A novel approach to composite preparation by direct synthesis of carbon nanomaterial on matrix or filler particles

Carbon nanotubes (CNTs), nanofibers (CNFs) and graphene are promising components for next-generation high-performance structural and multifunctional composite materials. One of the largest obstacles to creating strong, electrically or thermally conductive CNT/CNF or graphene composites is the difficulty of achieving a good dispersion of the carbon nanomaterials in a matrix. Typically, time-consuming steps of carbon nanomaterial purification, ultrasound treatment and functionalization are required. We utilized a novel approach to fabricate composite materials by growing CNTs/CNFs directly on the surface of matrix, matrix precursor or filler particles. As the precursor matrix and fillers we utilized cement (clinker), copper powder, fly ash particles, calcinated soil and sand. Carbon nanomaterials were successfully grown on these materials without additional catalyst. Investigations of the physical properties of the composite materials based on these carbon-modified particles revealed enhanced mechanical and electrical properties. The improvement in the mechanical properties of the C/Cu-based composite materials is attributed the crystallite or grain formation of the matrix material.     

Development of xMAP Assay for Detection of Six Protein Toxins

xMAP technology was used for simultaneous identification of six protein toxins (staphylococcal enterotoxins A and B, cholera toxin, ricin, botulinum toxin A, and heat labile toxin of E. coli). Monoclonal antibody-conjugated xMAP microspheres and biotinilated monoclonal antibodies were used to detect the toxins in a sandwich immunoassay format. The detection limits were found to be 0.01 ng/mL for staphylococcal enterotoxin A, cholera toxin, botulinum toxin A, and ricin in model buffer (PBS-BSA) and 0.1 ng/mL for staphylococcal enterotoxin B and LT. In a complex matrix, such as cow milk, the limits of detection for staphylococcal enterotoxins A and B, cholera toxin, botulinum toxin A, and ricin increased 2- to 5-fold, while for LT the detection limit increased 30-fold in comparison with the same analysis in PBS-BSA. In the both PBS-BSA and milk samples, the xMAP test system was 3-200 times (depending on the toxin) more sensitive than ELISA systems with the same pairs of monoclonal antibodies used. The time required for a simultaneous analysis of six toxins using the xMAP system did not exceed the time required for ELISA to analyze one toxin. In the future, the assay may be used in clinical diagnostics and for food and environmental monitoring.     

Nucleation of methane hydrate and ice in emulsions of water in crude oils and decane under non-isothermal conditions

Achievable supercooling for the formation of methane hydrate from water emulsions was studied in seven different crude oils and in decane. The experiments were performed under constant rate cooling from + 20 to-15 °C and a pressure of methane of 12 MPa. It was demonstrated that the shapes and positions of the resulting survival curves depend on the density, viscosity and dispersive power of oil samples used in the experiments, as well as on the degree of oil oxidation. In addition, results of the experiments on ice freezing under the same emulsions are presented. The results obtained in the work allowed us to discuss the possibility and features of primary and secondary nucleation of the hydrate and ice in the systems under consideration.     

Swelling Behavior and Complex Formation Ability of Ternary Amphoteric Gels based on Allylamine Derivatives and Maleic Acid

Summary: The swelling behavior of an amphoteric gel composed of 50 mol‐% of maleic acid (MA), 25 mol‐% of N,N′‐dimethyldiallylammonium chloride (DMDAAC) and 25 mol‐% of diallylamine (DAA) was studied in aqueous and aqueous‐salt solutions. The isoelectric point (IEP) of the MA‐DMDAAC‐DAA gel determined from swelling experiments was about pH 4.6. Considerable gel swelling with increasing ionic strength was observed at the IEP. Dynamic swelling properties of the amphoteric gel in water with and without added salt were measured at various pH values including the IEP. The swelling behavior of the amphoteric gel was found to depend on the ionization state of the functional groups. It can be described by either a relaxation‐controlled or non‐Fickian (anomalous) mechanism. Swelling‐deswelling properties of the amphoteric gel were also studied in mixtures of water and organic solvents. The amphoteric gel was able to complex sodium poly(styrene sulfonate), sodium lauryl sulfate, the cationic drug richlocain, and the bivalent transition metal ions Cu²⁺, Ni²⁺, Co²⁺, and Zn²⁺. The sorption of polyelectrolyte, surfactant, drug, and metal ions by the amphoteric gel is accompanied by the contraction of the gel network. Partial release of the cationic drug molecules entrapped into the gel volume takes place at the IEP of the amphoteric gel with low activation energy, while neither the anionic polyelectrolyte nor the surfactants are released from the gel interior at the IEP. The swelling‐shrinking behavior of gel‐polyelectrolyte and gel‐surfactant complexes in dependence of pH and ionic strength of the outer solution is similar.

     

Marine Two-Headed Sphingolipid-Like Compound Rhizochalin Inhibits EGF-Induced Transformation of JB6 P<Superscript>+</Superscript> Cl41 Cells

Rhizochalin [(2R,3R,26R,27R)-2,27-diamino-3-hydroxy-26-[(2R,3R,4S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yloxy]octacosan-11-one], an antimicrobial and cytotoxic marine two-headed sphingolipid-like natural product, isolated from the sponge Rhizochalina incrustata, and some related compounds were studied as anticarcinogenic and proapoptotic agents. The corresponding effects were tested on the mouse skin epidermal JB6 P⁺ Cl 41 cell line, its stable transfectants, THP-1, HeLa, and SNU-C4 human tumor cells using a variety of assessments, including cell viability (MTS), flow cytometry, anchorage-independent soft agar, and luciferase assays. At 5–10 μM concentrations, rhizochalin was effective as an inhibitor of the malignant transformation of JB6 P⁺ Cl 41 cells or colony formation of human tumor cells, which exerted its action, at least in part, through the induction of p53-dependent apoptosis. Structure–activity relationship study showed aglycon of rhizochalin to be the most active while peracetylated aglycon was the least active among the compounds studied.     

Cytotoxic Activity of LLO Y406A Is Targeted to the Plasma Membrane of Cancer Urothelial Cells

Identification of novel agents for bladder cancer treatment is highly desirable due to the high incidence of tumor recurrence and the risk of progression to muscle-invasive disease. The key feature of the cholesterol-dependent toxin listeriolysin O mutant (LLO Y406A) is its preferential activity at pH 5.7, which could be exploited either directly for selective targeting of cancer cells or the release of accumulated therapeutics from acidic endosomes. Therefore, our goal was to compare the cytotoxic effect of LLO Y406A on cancer cells (RT4) and normal urothelial cells (NPU), and to identify which cell membranes are the primary target of LLO Y406A by viability assays, life-cell imaging, fluorescence, and electron microscopy. LLO Y406A decreased viability, altered cell morphology, provoked membrane blebbing, and induced apoptosis in RT4 cells, while it did not affect NPU cells. LLO Y406A did not cause endosomal escape in RT4 cells, while the plasma membrane of RT4 cells was revealed as the primary target of LLO Y406A. It has been concluded that LLO Y406A has the ability to selectively eliminate cancer urothelial cells through pore-forming activity at the plasma membrane, without cytotoxic effects on normal urothelial cells. This promising selective activity merits further testing as an anti-cancer agent.     

Improved Maxwell Model Approach and its Applicability toward Lifetime Prediction of Biobased Viscoelastic Fibers

The evaluation of relaxation measurements is a well-established technique for predicting the lifetime of polymer materials, with research primarily focusing on increasing prediction accuracy and minimizing material testing time. The current study presents a novel approach toward describing the long-term behavior of viscoelastic polymers based on the Maxwell model. It assumes a mean relaxation time of the polymer chains in conjunction with a dimensionless number that accounts for averaged polymer chain inhomogeneities. This coefficient is analogous to the dimensionless number, which successfully describes the asymmetry of both the Weibull distribution and of particle size distribution according to the Rosin, Rammler, Sperling and Bennet model. In comparison to earlier models based on time-superposition principles, the current approach enables lifetime prediction using a single short-term measurement, which must be taken at a properly chosen applied strain. The applicability of the new model in predicting the long-term behavior has been demonstrated by the analysis of the relaxation behavior of semi-crystalline bio-based fibers.     

Amorphous silica wastes for reusing in highly porous ceramics

The paper analyzes a solution in green manufacturing of foamed or cellular ceramics. The objective of this study was to determine the technical solution for rice husk ash and “tales” of mixed glass cullet reusing based on the specific properties of these materials for creation of spherical holes inside ceramic using the process of coalescence of cellular glass. The paper reports on experimental results obtained from the production of lightweight cellular glass granules produced using glass cullet and rice husk ash. Lightweight cellular glass granules were mixed with clay, pressed and fired in air at 920°C. Clay sintering and the formation of ceramic were followed with the coalescence of cellular structure of glass granules and with the formation of spherical hollows inside the matrix. Density and strength of the fired ceramic bodies were determined. It is observed that the lightweight ceramics with density 900 ÷ 920 kg/m³ possess a compressive strength of about 5 MPa that is acceptable for bricks or tiles manufacture. The utilization of amorphous silica waste for lightweight ceramics manufacture helps in reducing waste disposal concerns and costs associated, and also transforms the waste into an alternative raw material with added value, moreover making the final product cheap.     

Design strategies for materials showing thermally activated delayed fluorescence and beyond: Towards the fourth‐generation OLED mechanism

Design strategies for molecules showing thermally activated delayed fluorescence (TADF) are discussed, and a new emitter concept based on an almost “zero‐energy‐gap” is developed. Thermal activation is not substantial. Applied in an organic light emitting diode, all singlet and triplet excitons are harvested directly in the lowest singlet state without time‐delaying TADF. This landmarking mechanism, being beyond TADF, leads to emission decay times in the sub‐μs range.