylammonium chloride was contributed due to the destruction of host-guest interactions.

Experimental characterization of desiccation cracking mechanisms in clayey soils

Desiccation cracking in clayey soils is a complex phenomenon investigated by researchers over many decades. Understanding and mitigating this issue will have a significant influence on the performance of raw earth construction materials and geotechnical engineering. In the current study, the digital image correlation technique was used to provide a thorough insight about the shrinkage anisotropy and the cracking mechanisms during drying. A series of free shrinkage tests were performed on an initially saturated slurries in order to assess the effects of the intrinsic characteristics of the material, the surface tension, the sample thickness and the geometric boundary conditions on the crack initiation and propagation in clays. The results show that increasing sample thickness prevents cracks formation in a non-swelling clay and delays it in a swelling clay. A vertical uplift was observed in the swelling clay due to a concave bending of the material during the desiccation shrinkage. An important anisotropy in the vertical shrinkage was observed compared to the horizontal shrinkage. The geometric boundary conditions indirectly influence the internal drying stress that becomes anisotropic. The intrinsic characteristics have a greater effect on the shrinkage behavior of the material than the hygrothermal and geometric boundary conditions.

Dimensional Alterations Following Immediate Implant Placement Using the Socket-Shield Technique in the Anterior Maxilla: A Case Series

Tissue volume loss after tooth extraction is an esthetic challenge. The socket-shield technique (SST) has been used to compensate it with promising results but limited evidence. This prospective study aims to present the dimensional changes after SST. Ten consecutive patients with an anterior hopeless tooth to be extracted and an immediate implant placed using the SST were prospectively enrolled. An impression and a CBCT scan were taken prior to surgery and 6 months later. Models were scanned, and DICOM and STL (standard tessellation language) files were superimposed and analyzed by software to measure the dimensional differences. Five patients could be evaluated for bone alterations and 9 for soft tissue alterations. The mean horizontal shrinkage of the buccal bone plate at 1 mm from the most coronal part was -0.22 ± 0.13 mm in the CBCT analysis. The mean volume loss in the region of interest was -2.94 ± 2.45 mm3, with a mean change in soft tissue contours of -0.49 ± 0.41 mm between pre- and postoperative analysis. SST limited the buccal contour loss after tooth extraction and may be considered a potential option to prevent volume loss in immediate implant placement. Further standardization in the digital measurement method is still needed.

Experimental Investigation on the Impact of Drying–Wetting Cycles on the Shrink–Swell Behavior of Clay Loam in Farmland

Soil shrink–swell behavior is a common phenomenon in farmland, which usually alters the process of water and solute migration in soil. In this paper, we report on a phenomenological investigation aimed at exploring the impact of drying–wetting cycles on the shrink–swell behavior of soil in farmland. Samples were prepared using clay loam collected from farmland and subjected to four drying–wetting cycles. The vertical deformation of soil was measured by a vernier caliper, and the horizontal deformation was captured by a digital camera and then calculated via an image processing technique. The results showed that the height, equivalent diameter, volume and shrinkage-swelling potential of the soil decreased with the repeated cycles. Irreversible deformation (shrinkage accumulation) was observed during cycles, suggesting that soil cracks might form owing to previous drying rather than current drying. The vertical shrinkage process consisted of two stages: a declining stage and a residual stage, while the horizontal shrinkage process had one more stage, a constant stage at the initial time of drying. The VG-Peng model fit the soil shrinkage curves very well, and all shrinkage curves had four complete shrinkage zones. Drying–wetting cycles had a substantial impact on the soil shrinkage curves, causing significant changes in the distribution of void ratio and moisture ratio in the four zones. However, the impact weakened as the number of cycles increased because the soil structure became more stable. Vertical shrinkage dominated soil deformation at the early stage of drying owing to the effect of gravity, while nearly isotropic shrinkage occurred after entering residual shrinkage. Our study revealed the irreversible deformation and deformation anisotropy of clay loam collected from farmland during drying–wetting cycles and analyzed the shrink–swell behavior during cycles from both macroscopic and microscopic points of view. The results are expected to improve the understanding of the shrink–swell behavior of clay loam and the development of soil desiccation cracks, which will be benefit research on water and solute migration in farmland.

Effect of a novel shrinkage-reducing polycarboxylate superplasticiser on plastic shrinkage cracking of mortars

Plastic shrinkage cracking propagating at early ages inevitably impairs the performance of concrete structures. To mitigate this, using a recently developed shrinkage-reducing polycarboxylate superplasticiser (SR-PCA) with outstanding shrinkage-reducing and water-reducing effectiveness can be a promising approach. The present work aims to investigate the effect of SR-PCA on plastic shrinkage cracking and to clarify the underlying mechanisms. For comparison, a traditional polyether type shrinkage reducing admixture (SRA) and a polycarboxylate superplasticiser (PCA) were also used. Based on the investigations on horizontal shrinkage, settlement, bleeding, evaporation mass loss, cement hydration, surface tension of pore fluid and capillary pressure, the underlying working mechanisms of SR-PCA were identified. The results indicate that SR-PCA is able to reduce the crack area, maximum crack width and average crack width by up to 55, 48 and 50%, respectively. Furthermore, prolonging the bleeding duration and initial time of capillary pressure build-up caused by retarding the cement hydration, lowering the evaporation mass loss, and a lower development rate of capillary stresses and capillary pressure peak value induced by decreasing the surface tension of pore fluid are responsible for preventing the plastic shrinkage cracking of mortars containing SR-PCA.

On the dendrite deformation and evolution mechanism of Ni-based superalloy during directional solidification

The dendritic growth in a novel casting with complex solidification path during directional solidification was investigated by experiment and simulation. The different dendrite deformations were found in the side strip and the corner, and the misorientation was measured by electron backscattered diffraction. The dendrite deformation in the local strip above each platform causes the cumulative deviation of dendrite direction in the whole strip, and this deformation is caused by the differential thermal shrinkage between upper and lower cross-sections. In addition, the dendrite with incomplete trunk concentrately deformed in the corner, and the deviation direction is consistent with its branches toward the platform, indicating that the deformation occurs before branching and thereby thermal concentrated stress is excluded. The simulation results confirm the occurrence of horizontal shrinkage stress in the mushy zone of the platform when the dendrites in the sidebar leave the platform, and also determine that the dendrite branches occur before the effect of the thermal concentration stress in the corner.

Design, thermal shock resistance of dense BaO‐Al2O3‐SiO2 glass/Si3N4‐barium feldspar coating for porous Si3N4 ceramic

AbstractSilicon nitride‐monoclinic barium feldspar (Si3N4‐m‐BAS) composite possesses great dielectric properties, low density, and low thermal expansion coefficient (CTE). Preparing dense Si3N4‐m‐BAS coating on porous Si3N4 ceramic is an effective strategy to improve its water resistance and ensure its dielectric performances. However, this promising coating has not been reported yet, because the synthesis of m‐BAS is difficult, and the densification of Si3N4‐BAS composite requires very high temperature. Here, the BaO‐Al2O3‐SiO2 glass/Si3N4‐BAS coating was first fabricated by a manual spray method and pressureless sintering at 1450°C. Combining the influence of Si4+ on the crystal phase composition of BAS and the volume expansion effect of silicon in N2, an effective coating structure design scheme was proposed. By changing the content of silicon powder, the CTE and horizontal shrinkage of the coating during sintering were controlled. Besides, the prepared coatings exhibited low water absorption and high bonding strength. During the thermal shock tests, SiO2 produced by the oxidation of Si3N4 healed the cracks in the coating, thus delaying the degradation of the properties. The coating prepared in this work is expected to be applied to radome in extreme service environments.

Clinical, radiographical and histological evaluation of alveolar ridge preservation with an autogenous tooth derived particulate graft in EDS class 3\u20134 defects

BackgroundThe shrinkage of alveolar bone dimensions after tooth extraction is a well-known issue. This clinical phenomenon poses a challenge for clinicians aiming at implant-prosthetic treatment. BonMaker® ATB is a novel autogenous bone grafting material, produced by the mechanical and chemical processing of natural teeth. This pilot case report aims at providing a clinical, radiographical, and histological evaluation of the safety and efficacy of Bonmaker ATB powder in the treatment of EDS class 3–4 postextraction sockets with alveolar ridge preservation.MethodsA total of 9 teeth were extracted from 5 patients. The extracted teeth were prepared immediately with the Bonmaker® device. The extraction sockets were filled up with ATB powder. Six months after extraction, standardized intraoral x-rays and CBCT scans were performed. Re-entry was performed under local anaesthesia. Core biopsies were harvested for histological analysis and implants were placed.ResultsHorizontal alveolar dimension loss occurred, even though ARP was performed, but the horizontal shrinkage was moderate. Vertical dimensions did not show loss of volume, but increased defect fill. Core biopsies showed ATB particles surrounded by newly formed bone and connective tissue. According to histomorphometric analysis, the harvested samples contained 56% of newly formed bone on average, and only a mean of 7% of non-remodelled ATB material was observed.ConclusionThe preliminary clinical, radiographical, and histological results of Bonmaker® autogenous tooth graft therapy indicate that ATB may be safely and successfully used as a grafting material for ARP. Optimal graft incorporation and histologically proven effective remodelling, as well as uneventful wound healing support the clinical application of ATB to minimize post-extraction hard tissue loss. Further research is needed to exploit the full potential of ATB and to evaluate the long-term peri-implant hard and soft tissue stability of ATB-treated post-extraction sites.

Three-dimensional assessment of the extraction sockets, augmented with platelet-rich fibrin and calcium sulfate: A clinical pilot study

ObjectivesThis clinical study assessed and compared the linear and volumetric changes of extraction sockets grafted with a combination of Platelet-Rich Fibrin (PRF) and Calcium Sulfate (CS) (PRF-CS), and extraction sockets grafted with a combination of PRF and xenograft (X) (PRF-X). MethodsFive single maxillary premolar extraction sockets received PRF-CS grafts and five single maxillary premolar sockets received PRF-X grafts. Linear (horizontal and vertical) measurements were accomplished using Cone Beam Computed Tomography (CBCT) images and volumetric changes were assessed using MIMICS software. Soft tissue level changes were measured using Stonecast models. All measurements were recorded at baseline (before extraction) and at 5-months post-extraction. ResultsSignificant reduction in vertical and horizontal dimensions were observed in both groups except for distal bone height (DBH = 0.44 ± 0.45 mm, p = 0.09) and palatal bone height (PBH = 0.39 ± 0.34 mm, p = 0.06) in PRF-X group. PRF-CS group demonstrated mean horizontal shrinkage of 1.27 ± 0.82 mm (p = 0.02), when compared with PRF-X group (1.40 ± 0.85 mm, p = 0.02). Vertical resorption for mesial bone height (MBH = 0.56 ± 0.25 mm, p = 0.008), buccal bone height (BBH = 1.62 ± 0.91 mm, p = 0.01) and palatal bone height (PBH = 1.39 ± 0.87 mm, p = 0.02) in PRF-CS group was more than resorption in PRF-X group (MBH = 0.28 ± 0.14 mm, p = 0.01, BBH = 0.63 ± 0.39 mm, p = 0.02 and PBH = 0.39 ± 0.34 mm, p = 0.06). Volumetric bone resorption was significant within both groups (PRF-CS = 168.33 ± 63.68 mm3, p = 0.004; PRF-X = 102.88 ± 32.93 mm3, p = 0.002), though not significant (p = 0.08) when compared between groups. In PRF-X group, the distal soft tissue level (DSH = 1.00 ± 0.50 mm, p = 0.03) demonstrated almost 2 times more reduction when compared with PRF-CS group (DSH = 1.00 ± 1.00 mm, 0.08). The reduction of the buccal soft tissue level was pronounced in PRF-CS group (BSH = 2.00 ± 2.00 mm, p = 0.06) when compared with PRF-X group (BSH = 1.00 ± 1.50 mm, p = 0.05). ConclusionsPRF-CS grafted sites showed no significant difference with PRF-X grafted sites in linear and volumetric dimensional changes and might show clinical benefits for socket augmentation.The study is officially registered with ClinicalTrials.gov Registration (NCT03851289).

Novel design of a Si3N4/BaO–Al2O3–SiO2 coating with a heterogeneous-layer structure on porous Si3N4 ceramic

During the preparation of coatings on porous Si3N4 ceramics, stress cracks often occur due to the sintering mismatch between the coating and substrate. To solve this problem, in this work, a Si3N4/BaO–Al2O3–SiO2 (BAS) coating with a heterogeneous-layer structure was designed and prepared, and the problem of sintering mismatch was effectively solved by suppressing the horizontal shrinkage of the coating. First, to verify the feasibility of the design, thin slices were prepared by alternately stacking the Si3N4 and BAS layers. The results showed that the thin slices prepared at 1550 °C had a dense and uniform morphology. During sintering, the liquid phase formed in the BAS layers infiltrated into the adjacent Si3N4 layers that can not only promote the densification but suppress the horizontal shrinkage of the Si3N4 layers. The largest vertical shrinkage rate of thin slices was 47.30% while the horizontal shrinkage rates were less than 2%. Based on these results, the coating with a heterogeneous-layer structure was prepared by alternately spraying Si3N4 and BAS slurries on porous Si3N4. The strength of interfacial bonding between the coating and substrate was 16.60 MPa, and the water absorption and Vickers hardness were 4.07% and 3.02 GPa, respectively. Conversely, the coating with a homogeneous structure prepared by the same spraying parameters displayed numerous macroscopic cracks. This study provides a novel design for the structure of the coating and promotes the application of porous Si3N4 ceramics in extreme environments.

Coupling of electrochemical\u2013temperature\u2013mechanical processes in marine clay during electro-osmotic consolidation

Electro-osmotic consolidation has been applied in several geotechnical engineering applications that contain a series of complex processes, including electrochemical processes, temperature changes, and mechanical evolution. To explore the combination of electrochemical–temperature–mechanical processes in marine clay, electro-osmotic consolidation experiments were conducted using a self-made electro-osmotic consolidation system under various durations and voltages. The following findings was obtained: (1) the change in the pH value increased during electro-osmotic consolidation and as the voltage rise; (2) the temperature increased with a rise in voltage in the initial stage of the experiments, which was induced by Joule heating; (3) the temperature rise promoted the electro-osmotic consolidation process, which included a rise in the coefficient of consolidation and a reduction in water content; (4) horizontal shrinkage occurred when the horizontal stress increment was greater than the critical stress condition. In addition, the volume difference reached a constant value, and was proportional to the voltage rise. After the discussion, a coupling analysis was conducted, which can help to better understand the mechanism of electro-osmotic consolidation and can provide reference for engineering applications.

Mold replication in injection molding of high density polyethylene

AbstractIn order to deepen the mechanisms at the basis of mold surface replication onto the molded plastic surface, a novel experimental approach is proposed. Up to 20 different mold surface textures were made by machining with repetitive patterns of peaks and valleys. Mold replication tests were performed by over‐molding of high density polyethylene (HDPE) on steel inserts. The surface morphology of inserts and injection molded parts was acquired by surface analyzer, and all the main roughness parameters were extracted and compared as well as the geometrical profiles. Surface morphology was also measured on molded samples after thermal relaxation at 100°C. As expected, a strong correlation was found between the roughness of mold insert and molded part over the full experimented range. Profiles on the molded surface have the same repetitive pattern of the corresponding insert surface but with lower peaks, higher valleys, and a horizontal shrinkage. Comparing molded HDPE surface profiles before and after thermal relaxation, it was observed a similar change to the one highlighted between mold insert and molded part. This occurrence suggests that the final surface appearance of the molded part is also a function of the relaxation mechanism during or immediately after injection molding.

A one-year prospective study on alveolar ridge preservation using collagen-enriched deproteinized bovine bone mineral and saddle connective tissue graft: A cone beam computed tomography analysis.

Although there is ample research on alveolar ridge preservation (ARP), changes of the soft tissue profile are seldom reported. In addition, the use of a saddle connective tissue graft (S-CTG) has only been described in one study. To evaluate changes in bone and external soft tissue profile following ARP of intact and nonintact sockets using collagen-enriched deproteinized bovine bone mineral (C-DBBM) and a S-CTG (a); to assess the need for additional hard and soft tissue grafting after ARP (b). Patients in need of a single or multiple unit fixed reconstruction in the premaxilla were included in this prospective case series. After tooth extraction, sockets were grafted with C-DBBM and sealed with a S-CTG. Cone beam computed tomography slides taken before tooth extraction and 4 to 6 months after ARP were superimposed to measure changes in bone dimensions and external soft tissue profile. The need for additional hard and soft tissue grafting was registered. Implants were evaluated at 1 year. Patient-reported outcomes were registered on a 100 mm visual analogue scale at suture removal and 1 year following ARP. Nineteen teeth (10 with intact sockets, 9 with nonintact sockets) in 14 patients (11 females; mean age 34) were extracted and treated with the abovementioned protocol. Volume loss could not be prevented and mainly occurred at the buccal aspect. Maximum horizontal bone resorption was 1.27 mm and maximum horizontal shrinkage of the soft tissue profile amounted to 0.87 mm, both at the most cervical aspect. Additional GBR was necessary in two sites with a nonintact buccal bone wall. The need for additional soft tissue grafting was moderate in sites with intact (3/10) and high in nonintact sockets (6/9). Implants demonstrated favorable clinical and esthetic outcomes. Pain intensity and patient satisfaction were 17 and 94, respectively. Alveolar ridge preservation was not able to prevent relevant tissue changes. However, implants could be installed as planned. Although the application of a S-CTG partly compensated for the buccal bone loss, the need for additional soft tissue grafting was still moderate in intact sockets and high in nonintact sockets.

Compression behavior of the graded metallic auxetic reentrant honeycomb: Experiment and finite element analysis

In this paper, the quasi-static compression behavior of graded metallic auxetic reentrant honeycomb was firstly studied. Using the selective laser melting method, the unidirectionally-graded auxetic honeycomb (UGAH) and bidirectionally-graded auxetic honeycomb (BGAH) with the equal mass were fabricated to conduct the compression tests. The deformation mode, crushing stress and Poisson's ratio distribution of graded auxetic honeycombs were presented. Experiment results showed that the compression behavior of graded auxetic honeycomb was different from that of graded honeycomb with positive Poisson's ratio owing to the horizontal shrinkage deformation and the gradient distribution had effects on the crushing stress and Poisson's ratio. Then, a finite element (FE) model of the graded auxetic honeycomb was established and the calculation results were systematically compared with the experimental results. The effects of gradient distribution on the energy dissipation characteristics of the graded auxetic honeycomb were studied. The results showed that the energy dissipation of the UGAH was lower than that of the BGAH before the graded layer with the maximum cell-wall thickness was densified.

Immediate implant placement combined with maxillary sinus floor elevation utilizing the transalveolar approach and nonsubmerged healing for failing teeth in the maxillary molar area: A randomized controlled trial clinical study with one-year follow-up.

In previous studies, immediate implant placement in molar sites has been widely applied. To study the clinical effect and feasibility of immediate implant placement combined with maxillary sinus floor elevation utilizing the transalveolar approach and nonsubmerged healing for failing teeth in the maxillary molar area. Patients who required implantation surgry to replace a failing tooth in the maxilla molar region were selected. Patients were randomized into two groups: immediate implant placement combined with maxillary sinus floor elevation utilizing the transalveolar approach and nonsubmerged healing (test group) or delayed implant placement combined with maxillary sinus floor elevation utilizing the transalveolar approach and nonsubmerged healing (control group). The outcome criteria were the success rates of implants, Cone Beam Computer Tomography (CBCT) data and results of the subjective satisfaction survey performed with a visual analog scale (VAS). All implants had good initial stability after implantation. The survival rate of implants was 100% at 1-year follow-up. At the time of permanent restoration, the differences in average horizontal shrinkage of alveolar bone (W1) on the buccal side between the test group (0.65 ± 0.12 mm) and the control group (1.23 ± 0.32 mm) were statistically significant (P < .0001); however, no statistically significant difference (P = .515) was observed on the palatal side (0.3 ± 0.10 mm vs 0.28 ± 0.08 mm). The difference in vertical resorption of alveolar bone (H1) on the buccal side between the test group (0.60 ± 0.18 mm) and the control group (1.53 ± 0.19 mm) was statistically significant (P < .0001), but no statistically significant difference (P = .190) in the reduction of palatal alveolar bone (0.24 ± 0.12 mm vs 0.29 ± 0.13 mm) was observed. After 1-year loading, no statistically significant difference (P > .05) in vertical or horizontal changes (W2, H2) were identified in the test group or control group. Patient satisfaction in both groups was similar (8.36 ± 1.01 vs 8.14 ± 1.35), and the difference between groups was not statistically significant (P = .638). Immediate implant placement combined with maxillary sinus floor elevation utilizing the transalveolar approach and nonsubmerged healing is feasible for the maxillary molar area, and the clinical effect is satisfactory.

A Novel and Facile Method for Characterizing Shrinkage Geometry along the Granitic Soil Profile

Core Ideas A simple and facile approach was proposed for measuring the anisotropic shrinkage. Subsidence was dominant for soils in the loose and aggregated structure. Horizontal shrinkage was predominant for soils with the horizontal arrangement of plate particles The shrinkage behavior of granite soils was controlled by clay content and pore structure. Soil volume change resulting from frequent drying–wetting cycles leads to severe erosion and landslides in granite regions. Limited attempts have been made to investigate the shrinkage geometry of these soils. Here, a new method was proposed for characterizing soil shrinkage behavior by testing cylindrical specimens of undisturbed granitic soils sampled separately in vertical and horizontal directions at the pedogenic layers (i.e., surface [L1], lateritic [L2 and L3], sandy [L4], and detritus [L5] layers). For L1, the coefficient of linear extensibility (COLE) was larger in the vertical than in the horizontal direction, whereas it was the opposite for L2 and L3. For L4 and L5, the COLE showed no significant differences between the two directions. A modified van Genuchten equation fitted well with the COLE curves (p &lt; 0.01). The shrinkage potential decreased in the order of L3 &gt; L2 &gt; L1, L4 &gt; L5. Subsidence was dominant for the L1 soil due to the loose‐aggregated structure, whereas cracking was dominant in the lateritic layer soils due to the horizontal arrangement of clay particles. The shrinkage geometry for L4 and L5 was largely determined by soil structure inherited from the configuration of granite rock. The shrinkage behavior of granite soils was controlled by clay content and pore structure. This new method of measuring shrinkage geometry is accurate, low cost, nondestructive, and labor saving but remains to be improved and validated on a wide range of soil types.