Synthesis of layered zinc hydroxide intercalated with dodecyl sulfate organic–inorganic hybrid nanocomposite as a fiber coating for the headspace solid‐phase microextraction of aromatic hydrocarbons from water

We describe the synthesis of a layered zinc hydroxide‐dodecyl sulfate organic–inorganic hybrid nanocomposite as a new solid‐phase microextraction fiber. The fiber coating can be prepared easily in a short time and the reaction is at room temperature; it is mechanically stable and exhibits relatively high thermal stability. The synthesized layered zinc hydroxide‐dodecyl sulfate nanocomposite was successfully prepared and immobilized on a stainless steel wire and evaluated for the extraction of aromatic compounds from aqueous sample solutions in combination with gas chromatography and mass spectrometry. The method yields good results for some validation parameters. Under optimum conditions (extraction time: 15 min, extraction temperature: 50°C, desorption time: 1 min, desorption temperature: 250°C, salt concentration: 0.5 g/mL), the limit of detection and dynamic linear range were 0.69–3.2 ng/L and 10–500 ng/L, respectively. The method was applied to the analyses of benzene, toluene, ethylbenzene, and o‐, p‐, and m‐xylenes in two real water samples collected from the Aji river and Mehran river, Tabriz, Iran. Under optimum conditions, the repeatability and reproducibility for one fiber (n = 3), expressed as the relative standard deviation, was 3.2–7.3% and 4.2–11.2% respectively. The fibers are thermally stable and yield better recoveries than conventional methods of analysis.     

Response surface analysis for understanding the effects of synthesis parameters on the microstructure of hyperbranched polyesters

Synthesis parameters including the time of condensation reaction, the monomer-to-core ratio (2, 2-bis (hydroxymethyl) propionic acid) (pseudo-generation) and the type of catalyst were changed methodically to investigate their effects on the microstructure of resulting hyperbranched polyesters (HBPEs). Response surface methodology (RSM) was utilized to uncover the relationship between changing variables and the number of terminal hydroxyl groups of HBPSs by which the individual and interactive effects of the aforementioned synthesis parameters were explored. The degree of branching and molecular weight of the HBPEs were evaluated by titration of hydroxyl number and gel permeation chromatography, respectively. Fourier transform infrared spectroscopy and nuclear magnetic resonance analyses confirmed attachment of functional groups to the molecules. Interpretations based on RSM showed that increase of the number of the core molecules, which is equivalent To reduction of the pseudo-generation, narrows the molecular weight distribution of the prepared hyperbranched polyester; so that the lowest molecular weight distribution is obtained for the first pseudo-generation HBPEs with the monomer-to-core ratio of 3:1 and the average number of the terminal hydroxyl groups in between 6 and 8. The samples prepared by the sulfuric acid catalyst had the highest average number of terminal hydroxyl groups, at the same time narrowest molecular weight distribution.     

A simple and rapid flow-injection chemiluminescence method for the determination of noscapine with Ru(phen)3(2+)-Ce(IV) system

A new flow injection chemiluminescence (CL) system was used for the determination of noscapine. This technique is based on the reduction effect of noscapine on the Ru(phen)3(3+), which is produced by reaction between Ru(phen)3(2+) and acidic Ce(IV) solutions, and this rapid reduction produces strong CL. Calibration plots were linear over the range of 3.0 x 10(-7) - 2.0 x 10(-6) mol L(-1) and 2.0 x 10(-6) - 2.0 x 10(-4) mol L(-1). The CL intensity was so high, that it is able to produce a detection limit of 6.6 x 10(-8) M noscapine (3sigma). The relative standard deviation of 2.0 x 10(-6) M noscapine was 1.0% (n=10). The proposed method was successfully applied for the flow injection determination of noscapine in cough and Tonin syrup samples. The results of real sample analyses show good recovery percentages (97.3-102.4%). The minimum sampling rate was 100 samples per hour.     

From Oncogenic Signaling Pathways to Single-Cell Sequencing of Immune Cells: Changing the Landscape of Cancer Immunotherapy

Over the past decade, there have been remarkable advances in understanding the signaling pathways involved in cancer development. It is well-established that cancer is caused by the dysregulation of cellular pathways involved in proliferation, cell cycle, apoptosis, cell metabolism, migration, cell polarity, and differentiation. Besides, growing evidence indicates that extracellular matrix signaling, cell surface proteoglycans, and angiogenesis can contribute to cancer development. Given the genetic instability and vast intra-tumoral heterogeneity revealed by the single-cell sequencing of tumoral cells, the current approaches cannot eliminate the mutating cancer cells. Besides, the polyclonal expansion of tumor-infiltrated lymphocytes in response to tumoral neoantigens cannot elicit anti-tumoral immune responses due to the immunosuppressive tumor microenvironment. Nevertheless, the data from the single-cell sequencing of immune cells can provide valuable insights regarding the expression of inhibitory immune checkpoints/related signaling factors in immune cells, which can be used to select immune checkpoint inhibitors and adjust their dosage. Indeed, the integration of the data obtained from the single-cell sequencing of immune cells with immune checkpoint inhibitors can increase the response rate of immune checkpoint inhibitors, decrease the immune-related adverse events, and facilitate tumoral cell elimination. This study aims to review key pathways involved in tumor development and shed light on single-cell sequencing. It also intends to address the shortcomings of immune checkpoint inhibitors, i.e., their varied response rates among cancer patients and increased risk of autoimmunity development, via applying the data from the single-cell sequencing of immune cells.     

Synthesis,crystallographic and spectroscopic studies,evaluation as antimicrobial and cytotoxic agents of a novel mixed-ligand nickel(II) complex

A new mononuclear mixed-ligand complex of Ni(II) has been synthesized and structurally characterized by single-crystal X-ray diffraction as [Ni(4-Cl-pydc)(apym)(H₂O)₂], where 4-Cl-pydc and apym are 4-chloropyridine-26-dicarboxylate and 2-aminopyrimidine, respectively. Spectroscopic studies such as FT-IR, UV-vis, ¹H-NMR, and thermal analysis (TGA/DTA) were carried out. The fluorescence properties were studied in solvents with different dipole moments. Antimicrobial activities of 4-chloropyridine-26-dicarboxylic acid (1), 2-aminopyrimidine (2), complex (3), and nickel(II) nitrate hexahydrate (4) were investigated by disk diffusion and broth microdilution methods against three Gram-positive bacteria, Staphylococcus aureus, Bacillus subtilis, Staphylococcus epidermidis and three Gram-negative bacteria, Escherichia coli, Pseudomonas aeruginosa, S. marcescens; also antifungal effect was evaluated on Aspergillus niger and Saccharomyces cerevisiae in vitro. The highest antibacterial activity of complex was observed nearly equal to gentamicin as a standard drug toward S. epidermids with IZD of 18 mm. The in vitro antiproliferative activity of 1–4 on H1299 (a human non-small cell lung carcinoma), HepG2 (a human liver hepatocellular carcinoma), and β-TC3 (a mouse beta pancreatic) cell lines was evaluated by MTT (3-(45-dimethylthiazol-2-yl)-25-diphenyl-2H-tetrazolium bromide) assay and, effect of complex on depolarization of mitochondrial membrane (MMP) of all three cell lines was measured by rhodamine 123. The highest cytotoxic effect of complex was exhibited toward H1299 cell line with IC₅₀ value equal to 10 μM.     

Investigation of cross-linked PVA/starch biocomposites reinforced by cellulose nanofibrils isolated from aspen wood sawdust

In this study, a bio-based composite prepared from cross-linked polyvinyl alcohol/starch/cellulose nanofibril (CNF) was developed for film packaging applications. For this purpose, CNF, as reinforcing phase, was initially isolated from aspen wood sawdust (AWS) using chemo-mechanical treatments, and during these treatments, hydrolysis conditions were optimized by experimental design. Morphological and chemical characterizations of AWS fibers were studied by transmission electron microscopy, scanning electron microscopy, Kappa number, and attenuated total reflectance-Fourier transform infrared spectroscopy, as well as National Renewable Energy Laboratory and ASTM procedures. Morphological images showed that the diameter of the AWS fibers was dramatically decreased during the chemo-mechanical treatments, proving the successful isolation of CNF. Moreover, chemical composition results indicated the successful isolation of cellulose, and Kappa number analysis demonstrated a dramatic reduction in lignin content. Mechanical, morphological, biodegradability, and barrier properties of biocomposites were also investigated to find out the influence of CNF on the prepared biocomposite properties. The mechanical results obtained from tensile analysis revealed that Young’s modulus and ultimate tensile strength of biocomposite films were enhanced with increasing CNF concentration, while a significant decrease was observed in elongation at break at the same concentration of CNF. Furthermore, with adding CNF, barrier properties and resistance to biodegradability were increased in films, whereas film transparency gradually declined.     

High-Efficiency Perovskite Solar Cells Enabled by Anatase TiO2 Nanopyramid Arrays with an Oriented Electric Field

One-dimensional (1D) nanostructured oxides are proposed as excellent electron transport materials (ETMs) for perovskite solar cells (PSCs); however, experimental evidence is lacking. A facile hydrothermal approach was employed to grow highly oriented anatase TiO₂ nanopyramid arrays and demonstrate their application in PSCs. The oriented TiO₂ nanopyramid arrays afford sufficient contact area for electron extraction and increase light transmission. Moreover, the nanopyramid array/perovskite system exhibits an oriented electric field that can increase charge separation and accelerate charge transport, thereby suppressing charge recombination. The anatase TiO₂ nanopyramid array-based PSCs deliver a champion power conversion efficiency of approximately 22.5 %, which is the highest power conversion efficiency reported to date for PSCs consisting of 1D ETMs. This work demonstrates that the rational design of 1D ETMs can achieve PSCs that perform as well as typical mesoscopic and planar PSCs.     

Numerical solution of functional integral equations by the variational iteration method

In the present article, we apply the variational iteration method to obtain the numerical solution of the functional integral equations. This method does not need to be dependent on linearization, weak nonlinearity assumptions or perturbation theory. Application of this method in finding the approximate solution of some examples confirms its validity. The results seem to show that the method is very effective and convenient for solving such equations.