PA Concentration Research Articles

Enteroendocrine cell-derived peptide YY signalling is stimulated by pinolenic acid or Intralipid and involves coactivation of fatty acid receptors FFA1, FFA4 and GPR119

Long chain fatty acids are sensed by enteroendocrine L cells that express free-fatty acid receptors, including FFA1, FFA4 and the acylethanolamine receptor GPR119. Here we investigated the acute effects of single or multiple agonism at these G protein-coupled receptors in intestinal mucosae where L cell-derived peptide YY (PYY) is anti-secretory and acts via epithelial Y1 receptors. Mouse ileal or colonic mucosae were mounted in Ussing chambers, voltage-clamped and the resultant short-circuit current (Isc) recorded continuously. The agonists used were; FFA1, TAK-875 or AM-1638; for FFA4, Merck A; or for GPR119, AR231453, PSN632408 or AR440006. Their responses were compared with those of pinolenic acid (PA, a presumed dual FFA1/FFA4 agonist) and the lipid emulsion, Intralipid. The FFA1 agonist AM-1638 (EC50 = 38.2 nM) was more potent than TAK-875 (EC50 = 203.1 nM) but exhibited similar efficacy. GPR119 agonism (AR231453) pretreatment enhanced subsequent FFA1 (AM-1638 or TAK-875) and FFA4 (Merck A) signalling. PA (EC50 = 298.2 nM) co-activated epithelial FFA1 and FFA4 and involved endogenous PYY Y1/Y2-receptor mechanisms but desensitisation was observed between PA and high GPR119 agonist concentrations. Apical Intralipid co-activated FFA1, FFA4 and GPR119 with a residual component not being attributable to PYY, or this trio of fatty acid receptors.

Polyamide microplastics can mitigate the effects of pathogenic bacterium on the health of marine mussels

Vibrio parahaemolyticus and microplastics are prevalent in the ocean. Bacteria attach onto plastic particles, forming harmful biofilms that collectively threaten bivalve health. This study investigates the interaction between polyamide microplastics (PA: particle size 38 ± 12 µm) and V. parahaemolyticus, as well as their combined impact on thick-shelled mussels (Mytilus coruscus). We introduced 1011 CFU/L of V. parahaemolyticus into varying PA concentrations (0, 5, 50, and 500 particles/L) to observe growth over 14 h and biofilm formation after 48 h. Our findings indicate that microplastics suppress biofilm formation and virulence gene expression. Four treatments were established to monitor mussel responses: a control group without PA or V. parahaemolyticus; a group with 50 particles/L PA; a group with 1011 CFU/L V. parahaemolyticus; and a co-exposure group with both 50 particles/L PA and 1011 CFU/L V. parahaemolyticus, over a 14-day experiment. However, combined stress from microplastics and Vibrio led to immune dysregulation in mussels, resulting in intestinal damage and microbiome disruption. Notably, V. parahaemolyticus had a more severe impact on mussels than microplastics alone, yet their coexistence reduced some harmful effects. This study is the first to explore the interaction between microplastics and V. parahaemolyticus, providing important insights for ecological risk assessments.

Exploring the twin potential of nanostructured TiO2:SeO2 as a promising visible light photocatalyst and selective fluorosensing platform

The present work describes the development of TiO2/SeO2 nanostructure as a potential candidate for visible light photocatalysis as well as selective fluorophore for the sensing of picric acid. The obtained nanostructure consists of uniform globular nanoparticles having approximate size of 170 nm and possess an optical band gap of 2.33 eV with absorption maxima at 473 nm. The photocatalyst was able to achieve 90.34% degradation efficiency for 2, 4-dichlorophenol (2,4-DCP) with rate constant of 0.0046 min−1 in the visible region. Further the nanostructure was able to serve as a selective fluorophore for sensing of Picric acid portraying more than 95% of fluorescence quenching when the concentration of PA is 10–4 M. Theoretical calculations indicate the interaction of organic pollutants with the nanostructure and reveal that both picric acid (− 66.21 kcal/mol) and 2,4-DCP (− 12.31 kcal/mol) possess more negative binding energy values demonstrating a strong interaction of both with the nanostructure, making it suitable for the degradation as well as sensing of organic pollutants. Thus this study explains the potential of prepared catalyst for waste water treatment.

Electron beam-assisted exfoliation of boron nitride and covalent functionalization

A facile, scalable exfoliation technique is still required for further modification to cater to any potential application for two-dimensional boron nitride. This paper discusses the radiation-assisted exfoliation of hexagonal boron nitride (h-BN) using electron beam irradiation and followed by functionalization with phosphoric acid 2-hydroxyethyl methacrylate ester (PA) to facilitate targeted applications. h-BN is dispersed in NaOH solution and subjected to mild sonication to facilitate ion intercalation between the layers. The sonicated h-BN solution was exposed to electron beam irradiation for BNNS exfoliation. The degree of exfoliation was measured in terms of d-spacing derived from XRD using Bragg's law. The effect of irradiation dose, energy, NaOH concentration, and mass of h-BN, on exfoliation degree was investigated. XRD analysis was used to compute the d-spacing, crystallinity, and crystal size of h-BN after irradiation. The d-spacing attained for pristine h- BN was 0.334 nm, however it increases to 0.337 nm upon irradiation at 100 kGy doses, 3 MeV of energy, and 0.1 g of h-BN in 80 mL of 30 % NaOH solution. The occurrence of radiation-assisted exfoliation and its mechanism were supported by FTIR, TGA, Raman, FESEM, XPS, AFM, and TEM analyses. The exfoliated BN was functionalized with PA. The degree of functionalization was measured by phosphoric density (mmol/g) via the acid-base titration method. The effect of PA concentration, reaction temperature and mass on phosphoric density was also investigated. The highest phosphoric density attained was approximately 13.32 mmol/g at 10 % PA, 0.1 g of exfoliated BN, 80 °C, and 5 h. The incorporation of PA onto exfoliated BN was further confirmed by XRD, FTIR, TGA, Raman, FESEM-EDX, and XPS analyses. Conclusively, this study reveals a facile dual-step exfoliation and functionalization technique of h-BN nanosheet through radiation assisted exfoliation technique.

Preparation of n-doped carbon quantum dots for the detection of PA in real explosion dust samples

Nitrogen doping carbon quantum dots (N-CQDs) are synthesized using o-phenylenediamine as a carbon and nitrogen source via the water hydrothermal method. The size of the obtained N-CQDs is about 5.51 nm, and FTIR results show that their surface contains many –OH and –NH2 groups. N-CQDs can selectively recognize PA and its homologous (DNP and NP) in the presence of other analytes (including TNT, Tetryl, PETN, RDX, HMX, NC, NG, DNT, NT, NB, DNP, NP, BP, PC, AN, Ca2+, Cl-, Mg2+, Na+, H2O2). A linear correlation is also observed between PA concentration (0 ∼ 10.0 μmol/L) and N-CQDs fluorescence intensity (0.05 mg/mL) at 556 nm. The linear curve is y = -3.64 × 107x + 404.91, and the detection limit is ∼ 70 nmol/L. The Stern-Volmer graphs lack sufficient linearity, confirming the static quenching interaction between N-CQDs and PA. Finally, the N-CQDs are successfully applied to determine PA content in simulated and real samples quantitatively.

Pentadecanoic acid (C15:0, PA) induces mild maternal glucose intolerance and promotes the growth of the offspring partly through up-regulating liver PPARα and MAPK signaling pathways.

Gestational diabetes mellitus (GDM) is one of the most common metabolic disturbances during pregnancy, which poses a serious threat to both maternal and offspring health. Pentadecanoic acid (C15:0, PA) is one of the most common odd-chain saturated fatty acids (OCS-FAs). However, its safety and nutritional value are yet to be verified. Herein, we provide a systematic assessment of the effects of PA on maternal and progeny health and insulin sensitivity for the first time. Our results showed that consumption of 1% PA during pregnancy could increase the contents of PA and heptadecanoic acid (C17:0) in maternal plasma, fetal tissue and offspring plasma, but it had no effect on embryonic development. During pregnancy, PA treatment caused mild insulin resistance, while it had little effect on the maternal body composition. During lactation, PA treatment caused mild insulin resistance and oxidative stress. Maternal body fat deposition was also reduced, but the growth rate of the offspring was faster. It is worth noting that PA treatment decreased plasma and liver TG content and increased the antioxidant capacity of the offspring. The effect of PA on the transcription and expression genes in the liver of pregnant mice was investigated using RNA-seq. PPARα and MAPK signaling pathways, both closely related to lipolysis, inflammation, oxidative stress, and insulin resistance were significantly increased. The expression of c-JUN, ERK, JNK and P65 proteins was also significantly up-regulated. In conclusion, our results suggest that 1% PA can induce a mild decrease in the maternal glucose tolerance and lipolysis mainly by activated MAPK and PPARα signaling. Moreover, low concentrations of PA may be an effective nutrient to alleviate the oxidative stress and reduce blood lipid levels of offspring.

Growth/no-growth models of propionic and sorbic acid for bread and cake moulds

Propionic and sorbic acid are very effective weak-organic acid preservatives in bakery products. Their pH-dependent antifungal activity, the role of undissociated acid and the importance of the aqueous phase was studied. Besides looking for new natural preservation techniques the gain of further knowledge on their activity is still highly relevant to tackle the problem of food waste. In this study, the susceptibility of spoilage moulds for propionic (PA) and sorbic acid (SA) was tested in-vitro and in bread and cake. Aspergillus niger, Aspergillus montevidensis, Aspergillus ruber, Cladosporium ramotenellum, Penicillium brevicompactum and Penicillium roqueforti were subjected to PA and SA, both through macrodilution on malt extract agar (MEA) plates with adjusted aw (0.93, 0.95, 0.97), pH (5, 5.5, 6.0), acid (max. 2000 mg/L MEA), and through validation in wheat bread (max. 2901 mg PA/kg) and (lemon) cake (max. 1988 mg SA/kg). The undissociated acid concentrations (CHA) were estimated using either the Henderson-Hasselbalch (HH) equation or two modified HH equations. The influence of the food matrix (liquid oil, water, pH, aw), partitioning coefficient of the acids and spoilage fungi were evaluated and results were compared with in-vitro predictive models. In bread, the regular HH eq. proved to have good predictive power of CHA, whereas in cake a modified HH eq. (model 2) had better performance due to the inclusion of potential loss of CHA in the oil phase of complex food systems. The minimal inhibitory concentration (MIC) of PA in bread, after 30 days, was higher than 2901 mg/kg bread due to the strong resistance of P. brevicompactum, P. roqueforti and A. montevidensis. MIC of SA in lemon cake was 1429 mg SA/kg (pH 5.2), whereas in standard cake with pH 7.2, the max. level of 1988 mg SA/kg was insufficient for postponing mould growth to 30 days. The pH of cake had no influence on MIC of SA against A. niger and A. rubrum, whereas this effect was seen for C. ramotenellum, P. brevicompactum and P. roqueforti.

Polyalthic Acid from Copaifera lucens Demonstrates Anticariogenic and Antiparasitic Properties for Safe Use.

This study aimed at evaluating the potential of Copaifera lucens, specifically its oleoresin (CLO), extract (CECL), and the compound ent-polyalthic acid (PA), in combating caries and toxoplasmosis, while also assessing its toxicity. The study involved multiple assessments, including determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against cariogenic bacteria. CLO and PA exhibited MIC and MBC values ranging from 25 to 50 μg/mL, whereas CECL showed values equal to or exceeding 400 μg/mL. PA also displayed antibiofilm activity with minimum inhibitory concentration of biofilm (MICB50) values spanning from 62.5 to 1000 μg/mL. Moreover, PA effectively hindered the intracellular proliferation of Toxoplasma gondii at 64 μg/mL, even after 24 h without treatment. Toxicological evaluations included in vitro tests on V79 cells, where concentrations ranged from 78.1 to 1250 μg/mL of PA reduced colony formation. Additionally, using the Caenorhabditis elegans model, the lethal concentration (LC50) of PA was determined as 1000 μg/mL after 48 h of incubation. Notably, no significant differences in micronucleus induction and the NDI were observed in cultures treated with 10, 20, or 40 μg/mL of CLO. These findings underscore the safety profile of CLO and PA, highlighting their potential as alternative treatments for caries and toxoplasmosis.

Effects of 1,2,3-Propanetricarboxylic acid on the hydration and microstructure of fluorogypsum

Aiming at the issues of poor hydration activity, long setting time, and low early strength in industrial by-product fluorogypsum (FG), 1,2,3-propenyltricarboxylic acid (PA) was utilized to enhance its reactivity. The mechanism was investigated using modern analytical techniques such as XRD, 1H low-field NMR, and FTIR spectroscopy. The results indicate that the incorporation of PA can significantly augment the rate of FG hydration and enhance its hydration activity. The optimal concentration of PA was determined to be 0.008%. The FG paste exhibited a reduction in setting time by approximately 500 min compared to the control sample. Furthermore, the flexural and compressive strengths increased by 29.6% (reaching 3.5 MPa) and 40.2% (reaching 40.1 MPa), respectively, after a curing period of 28 d. Through the process of physical adsorption, PA facilitates the transformation from anhydrite (CaSO4-II) to dihydrate gypsum (CaSO4·2H2O). Subsequently, PA promotes the growth of dihydrate gypsum crystals along each crystal axis, resulting in the formation of regular hexagonal prisms. The prismatic crystals of dihydrate gypsum are arranged in a closely packed, layered structure that results in reduced pore and porosity content, and enhanced mechanical strength.

Effects of dietary standardized ileal digestible lysine to net energy ratio and wheat level on growth performance, meat quality, intestinal microbiota and body metabolism of finishing pigs

Lowing lysine (Lys): energy ratio based on corn-soybean diets could increase intramuscular fat (IMF) content, the effectiveness of it in enhancing IMF content when corn is partially substituted by wheat is unclear. This study aimed to determine the effects of dietary wheat levels and standardized ileal digestible (SID) Lys: net energy (NE) ratio on growth performance and meat quality, alteration in gut microbiota and body metabolism, as well as its correlation with meat quality are revealed via combined microbiome and metabolomic methods. A total of 72 pigs were randomly divided into four groups and fed with high SID Lys:NE ratio (HR) diets containing 25% wheat (W25HR), low SID Lys:NE ratio (LR) diets containing 25% wheat (W25LR), HR diets containing 55% wheat (W55HR) or LR diets containing 55% wheat (W55LR). Increasing dietary wheat level impaired feed utilization during 65–90 kg phase (P < 0.05) and enhanced meat color values (P < 0.05) of longissimus dorsi (LD) in finishing pigs. Enhancing dietary wheat level decreased relative abundance of Lactobacillus and Coprococcus (P < 0.05), and inhibited microbial carbohydrate metabolism capacity (P < 0.05) in colon of finishing pigs. Changes in microbial composition and carbohydrate metabolism capacity caused by wheat level led to alteration in meat color. LR diets improved feed utilization (P < 0.05), affected amino acid and lipid metabolism, and increased IMF content in LD (P < 0.05). Reducing SID Lys:NE ratio changed the concentrations of PA, delta-tocopherol, L-arginine, AzA, BA, and L-carnitine at the 25% wheat level and ARA, SDA, Glu, fructose-6-phosphate, and isorhamnetin at the 55% wheat level in the serum (P < 0.05, VIP > 1), which could serve as key biomarkers for predicting meat quality. LR diets upregulated mRNA expression levels of CCAAT/enhancer binding protein (C/EBP) α (P < 0.05), C/EBPβ (P < 0.01), sterol regulatory element-binding transcription factor 1c, fatty acid synthase (FAS) (P < 0.05), while downregulated mRNA abundance of adipose triglyceride lipase (ATGL) (P < 0.05) in liver at the 25% wheat level. The mRNA expression levels of C/EBPβ (P < 0.01), FAS, acetyl-coA carboxylase and fatty acid binding protein 1 (P < 0.05) were higher in the W55LR than W55HR groups, whereas mRNA abundance of ATGL was lower (P < 0.05). These results indicated that lowering SID Lys:NE ratio promoted lipogenesis, inhibited lipolysis and improved IMF deposition in LD via altering serum metabolism in different manner at two wheat level. LR diets containing 25% wheat was recommended to enhance the growth performance of finishing pigs, while concurrently achieving higher IMF content and improved meat color in the LD.

Heteroatom-Doped Carbon Quantum Dots and Polymer Composite as Dual-Mode Nanoprobe for Fluorometric and Colorimetric Determination of Picric Acid.

Oxygen- and nitrogen-heteroatom-doped, water-dispersible, and bright blue-fluorescent carbon dots (ON-CDs) were prepared for the selective and sensitive determination of 2,4,6-trinitrophenol (picric acid, PA). ON-CDs with 49.7% quantum yield were one-pot manufactured by the reflux method using citric acid, d-glucose, and ethylenediamine precursors. The surface morphology of ON-CDs was determined by scanning transmission electron microscopy, high-resolution transmission electron microscopy, dynamic light scattering, Raman, infrared, and X-ray photoelectron spectroscopy techniques, and their photophysical properties were estimated by fluorescence spectroscopy, UV-vis spectroscopy, fluorescence lifetime measurement, and 3D-fluorescence excitation-emission matrix analysis. ON-CDs at an average particle size of 3.0 nm had excitation/emission wavelengths of 355 and 455 nm, respectively. With the dominant inner-filter effect- and hydrogen-bonding interaction-based static fluorescence quenching phenomena supported by ground-state charge-transfer complexation (CTC), the fluorescence of ON-CDs was selectively quenched with PA in the presence of various types of explosives (i.e., 2,4,6-trinitrotoluene, tetryl, 1,3,5-trinitroperhydro-1,3,5-triazine, 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane, pentaerythritol tetranitrate, 3-nitro-1,2,4-triazole-5-one, and TATP-hydrolyzed H2O2). The analytical results showed that the emission intensity varied linearly with a correlation coefficient of 0.9987 over a PA concentration range from 1.0 × 10-9 to 11.0 × 10-9 M. As a result of ground-state interaction (H-bonding and CTC) of ON-CDs with PA, an orange-colored complex was formed different from the characteristic yellow color of PA in an aqueous medium, allowing naked-eye detection of PA. The detection limits for PA with ON-CDs were 12.5 × 10-12 M (12.5 pM) by emission measurement and 9.0 × 10-10 M (0.9 nM) by absorption measurement. In the presence of synthetic explosive mixtures, common soil cations/anions, and camouflage materials, PA was recovered in the range of 95.2 and 102.5%. The developed method was statistically validated against a reference liquid chromatography coupled to tandem mass spectrometry method applied to PA-contaminated soil. In addition, a poly(vinyl alcohol)-based polymer composite film {PF(ON-CDs)} was prepared by incorporating ON-CDs, enabling the smartphone-assisted fluorometric detection of PA.

Polygoni Multiflori Radix Praeparata and Acori Tatarinowii Rhizoma ameliorate scopolamine-induced cognitive impairment by regulating the cholinergic and synaptic associated proteins.

The combination of Polygoni Multiflori Radix Praeparata (PMRP) and Acori Tatarinowii Rhizoma (ATR) is often used in traditional Chinese medicine to prevent and treat Alzheimer's disease (AD). However, it is not clear whether the effects and mechanisms of the decoction prepared by traditional decocting method (PA) is different from that prepared by modern decocting method (P+A). The present study aimed to investigate the differences in the protective effects of PA and P+A on scopolamine induced cognitive impairment, and to explore its potential mechanism. To assess the protective effect of PA and P+A on cognitive dysfunction, the mice were orally administrated with PA (1.56, 6.24gkg-1•day-1) and P+A (1.56, 6.24gkg-1•day-1) for 26 days before co-treatment with scopolamine (4mgkg-1•day-1, i.p.). The learning and memory abilities of mice were examined by Morris water maze test, and the expressions of proteins related to cholinergic system and synaptic function were detected by the methods of ELISA, real-time PCR and Western blotting. Then, molecular docking technique was used to verify the effect of active compounds in plasma after PA administration on Acetylcholinesterase (AChE) protein. Finally, the Ellman method was used to evaluate the effects of different concentrations of PA, P+A (1 μg/mL-100mg/mL) and the compounds (1-100μM) on AChE activity in vitro. On one hand, in the scopolamine-induced cognitive impairment mouse model, both of PA and P+A could improve the cognitive impairment, while the effect of PA on cognitive amelioration was better than that of P+A. Moreover, PA regulated the cholinergic and synaptic functions by enhancing the concentration of acetylcholine (ACh), the mRNA levels of CHT1, Syn, GAP-43 and PSD-95, and the related proteins (CHT1, VACHT, Syn, GAP-43 and PSD-95), and significantly inhibiting the expression of AChE protein. Meanwhile, P+A only up-regulated the mRNA levels of GAP-43 and PSD-95, increased the expressions of CHT1, VACHT, Syn, GAP-43 and PSD-95 proteins, and inhibited the expression of AChE protein. On the other hand, the in vitro study showed that some compounds including emodin-8-o-β-d-Glucopyranoside, THSG and α-Asarone inhibited AChE protein activity with the IC50 values 3.65μM, 5.42μM and 9.43μM, respectively. These findings demonstrate that both of PA and P+A can ameliorate the cognitive deficits by enhancing cholinergic and synaptic related proteins, while PA has the stronger improvement effect on the cholinergic function, which may be attributed to the compounds including THSG, emodin, emodin-8-O-β-D-glucopyranoside and α-asarone. The present study indicated that PA has more therapeutic potential in the treatment of neurodegenerative diseases such as AD. The results provide the experimental basis for the clinical use of PA.

Dual effect of picolinic acid in the photosynthetic performance of rice plants infected by Bipolaris oryzae

AbstractBrown spot, caused by Bipolaris oryzae, is one of the most important diseases of rice. The non‐host toxin α‐picolinic acid (PA) has great potential to be used to enhance plant resistance against pathogen infection. The present study investigated the effect of spraying PA [0 (control), 1, 3, and 5 mg/mL] on the photosynthetic performance of rice plants (cultivar Metica‐1) infected or not with B. oryzae. Moreover, whether the PA treatment, especially at the highest concentration, could affect brown spot development was also evaluated. The chlorophyll a fluorescence parameters such as variable‐to‐maximum chlorophyll a fluorescence ratio (Fv/Fm), photochemical yield [Y(II)], yield for dissipation by down‐regulation [Y(NPQ)], the yield for non‐regulated dissipation [Y(NO)], and electron transport rate (ETR) as well as the concentration of photosynthetic pigments were determined. Based on the in vitro assay, PA inhibited mycelial growth of B. oryzae in a dose‐dependent manner and conidial germ tube length only decreased at 5 mg PA/mL. Conidia germination was not affected by the PA treatment. Necrotic lesions caused by PA were observed on leaves of non‐inoculated plants at 3 and 5 mg PA/mL. Symptoms of the brown spot were reduced on plants sprayed with 1 and 3 mg PA/mL compared to the control treatment. Brown spot lesions and those originating from PA toxicity overlapped for inoculated plants sprayed with 3 and 5 mg PA/mL. The photochemical performance of non‐inoculated plants was hampered by treatments with 3 and 5 mg PA/mL. Greater concentration of photosynthetic pigments and less impairment on the photosynthetic performance of inoculated plants sprayed with 1 mg PA/mL were noticed based on the values of Fv/Fm, Y(II), Y(NPQ), Y(NO), and ETR compared to inoculated plants non‐sprayed with PA. In conclusion, spraying rice plants with a low concentration of PA could decrease brown spot severity while preserving the photosynthetic capacity of the infected plants. The cellular damage generated by spraying the plants with the highest PA concentration did not favour the infection process of B. oryzae.

Responsive and biocompatible chitosan-phytate microparticles with various morphology for antibacterial activity based on gas-shearing microfluidics

Chitosan microparticles are frequently used for the encapsulation of ingredients, owing to their pH-responsive, renewable, biocompatible and antimicrobial properties. Herein, pH-responsive antibacterial encapsulation carriers in chitosan-phytate (CS-PA) microparticles with various morphologies were prepared by gas-shearing microfluidics. Microparticles sizes were tuned by gas flow rate in production, and the CS and PA concentration significantly dominated the morphology of microparticles. Additionally, microparticles exhibit great storage stability, lyophilizing rehydration performance, pH-responsive behavior, as well as antibacterial and biocompatible effect, indicating that CS-PA microparticles are expected to become an ideal carrier for the actives encapsulation in pharmaceutical, food and cosmetic industries.

Green synthesis of chitosan–phytic acid polymers and nanoparticles

Herein, we aimed to synthesize and characterize chitosan (CS) and phytic acid (PA, CS–PA) polymers and nanoparticles for preparing materials with dye adsorption and drug delivery properties. Based on changes in the solution pH and the molecular weight and concentration of CS and PA, the CS–PA polymers and nanoparticles were prepared using a simple one-step ionic cross-linking protocol. CS–PA nanospheres formed polymers at high CS and PA concentrations, whereas CS–PA nanoparticles were formed at very low concentrations and under suitable pH conditions. Higher concentrations of the material produced denser polymers with a varied nanosphere size. Nanoparticles with different morphologies and sizes were obtained by changing the experimental conditions. Moreover, the self-aggregation of CS molecules in solution was reduced at low concentrations, allowing the easy formation of nanoparticles with regular morphological characteristics with PA. The nanoparticles exhibited good stability under specific conditions. The materials generated here showed promising application in dye adsorption and drug delivery field. This study provides clues for the construction and application of CS-based materials.

Enhancement of electro-optical properties and phase transition temperature of thermotropic liquid crystal 5CB by doping with 4-n-pentylbenzoic acid

ABSTRACT Liquid crystalline materials that have been used in the display industry need to have a wide temperature-range nematic phase while remaining functioning in different climate conditions. In this work, a new binary mixture of thermotropic liquid crystal materials, particularly the nematic phase, has been studied. A widely used material 5CB (4-Cyano-4’−pentyl biphenyl), exhibiting nematics phase, and PA (4-Phenylbenzoic acid) were preferred. Mixtures of different concentrations of 5CB-PA were prepared and investigated using dielectric spectroscopy, phase transition and electro-optical responses techniques. It was found that not only was an improvement to the dielectric anisotropic achieved but also the nematic temperature range extended from 35 ºC to just above 50°C by adding 10 wt.%. On the other hand, the threshold voltage is increased by 10% for the same sample. In addition, elastic constants and response time showed similar behaviours upon increasing the loading concentration of PA, whereas the visco-elastic coefficient significantly declined. All the estimated values for the pure 5CB are in good agreement with the literature. This improvement in the operating temperature range is unique and suggests that the doping can lead to cheap and mass production of a stable liquid crystalline material for their application in the display industry.

A Luminescent Metal‐Organic Framework with Boosted Picric Acid Fluorescence Detection Performance via a Complementary Capture‐Quench Mechanism

AbstractThe strong explosiveness, toxicity and environmental pollution of picric acid make its sensitive detection important. Recently, LMOF materials are showing great potential toward efficient detection of PA. However, hindered by the weak connections between LMOFs and analytes, a feasible fluorescence selectivity and sensitivity to desired compounds by constructed LMOFs remain challenging. Herein, we propose a new strategy by using the innate adsorption ability of MOFs. We choose NDC−Zn, a highly stable LMOF with unique pore structures. The topology of ligands can capture PAs specifically inside the pores and the selectivities are further elevated. PET effects are boosted due to longer and closer contact between ligands and trapped PAs, thus higher sensitivity is also achieved. Besides, a fluorescence enhancement at a visible wavelength was found as the concentration of PA increased, suggesting a potential application of naked‐eye recognition for PA. NDC−Zn exhibited an outstanding detection sensitivity for PA with a quenching constant of 49657 M−1, as well as distinctive fluorescence quenching among 9 nitro explosives. From DFT calculations, the fluorescence quenching mechanisms such as PET and the complexation between H2NDC and PA were supported.

Distribution of Pa in the Atlantic sector of the Southern Ocean: Tracking scavenging during water mass mixing along neutral density surfaces

Dissolved and particulate Protactinium-231 (231Pa) was analyzed for samples from the BONUS GoodHope (BGH) IPY-GEOTRACES cruise in the SE Atlantic sector of the Southern Ocean (36°S-13°E to 57°S-0°, Feb.–Mar. 2008). The inflowing waters from the Atlantic Ocean fuel the Antarctic Circumpolar Current in dissolved 231Pa which is mostly removed from seawater by the biogenic silica produced by diatoms in the Southern Ocean. This scavenging flux of the 231Pa induces a meridional gradient of the 231Pa concentration and of the Th–Pa fractionation factor (FTh/Pa). We propose a first direct estimate of the 231Pa partition coefficient between suspended opal and seawater of about 1.42 ± 0.55 × 106 g/g. This partition coefficient could directly apply to simulate the particulate Pa concentration from the dissolved fraction and the opal concentration. We apply to 231Pa the isopycnal advection-diffusion-scavenging model built for Th isotopes across the ACC. This additional constraint on the model does not modify the isopycnal eddy diffusion estimate of about 1900 ± 180 m2/s at different isopycnal surfaces but suggests a higher particle settling velocity, about 1000 m/y, in the northern part of the ACC than solely derived from Th isotopes. The most different feature is the reduction by half of the estimated uncertainties among the different transport parameters just by the addition of a new constraining parameter. Moreover, this study confirms that 231Pa budget of the Atlantic Sector of Southern Ocean cannot be balanced by considering meridional transport only, and need to consider eastward export to scavenge Pa in the whole area of the Opal Belt.

Development of Polydiphenylamine@Electrochemically Reduced Graphene Oxide Electrode for the D-Penicillamine Sensor from Human Blood Serum Samples Using Amperometry.

D-penicillamine (PA) is a sulfur group-containing drug prescribed for various health issues, but overdoses have adverse effects. Therefore, regular, selective, and sensitive sensing is essential to reduce the need for further treatment. In this study, diphenylamine (DPA) was electropolymerized in an aqueous acidic medium. The PA detection sensitivity, selectivity, and limit of detection were enhanced by electropolymerizing DPA on an electrochemically reduced graphene oxide (ERGO)/glassy carbon (GC) surface. The formation of p-DPA and ERGO was investigated using various techniques. The as-prepared p-DPA@ERGO/GC revealed the excellent redox-active (N-C to N=C) sites of p-DPA. The p-DPA@ERGO/GC electrode exhibited excellent electrochemical sensing ability towards PA determination because of the presence of the -NH-functional moiety and effective interactions with the -SH group of PA. The p-DPA@ERGO/GC exhibited a high surface coverage of 9.23 × 10-12 mol cm-2. The polymer-modified p-DPA@ERGO/GC electrode revealed the amperometric determination of PA concentration from the 1.4 to 541 μM wide range and the detection limit of 0.10 μM. The real-time feasibility of the developed p-DPA@ERGO/GC electrode was tested with a realistic PA finding in human blood serum samples and yielded a good recovery of 97.5-101.0%, confirming the potential suitability in bio-clinical applications.

Characterization of the Microbiome and Host's Metabolites of the Lower Respiratory Tract During Acute Community-Acquired Pneumonia Identifies Potential Novel Markers.

Community-acquired pneumonia (CAP) is one of the most frequently encountered infectious diseases worldwide. Few studies have explored the microbial composition of the lower respiratory tract (LRT) and host metabolites of CAP. We analyzed the microbial composition of the LRT and levels of host metabolites to explore new biomarkers for CAP. Bronchoalveolar lavage fluid (BALF) was collected from 28 CAP patients and 20 healthy individuals. Following centrifugation, BALF pellets were used for amplicon sequencing of a variable region of the bacterial 16S rDNA gene to characterize the microbial composition. Non-targeted metabolomics was used to detect host's metabolites in the supernatant. Compared with healthy individuals, the bacterial alpha diversity in the LRT of CAP patients was significantly lower in CAP patients (p<0.05). On the bacterial genus level, over 20 genera were detected with lower relative abundance (p<0.05), while the relative abundance of Ruminiclostridium-6 was significantly higher in CAP patients. The levels of the host metabolites dimethyldisulfide, choline, pyrimidine, oleic acid and N-acetyl-neuraminic acid were all increased in BALF of CAP patients (p<0.05), while concentrations of lysophosphatidylcholines (LPC (12:0/0:0)) and phosphatidic acid (PA (20:4/2:0)) were decreased (p<0.05). Furthermore, the relative abundance of Parvimonas, Treponema-2, Moraxella, Aggregatibacter, Filifactor, Fusobacterium, Lautropia and Neisseria negatively correlated with concentrations of oleic acid (p<0.05). A negative correlation between the relative abundance of Treponema-2, Moraxella, Filifactor, Fusobacterium and dimethyldisulfide concentrations was also observed (p<0.05). In contrast, the relative abundance of Treponema-2, Moraxella, Filifactor, and Fusobacterium was found to be positively associated with concentrations of LPC (12:0/0:0) and PA (20:4/2:0) (p<0.05). The composition of the LRT microbiome differed between healthy individuals and CAP patients. We propose that some respiratory microbial components and host metabolites are potentially novel diagnostic markers of CAP.