Altered Surface Research Articles

The Autogenous Coelenterate-Endocervical Polyp Uterine Cervix

Endocervical polyp represents as a benign, exophytic lesion constituted of variable admixture of proliferating endocervical glandular epithelium and metaplastic squamous epithelium permeated with a fibro-vascular core. The commonly encountered endocervical polyp is frequently accompanied by chronic inflammation, erosion of superficial epithelial surface and reactive alterations of layering epithelium.

Native Pig Neutrophil Products: Insights into Their Antimicrobial Activity.

Cationic antimicrobial peptides are molecules with potential applications for treating infections due to their antimicrobial and immunomodulatory properties. The aim of this work was to explore the antimicrobial activity and mechanisms of action of a porcine neutrophil cathelicidin mixture (MPPN). Gram-positive and Gram-negative bacteria were used to determine the minimum inhibitory concentration (MIC) and experiments of both time-kill kinetics and effects on growth curves were performed. Planar black lipid bilayer conductance was measured to analyze the interaction of MPPN with lipid bilayers. Visualization of bacterial surfaces and membrane alterations was achieved using atomic force microscopy and transmission electron microscopy. The effects on the activity of efflux pumps (EPs) were studied with an intracellular accumulation of acridine orange (AO) assay. In E. coli, MPPN behaves as a bactericide at high concentrations and as a bacteriostatic at lower concentrations. The bacteriostatic effect was also observed for slightly shorter periods in S. enterica. The mixture was not active on S. aureus. The increase in AO accumulation in the presence of MPPN indicates that, at least in E. coli, the mixture causes inhibition of the EP function. Observed and detected variable conductance events demonstrate a strong MPPN effect on lipid bilayers. Damage to the structure of treated E. coli indicates that MPPN induces alterations in the bacterial surface. The use of AMPs capable of inhibiting EP can be seen as a good tool to combat antimicrobial resistance since they could be used alone or in combination with other conventional antibiotics to which bacteria have become resistant.

The 18th amino acid glycine plays an essential role in maintaining the structural stabilities of γS-crystallin linking with congenital cataract

γS-crystallin is particularly rich in the embryonic nuclear region and is crucial to the maintenance of lens transparency and optical properties. Gene mutations in crystallin are the main factors leading to congenital hereditary cataracts, which are a major cause of visual impairment in children. Some mutations located in the 18th amino acid glycine of γS-crystallin were reported to be linking with congenital cataracts. However, the pathogenic mechanism has not been elucidated. Interestingly, we previously identified a novel variant of γS-crystallin (c.53G > A; p. G18D) with progressive cortical and sutural congenital cataracts in one Chinese family. In this study, we purified the γS-crystallin wildtype and mutant proteins to investigate the effects of the G18D mutation on the structural stability of γS-crystallin. The results showed that there were tertiary structural differences between the wild-type γS-crystallin and the G18D variant. The mutation significantly impaired the stability of γS-crystallin under environmental stress and promoted aggregation. Furthermore, molecular dynamics (MD) simulations showed that the mutation altered H-bonding and surface electrostatic potential. Significantly decreased stability along with an increased tendency to aggregate under environmental stress may be the major pathogenic factors for cataracts induced by the G18D mutation.

Influence of humidity in the alteration of unstable glasses

AbstractThe control of humidity between certain limits is essential to avoid the alteration of historical objects, such as unstable historical glasses. However, the usual limits can be altered due to the presence of volatile organic compounds. This work presents the results of the exposure of soda, potash, and mixed‐alkali silicate glasses to neutral and acidic (formic) atmospheres with ∼30%, ∼70%, and ∼100% relative humidity. The hygroscopic capacity of the glass was analyzed by gravimetry, and the surface alteration was evaluated by infrared spectroscopy, optical microscopy, and ion chromatography. In all glasses, the alteration begins with alkali ions’ lixiviation followed by the silica network's hydrolytic attack. The results showed that soda and mixed‐alkali silicate glasses exhibit similar behavior, while the potash‐lime one experienced the fastest degradation due to its composition. Results also confirmed that high humidity increased the alteration rate causing a higher hygroscopicity and reactivity of glasses. Finally, acidic environments promoted the ion‐exchange reaction at high humidity, accelerating the lixiviation of alkaline ions and promoting the diffusion of water into the glass network.

After the sun: a nanoscale comparison of the surface chemical composition of UV and soil weathered plastics

Once emitted into the environment, macro- (MaP), micro- (MP) and nanoplastics (NP) are exposed to environmental weathering. Yet, the effects of biogeochemical weathering factors occurring in the soil environment are unknown. As the transport, fate, and toxicity of MP and NP depend directly on their surface properties, it is crucial to characterize their transformation in soils to better predict their impact and interactions in this environment. Here, we used scanning transmission x-ray micro spectroscopy to characterize depth profiles of the surface alteration of environmental plastic debris retrieved from soil samples. Controlled weathering experiments in soil and with UV radiation were also performed to investigate the individual effect of these weathering factors on polymer surface alteration. The results revealed a weathered surface on a depth varying between 1 µm and 100 nm in PS, PET and PP environmental plastic fragments naturally weathered in soil. Moreover, the initial step of surface fragmentation was observed on a PS fragment, providing an insight on the factors and processes leading to the release of MP and NP in soils. The comparison of environmental, soil incubated (for 1 year) and UV weathered samples showed that the treatments led to different surface chemical modifications. While the environmental samples showed evidence of alteration involving oxidation processes, the UV weathered samples did not reveal oxidation signs at the surface but only decrease in peak intensities (indicating decrease of the number of chemical C bonds). After a one-year incubation of samples in soil no clear aging effects were observed, indicating that the aging of polymers can be slow in soils.

Laser-assisted plasma formation and ablation of Cu in a controlled environment

In this paper, we explore the surface and mechanical alterations of Cu, as well as the parameters of laser-assisted plasma and ablation. The irradiation source is a Nd: YAG laser with a constant irradiance of 1.0 GW/cm2 (1064 nm, 55 mJ, 10 ns, 10 Hz). Physical parameters such as electron temperature (Te) and electron number density (ne), sputtering yield (yield), ablation depth (depth), surface morphology (morphology), and hardness (Vickers) of laser irradiated Cu are evaluated using instruments such as a Laser Induced Breakdown Spectrometer (LIBS), Quartz Crystal Microbalance (QCM), Optical Emission Microscope (OEM), Scanning Electron Microscope (SEM), and Vicker's hardness tester. These physical characteristics have been studied in relation to changes in pressure (from 10 torr to 100 torr) and the composition of two inert ambient gases (Argon and Neon). Pressures of Ar and Ne are found to enhance the emission intensities of spectral lines of Cu, Te, and ne, as well as the sputtering yield, crater depth, and hardness of laser ablated Cu, to a maximum at 60 torr, after which they decrease with subsequent increases in pressure up to 100 torr. Increases in pressure up to 60 torr are connected with plasma confinement effects and increased collisional frequency, whereas decreases in pressure between 60 and 100 torr are ascribed to shielding effects by the plasma plume. All numbers are also found to be greater in Ar compared to Ne. In Ar, laser-ablated Cu reaches a maximum of 15218 K, 1.83 × 1018 cm−3, 8.59 × 1015 atoms/pulse, 231 m, and 147 HV, whereas in Ne, it reaches a maximum of 12000 K, 1.75 × 1018 cm−3, 7.70 × 1015 atoms/pulse, 200 m, and 116 HV. Ar is more likely than Ne to develop surface features such as craters, distinct melting pools with elevating edges, flakes, cones, etc. It is also shown that there is a significant association between the outcomes, with an increase in Te and ne being responsible for a rise in sputtering yield, ablation depth, surface morphology, and surface hardness. These findings have potential uses in plasma spectroscopy for materials science and in industrial applications of Cu.

Characterizing basalt-atmosphere interactions on Venus: A review of thermodynamic and experimental results

Abstract The surface of Venus is in contact with a hot (~470 °C), high pressure (92 bars), and caustic (CO2 with S, but little H2O) atmosphere, which should cause progressive alteration of the crust in the form of sulfate and iron-oxide coatings; however, the exact rate of alteration and mineral species are not well constrained. Different experimental approaches, each with its own limitations, are currently being used to constrain mineralogy and alteration rates. One note is that no experimental approach has been able to fully replicate the necessary conditions and sustain them for a significant length of time. Furthermore, geochemical modeling studies can also constrain surface alteration mineralogy, again with different assumptions and limitations. Here, we review recent geochemical modeling and experimental studies to constrain the state of the art for alteration mineralogy, rate of alteration, open questions about the surface mineralogy of Venus, and what can be constrained before the fleet of missions arrives later this decade. Combining the new results confirms that basalt on the surface of Venus should react quickly and form coatings of sulfates and iron-oxides; however, the mineralogy and rate of alteration are dependent on physical properties of the protolith (including bulk composition, mineralogy, and crystallinity), as well as atmospheric composition, and surface temperature. Importantly, the geochemical modeling results show that the mineralogy is largely controlled by atmospheric oxygen fugacity, which is not well constrained for the near-surface environment on Venus. Therefore, alteration experiments run over a range of oxygen and sulfur fugacities are needed across a wide range of Venus analog materials with varying mineralogy and crystallinity.

Strategies for Targeted Delivery via Structurally Variant Polymeric Nanocarriers

AbstractThe last decade has seen a meteoric rise in studies investigating polymeric aggregates as nanocarriers. When it comes to morphology, size, functionality, and immunostability, polymeric nanocarriers (PNCs) are unparalleled. With characteristics such as large surface area to volume ratio, amphiphilic nano‐environment, non‐toxic components, chemically modifiable composition, external surface alteration potential, uniform particle size, and stimuli‐dependent self‐assembly, PNCs have emerged as strong candidates for therapeutic applications. The article reviews the latest research on different challenges and strategies for targeted drug delivery and shall serve as guide to the researchers in designing site‐specific nanocarriers for application in future. The review systematically discusses the fundamental structural variation of the nanocarriers with emphasis on the influence of chemical alterations and the resulting effects on functionality; addresses the difficulties encountered with modes of administration; target selectivity and stimulus response.

Atlantic Multidecadal Variability modulates the climate impacts of El Niño–Southern Oscillation in Australia

Atlantic Multidecadal Variability (AMV) modulates El Niño–Southern Oscillation (ENSO) dynamics. Here, we explore the effect of warm (AMV+) and cold (AMV−) AMV conditions on the austral summer teleconnection of ENSO to Australia using idealized simulations performed with the NCAR-CESM1 model. AMV+ strengthens the mean and extreme precipitation and temperature responses to El Niño in south-western Australia and weakens the mean precipitation and temperature impacts in north-eastern Australia. The modulation of La Niña impacts by AMV is asymmetric to El Niño, with a weakening of the mean and extreme precipitation and temperature responses in eastern Australia. Decomposing the total difference in ENSO response between AMV phases, we find that the signals are mainly explained by the direct AMV modulation of ENSO and its teleconnections rather than by changes in background climate induced by AMV. The exception is ENSO-driven fire impacts, where there is a significant increase in burned area in south-eastern Australia only when El Niño and AMV+ co-occur. However, modulation of ENSO between AMV+ and AMV− does offset ∼37% of the decrease in burned area extent during La Niña summers. The altered surface climate response to ENSO in Australia by AMV is attributed to variations in large-scale atmospheric circulation. Under AMV+, there is increased subsidence over western Australia during El Niño associated with a westward shift of the local Walker circulation. A weakening of the upwelling branch of the local Hadley circulation over north-eastern Australia is responsible for the weakening of La Niña impacts in AMV+, accompanied by a strengthening of subsidence in south central Australia due to a weakening of the local Hadley circulation, amplifying La Niña impacts over this region. The results suggest the potential for AMV to drive multidecadal variability in ENSO impacts over Australia.

Facile bioactive transformation of magnesium alloy surfaces for surgical implant applications.

The market for orthopedic implant alloys has seen significant growth in recent years, and efforts to reduce the carbon footprint of medical treatment (i.e., green medicine) have prompted extensive research on biodegradable magnesium-based alloys. Magnesium alloys provide the mechanical strength and biocompatibility required of medical implants; however, they are highly prone to corrosion. In this study, Mg-9Li alloy was immersed in cell culture medium to simulate degradation in the human body, while monitoring the corresponding effects of the reaction products on cells. Variations in pH revealed the generation of hydroxyl groups, which led to cell death. At day-5 of the reaction, a coating of MgCO3 (H2O)3, HA, and α -TCP appeared on sample surfaces. The coating presented three-dimensional surface structures (at nanometer to submicron scales), anti-corrosion effects, and an altered surface micro-environment conducive to the adhesion of osteoblasts. This analysis based on bio-simulation immersion has important implications for the clinical use of Mg alloys to secure regenerated periodontal tissue.

Effect of Different Stabilizers on Spherical Agglomerates of Montelukast Sodium by Quasi Emulsion Solvent Diffusion (QESD)

Abstract: The present study was focused on the spherical crystallization of an asthmatic drug, Montelukast Sodium (MLS) using quasi emulsion solvent diffusion (QESD) technique in which distilled water was an external phase and the internal phase consisted of Ethanol which acts as good solvent and Ethyl acetate as a bridging liquid for recrystallization and agglomeration process. Apart from being poorly water soluble, MLS exhibits poor flow and compressibility. The spherical agglomeration was carried out in the presence of different stabilizers like acacia, PEG 4000, sodium lauryl sulphate, span 40 and tween 80. The prepared agglomerates were characterized in terms of production yield, drug content, solubility, in-vitro release profile, Xray diffraction (XRD), and Fourier transform infra red spectroscopy (FT-IR).The optimized spherical agglomerates exhibited excellent physicochemical and micromeritic properties, solubility and dissolution rate when compared with pure drug .The XRD also revealed a characteristic decrease in crystallinity. The dissolution studies demonstrated a marked increase in the dissolution rate. FTIR study reveals there are no chemical changes in prepared recrystallized agglomerates. The considerable improvement in the dissolution rate of MLS from optimized crystal formulation was attributed to the wetting effect of polymers, decreased drug crystallinity, altered surface morphology and micronization. If this process can be scaled-up to manufacturing level, this technology has the potential to provide the directly compressed spherical agglomerates with improving the physicochemical and micromeritic properties

Analysing criteria of formation in multi-stratified karst deposits: the observation of surfaces in Late Pleistocene faunal bones from Mora Cavorso cave (Latium, Central Italy)

ABSTRACT Mora Cavorso cave is mostly known for preserving one of the largest human burials of early Neolithic in Central Italy, but it holds archaeological and palaeontological finds ranging from Late Pleistocene to historical times. The observation of faunal bone surfaces from Late Pleistocene layers has been carried out mainly to verify the human contribution to the formation of the bone accumulations. The assemblages are made up of about 3750 finds, 48% of which taxonomically identified, while 31% of the total show traces of surface alterations. Layer 8, the deeper and partially excavated, shows few traces on 28 finds with a dark patina. For Layer 7, boluses by birds of prey, traces of digestion and gnawing by small carnivores show the main agents of the formation of the bone accumulation. For Layer 6, just a small percentage of finds shows traces referrable mostly to small carnivores, with a few traces referrable to rodents. For Layer 5, gnawing of small carnivores was observed, however the occurrence of burnt bones and cut traces confirmed the hypothesis, based on the discovery of lithic artefacts, that the oldest human attendance in the cave is here attested and dates to Epigravettian period.

Effects of extreme melt events on ice flow and sea level rise of the Greenland Ice Sheet

Abstract. Over the past decade, Greenland has experienced several extreme melt events, the most pronounced ones in the years 2010, 2012 and 2019. With progressing climate change, such extreme melt events can be expected to occur more frequently and potentially become more severe and persistent. So far, however, projections of ice loss and sea level change from Greenland typically rely on scenarios which only take gradual changes in the climate into account. Using the Parallel Ice Sheet Model (PISM), we investigate the effect of extreme melt events on the overall mass balance of the Greenland Ice Sheet and the changes in ice flow, invoked by the altered surface topography. As a first constraint, this study estimates the overall effect of extreme melt events on the cumulative mass loss of the Greenland Ice Sheet. We find that the sea level contribution from Greenland might increase by 2 to 45 cm (0.2 % to 14 %) by the year 2300 if extreme events occur more frequently in the future under a Representative Concentration Pathway 8.5 (RCP8.5) scenario, and the ice sheet area might be reduced by an additional 6000 to 26 000 km2 by 2300 in comparison to future warming scenarios without extremes. In conclusion, projecting the future sea level contribution from the Greenland Ice Sheet requires consideration of the changes in both the frequency and intensity of extreme events. It is crucial to individually address these extremes at a monthly resolution as temperature forcing with the same excess temperature but evenly distributed over longer timescales (e.g., seasonal) leads to less sea level rise than for the simulations of the resolved extremes. Extremes lead to additional mass loss and thinning. This, in turn, reduces the driving stress and surface velocities, ultimately dampening the ice loss attributed to ice flow and discharge. Overall, we find that the surface elevation feedback largely amplifies melting for scenarios with and without extremes, with additional mass loss attributed to this feedback having the greatest impact on projected sea level.

An advanced analytical approach to assess the long-term degradation of microplastics in the marine environment

Determining the hazards posed by microplastics (MPs, <5 mm) requires an understanding of plastic degradation processes when exposed to environmental weathering forces. However, despite their perceived risks, limited information exists on the natural weathering progression of microplastics in marine environments. Our findings from environmentally realistic conditions reveal that long-term marine weathering resulted in significant degradation of plastic surfaces and bulk-phases, which varied by time and plastic polymer type. Plastics displayed biofouling, and an altered surface morphology, thermal stability and chemical signature. Secondary micronanoplastics (MNPs, <1 µm) were formed from weathered plastic surfaces, supported by a significant reduction in the size of PCL and PVC pellets. Using real world data, we reveal that plastic surfaces can degrade at a rate of up to 469.73 µm per year, 12 times greater than previous estimates. Our time-series data contributes valuable information towards developing plastic specific risk assessment frameworks and future plastics policy.

Experimental investigation of wettability alteration of oil-wet carbonate surfaces using engineered polymer solutions: The effect of potential determining ions ([Mg2+/ SO42−], and [Ca2+/ SO42−] ratios)

Engineered water polymer flooding (EWPF) is a promising method to improve oil recovery in carbonate reservoirs holding more than half of the world's oil reserves. It involves combining engineered water (EW) and polymer flooding (PF) to modify rock wettability, reduce mobility ratio, promote polymer stability, and lower required polymer concentration. However, limited studies addressed the simultaneous effect of engineered water compositions (i.e. potential determining ions (PDIs)) on the viscosity of polymer and wettability alteration of various carbonate surfaces. Accordingly, this study aimed to investigate the effect of salinity, PDIs, and polymer functional groups (partially hydrolyzed polyacrylamide (HPAM), and acrylamide tertiary butyl sulfonic acid (ATBs)) on the wetting properties of calcite, chalk, and dolomite surfaces as well as the viscosity of solutions at static conditions. The experimental protocol included viscosity, contact angle (CA), pH, and static adsorption tests. Two combinations of PDIs were considered in the study: [Mg2+/SO42−], and [Ca2+/SO42−]. The results revealed that the polymer becomes more tolerant to the salinity as the sulfonation degree increases, given the same molecular weight. However, at a polymer concentration of 5000 ppm, the HPAM polymer showed higher viscosity than the ATBs-based polymers, as the formation brine (FB) was diluted to 100 folds (100DFB). The tendency of shifting the wettability of carbonate surfaces towards a more water-wet state using EW and EWP treatment solutions decreased in the following order: Chalk ≥ Calcite˃ Dolomite. The study also indicates that, the wettability alteration towards favorable condition is dependent on the initial wettability of the carbonate surface. The higher level of oil-wetness detected in aged dolomite, compared with calcite and chalk, resulted in less effectiveness of EWP for dolomites. However, the low polymer interaction with dolomite surfaces indicates a positive impact on reducing polymer consumption. Moreover, the HPAM polymer was more effective in altering the wettability of dolomite towards a water-wet state compared to the ATBs-based polymer. The overall results indicate that ATBs-based polymer is a potential candidate for optimizing the effectiveness of EWPF in carbonates.

Mineralogy and trace element geochemistry of hydrothermal sulfides from the Ari vent field, Central Indian Ridge

The Ari vent field (AVF) is an ultramafic-hosted seafloor massive sulfide (SMS) deposit in the middle part of the Central Indian Ridge. In this paper, we describe the detailed mineralogy and geochemistry of hydrothermal sulfide samples from the AVF, which can be classified into Fe–Cu- and Cu-rich types based on the major sulfide minerals. Sulfide mineralisation of the former type comprises: (1) stage I, early deposition of magnetite, pyrrhotite, isocubanite, chalcopyrite, and subhedral–euhedral pyrite under high-temperature fluid conditions (> 335 °C); (2) stage II, deposition of colloform pyrite, sphalerite, galena, and electrum from low-temperature fluids (< 200 °C) during the later mineralisation stage; and (3) stage III, seawater alteration that caused the precipitation of uraninite and chalcocite. This indicates that the fluids in the AVF had decreasing temperature and ƒS2 and increasing ƒO2 as mineralisation proceeded. The Cu-rich sulfide samples have mineral assemblages and a paragenesis similar to those of the Fe–Cu-rich sulfide samples, but the higher proportion of isocubanite is indicative of relatively high-temperatures and reducing conditions during mineralisation. Bulk chemical compositions of the AVF sulfides are characterised by high U contents (up to 51.9 ppm) and a distinct Sn distribution (2.1–86.4 ppm) between the two different types of hydrothermal samples, which differ from those of other ultramafic-hosted sulfide deposits. The U content is controlled mainly by the precipitation of discrete uraninite grains (< 1 μm in size) on altered surfaces of pyrite and hematite. The oxidative alteration of Fe-bearing minerals caused the fixation of seawater-derived U. Laser ablation–inductively coupled plasma–mass spectrometry analysis showed that most trace elements occur in solid solution in the sulfide minerals, mainly controlled by the physicochemical conditions of the hydrothermal fluids (e.g. temperature, ƒS2, and ƒO2). In particular, a comparative analysis of other mid-ocean ridge systems shows that the ultramafic-hosted sphalerite and pyrite are more enriched in Sn as compared with those hosted by basaltic rocks. However, the Fe–Cu-rich sulfide samples of the AVF are Sn-poor (< 10.2 ppm), because pyrite is substantially depleted in Sn (mostly < 1 ppm) as compared with sphalerite, regardless of the effect of the ultramafic-hosted mineralisation. This indicates that in situ trace element analysis of sphalerite and pyrite, especially for Sn, can provide insights into the different hydrothermal mineralisation in basaltic- and ultramafic-hosted systems, which cannot necessarily be inferred from bulk analysis. Our comparison also suggests that the Sn contents of ultramafic-hosted SMS deposits would be a possible source of Sn for the ultramafic-hosted volcanogenic massive sulfide (UM-VMS) deposit. The δ34S values (+ 6.2 to + 8.5‰) of the pyrite record thermochemical sulfate reduction of seawater, which suggests that sulfur and most metals were predominantly leached from the associated host rocks with a contribution (29–40%) from reduced seawater sulfur. In conclusion, the AVF is a rock-dominated system that contains ultramafic-hosted mineralisation in the Central Indian Ridge.

The Influence of Various Adhesive Systems and Polishing Methods on Enamel Surface Roughness after Debonding of Orthodontic Brackets: A Three-Dimensional In Vitro Evaluation.

A slight alteration of the enamel surface is inevitable upon debonding of orthodontic brackets, adhesive removal, and finishing/polishing. The aim of this in vitro study was to compare two adhesives and three polishing methods by measuring enamel surface roughness using confocal laser scanning microscopy (CLSM). Brackets were bonded on 42 extracted human premolars using Transbond XT (Transbond group) or Fuji Ortho (Fuji group). After debracketing, adhesives were removed with a tungsten carbide bur, and surfaces were polished using Sof-Lex discs, a rotary brush with a prophylactic paste (Depural), or a prophylactic cup with two polishing pastes (n = 7 in each subgroup). Surface roughness (Sa, Sku, Sq, and Sz) was measured using CLSM and compared before treatment (T1), after debracketing and adhesive removal (T2), and after polishing (T3). The data were statistically analyzed using the Mann-Whitney U and Kruskal-Wallis tests with Bonferroni correction. The time required for adhesive removal was measured and compared using a two-sample t-test. Surface roughness at T2 increased compared to T1, but the difference was significant only for the Fuji group (p < 0.01). The time required to remove Transbond XT (94.1 ± 6.8 s) was significantly higher compared to Fuji (72.1 ± 5.9 s, p < 0.0001). Polishing with Sof-Lex discs resulted in lower surface roughness compared to T1 (p = 0.018). Using Depural and polishing pastes showed no significant difference in surface roughness compared to T1, except for a significant decrease in Sa and Sq for Transbond (p = 0.043) and in Sku for Fuji (p = 0.018) after polishing with Depural. In conclusion, the removal of Transbond took significantly longer, but there were fewer residues of composite resin on the enamel surface. Sof-Lex discs decreased enamel roughness, whereas enamel morphology and roughness were similar to the pre-treatment state after polishing with polishing pastes.

Glucose metabolism and its role in the maturation and migration of human CD1c+ dendritic cells following exposure to BCG.

Tuberculosis (TB) still kills over 1 million people annually. The only approved vaccine, BCG, prevents disseminated disease in children but shows low efficacy at preventing pulmonary TB. Myeloid dendritic cells (mDCs) are promising targets for vaccines and immunotherapies to combat infectious diseases due to their essential role in linking innate and adaptive immune responses. DCs undergo metabolic reprogramming following exposure to TLR agonists, which is thought to be a prerequisite for a successful host response to infection. We hypothesized that metabolic rewiring also plays a vital role in the maturation and migration of DCs stimulated with BCG. Consequently, we investigated the role of glycolysis in the activation of primary human myeloid CD1c+ DCs in response to BCG. We show that CD1c+ mDC mature and acquire a more energetic phenotype upon challenge with BCG. Pharmacological inhibition of glycolysis with 2-deoxy-D-glucose (2-DG) decreased cytokine secretion and altered cell surface expression of both CD40 and CCR7 on BCG-challenged, compared to untreated, mDCs. Furthermore, inhibition of glycolysis had differential effects on infected and uninfected bystander mDCs in BCG-challenged cultures. For example, CCR7 expression was increased by 2-DG treatment following challenge with BCG and this increase in expression was seen only in BCG-infected mDCs. Moreover, although 2-DG treatment inhibited CCR7-mediated migration of bystander CD1C+ DCs in a transwell assay, migration of BCG-infected cells proceeded independently of glycolysis. Our results provide the first evidence that glycolysis plays divergent roles in the maturation and migration of human CD1c+ mDC exposed to BCG, segregating with infection status. Further investigation of cellular metabolism in DC subsets will be required to determine whether glycolysis can be targeted to elicit better protective immunity against Mtb.

Identification of pegmatites zones in Muiane and Naipa (Mozambique) from Sentinel-2 images, using band combinations, band ratios, PCA and supervised classification

Remote sensing has been widely used in Geological Sciences for different applications, such as to identify geological and mineralogical objects and surface alteration changes. This study aimed to analyze the Sentinel-2 potential to detect pegmatite bodies and associated alteration zones in Muiane and Naipa in Mozambique. Different remote sensing techniques were applied to a Sentinel-2 image: RGB combinations, band ratios, principal component analysis (PCA), and supervised image classification algorithms such as the Maximum Likelihood Classifier (MLC) and Support Vector Machine (SVM). MLC was used as a benchmark classifier to evaluate the performance of SVM because MLC is the predominant algorithm employed in remote sensing classification studies. For that, several statistical metrics based on the confusion matrices were computed, namely accuracy, Kappa index, precision, recall, and f-score, among others. This study allows identifying the location of pegmatites by direct identification and segregating between hydrothermally altered zones and non-altered areas through remote sensing data/techniques, supported by field data. The field campaigns allowed for validating the results obtained and verifying the pegmatites identified using Sentinel-2 data that were not previously mapped. Moreover, reflectance spectroscopy studies in the laboratory were conducted on the samples collected in the field campaigns allow to validate the adequacy of the methodology proposed in this study. The results show that the precise identification of pegmatite targets requires a high spatial resolution such as Sentinel-2 images. Thus, with the integration of high spatial and spectral resolution data, a potential level of precision and accuracy can be achieved in the study areas.

Experimental and numerical investigations on the effect of a novel internal surface micro-grooving toward improving convective heat transfer performance of tube heat exchangers

In the present work, the use of passive heat transfer enhancement technique through surface alteration was explored. The enhancement was achieved through internal conduit surface micro-grooving using a new apparatus that was developed by modifying a magnetic abrasive finishing technique. A new surface profile was created and later verified using optical and laser profiler measurements. The new profile was numerically investigated to compare the heat transfer and hydrodynamic performance against other profiles that have been studied in the literature. It was found from the results that the new profile shows much higher heat transfer improvement and comparable pressure loss to the previously investigated profiles (i.e., square, rectangular, trapezoidal, and circular). Overall, the new groove geometry provides the highest performance followed by the circular, triangular, curvy, square, and rectangular grooves. Also, the results indicate that designs with a smooth profile performs better than those with sharp edges, owing to the elimination of stationary fluid spots within the grooves. The effectiveness between the profiles was compared based on the level of heat transfer enhancement against the flow penalty. Experimental validation was further conducted for the experimentally generated groove. The results revealed that a relatively small surface temperature drop was obtained, corresponding to a slight improvement in heat transfer. This confirms the results generated by the simulation that groove size plays a major role in attaining significant improvement in heat transfer.