PCDNF: Revisiting Learning-based Point Cloud Denoising via Joint Normal Filtering.

Point cloud denoising is a fundamental and challenging problem in geometry processing. Existing methods typically involve direct denoising of noisy input or filtering raw normals followed by point position updates. Recognizing the crucial relationship between point cloud denoising and normal filtering, we re-examine this problem from a multitask perspective and propose an end-to-end network called PCDNF for joint normal filtering-based point cloud denoising. We introduce an auxiliary normal filtering task to enhance the network's ability to remove noise while preserving geometric features more accurately. Our network incorporates two novel modules. First, we design a shape-aware selector to improve noise removal performance by constructing latent tangent space representations for specific points, taking into account learned point and normal features as well as geometric priors. Second, we develop a feature refinement module to fuse point and normal features, capitalizing on the strengths of point features in describing geometric details and normal features in representing geometric structures, such as sharp edges and corners. This combination overcomes the limitations of each feature type and better recovers geometric information. Extensive evaluations, comparisons, and ablation studies demonstrate that the proposed method outperforms state-of-the-art approaches in both point cloud denoising and normal filtering.

Study on the Influence of Weld Spacing on the Tensile Strength of Laser Double-Pass Reciprocating Welding of DP780/6061-T6 Dissimilar Metals.

The welding of steel-aluminum dissimilar metals plays a vital role in promoting automobile lightweight. However, it is tricky to obtain good mechanical properties of steel-aluminum laser weldments. Based on the principle of preheating welding, the laser double-pass reciprocating welding method of steel-aluminum dissimilar metals was proposed. In the experiment, different weld spacing such as 0, 0.5, 1.0, 1.5, and 2.0 mm were set, and numerical calculations of the temperature field of the molten pool were carried out. The results show that the tensile strength of weldment depends on the mechanical properties of the second weld seam in the optimal welding parameters. Compared with other weld spacing, when the weld spacing is 1.5 mm, the preheating temperature, peak temperature, and pool width on the steel side of the second weld are lower. In contrast, the weld penetration's peak value and molten pool center's temperature reach the maximum on the aluminum side. The thickness of the steel/aluminum transition layer changed from 14 to 11 to 8 µm with increased weld spacing. Moreover, the fracture mode of the second weld is a ductile fracture. Furthermore, the average tensile strength can reach 76.84 MPa. The results show that appropriate weld spacing and preheating temperature can effectively improve the tensile strength of the welding joint.

Facile Synthesis of In Situ Formable Alginate Composite Hydrogels with Ca2+-Induced Healing Ability.

Dental caries have plagued humans for many years. At present, photocrosslinking resin is commonly used in clinics to repair narrow tooth defects, but the ultraviolet light used in this process has unavoidable cytotoxicity. In situ hydrogels with a similar structure to that of the natural extracellular matrix have gradually attracted attention in the field of hard tissue repair engineering. The injectable molding properties of hydrogel also give it the potential to fill irregularly shaped or fine tissue defects. Through a rapid and facile Michael addition reaction, we prepared maleic chitosan (CS-maleic anhydride [MA]) and thiolated alginate (sodium alginate [SA]-SH) to form a CS-MA/SA-SH hydrogel. To endue its mineralize ability, ß-glycerophosphate calcium phosphate and calcium carbonate as the precursor of hydroxyapatite (HAp) were premixed in the hydrogel at certain ratios. This kind of hydrogel can quickly form into different shapes within 10 min. It is worth noting that external Ca2+ can react with the residual carboxyl groups of SA and provide the hydrogel with a self-healing ability. At the same time, we creatively propose a method that uses alkaline phosphatase to promote the mineralization of HAp in hydrogels, to achieve the purpose of regenerating hard tissue in situ. By examining the properties of hydrogels at different concentrations of calcium and phosphorus salts, we find that the CS-MA/SA-SH hydrogel with 50% (wt.%) inorganic matter presented the best self-healing properties, excellent mineralization of highly crystallized Hap, and has ideal cell compatibility. The potential application of the CS-MA/SA-SH hydrogel in repairing exposed dentin tubules in decayed teeth was explored through preliminary in vitro dental restoration experiments. Obviously, the penetration depth through dentin tubules was better than that of commercial dental sensitizers. In addition, the HAp morphology was affected by the local environment. We believe that this hydrogel can utilize tissues for dental regeneration and mineralization, and the healing ability provides the hydrogel flexibility for further application in hard tissue regeneration. Impact statement In this article, we report a simple, gentle, and rapid method for the synthesis of new, in situ-formable polysaccharide-based hydrogels that are capable of healing through the Michael addition reaction, which does not require any crosslinking agents. The rapid healing ability of the hydrogel can be obtained within 1 min by introducing calcium ions, giving the hydrogel the possibility of self-healing in the cap-enriched state. Second, we conferred in vitro mineralization of hydrogels and used a simple novel "enzyme-promoted" approach. Simulated mineralization using human body-enriched alkaline phosphatase as an inducer, allowing hydrogels rich in calcium glycerophosphate and calcium chloride to be highly similar to natural hydroxyphospholipids in a simulated body fluid environment at 37°C, stone-structured, and well-shaped thin-section mineralized products. Finally, we use the self-healing hydrogel with in vitro mineralization ability to carry out simple repair and mineralization regeneration of enamel and dentin, and this result is related to the tooth desensitizing agent commonly used in Chinese dental clinics. Comparison of commercial hydrogels further proves that this polysaccharide-based hydrogel is not only convenient for clinical operation in oral prosthesis but also has obvious advantages in the sealing of enamel by dental tubules and the enhancement of tooth hardness.

Histatin1-modified thiolated chitosan hydrogels enhance wound healing by accelerating cell adhesion, migration and angiogenesis.

It is urgently needed for effective treatments of extensive skin loss, wherein lack of angiogenesis is a major obstacle. In this study, we present a thermosensitive thiolated chitosan (CSSH) hydrogel conjugated with Histatin1 (Hst1) as a wound dressing to study its efficacy in enhancing the cell adhesion, spreading, migration, and angiogenesis. The composite hydrogels with gelation time of 5-7 min, showed a prolonged release of Hst1. Cell culture indicated that the adhesion, spreading, migration and tubule formation of HUVECs were promoted, especially for the Hst1-H group. The in vivo healing evaluation showed that the rate of recovery in Hst1-H group was increased to 84% at day 7, and the CD31 positive cells, vascular endothelial growth factor (VEGF) positive cells and aligned collagen fibers were significantly more than the controlled groups. Therefore, CSSH/Hst1 hydrogel is a promising candidate for wound healing by accelerating cell adhesion, migration and angiogenesis.

Poly(L-lactide)/halloysite nanotube electrospun mats as dual-drug delivery systems and their therapeutic efficacy in infected full-thickness burns.

In this study, poly(L-lactide) (PLLA)/halloysite nanotube (HNT) electrospun mats were prepared as a dual-drug delivery system. HNTs were used to encapsulate polymyxin B sulphate (a hydrophilic drug). Dexamethasone (a hydrophobic drug) was directly dissolved in the PLLA solution. The drug-loaded HNTs with optimised encapsulation efficiency were then mixed with the PLLA solution for subsequent electrospinning to form composite dual-drug-loaded fibre mats. The structure, morphology, degradability and mechanical properties of the electrospun composite mats were characterised in detail. The results showed that the HNTs were uniformly distributed in the composite PLLA mats. The HNTs content in the mats could change the morphology and average diameter of the electrospun fibres. The HNTs improved both the tensile strength of the PLLA electrospun mats and their degradation ratio. The drug-release kinetics of the electrospun mats were investigated using ultraviolet-visible spectrophotometry. The HNTs/PLLA ratio could be varied to adjust the release of polymyxin B sulphate and dexamethasone. The antibacterial activity in vitro of the mats was evaluated using agar diffusion and turbidimetry tests, which indicated the antibacterial efficacy of the dual-drug delivery system against Gram-positive and -negative bacteria. Healing in vivo of infected full-thickness burns and infected wounds was investigated by macroscopic observation, histological observation and immunohistochemical staining. The results indicated that the electrospun mats were capable of co-loading and co-delivering hydrophilic and hydrophobic drugs, and could potentially be used as novel antibacterial wound dressings.

Effect of ovariectomy on serum adiponectin levels and visceral fat in rats.

This study was aimed to examine the effect of ovariectomy on visceral fat, serum adiponectin levels and lipid profile. Forty-five female Sprague Dawley rats were divided into three groups (n=15 each): ovariectomized group (OVX), ovariectomized plus estrogen-treated group (OVX+E2), and sham-operated group (SHAM). Body weight, abdominal adipose tissues, serum adiponectin and lipid profile were measured and compared among the groups after three-month feeding post-surgery. Significant increases in body weight and visceral fat were found in ovariectomized rats when compared with sham-operated ones and significant increases were also observed in serum adiponectin, triglyceride and very low density lipoprotein cholesterol levels in ovariectomized rats. Body weight, visceral fat and serum adiponectin levels were profoundly reduced in OVX+E2 group as compared with OVX group. It was concluded that ovarian hormone deficiency induced by ovariectomy leads to significant increases in body weight and visceral fat, along with increased serum adiponectin, triglyceride and very low density lipoprotein cholesterol levels in rats. Attenuation in these changes can be achieved by estrogen supplementation.

Evaluation of oral subchronic toxicity of Pu-erh green tea (camellia sinensis var. assamica) extract in Sprague Dawley rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Pu-erh green tea, originally produced in the Yunnan province of P.R. China for about 1700 years, is believed to be beneficial to health in Asian countries. The potential toxicity of Pu-erh green tea when administered at high doses via concentrated extract, however, has not been completely investigated. THE AIM OF THE STUDY: The present study was aimed to evaluate the potential toxicity of Pu-erh green tea extract (PGTE) of sub-chronic administration to Sprague Dawley (SD) rats. MATERIALS AND METHODS: Growing SD rats were administrated orally by gavage with PGTE at doses of 0, 1250, 2500, and 5000 mg/kg/day for 91 consecutive days. Clinical observations, including survival, hematology, serum biochemistry, urinalysis and histopathological examination were measured to monitor treatment-related adverse effects in rats. RESULTS: The results showed that oral administration of high dose of PGTE led to body weight gain suppression, liver and calcium deposition dysfunctions. CONCLUSIONS: In conclusion, the no-observed-adverse-effect level for Pu-erh green tea extract derived from the results of the present study was 2500 mg/kg/day for both genders.