Mild Degradation Research Articles

Highly efficient and mild electrochemical degradation of bentazon by nano-diamond doped PbO2 anode with reduced Ti nanotube as the interlayer

Anodic oxidation based on PbO2 anode has been demonstrated as the feasible approach for the decontamination of organic pollutants; however, the performance of this process is hindered by its ordinary electrochemical activity and relatively low stability. In this study, we fabricated an efficient Ti/TiO2-RNTs/Sb-SnO2/PbO2-ND electrode with electrochemically reduced TiO2 nanotubes as the interlayer and nano-diamond as the dopant. As compared with other electrodes, the constructed Ti/TiO2-RNTs/Sb-SnO2/PbO2-ND exhibited higher oxygen evolution overpotential, larger active area and less charge transfer resistance. Thus, the average current efficiency of 30% could be attained at 120 min with TiO2-NTs/Sb-SnO2/PbO2, which was 1.5 times higher in comparison with the typical Ti/Sb-SnO2/PbO2 electrode. It was found that the removal efficiency of COD could be increased from 49% to 69% after 120 min treatment in the presence of 10 mM Cl−1 in the electrolyte. After 6 h of electrolysis, 74% of TOC was removed and 31% and 22% of initial N was transformed into NH4+ and NO3− ions, respectively. And oxalic acid, glyoxylic acid, malonic acid and acetic acid were identified quantitatively as the intermediate products. Finally, it was estimated that the accelerated service life of Ti/TiO2-RNTs/Sb-SnO2/PbO2-ND electrode was approximately three times of Ti/Sb-SnO2/PbO2 electrode. Generally, this study is of great interest for the engineering community to design an efficient electrode material for the wastewater treatment.

A Cell-Based High-Throughput Screening Identified Two Compounds that Enhance PINK1-Parkin Signaling.

SummaryEarly-onset Parkinson's disease-associated PINK1-Parkin signaling maintains mitochondrial health. Therapeutic approaches for enhancing PINK1-Parkin signaling present a potential strategy for treating various diseases caused by mitochondrial dysfunction. We report two chemical enhancers of PINK1-Parkin signaling, identified using a robust cell-based high-throughput screening system. These small molecules, T0466 and T0467, activate Parkin mitochondrial translocation in dopaminergic neurons and myoblasts at low doses that do not induce mitochondrial accumulation of PINK1. Moreover, both compounds reduce unfolded mitochondrial protein levels, presumably through enhanced PINK1-Parkin signaling. These molecules also mitigate the locomotion defect, reduced ATP production, and disturbed mitochondrial Ca2+ response in the muscles along with the mitochondrial aggregation in dopaminergic neurons through reduced PINK1 activity in Drosophila. Our results suggested that T0466 and T0467 may hold promise as therapeutic reagents in Parkinson's disease and related disorders.

CXCL16 expression during post-traumatic osteoarthritis development: implications for mesenchymal stem cell recruitment

Purpose: Post-traumatic osteoarthritis (PTOA) develops following major joint trauma. Recently, we demonstrated that mesenchymal stem/multipotent stromal cells (MSCs) are recruited to the injured joint after ACL rupture (ACLR) in rats. While it is known that MSCs are recruited by chemokines, the temporal, injury-induced, intraarticular expression of chemokines and their specific roles in MSC recruitment remain largely undescribed. The purpose of this study was to characterize the in vivo expression of the understudied chemokine CXCL16, which can recruit MSCs via CXCR6, following ACLR. We also sought to assess whether primary fibroblast-like synoviocytes (FLS) from injured joint synovium are “reprogrammed” to exhibit differential CXCL16 expression compared to cells from a healthy joint. Finally, we assessed CXCL16- and FLS-mediated recruitment of MSCs in an in vitro chemotaxis model. Methods: With IACUC approval, ACLR was induced in adult C57BL/6 mice via tibial compression. 3- and 14-days post-injury, the synovium, menisci, and femoral and tibial epiphyses were analyzed with rtPCR for CXCL16 and ADAM10, the protease that cleaves CXCL16 from the cell membrane, (n=8 mice per time point). Further mice were injured and FLS were isolated to establish cultures (n=3 each) from injured and contralateral limbs 7-days post-injury. Cultured FLS were induced with cytokines and analyzed with rtPCR for CXCL16 expression. CXCL16 (10 and 50 ng/mL) was assessed for its role in recruitment of C3H10T1/2 cells, an MSC-like cell line, in an in vitro 3D chemotaxis system (Incucyte). Chemotaxis was quantified by automated calculation of cell-occupied area on the bottom membrane. Primary FLS were isolated from uninjured mouse synovium, induced with 10 ng/mL TNFα, co-cultured with C3H10T1/2 in the chemotaxis system, and analyzed for the ability to recruit C3H10T1/2 MSCs. Results: Histology grading shows mild PTOA and moderate synovitis in mice following ACLR, as evidenced by mild cartilage degradation, early osteophyte formation, and pronounced synoviocyte hyperplasia at 3 and 14d (Fig 1). Compared to contralateral knees, the synovium of injured limbs exhibited no upregulation of IL-17, but significant increases in TNFα (P=0.026) and IL-1β (P=0.017) at 3d and in TNFα at 14d (P=0.006). Both CXCL16 and ADAM10 are significantly upregulated by the synovium in vivo 3d after injury and remain elevated at 14d (Fig 2). The menisci of injured limbs upregulated CXCL16 at both 3d (P<0.001) and 14d (P<0.001), but there was no change in ADAM10 expression in meniscus. Results from both epiphyseal tissues showed no upregulation in chemokine expression between injured and contralateral limbs (Fig 2). Primary FLS from injured joints upregulated CXCL16 when treated with TNFα (P=0.025) and IL-1β (P=0.006), and interestingly, FLS from contralateral joints showed similar upregulation in response to TNFα (P=0.002) and IL-1β (P=0.006) (Fig 3). There was no difference in CXCL16 expression between injured and injured FLS. 3D chemotaxis assays demonstrate that 50 ng/mL CXCL16, but not 10 ng/ml, induces C3H10T1/2 chemotaxis. Further, TNFα-stimulated FLS induce C3H10T1/2 chemotaxis to a greater extent than unstimulated FLS or TNFα-containing media alone, demonstrating the ability of cytokine activated FLS to recruit MSC-like cells (Fig 4).View Large Image Figure ViewerDownload Hi-res image Download (PPT)View Large Image Figure ViewerDownload Hi-res image Download (PPT)View Large Image Figure ViewerDownload Hi-res image Download (PPT) Conclusions: Our data demonstrate that noninvasive ACLR causes mild PTOA and moderate synovitis up to 14d post-ACLR, with concurrently increased expression of cytokines. In vivo injury-induced upregulation of CXCL16 and ADAM10 by the synovium provide evidence for CXCL16’s possible role in recruiting MSCs, which highly express CXCR6. CXCL16 was upregulated by the meniscus of the injured joint at 3d with persistent upregulation at 14d. Our in vitro data demonstrate that the FLS is a contributor to CXCL16 expression, and this is mediated by both IL-1β and TNFα. Similar CXCL16 expression between FLS isolated from contralateral and injured limbs suggests that although profound inflammation is observed in vivo following ACLR, this inflammatory environment did not “reprogram” the FLS to exhibit greater CXCL16 expression in response to cytokines. Further studies will explore later time points to determine if such “stromal memory” is demonstrated by FLS in later stages of PTOA. Finally, we have established an in vitro model to study MSC recruitment and FLS-MSC interactions, as we demonstrate both CXCL16 and cytokine-induced FLS can recruit MSC. Ongoing work is employing inhibitors to assess the role of CXCL16 in FLS-mediated MSC recruitment.

Characterization and Localization of Dynamic Cell Wall Structure and Inorganic Species Variability in Harvested and Stored Corn Stover Fractions as Functions of Biological Degradation

Traditional approaches for corn stover utilization create an inhomogeneous, whole plant mixture that does not achieve performance and cost targets for biofuel production. The improvement of conversion performance will require one to gain a fundamental understanding of the inherent cellular structure and ash content in the process. This study investigated cellular structure and inorganic species contents with scanning electron microscopy (SEM), advanced energy dispersive X-ray spectroscopy (EDS), and wet analytical chemistry methods. These techniques provided a complementary means to understand variability within the dynamic cell walls and the distributions of inorganic species at the anatomical and tissue scales for various corn stover fractions. Material properties were investigated for bales from in-field storage scenarios ranging from mild to severe biological degradation. Results show that stem, cob, and leaf tissues all maintained cell wall and surface structure integrity after mild biological degradation. However, severe degradation (with spontaneous heating) caused remarkable structural distortion and cell wall shrinkage for all tissue types. Inorganic species quantitation data shows that three fractions of severe degradation have slightly reduced total ash, 4.91% vs 3.92% for cobs, 7.28% vs 5.98% for stems, and 14.21% vs 13.07% for leaves. Silica contents also decreased (2.67% vs 1.83% for cobs, 3.60% vs 2.89% for stems, and 9.72% vs 8.48% for leaves), likely due to the loss of extrinsic inorganic species. SEM-EDS inorganic species mapping of stems demonstrated that severe biological degradation caused the translocation of the dominant silicon elements from pith to rind tissue as well as a reduction of potassium in the stem. These findings offer detailed knowledge of feedstock variability at the anatomical tissue level that can be used to inform the development of advanced processing strategies. Innovative storage and selective fractionation processes have the potential to manage low-quality fractions/tissues and remove unfavorable inorganic species for efficient conversion of corn stover as well as other lignocellulosic biomass.

Interfacial modification and tribological properties of carbon fiber grafted by TiO2 nanorods reinforced novel depolymerized thermosetting composites

In this study, homogeneous and dense TiO2 nanorods (TiO2 NRs) were grafted onto carbon fiber (CF) simply by hydrothermal method to enhance the interfacial bonding between CF and poly(hexahydrotriazine)s (PHTs) matrix and improve the tribological properties of CF reinforced polymer composites (CFRPs). The oriented TiO2 NRs impacted the mechanical properties by supplying mechanical interlock. As growth of TiO2 NRs increased, the tensile strength and modulus enhanced by about 31.8% and 15.1% when compared to neat CF. Most importantly, the wear rate of PHT/TiO2@CFC reduced by 55.1% when compared to PHT/CFC, leading to stable friction profile. The wet friction test in seawater and sunflower oil also demonstrated satisfied wear resistance of PHT/TiO2@CFC, where wear rate decreased by 46.6%. On the other hand, mild degradation solution might effectively recycle CF from PHT/TiO2@CFC composite without damage to properties. In sum, the proposed alternative method for multiscale modification of CF surfaces looks promising for manufacturing of advanced recyclable CFRPs for tribological applications.

Autoproducts in and near acoustic shadow zones created by barriers.

The autoproducts are nonlinear mathematical constructs developed from acoustic fields with non-zero bandwidth. When averaged through the field's bandwidth, the autoproducts may mimic a genuine acoustic field at frequencies that are lower or higher than the original field's bandwidth. The resulting opportunity to extend signal processing to user-selectable below- or above-band frequencies is intriguing for many signal processing algorithms. Based on prior work, the limitations of the autoproducts' mimicry of out-of-band fields are understood when the in-band acoustic field is well-represented by ray acoustics. Thus, the focus in this study is on autoproducts in acoustic shadow zones behind barriers containing only diffracted acoustic fields where a sum of ray-path contributions is not an adequate field description. Diffraction is expected to be a detriment to autoproduct techniques due to its sensitivity to frequency. Two ideal shadow-zone environments with exact analytic Helmholtz-equation solutions are considered: Sommerfeld's half-plane problem, also known as knife-edge diffraction, and Mie scattering from a sphere with ka = 40, where k is the wavenumber and a is the sphere's radius. With the exception of the shadow regions, autoproducts experience only mild degradation in field-mimicry performance when compared to what the ray-based theory would predict.

Coordinated static control of asynchronous sequential machines

This paper considers static corrective control of asynchronous sequential machines (ASMs). While static corrective controllers are more efficient than dynamics ones as their implementation needs no memory elements, they have restrictive existence conditions in association with transient states. To alleviate this drawback, we propose a framework of coordinated static control for ASMs. A number of single static controllers are designed to achieve local objectives and the coordinator selects the active controller among them based on the external input and state feedback so that the overall behavior of the closed-loop system matches that of a reference model. Compared with previous static controllers, the existence condition is much improved with mild degradation of design complexity.

Three-year follow-up of prospective trial of focused ultrasound thalamotomy for essential tremor.

To test the hypothesis that transcranial magnetic resonance-guided focused ultrasound (tcMRgFUS) thalamotomy is effective, durable, and safe for patients with medication-refractory essential tremor (ET), we assessed clinical outcomes at 3-year follow-up of a controlled multicenter prospective trial. Outcomes were based on the Clinical Rating Scale for Tremor, including hand combined tremor-motor (scale of 0-32), functional disability (scale of 0-32), and postural tremor (scale of 0-4) scores, and total scores from the Quality of Life in Essential Tremor Questionnaire (scale of 0-100). Scores at 36 months were compared with baseline and at 6 months after treatment to assess for efficacy and durability. Adverse events were also reported. Measured scores remained improved from baseline to 36 months (all p < 0.0001). Range of improvement from baseline was 38%-50% in hand tremor, 43%-56% in disability, 50%-75% in postural tremor, and 27%-42% in quality of life. When compared to scores at 6 months, median scores increased for hand tremor (95% confidence interval [CI] 0-2, p = 0.0098) and disability (95% CI 1-4, p = 0.0001). During the third follow-up year, all previously noted adverse events remained mild or moderate, none worsened, 2 resolved, and no new adverse events occurred. Results at 3 years after unilateral tcMRgFUS thalamotomy for ET show continued benefit, and no progressive or delayed complications. Patients may experience mild degradation in some treatment metrics by 3 years, though improvement from baseline remains significant. NCT01827904. This study provides Class IV evidence that for patients with severe ET, unilateral tcMRgFUS thalamotomy provides durable benefit after 3 years.

Green Tea Polyphenol Induced Mg2+-rich Multilayer Conversion Coating: Toward Enhanced Corrosion Resistance and Promoted in Situ Endothelialization of AZ31 for Potential Cardiovascular Applications.

As a promising biodegradable metallic material, magnesium (Mg) and its alloys have attracted special attention in the recent decade. However, challenges still remain due to its high corrosion rate and insufficient biocompatibility after implantation. In this work, we prepare a simple and versatile green tea phenol-metal induced multilayer conversion coating (Mg2+ incorporated epigallocatechin gallate (EGCG) coating) on magnesium alloys' (AZ31) substrate by layer-by-layer (LBL) method. The surface morphology results revealed that, with the incorporation of Mg2+, the as-formed EGCG/Mg coating was rich in phenol-Mg complex and presented more homogeneous and dense morphology, with far less cracks than the pure EGCG coating. The in vitro degradation rate and corrosion resistance were studied by electrochemical corrosion tests and monitoring of the changed pH value and hydrogen evolution, respectively, which revealed that the corrosion rate was effectively decreased compared to that of bare AZ31 after it was protected by EGCG/Mg coating. In vitro and ex vivo thrombogenicity test demonstrated the EGCG/Mg coatings presented an impressive improvement in decreasing the adhesion and activation of platelets and erythrocytes, in activated partial thromboplastin time (APTT), and in antithrombogenicity compared to those of bare AZ31. Owing to the mild degradation rate, in combination with the biological function of EGCG, enhanced endothelial cells' (ECs') adhesion and proliferation, suppressed smooth muscle cells' (SMCs') adhesion/proliferation, and inhibited cytokine release were observed on EGCG/Mg coated AZ31 alloy. Besides, the in vivo subcutaneous embedding experiment suggested that the EGCG/Mg coating performed more mild tissue response due to the improved corrosion resistance to the surrounding microenvironment. Moreover, for in vivo abdominal aorta assay, the EGCG/Mg coated AZ31 wire presented better corrosion resistance and enhanced re-endothelialization compared to bare AZ31 wire. These results suggested the potential of using green tea polyphenol induced Mg2+-rich multilayer conversion coating for enhanced corrosion protection and desired biocompatibility of biodegradable cardiovascular implants.

Influence of structure water on crystal structure of hydrated molybdenum oxide and its interesting photothermal catalytic performances under indoor ambient conditions

From the viewpoint of engineering application, it is highly desirable to develop a low-cost, fossil energy–saving degradation technology. In this work, hydrated molybdenum oxide (MoO3·0.55H2O) is prepared by a simple chemical method. It is interesting that under indoor natural ambient conditions, 79% of methylene blue is degraded by hydrated molybdenum oxide after 150 min, but under the same conditions, anhydrous molybdenum oxide does not have any degradation activity. It is found that the outstanding ambient activity of hydrated molybdenum oxide is mainly attributed to the photothermal synergistic effect caused by structure water. On one hand, the coordination of structure water with molybdenum brings about the Jahn–Teller distortion of MoO6 octahedron, giving rise to Lewis acid sites that promote the adsorption and activation of oxygen. O2–temperature-programmed desorption and H2–temperature-programmed reduction profiles show that compared with MoO3, MoO3·0.55H2O has a higher oxygen adsorption ability and a higher oxidation ability. Jahn–Teller effect is mainly responsible for the thermocatalytic activity. On the other hand, the ligand-to-metal charge transfer (LMCT) transfer from structure water to molybdenum obviously increases the light absorption, thus LMCT is mainly responsible for the photocatalytic activity The most important is that compared with conventional photocatalysis, no artificial light source equipment is required; compared with thermocatalysis, no extra heating equipment is needed. Thus, this mild degradation process is low-cost, energy-saving and space-saving, which is very promising for indoor or limited space cleaning.

Mild oxidative degradation of spent auricularia auricular substrate and molecular composition of carboxylic acids in the resulting soluble portion

Spent auricularia auricular substrate (SAAS) was oxidatively degraded with aqueous hydrogen peroxide (AHPO)/acetic anhydride (AAH) to produce carboxylic acids (CAs) under mild conditions. The results show that up to 53.6% of the organic matter in SAAS was converted to the soluble species (SSs). In total 122 CAs were detected in the SSs by the analysis with a gas chromatograph/mass spectrometer, which can be classified into 29 group components, mainly being aliphatic acids and along with small amount of aromatic acids. Among the aliphatic acids, normal alkanedioic acids are the most abundant. The detected aromatic acids include benzoic acids, phthalic acids, trimellitic acids, pyromellitic acids, and their derivatives. The synergistic oxidation and the released OH, CH 3 COO , and HOO induced by AHPO/AAH play crucial roles in oxidatively degrading SAAS. • SAAS can be degraded to produce CAs, which consists of aliphatic acids and aromatic acids. • Aliphatic acids represent the predominant species, and NADAs are the most abundant. • AHPO/AAH ratio and temperature have impact on the composition and yield of CAs. • OH, CH 3 COO , and HOO play crucial roles in the SAAS oxidative degradation.

Mg-Incorporated Egcg Coating on AZ31 with Biocompatible Corrosion Protection for Vascular Implants

As a promising biodegradable metallic material, magnesium (Mg) and its alloys have attracted special attention in recent decade. However, challenges still remain due to its high corrosion rate and insufficient biocompatibility after implantation. In this work, we put forward a coating concept on AZ31 surface via mimicking a 'tea stain' formation process using a layer-by-layer approach. Epigallocatechin gallate (EGCG) incorporating Mg2+ ions is used to form a chemical conversion coating on AZ31 magnesium alloy with enhanced corrosion protection and favorable biocompatibility for cardiovascular implants. The SEM and AFM morphology results revealed that with the incorporation of Mg2+, the as-formed EGCG/Mg coating was more homogeneous and dense, with far more less cracks than the pure EGCG coating. The in vitro degradation rate and corrosion resistance were studied by electrochemical corrosion tests and monitoring of the changed pH value and hydrogen evolution, respectively, which revealed that the corrosion rate of EGCG/Mg riched coating was effectively decreased than that of pure EGCG coating and bare AZ31 substrate. Owing to the mild degradation rate, in combination of the biological function of EGCG, enhanced endothelial cells (ECs) adhesion and proliferation, suppressed smooth muscle cells (SMCs) adhesion/proliferation and inhibited cytokine release were observed on EGCG/Mg coated AZ31 alloy. Besides, the in vivo subcutaneous embedding experiment strongly indicated that the EGCG/Mg coating performed more mild tissue response due to the improved corrosion resistance to surrounding microenvironment. Ex-vivo thrombogenicity test demonstrated the EGCG/Mg coatings presented an impressive improvement in anti-thrombogenicity compared to bare AZ31. These results convincingly demonstrated the potential of using Mg-incorporated EGCG coating as a biocompatible barrier on the biodegradable magnesium alloy for vascular implants.

Glyco-Platelets with Controlled Morphologies via Crystallization-Driven Self-Assembly and Their Shape-Dependent Interplay with Macrophages.

Two-dimensional (2D) materials are of great significance to the materials community as a result of their high surface area and controllable surface properties. However, controlled preparation of biodegradable 2D structures with biological activity is difficult. In this work we demonstrate that by careful selection of building block structures and assembly conditions it is possible to use crystallization-driven self-assembly (CDSA) to assemble well-defined 2D nanostructures from poly(l-lactide) (PLLA)-based diblock glycopolymers. 1D glyco-cylinders and 2D diamond-shaped glyco-platelets are produced, where the underlying formation mechanism is revealed by dissipative particle dynamics simulations. Furthermore, we demonstrate that assembly of thepolymers under mild degradation provides a straightforward route to hollow-cored platelets, a morphology that has previously proven laborious to access. The well-defined sizes and shapes of the glyco-platelets allow us to investigate macrophage activation efficiency and demonstrate clear size and shape effects, pointing toward potential applications in immunology.

Pastures Degradation and the Relation with Pedo-Geomorphological Attributes in Watershed

ABSTRACT The objective of this study was to map the levels of degradation of pastures and its association with chemical properties of the soil and relief. We selected a sub-basin located in the municipality of Vicosa, Minas Gerais, and we mapped the degradations through Ikonos images that were submitted for classification. Soil samples were collected and analyzed chemically; the results were transformed in spatial data using cokriging, based on variables of the digital elevation model. We associated the maps (cokriging) with data from exposure of the hillside, levels of solar radiation and levels of the pastures’ degradation. The pastures were mainly classified in moderate (44%) and very strong (30%) degradation levels. The areas with mild degradation tend to increase when there is a higher sum of bases, cationic exchange capacity and organic matter. The portions facing North and the increase of solar radiation showed more advanced stages of degradation.

A Bayesian method for combining theoretical and simulated covariance matrices for large-scale structure surveys

Accurate and precise covariance matrices will be important in enabling planned cosmological surveys to detect new physics. Standard methods imply either the need for many N-body simulations in order to obtain an accurate estimate, or a precise theoretical model. We combine these approaches by constructing a likelihood function conditioned on simulated and theoretical covariances, consistently propagating noise from the finite number of simulations and uncertainty in the theoretical model itself using an informative Inverse-Wishart prior. Unlike standard methods, our approach allows the required number of simulations to be less than the number of summary statistics. We recover the linear ‘shrinkage’ covariance estimator in the context of a Bayesian data model, and test our marginal likelihood on simulated mock power spectrum estimates. We conduct a thorough investigation into the impact of prior confidence in different choices of covariance models on the quality of model fits and parameter variances. In a simplified setting, we find that the number of simulations required can be reduced if one is willing to accept a mild degradation in the quality of model fits, finding that even weakly informative priors can help to reduce the simulation requirements. We identify the correlation matrix of the summary statistics as a key quantity requiring careful modelling. Our approach can be easily generalized to any covariance model or set of summary statistics, and elucidates the role of hybrid estimators in cosmological inference.

Reductive Cleavage of Organic Peroxides by Iron Salts and Thiols.

Despite the low bond strength of the oxygen–oxygen bond, organic peroxides are often surprisingly resistant to cleavage by nucleophiles and reductants. As a result, achieving decomposition under mild conditions can be challenging. Herein, we explore the reactivity of a selection of peroxides toward thiolates, phenyl selenide, Fe(II) salts, and iron thiolates. Peroxides activated by conjugation, strain, or stereoelectronics are rapidly cleaved at room temperature by thiolate anions, phenylselenide, or Fe(II) salts. Under the same conditions, unhindered dialkyl peroxides are only marginally reactive; hindered peroxides, including triacetone triperoxide and diacetone diperoxide (DADP), are inert. In contrast, all but the most hindered of peroxides are rapidly (<1 min at concentrations down to ∼40 mM) cleaved by mixtures of thiols and iron salts. Our observations suggest the possible intermediacy of strongly reducing complexes that are readily regenerated in the presence of stoichiometric thiolate or hydride. In the case of DADP, an easily prepared explosive of significant societal concern, catalytic amounts of iron and thiol are capable of promoting rapid and complete disproportionation. The availability of inexpensive and readily available catalysts for the mild reductive degradation of all but the most hindered of peroxides could have significant applications for controlled remediation of explosives or unwanted radical initiators.

Thermal and physicochemical properties of sugar palm fibre treated with borax

Natural fibres are biodegradable, low-cost, and low-density materials found in many parts of the world in large quantities. The comparative properties and competitive advantages make it be a preferred material in many engineering applications. The major challenges associated with natural fibres are its low thermal stability, lack of interfacial adhesion, poor resistance to moisture and inferior mechanical properties when compared with synthetic fibres. The solution is to treat it with either alkali, silane, or other treatment methods. Specifically, alkaline treatment comes with an additional problem such as fibre degradation. Therefore, this work employed the use of borax as a treatment chemical rather than its usage as a fire retardant. This could give a treated natural fibre with mild degradation and acceptable properties. Therefore, in this research sugar palm fibre was treated with 5 w/w% borax, washed several times and dried in an oven. The treated and untreated fibres were characterized based on X-Ray Diffraction, thermal stability, and morphological analysis. The experimental results showed that the crystallinity index increased from 44.02 % to 49.56 %, while the thermal stability increased from 246.76 °C to 255.5 °C with borax treatment. The morphological investigation revealed that the surface of the treated fibre is rough with no silica deposit when compared with the untreated fibre. In conclusion, the investigation proved that treatment with the borax has a significant effect on the physicochemical properties of sugar palm fibre.

Surfactant effect on air/water flow in a multistage electrical submersible pump (ESP)

The surfactant effect on ESP boosting pressure under air–water flow is studied in this paper. A two-phase flow loop comprising a 7.62 cm diameter stainless steel liquid loop and 1.25 cm diameter gas loop is built up to conduct experimental measurements. A radial-type ESP with 14 stages assembled in series is installed on the testing bench. Pressure ports are drilled at inter-stage to measure the stage-by-stage pressure increment. The surfactant, isopropanol (IPA) is injected to change the interfacial properties of working fluids. Experiments are carried out with mapping and surging test schemes to evaluate pump behaviors at different operational conditions. ESP pressure increment under single-phase water flow agrees well with the catalog curves. For mapping tests without surfactant injection, ESP performance suffers from a severe degradation as gas flow rate increases. High gas entrainment rate causes oscillations of liquid flow rate and pump boosting pressure, featured by the instabilities of ESP operations. A sudden drop of ESP pressure increment, termed as pressure surging, occurs at the critical inlet gas volumetric fraction (GVF). For a larger rotational speed, the critical GVF is higher. With surfactant injection, ESP boosting pressure improves significantly. At different GVFs, only mild degradation is observed. Pressure surging phenomenon disappears. Further, liquid flow rate and pump boosting pressure are more stable at high GVFs compared to experimental data without surfactant injection.

Mild degradation of Powder River Basin sub-bituminous coal in environmentally benign supercritical CO2-ethanol system to produce valuable high-yield liquid tar

A novel and environmentally benign binary supercritical fluid system, comprised of supercritical CO2 and ethanol (SCCO2-ethanol), was employed to convert coal, a conventional energy resource, into high-value liquid tar which can be used as feedstock for the production of fuels/chemicals and carbon fibers. The SCCO2-ethanol system shows good performance for producing valuable liquid tar in high yield from Powder River Basin sub-bituminous coal. The results show that the highest yield of liquid tar reaches up to approximate 38 wt% (38 g/100 g raw coal) at 350 °C, and that SCCO2 can promote the liquid tar yield by 5.6 wt% compared to that using pure ethanol due to the synergistic effect between ethanol and SCCO2. The liquid tars are better candidates as clean fuels than the raw coal or even bituminous coal due to their higher heating values and almost free from ash. The liquid tars from degradation in SCCO2-ethanol (liquid tarSCCO2-ethanol) and in ethanol without SCCO2 (liquid tarethanol) at 350 °C were characterized with multiple analytical techniques. Fourier transform infrared analyses indicated that both liquid tars have similar distributions of functional groups. The proportion of volatile and small-molecular species in liquid tarSCCO2-ethanol is higher than liquid tarethanol according to thermogravimetric analysis. Further, gas chromatograph/mass spectrometry analyses show that phenols and aliphatic esters are the dominant volatile compounds in both liquid tars. The 1H and 13C nuclear magnetic resonance analyses reveal that both liquid tars have low aromaticity and liquid tarSCCO2-ethanol contains more aromatic carbons than liquid tarethanol, especially highly condensed aromatic carbons. Methylene and aliphatic and aromatic CH3 are the major aliphatic moieties in both liquid tars. The liquid tars can be separated into light oil and asphaltene fractions by extraction with n-heptane. In addition, the asphaltene fraction has potential to be used as the precursor for fabricating carbon nanofibers via electrospinning. Possible mechanisms for releasing volatile compounds and asphaltene from Powder River Basin sub-bituminous coal by SCCO2-ethanol degradation were also discussed.

O-Antigens of Escherichia coli Strains O81 and HS3-104 Are Structurally and Genetically Related, Except O-Antigen Glucosylation in E. coli HS3-104.

Glycerophosphate-containing O-specific polysaccharides (OPSs) were obtained by mild acidic degradation of lipopolysaccharides isolated from Escherichia coli type strain O81 and E. coli strain HS3-104 from horse feces. The structures of both OPSs and of the oligosaccharide derived from the strain O81 OPS by treatment with 48% HF were studied by monosaccharide analysis and one- and two-dimensional 1H- and 13C-NMR spectroscopy. Both OPSs had similar structures and differed only in the presence of a side-chain glucose residue in the strain HS3-104 OPS. The genes and the organization of the O-antigen biosynthesis gene cluster in both strains are almost identical with the exception of the gtr gene cluster responsible for glucosylations in the strain HS3-104, which is located elsewhere in the genome.