[Study on quantitative analysis of bracket-induced nonlinear response of labio-cheek soft tissue during the orthodontic process].

In the orthodontics process, intervention and sliding of an orthodontic bracket during the orthodontic process can arise large response of the labio-cheek soft tissue. Soft tissue damage and ulcers frequently happen at the early stage of orthodontic treatment. In the field of orthodontic medicine, qualitative analysis is always carried out through statistics of clinical cases, while quantitative explanation of bio-mechanical mechanism is lacking. For this purpose, finite element analysis of a three-dimensional labio-cheek-bracket-tooth model is conducted to quantify the bracket-induced mechanical response of the labio-cheek soft tissue, which involves complex coupling of contact nonlinearity, material nonlinearity and geometric nonlinearity. Firstly, based on the biological composition characteristics of labio-cheek, a second-order Ogden model is optimally selected to describe the adipose-like material of the labio-cheek soft tissue. Secondly, according to the characteristics of oral activity, a two-stage simulation model of bracket intervention and orthogonal sliding is established, and the key contact parameters are optimally set. Finally, the two-level analysis method of overall model and submodel is used to achieve efficient solution of high-precision strains in submodels based on the displacement boundary obtained from the overall model calculation. Calculation results with four typical tooth morphologies during orthodontic treatment show that: ① the maximum strain of soft tissue is distributed along the sharp edges of the bracket, consistent with the clinically observed profile of soft tissue deformation; ② the maximum strain of soft tissue is reduced as the teeth align, consistent with the clinical manifestation of common damage and ulcers at the beginning of orthodontic treatment and reduced patient discomfort at the end of treatment. The method in this paper can provide reference for relevant quantitative analysis studies in the field of orthodontic medical treatment at home and abroad, and further benefit to the product development analysis of new orthodontic devices.

Biosynthesis, characterization of PLGA coated folate-mediated multiple drug loaded copper oxide (CuO) nanoparticles and it's cytotoxicity on nasopharyngeal cancer cell lines.

Cytotoxicity of CuO nanoparticles (NPs) are an impediment in utilizing them as an effective nanocarriers of chemotherapeutic drugs for targeted drug delivery in nasopharyngeal cancer. In our current study, we have designed a two-step synthesis and coating of CuO NPs with different concentrations of PLGA (polylactide-co-glycolide) to reduce the cytotoxicity. This was further conjugated with folic acid to enhance targeting to specific tissue. The multiple drugs loaded in the NPs were two potent anticancer drugs doxorubicin and docetaxel. A complete characterization studies including micrographic analysis, zeta potential measurements, polydispersity index, Fourier transform infrared spectroscopy (FTIR), encapsulation and loading efficiencies, stability and in vitro release studies were done. Cytoxicity studies were done with MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, acridine orange/ethidium bromide and DAPI (4, 6-diamidino-2-phenylindole, dihydrochloride) staining procedures. Impediametric studies were also carried out to reinforce the reduction in cytotoxicity. Finally the cellular uptake of the NPs was seen. It was evident from the results that the multiple drugs loaded CuO NPs formed with PLGA coating were uniform, non-agglomerated in size ranging from 180 to 195 nm. The FTIR revealed no major changes in drug peaks. Encapsulation and loading efficiencies showed sufficient amount of drug being loaded into the NPs. The drug loaded NPs showed no change in size or zeta potential even after a period of 30 days. The cytotoxicity studies revealed significant reduction in toxicity after coating the surface treated with PLGA as evident from the microscopic analysis of cells. Hence the current study may be prioritized and further in vivo/in vitro studies may be carried out.

Effects of salt stress on eco-physiological characteristics in Robinia pseudoacacia based on salt-soil rhizosphere.

Robinia pseudoacacia is the main arbor species in the coastal saline-alkali area of the Yellow River Delta. Because most studies focus on the aboveground parts, detailed information regarding root functioning under salinity is scare. Root traits of seedlings of R. pseudoacacia including morphological, physiological and growth properties under four salinity levels (CK, 1‰, 3‰ and 5‰ NaCl) were studied by the pot experiments to better understand their functions and relationships with the shoots. The results showed that seedling biomass decreased by the reduction of root, stem and leaf biomass with the increase of salinity levels. With increasing salinity levels, total root length (TRL) and total root surface area (TRSA) decreased, whereas specific root length (SRL) and specific root area (SRA) increased. Salt stress decreased root activity (RA) and the maximum net photosynthetic rate (Amax) and increased the water saturation deficit (WSD) significantly in the body. Correlation analyses showed significantly correlations between root morphological and physiological parameters and seedling biomass and shoot physiological indexes. R. pseudoacacia seedlings could adapt to 1‰ salinity by regulating the root morphology and physiology, but failed in 5‰ salinity. How to adjust the water status in the body with decreasing water uptake by roots was an important way for R. pseudoacacia seedlings to adapt to the salt stress.