Disc Samples Research Articles

A novel approach for the lifetime prediction and structural health monitoring of concrete sewer systems exposed to biogenic sulphide corrosion

A novel, combined experimental-modelling approach is presented for the estimation of the corrosion depth, load bearing capacity and lifetime of unreinforced concrete sewer pipes exposed to prolonged biogenic sulphide corrosion. The biogenic sulphide corrosion process is mimicked through two types of representative chemical experiments, namely: (i) long-term experiments performed under moderately controlled pH conditions, where dry-cast concrete cube samples are exposed to monthly refreshed sulphuric acid solutions with initial pH values of 3, 2 and 1 for a period of 12 months, and (ii) short-term experiments carried out under highly controlled pH conditions, in which dry-cast concrete disk samples are subjected to sulphuric acid solutions with almost constant pH values of 2, 1 and 0.5 for a period of two months. By applying X-ray diffraction, optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy analyses, insight into the micro-scale morphology and elemental composition of the corrosion profile is obtained. In addition, the corrosion front and depth characteristics are measured by conducting phenolphthalein tests and analyses of surface colour and texture of macro-scale samples. From the experimental results, the time course of the corrosion depth is calibrated with a model for sulphate attack under a constant pH level. The model formulation is combined with detailed finite element method results from the literature to predict the long-term load bearing capacity of a concrete sewer pipe. The model is subsequently generalised for sulphate corrosion under a varying pH level. When combined with the installation of pH measuring devices on the inside of sewer pipes, the current engineering model may serve as an excellent practical tool for continuously monitoring the structural health and predicting the lifetime of in-situ sewer systems subject to sulphate attack under random acidity fluctuations.

Vertebral Endplate Defects Induced Mechanical Alterations and Disc Calcification.

Cross sectional comparative study. The current study aims to explore the calcification potential (BMP2 expression) of intervertebral discs and its association with the presence of vertebral endplate defects visible on MRI. Forty-seven herniated lumbar disc samples obtained from patients aged 20-76 (31M/16F) undergoing surgery. Five-µm thin sections were stained with H&E in order to assign a histological degeneration score (HDS) from 0-15 on the basis of cell density (0-5), structural alterations (0-4), granular changes (0-3) and mucus degeneration (0-3). Sections were immuno-stained with anti BMP-2 antibodies to observe the calcification potential in these discs. In addition, pre-operativeT2-T1 W MRI images of the lumbar spine were analyzed for the presence and type (typical or atypical) of vertebral endplate defects, grade of disc degeneration (Pfirrmann grade I-V), presence of high intensity zones (HIZ), and Modic changes at the operated level. Vertebral endplate defects, Modic changes & HIZ were observed in 81%, 29% and 21% of patients respectively. Mean HDS & BMP-2 expression was 9 ± 2 and mean 71 ± 36spots/mm2 respectively. Discs with adjacent vertebral endplate defects showed increased cell density (P = .004), mucus degeneration (P = .002), HDS (P = .01) and BMP-2 expression (P = .01). Discs with HIZ also had increased HDS, but significance was seen with increased BMP2 expression (P = .006). HDS showed a positive correlation with BMP 2 expression (r = .30, P = .04). These findings suggest that the altered mechanical environment of discs is strongly associated with BMP-2 expression which is an important marker of intervertebral disc calcification.

PRODIGE – planet-forming disks in Taurus with NOEMA

Context. The physics and chemistry of planet-forming disks are far from being fully understood. To make further progress, both broad line surveys and observations of individual tracers in a statistically significant number of disks are required. Aims. Our aim is to perform a line survey of eight planet-forming Class II disks in Taurus with the IRAM NOrthern Extended Millimeter Array (NOEMA), as a part of the MPG-IRAM Observatory Program PRODIGE (PROtostars and DIsks: Global Evolution; PIs: P. Caselli and Th. Henning). Methods. Compact and extended disks around T Tauri stars CI, CY, DG, DL, DM, DN, IQ Tau, and UZ Tau E are observed in ~80 lines from > 20 C-, O,- N-, and S-bearing species. The observations in four spectral settings at 210–280 GHz with a 1σ rms sensitivity of ~8–12 mJy beam−1 at a 0.9″ and 0.3 km s−1 resolution will be completed in 2024. The uv visibilities are fitted with the DiskFit model to obtain key stellar and disk properties. Results. In this first paper, the combined 12CO, 13CO, and C18O J = 2–1 data are presented. We find that the CO fluxes and disk masses inferred from dust continuum tentatively correlate with the CO emission sizes. We constrained dynamical stellar masses, geometries, temperatures, the CO column densities, and gas masses for each disk. The best-fit temperatures at 100 au are ~ 17–37 K, and decrease radially with the power-law exponent q ~ 0.05–0.76. The inferred CO column densities decrease radially with the power-law exponent p ~ 0.2–3.1. The gas masses estimated from 13CO (2–1) are ~0.001–0.2 M⊙. Conclusions. Using NOEMA, we confirm the presence of temperature gradients in our disk sample. The best-fit CO column densities point to severe CO freeze-out in these disks. The DL Tau disk is an outlier, and has either stronger CO depletion or lower gas mass than the rest of the sample. The CO isotopologue ratios are roughly consistent with the observed values in disks and the low-mass star-forming regions. The high 13CO/C18O ratio of ~23 in DM Tau could be indicative of strong selective photodissociation of C18O in this disk.

The SPHERE view of the Taurus star-forming region

The sample of planet-forming disks observed by high-contrast imaging campaigns over the last decade is mature enough to enable the demographical analysis of individual star-forming regions. We present the full census of Taurus sources with VLT/SPHERE polarimetric images available. The whole sample sums up to 43 targets (of which 31 have not been previously published) corresponding to one-fifth of the Class II population in Taurus and about half of such objects that are observable. A large fraction of the sample is apparently made up of isolated faint disks (equally divided between small and large self-shadowed disks). Ambient signal is visible in about one-third of the sample. This probes the interaction with the environment and with companions or the outflow activity of the system. The central portion of the Taurus region almost exclusively hosts faint disks, while the periphery also hosts bright disks interacting with their surroundings. The few bright disks are found around apparently older stars. The overall picture is that the Taurus region is in an early evolutionary stage of planet formation. Yet, some objects are discussed individually, as in an intermediate or exceptional stage of the disk evolution. This census provides a first benchmark for the comparison of the disk populations in different star forming regions.

OA29 Epigenetic regulation of IL-4 promoter targeting p300 attenuating intervertebral disc degeneration and pain by inhibiting IL-1β

Abstract Background/Aims Low back pain (LBP) is a prevalent condition primarily caused by intervertebral disc degeneration (IVDD), which imposes a substantial social and medical burden. Effective targeted treatments to prevent the progression of IVDD and alleviate LBP are still lacking. p300, a critical member of the histone acetyltransferase (HAT) family, is involved in the regulation of inflammation. This study aims to investigate the role of p300/IL-4 in IVDD and pain and elucidate the underlying molecular mechanism. Methods Human intervertebral disc samples were collected and graded based on the Pfirrmann grading scheme. A rat model of IVDD was established through posterior disc puncture, and various treatments were administered. Human nucleus pulposus cells (NPCs) were isolated and cultured, followed by assessments including qRT-PCR, Western blotting, immunofluorescence, and histopathological analyses. The mechanical and thermal hyperalgesia were assessed using von Frey hair tests and the plantar test, respectively. Chromatin immunoprecipitation (ChIP) and ChIP-qPCR were performed, and lentivirus transduction was used for p300 knockdown. Results We investigated the role of CREB binding protein (CBP)/p300 in IVDD. Degenerated nucleus pulposus (NP) tissues from IVDD patients exhibited a significant downregulation of p300 at both nucleic acid and protein levels, while CBP levels remained unchanged. Manipulating p300 expression in NPCs regulated matrix production, with p300 overexpression enhancing aggrecan and collagen II expression and knockdown leading to increased matrix-degrading proteins. In a rat IVDD model, activating p300 function with CTPB (p300-specific activator) alleviated IVDD and pain, while inhibiting p300 with C646 exacerbated IVDD and pain. Transcriptome analysis implicated IL-4 as a downstream effector of p300, and IL-4 demonstrated protective effects against IVDD and pain. Mechanistically, p300 was found to acetylate H3K27 at the IL-4 promoter, promoting its expression. Conclusion The novel findings of this study suggest that the p300/IL-4/IL-1β axis may represent a promising therapeutic target for IVDD and LBP. These results propose a hypothesis that, early in the inflammatory phase, NPCs may initiate a self-protective mechanism through p300, aiding itself in preserving a favourable metabolic microenvironment. This mechanism is primarily mediated by the expression of IL-4, which has the capacity to counteract IL-1β, rather than TNF-α. Disclosure H. Cui: None. Z. Zheng: None.

Denture base materials: An in vitro evaluation of the mechanical and color properties

ObjectivesThis study aimed to compare the physical and mechanical properties of four denture base materials: Polyan IC (PA), milled polymethylmethacrylate (PMMA), three-dimensional (3D)-printed resin (3DP), and SR Ivocap (SR). MethodsNinety-six samples were prepared and divided into four groups as follows. Group A consisted of 3DP (Asiga DentaBASE, Asiga) fabricated using a manufacturer-recommended 3D printer (Asiga Pro 4k, Asiga). Group B comprised milled PMMA (MP) (Ivotion Base, Ivoclar Vivadent). Group C included PA (BredentSenden), meanwhile, group D involved SR (Ivoclar VivadentSchaan). Cuboid samples (65 mm x 10 mm x 2.5 mm) were used for biaxial flexure strength testing in a universal testing machine (UTM). Cylindrical samples of 20 mm x 40 mm were used for compressive strength testing in a UTM. Additionally, cuboid samples (65 mm x 10 mm x 2.5 mm) were used for Vickers surface hardness testing in a microhardness tester. disk samples (10 mm x 2.5 mm) were employed for color stability testing both in a coffee solution and Coca-Cola, using a digital spectrophotometer. Statistical analyses were performed using one-way analysis of variance and Tukey's post hoc analysis (α=0.05). ResultsMP demonstrated superior compressive strength (p = 0.002) and color stability compared to that exhibited by 3DP (p < 0.001) while displaying similar flexure strength (p = 0.336) and hardness (p = 0.708). MP and PA displayed similar compressive strength (p = 0.081), flexure strength (p = 0.159), and color stability in coke (p = 0.071). However, MP had reduced hardness (p < 0.001) and color stability in coffee (p < 0.001). Moreover, MP demonstrated a higher compressive strength (p < 0.001) than that displayed by SR. However, the flexure strength, hardness, and color stability were similar (p > 0.05). Furthermore, 3DP exhibited comparable compressive strength (p = 0.334) to that of PA but demonstrated significantly lower flexure strength (p = 0.005), hardness (p < 0.001), and color stability (p < 0.001) compared to PA. In comparison to SR, PA had a higher compressive strength (p < 0.001), hardness (p = 0.001), and color stability in coffee (p < 0.001), although they demonstrated similar (p > 0.05) flexure strength and color stability in coke. ConclusionsThe MP and PA demonstrated superior compressive strength than that exhibited by the other materials tested. The tested materials had similar flexure strengths, except for PA which demonstrated superiority over the 3DP. Among all tested materials, PA exhibited the highest hardness, while the 3DP was the least color-stable. Clinical SignificanceConsidering the mechanical properties and color stability, Polyan and milled polymethylmethacrylate are preferred for complete denture fabrication. However, the limited repairability and complex handling of Polyan should be considered.

Experimental and numerical study on the dynamic mode III fracture behaviors of rock using an axially notched flattened Brazilian disc in SHPB tests

The dynamic mode I and mode II fracture of rock have been widely investigated over the past decades. However, the lack of dynamic mode III fracture testing method and the rare understanding of mode III fracture mechanism of rock remain a significant knowledge gap in the realm of rock mechanics. In this work, an innovative axially notched flattened Brazilian disc (ANFBD) sample is proposed for the mode III fracture tests of rocks using the split Hopkinson pressure bar (SHPB). Firstly, the optimal geometrical dimension of the ANFBD sample for achieving true mode III fracture of rocks is comprehensively discussed using finite element method (FEM) analysis. Then, the reliability of ANFBD-SHPB method is experimentally verified through dynamic mode III fracture experiments on the Fangshan marble (FM). Laboratory experimental results show that the mode III fracture toughness (KIIId) values of FM are approximately 2.8 times of the mode I fracture toughness (KId) values at similar dynamic loading rates. Post-mortem examinations on the fracture surfaces show that the famous facet coarsening mechanism in mode III fracture is suppressed under high loading rates. Furthermore, insightful assessments regarding the inner progressive fracturing behaviors of the ANFBD sample are given by virtue of three-dimensional discrete element method (DEM) simulation. Moment tensor (MT) analysis indicates that the shear fracture mechanism mainly dominates the whole failure process of the ANFBD sample, while the tensile fracture mechanism slightly increases during the facet coarsening process. These results are of significant importance for revealing the failure mechanism of rock under dynamic mode III loading and give some beneficial implications for natural strike-slip fault structures.

Fracture response of thermal-treated granite under mode III loading: Through the edge-notched diametrically compressed disk specimen

The deep rock mass is subject to a high degree of coupling of geothermal and complex loading, and complex mechanical and hydraulic loading induces out-of-plane progression of primary fractures, culminating in the formation of pure mode III fractures. To study the impact of high temperatures on the fracture behavior of pure mode III, the edge-notched diametrically compressed (ENDC) granite discs were heat treated at different temperatures (25, 200, 400, 500, and 600 °C). Subsequently, comparative tests were conducted on both pure mode III and pure mode I fracture, using the digital image correlation (DIC) method and the acoustic emission (AE) technique. The results demonstrate that as the temperature increases, the mass and P-wave velocity decrease. Furthermore, under pure mode III loading, the ENDC sample exhibits higher peak loads and fracture toughness (KIIIc) compared to mode I (KIc), which shows a decrease of 60.72 % in KIIIc and 73.75 % in KIc after thermal treatment at 600 °C compared to the ambient conditions. Simultaneously, the elevated temperature augmentes the cumulative AE counts during loading. The variations in horizontal displacement elevation deviation (HDED) on either side of the deformation concentration zone indicate that the samples are more resistant to crack extension under pure mode III loading. In addition, a positive linear correlation is noted between KIIIc and KIc of ENDC disc samples. The relationship between rebound values and fracture toughness of ENDC discs was discussed, and discovered that the KIIIc and KIc values are quadratic with the rebound values tested by the complete disc. The discussed results may serve as an initial prediction of fracture toughness values.

Activation of Nuclear Factor Erythroid 2-Related Factor 2 Antagonizes the Reactive Oxygen Species Modulator 1-Induced Oxidative Stress in Nucleus Pulposus Cells

This study investigates the role of Reactive Oxygen Species Modulator 1 (ROMO1) in oxidative stress within nucleus pulposus (NP) cells and its potential regulation by Nuclear factor erythroid 2-related factor 2 (Nrf2). Intervertebral disc samples from patients were collected, and ROMO1, Nrf2, collagen I/II levels were analyzed to establish their potential connection. Human NP cells were cultured and exposed to H2O2 to induce oxidative stress. To elucidate ROMO1’s impact on NP cell metabolism, NP cells were transfected with ROMO1. Concurrently, Nrf2 activators and inhibitors were used to modulate Nrf2 expression during culturing. Oxidative stress was assessed through CAT and SOD1 gene expression analysis and measurement of cellular reactive oxygen species (ROS) production. NP cell status was determined by evaluating cell viability and collagen I/II expression. Results indicated elevated ROMO1 expression in severe intervertebral disc degeneration (IDD) and after H2O2 treatment. ROMO1 overexpression increased ROS production, suppressed CAT, SOD, and collagen II expression, while elevating collagen I and negatively affecting cell viability. However, Nrf2 activation effectively suppressed ROMO1 expression and protected NP cells from oxidative stress induced by H2O2 or ROMO1. In conclusion, ROMO1 exacerbates oxidative stress and contributes to NP cell degeneration, a process mitigated by Nrf2 activation.

M giants with IGRINS

Context. To be able to investigate the chemical history of the entire Milky Way, it is imperative to also study its dust-obscured regions in detail, as this is where most of the mass lies. The Galactic Center is an example of such a region. Due to the intervening dust along the line of sight, near-infrared spectroscopic investigations are necessary to study this region of interest. Aims. The aim of this work is to demonstrate that M giants observed at high spectral resolution in the H- and K-bands (1.5–2.4 μm) can yield useful abundance ratio trends versus metallicity for 21 elements. These elements can then also be studied for heavily dust-obscured regions of the Galaxy, such as the Galactic Center. The abundance ratio trends will be important for further investigation of the Galactic chemical evolution in these regions. Methods. We observed near-infrared spectra of 50 M giants in the solar neighborhood at high signal-to-noise and at a high spectral resolution with the IGRINS spectrometer on the Gemini South telescope. The full H- and K-bands were recorded simultaneously at R = 45 000. Using a manual spectral synthesis method, we determined the fundamental stellar parameters for these stars and derived the stellar abundances for 21 atomic elements, namely, F, Mg, Si, S, Ca, Na, Al, K, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, Ce, Nd, and Yb. We systematically studied useful spectral lines of all these elements in the H- and K-bands. Results. We demonstrate that elements can be analyzed from H- and K-band high-resolution spectra, and we show which spectral lines can be used for an abundance analysis, identifying them line by line. We discuss the 21 abundance ratio trends and compare them with those determined from APOGEE and from the optical Giants in the Local Disk (GILD) sample. From high-resolution H- and K-band spectra, the trends of the heavy elements Cu, Zn, Y, Ce, Nd, and Yb can be retrieved. This opens up the nucleosynthetic channels, including the s-process and the r-process in dust-obscured populations. The [Mn/Fe] versus [Fe/H] trend is shown to be more or less flat at low metallicities, implying that existing non-local thermodynamic equilibrium correction is relevant. Conclusions. With high-resolution near-infrared spectra, it is possible to determine reliable abundance ratio trends versus metallicity for 21 elements, including elements formed in several different nucleosynthetic channels. It is also possible to determine the important neutron-capture elements, both s- and r-dominated elements. This opens up the possibility to study the chemical evolution in detail of dust-obscured regions of the Milky Way, such as the Galactic Center. The M giants are useful bright probes for these regions and for future studies of extra-galactic stellar populations. A careful analysis of high-quality spectra is needed to retrieve all of these elements, which are often from weak and blended lines. A spectral resolution of R ≳ 40 000 is a further quality that helps in deriving precise abundances for this range of elements. In comparison to APOGEE, we can readily obtain the abundances for Cu, Ce, Nd, and Yb from the H-band, demonstrating an advantage of analyzing high-resolution spectra.

Reducing fuel consumption of a light-duty vehicle by incorporating CuO nanoparticles in compressor lubricant of air-conditioning system

This experimental study aims to investigate the effects of copper (II) oxide (CuO) nanoparticles (~50 nm, 99.9% trace metal basis) incorporation in polyalkylene glycol (PAG) lubricant of a compressor included in air-conditioning (AC) system of a light duty passenger car. Observations on fuel consumption in real-world driving tests while the AC system is fully running were conducted. In order to determine the impacts of CuO nanoparticle incorporation in PAG oil, friction (pin-on-disc tribotester) and wear tests were carried out along with surface visualization analyses of scanning electron microscopy (SEM) and atomic force microscopy (AFM) on the disc samples laser-cut from the spare AC compressor vanes. Morphology and thermal stability of the CuO nanoparticles were also investigated via SEM and thermal gravimetric (TG) analyses, respectively. Wear rate (WR), average coefficient of friction (µa) and surface roughness analyses on the specimen surfaces were conducted to procure a comprehensive knowledge about the tribological improvement of CuO nanoparticles. All analyses were repeated on the identical metal samples in PAG lubricant bath (PL) and CuO nanolubricant (NL) separately under the same conditions and average of the test results were taken into account to minimize error. The results demonstrate that reductions of 15.5% in average coefficient of friction, 33% in wear rate and 9% in average surface roughness were achieved resulting in a decrease of 7.7% in fuel consumption at designated driving conditions.

Strain rate-dependent failure mechanics of the intervertebral disc under tension/compression and constitutive analysis

BackgroundThe intervertebral disc exhibits not only strain rate dependence (viscoelasticity), but also significant asymmetry under tensile and compressive loads, which is of great significance for understanding the mechanism of lumbar disc injury under physiological loads. ObjectiveIn this study, the strain rate sensitive and tension-compression asymmetry of the intervertebral disc were analyzed by experiments and constitutive equation. MethodThe Sheep intervertebral disc samples were divided into three groups, in order to test the strain rate sensitive mechanical behavior, and the internal displacement as well as pressure distribution. ResultsThe tensile stiffness is one order of magnitude smaller than the compression stiffness, and the logarithm of the elastic modulus is approximately linear with the logarithm of the strain rate, showing obvious tension-compression asymmetry and rate-related characteristics. In addition, the sensitivity to the strain rate is the same under these two loading conditions. The stress–strain curves of unloading and loading usually do not coincide, and form a Mullins effect hysteresis loop. The radial displacement distribution is opposite between the anterior and posterior region, which is consistent with the stress distribution. By introducing the damage factor into ZWT constitutive equation, the rate-dependent viscoelastic and weakening behavior of the intervertebral disc can be well described.

Species-specific prediction model of wood moisture content based on electromagnetic wave propagation time

Laboratory and field experiments were performed to examine the feasibility of using Time Domain Reflectometry (TDR) to monitor moisture content (MC) of wood and standing trees. The TDR was used to detect the electromagnetic wave propagation time of four tree species (Betula platyphylla, Tilia tuan, Picea asperata, and Fraxinus mandshurica) at different MCs. During the TDR test, effects of probe insertion depths on MC predictive accuracy were considered. The best results were obtained at an insertion depth of 8 cm. At the selective 8 cm insertion depth, a species-specific MC prediction model (0.94 ≤ R2 ≤ 0.98), a generalized model for the four species (R2 = 0.65), and a hybrid model for the species with similar densities (0.80 ≤ R2 ≤ 0.96) were constructed, respectively. Overall, the species-specific MC prediction model showed good predictive ability for both tree and wood disc samples, including that TDR can be used to detect wood and standing tree MC. If possible, the hybrid model can be used for species with similar density.

Energy harvesting using lead-free multilayer piezo stacks based on 0.95(Bi0.5Na0.5)TiO3-0.05(BaTiO3) piezoceramics through the addition of ZrO2

This paper explores the feasibility of utilizing lead-free multilayer piezo stacks, particularly focusing on Zr-doped 0.95(Bi0.5Na0.5)TiO3-0.05(BaTiO3) piezoceramics, for energy harvesting. Various lead-free BNT-BT disk samples with different Zr concentrations undergo structural, microstructural, and electrical characterizations. The results illustrate that Zr-doping improves piezoelectric constitutive parameters, notably at a 2.0 mol% concentration. Electromechanical tests were conducted on multilayer piezo stacks, involving variations in electric load, mechanical load, frequency, and number of stacked disks. These tests demonstrate the ability of the multilayer transducer to produce up to 1.5 V (peak) under particular conditions: a 250 Hz frequency, a 10 N mechanical load, and an open circuit electric load, utilizing a stack comprising 5 disks. Employing an analytical mathematical model, an effective d33eff of the system is determined, yielding values ranging from 588 to 625 pC/N for a stack composed of 5 disks. These findings highlight the considerable potential of lead-free multilayer piezo stacks in energy harvesting applications, offering crucial insights for the development of sustainable and eco-friendly energy solutions.

A new animal model of lumbar disc degeneration in rabbits

BACKGROUND CONTEXTThere are many models of lumbar disc degeneration, but mechanical stress-induced lumbar disc degeneration is rare. Here we propose a mechanical stress-induced lumbar disc degeneration model to better understand the molecular mechanism of lumbar disc degeneration under stress stimulation. PURPOSETo design a new model of lumbar disc degeneration under mechanical stress. STUDY DESIGNThe anatomic approach of the oblique lateral approach to lumbar fusion surgery was used to design a longitudinal compression device across the vertebral body of the rabbit to impose longitudinal load on the lumbar disc. METHODSNew Zealand white rabbits (n=30) were used. Screws were used to cross the rabbits’ lumbar vertebral bodies, and both sides of the screws were pressurized. Continuous compression was then performed for 28 days. Adjacent unpressurized lumbar discs serve as controls for pressurized lumbar discs. At 28 days after surgery, micro-computed tomography (CT) and magnetic resonance imaging (MRI) were performed on the rabbits’ lumbar discs. After the imaging examination, lumbar disc samples were removed, Safranin-O fast green and immunofluorescence was performed to detect the expression level of intervertebral disc degeneration-related proteins. RESULTSThe CT results showed that the disc height did not decrease significantly after mechanical loading. The MRI results showed that the signals in the pressurized disc decreased 28 days after loading. The results of Safranin-O fast green showed that the cartilage component of the intervertebral disc after mechanical compression was significantly reduced. The immunofluorescence results showed that the expression of ADAMTS5 and MMP13 protein in the nucleus pulposus of the intervertebral disc after mechanical compression increased, while the expression of SOX9 decreased, and the difference was statistically significant. Aggrecan's protein expression decreased, but was not statistically significant. CONCLUSIONSThis study designed a reliable model of disc degeneration in rabbits. It is more likely to mimic disc compression in the human body. CLINICAL SIGNIFICANCEThis animal model can be used as a basic model to study the molecular physiological mechanisms of discogenic low back pain.

Color measurements of the polarized light scattered by the dust in protoplanetary disks

Context. Many reflected light images of protoplanetary disks have been obtained with ground-based high-contrast instruments. Quantitative measurements of the reflected radiation provide strong constraints on the scattering dust which can clarify the dust particle evolution in these disks and the composition of the forming planets. Aims. We derived the wavelength dependence of the polarized reflectivity (Qˆφ/I*)λ or color for a sample of disks to contrain the dust based on these data. Further we searched for systematic differences in the dust properties between subgroups of disks. Methods. We selected from the ESO archive polarized imaging for 11 protoplanetary disks obtained at visible and near-infrared wavelengths with the SPHERE/ZIMPOL and SPHERE/IRDIS high contrast instruments. All disks have bright and well-resolved structures, such as rings or spirals, which allow accurate determinations of the intrinsic polarized reflectivity Qˆφ/I* at multiple wavelengths. For this, we corrected the observations for the smearing effects caused by the point spread functions (PSFs) of the individual dataset with a novel correction procedure applicable to inclined disks. For the 11 disks, we derived a total of 31 Qˆφ/I* values for wavelengths from 0.62 μm (R band) to 2.2 μm (Ks band) and compared our results, if possible, with previous determinations. For each disk, we derived a polarized reflectivity color ηV/IR between a visible band λ &lt; 1 μm and a near-IR band λ &gt; 1 μm and other wavelength combinations. We also consider model calculations for the polarized reflectivity colors η for protoplanetary disks to constrain the scattering properties of the dust. Results. The polarized reflectivities for the investigated disks structures are at a typical level between Qφ/I★ ~ 0.1% to 1.0%. These values depend strongly on the observing conditions and a correction for the PSF smearing effects is essential to obtain the intrinsic values Qˆφ/I*. Corrected values Qˆφ/I* are on average about a factor of 1.6 higher than the observed values. We checked the accuracy of the PSF calibrations procedure with simulations and literature data, and show that the large systematic errors in the observational values are reduced to a relative level ΔQˆφ/Qˆφ ≈ 10% or even less. The high accuracy yields wavelength gradients for the polarized reflectivity (Qˆφ/I*)φ or colors η which are significantly different between different objects. We find in our sample for all disks around Herbig stars (HD 169142, HD 135344B, HD 100453, MWC 758, and HD 142527) a red color ηv/IR &gt; 0.5, while four out of six disks around T Tauri stars (PDS 70, TW Hya, RX J1615, and PDS 66) are gray −0.5 &lt; ηV/IR &lt; 0.5. The red colors support the presence of rather compact dust grains, while the absence of blue colors (except for the near-infrared color of PDS 66) is not compatible with very porous aggregates composed of small monomers. We suspect, that the very red colors ηV/IR ≈ 2 obtained for LkCa 15 and MWC 758 could be the result of an "extra" reddening of the radiation illuminating the disk caused by absorbing hot dust near the star. We discuss the prospects of further improvements for the derivation of dust properties in these disks if the fractional polarization 〈pψ〉 or other parameters of the reflected light are also taken into account in future studies.

Improving the performance of bentonite-free water-based mud with lignin-based biopolymer

Various drilling problems are associated with bentonite utilization in water-based muds, including formation damage, reduced production rate and overall cost. Various alternative solutions in terms of bio and synthethic based polymers have been tested to replace bentonite. However, due to their higher costs and availability, industry is looking for ecofriendly alternatives to overcome this issue. This work aims to utilize a lignin-based polymer (BioDrill FM400) for the formulation of bentonite-free mud blends with various dosages. The rheological and filtration properties were examined using the API standard procedures both at standard and high-temperature conditions. Seven mud blends with various dosages of the additive (0-12 ppb) were prepared, and mud’s plastic viscosity, yield point and gel strength were measured using viscometer. Similarly, mud filtration characteristics were assessed both with API and HPHT filterpress. Three types of rock disks (0.25" thick x 2.5" in diameter) were utilized to mimic the actual pore plugging mechanism. The rheological findings showed that the PV, YP and GS were significantly improved. On the other hand, the filtrate volume and filtercake thickness were reduced by 63 and 42% for the Bandera Brown disk sample. The current formulation is useful in drilling the payzone section of the wellbore.

Evaluation of Less Invasive Sampling Tools for the Diagnosis of Cutaneous Leishmaniasis.

Diagnosis of cutaneous leishmaniasis (CL) usually relies on invasive samples, but it is unclear whether more patient-friendly tools are good alternatives for diverse lesions when used with polymerase chain reaction (PCR). Patients with suspected CL were enrolled consecutively in a prospective diagnostic accuracy study. We compared dental broach, tape disc, and microbiopsy samples with PCR as index tests, using PCR with skin slit samples as reference test. Subsequently, we constructed a composite reference test including microscopy, the 3 index tests and skin slit PCR, and we compared these same tests with the composite reference test. We assessed diagnostic accuracy parameters with 95% confidence intervals for all comparisons. Among 344 included patients, 282 (82.0%) had CL diagnosed, and 62 (18.0%) CL absence, by skin slit PCR. The sensitivity and specificity by PCR were 89.0% (95% confidence interval, 84.8%-92.1%) and 58.1% (45.7%-69.5%), respectively, for dental broach, 96.1% (93.2%-97.8%) and 27.4% (17.9%-39.6%) for tape disc, and 74.8% (66.3%-81.7%) and 72.7% (51.8%-86.8%) for microbiopsy. Several reference test-negative patients were consistently positive with the index tests. Using the composite reference test, dental broach, and skin slit had similar diagnostic performance. Dental broach seems a less invasive but similarly accurate alternative to skin slit for diagnosing CL when using PCR. Tape discs lack specificity and seem unsuitable for CL diagnosis without cutoff. Reference tests for CL are problematic, since using a single reference test is likely to miss true cases, while composite reference tests are often biased and impractical as they require multiple tests.

Evaluation of the amount of residual monomer released from different flowable composite resins

Today, resin materials are used in the restoration of permanent and deciduous teeth or as fissure sealants. The materials can contain different types of monomers (Bis-GMA, UDMA, TEGDMA). These monomers can be released into the oral cavity after polymerization. Residual monomers released from resin-containing restorative materials after polymerization have been reported to have negative effects on mechanical properties. The aim of our study is to evaluate the amount of residual monomers released after polymerization of different flowable composite resin materials using two different modes of LED light source. Composite disc samples (8 mm diameter/2 mm depth) prepared for each material group were polymerized using two different modes of the LED light device (Standard mode and extra power mode). HPLC (High Performance Liquid Chromatography) device was used to measure the amount of residual monomer release at 1 h, 1 day, 3 days and 7 days periods. Pairwise comparison of the differences between the materials was performed by Post-hoc test. For each residual monomer, the Kruskal Wallis test was used to analyze the difference between the materials in standard mode and the difference between the materials in extra power mode. According to the results of the study; Grandio flow flowable composite showed the highest release of TEGDMA and Bis-GMA while SDR® Flow flowable composite showed the lowest release of TEGDMA, Bis-GMA and UDMA. For all materials, the extra power mode resulted in more residual monomer release. TEGDMA and Bis-GMA release was detected in all tested flowable composites at all time periods.

Effectiveness of mechanical and chemical decontamination methods for the treatment of dental implant surfaces affected by peri-implantitis: A systematic review and meta-analysis.

To assess which decontamination method(s) used for the debridement of titanium surfaces (disks and dental implants) contaminated with bacterial, most efficiently eliminate bacterial biofilms. A systematic search was conducted in four electronic databases between January 1, 2010and October 31, 2022. The search strategy followed the PICOS format and included only in vitro studies completed on either dental implant or titanium disk samples. The assessed outcome variable consisted of the most effective method(s)-chemical or mechanical- removing bacterial biofilm from titanium surfaces. A meta-analysis was conducted, and data was summarized through single- and multi-level random effects model (p < .05). The initial search resulted in 5260 articles after the removal of duplicates. After assessment by title, abstract, and full-text review, a total of 13 articles met the inclusion criteria for this review. Different decontamination methods were assessed, including both mechanical and chemical, with the most common method across studies being chlorhexidine (CHX). Significant heterogeneity was noted across the included studies. The meta-analyses only identified a significant difference in biofilm reduction when CHX treatment was compared against PBS. The remaining comparisons did not identify significant differences between the various decontamination methods. The present results do not demonstrate that one method of decontamination is superior in eliminating bacterial biofilm from titanium disk and implant surfaces.