Free Chain Research Articles

Chemically Modified Biopolymers for the Formation of Biomedical Hydrogels.

Biopolymers are natural polymers sourced from plants and animals, which include a variety of polysaccharides and polypeptides. The inclusion of biopolymers into biomedical hydrogels is of great interest because of their inherent biochemical and biophysical properties, such as cellular adhesion, degradation, and viscoelasticity. The objective of this Review is to provide a detailed overview of the design and development of biopolymer hydrogels for biomedical applications, with an emphasis on biopolymer chemical modifications and cross-linking methods. First, the fundamentals of biopolymers and chemical conjugation methods to introduce cross-linking groups are described. Cross-linking methods to form biopolymer networks are then discussed in detail, including (i) covalent cross-linking (e.g., free radical chain polymerization, click cross-linking, cross-linking due to oxidation of phenolic groups), (ii) dynamic covalent cross-linking (e.g., Schiff base formation, disulfide formation, reversible Diels-Alder reactions), and (iii) physical cross-linking (e.g., guest-host interactions, hydrogen bonding, metal-ligand coordination, grafted biopolymers). Finally, recent advances in the use of chemically modified biopolymer hydrogels for the biofabrication of tissue scaffolds, therapeutic delivery, tissue adhesives and sealants, as well as the formation of interpenetrating network biopolymer hydrogels, are highlighted.

Synergistic Inhibitory Effect of Free Radical Scavenger/Inorganic Salt Compound Inhibitor on Spontaneous Combustion of Coal

ABSTRACT From the aspects of isolating oxygen, lowering temperature and terminating free radical chain reaction, an inorganic salt inhibitor and a radical scavenger were combined to form a compound inhibitor for preventing of coal spontaneous combustion. A long-flame coal with easy self-ignition was chosen to study the inhibitory performance of different inhibitors using inhibition performance tests and by characterizing reactive functional groups and performing thermal analysis. The experimental results show that the compound inhibitor has a coordinated inhibitory effect throughout the whole process of coal spontaneous combustion, with physical and chemical double inhibition effect. Compared with the raw coal, the amount of CO released from the coal sample treated by the compound inhibitor was reduced by 88.7% at 128°C, and the inhibition rate reached 82.5% at 100°C. The inhibition ratio is higher than 80% during the initial weight loss stage and the oxygen absorption and weight increase stage. The compound inhibitor plays an inhibitory role by reducing the contents of hydroxyl, methyl, methylene groups and active components containing carbonyl groups in the coal, wherein, the relative content of a carbonyl compounds decreased obviously. During the initial weight loss stage, the water retention due to inorganic salts physically isolated oxygen and cooled the coal. During the oxygen adsorption and mass gain stage, free radicals were released from the compound inhibitor and captured both oxygen free radicals and carbon free radicals via chemical inhibition. N,N-Dibenzylhydroxylamine (DBHA) contains multiple absorption sites that can simultaneously capture multiple free radicals in coal. Butylated hydroxyl toluene (BHT) reacts with free oxygen-containing functional groups to form stable compounds, which interrupts the formation paths for ketones and aldehydes. Moreover, the inhibition mechanism of the compound inhibitor on coal spontaneous combustion was also explored.

Cardiac Amyloidosis: Internist and Cardiologist Insight

Cardiac amyloidosis (amyloid cardiomyopathy) is a disease damage to the heart caused by extracellular amyloid deposition. In some cases, there may be local damage to the structures of the heart, for example, the atria; more often, heart damage is part of a systemic (generalized) pathology. Depending on the amyloid precursor protein, 36 types of amyloidosis are described, among which hereditary and acquired forms are distinguished. Cardiac amyloidosis is diagnosed 1) in the case of the amyloid infiltration in the myocardial bioptates or 2) in the case of non-cardiac amyloid deposition and the left ventricular wall thickening >12 mm without arterial hypertension and other reasons. The heart is most often affected in AL-, ATTR-, AA-, AANF-types of amyloidosis. Cardiac amyloidosis should be considered in patients with a heart failure with an unclear etiology, especially with preserved left ventricular ejection fraction, refractory to treatment, with proteinuria and CKD 4-5, in patients with idiopathic atrial fibrillation and conduction disturbances, in patients with left ventricular wall thickening of unclear etiology, low ECG voltage, unexplained arterial hypotension and pulmonary hypertension. Screening for cardiac amyloidosis should include non-invasive methods such as electrophoresis and immunofixation of blood and urine proteins, the free light lambda and kappa chains of immunoglobulins, 99Tc-DPD scintigraphy, genetic testing (if hereditary variants of amyloidosis are suspected), as well as a histological examination of biopsy samples stained with Congo red and polarizing microscopy.

A New Perspective of the Chemistry and Kinetics of Inactivation of COVID -19 Coronavirus Aerosols

In this paper we present a new approach to the mechanism of inactivation of enveloped virus aerosols. The analysis is in terms of oxidation of the lipid bilayer of the viral envelope through a free radical chain reaction. The rate kinetics of the process for various enveloped viruses have been compared and the indications are that the inactivations are closely related. Promoting virus inactivation with UV light is briefly reviewed and discussed as an extension of the chain reaction mechanism, which with physicochemical analyses give insights into the process and of reaction complexities. An outline of a practical method of achieving a 3-log10 level of deactivation in 1 min is described with purified air being returned to healthcare environments.

Generic transport formula for a system driven by Markovian reservoirs

We present a generic, compact formula for the current flowing in interacting and non-interacting systems which are driven out-of-equilibrium by biased reservoirs described by Lindblad jump operators. We show that, in the limit of high temperature and chemical potential, our formula is equivalent to the well-known Meir-Wingreen formula, which describes the current flowing through a system connected to fermionic baths, therefore bridging the gap between the two formalisms. Our formulation gives a systematic way to address the transport properties of correlated systems strongly driven out of equilibrium. As an illustration, we provide explicit calculations of the current in three cases : {\it i)} a single-site impurity {\it ii)} a free fermionic chain {\it iii)} a fermionic chain with loss/gain terms along the chain. In this last case, we find that the current across the system has the same behavior for loss or gain terms and depends on the loss/gain rate in a non-monotonic way.

Nutritional Composition, Antioxidant Activity and Common Phytochemicals of Selected BARI Mango Varieties and Commercial Cultivar Langra

The present study sought to explore the nutritional composition, bioactive phytochemicals and antioxidant activity of BARI mango-4, BARI mango-6 and Langra cultivar. The total phenolic (TPH), vitamin C, total carotene, ß-carotene content and antioxidant activity of the mangos were determined by 1,1- diphenyl-2picryl hydrazyl (DPPH) scavenging and reducing power assays (RPA). Phenolic compounds were assessed using high-performance liquid chromatography coupled with a photodiode array detector and auto sampler. Results revealed that moisture, TSS, pH, total acidity, reducing, total sugar and energy of the BARI mango-4 and BARI mango-6 were 76.54 and 75.24 %, 17.10°B and 21.20°B, 4.90 and 5.01, 0.49 and 0.50 %, 3.90 and 4.54 %, 11.20 and 13.46 % and 4028.06 and 3950.27 cal/g respectively whereas the Langra cultivar remained 76.33 %, 17.63°B, 4.25, 0.63 %, 2.79 %, 9.79 % % and 3871.28 cal/g respectively. Phytochemicals especially TPH, ascorbic acid, total flavonoid (TF), total carotenoid (TC), ß-carotene and total anthocyanin content (TAC) of the BARI mango-4 and BARI mango-6 were 20.53 and 20.67 mg GAE/g, 39.98 and 26.26 mg/100 g, 3.14 mg and 2.87 QE/g, 76.38 and 81.33 mg/100 g, 28.17 and 65.84 µg/100 g and 1.67 and 11.69 mg/100 respectively whereas the Langra contained 19.90 mg GAE/g, 25.53 mg/100g, 1.38 mg QE/g, 4.21 mg/100 g, 31.00 µg/100 g and18.22 mg/100 g respectively. In case of antioxidant activities total antioxidant capacity, DPPH radical scavenging activity, reducing power capacity (RPC), metal chelating capacity (MCC), Nitric oxide (NO) free radical scavenging activity and IC50 of the BARI mango-4 and BARI mango-6 were 229.00 and 309.00 µg of ascorbic acid/mg of extract, 96.84 and 94.73 %, 12.20 and 9.71 µg/mL, 157.36 and 132.89 %, 61.74 and 72.65 µg/mL and 0.59 and 0.71 µg/mL respectively whereas the Langra cultivar contained 194.25 µg of ascorbic acid/mg of extract, 87.94 %, 2.54 µg/mL, 177.80 %, 53.74 µg/mL and 25.11 µg/mL respectively. The results indicate that BARI mango-4 and BARI mango-6 exhibited rich source of TPH, TC, ß-carotene, ascorbic acid, TA, TAC and NO free radical scavenging activity whereas the Langra is the rich source of MCC and anthocyanin content. Phenolic acids were leading agent in BARI mango-4 and BARI mango-6. Moreover, BARI mango-4 and BARI mango-6 extract had a great potential to fight free radical chain reactions and for usage in therapeutic applications.

Tuning Selectivities in Gas Separation Membranes Based on Polymer-Grafted Nanoparticles.

Polymer membranes are critical to many sustainability applications that require the size-based separation of gas mixtures. Despite their ubiquity, there is a continuing need to selectively affect the transport of different mixture components while enhancing mechanical strength and hindering aging. Polymer-grafted nanoparticles (GNPs) have recently been explored in the context of gas separations. Membranes made from pure GNPs have higher gas permeability and lower selectivity relative to the neat polymer because they have increased mean free volume. Going beyond this ability to manipulate the mean free volume by grafting chains to a nanoparticle, the conceptual advance of the present work is our finding that GNPs are spatially heterogeneous transport media, with this free volume distribution being easily manipulated by the addition of free polymer. In particular, adding a small amount of appropriately chosen free polymer can increase the membrane gas selectivity by up to two orders of magnitude while only moderately reducing small gas permeability. Added short free chains, which are homogeneously distributed in the polymer layer of the GNP, reduce the permeability of all gases but yield no dramatic increases in selectivity. In contrast, free chains with length comparable to the grafts, which populate the interstitial pockets between GNPs, preferentially hinder the transport of the larger gas and thus result in large selectivity increases. This work thus establishes that we can favorably manipulate the selective gas transport properties of GNP membranes through the entropic effects associated with the addition of free chains.

Investigation of a Low-Toxicity Energetic Binder for a Solid Propellant: Curing, Microstructures, and Performance.

In this work, a promising propellant binder using the energetic branched glycidyl azide polymer (B-GAP) as a matrix and the low-toxic dimer acid diisocyanate (DDI) as a curing agent was prepared, under the catalysis of dibutyl tin dilaurate. The curing kinetics considering the thermal diffusion effect and the reaction endpoint of B-GAP/DDI were investigated by the thermal analysis method and a newly proposed variance method, respectively. Moreover, the buildup of microstructures during curing and the tensile and dynamic mechanical performance of this binder were respectively explored. Results show that there exists an obvious induction period in the beginning of the curing reaction, and the autocatalytic model shows that thermal diffusion can effectively describe the curing process. Shore A hardness of sample stabilizes around 40.78 in the end of curing, and the reaction endpoint of B-GAP/DDI is in the time range of 156–168 h. There exist cross-linking, suspension, and free chains during the whole curing process, and the cross-linking density of the binder reaches approximately 4.0 × 10–4 mol·cm–3 when the curing completes. Hydrogen bonding (H-bond) is found to be a strong binder: 53.3% of the carbonyls participates in forming the H-bond. Furthermore, this binder has better mechanical performance and lower glass-transition temperature than the GAP/N100 binder.

Synthesis, Structure, Hydrodynamics and Thermoresponsiveness of Graft Copolymer with Aromatic Polyester Backbone at Poly(2-isopropyl-2-oxazoline) Side Chains.

New thermoresponsive graft copolymers with an aromatic polyester backbone and poly(2-isopropyl-2-oxazoline) (PiPrOx) side chains are synthesized and characterized by NMR and GPC. The grafting density of side chains is 0.49. The molar masses of the graft-copolymer, its backbone, side chains, and the modeling poly-2-isopropyl-2-oxaziline are 74,000, 19,000, 4300, and 16,600 g·mol−1, respectively. Their conformational properties in nitropropane as well as thermoresponsiveness in aqueous solutions are studied and compared with that of free side chains, i.e., linear PiPrOx with a hydrophobic terminal group. In nitropropane, the graft-copolymer adopts conformation of a 13-arm star with a core of a collapsed main chain and a PiPrOx corona. Similarly, a linear PiPrOx chain protects its bulky terminal group by wrapping around it in a selective solvent. In aqueous solutions at low temperatures, graft copolymers form aggregates due to interaction of hydrophobic backbones, which contrasts to molecular solutions of the model linear PiPrOx. The lower critical solution temperature (LCST) for the graft copolymer is around 20 °C. The phase separation temperatures of the copolymer solution were lower than that of the linear chain counterpart, decreasing with concentration for both polymers.

Fetal Hemoglobin Rescues Ineffective Erythropoiesis in Sickle Cell Disease

Sickle cell disease (SCD) is an autosomal hereditary recessive disorder caused by a point mutation in the β globin gene resulting in a Glu-to-Val substitution at the 6th position of the β globin protein. The resulting abnormal hemoglobin (HbS) polymerizes under hypoxic conditions driving red blood cell (RBC) sickling (Pauling et al., 1949). While pathobiology of circulating RBCs has been extensively analyzed in SCD, erythropoiesis is surprisingly poorly documented. In β-thalassemia, ineffective erythropoiesis is characterized by high levels of apoptotic erythroblasts during the late stages of terminal differentiation, due to an accumulation of free β-globin chains (Arlet et al., 2016). Ineffective erythropoiesis is the major cause of anemia in β-thalassemia patients. In contrast, a marked decrease in life span of circulating red cells, a feature of sickle red cells, is considered to be the major determinant of chronic anemia in SCD. It is generally surmised that ineffective erythropoiesis contributes little to anemia. The bone marrow environment has been well documented to be hypoxic (0.1 to 6% O2) (Mantel et al., 2015). As hypoxia induces HbS polymerization, we hypothesized that cell death may occur in vivo because of HbS polymer formation in the late stages of differentiation characterized by high intracellular hemoglobin concentration. In the present study, using both in vitro and in vivo derived human erythroblasts we assessed the extent of ineffective erythropoiesis in SCD. We explored the mechanistic basis of the ineffective erythropoiesis in SCD using biochemical, cellular and imaging techniques. In vitro erythroid differentiation using CD34+ cells isolated from SCD patients and from healthy donors was performed. A 2-phase erythroid differentiation protocol was used and cultures were performed at two different oxygen conditions, i.e. normoxia and partial hypoxia (5% O2). We found that hypoxia induces cell death of sickle erythroblasts starting at the polychromatic stage, positively selecting cells with high levels of fetal hemoglobin (HbF). This inference was supported by flow cytometry data showing higher percentages of dead cells within the non-F-cell population as compared to the F-cell population for SCD cells. Moreover, SCD dead cells showed higher levels of chaperon protein HSP70 in the cytoplasm than live cells, while no difference was detected between both subpopulations for control cells, suggesting that cell death of SCD erythroblasts was probably due to HSP70 cytoplasmic sequestration. This was supported by western-blot experiments showing less HSP70 in the nucleus of SCD erythroblasts under hypoxia, associated with decreased levels of GATA-1. At the molecular level, HSP70 was co-immunoprecipitated with HbS under hypoxia indicating that both proteins were in the same complex and suggesting interaction between HSP70 and HbS polymers in the cyotplasm. Importantly, we confirm these results in vivo by showing that in bone marrow of SCD patients (n = 5) cell loss occurs during terminal erythroid differentiation, with a significant drop in the cell count between the polychromatic and the orthochromatic stages (Figure 1). In order to specifically address the role of HbF in cell survival, we used a CRISPR-Cas9 approach to mimic the effect of hereditary persistence of fetal hemoglobin (HPFH). CD34+ cells were transfected either with a gRNA targeting the LRF binding site (-197) or a gRNA targeting an unrelated locus (AAVS1) (Weber, Frati, et al. 2020). As expected, the disruption of the LRF binding site resulted in HbF induction as shown by higher %F-cells compared to AAVS1 control. These higher levels of F-cells resulted in decreased apoptosis, under both normoxic and hypoxic conditions, clearly demonstrating the positive and selective effect of HbF on SCD cell survival (Figure 2). In summary, our study shows that HbF has a dual beneficial effect in SCD by conferring a preferential survival of F-cells in the circulation and by decreasing ineffective erythropoiesis. These findings thus bring new insights into the role of HbF in modulating clinical severity of anemia in SCD by both regulating red cell production and red cell destruction. Disclosures No relevant conflicts of interest to declare.

The frequency of cardiac amyloidosis in 182 patients receiving carpal tunnel release surgery

Abstract Introduction Retrospective studies have suggested that a significant proportion of patients with cardiac amyloidosis received surgical treatment for carpal tunnel syndrome (CTS) 5–10 years before diagnosis of their cardiac condition. So far, one cross-sectional study has investigated the presence of localized and systemic amyloidosis in 98 patients undergoing carpal tunnel release surgery (CTRS). Ten percent were shown to have amyloid deposits in the carpal tunnel while two had cardiac involvement caused by either AL amyloidosis or wild-type transthyretin amyloidosis (ATTR). Purpose To investigate the prevalence of cardiac amyloidosis among unselected and consecutive patients undergoing CTRS. Methods Tissue samples from the carpal tunnel of 182 CTRS patients were stained with Congo Red. Amyloid positive samples were subtyped by immunoelectron microscopy and mass spectrometry. Amyloid positive patients underwent investigations for cardiac amyloidosis including ECG-recording, echocardiography and strain imaging, cardiac magnetic resonance imaging and whole-body scintigraphy (99m-tc-DPD). Genetic investigation of the gene for TTR was performed in patients with ATTR amyloidosis or an undetermined subtype. Patients were also investigated by measurements of NT-proBNP, troponins, immunoglobulins, M-protein in serum and urine, and free light kappa and lambda chains in serum. Results In total, 16% (29/182) of the patients had amyloid positive biopsies. They were significantly older than amyloid negative patients (73 years vs 53 years, p<0.001). The prevalence of males was significantly higher in the amyloid positive group (66% vs 25%, p<0.001). The presence of bilateral CTS was not associated with amyloid deposits. The subtype of amyloid was shown to be (a) ATTR in 86% (n=25) of patients, (b) localized light-chain amyloidosis in 3% (n=1), and (c) fibrinogen alpha amyloidosis in 3% (n=1), while the amount of tissue did not allow subtyping in 7% (n=2). All ATTR patients had a normal genetic investigation. So far, 24 of the 29 amyloid positive patients have completed all clinical investigations and no one fulfilled diagnostic criteria of cardiac amyloidosis. Conclusion A significant number of CTRS patients, (14%), had wild-type ATTR amyloidosis confined to the carpal tunnel. None of these had cardiac involvement. These findings were different from the results in the previous prospective study and were likely to be explained by differences in the patient cohorts investigated. We investigated unselected patients in contrast to the highly selected cohort in the previous study. Based on the findings in the current study the proportion of CTRS patients with localized amyloidosis who may develop systemic disease is unknown. Therefore, it is necessary to perform long term follow-up of these patients before routine investigations for amyloidosis may be recommended. Funding Acknowledgement Type of funding source: Private company. Main funding source(s): Financial support was obtained by an unrestricted research grant from Alnylam Pharmaceuticals

LIGHT CHAIN MULTIPLE MYELOMA: A CASE REPORT

Light chain multiple myeloma (LCMM) initiates approximately 15 percentage of patients with multiple myeloma (MM). It has a lower prognosis when compared with the variant immunoglobulin (Ig) G or IgA. We report a rare case on Light chain multiple myeloma in 49-year-old male patient who presented with acute kidney injury, hypercalcemia. histopathology examination was found to be plasmacytoma, kappa restricted; and free kappa lamda chain in urine and serum was found to be greater. Bone pain and renal dysfunction were the most common prevalent initial signs and symptoms while extramedullary disease (EMD) was later acquired during disease. Bortezomib demonstrated superior efficacy over nonbortezomib in LCMM patients.

Unanchored Ubiquitin Chains, Revisited.

The small modifier protein, ubiquitin, holds a special place in eukaryotic biology because of its myriad post-translational effects that control normal cellular processes and are implicated in various diseases. By being covalently conjugated onto other proteins, ubiquitin changes their interaction landscape - fostering new interactions as well as inhibiting others - and ultimately deciding the fate of its substrates and controlling pathways that span most cell physiology. Ubiquitin can be attached onto other proteins as a monomer or as a poly-ubiquitin chain of diverse structural topologies. Among the types of poly-ubiquitin species generated are ones detached from another substrate - comprising solely ubiquitin as their constituent - referred to as unanchored, or free chains. Considered to be toxic byproducts, these species have recently emerged to have specific physiological functions in immune pathways and during cell stress. Free chains also do not appear to be detrimental to multi-cellular organisms; they can be active members of the ubiquitination process, rather than corollary species awaiting disassembly into mono-ubiquitin. Here, we summarize past and recent studies on unanchored ubiquitin chains, paying special attention to their emerging roles as second messengers in several signaling pathways. These investigations paint complex and flexible outcomes for free ubiquitin chains, and present a revised model of unanchored poly-ubiquitin biology that is in need of additional investigation.

Mechanisms of Phorbol Ester Toxicity, Determined by Molecular Modelling

Phorbol esters are toxic phytochemicals, whose main biological target is protein kinase C. They bind irreversibly to the protein, causing cell damage. Using computer modelling, we have determined, for the first time, features and mechanisms that lead to the toxicity of phorbol esters.
 Protein kinase C – delta (PKC-δ) was used as a target protein in computational docking studies with phorbol esters that differ in molecular structure. Binding conformations and stability of ester linkages were analyzed to evaluate their relationship with experimental observations. Results show that an active phorbol ester must exhibit two features: interaction with specific amino acid residues at the binding site and covering the area with a hydrophobic surface. Toxicity of an active phorbol ester is inversely proportional to the intrinsic reactivity of the ester linkage. Phorbol esters bearing free acid chains can directly activate PKC-δ but jatropha phorbol esters are restricted by their acid-moiety ring formations, suggesting similar mechanism of interaction with other phorbol-ester protein targets.

Polymer brushes in pores by ATRP: Monte Carlo simulations

Growth and properties of polymer brushes anchored to the surface of cylindrical and spherical pores were studied using Monte Carlo computer simulations. Grafting density of studied dense brushes was higher than the polymer coil overlap density. The properties of brushes were “realistic” i.e. their dispersity depended on synthetic conditions such as the polymerization rate and the pore radius. The effect of surface curvature on properties of the brushes was analyzed. Brush relaxation was studied to determine true equilibrium chain size and polymer concentration profile, especially for the fast polymerization. End-to-end distance of chains of similar lengths increased with increasing pore radius and depended on the polymerization rate and brush average molecular weight. Distribution of free chain ends approximately followed polymer distribution in the brush with a maximum close to the pore surface.

Assembly of Polymer-Grafted Nanoparticles in Polymer Matrices.

Leibler pioneered the idea that long enough matrix polymers of length P will spontaneously dewet a chemically identical polymer layer, comprising chains of length N, densely end-grafted to a flat surface ("brush"). This entropically driven idea is routinely used to explain experiments in which 10-20 nm diameter nanoparticles (NPs) densely grafted with polymer chains are found to phase separate from chemically identical melts for P/N ≳4. At lower grafting densities, these effects are also thought to underpin the self-assembly of grafted NPs into a variety of structures. To explore the validity of this picture, we conducted large-scale molecular dynamics simulations of grafted NPs in a chemically identical polymer melt. For the NPs we consider, in the ≈5 nm diameter range, we find no phase separation even for P/N = 10 in the absence of attractions. Instead, we find behavior that more closely parallels experiments when all of the chain monomers are equally attractive to each other but repel the NPs. Our results thus imply that experimental situations investigated to date are dominated by the surfactancy of the NPs, which is driven by the chemical mismatch between the inorganic core and the organic ligands (the graft and free chains are chemically identical). Entropic effects, that is, the translational entropy of the NPs and the matrix, the entropy of mixing of the grafts and the matrix, and the conformational entropy of the chains appear to thus have a second-order effect even in the context of these model systems.

Antioxidant activities and mechanisms of polysaccharides.

Polysaccharide, as one of the effective components of traditional Chinese medicine, has the activities of anti-oxidation, anti-virus, improving immunity and so on. Chinese herbal polysaccharides have a wide range of sources. It is found that polysaccharides in many plants and microorganisms have significant antioxidant effects, mainly through the endogenous antioxidant stress Nrf2/ARE pathway to regulate the expression of downstream antioxidant enzymes. These antioxidant enzymes can further block the free radical chain reaction, thus reducing the generation of free radicals. Secondly, by inhibiting the expression of iNOS mRNA and reducing NO production, it can significantly increase the antioxidant capacity and reduce oxidative stress injury. Polysaccharides are rich in natural resources, their multi-channel, multi-target, multi-effect, and other characteristics have made great progress in antioxidants.

Bacteria-derived long chain fatty acid exhibits anti-inflammatory properties in colitis

ObjectiveData from clinical research suggest that certain probiotic bacterial strains have the potential to modulate colonic inflammation. Nonetheless, these data differ between studies due to the probiotic bacterial strains used...

Grafting with RAFT-gRAFT Strategies to Prepare Hybrid Nanocarriers with Core-shell Architecture.

Stimuli-responsive polymer materials are used in smart nanocarriers to provide the stimuli-actuated mechanical and chemical changes that modulate cargo delivery. To take full advantage of the potential of stimuli-responsive polymers for controlled delivery applications, these have been grafted to the surface of mesoporous silica particles (MSNs), which are mechanically robust, have very large surface areas and available pore volumes, uniform and tunable pore sizes and a large diversity of surface functionalization options. Here, we explore the impact of different RAFT-based grafting strategies on the amount of a pH-responsive polymer incorporated in the shell of MSNs. Using a “grafting to” (gRAFT-to) approach we studied the effect of polymer chain size on the amount of polymer in the shell. This was compared with the results obtained with a “grafting from” (gRAFT-from) approach, which yield slightly better polymer incorporation values. These two traditional grafting methods yield relatively limited amounts of polymer incorporation, due to steric hindrance between free chains in “grafting to” and to termination reactions between growing chains in “grafting from.” To increase the amount of polymer in the nanocarrier shell, we developed two strategies to improve the “grafting from” process. In the first, we added a cross-linking agent (gRAFT-cross) to limit the mobility of the growing polymer and thus decrease termination reactions at the MSN surface. On the second, we tested a hybrid grafting process (gRAFT-hybrid) where we added MSNs functionalized with chain transfer agent to the reaction media containing monomer and growing free polymer chains. Our results show that both modifications yield a significative increase in the amount of grafted polymer.

Non-Hermitian quantum impurity systems in and out of equilibrium: Noninteracting case

We provide systematic analysis on a non-Hermitian PT -symmetric quantum impurity system both in and out of equilibrium, based on exact computations. In order to understand the interplay between non-Hermiticity and Kondo physics, we focus on a prototypical noninteracting impurity system, the resonant level model, with complex coupling constants. Explicitly constructing biorthogonal basis, we study its thermodynamic properties as well as the Loschmidt echo starting from the initially disconnected two free fermion chains. Remarkably, we observe the universal crossover physics in the Loschmidt echo, both in the PT broken and unbroken regimes. We also find that the ground state quantities we compute in the PT broken regime can be obtained by analytic continuation. It turns out that Kondo screening ceases to exist in the PT broken regime, which was also previously predicted in the non-hermitian Kondo model. All the analytical results are corroborated against biorthogonal free fermion numerics.