Mat Surface Research Articles

Supervised segmentation of RTI appearance attributes for change detection on cultural heritage surfaces

This paper proposes a supervised segmentation method for detecting surface changes based on appearance attributes, focusing on cultural heritage metal surfaces. Reflectance Transformation Imaging (RTI) reconstruction coefficients (PTM and HSH) are explored for tracking changes over time on different data sets. Each acquisition is normalised to ensure the method’s robustness, allowing consecutive acquisitions with different RTI acquisition parameters. The proposed method requires expert labelling on groups of pixels representing individual classes. Afterward, the surface appearance is identified over time based on the estimated discriminant model. After segmentation, each detected category is assigned to a single colour to present the results with a user-friendly colourmap visualisation. The method is user-dependent; the labelling of the pixels must be accurately defined based on the research question. The results were evaluated based on human expertise in the conservation-restoration field and are considered ground truth in this work. A case study with visibly segmentable characteristics was used to prove the concept and evaluate the invariance of the proposed method. Comparison with the segmentation of the visible characteristics shows very accurate segmentation for HSH (99%) and lower for PTM (80%), which is influenced by surface rotation. The method was tested on metal surfaces undergoing accelerated corrosion or cleaning treatments. The results were promising for tracking changes based on segmentation. Equally promising is the possibility of qualitative quantifying the degree of change by counting the change of a selected class of pixels. PTM and HSH results are comparable in cases of mat surfaces; however, in high specular surfaces, HSH seems to provide more detailed information and, therefore, can better depict the surface characteristics. Limitations of the application are related to the possibility of identifying surface characteristics that do not exhibit topographic changes or significant reflectance differentiation.

Janus and Heteromodulus Elastomeric Fiber Mats Feature Regulable Stress Redistribution for Boosted Strain Sensing Performance.

Wearable strain sensors have huge potential for applications in healthcare, human-machine interfacing, and augmented reality systems. However, the nonlinear response of the resistance signal to strain has caused considerable difficulty and complexity in data processing and signal transformation, thus impeding their practical applications severely. Herein, we propose a simple way to achieve linear and reproducible resistive signals responding to strain in a relatively wide strain range for flexible strain sensors, which is achieved via the fabrication of Janus and heteromodulus elastomeric fiber mats with micropatterns using microimprinting second processing technology. In detail, both isotropic and anisotropic fiber mats can turn into Janus fiber mats with periodical and heteromodulus micropatterns via controlling the fiber fusion and the diffusion of local macromolecular chains of thermoplastic elastomers. The Janus heterogeneous microstructure allows for stress redistribution upon stretching, thus leading to lower strain hysteresis and improved linearity of resistive signal. Moreover, tunable sensing performance can be achieved by tailoring the size of the micropatterns on the fiber mat surface and the fiber anisotropy. The Janus mat strain sensors with high signal linearity and good reproducibility have a very low strain detection limit, enabling potential applications in human-machine interfacing and intelligent control fields if combined with a wireless communication module.

The novel approach to physico-chemical modification and cytocompatibility enhancement of fibrous polycaprolactone (PCL) scaffolds using soft X-ray/extreme ultraviolet (SXR/EUV) radiation and low-temperature, SXR/EUV induced, nitrogen and oxygen plasmas

The fundamental aspect of the fabrication of microporous, fibrous biomaterials in form of scaffolds is the optimization of their surface properties to enhance cellular response. In this work, a novel approach to physico-chemical modification and bioactivity enhancement of electrospun fibrous polycaprolactone (PCL) nonwovens using soft X-ray/extreme ultraviolet (SXR/EUV) irradiation and exposure to a low-temperature, SXR/EUV induced, nitrogen and oxygen plasmas is presented for the first time.Chemical alterations and morphology of the fibrous structure of irradiated PCL mats were examined using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), respectively. The impact of introduced changes on viability, morphology, and adhesion of L929 mouse fibroblasts was examined. It was found that simultaneous interaction of SXR/EUV radiation and N2 or O2 photoionized plasmas led to strong chemical decomposition of the surface of fibrous PCL mats. Also, mats’ spatial porous structure was not damaged and the fibers were not broken or fused. All modified samples demonstrated cyto-compatible and non-cytotoxic properties. Enhancement of L929 cell adhesion and increased proliferation were also observed.

Cross‐linked electrospun polyvinyl alcohol/sodium caseinate nanofibers for antibacterial applications

AbstractIn this study, the polyvinyl alcohol (PVA) and sodium caseinate (SC) nanofibers were produced by a single‐fluid electrospinning method from their blends. Afterward, the cross‐linking process with two different methods was applied to the PVA/SC (70/30, v/v) ratio, which was selected according to the surface and mechanical properties of the electrospun mat. In the first method, different ratios (15%, 20%, 25%, and 30%) of glutaraldehyde (GLA) cross‐linking agents were added to the PVA/SC solution and then, PVA/SC/GLA nanofibers were obtained. In the second method (in‐situ method), the nanofibers obtained from the PVA/SC solution were cross‐linked by dipping into the cross‐linking solution. After, PVA/SC/GLA/Zinc oxide nanoparticles (ZnO NP) mats were obtained by adding ZnO NP at different rates to the PVA/SC/GLA (7030‐25GLA) solution, which was chosen according to the results of thermal, mechanical, and moisture test. In addition, performing tests, a cytotoxicity test for fibroblast cell line (L929), and in vitro antibacterial test for Escherichia coli and Staphylococcus aureus were also applied to them. Therefore, the usability of PVA/SC/GLA/ZnO NP nanofibers as an antibacterial effective wound dressing was investigated. Due to the high toxic effect of GLA, it was found that PVA/SC/ZnO cross‐linked nanofibers are not suitable for wound dressing use. However, it was determined that the PVA/SC nanofiber cross‐linked by the in‐situ method had high cell viability according to the cytotoxicity test result and thus could be used as a fibroblast tissue scaffold.

Near-Infrared Responsive Synergistic Chemo-Phototherapy from Surface-Functionalized Poly(ε-caprolactone)-Poly(d,l-lactic-co-glycolic acid) Composite Nanofibers for Postsurgical Cancer Treatment.

The combination of hyperthermia and chemotherapy has attracted significant attention in local cancer treatment following surgical resection. Pyrrole is a potent photothermal agent that can induce a temperature rise at different concentrations in the surrounding medium by absorbing near-infrared radiation (NIR). In this study, poly(ε-caprolactone) (PCL) and poly (d,l-lactic-co-glycolic acid) (PLGA) were used to make nanofibers using the electrospinning process. Then, pyrrole in different concentrations of (0.2, 0.4, and 0.6) M was attached to the surface of PCL-PLGA fiber mats by in situ polymerization, which was confirmed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) analysis. A concentration-dependent local temperature rise was observed using a FLIR camera under near-infrared (NIR) laser irradiation. For the hyperthermia effect, pyrrole concentration (0.06 M) was used for in vitro drug release studies and cell viability assays because under NIR irradiation (2 W/cm2, 3 min), it increased the local temperature to around 45 °C. In vitro drug release studies confirmed that NIR irradiation increased the diffusion rate of doxorubicin (DOX) by increasing the environmental temperature above the glass transition temperature of PLGA. In vitro cytotoxicity experiments further confirmed that PCL-PLGA-DOX/PPy fiber mats showed an enhanced inhibitory effect against CT26 and MCF7 cells by the combination of hyperthermia and chemotherapy.

Effects of Irradiance and Temperature on the Photosynthesis of the Crustose Coralline Algae Pneophyllum fragile (Corallinales, Rhodophyta) in the Coastal Waters of Korea

We investigated the photosynthetic characteristics of the crustose coralline alga Pneophyllum fragile (Corallinales, Rhodophyta) according to elevated water temperature and irradiance on the coast of Jeju in 2018. P. fragile was cultured under different temperature (11 °C, 21 °C, 26 °C, and 31 °C) and irradiance (0–1250 μmol photon m−2 s−1) conditions. Oxygen (O2) concentrations at the P. fragile mat–water interface (MWI) were measured using an O2 microsensor. At the MWI, the diffusive boundary layer thicknesses ranged from 200 to 400 μm. The O2 concentrations at the mat surface increased in response to increasing irradiance, and reached 344% air saturation. The maximum photosynthesis capacity (Pmax) and respiration rate in the dark (Rd) at 31 °C were about 3 times higher than those recorded at 11 °C. The compensation irradiance (Ec) and saturation irradiance (Ek) increased with increasing water temperature. The Pmax, Rd, and Ec were statistically correlated with temperature (p < 0.05). The Ek increased up to 833 μmol photon m−2 s−1 at 31 °C and exhibited a strong dependence on irradiance at high temperatures. The adaptability of P. fragile to high temperatures and strong irradiance was distinct from that observed for coralline algae in other temperate waters.

Ultrathin flexible electrospun EVA nanofiber composite with electrothermally-driven shape memory effect for electromagnetic interference shielding

When a 5G folding mobile phone is in a complex electromagnetic environment, it will unavoidably be subject to electromagnetic interference with a frequency of 450 MHz–6 GHz from electronic components on internal and external flexible printed circuits (FPCs). Here, we propose a method to prepare ultrathin, flexible and conductive polymer fiber composite (CPFC) with excellent shape memory effect and superb electromagnetic interference shielding effectiveness (EMI SE). The shape-memorized CPFC (SMCPFC) can be fabricated by three steps: (1) preparing highly cross-linked ethylene–vinyl acetate copolymer (EVA) fiber membrane by electrospinning and UV cross-linking; (2) synthesizing a polydopamine (PDA) layer on mat surface; (3) promoting the reduction of Ag nanoparticles on EVA@PDA fibrous composite surface. The electrical conductivity of SMCPFC can reach up to 2.5 × 105 S/m, and its average EMI SE is close to 90 dB at the frequency of 3.94–5.99 GHz. After cyclic stretching, folding, and ultrasonic washing, the conductivity and EMI SE maintains unchanged. In addition, SMCPFC has an outstanding electrothermally-driven shape memory effect. Shape can be programmed immediately at 0.55 V, and 50% strain sample exhibits EMI SE of 50.91 dB, which can blocks more than 99.99% electromagnetic waves. Shape can be recovered at 80 °C, EMI SE of recovery sample is roughly the same as that of the original sample (87.06 dB), and 99.9999997% electromagnetic waves can be consumed. The invention of this multifunctional SMCPFC gives a new way for FPC electromagnetic shielding film to develop towards the directions of intelligence and multi-functions.

A Cyanobacteria Enriched Layer of Shark Bay Stromatolites Reveals a New Acaryochloris Strain Living in Near Infrared Light.

The genus Acaryochloris is unique among phototrophic organisms due to the dominance of chlorophyll d in its photosynthetic reaction centres and light-harvesting proteins. This allows Acaryochloris to capture light energy for photosynthesis over an extended spectrum of up to ~760 nm in the near infra-red (NIR) spectrum. Acaryochloris sp. has been reported in a variety of ecological niches, ranging from polar to tropical shallow aquatic sites. Here, we report a new Acarychloris strain isolated from an NIR-enriched stratified microbial layer 4–6 mm under the surface of stromatolite mats located in the Hamelin Pool of Shark Bay, Western Australia. Pigment analysis by spectrometry/fluorometry, flow cytometry and spectral confocal microscopy identifies unique patterns in pigment content that likely reflect niche adaption. For example, unlike the original A. marina species (type strain MBIC11017), this new strain, Acarychloris LARK001, shows little change in the chlorophyll d/a ratio in response to changes in light wavelength, displays a different Fv/Fm response and lacks detectable levels of phycocyanin. Indeed, 16S rRNA analysis supports the identity of the A. marina LARK001 strain as close to but distinct from from the A. marina HICR111A strain first isolated from Heron Island and previously found on the Great Barrier Reef under coral rubble on the reef flat. Taken together, A. marina LARK001 is a new cyanobacterial strain adapted to the stromatolite mats in Shark Bay.

What Happens Between Depositional Events, Stays Between Depositional Events: The Significance of Organic Mat Surfaces in the Capture of Ediacara Communities and the Sedimentary Rocks That Preserve Them

In the absence of complex, bioturbating organisms, the seafloor during the Precambrian was covered in widespread organic matgrounds. The greatest diversity and complexity of organic mat textures occur in the Ediacaran fossil record as exemplified by the Ediacara Member of the Rawnsley Quartzite, which crops out in and around the Flinders Ranges, South Australia. This succession unambiguously demonstrates that heterogenous mats coexisted with and were central to the ecology and biology of the Ediacara Biota. Excavation of 33 fossiliferous beds with varying types and extents of organosedimentary surface textures provide the opportunity to utilize this record to develop criteria to evaluate the maturity or extent of growth of Ediacaran matgrounds and, using these characteristics, to examine the relationship between mat type, mat maturity and Ediacara Biota community structure. Based on the assumption that mat maturity represents an indicator of the duration of time between burial events, we can test predictions about the relationship between mat maturity and community development. We find that mat maturity, rather than the mat type itself, more strongly influenced the distribution of taxa and the development of Ediacara macroorganism communities. Using a ranked Mat Maturity Index, we find that although density of macroscopic body fossils and genus diversity correlate with mat maturity, evenness does not. We additionally find that the sessile taxa Obamus and Coronacollina are restricted to surfaces with mature mats whereas all other Ediacaran macrobiota show no connection to mat occurrence and maturity. However, we do observe that large Dickinsonia are more likely to occur on surfaces recording mature matgrounds. The exceptional record of mat surfaces preserved in the Flinders Ranges area demonstrates that, in addition to the apparent ecological role played by mat surfaces in Ediacaran communities, they were also likely a significant component of the Ediacara Member biomass and were integral to community function.

Potential use of metalworking fluid as surface additive for improving surface properties, technological properties, and formaldehyde emission of fiberboard

This study investigated the potential use of metalworking (cutting) fluid as an surface additive in the production of medium density fiberboard (MDF). The cutting fluid was sprayed on the mat surface of the fiberboard at different loading levels, of 3.5 g/m2, 7 g/m2, and 14 g/m2 (5 wt% or 10 wt% concentration levels) before the hot pressing. Some physical and mechanical properties of the resulting MDF specimens were carried out according to European standards. The bending strength and bending modulus, internal bond strength improved with the addition of the cutting fluid into the surface layers while the thickness swelling and water absorption decreased. This might be related to the fact that there was no hydrophobic chemical used in the production. The improvement in the adhesive bond between the fibers may be explained by the enhanced heat transfer from surface to the core layer of the MDF. The formaldehyde emission of the MDFs decreased with the incorporation of the cutting fluid. It was estimated that the crosslinking of the UF resin increased due to the higher thermal conductivity of the cutting fluid. The preliminary findings of the present study showed that the cutting fluid used in the metal industry could be efficiently used as surface additive in the production of the MDF.

Poly (ε-caprolactone)/Poly (lactic acid) fibers produced by rotary jet spinning for skin dressing with antimicrobial activity.

The rotary jet spinning technique permits the production of biomaterials that can be used as devices that come into contact with biological systems (including biological fluids) for diagnostic or surgical applications. These materials are composed of synthetic or natural compounds and allow the incorporation of drugs for therapeutic purposes. Two solutions containing 50% poly(lactic acid) (PLA) and 50% poly(ε-caprolactone) (PCL) diluted in three different solvents were prepared for rotary jet spinning (RJS) process. Vancomycin, an antibiotic indicated for the treatment of severe staphylococcal infections in patients with penicillin allergy, was added in the polymer solutions, to obtain drug-loaded fibrous mats. Morphological surface characterization by scanning electron microscopy revealed heterogeneous pores in the microfibers. Vancomycin loading interfered with the morphology of all samples in terms of fiber size, leading to smaller diameter fibers. Attenuated total reflectance/Fourier transform infrared spectroscopy was used for identification of the samples. The vibrational characteristics of PCL/PLA and vancomycin were consistent with expectations. Vero cell culture assays by the extract dilution and direct contact methods revealed the absence of cytotoxicity, except for the sample prepared with 50% of PCL and of a 9/2 (V/V) vancomycin content, with the growth of confluent and evenly spread cells on the fibrous mats surface. Microbiological analysis, performed on Staphylococcus aureus by the halo inhibition test and by the broth dilution method, showed that the antibacterial activity of vancomycin was maintained by the loading process in the polymer fibers. The results showed that rotary jet spinning produces satisfactory amounts of Vancomycin-loaded fibers, as potential web dressing for wound repair.

Immediate effects of stretching on trunk functions using a stretch pole half-cut.

[Purpose] To analyze the immediate effects of stretching on respiratory and trunk functions using a stretch pole half-cut in healthy male participants. [Participants and Methods] Thirty healthy male participants with a mean age of 21.1 ± 0.8 years were recruited in this study. The participant had to lay on his back on the convex surface of the pole with the semicircle of the pole touching the surface of the platform mat. The convex of the pole was placed at the level from seventh to 10th thoracic vertebra for 4 min and was applied perpendicular (anatomically horizontal) to the body axis. Respiratory function and muscle strength using a spirometer with attached units, maximum-minimum chest wall expansion difference using a tape measure, and body alignment, such as angles obtained from the spinal mouse, were measured before and immediately after the intervention in random order. [Results] The total inclination angle was found to decrease significantly, while the thoracic kyphosis angle and maximum inspiratory pressure showed a significant increase. [Conclusion] This intervention was suggested to be easy for incorporating into day life and useful in situations where the subjects want to increase the maximum inspiratory pressure, such as in sports.

Characterization of microporous PP/PE nonwoven mats surface modified by deposition of electrospun nanofibers

This study investigates the effect of surface modification by deposition of electrospun fibers on properties and performance of three different microporous polypropylene/polyethylene (PP/PE) commercial nonwoven membrane supports (Novatexx 2430, 2465 and 2473). Polyamide (nylon 6) nanofiber webs with a small number of defects and fibers of about 100 nanometer diameter were successfully deposited onto a surface of the selected membrane supports. FESEM was used to examine microstructure and morphology of the unmodified substrates and the prepared composite two-layer membranes. DSC was applied to investigate thermal stability and FT-IR analysis to confirm the chemical composition of the studied membranes. Saline water permeability tests of the prepared two-layer composite membranes were carried out. The largest pressure difference was measured for PA nanofiber/Novatexx 2430 sample, which was ascribed to a denser net structure of the membrane support and possibly to the newly formed layer of dissolved salts on the membrane surface.

Water-Evaporation-Induced Electric Generator Built from Carbonized Electrospun Polyacrylonitrile Nanofiber Mats.

Electricity has been generated from evaporation-driven water flow in films of carbon soot particles and other porous media. This paper reports the placement of carbon nanofiber mats (CNMs) on fiberglass screens for the construction of efficient water-evaporation-induced generators (WEIGs). These CNMs are prepared from carbonizing electrospun polyacrylonitrile nanofiber mats and then treating them with oxygen plasma. After electrode attachment to the two ends of a CNM, one electrode is immersed into water. Water rises in the mat due to capillary action and evaporates from the mat surface due to thermal energy provided by the environment. The steady rise of water pushes the dissociated ions of the surface functionalities upward, resulting in a streaming current and an electric potential. This paper investigates how the generated short-circuit current, Is, and open-circuit voltage, Vo, of the WEIG change with structural parameters of the CNMs. Under optimized conditions, these CNMs produce electricity at an areal power density of 83 nW/cm2, which is almost 10 times those offered by some existing ones. Thus, the easy-to-handle CNMs are an attractive porous scaffold for WEIGs.

The Influence of Target Properties on the Accuracy of Reflectorless Distance Measurements.

Recent years have brought dynamic developments in surveying equipment and techniques. These include reflectorless electromagnetic distance measurement (RL EDM), which is used in a range of devices, especially total stations. Studies concerning the influence of the reflecting surface on the accuracy of RL EDM tend to focus on the colour of the measurement surface, while the influence of the density and thickness of materials is usually neglected. Therefore, this study undertook to examine 53 samples representing various materials of dissimilar features: colour, type of surface and density. The results show that dark and mat surfaces cause higher RL EDM errors than bright, gloss materials. Nonetheless, 76% of the results were in compliance with equipment specifications. Moreover, it was found that the density of the samples had significant impact on the overall accuracy. RL EDM to EPS (expanded polystyrene sheets, low-density material, commonly called Styrofoam) involved a significantly higher error rate. It demonstrates that total station measurements and laser scanning should be performed cautiously, especially with regard to materials of low density (e.g., EPS) and on short distances, where the value of relative error is high.

Promising antibacterial effect of impregnated nanofiber mats with a green nanogel against clinical and standard strains of Pseudomonas aeruginosa and Staphylococcus aureus

Pseudomonas aeruginosa and Staphylococcus aureus are two important pathogens that cause many maladies such as skin diseases in humans. Resistance to common antibiotics is a major challenge for health care systems worldwide; new green antibacterial agents have become crucial. In this study, ingredients of Mentha longifolia essential oil were first investigated; pulegone (46.97%), eucalyptol (12.22%), piperitenone (6.13%), carvone (4.16%), and limonene (3.42%) were identified as five major ingredients. Electrospun nanofibers of polycaprolactone-alginate nanofibers with 188 (±36) nm diameter were then prepared. The nanofibers were characterized using ATR-FTIR analysis, SEM analysis, and water contact angle meter. They did not show cytotoxic effects on HFFF2 cells, a human skin normal cell line. After that, a nanoemulsion-based nanogel of M. longifolia EO was prepared and physically impregnated on the surface of the nanofibers mats. Antibacterial effects of the prepared prototype at three concentrations (2.5, 5, and 10 mg/mL) with exposure times of 1, 3, and 24 h were investigated against clinical and standard strains of P. aeruginosa and S. aureus. At a 5 mg/mL concentration with 1 h exposure, the growth of a standard strain of P. aeruginosa ∼80% was decreased. After increasing exposure time to 24 h, growth of both standard and clinical strains ∼90% reduced. Furthermore, at a 10 mg/mL concentration with exposure times of 3 and 24 h, ∼100% reduction in the growth of all exanimated bacteria strains was observed. The prepared prototype could thus be used as a green potent antibacterial agent as a wound dressing and cleaning pad.

New insights in bacterial and eukaryotic diversity of microbial mats inhabiting exploited and abandoned salterns at the Ré Island (France)

In order to understand the effect of human practices on microbial mats organisation, the study aimed to investigate the biodiversity within microbial mats from exploited and abandoned salterns. Despite several attempts, archaeal 16S rRNA gene fragment sequences were not obtained, indicating that microbial mats were probably dominated by Bacteria with very low abundance of Archaea (< 1%). Thus, the study compared the bacterial and meiofaunal diversity of microbial mats from abandoned and exploited salterns. The higher salinity (101 ± 3.7 psu vs. 51.1 ± 0.7 psu; Welch t-test p < 0.05) of the exploited site maintained lower bacterial diversity in comparison to the abandoned site where the salinity gradient was no longer maintained. However, the microbial mats exhibited similar bacterial class composition while the eukaryotic diversity was significantly higher in the exploited saltern. The abandoned saltern was dominated by sulfate-reducing bacteria and Nematoda, while the exploited saltern was characterized by the presence of halophilic bacteria belonging to Marinobacter, Salinivibrio and Rhodohalobacter genera, and the larger abundance of Hypotrichia (ciliates). Such bacterial and eukaryotic diversity difference might be explained by human actions for salt recovery in exploited salterns such as scraping the surface of microbial mat and increasing salinity renewing the microbial mat each year. Such action decreases the bacterial diversity changing the food web structure that favour the presence of a larger diversity of eukaryotic organisms. Our study provides new insights on microbial mat communities inhabiting salterns, especially the consequences of abandoning saltern exploitation.

Sedimentary pyrite sulfur isotope compositions preserve signatures of the surface microbial mat environment in sediments underlying low-oxygen cyanobacterial mats.

The sedimentary pyrite sulfur isotope (δ34 S) record is an archive of ancient microbial sulfur cycling and environmental conditions. Interpretations of pyrite δ34 S signatures in sediments deposited in microbial mat ecosystems are based on studies of modern microbial mat porewater sulfide δ34 S geochemistry. Pyrite δ34 S values often capture δ34 S signatures of porewater sulfide at the location of pyrite formation. However, microbial mats are dynamic environments in which biogeochemical cycling shifts vertically on diurnal cycles. Therefore, there is a need to study how the location of pyrite formation impacts pyrite δ34 S patterns in these dynamic systems. Here, we present diurnal porewater sulfide δ34 S trends and δ34 S values of pyrite and iron monosulfides from Middle Island Sinkhole, Lake Huron. The sediment-water interface of this sinkhole hosts a low-oxygen cyanobacterial mat ecosystem, which serves as a useful location to explore preservation of sedimentary pyrite δ34 S signatures in early Earth environments. Porewater sulfide δ34 S values vary by up to ~25‰ throughout the day due to light-driven changes in surface microbial community activity that propagate downwards, affecting porewater geochemistry as deep as 7.5cm in the sediment. Progressive consumption of the sulfate reservoir drives δ34 S variability, instead of variations in average cell-specific sulfate reduction rates and/or sulfide oxidation at different depths in the sediment. The δ34 S values of pyrite are similar to porewater sulfide δ34 S values near the mat surface. We suggest that oxidative sulfur cycling and other microbial activity promote pyrite formation in and immediately adjacent to the microbial mat and that iron geochemistry limits further pyrite formation with depth in the sediment. These results imply that primary δ34 S signatures of pyrite deposited in organic-rich, iron-poor microbial mat environments capture information about microbial sulfur cycling and environmental conditions at the mat surface and are only minimally affected by deeper sedimentary processes during early diagenesis.

Thermal Analysis of Heating–Cooling Mat of Textile Incubator for Infants

Abstract On the medical device market there are several types of stationary and portable incubators that can be used in the care of infants. The prototype of a textile incubator made as part of this work consists of five material layers. The textile incubator is equipped with a functional heating and cooling mat, which is made on the basis of 3D channeled weft-knitted fabric. Its function is to generate heat and maintain it inside the textile incubator or to cool the baby's body while using therapeutic hypothermia. The mat is equipped with hoses transporting the heating or cooling medium. The mat, depending on variable input parameters, can emit heat in the range from 1.15 W to 86.88 W. In case of the cooling function, it can receive heat in the range from −4.32 to −27.96 W. This indicates a large adjustment range of the amount of heat supplied and received, which is a positive feature, and enables programming the heat balance to ensure comfort for the baby. The analysis of temperature measurements on the mat surface confirmed that maximum temperature differences do not exceed 1.6°C.

Numerical Analysis of Ampicillin Release from Electrospun Nanofibrous Mats

The electrospun nanofibrous mat is an emerging tool for drug release studies. Therefore, it is essential to predict this type of system's drug release behavior to overcome the existing problems and generate novel drug release systems. In the present work, a numerical study is performed for fulfilling this requirement, and the current numerical data is validated with the experimental study, which is available in the open literature. Transient Langmuir-Freundlich adsorption-desorption isotherm is employed for describing the drug release behavior of the electrospun nanofibrous system under perfect sink conditions. The effect of the diffusion phenomenon is also taken into account. Drug release rates are investigated for different initial drug concentrations, porosity values, permittivity mass coefficients, and mat surface areas. Moreover, the relationship between the porosity and the initial drug concentration is also presented. It can be reported that significant alterations occur in drug release rates through varied initial drug concentrations and porosity. Although the drug release rate is altered with permittivity coefficient or surface area, minor variations are observed compared to the parameters above. The results of the numerical code agree well with the experimental data.