Aqueous Content Research Articles

Role of CD 20+ T cells and related cytokines in mediating retinal microvascular changes and ocular complications in chronic-plaque type psoriasis

ObjectiveTo assess the role of CD3+ CD20+ CD4- CD8- double-negative (DN) or CD3+CD20+ CD4/CD8+ T cells and the related pro-inflammatory cytokines in the humor aqueous, in mediating retinal microvascular changes in patients with chronic plaque-type moderate to severe psoriasis.Design.A total of 76 patients (57.6 ± 11.7 years) with chronic plaque-type psoriasis were initially evaluated. Nineteen patients (19 eyes) and 19 healthy volunteers (19 eyes) were subjected to dermatological evaluation with Psoriasis Area Severity Index (PASI) and the Dermatology life quality index (DLQI). Retinal images were processed using an automatized software. On the same day, a venous sample was collected and analyzed using multiparametric flow cytometry. Three out of 6 patients who presented cataract, consented to perform surgery with humor aqueous collection. The samples were analyzed using a Multi-Analyte ELISA kit for the simultaneous quantification of IL1α, IL1β, IL2, IL4, IL6, IL8, IL10, IL12, IL17A, IFNγ, TNF-α, GMCSF. ResultsThe CD3+CD4+/CD8+CD20+CD56- T cells expression was greater in the psoriatic patients (+73.9%, P < 0.001) compared to controls, but not the DN T cells (-8.2%, P = 0.30). Ocular complications were diagnosed in 61.1% of patients, microvascular parameters including artero-venous ratio (P = 0.04), subfoveal choriocapillaris/Sattler’s layer, and choroidal thickness (CT, both P < 0.001) were significantly altered in psoriasis subgroup. The increased circulating levels of the CD3+CD4+/CD8+CD20+CD56- T cells were associated with thinning of subfoveal CT (P = 0.03) and Haller’s layer (P = 0.01). Instead, the DN T cells presented an inverse relationship with disease duration (P = 0.02), DLQI score (P = 0.02), and the use of biological therapy (P = 0.05). The related cytokine patterns possibly modified in this cellular context have been investigated. No significant differences were observed in cytokines levels between psoriasis and controls, the most significant difference was detected on IL-6, without reaching statistical significance (fold change of 1.4, P = 0.13). ConclusionOur findings demonstrated that CD20+ T cell subpopulation is highly represented in psoriasis regardless of the use of immunomodulatory therapies, and the diffuse microvascular alterations suggested possible endothelial damage as mainstream for the genesis of psoriatic-mediated complications as further supported by the comparable concentrations of cytokines, at least as humor aqueous content, with respect to healthy eyes.

Performance comparison of nonlinear and linear regression algorithms coupled with different attribute selection methods for quantitative structure - retention relationships modelling in micellar liquid chromatography

In micellar liquid chromatography (MLC), the addition of a surfactant to the mobile phase in excess is accompanied by an alteration of its solubilising capacity and a change in the stationary phase's properties. As an implication, the prediction of the analytes’ retention in MLC mode becomes a challenging task. Mixed Quantitative Structure – Retention Relationships (QSRR) modelling represents a powerful tool for estimating the analytes’ retention.This study compares 48 successfully developed mixed QSRR models with respect to their ability to predict retention of aripiprazole and its five impurities from molecular structures and factors that describe the Brij - acetonitrile system. The development of the models was based on an automatic combining of six attribute (feature) selection methods with eight predictive algorithms and the optimization of hyper-parameters. The feature selection methods included Principal Component Analysis (PCA), Non-negative Matrix Factorization (NMF), ReliefF, Multiple Linear Regression (MLR), Mutual Info and F-Regression. The series of investigated predictive algorithms comprised Linear Regressions (LR), Ridge Regression, Lasso Regression, Artificial Neural Networks (ANN), Support Vector Regression (SVR), Random Forest (RF), Gradient Boosted Trees (GBT) and K-Nearest neighbourhood (k-NN).A sufficient amount of data for building the model (78 cases in total) was provided by conducting 13 experiments for each of the 6 analytes and collecting the target responses afterwards. Different experimental settings were established by varying the values of the concentration of Brij L23, pH of the aqueous phase and acetonitrile content in the mobile phase according to the Box-Behnken design. In addition to the chromatographic parameters, the pool of independent variables was expanded by 27 molecular descriptors from all major groups (physicochemical, quantum chemical, topological and spatial structural descriptors). The best model was chosen by taking into consideration the Root Mean Square Error (RMSE) and cross-validation (CV) correlation coefficient (Q2) values.Interestingly, the comparative analysis indicated that a change in the set of input variables had a minor impact on the performance of the final models. On the other hand, different regression algorithms showed great diversity in the ability to learn patterns conserved in the data. In this regard, testing many regression algorithms is necessary in order to find the most suitable technique for model building. In the specific case, GBT-based models have demonstrated the best ability to predict the retention factor in the MLC mode. Steric factors and dipole-dipole interactions have proven to be relevant to the observed retention behaviour. This study, although being of a smaller scale, is a most promising starting point for comprehensive MLC retention prediction.

Evaluation of different approaches used to study membrane permeabilization by actinoporins on model lipid vesicles

Release of aqueous contents from model lipid vesicles has been a standard procedure to evaluate pore formation efficiency by actinoporins, such as sticholysin II (StnII), for the last few decades. However, regardless of the probe of choice, the results reported that StnII action was never able to empty the vesicles completely. This was hard to explain if StnII pores were to be stable and always leaky for the probes used. To address this question, we have used a variety of probes, including rhodamine 6G or Tb3+, to test the permeability of StnII's pores. Our results indicate that calcein was in fact too large to fit through StnII's pores, and that the standard method in the field is actually reporting StnII-induced transient permeation of the membrane rather than the passage of solutes through the stable assembled pores. In order to evaluate the permeability of these structures, we used a dithionite-based assay, which showed that the final pores were in fact open. Thus, our results indicate that the stable actinoporins' pores are open in spite of plateaued classic release curves. Besides the proper pore, the first stages of pore formation would inflict serious damage to living cells as well.

Disposition of two highly permeable drugs in the upper gastrointestinal lumen of healthy adults after a standard high-calorie, high-fat meal

ObjectivesTo quantify the presence of two model highly permeable drugs, paracetamol and danazol, in the upper gastrointestinal lumen under conditions simulating the situation after disintegration of immediate release dosage forms administered in bioavailability/bioequivalence studies in the fed state. To understand the drug transfer process from the antral contents through the upper small intestine based on luminal drug data. Methods8 healthy male adult volunteers participated in a randomized, single dose, two-phase, crossover study. After evaluating the impact of homogenization on meal's viscosity and particle size, the meal, containing phenol red as non-absorbable marker, was administered to the antrum via the gastric lumen of a naso-gastro-intestinal tube. The drugs were administered in solution form (Phase I) and in suspension form (Phase II) with a glass of tap water to the antrum of the stomach, 30 min after the initiation of meal administration. Samples were aspirated from the antrum and the upper small intestine up to 4 hours post drug administration. ResultsApparent concentrations in the aqueous contents of the antrum were higher than apparent concentrations in the micellar contents of the upper small intestine for paracetamol; the opposite was observed for danazol. Based on total drug amount per volume data in contents of the upper gastrointestinal lumen, the transfer of paracetamol (aqueous solution or suspension) and danazol (aqueous suspension) through the upper small intestine could be described as an apparent first-order process. Transfer of a long-chain triglyceride solution of danazol was highly variable. ConclusionsConcentrations in the aqueous/micellar phase of luminal contents and values of parameters controlling the transfer from bulk gastric contents through the upper small intestine after a high-calorie, high-fat meal, were reported for the first time for highly permeable drugs. Data are expected to enhance the development of biorelevant in vitro and physiologically based biopharmaceutics modelling methodologies.

Rheology of magnetic colloids containing clusters of particle platelets and polymer nanofibres.

Magnetic hydrogels (ferrogels) are soft materials with a wide range of applications, especially in biomedicine because (i) they can be provided with the required biocompatibility; (ii) their heterogeneous structure allows their use as scaffolds for tissue engineering; (iii) their mechanical properties can be modified by changing different design parameters or by the action of magnetic fields. These characteristics confer them unique properties for acting as patterns that mimic the architecture of biological systems. In addition, and (iv) given their high porosity and aqueous content, ferrogels can be loaded with drugs and guided towards specific targets for local (non-systemic) pharmaceutical treatments. The ferrogels prepared in this work contain magnetic particles obtained by precipitation of magnetite nanoparticles onto the porous surface of bentonite platelets. Then, the particles were functionalized by adsorption of alginate molecules and dispersed in an aqueous solution of sodium alginate. Finally, the gelation was promoted by cross-linking the alginate molecules with Ca2+ ions. The viscoelastic properties of the ferrogels were measured in the absence/presence of external magnetic fields, showing that these ferrogels exhibited a strong enough magnetorheological effect. This behaviour is explained considering the field-induced strengthening of the heterogeneous (particle-polymer) network generated inside the ferrogel. This article is part of the theme issue 'Patterns in soft and biological matters'.

Polyphenols/Flavonoids Analysis and Antimicrobial Activity in Pomegranate Peel Extracts

The use of plants still plays a vital role to establish the basic health requirements in developing countries. The extracts of P. granatum and its compounds have shown antimicrobial activity. This study showed that the acetone (125.36±0.01 and 70.5±0.01) extract contained the highest amount of total polyphenols (TPPC) and total flavonoids content (TFC) respectively compared to methanol (105.6±0.005 and 20.99±0.004) extract while methanol extract content was higher than ethanol (94.14±0.02 and14.48 ±0.005). The aqueous extracts content was the less one (83.17 ± 0.003 and 10.65±0.003). When study the antimicrobial activity of four different prepared concentrations of four pomegranate peel extracts against microorganisms including two Gram-positive bacteria [P. aeruginosa and S. aureus], one Gram-negative bacteria [A. baumannii] and Candida parapsilosis. The result shown the antimicrobial activity of acetone extract on all microorganisms the highest value followed by methanol, ethanol, and aqueous extract activity. Besides, the activity of all extracts was good excepted aqueous extract has low antimicrobial activity against S. aureus.

APPLICATION OF BIO-WASTE MATERIALS IN THE GREEN SYNTHESIS OF COMPOSITES FOR WATER PURIFICATION

Treatment of the polluted water has become an issue of cardinal importance in the framing of the most recent strategies that define the way the environmental engineering and conservation are being looked upon. Adsorption techniques that involve solid adsorbents have been widely practiced to filter out the contaminants from the aqueous contents, and composites of biopolymer have attracted greater attention because they are inherently innocuous to the environment and can be classified as bio-degradable. Biopolymer-based nano-composites in particular have often been proved to be possessing better physical, chemical, and mechanical properties than those of the corresponding biopolymers as such, and also provide the advantages of both counterparts in the composites. This paper details versatile biopolymer-based composites of cellulose extracted from banana peel impregnated with zero-valent iron nanoparticles aimed at the discharge of an organ othiophosphate pesticide from aqueous contents. The prepared composites were characterised by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, and Brunauer–Emmett–Teller analysis. The synthesis of the adsorbents, their intrinsic adsorption characteristics, and effective applications are the focal point of this paper and are subjected to detailed analysis.

Understanding the boundaries of life

Astrobiology Life on Earth has several universal chemical characteristics, including the presence of a lipid bilayer cell membrane that separates the aqueous cell contents from the environment. If life has evolved on other planets, it may use entirely different chemical components and principles. Polarity-inverted membrane structures composed of acrylonitrile, termed azotosomes, have previously been proposed as possible membrane alternatives under conditions that resemble those found on Saturn's moon Titan. Sandstrom and Rahm now argue, on the basis of molecular dynamics simulations, that azotosomes made of acrylonitrile in methane would be thermodynamically unstable and therefore unable to self-assemble in a manner similar to lipid bilayers. Such modeling efforts may be useful for constraining future speculation about what chemical assemblies are possible in unfamiliar environments. Sci. Adv. 10.1126/sciadv.aax0272 (2020).

Screening and Partial Characterization of Natural Antioxidants from Seaweeds Collected From, Rameshwaram Southeast Coast of India

The aim of this work is to estimate in-vitro antioxidant activities such as total antioxidant capacity, free radicals (DPPH) scavenging activity, hydrogen peroxides (H2 O2 ) scavenging activity, total reducing power scavenging activity and total phenols, of various extracts of seaweeds such as aqueous, acetone, ethanol, methanol, and pigments content by spectrophotometric method, of 33 seaweeds species among which 11 Chlorophyta, 11 Phaeophyceae and 11 Rhodophyta, collected during 2016 from two stations viz. Olaikuda and Vadakkadu, at Rameshwaram, southeast coast of India. Among four different extracts aqueous extracts from all seaweeds had minimum activity than acetone, methanol and ethanol. The Rhodophyta and Phaeophyceae had high antioxidant activity in comparing to Chlorophyta. The highest total antioxidant activity was found in acetone extract from Turbinaria decurrens (98.97±0.00%), followed by its methanol extract (98.81±0.60%) and ethanol extract (98.58±0.53%). The highest reducing power and H2 O2 scavenging activity were found in acetone extract of Caulerpa racemosa (383.25±1.04%), and methanol extract from Caulerpa racemosa var. macrophysa (24.91±0.49%). The methanol extract from Caulerpa scalpelliformis contained the highest total phenol (85.23±0.12%). The Chloro-a and Chloro-b contents were the highest in Gracilaria foliifera (13.69±0.38% mg/gm dry wt.) and Caulerpa racemosa var. macrophysa (9.12 ±0.12% mg/gm dry wt.) likewise carotenoid was also the highest in Gracilaria foliifera (0.054±0.0003% mg/gm dry wt.) and Caulerpa racemosa var. macrophysa (0.04 ±0.002% mg/gm dry wt.). The partial characterization of the extract which contents the highest activity was done by UV-Visible Spectrophotometer, FTIR, and NMR. The functional groups and all the possible compounds present in the extract were partially characterized. It can be concluded from this study, that some seaweed extract can be used for natural antioxidant production, after further characterization to negotiate the side effect of synthetic, market available antioxidants.

Reply.

Arshinoff and Modabber5 call into question two assumptions of our mathematical model describing the residence times of moxifloxacin in the anterior segment with two different intracameral injection strategies.1 The authors of the letter agree with us on the underlying principle of our publication but disagree on the volume of the anterior chamber (AC) and the half-life of antibiotics. We selected two representative mean pseudophakic AC volumes (0.19 mL and 0.33 mL), substantiated by the literature,2,3 to demonstrate the principle that injecting the same dose of antibiotics (eg, 500 μg) into ACs with varying volumes produces varying concentrations of antibiotics within the total aqueous humor volume. The larger volume of 0.33 mL of Matsuura was derived from aqueous humor sampling immediately after intracameral injection in humans, before any possible fibrosis of the capsule. Libre and Mathews4 also agree with this volume. Arshinoff and Modabber's5 estimation of 0.5 mL is based on a mean phakic AC volume in the human eye of 0.25 mL; however, measurements of the AC volume in the elderly phakic eye average only 0.15 mL.6,7 With this experimentally derived volume, Arshinoff's estimation of the mean pseudophakic aqueous volume would be 0.4 mL, close to Matsuura and Libre's reported value of 0.33 mL. The AC size is known to vary from patient to patient, which cataract surgeons recognize when operating on smaller eyes and myopic eyes with longer axial lengths and larger chambers. Therefore, attempting to replace the aqueous contents with an antibiotic solution of known concentration will achieve the more consistent final concentration of drug, irrespective of the patient's pseudophakic AC volume. This same principle would have been demonstrated had we chosen two different AC volumes. There is a wide variation in the reported half-life elimination of antibiotics in the AC. Generally speaking, interdrug variation in elimination times, especially in the eye, may be due to factors such as differences in the drug molecular size, tissue binding, active pump mechanisms, and obstructions or reductions to outflow and drug elimination. Asena obtained antibiotic half-lives between 1.2 hours and 13 hours in rabbits, depending on which time points were used8; Lipnitzki et al.9 found between 0.64 hours and 1.8 hours in rabbits. Matsuura et al.3,10 demonstrated a half-life in rabbits and humans that averaged 1.2 hours over most time points. We chose 1.2 hours as it agrees with the 1% per minute aqueous turnover rate noted by Goel et al.11 The varied measures of the intradrug half-life elimination time of moxifloxacin and other antibiotics in the AC may be due to imprecision in injection and sampling techniques, pharmacokinetics that are not single compartment, and variations in individual subject anatomy and physiology. We would caution against the speculation of postantibiotic effects in regard to half-life because efficacy should be related to the target microorganism.12 Furthermore, principles that apply to the multidose administration of antibiotics in the treatment of systemic infections should not be presumptively applied to the scenario of single-dose intraocular injection without empirical evidence. Our study used two different and substantiated aqueous volumes and demonstrated that injecting small volumes of an agent can result in unequal final drug concentrations in the AC. Given the patient-to-patient variations, the “flushing” or large-volume injection technique should offer some degree of standardization and assurance of a more uniform final drug concentration in the pseudophakic AC as compared with smaller-volume–injected aliquots, thereby minimizing the interpatient variable of AC volume differences during cataract surgery.

Salt-driven assembly of magnetic silica microbeads with tunable porosity

HypothesisPorous magnetic silica beads are promising materials for biological and environmental applications due to their enhanced adsorption and ease of recovery. This work aims to develop a new, inexpensive and environmentally friendly approach based on agglomeration of nanoparticles in aqueous droplets. The use of an emulsion as a geometrical constraint is expected to result in the formation of spherical beads with tunable composition depending on the aqueous phase content. ExperimentsMagnetic silica beads are produced at room temperature by colloidal destabilization induced by addition of CaCl2 to a water-in-oil emulsion containing SiO2 and Fe3O4 nanoparticles. The impact of the salt concentration, emulsification method, concentration of hydrophobic surfactant as well as silica content is presented in this paper. FindingsThis method enables the production of spherical beads with diameters between 1 and 9 µm. The incorporation of magnetic nanoparticles inside the bead’s structure is confirmed using Energy Dispersive X-ray spectrometry (EDX) and Scanning Transmission Electron Microscopy (STEM) and results in the production of magnetic responsive beads with a preparation yield up to 84%. By incorporating the surfactant Span 80 in the oil phase it is possible to tune the roughness and porosity of the beads.

Research of oil-based drilling fluids to improve the quality of wells completion

The aim of the work is to increase the well completion efficiency when using oil-based drilling fluids. In this study, the effect of the aqueous phase content on the change in the rheological parameters of the solutions and the effect of the type of asphalt on the structural-rheological and filtration parameters of the oil-based solution was conducted. Studies have shown the effectiveness of various types of asphalt in OBM systems, the obtained dependencies on the effect of the Oil-water ratio can be used in production to select the optimal ratio for the selection of specific properties of solutions.

Isopropanol, n‐butanol and ethanol recovery from IBE model solutions by salting‐out using potassium pyrophosphate

AbstractBACKGROUNDIsopropanol, n‐butanol and ethanol (IBE) could be used as a clean and renewable biofuel. However, the separation and purification of IBE requires more energy due to the low concentration of IBE in fermentation broth and the existence of azeotropes. Here, we investigate in detail the separation ability of IBE from two typical model solutions by salting‐out with potassium pyrophosphate (K4P2O7) as the salting‐out agent.RESULTSIncreasing the salt content could effectively increase the distribution coefficient and selectivity coefficient of IBE. The recovery of IBE was over 95 wt%, and the dehydration ratio could reach above 99.8 wt%. A higher total organic compound content could increase the recovery of IBE but could decrease the dehydration ratio. The logarithm of solubility of IBE in the aqueous phase or water content in the organic phase has a good linear relationship with the molality of K4P2O7.CONCLUSIONThis study demonstrated the ability of K4P2O7 to recover IBE from IBE model solutions during the separation process. The results showed that the salting‐out method has the potential to save energy in recovering IBE from a real fermentation broth. © 2019 Society of Chemical Industry

Bacterial dynamin-like protein DynA mediates lipid and content mixing.

Many bacterial species contain dynamin-like proteins (DLPs). However, so far the functional mechanisms of bacterial DLPs are poorly understood. DynA in Bacillus subtilis is a 2-headed DLP, mediating nucleotide-independent membrane tethering in vitro and contributing to the innate immunity of bacteria against membrane stress and phage infection. Here, we employed content mixing and lipid mixing assays in reconstituted systems to study if DynA induces membrane full fusion, characterize its subunits in membrane fusion, and further test the possibility that GTP hydrolysis of DynA may act on the fusion-through-hemifusion pathway. Our results based on fluorescence resonance energy transfer indicated that DynA could induce aqueous content mixing even in the absence of GTP. Moreover, DynA-induced membrane fusion in vitro is a thermo-promoted slow process, and it has phospholipid and membrane curvature preferences. The D1 part of DynA is crucial for membrane binding and fusion, whereas D2 subunit plays a role in facilitating membrane fusion. Surprisingly, digestion of DynA mediated an instant rise of content exchange, supporting the assumption that disassembly of DynA is a driving force for fusion-through-hemifusion. DynA is a rare example of a membrane fusion catalyst that lacks a transmembrane domain and hence sets this system apart from well-characterized fusion systems such as the soluble N-ethyl maleimide sensitive factor attachment protein receptor complexes.-Guo, L., Bramkamp, M. Bacterial dynamin-like protein DynA mediates lipid and content mixing.

IN VITRO DEGRADATION OF POLYDIOXANONE (PDO) LIFTING THREADS IN HYALURONIC ACID (HA).

Background: Recently, some clinicians have proposed implanting PDO threads imbibed in hyaluronic acid (HA). However, this is controversial since PDO sutures are hydrophilic and the presence of HA could increase the rate of hydrolysis. Aim: To demonstrate the degradation of PDO lifting threads in HA through ultramicroscopy. Materials and methods: Three, one cm long, segments of 23G PDO threads, where immersed in 1.5 ml non-crosslinked hyaluronic acid in previously labeled, sterile microcentrifuge tubes. These were observed by ultramicroscopy at 4x and 10x after 24, 48 and 72 hours. Results: Microphotographs taken after 24 hours already show structural changes in the fibers, presenting an increase in interlaminar spaces and dilution of violet pigmentation. At 48 hours, degradation continues. PDO hygroscopy is observed as aqueous content between the peripheral layers and the central core of the thread. Some fibers show breakage, and there is an increase in interlaminar and interfibrillar spaces. At 72 hours, as the pigment is released, larger empty spaces are observed in the central column of the thread, and there is disorganization of the peripheral fibrils with fraying all along the fiber. Conclusions: Hyaluronic acid induces rapid biodegradation of the PDO thread by hydrolysis beginning 24 hours after contact of the thread with the biomaterial. We hypothesize that non-crosslinked hyaluronic acid is a powerful catalyzing agent for hydrolytic degradation of the PDO thread, since this thread is highly hydrophilic. Thus, we suggest that clinically embedding PDO threads with HA will only accelerate biodegradation of the suture.&#x0D; Key words: Lifting threads, polydioxanone, hyaluronic acid, biodegradation, PDO hydrolysis

Evaluation of laminar flow of surfactant-stabilized bitumen-in-water emulsion in pipe using computational fluid dynamics: Effects of water content and salinity

Laminar flow of oil-in-water (O/W) emulsion in a horizontal pipe has been simulated to quantify the effect of salinity of aqueous phase and water content on flow characteristics using computational fluid dynamics (CFD). Bitumen was dispersed in aqueous solution containing surfactant at different NaCl concentrations and water contents. Rheological parameter was obtained from the viscosity-shear rate profiles of the fluid. Numerical modeling and simulation was performed using a finite element simulation software. The case was simplified by considering the O/W emulsion as a stable, pseudo-homogeneous (single-phase) fluid within the conditions investigated. At flow reference temperature, Tref = 30 °C, the pressure drop obtained from emulsion with 30% water content was 931 Pa, compared to 84.6 Pa which was obtained from 50% water content (i.e. reference fluid without NaCl). In addition, the pressure drop of 239 Pa, 142 Pa, 124 Pa, and 82.9 Pa was obtained from O/W emulsion samples containing 70000 ppm, 40000 ppm, 20000 ppm, and 10000 ppm salinity in the aqueous phase, respectively. Furthermore, the maximum dynamic viscosity imposed by the fluid, was calculated as ≈81000 cP for the sample containing 30% water content compared to ≈14000 cP from the reference fluid. The dynamic viscosity obtained from 70000 ppm salinity content was ≈34000 cP compared to ≈20000 cP, ≈16000 cP, and ≈13000 cP calculated for 40000 ppm, 20000 ppm, and 10000 ppm salinity, respectively. Moreover, large reduction in pressure drop (99%) and dynamic viscosity (60–90%), regardless of the water content and salinity were obtained from the simulation.

A ratiometric 4-amido-1,8-naphthalimide fluorescent probe based on excimer-monomer emission for determination of pH and water content in organic solvents

The pH and water content in organic solvents are some of the most important parameters that play a key role in chemical laboratories, clinical analysis, food processing, biomedical and environmental monitoring, and life sciences. Herein we are reporting on the design, synthesis and sensor activity of a novel 4-amido-1,8-naphthalimide ratiometric fluorescent pH probe based on excimer-monomer switching mechanism. The fluorescence chemosensing behavior of the synthesized compound was studied in solvents of different polarity and the results obtained clearly demonstrates the great opportunity of the novel probe selectively to determine pH in aqueous solutions and water content in organic environment.

Hydrotrope-Driven Self-Assembly in CTAB/ n-Hexanol/Water/Heptane Reverse Micellar System.

Self-organization of nanoparticles into one-dimensional (1D) nanochains leads to new unpredicted physiochemical properties, which are further exploited to develop photonic or electronic devices. Thus, the controlled fabrication of 1D nanochains requires nanotemplate, which acts as building blocks for the self-assembly of nanoparticles. To address this issue, we designed a hydrotrope (sodium salicylate)-based CTAB/ n-hexanol/water/heptane reverse micellar system. Hydrotrope, herein, modulates electrostatic interactions between reverse micellar droplets and paves the way for the formation of self-assembled structures. Small-angle X-ray scattering studies were performed on the CTAB/heptane reverse micellar system by varying hydrotrope concentrations and water-to-surfactant ratios (W x). The aqueous content of the reverse micellar pool is determined from the W x value, where W x = [H2O]/[CTAB] and [CTAB] = 0.05 M. SAXS studies were performed for CTAB/heptane reverse micellar systems at three different W x values, that is, 6, 12, and 16 and represented by W6, W12, and W16, respectively. All SAXS profiles were modeled with a spherical form factor and a Baxter sticky hard sphere structure factor. The interaction between droplets was predicted in terms of stickiness parameter. The effect of W x on the formation of self-assembled structures and forces governing the assembly has been discussed in detail. For the W6 system, the electrostatic repulsion between reverse micellar droplets decreases, resulting in the formation of the 1D chain-like assembly of nanodroplets. In the case of the W12 system, the dual feature of the hydrotrope has been observed, it increases the size of the reverse micellar system and reduces electrostatic repulsion between droplets because of which the formation of chain-like assemblies cannot be determined with accuracy. For the W16 system, the decrease in micellar size with the increase in the hydrotrope concentration has been observed. Thus, our reverse micellar templates may provide a comprehensive method for the fabrication of high aspect ratio 1D nanochains of a variety of materials and harnessing their collective properties for magnetic, catalytic, and opto-electronic applications.

Rheology and structure of oleogelled water-in-oil emulsions containing dispersed aqueous droplets as inactive fillers

The effect of dispersed aqueous droplets on the structure and rheology of rice bran wax (RBX) oleogels was investigated. Water-in-oil (W/O) emulsions containing up to 50 wt% water dispersed in canola oil were generated with polyglycerol polyricinoleate (PGPR) as the oil-soluble surfactant. The presence of both the RBX and PGPR resulted in oleogelled W/O emulsions stable against coalescence and phase separation for at least 28 days. The key contributor to emulsion structure and stability was the wax crystal network itself as the droplets behaved as an inactive filler. The oleogelled emulsions demonstrated structural weakening with increasing water content in terms of rigidity and thixotropic behaviour, both of which were attributed to the decrease in RBX content. Importantly, emulsion elastic modulus was near identical to its corresponding control where the dispersed phase was replaced by an equivalent wt% of continuous phase oil instead. Overall, this study demonstrated that even with dispersed droplets behaving as an inactive filler, it is possible to generate kinetically-stable oleogelled W/O emulsions with a high aqueous phase content.

Enantioseparation of tryptophan and its unnatural derivatives by nano-LC on CSP-teicoplanin silica based.

This work deals with the potentiality of nano liquid chromatography (Nano-LC) for the chiral separation of racemic mixture of tryptophan and some selected derivatives by using 100µm i.d. fused silica capillary packed with teicoplanin bonded to 5µm diol silica stationary phase. The experiments were carried out by using a cheap and laboratory-assembled nano-LC-UV system. Elution was done in an isocratic mode using a polar organic mobile phase. In order to find the optimum chiral separation of the studied enantiomers, some chromatographic experimental parameters were systematically studied and optimized. Among them, mobile phase composition, namely organic modifier type and concentration, buffer type and pHand aqueous content and sample solvent dilution on retention time, retention factor and enantioresolution factor were studied. Baseline enantioresolution and good peak shape was achieved utilizing the mobile phase containing 40mM ammonium formate at pHpH2.5 in ACN/water/acetone (60:30:10, v/v/v) at 520nL/min in less than 8min analysis time.