Degree Of Branching Research Articles

In Vivo Pravastatin Treatment Reverses Hypercholesterolemia Induced Mitochondria-Associated Membranes Contact Sites, Foam Cell Formation, and Phagocytosis in Macrophages.

Statins are successful drugs used to treat hypercholesterolemia, a primary cause of atherosclerosis. In this work, we investigated how hypercholesterolemia and pravastatin treatment impact macrophage and mitochondria functions, the key cell involved in atherogenesis. By comparing bone marrow-derived macrophages (BMDM) of wild-type (WT) and LDL receptor knockout (LDLr−/−) mice, we observed hypercholesterolemia increased the number of contact sites at mitochondria-associated endoplasmic reticulum (ER) membranes (MAMs), enhanced mitochondrial hydrogen peroxide release, altered the gene expression of inflammatory markers, and increased oxidized LDL (ox-LDL) uptake and phagocytic activity. Three months of in vivo pravastatin treatment of LDLr−/− mice reversed the number of contact sites at the MAM, ox-LDL uptake, and phagocytosis in LDLr−/− BMDM. Additionally, pravastatin increased BMDM mitochondrial network branching. In peritoneal macrophages (PMs), hypercholesterolemia did not change MAM stability, but stimulated hydrogen peroxide production and modulated gene expression of pro- and anti-inflammatory markers. It also increased mitochondrial branching degree and had no effects on ox-LDL uptake and phagocytosis in PM. Pravastatin treatment increased superoxide anion production and changed inflammation-related gene expression in LDLr−/− PM. In addition, pravastatin increased markedly the expression of the mitochondrial dynamics-related genes Mfn2 and Fis1 in both macrophages. In summary, our results show that hypercholesterolemia and pravastatin treatment affect macrophage mitochondria network structure as well as their interaction with the endoplasmic reticulum (ER). These effects impact on macrophage conversion rates to foam cell and macrophage phagocytic capacity. These findings associate MAM stability changes with known mechanisms involved in atherosclerosis progression and resolution.

Insights into the micro-structures and reactive behaviors of coal vitrinite and inertinite macerals with CuFe2O4 in chemical looping combustion

As a carbon capture technology, chemical looping combustion (CLC) can realize efficient coal utilization, for which understanding micro-structures and reactive behaviors of coal is highly demanded. This work reveals the relative behaviors of vitrinite and inertinite macerals according to chemical bonding fracture during CuFe2O4 based CLC by thermo-gravimetric analysis and fixed bed reactor. It was found that CLC process reduces the interlayer spacing of the aromatic layers, and increases the interlayer defects of the aromatic rings and the condensation of the aromatic rings. The relative content of C–C/C–H of chars significantly reduced, and the content of C-O significantly increased during CLC. The introduction of CuFe2O4 OCs is more conducive to promote the conversion of C–C/C–H functional groups in coal to C-O. Vitrinite has higher reactivity in CLC, mainly derived from higher degree of side chain branching of alkanes and fatty hydrocarbon bonds.

A glucomannogalactan from Pleurotus geesteranus: Structural characterization, chain conformation and immunological effect

A water-soluble glucomannogalactan was isolated from P. geesteranus fruit bodies by hot water extraction and column chromatography method. The structure, chain conformation and immune effect of PGP-1c (20.9 kDa) were investigated comprehensively based on high purity and neutral sugar content (94.7 ± 0.5%). Confirmed by monosaccharide composition, methylation and NMR analysis, PGP-1c was composed of unsubstituted (1,6-α-Gal and 1,6-α-3-OMe-Gal) and monosubstituted (1,2,6-α-Gal and 1,2,6-α-3-OMe-Gal) galactose units in the backbone through α-(1 → 6) glycosidic bonds and the possible branches that a long-branched chain composed of →3)-Glc-(1 → Man and a few fucoses were connected at the O-2 of galactose with a branching degree of 48%. Through the conformational behavior of the molecular chain, it was observed that PGP-1c might have a long-branched or stacked macromolecular network caused by O-CH3 groups. Moreover, PGP-1c could promote the secretion of NO and cytokines significantly in a dose-dependent manner, which indicated a good immune-enhancing effect.

Impacts of physical-chemical property of polyethylene on depolymerization and biodegradation in yellow and dark mealworms with high purity microplastics

Yellow and dark mealworms (Tenebrio molitor and Tenebrio obscurus) biodegrade commercial polyethylene (PE) materials at a high rate. We examined the impact of physical and chemical properties on biodegradation using high purity microplastics (MPs). These included high-density polyethylene (HDPE), low-density polyethylene (LDPE), and linear low-density polyethylene (LLDPE), all with different weight average molecular weights (Mw) and different crystallinity degrees in T. molitor and T. obscurus larvae. The biodegradation extent in the two mealworms was similar but strongly depended on the polymer type in sequence, since LDPE > LLDPE> HDPE (with respective Mw of 222.5, 110.5 and 182 kDa). When LDPE MPs with Mw of 0.84, 6.4 and 106.8 kDa and HDPE with Mw of 52, 105 and 132.7 kDa were tested, the PE MPs with lower Mw showed a greater extent of depolymerization. The results of dominance analysis indicated that less branching structure and higher crystallinity degree negatively impacted depolymerization and biodegradation. Py-GC/MS analysis confirmed the breaking of the macromolecule backbone as well as the formation of oxidized functional groups after all the tested PE materials passed through the mealworm intestine. The results demonstrated that molecular weight, PE type, branching, and crystallinity degree significantly affect the biodegradation capability of PE by the mealworms, and possibly by other biological systems as well.

Дендримеры PAMAM и перспективы их применения в медицине

Development of drug delivery systems based on branched biocompatible polymers is one of the most promising areas of modern nanopharmaceutics. Researchers have been exploring this area several decades now, and the results of their efforts quickly find their way into production. Dendrimers, a new class of universal synthetic polymers with a highly functional surface, have a number of unique properties: constant size, high degree of branching, multivalence, solubility in water, definite molecular weight, internal cavities. With the release of VivaSol gel, the first dendrimer-based commercialized product, the "model range" of dendrimer carriers has grown significantly. Poly(amide-amine) (PAMAM) dendrimers, which consist of an alkyldiamine core and tertiary amine branches, are believed to be among the most promising compounds that can be used in the development of the new generation drugs. However, they were kept out of the list of clinically acceptable compounds for a long time because of their toxicity, unclear behavior in living systems and pharmacokinetic profile, as well the difficulties associated with establishing a therapeutic dose. This review presents basic information about PAMAM dendrimers and attempts to assess the prospects of their application in treatment of various diseases, including COVID-19.

Selective branch formation in ethylene polymerization to access precise ethylene-propylene copolymers

Polyolefins with branches produced by ethylene alone via chain walking are highly desired in industry. Selective branch formation from uncontrolled chain walking is a long-standing challenge to generate exclusively branched polyolefins, however. Here we report such desirable microstructures in ethylene polymerization by using sterically constrained α-diimine nickel(II)/palladium(II) catalysts at 30 °C–90 °C that fall into industrial conditions. Branched polyethylenes with exclusive branch pattern of methyl branches (99%) and notably selective branch distribution of 1,4-Me2 unit (86%) can be generated. The ultrahigh degree of branching (>200 Me/1000 C) enables the well-defined product to mimic ethylene-propylene copolymers. More interestingly, branch distribution is predictable and computable by using a simple statistical model of p(1-p)n (p: the probability of branch formation). Mechanistic insights into the branch formation including branch pattern and branch distribution by an in-depth density functional theory (DFT) calculation are elucidated.

Construction of a Homogeneous Enzyme-Free Autocatalytic Nucleic Acid Machinery for High-Performance Intracellular Imaging of MicroRNA

Construction of a Homogeneous Enzyme-Free Autocatalytic Nucleic Acid Machinery for High-Performance Intracellular Imaging of MicroRNA

Effects of warming on starch structure, rice flour pasting property, and cooked rice texture in a double rice cropping system

AbstractBackground and objectivesClimate warming has significant effects on rice quality. However, the effects of warming on starch structure, rice flour pasting properties, and cooked rice texture are unclear in double rice cropping systems. Therefore, a free‐air temperature increase experiment was conducted with two indica rice cultivars. The objectives of this study were to explore the changes in rice flour pasting properties and cooked rice texture under warming conditions and their relationships with starch structures.FindingsUnder warming conditions, rice starch had a lower amylose content (Peak 3) and proportion of long amylopectin branch chains (B3 chains) but a higher proportion of short amylopectin branch chains (A chains and B1 chains), amylopectin branching degree, relative crystallinity, ratio of 1045/1022 cm−1, and swelling power. Compared to the control treatment, warming significantly increased the peak viscosity, breakdown, and pasting temperature but decreased the setback of rice flour. Moreover, the hardness of cooked rice was significantly decreased, while its stickiness was significantly increased under warming conditions.ConclusionsThe changes in starch molecular structures resulted in lower hardness and setback but a higher stickiness, peak viscosity, breakdown, and pasting temperature of cooked rice or rice flour, which means better eating quality and worse cooking quality of double‐cropped indica rice under climate warming conditions.Significance and noveltyThese findings are expected to provide important information for improving rice cooking and eating quality and developing the rice industry under future climate warming conditions.

Structural, physicochemical and long-term retrogradation properties of wheat starch treated using transglucosidase

To reduce the wheat-flour-based food texture and flavor deterioration caused by starch retrogradation, herein wheat starch, the most ingredient in wheat flour, was modified by transglucosidase to delay long-term retrogradation of wheat starch. The study proposed promising data of transglucosidase-treated starch about structure, crystallinity and retrogradation kinetics. Structural properties showed that transglucosidase treatment shortened the average chain length from 19.49 to 16.10 and induced the dominance of amorphous state. Moreover, branching degree increased from 14.11% to 17.97% after transglucosidase treatment, resulting in higher water mobility. Amylose content increased from 25.33% to 59.00% due to the hydrolysis ability of transglucosidase. Relative crystallinity of the retrograded starches decreased from 24.33% to 14.50%. Furthermore, the Avrami parameters demonstrated that transglucosidase treatment significantly retarded the retrogradation rate of wheat starch due to the decrease of re-crystalline rate. The outcoming would supply a solid theory foundation for exploring the wheat staple foods with higher qualities.

Controllability on topological structures and properties of hyperbranched epoxy resins

Hyperbranched epoxy resin (HERs) have attracted increasing attention from scientists and engineers, due to their excellent functionalities in homogenously reinforcing and toughening diglycidyl ether of bisphenol-A (DGEBA) without phase separation. However, it remains a great challenge to control the topological structures of HERs and to discover the effect of microstructure on the properties of epoxy resins. Here, we report the synthesis of NP skeleton epoxy hyperbranched polymer (NMHEP-n) with a controllable degree of branching (DB) and topological structures by a thiol-ene click reaction. The DB of NMHEP-n can be tuned readily with a ratio of designed branched and linear monomers from 0 to 1.0, which can determine the topological structure from linear rod-like chains to ellipsoidal, further to spherical molecular chains. With the increase of DB from 0 to 1.0, a root-mean-square z-average radius of gyration (Rg), hydrodynamic radius (Rh) and shape factor (ρ = Rg/Rh) decrease, being an agreement with the variation from linear to spherical shape. Performance of NMHEP-n/DGEBA composites, including cold resistance, tensile, flexural, and impact strengths, are significantly improved with an increase in DB and content, and the maximum value appears at 12 wt% NMHEP-0.5 in composites. The simultaneous improvement on various properties is attributed to a homogeneous reinforcing and toughening mechanism, which can be rationalized and substantiated by DMA, AFM, SEM, and Raman techniques. These results render an applicable approach to prepare high-performance thermosets and composites.

Tailoring Hyperbranched Poly(β-amino ester) as a Robust and Universal Platform for Cytosolic Protein Delivery.

Cytosolic protein delivery is a prerequisite for protein-based biotechnologies and therapeutics on intracellular targets. Polymers that can complex with proteins to form nano-assemblies represent one of the most important categories of materials, because of the ease of nano-fabrication, high protein loading efficiency, no need for purification, and maintenance of protein bioactivity. Stable protein encapsulation and efficient intracellular liberation are two critical yet opposite processes toward cytosolic delivery, and polymers that can resolve these two conflicting challenges are still lacking. Herein, hyperbranched poly(β-amino ester) (HPAE) with backbone-embedded phenylboronic acid (PBA) is developed to synchronize these two processes, wherein PBA enhanced protein encapsulation via nitrogen-boronate (N-B) coordination while triggered polymer degradation and protein release upon oxidation by H2 O2 in cancer cells. Upon optimization of the branching degree, charge density, and PBA distribution, the best-performing A2-B3-C2-S2 -P2 is identified, which mediates robust delivery of various native proteins/peptides with distinct molecular weights (1.6-430kDa) and isoelectric points (4.1-10.3) into cancer cells, including enzymes, toxins, antibodies, and CRISPR-Cas9 ribonucleoproteins (RNPs). Moreover, A2-B3-C2-S2 -P2 mediates effective cytosolic delivery of saporin both in vitro and in vivo to provoke remarkable anti-tumor efficacy. Such a potent and universal platform holds transformative potentials for protein pharmaceuticals.

Upcycling of blending waste plastics as flexible growing substrate with superabsorbing property

Converting blending waste plastics into lightweight growing substrate is an attractive approach for efficiently recycling low value-added waste plastics. In the current research, a universal and mild strategy for recycling blending waste plastics to fabricate blending plastic-g-growing substrate (BP-GS) with superabsorbing and flexible properties was developed. The incompatibility between blending waste plastics was successfully overcome, and the effects of several parameters on the synthesis and water absorption of BP-GS were established. Furthermore, the prepared BP-GS possessed high water-absorbing capacity (1188%), excellent porous structure and flexible properties. Mechanisms study demonstrated that the blending plastics formed uniform structure via crosslinking of macromolecular free radicals, and additives such as superabsorbent polymer (SAP) and polyolefin elastomer (POE) were grafted into the blending waste plastics by forming stable covalent bonds, generating hydrophilic and flexible BP-GS. Furthermore, the regulation of melt flow rate (MFR) was ascribed to the effect of POE on crystallinity and branching degree of the plastics. In addition, pot and slope experiments showed BP-GS could coordinate with soil to support plants growth for drought and landslide prevention. Meanwhile, sequencing analysis indicated a micro-ecosystem could be formed in the prepared BP-GS to support plants growth. Therefore, the synthesized superabsorbent has potential application in vertical greening and slope restoration. This high value-added and universal recycling method will promote eco-friendly, upcycling and circular development of blending waste plastics recovery.

Pore Scale Numerical Modelling of Geological Carbon Storage Through Mineral Trapping Using True Pore Geometries

Mineral trapping (MT)is the most secure method of sequestering carbon for geologically significant periods of time. The processes behind MT fundamentally occur at the pore scale, therefore understanding which factors control MT at this scale is crucial. We present a finite elements advection–diffusion–reaction numerical model which uses true pore geometry model domains generated from upmuCT imaging. Using this model, we investigate the impact of pore geometry features such as branching, tortuosity and throat radii on the distribution and occurrence of carbonate precipitation in different pore networks over 2000 year simulated periods. We find evidence that a greater tortuosity, greater degree of branching of a pore network and narrower pore throats are detrimental to MT and contribute to the risk of clogging and reduction of connected porosity. We suggest that a tortuosity of less than 2 is critical in promoting greater precipitation per unit volume and should be considered alongside porosity and permeability when assessing reservoirs for geological carbon storage (GCS). We also show that the dominant influence on precipitated mass is the Damköhler number, or reaction rate, rather than the availability of reactive minerals, suggesting that this should be the focus when engineering effective subsurface carbon storage reservoirs for long term security.Article HighlightsThe rate of reaction has a stronger influence on mineral precipitation than the amount of available reactant.In a fully connected pore network preferential flow pathways still form which results in uneven precipitate distribution.A pore network tortuosity of <2 is recommended to facilitate greater carbon mineralisation.

Effect of reaction conditions on the hydrogenolysis of polypropylene and polyethylene into gas and liquid alkanes

Hydrogenolysis of polypropylene and polyethylene provides a pathway to smaller hydrocarbons. We describe the impact of the polyolefin structure, reaction conditions, and presence of chlorine on the product distribution and branching degree.

4D Flat Panel Conebeam CTA for Analysis of the Angioarchitecture of Cerebral AVMs with a Novel Software Prototype.

Time-resolved 3DRA (4D-DSA) and flat panel conebeam CTA are new methods for visualizing the microangioarchitecture of cerebral AVMs. We applied a 4D software prototype to a series of cases of AVMs to assess the utility of this method in relation to treatment planning. In 33 patients with AVMs, 4D volumes and flat panel conebeam CTA images were recalculated from existing 3D rotational angiography data. The multiplanar reconstructions were used to determine intranidal arteriovenous branching patterns, categorize them according to common classifications of AVM angioarchitecture, and compare the results with those from 2D-DSA. 4D flat panel conebeam CTA showed angioarchitectural features equal to or better than those of 2D-DSA in 30 of 33 cases. In particular, the reconstructions helped in understanding the intranidal microvasculature. Fistulous direct arteriovenous connections with a low degree of arterial branching (n = 22) could be distinguished from plexiform arterial networks before the transition to draining veins (n = 11). We identified AVMs with a single draining vein (n = 20) or multiple draining veins (n = 10). Arteriovenous shunts in the lateral wall of the draining veins (n = 22) could be distinguished from cases with increased venous branching and shunts between corresponding intranidal arteries and veins (n = 11). Limitations were the time-consuming postprocessing and the difficulties in correctly tracing intranidal vessels in larger and complex AVMs. 4D flat panel conebeam CTA reconstructions allow detailed analysis of the nidal angioarchitecture of AVMs. However, further improvements in temporal resolution and automated reconstruction techniques are needed to use the method generally in clinical practice.

Native and fermented waxy cassava starch as a novel gluten-free and clean label ingredient for baking and expanded product development.

Amylose-free and wild-type cassava starches were fermented for up to 30 days and oven- or sun-dried. The specific volume (ν) after baking was measured in native and fermented starches. The average ν (across treatments) for waxy starch was 3.5 times higher than that in wild-type starches (17.6 vs. 4.8 cm3 g-1). The best wild-type starch (obtained after fermentation and sun-drying) had considerably poorer breadmaking potential than native waxy cassava (8.4 vs. 16.4 cm3 g-1, respectively). The best results were generally obtained through the synergistic combination of fermentation (for about 10-14 days) and sun-drying. Fermentation reduced viscosities and the weight average molar mass led to denser macromolecules and increased branching degree, which are linked to a high loaf volume. The absence of amylose, however, was shown to be a main determinant as well. Native waxy starch (neutral in taste, gluten-free, and considerably less expensive than the current alternatives to cassava) could become a new ingredient for the formulation of clean label-baked or fried expanded products.

Revealing Morphological Variability in Some Confectionery Pumpkin Genotypes

Bu çalışma, S4 kademesinde ümitvar olarak belirlenmiş 105 adet çerezlik kabak hattında (Cucurbita pepo L.), bazı morfolojik özelliklerin incelenmesi ve genotipler arası yakınlıklar belirlenmeye çalışılmıştır. Çalışmada bitki, meyve ve tohum özelliklerine ait bazı gözlem ve ölçümler yapılmıştır. Genotiplerin bitki görünümü %81.9 dik, %15.2 sarılıcı, %0.9 yarı sarılıcı bulurken kol atma derecesi %32.3 zayıf, %47.7’si orta %22.8 fazla, genotiplerde %84.7 kol atma var %15.2 kol atma yok olarak saptanmıştır. Genotiplerin %49.5’i yeşil gövdeli, %37.14’ü açık yeşil, %13,3’ü ise koyu yeşil olarak bulunmuştur. Genotiplerde yaprak, %64.7’si yeşil, %30.4 koyu yeşil, %4.7 açık yeşil renkte; %1.9’u az, %48.5’i orta, %2.8’i fazla, %4.7’si çok fazla dilimli, %41.9’u dilimsiz, olarak tanımlanmıştır. Meyve benek renginde, % 31.4’ü yeşil, %7.6’sı turuncu, %0.9’u sarı, %60’ı krem; benek yoğunluğunda; %73,3’ü az, %24.7’si yoğun, %1.9’u fazla; meyve renginde, %19.0’u krem, %4.7’si sarı, %0.9’u yeşil, %1.9’u yeşil-sarı, %4.7’si koyu-sarı, %28.6’sı açık sarı, %41.9’u turuncu olarak bulunmuştur. Tohumluk meyve boyu; %21.9’u kısa, %38.0’i orta, %40’ı uzun; meyve çapı genotiplerde %62.8’i uzun, %35.23’ü orta, %3.8’i dar olarak bulunmuştur. Genotiplerde meyve iriliği; %14.2’si iri, %36.1’i orta, %50.4’ü küçük, %0.9 küçük-orta olarak bulunmuştur. Elde edilen verilerle genotipler arasındaki genetik çeşitliliğin belirlenmesi amacıyla, temel bileşenler analizi (PCA) ile cluster analizi yapılmış ve genotiplerin 6 gruba ayrıldığı görülmüştür.

Effect of solvent on the microstructure of polyvinyl alcohol

AbstractThe method for producing polyvinyl alcohol (PVA) by the solution polymerization of vinyl acetate first and then alcoholysis strategy is industrial. Where solvent plays a vital role in control over stereoregularity, molecular weight and its distribution, crystallinity and so on. In this report, when methyl acetate was used as a solvent in the polymerization of vinyl acetate instead of methanol, prepared PVA was characterized by Fourier‐transform infrared spectroscopy (FT‐IR), nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results showed that PVA obtained in methyl acetate has a higher content of syndiotactic structure, crystallinity melting temperature and enhanced thermal stability compared with PVA obtained in methanol due to the formation of Π ‐ Π complex between methyl acetate and vinyl acetate and the enhanced steric hindrance effect during polymerization. Additionally, methyl acetate has a smaller chain transfer constant (1.31 × 10−4), which benefits to decrease the branching degree and molecular weight distribution index of PVA. This research provides more ideas for the choice of solvents in the industrial production of polyvinyl alcohol.

Structure, retrogradation and digestibility of waxy corn starch modified by a GtfC enzyme from Geobacillus sp. 12AMOR1

To lower the retrogradation and digestibility of waxy corn starch for different food applications, a novel thermostable GtfC type 4,6-α-glucanotransferase without N- and C- terminals (GsGtfC) from Geobacillus sp. 12AMOR1 was used. Waxy corn starch of 50 g/L was incubated with GsGtfC of 40–100 U/g substrate at 65 °C and pH 5.5 for 1 h. Its molecular weight, iodine affinity, XRD crystallinity, and FTIR ratio of heights of bands at 1047 and 1022 cm−1 decreased, but ratio of DP<6 to DP≥25 branches and degree of branching increased. GsGtfC cleaved α-1,4-glycosidic bonds and induced α-1,6-branching points to produce reuteran-likes polymers, which is different from Exiguobacterium sibiricum GtfC enzyme cleaving α-1,4-glycosidic bonds and synthesizing consecutive α-1,6-glycosidic bonds to produce isomalto/malto-oligosaccharides. GsGtfC modified waxy corn starch had significantly lower DSC retrogradation enthalpies during the storage at 4 °C for 3–14 days and significantly lower released glucose during the incubation with mammalian mucosal α-glucosidase at 37 °C for 10–360 min. GsGtfC at 100 U/g substrate increased slowly digestible portion from 11.07% to 24.11%.

Stress-strain behavior and corresponding crystalline structures of four types of polyethylene under a wide range of strain rates

Stress-strain behavior of four types of polyethylene (PE), i.e. low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), medium-density polyethylene (MDPE) and high-density polyethylene (HDPE), under a wide strain rate ranging from 0.001 to 1000 s−1, and the crystalline structures of corresponding fractured PEs were investigated. Results demonstrated that when the strain rate was less than 1 s−1, PE exhibited ductile fracture with a rougher section. While at strain rates larger than 1 s−1, the damage was manifested as brittle fracture with a smooth fracture surface. For all PE specimens, the yield strength increased with strain rate, but the increasing dependency of yield stress on strain rate was diverse in various strain rate ranges. Under the same strain rate, due to the largest molecular weight and lowest branching degree, HDPE showed the highest values in yield strength, crystallinity, crystal orientation degree, and crystallite size. At the appropriate stain rate, i.e. 10 s−1, HDPE with less branched structure is more likely to obtain higher crystallinity and molecular chain orientation degree.