Tag: statistics

Polymers (Basel). 2022 Apr 29;14(9):1831. doi: 10.3390/polym14091831.

ABSTRACT

Knowledge of the chemical-physical reactions that determine the main degradation behaviour of artists’ alkyd paints represents one of the main problems within the museum exhibitions. The collection and interpretation of these data on degradation phenomena, especially after ozone exposure at different relative humidity values, can be useful for their conservation needs. Therefore, a systematic investigation of these materials may help achieve this goal. Firstly, surface-level identification of the main functional groups of ad hoc created and aged alkyd paints was performed using attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR). Subsequently, these paints were investigated by pyrolysis-gas chromatography and mass spectrometry (Py-GC/MS), allowing for precise bulk identification of the organic compounds before and after accelerated ageing. A first successful attempt to provide quantitative Py-GC/MS data on alkyd-based paints is here presented and discussed. Comparing the results, it was possible to obtain new insights into the degradation behaviour of alkyd paints when exposed to ozone, allowing us to devise specific preventive and conservation strategies for these artistic materials.

PMID:35566997 | DOI:10.3390/polym14091831

Polymers (Basel). 2022 Apr 27;14(9):1787. doi: 10.3390/polym14091787.

ABSTRACT

The knowledge of the atmospheric degradation reactions affecting the stability of modern materials is still of current interest. In fact, environmental parameters, such as relative humidity (RH), temperature, and pollutant agents, often fluctuate due to natural or anthropogenic climatic changes. This study focuses on evaluating analytical and statistical strategies to investigate the degradation processes of acrylic and styrene-acrylic paints after exposure to ozone (O₃) and RH. A first comparison of FTIR and Py-GC/MS results allowed to obtain qualitative information on the degradation products and the influence of the pigments on the paints’ stability. The combination of these results represents a significant potential for the use of data fusion methods. Specifically, the datasets obtained by FTIR and Py-GC/MS were combined using a low-level data fusion approach and subsequently processed by principal component analysis (PCA). It allowed to evaluate the different chemical impact of the variables for the characterization of unaged and aged samples, understanding which paint is more prone to ozone degradation, and which aging variables most compromise their stability. The advantage of this method consists in simultaneously evaluating all the FTIR and Py-GC/MS variables and describing common degradation patterns. From these combined results, specific information was obtained for further suitable conservation practices for modern and contemporary painted films.

PMID:35566956 | DOI:10.3390/polym14091787

Polymers (Basel). 2022 Apr 27;14(9):1793. doi: 10.3390/polym14091793.

ABSTRACT

This work evaluated the fracture toughness of the low-temperature carbonized elastomer-based composites filled with shungite and short carbon fibers. The effects of the carbonization temperature and filler content on the critical stress intensity factor (K_1c) were examined. The K_1c parameter was obtained using three-point bending tests for specimens with different l/b ratio (notch depth to sample thickness) ranging from 0.2 to 0.4. Reliable detection of the initiation and propagation of cracks was achieved using an acoustic sensor was attached to the samples during the bending test. The critical stress intensity factor was found to decrease linearly with increasing carbonization temperature. As the temperature increased from 280 to 380 °C, the K_1c parameter was drastically reduced from about 5 to 1 MPa·m^1/2 and was associated with intense outgassing during the carbonization step that resulted in sample porosity. The carbon fiber addition led to some incremental toughening; however, it reduced the statistical dispersion of the K_1c values.

PMID:35566962 | DOI:10.3390/polym14091793

Polymers (Basel). 2022 Apr 27;14(9):1778. doi: 10.3390/polym14091778.

ABSTRACT

The aim of this in vitro study was to evaluate the effects of substrate and cement shades on the translucency and color of lithium-disilicate and zirconia CAD/CAM materials. Two light-cured resin cements (RelyX Veneer Cement; 3M; Choice 2 Veneer Cement; Bisco Dental) with a standardized thickness (0.1 mm) were tested in combination with two different monolithic CAD/CAM materials (E-Max CAD (LI₂SI₂O₅); Ivoclar Vivadent; Katana (ZrO₂); Kuraray-Noritake Dental) on two different colored composite substrates used as a dentin (Filtek Supreme XTE; 3M); for a total of 12 combinations (n = 10). The specimens’ color was measured with a spectrophotometer (Spectroshade; MHT). Measurements were taken using the CIELAB color coordinate system (L*a*b*) against black and white backgrounds. L*a*b* values were statistically analyzed for the variables Substrate, Ceramic, and Cement by applying a Three-Way ANOVA followed by the Tukey Test for post-hoc comparison (p < 0.05). Translucency Parameter (TP) and Constant Ratio (CR) were assessed to evaluate translucency; acceptability and perceptibility thresholds (ΔE₀₀ 1.8 and 0.8) were used. Statistically significant influence was found for factors ceramic material, cement shade, and substrate color (p < 0.05). Unacceptable color differences were reported for Li₂Si₂O₅. Opacity was significantly higher when white opaque cement shade was employed. Ceramic type and cement shade significantly influenced L*a*b* color coordinates. The final translucency and color of ceramic restorations can, therefore, be influenced by ceramic material, cement shade, and substrate color.

PMID:35566944 | DOI:10.3390/polym14091778

Polymers (Basel). 2022 Apr 26;14(9):1749. doi: 10.3390/polym14091749.

ABSTRACT

(1) Introduction: Denture adhesives (DAs) promote stability, chewing ability, and quality of life. The objective of this study was to compare the effectiveness of original brand DAs and white brands in their retention of conventional complete dentures. (2) Methods: This study followed the recommendations of the international standard ISO 10873. Three original brands of DA (Corega^® Fixação 3D, GlaxoSmithKline^®, Stafford Miller Ltd., Dungarvan Co. Waterford, Ireland), KuKident^® Pro Procter & Gamble Technical Centres^®, Ltd., Whitehal Lane, Germany and Elgydium^® Fix, Laboratórios URGO^® SL, Florida, Spain) were compared to three white brands (Fixação Extra Forte Pingo Doce^®, Laboratórios Cosmodent^®, Cantabria, Spain), Fixador de Próteses (Continente^®, Propack^®,Gmbh, Ladenburg, Germany) and Creme Fixador de Próteses (Auchan^®, Ellipse^®, Roubaix, France). Their retention capacities were analyzed using a mechanical test device. (3) Results: The mean retentive ability of original brand adhesives (M = 11.16, SD = 5.27) was significantly higher (t(298) = 11.88; p < 0.001) than that of the white brands (M = 5.92, SD = 1.18). When comparing all brands, statistically significant differences were also observed, F(5.294) = 707.68 (p < 0.001). The generic adhesive results were more homogeneous. The generic brands from Continente^® (M = 5.24, SD = 0.94) and Auchan^® (M = 5.80, SD = 0.79) were not significantly different, while the Pingo Doce^® brand obtained significantly higher mean retention results (M = 6.71, SD = 1.28). (4) Conclusions: The original brands of DA have a significantly higher retentive ability than the white brands. Elygidim^® Fix had the worst result of the three original brands, and the product from Pingo Doce^® had the best result among the three white brands.

PMID:35566919 | DOI:10.3390/polym14091749

Polymers (Basel). 2022 Apr 19;14(9):1648. doi: 10.3390/polym14091648.

ABSTRACT

Particleboards are used in the manufacturing of furniture and are often part of the interior of buildings. In the event of a fire, particleboards are a substantial part of the fuel in many building fires. The aim of the article is to monitor the effect of radiant heat on the surface of particle board according to the modified procedure ISO 5657: 1997. The significance of the influence of heat flux density and particle board properties on its thermal resistance (time to ignition) was monitored. Experimental samples were used particle board without surface treatment, with thicknesses of 12, 15, and 18 mm. The samples were exposed to a heat flux from 40 to 50 kW·m^-2. The experimental results are the initiation characteristics such as of the ignition temperature and the weight loss. The determined factors influencing the time to ignition and weight loss were the thickness and density of the plate material, the density of the radiant heat flux and the distance of the particle board from the radiant source (20, 40, and 60 mm). The obtained results show a significant dependence of the time to ignition on the thickness of the sample and on the heat flux density. The weight loss is significantly dependent on the thickness of the particle board. Monitoring the influence of time to ignition from sample distance confirmed a statistically significant dependence. As the distance of the sample from the source increased, the time to ignition decreased linearly. As the distance of the sample from the source increased, the time to ignition increased.

PMID:35566818 | DOI:10.3390/polym14091648

Polymers (Basel). 2022 Apr 22;14(9):1715. doi: 10.3390/polym14091715.

ABSTRACT

Currently, the provisional stenting technique is the gold standard in revascularization of lesions located in the left main (LM) bifurcation. The benefit of the routine kissing balloon technique (KBI) in bifurcation lesions is still debated, particularly following the single stent treatment. We compared the latest-generation drug-eluting stent (DES) with no side branch (SB) dilatation “keep it open” technique (KIO) vs. KBI technique vs. bifurcation dedicated drug-eluting stent (BD-DES) implantation. In vitro testing was performed under a static condition in bifurcation silicone vessel models. All the devices were implanted in accordance with the manufacturers’ recommendations. As a result, computational fluid dynamics (CFD) analysis demonstrated a statistically higher area of high shear rate in the KIO group when compared to KBI. Likewise, the maximal shear rate was higher in number in the KIO group. Floating strut count based on the OCT imaging was significantly higher in KIO than in KBI and BD-DES. Furthermore, according to OTC analysis, the thrombus area was numerically higher in both KIO and KBI than in the BD-DES. Scanning electron microscopy (SEM) analysis shows the highest degree of strut coating damage in the KBI group. This model demonstrated significant differences in CFD analysis at SB ostia with and without KBI optimization in the LM setting. The adoption of KBI was related to a meaningful reduction of flow disturbances in conventional DES and achieved results similar to BD-DES.

PMID:35566886 | DOI:10.3390/polym14091715

J Clin Med. 2022 May 9;11(9):2675. doi: 10.3390/jcm11092675.

ABSTRACT

Background: The present study aims to compare the accuracy of jaw repositioning in bimaxillary orthognathic surgery using digital surgical planning in cleft lip and palate patients and in non-syndromic skeletal class III patients in order to investigate if orthognathic surgery achieves different results in the first group of patients. Method: This study included 32 class III adult patients divided into 2 groups: cleft lip and palate (A, n = 16) and non-cleft (B, n = 16). For each patient, a 2D pre-surgical visual treatment objective was performed by the surgeon to predict hard tissue changes, and the surgical outcome was compared with that planned by using cephalometric measurement (ANB, SNA, SNB, Ar-Go-Me, S-Ar-Go). The statistical analysis showed equivalence between obtained and planned results for each measurement both in group A and in group B, but the difference between the planned and the obtained result was smaller in group B regarding ANB angle. Conclusions: Digital surgical planning ensures better predictability of the surgical results and higher accuracy of surgery in complex patients, such as those with cleft lip and palate.

PMID:35566801 | DOI:10.3390/jcm11092675

FASEB J. 2022 May;36 Suppl 1. doi: 10.1096/fasebj.2022.36.S1.L7857.

ABSTRACT

Many medical treatments have been proposed and utilized to mitigate the effects of oxidants on mammalian cells. Some studies have demonstrated the antioxidative effects of EGCG (an active ingredient in green tea) against cellular oxidants such as camptothecin (CAMPT). However, not many studies have shown how EGCG mitigates the effects of CAMPT on UMR cells. We hypothesized that EGCG mitigates the effects of CAMPT on cell proliferation and biophysical parameters in UMR cells by inhibiting CAMPT-induced apoptosis. Briefly, UMR cells were routinely passaged, counted, plated at 4.8 x 10⁵ cells/mL in six-well culture plates, then treated with varying concentrations of CAMPT. The cultures were incubated for 72 hours at 37°C + 5% CO₂ infusion. Cells were subsequently counted to establish the proliferation and viability of the induced cells as compared to controls. In another experiment, designated UMR cells were co-treated with CAMPT and different concentrations of EGCG then processed, as mentioned above, to evaluate whether or not the EGCG treatment was able to mitigate the oxidative effect of CAMPT through proliferation / viability studies. Apoptosis markers were assessed for each experiment by using a Caspase-3/CPP32 Colorimetric Assay Kit. Lastly, designated cells were treated with CAMPT alone, or CAMPT +EGCG then assessed using electric cell-substrate impedance sensing (ECIS) technology to explore the effects of the chemicals used on key biophysical parameters of UMR cells (i.e. cell membrane resistance, rate of cell spreading and cell attachment). Briefly, CAMPT-treated and CAMPT+EGCG-treated UMR cells were plated at 2.5 x 10⁵ cells/mL in eight-well ECIS array plates. The plates were placed into the ECIS array holder and incubated at 37°C with 5% CO₂. The biophysical parameters (cell membrane resistance/impedance, cell spreading, cell attachment) were monitored and measured in real-time for 48 hours, using the ECIS instrument. F test ANOVA was used to compare variances between all trials and all values in the results were expressed as means ±SD. The results of the proliferation study showed a decrease in CAMPT-treated UMR cell proliferation in a concentration-dependent manner (Figure 1). Cells co-treated with CAMPT + EGCG revealed that EGCG was able to reverse the oxidative effects of CAMPT on the UMR cells in a concentration-dependent manner *Figure 2). The Caspase-3/CPP32 Colorimetric Assay showed an increase in apoptotic marker activity from the CAMPT-induced samples in contrast with the uninduced controls. The ECIS technology documented decreases in biophysical parameters in the UMR cells when CAMPT alone was used. Co-treatment of the cells with CAMPT+EGCG showed a reverse effect on the biophysical parameters. F-Test ANOVA yielded statistically significant values with p values <0.05. The results of this research suggest that EGCG is effective in protecting UMR cells from oxidative stress by inhibiting apoptosis. Moreover, results from the ECIS instrument validates this technology as a corroborator of the biological effects of CAMPT and EGCG on UMR cells. This study suggests that EGCG has a protective role in mitigating oxidative stress in mammalian cells.

PMID:35557469 | DOI:10.1096/fasebj.2022.36.S1.L7857

FASEB J. 2022 May;36 Suppl 1. doi: 10.1096/fasebj.2022.36.S1.L7913.

ABSTRACT

Tissue resident macrophages play a major role in the regulation of the extracellular matrix (ECM). The ECM provides an essential scaffold and mechanical stability for blood vessels, but remodeling due to acute injury or chronic inflammatory conditions like hypertension promotes vascular stiffening. We have previously shown that pulse wave velocity (PWV), a measure of arterial stiffness, is higher in male and ovariectomized (OVX) female mice versus intact female mice. RNA-sequencing of aortas from intact and OVX mice revealed changes in several genes involved in fibrosis as well as macrophage function. Therefore, we hypothesized that estrogen protects from arterial stiffening through maintenance of “protective” macrophages and limiting pro-fibrotic ECM components. Based on the RNAseq results, we assessed the impact of estrogen on aortic expression of four fibrosis-associated genes: decorin (DCN), endothelin-1 (Edn1), type III collagen α1 (Col3a1), and connective tissue growth factor (CTGF) as well as four cell surface macrophage markers: colony stimulating factor 1 receptor (CSF1R), lymphatic vessel endothelial hyaluronan receptor 1 (LYVE1), AXL receptor tyrosine kinase (Axl), and growth arrest specific 6 (Gas6).

METHODS: Female C57BL/6 mice were ovariectomized (OVX) at 8 weeks or remained intact. PWV was obtained as a measure of arterial stiffness using a Vevo 1100 high resolution ultrasound. Mice were euthanized between 20-23 weeks of age for tissue collection. RNA was isolated from aortas using a Qiagen RNeasy Mini Kit and gene expression was quantified using droplet digital polymerase chain reaction (ddPCR). Statistical analysis was performed using an unpaired t-test.

RESULTS: Abdominal PWV was increased in OVX mice compared with intact mice (p<0.0001). Surprisingly, OVX induced a significant decrease (p=0.045) in DCN expression, while a downward trend was found for CTGF (p=0.10) and Col3a1 (p=0.08) but not Edn1 (p=0.59). OVX also decreased the expression of macrophage markers CSF1R (p=0.022) and LYVE1 (p=0.047), with a downward trend for Gas6 (p=0.096) but not Axl (0.161).

CONCLUSION: Increased PWV in OVX mice was not accompanied by upregulation of pro-fibrotic genes but was associated with decreases in macrophage markers CSF1R and LYVE1 in the aorta. Therefore, estrogen loss may promote vascular stiffening through changes in the amounts or functions of specific subsets of macrophages in the vasculature. Our data support previous studies establishing a relationship between CSF1R, LYVE1, and arterial homeostasis. Future studies will examine the impact of estrogen on aortic tissue resident macrophages using flow cytometry and the downstream signaling that promotes arterial stiffening.

PMID:35557457 | DOI:10.1096/fasebj.2022.36.S1.L7913