Structure and properties of starch-based foams prepared by microwave heating from extruded pellets

The physical properties of microwave-foamed starch-based pellets, including density, porosity, cell structure, water absorption characteristics and mechanical properties were characterized. It was found that the physical properties of these starch-based foams produced by microwave heating are highly dependent on the raw materials and additives. Foam density decreased significantly after addition of 5.5–10.5% w/w salts, while foams containing nucleation agent (talc) were denser than the control with reduced cell size. A proprietary blowing agent did not affect the foam density markedly. Addition of salts also increased the water sorption of foams and plasticized cell walls. Mechanical behaviour of foamed pellets can be adjusted effectively by controlling the cell structure through using different additives. Mechanical properties of the foamed pellets in the elastic region as well as under large deformation (up to 40% strain) all follow a power–law relationship with foam density.     

Effect of acid–alcohol treatment on the molecular structure and physicochemical properties of maize and potato starches

The molecular structure and physicochemical properties of acid–alcohol treated maize and potato starches (0.36% HCl in methanol at 25 °C for 1–15 days) were investigated. The yields of the modified starches were ranging from 91 to 100%. The average granule size of modified starches decreased slightly. The solubility of starches increased with the increase of treatment time, and the pasting properties confirmed the high solubility of modified starches. The gelatinization temperatures and range of gelatinization increased with the increase of treatment time except T_o (onset temperature) of maize starch. Molecular structures of modified starches suggested the degradation of starches occurred mostly within the first 5 days of treatment, and degradation rate of potato starch was higher than maize starch both in amylopectin and in amylose. Maize starch was found less susceptible to acid–alcohol degradation than potato starch.     

The dosage effect of the wildtype GBSS allele is linear for GBSS activity but not for amylose content: absence of amylose has a distinct influence on the physico-chemical properties of starch

A gene-dosage population was obtained by crossing two genotypes that were duplex for the GBSS allele. Nulliplex, simplex, duplex or triplex/quadruplex plants could be identified by monitoring the segregation of red and blue microspores after staining with iodine. GBSS activity was significantly different for all groups and showed an almost linear dosage effect for the wildtype GBSS gene. A dosage effect was found for amylose content that was not linear. The amylose content was similar for both the duplex and triplex/quadruplex group. Within the simplex group, differences in amylose content were found, which might be due to a different genetic background. There was no linear correlation between GBSS activity and amylose content. A certain level of GBSS activity led to a maximum amount of amylose, and further increase in GBSS activity did not result in a further increase in amylose content. The presence of one or more wildtype GBSS allele(s), and therefore the presence of amylose in the starch granules, had a great influence on the physico-chemical properties of the starch suspensions.     

基于CGE碳税政策对北京社会经济系统的影响分析

根据研究需要与北京市2010年投入产出表部门划分情况,尽可能地对能源部门进行细分,并编制社会核算矩阵。构建可计算一般均衡(CGE)模型模拟碳税政策对北京市社会经济的影响。实证结果显示:碳税政策具有显著的节能减排效果,对于化石能源密集型产业产出具有明显的抑制作用,但对于清洁能源、服务业等行业产出具有促进作用。因此严格限制煤炭、石油等高碳化石能源的使用、开发高碳能源低碳化利用技术是减排的重要措施。由于碳税会使产品价格上升,从而导致消费需求减少,碳税对国内生产总值和社会福利具有一定的负面影响,虽然影响程度的相对量有限,但影响的绝对效果较大,应该避免较高的碳税税率。     

Sporadic Creutzfeldt–Jakob disease subtype‐specific alterations of the brain proteome: Impact on Rab3a recycling

Sporadic Creutzfeldt–Jakob disease (sCJD) is characterized by wide clinical and pathological variability, which is mainly influenced by the conformation of the misfolded prion protein, and by the methionine and valine polymorphism at codon 129 of the prion protein gene. This heterogeneity likely implies differences in the molecular cascade that leads to the development of certain disease phenotypes. In this study, we investigated the proteome of the frontal cortex of patients with the two most common sCJD subtypes (MM1 and VV2) using 2D‐DIGE and MS. Analysis of 2D maps revealed that 46 proteins are differentially expressed in the sCJD. Common differential expression was detected for seven proteins, four showed opposite direction of differential expression, and the remaining ones displayed subtype‐specific alteration. The highest number of differentially expressed proteins was associated with signal transduction and neuronal activity. Moreover, functional groups of proteins involved in cell cycle and death, as well as in structure and motility included subtype‐specific expressed proteins exclusively. The expression of Rab GDP dissociation inhibitor alpha, which regulates Rab3a‐mediated neurotransmitter release, was affected in both sCJD subtypes that were analyzed. Therefore, we also investigated as to whether Rab3a recycling is altered. Indeed, we found an accumulation of the membrane‐associated form, thus the active one, which suggests that dysfunction of the Rab3a‐mediated exocytosis might be implicated in sCJD pathology.     

Analyses of the folding properties of ferredoxin‐like fold proteins by means of a coarse‐grained Gō model: Relationship between the free energy profiles and folding cores

The folding mechanisms of proteins with multi‐state transitions, the role of the intermediate states, and the precise mechanism how each transition occurs are significant on‐going research issues. In this study, we investigate ferredoxin‐like fold proteins which have a simple topology and multi‐state transitions. We analyze the folding processes by means of a coarse‐grained Gō model. We are able to reproduce the differences in the folding mechanisms between U1A, which has a high‐free‐energy intermediate state, and ADA2h and S6, which fold into the native structure through two‐state transitions. The folding pathways of U1A, ADA2h, S6, and the S6 circular permutant, S6_p54‐55, are reproduced and compared with experimental observations. We show that the ferredoxin‐like fold contains two common regions consisting folding cores as predicted in other studies and that U1A produces an intermediate state due to the distinct cooperative folding of each core. However, because one of the cores of S6 loses its cooperativity and the two cores of ADA2h are tightly coupled, these proteins fold into the native structure through a two‐state mechanism. Proteins 2014; 82:954–965. © 2013 Wiley Periodicals, Inc.     

Sensitive and selective determination of fluvoxamine maleate using a sensitive chemiluminescence system based on the alkaline permanganate–Rhodamine B–gold nanoparticles reaction

A high‐yield chemiluminescence (CL) system based on the alkaline permanganate–Rhodamine B reaction was developed for the sensitive determination of fluvoxamine maleate (Flu). Rhodamine B is oxidized by alkaline KMnO₄ and a weak CL emission is produced. It was demonstrated that gold nanoparticles greatly enhance this CL emission due to their interaction with Rhodamine B molecules. It is also observed that sodium dodecyl sulfate, an anionic surfactant, can strongly increase this enhancement. In addition, it was demonstrated that a notable decrease in the CL intensity is observed in the presence of Flu. This may be related to Flu oxidation with KMnO₄. There is a linear relationship between the decrease in CL intensity and the Flu concentration over a range of 2–300 µg/L. A new simple, rapid and sensitive CL method was developed for the determination of Flu with a detection limit (3s) of 1.35 µg/L. The proposed method was used for the determination of Flu in pharmaceutical and urine samples. Copyright © 2014 John Wiley & Sons, Ltd.     

The effects of spacer length on the fluorescence quantum yields of the benzofurazan compounds bearing a donor–acceptor system

We studied the effects of spacer length on the fluorescence quantum yields (Φ) of photoinduced electron transfer (PET) reagents, using nitrobenzoxadiazole (NBD) derivatives that have the –NMe₂ moiety and NBD–NH– fluorophore as electron donor (D) and electron acceptor (A), respectively. The Φ values were reduced as the spacer length became shorter (n ≤ 4; n is the number of methylene units of the spacer) and the fluorescence recovered by suppression of the PET process. It is necessary for the useful PET reagents to link D and A with a short spacer to obtain a difference in the Φ values between fluorescent ‘off‐state’ and ‘on‐state’. Copyright © 2002 John Wiley & Sons, Ltd.     

Analyzing the effect of decreasing cytosolic triosephosphate isomerase on Solanum tuberosum hairy root cells using a kinetic–metabolic model

A kinetic–metabolic model of Solanum tuberosum hairy roots is presented in the interest of understanding the effect on the plant cell metabolism of a 90% decrease in cytosolic triosephosphate isomerase (cTPI, EC 5.3.1.1) expression by antisense RNA. The model considers major metabolic pathways including glycolysis, pentose phosphate pathway, and TCA cycle, as well as anabolic reactions leading to lipids, nucleic acids, amino acids, and structural hexoses synthesis. Measurements were taken from shake flask cultures for six extracellular nutrients (sucrose, fructose, glucose, ammonia, nitrate, and inorganic phosphate) and 15 intracellular compounds including sugar phosphates (G6P, F6P, R5P, E4P) and organic acids (PYR, aKG, SUCC, FUM, MAL) and the six nutrients. From model simulations and experimental data it can be noted that plant cell metabolism redistributes metabolic fluxes to compensate for the cTPI decrease, leading to modifications in metabolites levels. Antisense roots showed increased exchanges between the pentose phosphate pathway and the glycolysis, an increased oxygen uptake and growth rate. Biotechnol. Bioeng. 2013; 110: 924–935. © 2012 Wiley Periodicals, Inc.     

Βeta-carotene protects sudan IV from photocatalytic degradation in a micellar model system: Insights into the antioxidant properties of the “golden” <Emphasis Type="Italic">Staphylococcus aureus</Emphasis>

Sterilization using titanium dioxide-mediated photocatalysis has been shown to be a powerful biocidal process due to the production of reactive redox species (RRS). More specifically, these RRS generated from TiO₂ photocatalysis are able to completely oxidize organic material, including microorganisms. Photocatalysis is a potentially useful application for the production of u.v.-illuminated self-sterilizing surfaces such as in surgical suites or water purification. Some organisms are able to protect themselves from radicals and oxidants by producing carotenoid pigments which scavenge free radicals and oxidants. In this work we have created a micellar model with a target dye and used the model to demonstrate that when β-carotene is incorporated into the system it will protect the target dye from photocatalytic destruction. Our model will help to predict how difficult it will be to destroy microbes when exposed to photocatalysis. Our data showed that 50% of the target dye was protected after 5 min of photocatalytic oxidation when β-carotene was present in the micellar system. However, when the micellar system lacked β-carotene protection, 82% of the dye was destroyed via photocatalysis. As a frame of reference, we subjected our model system to standard oxidative Fenton conditions namely, Fe(NO₃)₃/H₂O₂. We demonstrated that after 90 min exposure to the above reagents 80% of the target dye remained when β-carotene was present in the micellar system. However, when no β-carotene was present 62% of the dye was destroyed under Fenton conditions.     

Bioencapsulation of apomyoglobin in nanoporous organosilica sol–gel glasses: Influence of the siloxane network on the conformation and stability of a model protein

Nanoporous sol–gel glasses were used as host materials for the encapsulation of apomyoglobin, a model protein employed to probe in a rational manner the important factors that influence the protein conformation and stability in silica‐based materials. The transparent glasses were prepared from tetramethoxysilane (TMOS) and modified with a series of mono‐, di‐ and tri‐substituted alkoxysilanes, R_nSi(OCH₃)_4?n (R = methyl‐, n = 1; 2; 3) of different molar content (5, 10, 15%) to obtain the decrease of the siloxane linkage (? Si? O? Si? ). The conformation and thermal stability of apomyoglobin characterized by circular dichroism spectroscopy (CD) was related to the structure of the silica host matrix characterized by ²⁹Si MAS NMR and N₂ adsorption. We observed that the protein transits from an unfolded state in unmodified glass (TMOS) to a native‐like helical state in the organically modified glasses, but also that the secondary structure of the protein was enhanced by the decrease of the siloxane network with the methyl modification (n = 0 < n = 1 < n = 2 < n = 3; 0 < 5 < 10 < 15 mol %). In 15% trimethyl‐modified glass, the protein even reached a maximum molar helicity (?24,000 deg. cm² mol^?1) comparable to the stable folded heme‐bound holoprotein in solution. The protein conformation and stability induced by the change of its microlocal environment (surface hydration, crowding effects, microstructure of the host matrix) were discussed owing to this trend dependency. These results can have an important impact for the design of new efficient biomaterials (sensors or implanted devices) in which properly folded protein is necessary. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 895–906, 2009. This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com     

Chemiluminescence determination of moxifloxacin in pharmaceutical and biological samples based on its enhancing effect of the luminol–ferricyanide system using a microfluidic chip

A sensitive determination of a synthetic fluoroquinolone antibacterial agent, moxifloxacin (MOX), by an enhanced chemiluminescence (CL) method using a microfluidic chip is described. The microfluidic chip was fabricated by a soft‐lithographic procedure using polydimethyl siloxane (PDMS). The fabricated PDMS microfluidic chip had three‐inlet microchannels for introducing the sample, chemiluminescent reagent and oxidant, and a 500 µm wide, 250 µm deep and 82 mm long microchannel. An enhanced CL system, luminol–ferricyanide, was adopted to analyze the MOX concentration in a sample solution. CL light was emitted continuously after mixing luminol and ferricyanide in the presence of MOX on the PDMS microfluidic chip. The amount of MOX in the luminol–ferricyanide system influenced the intensity of the CL light. The linear range of MOX concentration was 0.14–55.0 ng/mL with a correlation coefficient of 0.9992. The limit of detection (LOD) and limit of quantification (LOQ) were 0.06 and 0.2 ng/mL respectively. The presented method afforded good reproducibility, with a relative standard deviation (RSD) of 1.05% for 10 ng/mL of MOX, and has been successfully applied for the determination of MOX in pharmaceutical and biological samples. Copyright © 2013 John Wiley & Sons, Ltd.     

Diversity and clade ages of West Indian hummingbirds and the largest plant clades dependent on them: a 5–9 Myr young mutualistic system

We analysed the geographical origins and divergence times of the West Indian hummingbirds, using a large clock‐dated phylogeny that included 14 of the 15 West Indian species and statistical biogeographical reconstruction. We also compiled a list of 101 West Indian plant species with hummingbird‐adapted flowers (90 of them endemic) and dated the most species‐rich genera or tribes, with together 41 hummingbird‐dependent species, namely Cestrum (seven spp.), Charianthus (six spp.), Gesnerieae (75 species, c. 14 of them hummingbird‐pollinated), Passiflora (ten species, one return to bat‐pollination) and Poitea (five spp.), to relate their ages to those of the bird species. Results imply that hummingbirds colonized the West Indies at least five times, from 6.6 Mya onwards, coming from South and Central America, and that there are five pairs of sister species that originated within the region. The oldest of the dated plant groups diversified 9.1, 8.5, and 5.4 Mya, simultaneous with or slightly before the extant West Indian bird radiations. The time frame of the coevolved bird/flower mutualisms obtained here resembles that recently inferred for North America, namely 5–9 Mya. © 2015 The Linnean Society of London, Biological Journal of the Linnean Society, 2015, 114 , 848–859.     

Impact of floral herbivory by <Emphasis Type="Italic">Coleotechnites eryngiella</Emphasis> Bottimer (Lepidoptera: Gelechiidae) on the reproductive output of <Emphasis Type="Italic">Eryngium yuccifolium</Emphasis> Michaux (Apiaceae): a test of the reserve ovary model

The reserve ovary model is a key hypothesis proposed to explain why plants produce surplus flowers and posits that plants may utilize surplus flowers to compensate for losses from floral herbivory. We tested this hypothesis in the prairie plant Eryngium yuccifolium and its floral herbivore Coleotechnites eryngiella. At five Illinois tallgrass prairie sites, we collected central, primary lateral, and secondary lateral inflorescences from E. yuccifolium to determine whether damage by the larvae of C. eryngiella to the flowers in earlier developing inflorescences would be compensated for in later developing inflorescences. Coleotechnites eryngiella does extensive damage to the central and primary inflorescences and little damage to the secondary inflorescences. Later maturing inflorescences did not compensate for early damage by increasing seed production in later inflorescences. The secondary inflorescences of E. yuccifolium may only compensate for catastrophic damage done to the central and primary inflorescences early on in development, serve as additional advertisements for pollinators, act as pollen donors, or allow the plant to take advantage of “ecological windows” of high pollinator and low herbivore abundance. Our findings were spatially and temporally consistent and did not support the predictions of the reserve ovary model in the E. yuccifolium–C. eryngiella system suggesting that in this system, alternate, proximate, and ultimate causes need to be explored for the production of surplus flowers.