Simple Surface Research Articles

Robust, Flexible, and High-Barrier Films from Bacterial Cellulose Modified by Long-Chain Alkenyl Succinic Anhydrides

This paper describes a simple and low-pollution surface modification strategy for fabricating flexible, semi-transparent, and robust bacterial cellulose (BC)/Kombucha tea-based BC films that are effectively resistant to water, water vapor, oxygen, ultraviolet light, and foodborne pathogenic bacteria. The strategy uses dimethyl sulfoxide as the pre-swelling solvent and long-chain alkenyl succinic anhydrides with different chain lengths as the esterifying agents. The proof of esterification, crystallinity index, film microstructure, and degree of surface substitution were systematically investigated. Our result showed that acylation with 2-octenylsuccinic anhydride for 8 h conferred the BC films with the highest water-vapor/oxygen resistance and optimal mechanical/thermal properties. In addition, the modified BC film has good antimicrobial properties and is capable of wrapping strawberries, increasing their longevity. Biodegradation and alkaline hydrolysis tests demonstrated that compostability of the film and recycling of the BC pulp are possible, revealing that such high-performance biofilm-based food packaging could have a green life cycle.

Simultaneous deposition of tannic acid derivative and covalent conjugation of poly(2-methyl-2-oxazoline) for the construction of antifouling coatings

Bacterial adhesion and subsequent colonization play an important role in the failure of biomedical implants and devices. Thus, development of a simple surface modification strategy to combat bacterial adhesion is highly desirable. In this work, “one-pot” fabrication of antifouling coatings based on simultaneous surface adhesion of trihydroxyphenyl and dihydroxyphenyl moieties of tannic acid (TA) derivative and covalent conjugation of hydrophilic poly(2-methyl-2-oxazoline) (PMOXA) was demonstrated. Surface co-depositions of TA/PMOXA hybrids of different TA derivative to PMOXA weight ratios and different molecular weights of PMOXA were conducted. The surface hydrophilicity and deposition universality on various substrates were investigated. The anti-bacterial and anti-platelet adhesion, as well as anti-biofilm formation abilities, of the TA/PMOXA-based coating were also studied. In vitro hemolysis and cytotoxicity, and in vivo biocompatibility of the TA/PMOXA-based coating were further evaluated. All the results indicate that the TA/PMOXA-based coating could be employed as an antifouling additive on biomedical implants and devices.

Properties of minimal charts and their applications IX: charts of type [formula omitted

Charts are oriented labeled graphs in a disk. Any simple surface braid (2-dimensional braid) can be described by using a chart. Also, a chart represents an oriented closed surface embedded in 4-space. In this paper, we investigate embedded surfaces in 4-space by using charts. Let Γ be a chart, and we denote by Γm the union of all the edges of label m. A chart Γ is of type (4,3) if there exists a label m such that w(Γ)=7, w(Γm∩Γm+1)=4, w(Γm+1∩Γm+2)=3 where w(G) is the number of white vertices in G. In this paper, we prove that there is no minimal chart of type (4,3).

STUDY OF OCULAR TRAUMA - FOREIGN BODY IMPACTION AND LID LACERATION, REPAIRED THROUGH TENZEL SEMICIRCULAR FLAP

background- Ocular trauma is a worldwide cause of visual morbidity , which occurs in RTA and includes a spectrum of simple ocular surface or intraocular foreign bodies, abrasions to devastating lid and ocular injuries.method- prospective interventional study of an individual with 60% tissue loss in lower lid and intraocular fb embedded in deep palpebral conjunctiva.result- early intervention ,identication and removal of foreign body involved early visual recovery and immediate lid laceration repair with relaxing incision and ap reconstruction in better cosmesis and complication prevention.

An Overview on Gold Nanorods as Versatile Nanoparticles in Cancer Therapy.

Gold nanorods (GNRs/AuNRs) are a group of gold nanoparticles which their simple surface chemistry allows for various surface modifications, providing the possibility of using them in the fabrication of biocompatible and functional nano-agents for cancer therapy. AuNRs, moreover, exhibit a maximum absorption of longitudinal localized surface plasmon resonance (LSPR) in the near-infrared (NIR) region which overlaps with NIR bio-tissue 'window' suggesting that they are proper tools for thermal ablation of cancer cells. AuNRs can be used for induction of mono or combination therapies by administering various therapeutic approaches such as photothermal therapy (PTT), photodynamic therapy (PDT), chemotherapy (CT), radiotherapy (RT), and gene therapy (GT). In this review, anticancer therapeutic capacities of AuNRs along with different surface modifications are summarized comprehensively. The roles of AuNRs in fabrication of various nano-constructs are also discussed.

Superhydrophilic and topography-regulatable surface grafting on PEEK to improve cellular affinity

Polyetheretherketone (PEEK) has been widely used in the preparation of orthopedic implants due to its biological inertness and similar mechanical modulus to natural bone. However, the affinity between biological tissue (bone and soft tissue) and PEEK surface is weak, leading to low osseointegration and an increased risk of inflammation. The situation could be improved by modifying PEEK surface. Surfaces with good hydrophilicity and proper microtopography would promote cellular adhesion and proliferation. This work presented a two-step surface modification method to achieve the effect. Polyacrylic acid (PAA) chains were grafted on PEEK surface by UV irradiation. Then, ethylenediamine (EDA) was added to introduce amino groups and promote the cross-linking of PAA chains. Furthermore, a mathematical model was built to describe and regulate the surface topography growth process semi-quantitatively. The model fits experimental data quite well (adjusted R2 = 0.779). Results showed that the modified PEEK surface obtained superhydrophilicity. It significantly improved the adhesion and proliferation of BMSCs and MFBs by activating the FAK pathway and Rho family GTPase. The cellular affinity performed better when the surface topography was in network structure with holes in about 25 μm depth and 20–50 μm diameter. Good hydrophilicity seems necessary for the FAK pathway activation, but simply improving surface hydrophilicity might not be enough for cellular affinity improvement. Surface topography at micron scale should be a more important cue. This simple surface modification method could be contributed to further study of cell-microtopography interaction and have potential applications in clinical PEEK orthopedic implants.

Fast spin-echo approach for accelerated B1 gradient-based MRI.

To expand on the previously developed -encoding technique, frequency-modulated Rabi-encoded echoes (FREE), to perform accelerated image acquisition by collecting multiple lines of k-space in an echo train. FREE uses adiabatic full-passage pulses and a spatially varying RF field to encode unique spatial information without the use of traditional B0 gradients. The original implementation relied on acquiring single lines of k-space, leading to long acquisitions. In this work, an acceleration scheme is presented in which multiple echoes are acquired in a single shot, analogous to conventional fast spin-echo sequences. Theoretical analysis and computer simulations investigated the feasibility of this approach and presented a framework to analyze important imaging parameters of FREE-based sequences. Experimentally, the multi-echo approach was compared with conventional phase-encoded images of the human visual cortex using a simple surface transceiver coil. Finally, different contrasts demonstrated the clinical versatility of the new accelerated sequence. Images were acquired with an acceleration factor of 3.9, compared with the previous implementation of FREE, without exceeding specific absorption rate limits. Different contrasts can easily be acquired without major modifications, including inversion recovery-type images. FREE initially illustrated the feasibility of performing slice-selective 2D imaging of the human brain without the need for a B0 gradient along the y-direction. The multi-echo version maintains the advantages that encoding provides but represents an important step toward improving the clinical feasibility of such sequences. Additional acceleration and more advanced reconstruction techniques could further improve the clinical viability of FREE-based techniques.

Mechanical Reinforcement of Thermoplastic Polyurethane Nanocomposites by Surface‐Modified Nanocellulose

AbstractUtilization of biodegradable nanofillers is an emerging approach for the sustainable development of polymer composites. Among numerous green nanofillers, nanocellulose has garnered significant attention because of its abundance, high mechanical strength, and reinforcing capability. However, the intrinsic hydrophilicity of nanocellulose often restricts its homogeneous dispersion in the hydrophobic polymer matrix, resulting in a poor reinforcement effect. In this study, a simple surface modification of cellulose nanofibrils (CNFs) using small hydrophobic molecules is presented. Hydrophobic‐modified CNFs have better solubility in organic solvents and exhibit homogeneous dispersion in a thermoplastic polyurethane (TPU) matrix. The molecular interaction between CNFs and the hard/soft segments (HS/SS) of TPU induces surface‐mediated crystallization with improved microphase separation of SS and HS. By bridging multiple HS and SS microdomains, hydrophobic‐modified CNFs improve the tensile modulus and ultimate tensile strength of the polymer nanocomposites. On the other hand, unmodified CNFs are strongly aggregated in the TPU matrix, which restricts the mechanical reinforcement. These results demonstrate that surface modification of nanocelluloses can engineer their dispersion state and interfacial interaction with matrix polymers, which are crucial for the mechanical reinforcement of polymer nanocomposites.

Surface Stoichiometry Control of Colloidal Heterostructured Quantum Dots for High-Performance Photoelectrochemical Hydrogen Generation.

Manipulating the separation and transfer behaviors of charges has long been pursued for promoting the photoelectrochemical (PEC) hydrogen generation based on II-VI quantum dot (QDs), but remains challenging due to the lack of effective strategies. Herein, a facile strategy is reported to regulate the recombination and transfer of interfacial charges through tuning the surface stoichiometry of heterostructured QDs. Using this method, it is demonstrated that the PEC cells based on CdSe-(Sex S1- x )4 -(CdS)2 core/shell QDs with a proper Ssurface /Cdsurface ratio exhibits a remarkably improved photocurrent density (≈18.4mA cm-2 under one sun illumination), superior to the PEC cells based on QDs with Cd-rich or excessive S-rich surface. In-depth electrochemical and spectroscopic characterizations reveal the critical role (hole traps) of surface S atoms in suppressing the recombination of photogenerated charges, and further attribute the inferior performance of excessive S-rich QDs to the impeded charge transfer from QDs to TiO2 and electrolyte. This work puts forward a simple surface engineering strategy for improving the performance of QDs PEC cells, providing an efficient method to guide the surface design of QDs for their applications in other optoelectronic devices.

Adsorbed p-Aminothiophenol Molecules on Platinum Nanoparticles Improve Electrocatalytic Hydrogen Evolution.

Electrocatalytic hydrogen evolution is an important approach to produce clean energy, and many electrocatalysts (e.g., platinum) are developed for hydrogen production. However, the electrocatalytic efficiency of commonly used metal catalysts needs to be improved to compensate their high cost. Herein, the electrocatalytic efficiency of platinum nanoparticles (PtNPs) in hydrogen evolution is largely improved via simple surface adsorption of sub-monolayer p-aminothiophenol (PATP) molecules. The overpotential goes down to 86.1mV, which is 50.2mV lower than that on naked PtNPs. This catalytic activity is even better than that of 20wt.% Pt/C, despite the much smaller active surface area of PATP-adsorbed PtNPs than Pt/C. It is theoretically and experimentally confirmed that the improved electrocatalytic activity in hydrogen evolution can be attributed to the change in electronic structure of PtNPs induced by surface adsorption of PATP molecules. More importantly, this strategy can also be used to improve the electrocatalytic activity of palladium, gold, and silver nanoparticles. Therefore, this work provides a simple, convenient, and versatile method for improving the electrocatalytic activity of metal nanocatalysts. This surface adsorption strategy may also be used for improving the efficiency of many other nanocatalysts in many reactions.

Zeolites as multifunctional additives stabilize high-voltage Li-batteries based on LiNi0.5Mn1.5O4 cathodes, mechanistic studies

The work reported herein discusses the improved electrochemical and thermal behavior of LiNi0.5Mn1.5O4 (LNMO) spinel cathodes via surface engineering using a series of zeolites. The limiting issues of these high voltage electrodes are phase transition during Li-ions intercalation/de-intercalation processes, weakening the active material's structure. Besides, it initiates harmful interfacial side reactions, including solution species oxidation and Ni & Mn dissolution, affecting their long-term cycling stability severely and detrimentally. Therefore, we propose a zeolite-based surface modification of LNMO involving a simple surface coating strategy that includes liquid-phase (ethanol) mixing followed by heat treatment at 200 °C under nitrogen gas flow. The cathodes comprising LNMO coated with 2 wt% zeolites exhibited significantly improved cycling stability than the reference cathodes with the uncoated material. Furthermore, we discovered that the zeolite species adsorbed to the LNMO surface act as buffer interphase that enhance the electrodes' redox kinetics, trapping dissolved-TMs ions and serving as local Li+-ions reservoirs. Pouch cells containing graphite anodes and zeolite-coated LNMO cathodes demonstrated impressively improved electrochemical behavior in capacity retention during prolonged cycling, enhanced rate capability, lower voltage hysteresis, and direct current internal resistance (DCIR) evolution. The zeolite-based surface coating participates in (i) lowering HF formation in battery solutions by absorbing trace water, (ii) HF scavenging, and (iii) lowering TMs cations dissolution. Furthermore, Si and Al constituents of the zeolites can deposit on Li-anodes and possibly increase their stability, later established by additional electrochemical studies of full-pouch cells comprising uncoated LNMO cathodes vs. zeolite-coated graphite anodes. Other pivotal findings of this work are the coherent structural, morphological, and thermal stabilization of zeolite-coated LNMO cathodes during prolonged cycling experiments.

Theoretical superlubricity and its friction stability of amorphous carbon film induced by simple surface graphitization

Amorphous carbon (a-C) film as one of the most promising superlubricious materials arouses much attention from technical and industrial fields. However, the superlubricious state of a-C film strongly depends on the formation of special nanostructures or components, increasing the difficulty and complexity of the preparation process. Reducing the friction coefficient of a-C film to superlubricity is still a challenge for industrial scale-up. Herein, a simple and effective approach is proposed to achieve superlubricity by in-situ formation of graphitized structure at a-C surface via fast annealing. Results reveal that the friction property closely depends on the graphitized degree of mated a-C surfaces and the friction coefficient below 0.01 or even 0.001 can be obtained for the highly graphitized system. In particular, under extreme working condition, it also demonstrates excellent stability and reliability of superlubricious behavior. This is not only mainly attributed to the decrease of spacing distance between mated graphitized structures following the high repulsive force, but also related to the tight anchoring of graphitized structure to the intrinsic a-C. In addition, compared to the widely applied surface passivation approach, the graphitization modification of a-C surface exhibits higher effectiveness in superlubricity without deteriorating the intrinsic mechanical properties of a-C film.

Photophysics of the red-form Kaede chromophore.

The green fluorescent protein (GFP) drove revolutionary progress in bioimaging. Photoconvertible fluorescent proteins (PCFPs) are an important branch of the FP family, of which Kaede is the prototype. Uniquely, PCFPs can be permanently switched from green to red emitting forms on UV irradiation, facilitating applications in site-specific photolabelling and protein tracking. Optimisation and exploitation of FPs requires understanding of the photophysical and photochemical behaviour of the chromophore. Accordingly, the principal GFP chromophore has been the subject of intense experimental and theoretical investigation. In contrast, the photophysics of the red emitting PCFP chromophore are largely unstudied. Here we present a detailed investigation of the excited-state properties of the Kaede chromophore in solution, utilising steady state measurements, ultrafast time-resolved electronic and vibrational spectroscopies, and electronic structure theory. Its excited state dynamics are very different to those of the parent GFP. Most remarkably, the PCFP chromophore has highly complex wavelength-dependent fluorescence decays and a mean lifetime an order of magnitude longer than the GFP chromophore. Transient electronic and vibrational spectroscopies suggest that these dynamics arise from a range of excited-state conformers that are spectrally and kinetically distinct but chemically similar. These conformers are populated directly by excitation of a broad thermal distribution of ground state structures about a single conformer, suggesting an excited-state potential surface with several minima. Temperature-dependence confirms the existence of barriers on the excited-state surface and reveals the radiationless decay mechanism to be internal conversion. These experimental observations are consistent with a model assuming a simple ground state potential energy surface accessing a complex excited state possessing multiple minima.

Highly sensitive surface acoustic wave biosensor for the detection of Hg2+ based on the thymine-Hg2+-thymine structure.

The detection of mercury ions (Hg2+) with an ultralow concentration is of great significance for the treatment of heavy metal pollution in industrial waste water and the monitoring of drinking water quality. In this study, a simple, sensitive, and portable surface acoustic wave (SAW) biosensor for the determination of Hg2+ concentration was developed. First, a DNA fragment with a specific binding capacity for Hg2+ was chemically adsorbed on to the sensitive region through forming Au-S bonds with the SAW biosensor. The DNA probe could then form a thymine-Hg2+-thymine (T-Hg2+-T) complex with strong affinity for Hg2+ after immersion in a test solution containing Hg2+, resulting in a significant change in the response frequency of the device. The linear detection range of the device was 10 pM to 1 nM, while the limit of detection (LOD) was as low as 6.3 pM. Furthermore, the SAW biosensor exhibited excellent selectivity to Hg2+ compared with that of interfering ions, e.g., Ag+, Ba2+, Cu2+, Zn2+, Mn2+, Fe3+, Ca2+, and Na+. The results provide a new strategy for the preparation of portable devices that can monitor toxic heavy metal ions with high sensitivity and selectivity.

Efficient electrocatalytic oxygen reduction reaction of thermally optimized carbon black supported zeolitic imidazolate framework nanocrystals under low-temperature.

Turning commercially available low-cost conducting carbon black materials into functional electrocatalytic electrode media using simple surface chemical modification is a highly attractive approach. This study reports on remarkably enhanced oxygen electrocatalytic activity of commercially available Ketjenblack (KB) by growing a non-precious cobalt metal-based zeolitic-imidazolate framework (ZIF-67) at room temperature in methanol solution followed by a mild thermolysis. The resulting Co@CoOx nanoparticle decorated nitrogen-doped KB derived from the optimized ZIF-67 : KB weight ratio of hybrid samples at 500-600 °C shows high performance for the oxygen reduction reaction (ORR) with impressive Eonset and E1/2 values of ∼0.90 and ∼0.83 V (vs. RHE), respectively in 0.1 M KOH electrolyte. Such ORR activity is comparable to, or better than many metal@metal-oxide-carbon based electrocatalysts synthesized under elevated carbothermal temperatures and using multicomponent/multistep chemical modification conditions. Therefore, a simple electrocatalyst design reported in this work is an efficient synthesis route that not only utilises earth-abundant carbon black but also comprises scalable room temperature synthesized ZIF-67 following mild thermolysis conditions under 600 °C.

Design of carbon dots as nanozymes to mediate redox biological processes.

Nanozymes are a new type of artificial enzyme based on engineered nanomaterials, developed to help understand and mimic natural enzymes in order to make better catalytic materials, understand the structure-function relationship and utilize the unique properties of artificial nanozymes. Carbon dot (CD)-based nanozymes have attracted great attention due to their biocompatibility, high catalytic activity and simple surface functionalization, and have shown great potential in biomedical and environmental applications. In this review, we propose a possible precursor selection method to synthesize CD nanozymes with enzyme-like activities. Doping or surface modification methods are introduced as effective strategies to enhance the catalytic performance of CD nanozymes. Recently, CD-based single-atom nanozymes and hybrid nanozymes have been reported, which bring a new perspective to the research of nanozymes. Finally, the challenges of CD nanozymes in clinical transformations are discussed, and the research direction is proposed. The latest research progress and application of CD nanozymes in mediating redox biological processes are summarized in order to further explore the potential of carbon dots in biological therapy. We also provide more ideas for researchers who focus on the design of nanomaterials with antibacterial, anti-cancer, anti-inflammatory, antioxidant and other functions.

Comparison of Complex and Simple Anthropometrics in the Descriptive Anthropometric Assessment of Male Cyclists

Introduction: Compare the importance of complex (areas and volumes) and simple (lengths and girths) surface anthropometrics in the descriptive anthropometric assessment of the lower body of male cyclists from different disciplines. Method: Using a 3dMDBody5 3D surface imaging system and bespoke software (KinAnthroScan), anthropometrics of the lower body of 23 male non-cyclists and 57 elite male cyclists from different cycling disciplines: sprint (track and road (hill)), endurance (road, > 50 miles), time trial (road, < 50 miles) and mountain bike (cross-country and enduro) were collected. Results: Several anthropometrics differed between cycling groups and when compared to the non-cyclists group; the sprint group demonstrated the largest magnitude of difference with other cycling disciplines and the non-cyclists group, whereas the time trial and mountain bike groups demonstrated the least. Complex anthropometrics were able to distinguish between groups as effectively as simple anthropometrics, and in some cases, were able to distinguish differences that were unidentifiable through simple anthropometrics alone. Conclusions: Researchers, anthropometrists and practitioners should consider the collection and use of complex anthropometrics to improve the understanding of anthropometric differences within descriptive anthropometry, alongside adopting caution when researching groups of cyclists from different disciplines due to their differing anthropometric profiles - categorising them by discipline when possible.

A Comparison between Various Polymeric Membranes for Oily Wastewater Treatment via Membrane Distillation Process.

Oily wastewater (OW) is detrimental towards the environment and human health. The complex composition of OW needs an advanced treatment, such as membrane technology. Membrane distillation (MD) gives the highest rejection percentage of pollutants in wastewater, as the membrane only allows the vapor to pass its microporous membrane. However, the commercial membranes on the market are less efficient in treating OW, as they are prone to fouling. Thus, the best membrane must be identified to treat OW effectively. This study tested and compared the separation performance of different membranes, comparing the pressure-driven performance between the membrane filtration and MD. In this study, several ultrafiltration (UF) and nanofiltration (NF) membranes (NFS, NFX, XT, MT, GC and FILMTEC) were tested for their performance in treating OW (100 ppm). The XT and MT membranes (UF membrane) with contact angles of 70.4 ± 0.2° and 69.6 ± 0.26°, respectively, showed the best performance with high flux and oil removal rate. The two membranes were then tested for long-term performance for two hours with 5000 ppm oil concentration using membrane pressure-filtration and MD. The XT membrane displayed a better oil removal percentage of >99%. MD demonstrated a better removal percentage; the flux reduction was high, with average flux reduction of 82% compared to the membrane pressure-filtration method, which experienced a lower flux reduction of 25%. The hydrophilic MT and XT membranes have the tendency to overcome fouling in both methods. However, for the MD method, wetting occurred due to the feed penetrating the membrane pores, causing flux reduction. Therefore, it is important to identify the performance and characteristics of the prepared membrane, including the best membrane treatment method. To ensure that the MD membrane has good anti-fouling and anti-wetting properties, a simple and reliable membrane surface modification technique is required to be explored. The modified dual layer membrane with hydrophobic/hydrophilic properties is expected to produce effective separation in MD for future study.

Advanced Nanomaterials for the Diagnosis and Treatment of Renal Cell Carcinoma

Renal cell carcinoma (RCC) is the most common type of kidney cancer. Owing to the high morbidity rate of RCC, there is an urgent need for intensive research on robust materials to diagnose and treat RCC. Nanomaterials have been developed largely in the last three decades because of their numerous advantages, such as high specific surface area, simple surface functionalization, rapid onset of therapeutic action, superior biological activity, and other unique physical–chemical characteristics. Herein, first, various types of nanomaterials used in RCC treatment are introduced, including inorganic nanomaterials, lipid nanomaterials, synthetic polymer nanomaterials, and natural nanomaterials. Second, the different diagnosis and therapeutic mechanisms of nanomaterials in the kidneys are reviewed and these advantages of nanomaterials are highlighted. Furthermore, nanomaterials are investigated for the preclinical and clinical detection and treatment of RCC. Finally, the challenges and outlook of various nanomaterials for RCC diagnostic and treatment are discussed.

The -isomorphism property for a class of singularly-weighted x-ray transforms

We study a one-parameter family of self-adjoint normal operators for the x-ray transform on the closed Euclidean disk , obtained by considering specific singularly weighted L 2 topologies. We first recover the well-known singular value decompositions in terms of orthogonal disk (or generalized Zernike) polynomials, then prove that each such realization is an isomorphism of . As corollaries: we give some range characterizations; we show how such choices of normal operators can be expressed as functions of two distinguished differential operators. We also show that the isomorphism property also holds on a class of constant-curvature, circularly symmetric simple surfaces. These results allow to design functional contexts where normal operators built out of the x-ray transform are provably invertible, in Fréchet and Hilbert spaces encoding specific boundary behavior.