Accurate segmentation of oral surgery-related tissues from cone beam computed tomography (CBCT) images can significantly accelerate treatment planning and improve surgical accuracy. In this paper, we ...propose a fully automated tissue segmentation system for dental implant surgery. Specifically, we propose an image preprocessing method based on data distribution histograms, which can adaptively process CBCT images with different parameters. Based on this, we use the bone segmentation network to obtain the segmentation results of alveolar bone, teeth, and maxillary sinus. We use the tooth and mandibular regions as the ROI regions of tooth segmentation and mandibular nerve tube segmentation to achieve the corresponding tasks. The tooth segmentation results can obtain the order information of the dentition. The corresponding experimental results show that our method can achieve higher segmentation accuracy and efficiency compared to existing methods. Its average Dice scores on the tooth, alveolar bone, maxillary sinus, and mandibular canal segmentation tasks were 96.5%, 95.4%, 93.6%, and 94.8%, respectively. These results demonstrate that it can accelerate the development of digital dentistry.
We study the formation of Cu2ZnSnS4 (CZTS) films from various liquid-phase precursors. Our experimental data point to the significant role that reactivities of precursor components play in the ...quality of the final material. Although reactive molecular precursors favor formation of CZTS under milder conditions, the formation of large crystalline domains requires using less reactive nanostructured precursors. We explain this effect using kinetics of nucleation and growth. We have also demonstrated a strategy to effectively enhance grain growth of CZTS using solid-state phase transition as the driving force for nanocrystal sintering. We hope this contribution will provide a useful guide toward the rational design of liquid-phase precursors for inorganic semiconductors for electronic and optoelectronic applications.
Warpage is a typical defect for injection-molded parts, especially for crystalline parts molded by rapid heat cycle molding (RHCM). In this paper, a prediction method is proposed for predicting the ...warpage of crystalline parts molded by the RHCM process. Multi-layer models were established to predict warpage with the same thicknesses as the skin-core structures in the molded parts. Warpages were defined as the deformations calculated by the multi-layer models. The deformations were solved using the classical laminated plate theory by Abaqus. A model was introduced to describe the elastic modulus with the influence of temperature and crystallinity. The simulation process was divided into two procedures, before ejection and after ejection. Thermal stresses and thermal strains were simulated, respectively, in the procedure before ejection and after ejection. The prediction results were compared with the experimental results, which showed that the average errors between predicted warpage and average experimental warpage are, respectively, 7.0%, 3.5%, and 4.4% in conventional injection molding (CIM), in RHCM under a 60 °C heating mold (RHCM60), and in RHCM under a 90 °C heating mold (RHCM90).
A burn mark is a sort of serious surface defect on injection-molded parts. In some cases, it can be difficult to reduce the burn marks by traditional methods. In this study, external gas-assisted ...injection molding (EGAIM) was introduced to reduce the burn marks, as EGAIM has been reported to reduce the holding pressure. The parts with different severities of burn marks were produced by EGAIM and conventional injection molding (CIM) with the same molding parameters but different gas parameters. The burn marks were quantified by an image processing method and the quantitative method was introduced to discuss the influence of the gas parameters on burn marks. The results show that the burn marks can be eliminated by EGAIM without changing the structure of the part or the mold, and the severity of the burn marks changed from 4.98% with CIM to 0% with EGAIM. Additionally, the gas delay time is the most important gas parameter affecting the burn marks.
The chain conformation and individual chain structures of the graft copolymers ethyl cellulose grafting poly (acrylic acid) (EC-g-PAA) were investigated by laser light scattering (LLS) and atom force ...microscopy (AFM). The EC-g-PAA graft copolymers with two different side chain lengths and side chain grafting densities were synthesized via atom transfer radical polymerization (ATRP) from ethyl cellulose as the backbone. The graft copolymer molecules are adsorbed on the mica surface, and the observed single molecule structures by AFM reflect the molecular conformation in solution. An increase of the graft density of the graft copolymer induces the conformational transition due to the repulsion between side chains from coil to rod conformation. The observed disclike and rodlike single chain structures response to the coil and rod conformations, respectively. The results provide a direct visual experimental evidence of chain conformational and single chain structural transitions for graft copolymers in common solvents induced by graft density.
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The mitochondrial transcription factor A (TFAM) is required for mitochondrial DNA (mtDNA) replication and transcription. Disruption of TFAM results in heart failure and premature aging in mice. But ...very little is known about the role of TFAM in cancer development. Here, we report the identification of frequent frameshift mutations in the coding mononucleotide repeat of TFAM in sporadic colorectal cancer (CRC) cell lines and in primary tumors with microsatellite instability (MSI), but not in microsatellite stable (MSS) CRC cell lines and tumors. The presence of the TFAM truncating mutation, in CRC cells with MSI, reduced the TFAM protein level in vivo and in vitro and correlated with mtDNA depletion. Furthermore, forced overexpression of wild-type TFAM in RKO cells carrying a TFAM truncating mutation suppressed cell proliferation and inhibited RKO cell-induced xenograft tumor growth. Moreover, these cells showed more susceptibility to cisplatin-induced apoptosis due to an increase of cytochrome b (Cyt b) expression and its release from mitochondria. An interaction assay between TFAM and the heavy-strand promoter (HSP) of mitochondria revealed that mutant TFAM exhibited reduced binding to HSP, leading to reduction in Cyt b transcription. Collectively, these data provide evidence that a high incidence of TFAM truncating mutations leads to mitochondrial copy number reduction and mitochondrial instability, distinguishing most CRC with MSI from MSS CRC. These mutations may play an important role in tumorigenesis and cisplatin-induced apoptotic resistance of most microsatellite-unstable CRCs.
A pH-sensitive gold nanoparticle-cysteamine/carboxymethyl cellulose (Au-CA/CMC) dispersion system was prepared by a simple approach. Gold nanoparticles (AuNPs) were first synthesized by directly ...reducing chloroauric acid (HAuCl4) with sodium carboxymethyl cellulose (CMC). Then the AuNPs were decorated by an electrostatic compound of cysteamine hydrochloride (CA) and sodium carboxymethyl cellulose (CMC) through ligand exchange to get the assembly of Au-CA/CMC. The Au-CA/CMC dispersion system exhibits strongly reversible pH-responsive behavior with the aggregation of AuNPs caused by the combined action of the chain conformation change of CMC and electrostatic interactions between CA and CMC at different pH values. Finally, the reversible aggregation mechanism of AuNPs in the Au-CA/CMC dispersion system has been investigated by transmission electron microscopy (TEM) and ultraviolet−visible spectroscopy (UV−vis spectroscopy). This study provides a new method to fabricate a stimuli-responsive system free from complicated organic synthesis without using a toxic reducing agent.
We examine the stability of excitons in quantum-confined InP nanocrystals as a function of temperature elevation up to 800 K. Through the use of static and time-resolved spectroscopy, we find that ...small inorganic capping ligands substantially improve the temperature dependent photoluminescence quantum yield relative to native organic ligands and perform similarly to a wide band gap inorganic shell. For this composition, we identify the primary exciton loss mechanism as electron trapping through a combination of transient absorption and transient photoluminescence measurements. Density functional theory indicates little impact of studied inorganic ligands on InP core states, suggesting that reduced thermal degradation relative to organic ligands yields improved stability; this is further supported by a lack of size dependence in photoluminescence quenching, pointing to the dominance of surface processes, and by relative thermal stabilities of the surface passivating media. Thus, small inorganic ligands, which benefit device applications due to improved carrier access, also improve the electronic integrity of the material during elevated temperature operation and subsequent to high temperature material processing.
In order to improve the performance of traditional sodium alginate (SA) hydrogels cross-linked by Ca
ions to meet greater application demand, a strategy was designed to structure novel SA-based gels ...(named OP-PN gels) to achieve both stimulus responsiveness and improved mechanical strength. In this strategy, the SA chains are co-cross-linked by CaCl₂ and cationic octa-ammonium polyhedral oligomeric silsesquioxane (Oa-POSS) particles as the first network, and an organically cross-linked poly(N-isopropyl acrylamide) (PNIPA) network is introduced into the gels as the second network. Several main results are obtained from the synthesis and characterization of the gels. For OP-PN gels, their properties depend on the content of both uniformly dispersed Oa-POSS and PNIPA network directly. The increased Oa-POSS and PNIPA network content significantly improves both the strength and resilience of gels. Relatively, the increased Oa-POSS is greatly beneficial to the modulus of gels, and the increased PNIPA network is more favorable to advancing the tensile deformation of gels. The gels with hydrophilic PNIPA network exhibit better swelling ability and remarkable temperature responsiveness, and their volume phase transition temperature can be adjusted by altering the content of Oa-POSS. The deswelling rate of gels increases gradually with the increase of POSS content due to the hydrophobic Si⁻O skeleton of POSS. Moreover, the enhanced drug loading and sustained release ability of the target drug bovine serum albumin displays great potential for this hybrid gel in the biomedical field.
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