Influence of Repeated Cut-off and Rescanning on the Trueness of the Intraoral Digital Scans.

OBJECTIVES: To evaluate the effects of repeated cut-off and rescan procedures on the trueness of three intraoral scanners (IOS). METHODS: A tooth model (#16) with a standard class II cavity was prepared, and the complete-arch was scanned using a laboratory scanner (D2000, 3Shape A/S) to obtain a reference scan. Then the typodont was scanned with three IOSs (3Shape TRIOS 3, CEREC Omnicam, and Medit i500) under two rescanning strategies (full-cut and partial-cut), with varying numbers of repeated cut-off and rescanning procedures (0, 1, 3, 5, 7, or 10). The trueness discrepancy between the reference and experimental digital scan was estimated using root mean square (RMS) calculations. Three regions of interest were selected to represent the rescanning, identification, and non-rescan area. And the discrepancies were analyzed using a linear mixed model (α=.05). RESULTS: Cut-off and rescanning procedures significantly decreased the trueness of digital scans in all test conditions compared to the reference. However, no progressive increase in discrepancy was observed under any rescan conditions. Significant influences on trueness were found based on the IOS used, with the 3Shape system exhibiting lower RMS values. The partial-cut strategy showed lower RMS values compared to the full-cut strategy, albeit without statistical significance. CONCLUSIONS: While repeated cut-off and rescanning procedures led to a decline in the quality of digital impressions, they did not result in discrepancy accumulation with repeated rescanning. CLINICAL SIGNIFICANCE: To ensure high scanning accuracy in dental practice, it is advisable to minimize the rescanning area when correcting imperfections in digital scans. Additionally, selecting an appropriate scanner can help mitigate the negative effects of the rescanning technique.

High internal phase pickering emulsions stabilized by zein/whey protein nanofibril complexes: Preparation and lycopene loading.

High internal phase Pickering emulsions (HIPPEs) prepared from natural polymers have attracted much attention in the food manufactures. However, single zein-stabilized HIPPEs are poorly stable and prone to flocculation near the isoelectric point. To address this issue, in this study, zein and whey protein nanofibrils (WPN) complex nanoparticles (ZWNPs) were successfully prepared using a pH-driven method, and ZWNPs were further used as HIPPEs stabilizers. The results showed that zein and WPN were combined together through hydrogen bonding and hydrophobic interaction to form ZWNPs, and the HIPPEs stabilized by ZWNPs had excellent stability, which could effectively protect the internally encapsulated lycopene and improve the bioaccessibility of lycopene. In conclusion, this study provides a new strategy for the preparation of stable hydrophobic protein-based HIPPEs, represented by zein.

Effects of cubic ecological restoration of mining wasteland and the preferred restoration scheme.

In view of the strong acidity and high heavy metal contents of the soil, the low vegetation cover, and strong soil erosion caused by mining activities, the reasonable determination of the cubic restoration mode is the key to determining the good or bad ecological restoration effects on mining wasteland. In this study, based on field experiments, a combined cubic ecological restoration scheme for soil improvement-vegetation reconstruction was constructed. Using analysis of variance, a regression model, and the Mantel test, the differences in soil properties and the biodiversity were analyzed under different restoration schemes, the entropy-weighted-TOPSIS method was used to optimize the best ecological restoration model. The results revealed that compared with the pre-restoration state, the restoration significantly increased the soil pH (p < 0.05) by 4.07-5.73, regulated the strong acidic environment of the soil, increased the organic matter content by 5.35-11.21 times, and improved the soil fertility. The available contents of Pb and Cd were reduced by 67.15-75.58 % and 64.15-88.68 %, respectively compared with the background values. Biodiversity improved significantly, and the available content of Cd was an important factor in the biodiversity recovery. The evaluation of the effect of the restoration scheme showed that the combination of mixed soil amendments of rice husks and chicken manure (10 kg/m2), bacterial fertilizer (1.8 kg/m2), biochar (1.3 kg/m2), lime (8.3 kg/m2), and soil conditioner (1.0 kg/m2) and tolerant plants (Pinus elliottii, Lagerstroemia indica, and Plantago asiatica) are the optimal cubic ecological restoration scheme for the study area, with a plant survival rate of > 90 %, eight families and 10 species of plants, and a coverage rate of 100 %. These research results provide a scientific basis and technical support for reasonable artificial intervention in ecological restoration of mining waste sites in Nanling, northern Guangdong.

Moisture spectral characteristics and hyperspectral inversion of fly ash-filled reconstructed soil.

To explore problems with the fast estimation method of moisture content (MC) in reconstructed soil under human disturbance, this paper used a fly ash-filled reconstructed soil region as the research object and obtained experimental data by Fieldspec4 high spectrometry and the laboratory drying method. The response characteristics of MC were analyzed from the original spectral data that underwent mathematical transformation and the spectral index data, and a corresponding inversion model was established. Combined with the successive projections algorithm (SPA), the model was optimized with a better fitting effect, and the optimal inversion model was obtained. The results showed that the composition of soil and fly ash were different, resulting in obvious differences in the shape of the spectral curve, but both had large moisture absorption peaks near 1420 nm and 1920 nm. After mathematical transformation, the correlation between the spectral reflectance and MC was enhanced, in which the absolute value of the maximum correlation between the soil moisture content (SMC) was 0.839, and the absolute value of the maximum correlation between the fly ash moisture content (FMC) was 0.801. Among them, the first-order differential of multivariate scattering correction (MSC') and the first-order differential of logarithm ((lgR)') had higher fitting accuracy for FMC and SMC, respectively. The scale and sensitivity of significance variables were greatly improved based on the spectral index of two-band operation. Better FMC and SMC models were constructed based on the difference soil index (DSI) under mathematical transformation, and R2 were 0.73 and 0.87, respectively. After SPA optimization, the predictive ability of the model was further improved, in which the predictive accuracy R2 of FMC and SMC reached up to 0.87 and 0.96, respectively, and the RPD was greater than 3. This shows that the DSI model based on MSC' and (lgR)' combined with the SPA method can be used as an effective means of predicting the MC in fly ash-filled reconstructed soil. These research results provide the theoretical basis and technical support for the application of soil near-earth sensing technology and rapid estimation of the MC of reconstructed soil under human disturbance.

Cross Photoreaction of Glyoxylic and Pyruvic Acids in Model Aqueous Aerosol.

Aerosols of variable composition, size, and shape are associated with public health concerns as well as with light-particle interactions that play a role in the energy balance of the atmosphere. Photochemical reactions of 2-oxocarboxylic acids in the aqueous phase are now known to contribute to the total secondary organic aerosol (SOA) budget. This work explores the cross reaction of glyoxylic acid (GA) and pyruvic acid (PA) in water, the two most abundant 2-oxocarboxylic acids in the atmosphere, under solar irradiation and dark thermal aging steps. During irradiation, PA and GA are excited and initiate proton-coupled electron transfer or hydrogen abstraction and α-cleavage reactions, respectively. The time series of photoproducts is studied by ion chromatography (IC) with conductivity and electrospray ionization (ESI) mass spectrometry (MS) detection, direct ESI-MS analysis in the negative ion mode, and nuclear magnetic resonance spectroscopy (NMR). The use of one-dimensional (1H and 13C NMR) and two-dimensional NMR techniques includes gradient correlation spectroscopy (gCOSY) and heteronuclear single quantum correlation (HSQC). The aging of photoproducts in the dark is monitored by UV-visible spectroscopy. The periodicity in the time domain of the optical properties is explained in terms of chromophores that undergo alternating thermochromism and photobleaching between nighttime and daytime cycles, respectively. A reaction mechanism for the cross reaction of GA and PA explaining the generation of trimers with general formulas C5H8O5 (148 Da), C6H10O5 (162 Da), and C5H8O6 (164 Da) is provided based on all experimental observations.

Dolyemycins A and B, two novel cyclopeptides isolated from Streptomyces griseus subsp. griseus HYS31.

Two novel cyclopeptides with special skeleton, namely, dolyemycins A (1) and B (2) were isolated from Streptomyces griseus subsp. griseus HYS31 by bio-guided isolation. Their structures were elucidated by detailed analysis of spectroscopic data. These two compounds were cyclopeptides containing eleven amino acids including five unusual amino acids (hydroxyglycine, 3-hydroxyleucine, 3-phenylserine, ß-hydroxy-O-methyltyrosine, 2,3-diaminobutyric acid) in both of them and an extra nonprotein amino acids (3-methylaspartic acid) in Dolyemycin B only. Dolyemycins A and B performed antiproliferative activity against human lung cancer A549 cells with IC50 values of 1.0 and 1.2 µM, respectively.

Aqueous Photochemistry of Glyoxylic Acid.

Aerosols affect climate change, the energy balance of the atmosphere, and public health due to their variable chemical composition, size, and shape. While the formation of secondary organic aerosols (SOA) from gas phase precursors is relatively well understood, studying aqueous chemical reactions contributing to the total SOA budget is the current focus of major attention. Field measurements have revealed that mono-, di-, and oxo-carboxylic acids are abundant species present in SOA and atmospheric waters. This work explores the fate of one of these 2-oxocarboxylic acids, glyoxylic acid, which can photogenerate reactive species under solar irradiation. Additionally, the dark thermal aging of photoproducts is studied by UV-visible and fluorescence spectroscopies to reveal that the optical properties are altered by the glyoxal produced. The optical properties display periodicity in the time domain of the UV-visible spectrum of chromophores with absorption enhancement (thermochromism) or loss (photobleaching) during nighttime and daytime cycles, respectively. During irradiation, excited state glyoxylic acid can undergo α-cleavage or participate in hydrogen abstractions. The use of (13)C nuclear magnetic resonance spectroscopy (NMR) analysis shows that glyoxal is an important intermediate produced during direct photolysis. Glyoxal quickly reaches a quasi-steady state as confirmed by UHPLC-MS analysis of its corresponding (E) and (Z) 2,4-dinitrophenylhydrazones. The homolytic cleavage of glyoxylic acid is proposed as a fundamental step for the production of glyoxal. Both carbon oxides, CO2(g) and CO(g) evolving to the gas-phase, are quantified by FTIR spectroscopy. Finally, formic acid, oxalic acid, and tartaric acid photoproducts are identified by ion chromatography (IC) with conductivity and electrospray (ESI) mass spectrometry (MS) detection and (1)H NMR spectroscopy. A reaction mechanism is proposed based on all experimental observations.