Understanding the role of cross-link density in the segmental dynamics and elastic properties of cross-linked thermosets.

Cross-linking is known to play a pivotal role in the relaxation dynamics and mechanical properties of thermoset polymers, which are commonly used in structural applications because of their light weight and inherently strong nature. Here, we employ a coarse-grained (CG) polymer model to systematically explore the effect of cross-link density on basic thermodynamic properties as well as corresponding changes in the segmental dynamics and elastic properties of these network materials upon approaching their glass transition temperatures (Tg). Increasing the cross-link density unsurprisingly leads to a significant slowing down of the segmental dynamics, and the fragility K of glass formation shifts in lockstep with Tg, as often found in linear polymer melts when the polymer mass is varied. As a consequence, the segmental relaxation time τα becomes almost a universal function of reduced temperature, (T - Tg)/Tg, a phenomenon that underlies the applicability of the "universal" Williams-Landel-Ferry (WLF) relation to many polymer materials. We also test a mathematical model of the temperature dependence of the linear elastic moduli based on a simple rigidity percolation theory and quantify the fluctuations in the local stiffness of the network material. The moduli and distribution of the local stiffness likewise exhibit a universal scaling behavior for materials having different cross-link densities but fixed (T - Tg)/Tg. Evidently, Tg dominates both τα and the mechanical properties of our model cross-linked polymer materials. Our work provides physical insights into how the cross-link density affects glass formation, aiding in the design of cross-linked thermosets and other structurally complex glass-forming materials.

SET and HAT/PCET acid-mediated oxidation processes in helical shaped fused bis-phenothiazines.

Helical shaped fused bis-phenothiazines 1-9 have been prepared and their red-ox behaviour quantitatively studied. Helicene radical cations (Hel.+ ) can be obtained either by UV-irradiation in the presence of PhCl or by chemical oxidation. The latter process is extremely sensitive to the presence of acids in the medium with molecular oxygen becoming a good single electron transfer (SET) oxidant. The reaction of hydroxy substituted helicenes 5-9 with peroxyl radicals (ROO. ) occurs with a 'classical' HAT process giving HelO. radicals with kinetics depending upon the substitution pattern of the aromatic rings. In the presence of acetic acid, a fast medium-promoted proton-coupled electron transfer (PCET) process takes place with formation of HelO. radicals possibly also via a helicene radical cation intermediate. Remarkably, also helicenes 1-4, lacking phenoxyl groups, in the presence of acetic acid react with peroxyl radicals through a medium-promoted PCET mechanism with formation of the radical cations Hel.+ . Along with the synthesis, EPR studies of radicals and radical cations, BDE of Hel-OH group (BDEOH ), and kinetic constants (kinh ) of the reactions with ROO. species of helicenes 1-9 have been measured and calculated to afford a complete rationalization of the redox behaviour of these appealing chiral compounds.

Absolute Antioxidant Activity of Five Phenol-Rich Essential Oils.

Essential oils (EOs) have promising antioxidant activities which are gaining interest as natural alternatives to synthetic antioxidants in the food and cosmetic industries. However, quantitative data on chain-breaking activity and on the kinetics of peroxyl radical trapping are missing. Five phenol-rich EOs were analyzed by GC-MS and studied by oxygen-uptake kinetics in inhibited controlled autoxidations of reference substrates (cumene and squalene). Terpene-rich Thymus vulgaris (thymol 4%; carvacrol 33.9%), Origanum vulgare, (thymol 0.4%; carvacrol 66.2%) and Satureja hortensis, (thymol 1.7%; carvacrol 46.6%), had apparent kinh (30 °C, PhCl) of (1.5 ± 0.3) × 104, (1.3 ± 0.1) × 104 and (1.1 ± 0.3) × 104 M-1s-1, respectively, while phenylpropanoid-rich Eugenia caryophyllus (eugenol 80.8%) and Cinnamomum zeylanicum, (eugenol 81.4%) showed apparent kinh (30 °C, PhCl) of (5.0 ± 0.1) × 103 and (4.9 ± 0.3) × 103 M-1s-1, respectively. All EOs already granted good antioxidant protection of cumene at a concentration of 1 ppm (1 mg/L), the duration being proportional to their phenolic content, which dictated their antioxidant behavior. They also afforded excellent protection of squalene after adjusting their concentration (100 mg/L) to account for the much higher oxidizability of this substrate. All investigated EOs had kinh comparable to synthetic butylated hydroxytoluene (BHT) were are eligible to replace it in the protection of food or cosmetic products.

Hydrogen Atom Transfer from HOO. to ortho-Quinones Explains the Antioxidant Activity of Polydopamine.

Melanins are stable and non-toxic biomaterials with a great potential as chemopreventive agents for diseases connected with oxidative stress, but the mechanism of their antioxidant action is unclear. Herein, we show that polydopamine (PDA), a well-known synthetic melanin, becomes an excellent trap for alkylperoxyl radicals (ROO. , typically formed during autoxidation of lipid substrates) in the presence of hydroperoxyl radicals (HOO. ). The key reaction explaining this peculiar antioxidant activity is the reduction of the ortho-quinone moieties present in PDA by the reaction with HOO. . This reaction occurs via a H-atom transfer mechanism, as demonstrated by the large kinetic solvent effect of the reaction of a model quinone (3,5-di-tert-butyl-1,2-benzoquinone) with HOO. (k=1.5×107 and 1.1×105  M-1 s-1 in PhCl and MeCN). The chemistry disclosed herein is an important step to rationalize the redox-mediated bioactivity of melanins and of quinones.

Regulation of compound leaf development in mungbean (Vigna radiata L.) by CUP-SHAPED COTYLEDON/NO APICAL MERISTEM (CUC/NAM) gene.

MAIN CONCLUSION: The results provide a significant verification of functional redundancy and diversity of CUC/NAM genes in legumes. The CUP-SHAPED COTYLEDON/NO APICAL MERISTEM (CUC/NAM) orthologs play key roles for plant organ boundary formation and organ development. Here, we performed a forward screen of the gamma irradiation mutagenesis population in mungbean and characterised a mutant, reduced rachis and fused leaflets (rrf1), which gave rise to the formation of compound leaves with reduced rachis and fused leaflets. Map-based cloning revealed that RRF1 encoded a CUC/NAM protein in mungbean. Phylogenetic analysis indicated that legume CUC1/CUC2 genes were classified as belonging to two subclades, and there are different copies of CUC1/CUC2 genes in legumes. Transcriptomic analysis showed that expression levels of a set of developmental regulators, including class I KNOTTED-LIKE HOMEOBOXI (KNOXI) gene and LATERAL ORGAN BOUNDARIES DOMAIN (LBD) gene, were altered in rrf1 mutants compared to the wild-type plants. Furthermore, rrf1 genetically interacted with heptafoliate leaflets1 (hel1), a mutant displaying a seven-leaflet compound leaf, to regulate leaf development in mungbean. Our results suggest functional redundancy and diversity of two subclades of CUC1/CUC2 genes in legumes, following the duplication of an ancestral gene.

Photomultiplier tube calibration based on Na lidar observation and its effect on heat flux bias.

Na lidar can measure vertical wind and temperature at high temporal and vertical resolutions, enough to resolve gravity wave perturbations. Heat flux due to dissipating gravity waves is an important quantity that can be derived from such perturbations. When lidar signals are high, a photomultiplier tube (PMT) used to count incoming photons may suffer from the saturation effect, and its output count is not linearly related to incoming photon counts. Corrections to this effect can be measured in a laboratory setting but may have large errors at high count rates. We show that the errors in the PMT correction can cause significant bias in the heat flux calculation due to the inherent correlation between wind and temperature errors. Using the measurements made by Na lidar at the Andes Lidar Observatory with Hamamatsu PMTs, we developed a calibration procedure to remove such PMT correction errors from laboratory measurements. By applying the revised PMT correction curve we demonstrated that the heat flux bias can be removed through this procedure.

A molecular dynamics study of bond exchange reactions in covalent adaptable networks.

Covalent adaptable networks are polymers that can alter the arrangement of network connections by bond exchange reactions where an active unit attaches to an existing bond then kicks off its pre-existing peer to form a new bond. When the polymer is stretched, bond exchange reactions lead to stress relaxation and plastic deformation, or the so-called reforming. In addition, two pieces of polymers can be rejoined together without introducing additional monomers or chemicals on the interface, enabling welding and reprocessing. Although covalent adaptable networks have been researched extensively in the past, knowledge about the macromolecular level network alternations is limited. In this study, molecular dynamics simulations are used to investigate the macromolecular details of bond exchange reactions in a recently reported epoxy system. An algorithm for bond exchange reactions is first developed and applied to study a crosslinking network formed by epoxy resin DGEBA with the crosslinking agent tricarballylic acid. The trace of the active units is tracked to show the migration of these units within the network. Network properties, such as the distance between two neighboring crosslink sites, the chain angle, and the initial modulus, are examined after each iteration of the bond exchange reactions to provide detailed information about how material behaviors and macromolecular structure evolve. Stress relaxation simulations are also conducted. It is found that even though bond exchange reactions change the macroscopic shape of the network, microscopic network characteristic features, such as the distance between two neighboring crosslink sites and the chain angle, relax back to the unstretched isotropic state. Comparison with a recent scaling theory also shows good agreement.

Suppressive Effect of Matrine on Tumor Invasion in N-Butyl-N-(4-Hydroxybutyl)Nitrosamine-Induced Urinary Bladder Carcinogenesis.

AIMS: This study was designed to investigate the mechanisms and suppressive effects of matrine on the development of urinary bladder cancers induced by N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in rats. METHODS: Male Sprague-Dawley rats were given BBN (200 mg/rat) twice a week for a period of 8 weeks. Oral administration of matrine (50 and 100 mg/kg) was started 1 week before BBN exposure for 35 weeks. Half of each bladder was histopathologically analyzed and the remainder was extracted for protein analysis by Western blot. RESULTS: The bladders of BBN-treated rats demonstrated progression from epithelial hyperplasia to papillary urothelial neoplasia and even poorly differentiated invasive cancer. Matrine (50 and 100 mg/kg) treatment decreased the formation of large bladder tumors by 31.6 and 21.1%, respectively. An incidence of cancer cells was detected in rats given BBN [70% (14/20)] and matrine [50 mg/kg: 68.4% (13/19) and 100 mg/kg: 57.9% (11/19), respectively]. The frequency of invasive tumors in the matrine treatment groups [50 mg/kg: 15.4% (2/13), 100 mg/kg: 9.1% (1/11)] was significantly lower than in the BBN-alone group [57% (8/14)]. Furthermore, oral administration of matrine (50 and 100 mg/kg) markedly attenuated the BBN-induced upregulation of bladder cyclooxygenase-2 (COX-2) expression and the elevation of bladder cytosolic phospholipase A2 (cPLA2) levels. Although the contents of 15-prostaglandin dehydrogenase (PGDH), which degrades PGE2, were dramatically reduced by BBN, matrine exerted no effects on reduced PGDH contents. CONCLUSION: Our results suggest that matrine suppressed bladder tumor invasion in a rat model, and this might be primarily mediated through regulation of the protein contents, COX-2 and cPLA2 in the bladder.

Absolute kinetics of peroxidation and antioxidant protection of intact triglyceride vegetable oils.

To verfy their difference from isolated fatty acids, the absolute kinetics of peroxidation was studied for seven triglyceride-based oils of olive (OLI-1, OLI-2), high-oleic sunflower (SUN-HO), high-oleic and high-linoleic safflower (SAF-HO, SAF-HL) grapeseed (GRA) and borage (BOR), by oxygen uptake monitoring, using 2,6-di-tert-butyl-4-methoxyphenol and 2,2,5,7,8-pentamethyl-6-chromanol as reference inhibitors. Propagation constants (kp/M-1 s-1 at 303 K in PhCl) were respectively 34.8 ± 2.3, 35.1 ± 1.8, 40.6 ± 5.5, 36.0 ± 7.7, 160.8 ± 5.1, 145.1 ± 24.5, 275.1 ± 63.8, while oxidizability responded to empirical equation kp(2kt)-½/M-½s-½ = 1.63 × 10-3[allyl >CH2/M] + 1.82 × 10-2[bisallyl >CH2/M], based on fatty acids residues assessed by GC-MS. Peroxidation kinetics was markedly different from that of isolated fatty acids. The H-bond basicity of all oils was measured by FT-IR affording Abraham's ßH2 values in the range 0.55 ± 0.03. H-bonding explained the protection of oils measured for seven reference phenolic antioxidants, except for the catechols quercetin and caffeic acid phenethyl ester, which were 2-to-4-folds more effective than expected, supporting a proposed different mechanism.

Mechanism of Strength Formation of Unfired Bricks Composed of Aeolian Sand-Loess Composite.

Aeolian sand and loess are both natural materials with poor engineering-related properties, and no research has been devoted to exploring aeolian sand-loess composite materials. In this study, we used aeolian sand and loess as the main raw materials to prepare unfired bricks by using the pressing method, along with cement, fly ash, and polypropylene fiber. The effects of different preparation conditions on the physical properties of the unfired bricks were investigated based on compressive strength, water absorption, and softening tests and a freeze-thaw cycle test combined with X-ray diffraction and scanning electron microscope analysis to determine the optimal mixing ratio for unfired bricks, and finally, the effects of fibers on the durability of the unfired bricks were investigated. The results reveal that the optimal mixing ratio of the masses of aeolian sand-loess -cement -fly ash-polypropylene fiber-alkali activator-water was 56.10:28.05:9.17:2.40:0.4:0.003:4.24 under a forming pressure of 20 MPa. The composite unfired bricks prepared had a compressive strength of 14.5 MPa at 14 d, with a rate of water absorption of 8.8%, coefficient of softening of 0.92, and rates of the losses of frozen strength and mass of 15.93% and 1.06%, respectively, where these satisfied the requirements of environmentally protective bricks with strength grades of MU10-MU15. During the curing process, silicate and sodium silicate gels tightly connected the particles of aeolian sand and the loess skeleton, and the spatial network formed by the addition of the fibers inhibited the deformation of soil and improved the strength of the unfired bricks.

Establishment and Application of a Novel Genetic Detection Panel for SNPs in Mongolian Gerbils.

The Mongolian gerbil is a distinctive experimental animal in China, as its genetic qualities possess significant value in the field of medical biology research. Here, we aimed to establish an economical and efficient panel for genetic quality detection in Mongolian gerbils using single-nucleotide polymorphism (SNP) markers. To search for SNPs, we conducted whole-genome sequencing (WGS) in 40 Mongolian gerbils from outbred populations. Reliable screening criteria were established to preliminarily select SNPs with a wide genome distribution and high levels of polymorphism. Subsequently, a multiple-target regional capture detection system based on second-generation sequencing was developed for SNP genotyping. Based on the results of WGS, 219 SNPs were preliminarily selected, and they were established and optimized in a multiple-amplification system that included 206 SNP loci by genotyping three outbred populations. PopGen.32 analysis revealed that the average effective allele number, Shannon index, observed heterozygosity, expected heterozygosity, average heterozygosity, polymorphism information content, and other population genetic parameters of the Capital Medical University (CMU) gerbils were the highest, followed by those of Zhejiang gerbils and Dalian gerbils. Through scientific screening and optimization, we successfully established a novel, robust, and cost-effective genetic detection system for Mongolian gerbils by utilizing SNP markers for the first time.

The Tunable Rhenium Effect on the Creep Properties of a Nickel-Based Superalloy.

Atomistic simulations on the creep of a nickel-based single-crystal superalloy are performed for examining whether the so-called rhenium effect can be tuned by changing the spatial distribution of rhenium in the nickel matrix phase. Results show that Rhenium dopants at {100} phase interfaces facilitate mobile partial dislocations, which intensify the creep, leading to a larger creep strain than that of a pure Ni/Ni3Al system containing no alloying dopants. If all the Re dopants in the matrix phase are far away from phase interfaces, a conventional retarding effect of Re can be observed. The current study implies a tunable Re effect on creep via dislocation triggering at the phase interfaces.

Tandem Hydroperoxyl-Alkylperoxyl Radical Quenching by an Engineered Nanoporous Cerium Oxide Nanoparticle Macrostructure (NCeONP): Toward Efficient Solid-State Autoxidation Inhibitors.

The use of nanomaterials as inhibitors of the autoxidation of organic materials is attracting tremendous interest in petrochemistry, food storage, and biomedical applications. Metal oxide materials and CeO2 in particular represent one of the most investigated inorganic materials with promising radical trapping and antioxidant abilities. However, despite the importance, examples of the CeO2 material's ability to retard the autoxidation of organic substrates are still lacking, together with a plausible chemical mechanism for radical trapping. Herein, we report the synthesis of a new CeO2-derived nanoporous material (NCeONP) with excellent autoxidation inhibiting properties due to its ability to catalyze the cross-dismutation of alkyl peroxyl (ROO•) and hydroperoxyl (HOO•) radicals, generated in the system by the addition of the pro-aromatic hydrocarbon γ-terpinene. The antioxidant ability of NCeONP is superior to that of other nanosized metal oxides, including TiO2, ZnO, ZrO2, and pristine CeO2 nanoparticles. Studies of the reaction with a sacrificial reductant allowed us to propose a mechanism of inhibition consisting of H atom transfer from HOO• to the metal oxides (MOx + HOO• → MOx-H• + O2), followed by the release of the H atom to an ROO• radical (MOx-H• + ROO• → MOx + ROOH). Besides identifying NCeONP as a promising material for developing effective antioxidants, our study provides the first evidence of a radical mechanism that can be exploited to develop novel solid-state autoxidation inhibitors.

Real-time oxygen sensing as a powerful tool to investigate tyrosinase kinetics allows revising mechanism and activity of inhibition by glabridin.

A new method for studying tyrosinase kinetics and inhibition by oxygen sensing is described and matched to the conventional spectrophotometric approach. The stoichiometric ratio of O2 uptake to dopachrome formation was 1.5 ±â€¯0.2 for substrate l-tyrosine and 1.0 ±â€¯0.1 for l-DOPA. With both methods, we reinvestigated mushroom tyrosinase inhibition by glabridin from Glycyrrhiza glabra. The two methods agreed showing mixed-type inhibition for monophenolase and diphenolase activities, at variance with previous literature. Average KI (KSI) values for glabridin were 13.6 ±â€¯3.5 (281 ±â€¯89) nM and 57 ±â€¯8 (1312 ±â€¯550) nM, for monophenolase and diphenolase inhibition, respectively, with IC50 of 80 ±â€¯8 nM and 294 ±â€¯25 nM, respectively, at 1 mM substrate. For reference kojic acid KI (KSI) were 10.9 ±â€¯8 (217 ±â€¯55) µM and 9.9 ±â€¯1.4 (21.0 ±â€¯5.2) µM, for monophenolase and diphenolase, respectively, with respective IC50 of 33 ±â€¯8 µM and 17 ±â€¯3 µM. Glabridin's activity is among the highest in nature, being about three orders of magnitude higher than previously reported.

Efficacy of Chinese herbal medicine Jiangniaosuan formula for treatment of hyperuricemia: study protocol for a double-blinded non-inferiority randomized controlled clinical trial.

BACKGROUND: Jiangniaosuan formula (JNSF) is commonly used in China for treating hyperuricemia, but there is little research-based evidence to support its use. This randomized controlled trial aims to assess the efficacy and safety of JNSF. METHODS: A total of 72 patients with hyperuricemia will be selected and randomly assigned in a ratio of 1:2 to receive either Western medicine, i.e., febuxostat 40 mg (WG group; n = 24), or Chinese herbal medicine, i.e., Jiangniaosuan formula + febuxostat 20 mg (WJNSG group; n = 48). After 12 weeks, the WJNSG will be randomly divided into two groups of 24 patients each; one group (WJNSG; n = 24) still will receive febuxostat 20 mg + Jiangniaosuan formula, and the other group (JNSG; n = 24) will continue to receive Jiangniaosuan formula + placebo. Participants will be followed up at 4-week intervals. The primary outcome will be the change in serum uric acid level, and the secondary outcome will be the change in traditional Chinese medicine (TCM) syndrome scores. Serum creatinine, blood glucose, and insulin levels will also be measured. DISCUSSION: We hypothesize that patients with hyperuricemia will benefit from JNSF. This study will provide evidence-based recommendations for clinicians. DISSEMINATION: The results will be published in a peer-reviewed journal and disseminated by academic conferences. The datasets analyzed during the current study are available from the corresponding author on reasonable request. TRIAL REGISTRATION: Chinese Clinical Trials Register ChiCTR2000041083 . Registered on 3 May 2021. The protocol version number is V3.0, 20210301.

Synergic antioxidant activity of γ-terpinene with phenols and polyphenols enabled by hydroperoxyl radicals.

Antioxidant interactions of γ-terpinene with α-tocopherol mimic 2,2,5,7,8-pentamethyl-6-chromanol (PMHC) and caffeic acid phenethyl ester (CAPE), used as models, respectively, of mono- and poly-phenols were demonstrated by differential oximetry during the inhibited autoxidation of model substrates: stripped sunflower oil, squalene, and styrene. With all substrates, γ-terpinene acts synergistically regenerating the chain-breaking antioxidants PMHC and CAPE from their radicals, via the formation of hydroperoxyl radicals. The inhibition duration for mixtures PMHC/γ-terpinene and CAPE/γ-terpinene increased with γ-terpinene concentration, while rate constants for radical-trapping were unchanged by γ-terpinene, being 3.1 × 106 and 4.8 × 105 M-1s-1 for PMHC and CAPE in chlorobenzene (30 °C). Using 3,5-di-tert-butylcatechol and 3,5-di-tert-butyl-1,2-bezoquinone we demonstrate that γ-terpinene can reduce quinones to catechols enabling their antioxidant activity. The different synergy mechanism of γ-terpinene with mono- and poly-phenolic antioxidants is discussed and its relevance is proven in homogenous lipids using natural α-tocopherol and hydroxytyrosol as antioxidants, calling for further studies in heterogenous food products.

The Plastic Deformation Mechanisms of hcp Single Crystals with Different Orientations: Molecular Dynamics Simulations.

The deformation mechanisms of Mg, Zr, and Ti single crystals with different orientations are systematically studied by using molecular dynamics simulations. The affecting factors for the plasticity of hexagonal close-packed (hcp) metals are investigated. The results show that the basal dislocation, prismatic dislocation, and pyramidal dislocation are activated in Mg, Zr, and Ti single crystals. The prior slip system is determined by the combined effect of the Schmid factor and the critical resolved shear stresses (CRSS). Twinning plays a crucial role during plastic deformation since basal and prismatic slips are limited. The 101¯2 twinning is popularly observed in Mg, Zr, and Ti due to its low CRSS. The 101¯1 twin appears in Mg and Ti, but not in Zr because of the high CRSS. The stress-induced hcp-fcc phase transformation occurs in Ti, which is achieved by successive glide of Shockley partial dislocations on basal planes. More types of plastic deformation mechanisms (including the cross-slip, double twins, and hcp-fcc phase transformation) are activated in Ti than in Mg and Zr. Multiple deformation mechanisms coordinate with each other, resulting in the higher strength and good ductility of Ti. The simulation results agree well with the related experimental observation.

[Effect of Serum Free Light Chain Ratio and Normalization Ratio after Treatment on Diagnosis and Prognosis of Patients with Newly Diagnosed Multiple Myeloma].

OBJECTIVE: To evaluate the value of serum free light chain (sFLC) κ/λ ratio (sFLCR) on the diagnosis and prognosis of patients with newly diagnosed multiple myeloma(MM), and explore the effect of sFLCR normalization on the prognosis of patients after 4 courses of induction therapy. METHODS: The clinical data of 43 newly diagnosed MM patients from January 2014 to January 2019 were analyzed retrospectively. Immunoturbidimetry was used to detect the expression levels of sFLC κ and λ. According to the ratio of involved and uninvolved sFLC, using 100 as a boundary, the MM patients were divided into the high ratio group (sFLCR≥100 or ≤0.01) and the low ratio group (0.010.05). CONCLUSION: Patients in the high ratio group at the initial diagnosis have worse renal function, later stage of disease, lower deep remission rate, earlier disease progression, shorter survival time, and worse clinical prognosis.

The root iron transporter 1 governs cadmium uptake in Vicia sativa roots.

Cadmium is a non-essential element for plants and that inhibits plant growth and development. The Zhangye Mawan (ZM) variety of Vicia sativa is more sensitive to Cd toxicity than that Lanjian 3# (L3) variety, but the underlying mechanism is not fully understood. Here, we demonstrated that ZM showed higher Cd accumulation than L3 based on root Cd content and Cd fluorescence intensity in root protoplasts. VsRIT1, a member of the ZIP (ZRT/IRT-like protein) family, showed expression levels in ZM roots 8-fold higher than those in L3 roots under Cd exposure. VsRIT1 expression increased Cd transport and accumulation in Arabidopsis and yeast. These suggests that VsRIT1 participates in Cd uptake by V. sativa roots. Furthermore, ZM root tips have a higher capacity for transient Cd influx than L3 roots when exposed to Cd alone or Cd and iron (Fe) together, owing to the higher VsRIT1 expression in ZM. Our findings also imply that Cd may compete with Fe or/and zinc (Zn) for uptake via VsRIT1 in V. sativa or yeast.

Calibration of Squalene, p-Cymene, and Sunflower Oil as Standard Oxidizable Substrates for Quantitative Antioxidant Testing.

The autoxidation kinetics of stripped sunflower oil (SSO), squalene (SQ), and p-cymene ( p-C) initiated by 2,2'-azobis(isobutyronitrile) at 303 K were investigated under controlled conditions by differential oximetry in order to build reference model systems that are representative of the natural variability of oxidizable materials, for quantitative antioxidant testing. Rate constants for oxidative chain propagation ( kp) and chain termination (2 kt) and the oxidizability ( kp/√2 kt) were measured using 2,6-di- tert-butyl-4-methoxyphenol, 2,2,5,7,8-pentamethyl-6-chromanol, BHT, and 4-methoxyphenol as reference antioxidants. Measured values of kp (M-1 s-1)/2 kt (M-1 s-1)/oxidizability (M-1/2 s-1/2) at 303 K in chlorobenzene were 66.9/3.45 × 106/3.6 × 10-2, 68.0/7.40 × 106/2.5 × 10-2, and 0.83/2.87 × 106/4.9 × 10-4, respectively, for SSO, SQ, and p-C. Quercetin, magnolol, caffeic acid phenethyl ester, and 2,4,6-trimethylphenol were investigated to validate calibrations. The distinctive usefulness of the three substrates in testing antioxidants is discussed.