Synthesis of Reprocessable Lignin-based Non-isocyanate Poly(imine-hydroxyurethane)s Networks

In this study,an environmentally friendly and non-toxic route to synthesize lignin-based non-isocyanate poly(imine-hydroxyurethane)s networks was explored.Specifically,the NH₂-terminated polyhydroxyurethanes(NPHUs)prepolymer was first synthesized from bis(6-membered cyclic carbonate)(BCC)and diamine via the ring-opening reaction.Subsequently,the corresponding ligninbased non-isocyanate polyurethanes(NIPUs)with tunable properties were synthesized from NPHUs and levulinate lignin derivatives containing ketone groups via the Schiff base reaction.The structural,mechanical,and thermal properties of NIPUs with different stoichiometric feed ratios of BCC and levulinate lignin were characterized by Fourier transform infrared spectroscopy(FT-IR),nuclear magnetic resonance(NMR),differential scanning calorimetry(DSC),dynamic mechanical analysis(DMA),and thermogravimetric analysis(TGA).The results indicated that the tensile strength,Young's modulus,toughness,storage modulus,glass transition temperature,and thermal stability of lignin-based NIPUs gradually increased with increasing lignin content,and the highest Young's modulus of 41.1 MPa was obtained when lignin content reached 45.53%.With good reprocessing properties,this synthetic framework of ligninbased NIPUs also provides sustainable non-isocyanate-based substitutions to traditional polyurethane networks.     

木质素基非异氰酸酯聚氨酯的研究进展

聚氨酯（PU）是用途广泛的聚合物材料之一。目前,以生物质资源为原料,合成非异氰酸酯聚氨酯（NIPU）的技术受到越来越多的关注。木质素是自然界中储量丰富的天然可再生芳香族聚合物,功能化木质素可用于替代不可持续的石油基原料,开发高附加值的NIPU产品。本文综述了近年来以木质素为原料合成NIPU的方法和策略,介绍了利用木质素及其功能化衍生物合成木质素基NIPU的研究进展,并展望了木质素基NIPU在泡沫材料、木材黏合剂、弹性体、涂料等相关领域的应用潜力。     

基于配位作用的木质素基阻燃/自修复聚氨酯弹性体的制备及性能研究

通过控制以三氮唑基团封端的星形结构木质素（L-TA）和聚氨酯预聚体（P-TA）的比例,在不同金属离子的配位作用下制备了木质素基自修复弹性体,并通过加入内含三氮唑基团的阻燃剂DT以提高弹性体的阻燃性能。当用DT代替10% L-TA时,在Fe³⁺配位作用下,70P-TA/20L-TA/10DT的拉伸强度相比于纯P-TA提高了88.4%。同时,70P-TA/20L-TA/10DT的极限氧指数值达29.5%,UL-94测试达V-0级。然而,L-TA和DT的加入增加了分子链段的空间位阻,降低了分子链迁移率,70P-TA/20L-TA/10DT的自修复效率由纯P-TA的91.1%下降至81.3%。此外,相比于其他金属离子,Zn²⁺—N较低的配位键强度使得70P-TA/20L-TA/10DT: Zn²⁺的玻璃化转变温度（T_g）随之降低,从而提高了聚合物链的流动性,使其具有较高的自修复效率（87.7%）。     

乙酸木质素基聚氨酯薄膜的合成与性能研究

以乙酸木质素(AAL)、聚乙二醇(PEG)和4,4’-二苯基甲烷二异氰酸酯(MDI)为原料合成了聚醚型聚氨酯薄膜,采用FTIR、TGA、DSC和拉伸试验对薄膜的结构和性能进行了研究。结果表明,PEG的链段长度是影响薄膜性能的主要因素。随着PEG链段长度的增加,聚氨酯材料的玻璃化转变温度降低,热分解温度升高;采用链段较长的聚乙二醇的薄膜,刚性小,引入PEG400的薄膜断裂伸长率最大可达292%。当木质素含量达到30%时,薄膜的拉伸强度和伸长率大幅度下降。     

Synthesis and Application of New Thickerners Part I: Preparation of Poly (Acrylic Acid)-Starch Graft Copolymer

Graft polymerization of maize starch with acrylic acid using potassium persulphate as free radical initiator was investigated under different conditions. Variables studied included initiator concentration, acrylic acid concentration, starch/water ratio and polymerization temperature. The carboxyl content of the grafted starch was determined and used for calculation of the grafted yield. It was found that the graft yield increases by increasing persulphate; no significant enhancement in grafting could be observed upon using higher persulphate concentrations. Grafting increases also by increasing acrylic acid concentration up to 150% (based on wt. of starch) and tends to decrease at higher concentrations. Starch/water ratio of 1:6 constitutes the optimal for maximum grafting. Raising the polymerization temperature from 25 to 43°C enhances the polymerization rate. The apparent activation energy of the copolymerization reaction amounts to 182.17 Joule/mole.     

Tin(II)-quercetin complex: Synthesis, spectral characterisation and antioxidant activity

The complex formation between quercetin (Q) and stannous chloride (SnCl₂·2H₂O) was studied using UV-visible, IR and ¹H NMR spectroscopic techniques. Spectroscopic data suggest that Q can chelate stannous cations through both 3-hydroxy-4-carbonyl and the 3′,4′-dihydroxyl (catechol) chelation sites. The antioxidant activity of the complex was evaluated using 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azinobis 3-ethylbenzothiazoline-6-sulphonic acid (ABTS) diammonium salt and ferric reducing antioxidant power (FRAP) methods. It was shown that radical scavenging activity and ferric reducing potential of free Q was decreased after chelation of stannous cation.     

山奈酚-铜配合物的合成、表征及其抗氧化活性的研究

以山奈酚和二水合氯化铜为原料,合成山奈酚-铜金属配合物,通过紫外光谱、红外光谱、核磁共振氢谱及差热-热重分析对其结构进行表征,并采用DPPH法测定了配合物清除自由基的能力。结果表明:相比山奈酚,配合物的紫外光谱和红外光谱的吸收峰均发生明显红移;核磁共振氢谱中3-OH信号消失,其他质子信号均向高场移动;差热-热重分析显示山奈酚和Cu²⁺的配位比为1,且配合物中含三分子的配位水;在6种设定的实验浓度内(1.0~3.5 mol/L),山奈酚和配合物清除DPPH·半抑制浓度(IC₅₀)分别为1.63×10^-4、1.51×10^-4 mol/L。Cu²⁺是通过与山奈酚3位羟基和4位羰基的氧原子结合生成配合物,山奈酚与铜形成配合物后,对DPPH自由基的清除率有提高。     

Analysis of warp-knitted fabric structure. Part II: theoretical study on initial modulus of warp-knitted fabrics (tricot,locknit, and satin)

In the first part of this series, a 3D straight line model was presented for the geometry of two-guide-bar warp-knitted fabrics. In this part, first, the variation of unit cell geometry under uniaxial tension in the range of elastic deformation is investigated. In the present study, the energy method and Castiglianos's theorem were used to derive the fabric's initial modulus. Energy terms which are considered in this study are extension, bending, and compression energies. Also, the friction phenomenon is taken into account by using frictional energy term. For this purpose, the loop of each bar is divided into eight elements. Free-body diagrams of elements are drawn to show the relative magnitude and direction of all forces acting upon an object in a given situation. After obtaining the force details, strain energy of each element is calculated. Finally, the initial modulus of warp-knitted fabrics is obtained. To verify the model, samples of tricot fabrics were produced and tested. Results showed that the generated model can predict precisely the initial modulus of aforementioned warp-knitted structures.     

雷林一号桉木材AS—AQ蒸煮及残余木素和溶出木素的特性

研究结果表明:蒸煮到145℃以前,木素磺化反应占主导地位,温度升高木素大量溶出。蒸煮后期,残余术素和溶出木素发生缩合反应,从而导致纸浆的KMnO_4值上升,白度下降。通过研究,论证了纸浆中残余木素含量高的原因。     

Novel Nanoporous Superabsorbent Hydrogel Based on Poly(acrylic acid) Grafted onto Salep: Synthesis and Swelling Behavior

Hydrogels of poly(acrylic acid) grafted onto salep with excellent water absorption and water retention abilities under neutral conditions were successfully synthesized for the first time and employed for different applications. The effect of reaction variables to achieve maximum swelling capacity was investigated. In our procedure, ammonium persulfate (APS) as a water‐soluble initiator and methylenebisacrylamide (MBA) as a suitable crosslinking agent were used and the best synthesis conditions described. The structure of the final product was confirmed by Fourier‐transform infrared (FTIR) spectroscopy, scanning electron microscopy SEM and TGA analysis and a mechanism for superabsorbent hydrogel formation was also suggested. The study of the surface morphology of hydrogels using SEM showed a highly nanoporous and cellular structure for the sample obtained under optimized condition. Furthermore, several factors which influence the water uptake of hydrogels, such as pH of water, sensitivity to salt solutions and solvent mixtures were examined.     

A Model of Seam Pucker and Its Applications. Part II: Experimental

Abstract

A simple model of a lockstitch seam (301) has been developed in part I, which is used to derive a measure of the severity of puckering in the seam.

This article compares the numerical assessment of pucker, derived from the model in part I, with fabric mechanics experiments and visual assessments of the phenomenon. It is shown that there is good linear correlation between the two. The model is then used to evaluate with precision, which of a selection of stiffeners, is needed to reduce pucker to an acceptable level, without overstifenning the seam. This work has implications in design and garment construction and manufacture, and in easy care garments. For the first time the idea of, precisely selecting a siffener so that it can locally to the seam alter the mechanics of the assembly, is introduced, as minimum intervention in the combat of seam puckering.     

The influence of two bar warp-knitted structure on the fabric tensile stress relaxation Part II: (locknit,satin, loop raised)

When strain is applied constantly, there is a decreased stress with time in viscoelastic materials, which is called stress relaxation. During the manufacture and application of clothing and footwear, materials experience various long-lasting deformations, and relaxation process in materials arises. Thus, with theoretical and experimental study of the factors affecting stress relaxation, the ability to design and produce appropriate clothes will be increased. In the first part of this research, we studied the stress relaxation behavior of warp-knitted structures which have longer underlaps in back bar (reverse locknit, three- and four-needle sharkskin, and queens’ cord). Following the previous research, the aim of this study was to investigate the effect of fabric structure, strain percentage, and course density on the stress and stress relaxation of the warp-knitted structures which have longer underlaps in front bar (locknit, three- and four-needle satin, and loop raised). The results reveal that the fabric structure, strain value, and fabric density are important factors affecting the stress and stress relaxation percent of the fabrics. By increasing the strain and the length of underlap in the front guide bar, stress and stress relaxation percent will be increased. Also, fabrics with higher course density show higher stress and stress relaxation percent. Among the mechanical models used to describe the stress relaxation behavior of the fabrics, the three-component Maxwell’s model with parallel-connect nonlinear spring showed the best agreement with the experimental stress relaxation curves of the analyzed fabrics.     

Metal flux and dynamic speciation at (bio)interfaces. Part II: Evaluation and compilation of physicochemical parameters for complexes with particles and aggregates

The computation of metal flux in aquatic systems at consuming surfaces like organism membranes must consider the diffusion processes of metal ions, ligands, and complex species, as well as the kinetic and thermodynamic aspects of their chemical interactions. Many natural ligands, however, have complicated properties (formation of successive complexes for simple ligands, polyelectrolytic properties and chemical heterogeneity for macromolecular ligands, large size distribution and fractal structure for suspended aggregates). These properties should be properly modeled to get the correct values of the chemical rate constants and diffusion coefficients required for flux computations. The selection of the most appropriate models and parameter values is far from straightforward. In this series of papers, models and compilations of parameters for application to the three most important types of complexants found in aquatic systems, the small, simple ligands, the fulvic and humic compounds, and the colloidal "particles" or aggregates, are discussed. In particular, new approaches are presented to compute the rate constants of metal complex formation for both fulvics/humics and particles/aggregates. A method to include the site distribution of fulvics/ humics and the size distribution of particles/aggregates in metal flux computation at consuming interfaces is also discussed in detail. These models and parameters are discussed critically and presented in a single consistent framework, applicable to the computation of metal flux in presence of any of the above complexants ortheir mixtures. Part I of the series focuses on simple ligands and fulvic/ humic compounds. Part II deals with particulate and aggregate complexants.     

Glycidyl esters in refined palm (Elaeis guineensis) oil and related fractions. Part II: Practical recommendations for effective mitigation

In a previous work, it was shown that at high temperatures (up to 280 °C) glycidyl esters (GE) are formed from diacylglycerols (DAG) via elimination of free fatty acid (FFA). In the present study, the impact of DAG content and temperature on the formation of GE using a model vacuum system mimicking industrial edible oil deodorization is investigated. These deodorization experiments confirmed that the formation of GE from DAG is extensive at temperatures above 230-240 °C, and therefore, this value should be considered as an upper limit for refining operations. Furthermore, experimental data suggest that the formation of GE accelerates in particular when the DAG levels in refined oils exceed 3-4% of total lipids. Analysis of the lipid composition of crude palm oil (CPO) samples allowed the estimation that this critical DAG content corresponds to about 1.9-2.5% of FFA, which is the conventional quality marker of CPO. Moreover, high levels (>100 ppm) of GE were also found in palm fatty acid distillate samples, which may indicate that the level of GE in fully refined palm oils also depends on the elimination rate of GE into the fatty acid distillate.     

The application of counter immunoelectrophoresis (CIE) in ocular protein studies Part II: Kinin activity in the lens wearing eye.

The kinin family are a group of bioactive peptides that are closely involved in the modulation of vascular inflammation and local injury. We have demonstrated here, for the first time, a link between kinin activity and contact lens wear. Protein extracts from daily and extended wear etafilcon A, Group IV, Acuvue lenses (Vistakon), were analysed by counter immunoelectrophoresis. In this way, kinin activity associated with contact lens wear was detected. High molecular weight kininogen was used as the marker protein. In contrast, no kinin activity was detected in the non-lens wearing normal eye.     

Role of transition metals,Fe(II), Cr(II), Pb(II), and Cd(II) in lipid peroxidation

Cod liver oil was oxidized with Fenton-like systems containing transition metals Fe(II), Cr(II), Pb(II), and Cd(II). Malonaldehyde (MA) formed from 10 μl cod liver oil oxidized by a Fenton-like system containing each metal at levels of 0.25, 0.5, 1 and 4 μmol was analyzed by a gas chromatograph equipped with a nitrogen phosphorus detector. The MA production exhibited dose response and the greatest amount (837.0 ± 19.1 nmol) was obtained by the Fe(II) system at the level of l μmol. Generally, higher MA formation is observed in the lower the third ionization potential of the metal. The decreasing order of MA formed in the metal systems at the level of 1 μmol is Fe(II) > Cr(II)(274.1 ± 20.1 nmol) > Pb(II)(150.7 ± 13.0 nmol) > Cd(II)(95.4 ± 6.7 nmol). The amounts of MA formed in Cr(II), Pb(II), and Cd(II) systems were considerably lower than those in the Fe(II) system. The relative formations of MA in the Cr(II) and Pb(II) systems were similar to those in the Fe(II) system. The results suggest that trace amounts of metals contribute oxidative effects to lipid peroxidation followed by various diseases.     

The formation and performance of auxetic textiles. Part II: geometry and structural properties

Some exceptional materials become fatter when stretched and are described as auxetics or having negative Poisson’s ratio. Auxetic textiles belong to this class of extraordinary materials that are increasingly attaining some prominence in many applications of technical textiles. We have sustained the efforts to fabricate auxetic fabric structures based on non‐auxetic yarns. The focus is to combine our knowledge of geometry and fabric structural characteristics to engineer auxetic textiles and to determine the properties of such auxetic textile fabrics. To realize our objective, we designed and investigated hexagonal knit structures as auxetic textiles offering optimum performance. The factors that influence Poisson’s ratio are identified as yarn type, number of chain courses and strain level. Also, a method has been developed for quantifying the geometrical structural unit cell of the auxetic structure based on measured parameters, namely a ₁, a ₂, b ₁, b ₂, h and c, as detailed in this paper.     

Role of dietary lipids and butylated hydroxy anisol (BHA) administration on albino rats. Part II. Liver and heart unsaturated fatty acids

Adult male albino rats were supplemented with edible plant oils, corn maize and cotton seed oils and their semihydrogenated forms (Heliopolis and Sultan cooking fat). In general, the supplementation of tested oils produced increasing effect on the levels of total unsaturated fatty acids (UFA), C18: 1, C18:2 and C20:4 UFA of liver and heart of rats. Liver content of UFA showed very highly significant increases in the levels of C18: 1 and C18:2 in all groups of rats fed with tested oils accompanied with non significant changes in total UFA and C20:4 levels. Heart content of UFA showed increases in the levels of C18: 1 and C18:2 and insignificant changes observed in total UFA and C20:4, except, in rats fed with sultan cooking fat, showed a significant increase in the level of total UFA. The level of increase in C18: 1 and C18:2 was very highly significant in case of rats fed corn maize oil and Sultan cooking fat, and significant in case of rats fed cotton seed oil and Heliopolis cooking fat. Also, liver and heart UFA contents were significantly increased after antioxidant (Butylated hydroxy anisol, BHA) administration. Addition of BHA to tested diets abolished or minimized fatty infiltration produced by dietary fatty diet in the liver cells.     

Synthesis,characterisation and analytical application of Fe3O4@SiO2@polyaminoquinoline magnetic nanocomposite for the extraction and pre-concentration of Cd(II) and Pb(II) in food samples

This work describes a novel Fe₃O₄@SiO₂@polyaminoquinoline magnetic nanocomposite and its application in the pre-concentration of Cd(II) and Pb(II) ions. The parameters affecting the pre-concentration procedure were optimised by a Box–Behnken design through response surface methodology. Three variables (extraction time, magnetic sorbent amount and pH) were selected as the main factors affecting the sorption step, while four variables (type, volume and concentration of the eluent, and elution time) were selected as main factors in the optimisation study of the elution step. Following the sorption and elution of analytes, the ions were quantified by flame atomic absorption spectrometry (FASS). The limits of detection were 0.1 and 0.7 ng ml^?1 for Cd(II) and Pb(II) ions, respectively. All the relative standard deviations were less than 7.6%. The sorption capacities of this new sorbent were 57 mg g^?1 for Cd(II) and 73 mg g^?1 for Pb(II). Ultimately, this nanocomposite was successfully applied to the rapid extraction of trace quantities of these heavy metal ions from seafood and agricultural samples and satisfactory results were obtained.