Resolving protein-mineral interfacial interactions during in vitro mineralization by atom probe tomography.

Organic macromolecules exert remarkable control over the nucleation and growth of inorganic crystallites during (bio)mineralization, as exemplified during enamel formation where the protein amelogenin regulates the formation of hydroxyapatite (HAP). However, it is poorly understood how fundamental processes at the organic-inorganic interface, such as protein adsorption and/or incorporation into minerals, regulates nucleation and crystal growth due to technical challenges in observing and characterizing mineral-bound organics at high-resolution. Here, atom probe tomography techniques were developed and applied to characterize amelogenin-mineralized HAP particles in vitro, revealing distinct organic-inorganic interfacial structures and processes at the nanoscale. Specifically, visualization of amelogenin across the mineralized particulate demonstrates protein can become entrapped during HAP crystal aggregation and fusion. Identification of protein signatures and structural interpretations were further supported by standards analyses, i.e., defined HAP surfaces with and without amelogenin adsorbed. These findings represent a significant advance in the characterization of interfacial structures and, more so, interpretation of fundamental organic-inorganic processes and mechanisms influencing crystal growth. Ultimately, this approach can be broadly applied to inform how potentially unique and diverse organic-inorganic interactions at different stages regulates the growth and evolution of various biominerals.

Microsized Pore Structure Determination in EPDM Rubbers Using High-Pressure 129Xe NMR Techniques.

Microsized pore parameters, such as pore size and distance between pores in a series of model EPDM rubbers, were determined in situ under the pressure of 500 psi using 129Xe nuclear magnetic resonance (NMR) techniques: spin-lattice (T1) and spin-spin (T2) relaxation measurements, pulsed-field gradient (PFG) NMR, and two-dimensional exchange spectroscopy (2D EXSY). The T1/T2 (≫1) ratio for the xenon confined in the pores is larger than that for nonconfined free xenon. This suggests that almost the entire pore surface interacts with xenon atoms like a closed pore. While these pores still connect each other through very narrow diffusion/exchange channels, it is possible to observe the echo decay in PFG-NMR and cross-peaks in 2D EXSY. The results show that both diffusion (Dpore ≈ 2.1 × 10-10 m2/s) and exchange (exchange rate, τexch = a few tens of milliseconds) of xenon between a pore within the material and outer surface are prolonged. The exchange distances (l), which correspond to the xenon gas penetration depth, were estimated to be 70-100 µm based on the measured diffusion coefficients and exchange rate (1/τexch). NMR diffraction analysis reveals that pore size (a) and pore distance (b) are on the order of magnitude of micrometers and tens of micrometers, while the diffusion coefficients of xenon gas in the diffusion channels (Deff) are about 10-8 m2/s. Overall, this study suggests that the pores with a few micrometers connected through very narrow flowing channels with the length of several tens of micrometers are developed 70 to 100 µm below the rubber surface. Furthermore, the overall steady-state diffusion of xenon is slower, approximately 2 orders of magnitudes, than the diffusion in the channel between the pores. The pore and exchange distances correlated with the composition of rubbers showed that the properties of EPDM rubber as a high-pressure gas barrier could be improved by reducing the size of cracks and the depth of gas penetration by the addition of both carbon black and silica fillers.

A Phenomenological Study of Nurses' Experience in Caring for COVID-19 Patients.

This study aimed to understand and describe the experiences of nurses who cared for patients with COVID-19. A descriptive phenomenological approach was used to collect data from individual in-depth interviews with 14 nurses, from 20 October 2020 to 15 January 2021. Data were analyzed using the phenomenological method of Colaizzi. Five theme clusters emerged from the analysis: (1) nurses struggling under the weight of dealing with infectious disease, (2) challenges added to difficult caring, (3) double suffering from patient care, (4) support for caring, and (5) expectations for post-COVID-19 life. The findings of this study are useful primary data for developing appropriate measures for health professionals' wellbeing during outbreaks of infectious diseases. Specifically, as nurses in this study struggled with mental as well as physical difficulties, it is suggested that future studies develop and apply mental health recovery programs for them. To be prepared for future infectious diseases and contribute to patient care, policymakers should improve the work environment, through various means, such as nurses' practice environment management and incentives.

Effects of alternating pressure air mattresses on pressure injury prevention: A systematic review of randomized controlled trials.

BACKGROUND: Pressure injury (PI) is a significant health problem among inpatients that affects their health, quality of life, and expenses. AIM: This systematic review aimed to compare effects of alternating pressure air mattresses (APMs) with other types of supporting surfaces as a tool for PI prevention. METHODS: The literature published between 2009 and 2020 was searched using the databases PubMed, EMBASE, CINAHL, and Cochrane. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses process was followed, including independent study selection and data extraction. Quality appraisal was conducted using the Cochrane Risk of Bias Tool (RoB 2.0). RESULTS: A total of six randomized controlled trials (RCTs) were analyzed. The incidence of hospital-acquired PIs at stage 1 or higher was reported in the APM group from 0.3% to 25%. In one study, APMs were found to be less effective than static air mattresses (SAMs); in contrast, two studies found no difference. In one study, the APM was reported to be more effective than the viscoelastic foam mattress (VFM). On the contrary, in a more recent study, the APM was reported to be less effective than the VFM, and there was no difference compared with high-specification foam mattresses in another study. Using the RoB 2.0 tool, one study was evaluated at "low risk of bias," another as "some concern," and four as "high risk." LINKING EVIDENCE TO ACTION: There is insufficient evidence to suggest that APM is more effective in preventing PIs than other supporting surfaces. Evidence to date suggests that APM can be used in patients at risk for PIs. It is important to change position regardless of the type of support surface used. Highly controlled RCTs with low risk of bias are needed to provide strong evidence for identifying the most effective PI prevention support surfaces.

A Comparative Study of 2-Hour Interface Pressure in Different Angles of Laterally Inclined, Supine, and Fowler's Position.

Insufficient research exists for position change intervals to eradicate pressure ulcers. We tried to provide evidence for the position change interval by comparing peak pressure, risk area ratio, and the time to reach 30 mmHg and 60 mmHg, and presented this in detail, according to the angle in the three positions. The study conducted RCTs on a total of 64 healthy adults. For two hours, interface pressure measurements were compared with 30° and 90° tilting at the inclined, 0° and 45° head-of-bed (HOB) elevation at the supine, and 30° and 45° HOB elevation at the Fowler's position. The peak pressure on 30° tilting remained less than 60 mmHg for 2 h, unlike 90° tilting. To reach 60 mmHg took 78.18 min at 30° tilting, within 30 min at the 30° supine, 30° and 45° at the Fowler's position, and 39.55 min at 0° supine. The pressure difference according to the angles was only significant at 30° and 90° tilting, with no difference in the other groups. To prevent pressure ulcers, position changes are required every 2 h in the 30° tilting position, every 1.5 to 2 h at 0° supine, and at least every 1.5 h for all the other positions.

Medical Adhesive-Related Skin Injury Associated with Surgical Wound Dressing among Spinal Surgery Patients: A Cross-Sectional Study.

The aim of this cross-sectional study was to determine the incidence, types, and factors associated with medical adhesive-related skin injuries (MARSIs) among spinal surgery patients. Adult patients who underwent planned spinal surgery under general anesthesia at a tertiary hospital in Seoul, Korea were enrolled. Data were collected from March through April 2019. Skins under surgical wound dressings were evaluated for MARSI once every morning until discharge. Skin injuries lasting for 30 min or more were considered as MARSIs. Logistic regression was performed to identify factors associated with MARSI. The incidence of MARSIs in surgical areas was 36.4% and the rate per 100 medical adhesives was 9.8%. All MARSIs occurred on postoperative day 1 or 2. A history of contact dermatitis (OR = 10.517, 95% CI = 3.540-31.241, p < 0.001) and late ambulation (OR = 1.053, 95% CI = 1.012-1.095, p = 0.010) were identified as risk factors for MARSI. Spinal surgery patients were at high risk of MARSIs associated with surgical wound dressings. Patients with a history of contact dermatitis or prolonged bed rest periods need more active skin assessment and more careful skin care to prevent MARSIs after spinal surgery.

Catalytic Reduction of Graphene Oxide Membranes and Water Selective Channel Formation in Water-Alcohol Separations.

Graphene oxide (GO) is a promising membrane system for chemical separation applications due to its 2-D nanofluidics properties and an ability to control interplanar spacing for selectivity. The permeance of water, methanol (MeOH) and isopropyl alcohol (IPA) through 5 µm thick membranes was found to be 0.38 ± 0.15, 0.33 ± 0.16 and 0.42 ± 0.31 LMH/bar (liter/m2·h·bar), respectively. Interestingly, the permeance of a water-alcohol mixture was found to be dramatically lower (~0.01 LMH/bar) than any of its components. Upon removing the solvent mixture, the transmembrane flux of the pure solvent was recovered to near the original permeance. The interlayer space of a dried GO membrane was found to be 8.52 Å, which increased to 12.19 Å. 13.26 Å and 16.20 Å upon addition of water, MeOH and IPA. A decrease in d-space, about 2 Å, was consistently observed when adding alcohol to water wetted GO membrane and an optical color change and reduction in permeance. A newly proposed mechanism of a partial reduction of GO through a catalytic reaction with the water-alcohol mixture is consistent with experimental observations.

Plant-based CO2 drawdown and storage as SiC.

Since the 1950's the Earth's natural carbon cycle has not sufficiently sequestrated excess atmospheric CO2 contributed by human activities. CO2 levels rose above 400 ppm in 2013 and are forecasted to exceed 500 ppm by 2070, a level last experienced during the Paleogene period 25-65 MYA. While humanity benefits from the extraction and combustion of carbon from Earth's crust, we have overlooked the impact on global climate change. Here, we present a strategy to mine atmospheric carbon to mitigate CO2 emissions and create economically lucrative green products. We employ an artificial carbon cycle where agricultural plants capture CO2 and the carbon is transformed into silicon carbide (SiC), a valuable commercial material. By carefully quantifying the process we show that 14% of plant-sequestered carbon is stored as SiC and estimate the scale needed for this process to have a global impact.

The effects of cryotherapy on perineal pain after childbirth: A systematic review and meta-analysis.

BACKGROUND: Most women experience perineal pain after childbirth. Sustained perineal pain affects mother's daily living. Various methods have been used to relieve postpartum perineal pain, such as cold or warm therapy, but the pain-control effects of cryotherapy are still controversial. AIMS: The purpose of this study was to verify the effectiveness of cryotherapy in relieving perineal pain in women after childbirth. METHODS: The researchers searched the CINAHL, Cochrane, EMBASE, PubMed, Korea Education and Research Information Service, NDSL, KoreaMed, LILACS and SciELO databases for studies to include in this review, and selected studies using PICO criteria. Methodological quality was assessed based on Cochrane's risk of bias 2 for randomized controlled trials. Data were analyzed with the Comprehensive Meta-Analysis program. FINDINGS: Eleven published studies encompassing 1,492 participants were included. Cryotherapy significantly reduced pain two days postpartum. Ice packs and gel packs had similar pain-relieving effects. Cryotherapy did not differ significantly from Epifoam therapy (hydrocortisone-pramoxine) in its effects on perineal pain one day or five days after childbirth. CONCLUSIONS: Cryotherapy can be an effective non-pharmacological nursing intervention to reduce pain after childbirth.

Cotton Fiber-Based Sorbents for Treating Crude Oil Spills.

Wood and plant fibers have been studied as natural sorbent materials for treating aquatic oil spills; however, the effectiveness of these materials is limited by their tendency to absorb water as well as oil. Chemical pretreatment of cotton fibers with fatty acids was examined as a means of enhancing the performance of cotton as a sorbent for crude oil. A raw cotton fiber was chemically modified with C18 fatty acid by simple leaving group chemistry. Free surface hydroxyl groups were modified with long alkyl chains to create fibers that displayed increased water contact angles, indicative of a significant decrease in surface energy. The increased affinity for oil and corresponding repulsion of water on the individual modified fibers translated to greater sorption of oil and rejection of water by loose assemblies of fibers (i.e., balls or yarn) when compared with unmodified cotton. X-ray diffraction (XRD) pattern, Fourier transform infrared (FT-IR), 13C cross-polarization/magic angle spinning solid-state nuclear magnetic resonance (CP/MAS SSNMR), and scanning electron microscopy (SEM) showed that cotton fibers were significantly exfoliated by the intercalation of C18 fatty acids about 2.4 times in its diameter. In the presence of seawater, the highly oleophilic C18 fatty acid-modified cotton fiber showed a maximum oil sorption capacity of 35.58 g per gram of fiber, about ∼49% greater than that of the corresponding raw cotton fiber.

Enhanced Capacities of Mixed Fatty Acid-Modified Sawdust Aggregators for Remediation of Crude Oil Spill.

Mixed fatty acid-modified aggregators have been developed as potential crude oil sorbents. Cheap pine wood flour was first modified with oleic acid (OA) and further modified with a second fatty acid by a leaving group chemistry, where a surface hydroxyl group is first replaced by p-toluenesulfonyl group and a fatty acid forms a covalent bond on sawdust surface through esterification at the elevated temperature (55 °C). Two OA-modified base materials, pine/OA-106 and pine/OA-124, with different OA-coverages were first prepared and the second fatty acids with C3, C6, C8, C10, C12, C14, or C16 alkyl chains were applied to cover the remaining surface hydroxyl groups. The crude oil sorption capacities of the mixed fatty acid-modified aggregators were studied and compared with those of the base materials. The results showed that mixed fatty acid-modified aggregators increased up to 45.6% more crude oil sorption than those of OA-modified base materials. A correlation between surface property and sorption capacity was studied by moisture sorption, Fourier transform infrared spectroscopy, X-ray diffraction, 13C cross polarization and magic angle spinning nuclear magnetic resonance, thermal gravimetric analysis, and scanning electron microscopy. To our knowledge, no report has been published for mixed fatty acid-modified herders or aggregators in the environmental remediation.

The energetic basis for hydroxyapatite mineralization by amelogenin variants provides insights into the origin of amelogenesis imperfecta.

Small variations in the primary amino acid sequence of extracellular matrix proteins can have profound effects on the biomineralization of hard tissues. For example, a change in one amino acid within the amelogenin protein can lead to drastic changes in enamel phenotype, resulting in amelogenesis imperfecta, enamel that is defective and easily damaged. Despite the importance of these undesirable phenotypes, there is very little understanding of how single amino acid variation in amelogenins can lead to malformed enamel. Here, we aim to develop a thermodynamic understanding of how protein variants can affect steps of the biomineralization process. High-resolution, in situ atomic force microscopy (AFM) showed that altering one amino acid within the murine amelogenin sequence (natural variants T21 and P41T, and experimental variant P71T) resulted in an increase in the quantity of protein adsorbed onto hydroxyapatite (HAP) and the formation of multiple protein layers. Quantitative analysis of the equilibrium adsorbate amounts revealed that the protein variants had higher oligomer-oligomer binding energies. MMP20 enzyme degradation and HAP mineralization studies showed that the amino acid variants slowed the degradation of amelogenin by MMP20 and inhibited the growth and phase transformation of HAP. We propose that the protein variants cause malformed enamel because they bind excessively to HAP and disrupt the normal HAP growth and enzymatic degradation processes. The in situ methods applied to determine the energetics of molecular level processes are powerful tools toward understanding the mechanisms of biomineralization.

Highly Selective Supported Graphene Oxide Membranes for Water-Ethanol Separation.

A polyethersulfone (PES)-supported graphene oxide (GO) membrane has been developed by a simple casting approach. This stable membrane is applied for ethanol/water separation at different temperatures. The 5.0 µm thick GO film coated on PES support membrane showed a long-term stability over a testing period of one month and excellent water/ethanol selectivity at elevated temperatures. The water/ethanol selectivity is dependent on ethanol weight percentage in water/ethanol feed mixtures and on operating temperature. The water/ethanol selectivity was enhanced with an increase of ethanol weight percentage in water/ethanol mixtures, from below 100 at RT to close to 874 at a 90 °C for 90% ethanol/10% water mixture. Molecular dynamics simulation of water-ethanol mixtures in graphene bilayers, that are considered to play a key role in transport, revealed that molecular transport is negligible for layer spacing below 1 nm. The differences in the diffusion of ethanol and water in the bilayer are not consistent with the large selectivity value experimentally observed. The entry of water and ethanol into the interlayer space may be the crucial step controlling the selectivity.

Hierarchically Porous Graphitic Carbon with Simultaneously High Surface Area and Colossal Pore Volume Engineered via Ice Templating.

Developing hierarchical porous carbon (HPC) materials with competing textural characteristics such as surface area and pore volume in one material is difficult to accomplish, particularly for an atomically ordered graphitic carbon. Herein we describe a synthesis strategy to engineer tunable HPC materials across micro-, meso-, and macroporous length scales, allowing the fabrication of a graphitic HPC material (HPC-G) with both very high surface area (>2500 m2/g) and pore volume (>11 cm3/g), the combination of which has not been attained previously. The mesopore volume alone for these materials is up to 7.53 cm3/g, the highest ever reported, higher than even any porous carbon's total pore volume, which for our HPC-G material was >11 cm3/g. This HPC-G material was explored for use both as a supercapacitor electrode and for oil adsorption, two applications that require either high surface area or large pore volume, textural properties that are typically exclusive to one another. We accomplished these high textural characteristics by employing ice templating not only as a route for macroporous formation but as a synergistic vehicle that enabled the significant loading of the mesoporous hard template. This design scheme for HPC-G materials can be utilized in broad applications, including electrochemical systems such as batteries and supercapacitors, sorbents, and catalyst supports, particularly supports where a high degree of thermal stability is required.

Double Epitaxy as a Paradigm for Templated Growth of Highly Ordered Three-Dimensional Mesophase Crystals.

Molecular templating and self-assembly are fundamental mechanisms for controlling the morphology of biominerals, while in synthetic two-dimensional layered materials similar levels of control over materials structure can be achieved through the epitaxial relationship with the substrate. In this study these two concepts are combined to provide an approach for the nucleation and growth of three-dimensional ordered mesophases on solid surfaces. A combined experimental and theoretical study revealed how atomic ordering of the substrate controls the structure of surfactant template and the orientation and morphology of the epitaxially grown inorganic material. This dual epitaxial relationship between the substrate, surfactant template, and inorganic mesophase gives rise to a highly ordered porous mesophase with a well-defined cubic lattice of pores. The level of control over the material's three-dimensional architecture achieved in this one-step synthesis is reminiscent of that in biomineralization.

Molecular Dynamics Simulations Reveal that Water Diffusion between Graphene Oxide Layers is Slow.

Membranes made of stacked layers of graphene oxide (GO) hold the tantalizing promise of revolutionizing desalination and water filtration if selective transport of molecules can be controlled. We present the findings of an integrated study that combines experiment and molecular dynamics simulation of water intercalated between GO layers. We simulated a range of hydration levels from 1 wt.% to 23.3 wt.% water. The interlayer spacing increased upon hydration from 0.8 nm to 1.1 nm. We also synthesized GO membranes that showed an increase in layer spacing from about 0.7 nm to 0.8 nm and an increase in mass of about 15% on hydration. Water diffusion through GO layers is an order of magnitude slower than that in bulk water, because of strong hydrogen bonded interactions. Most of the water molecules are bound to OH groups even at the highest hydration level. We observed large water clusters that could span graphitic regions, oxidized regions and holes that have been experimentally observed in GO. Slow interlayer diffusion can be consistent with experimentally observed water transport in GO if holes lead to a shorter path length than previously assumed and sorption serves as a key rate-limiting step.

Selective removal of cesium and strontium using porous frameworks from high level nuclear waste.

Efficient and cost-effective removal of radioactive (137)Cs and (90)Sr found in spent fuel is an important step for safe, long-term storage of nuclear waste. Solid-state materials such as resins and titanosilicate zeolites have been assessed for the removal of Cs and Sr from aqueous solutions, but there is room for improvement in terms of capacity and selectivity. Herein, we report the Cs(+) and Sr(2+) exchange potential of an ultra stable MOF, namely, MIL-101-SO3H, as a function of different contact times, concentrations, pH levels, and in the presence of competing ions. Our preliminary results suggest that MOFs with suitable ion exchange groups can be promising alternate materials for cesium and strontium removal.

Hierarchically structured catalysts for cascade and selective steam reforming/hydrodeoxygenation reactions.

We report a hierarchically structured catalyst with steam reforming and hydrodeoxygenation functionalities being deposited in the micropores and macropores, respectively. The catalyst is highly efficient to upgrade the pyrolysis vapors of pine forest product residual, resulting in a dramatically decreased acid content and increased hydrocarbon yield without external H2 supply.

Alexa fluor-labeled fluorescent cellulose nanocrystals for bioimaging solid cellulose in spatially structured microenvironments.

Methods to covalently conjugate Alexa Fluor dyes to cellulose nanocrystals, at limiting amounts that retain the overall structure of the nanocrystals as model cellulose materials, were developed using two approaches. In the first, aldehyde groups are created on the cellulose surfaces by reaction with limiting amounts of sodium periodate, a reaction well-known for oxidizing vicinal diols to create dialdehyde structures. Reductive amination reactions were then applied to bind Alexa Fluor dyes with terminal amino-groups on the linker section. In the absence of the reductive step, dye washes out of the nanocrystal suspension, whereas with the reductive step, a colored product is obtained with the characteristic spectral bands of the conjugated dye. In the second approach, Alexa Fluor dyes were modified to contain chloro-substituted triazine ring at the end of the linker section. These modified dyes then were reacted with cellulose nanocrystals in acetonitrile at elevated temperature, again isolating material with the characteristic spectral bands of the Alexa Fluor dye. Reactions with Alexa Fluor 546 are given as detailed examples, labeling on the order of 1% of the total glucopyranose rings of the cellulose nanocrystals at dye loadings of ca. 5 µg/mg cellulose. Fluorescent cellulose nanocrystals were deposited in pore network microfluidic structures (PDMS) and proof-of-principle bioimaging experiments showed that the spatial localization of the solid cellulose deposits could be determined, and their disappearance under the action of Celluclast enzymes or microbes could be observed over time. In addition, single molecule fluorescence microscopy was demonstrated as a method to follow the disappearance of solid cellulose deposits over time, following the decrease in the number of single blinking dye molecules with time instead of fluorescent intensity.

Catalytic templating approaches for three-dimensional hollow carbon/graphene oxide nano-architectures.

We report a catalytic templating method to synthesize well-controlled three-dimensional carbon nano-architectures. Depending on graphene oxide content, the morphology can be systematically tuned from layered composites to 3D hollow structures to microporous materials. The composites with high surface area and high porosity induce a significant enhancement to its capacitance at high current density.