THERMAL DEGRADATION AND FLAME RETARDANCY OF CALCIUM ALGINATE FIBERS

Calcium alginate fibers were prepared by wet spinning of sodium alginate into a coagulating bath containing calcium chloride.The thermal degradation and flame retardancy of calcium alginate fibers were investigated with thermal gravimetry(TG),X-ray diffraction(XRD),limiting oxygen index(LOI) and cone calorimeter(CONE).The results show that calcium alginate fibers are inherently flame retardant with a LOI value of 34,and the heat release rate(HRR),total heat release(THR),CO and CO_2 concentrations during com...

CHEMICAL MODIFICATION OF THE SURFACE OF CALCIUM ALGINATE GEL BEADS

The chemical modification of the surface of calcium alginate gel beads (CAGB) via grafting copolymerization with vinyl acetate (VAc) was studied. The optimum reaction conditions with activation and graft copolymerization two steps were explored. First, 5 grams CAGB with 2.5 mm initial diameter was initiated with 0.0493 mol/L K2S2O8 at 51 °C for 30 min in 15 mL 1 % PVA/H2O. Then 4.34 moi/L VAc was added dropwise and the reaction was allowed to proce at 48 °C for 3 h. The grafting efficiency could come up to 30%. It was found the stability of modified CAGB in the air and in electrolyte solutions was greatly improved.

Production of Indigo by Immobilization of E. coli BL21 （DE3） Cells in Calcium-Alginate Gel Capsules

The ability of catalyzing indole into indigo of gene engineering strain expressing P450 BM3 immobi- lized by entrapment in calcium-alginate gel capsules was examined,and various characteristics of immobilized cells were assessed.Optimum conditions for cells activity were not affected after immobilization,and pH and tempera- ture for both free and immobilized cells were found to be pH 7.5 and 35℃,respectively.The immobilized cells ex- hibited a markedly improved thermal stability than free cells.After five repeated experiments,the yield of indigo with the immobilized cells retained over 94%of their original activity,which indicated that the operational stability for recycling in batch processes was improved.

Preparation and Characterization of Ferromagnetic Calcium Alginate Complex Gel

Fe3O4 suspension, derived from chemical coprecipitation and subsequent ultrasonic treatment, was embedded into calcium alginate to form complex gel. Both gel beads and injectable gel floc were obtained by slightly tailoring the preparation condition. SEM analysis showed that the iron oxide was dispersed homogenously in nanometer. TGA profiles revealed that the content of Fe3O4 in beads was about 7.2%.

Recent advances in calcium alginate hydrogels encapsulating rejuvenator for asphalt self-healing

The inherent self-healing ability of asphalt is insufficient and fails to timely repair the cracks due to the combined effect of temperature variation,air oxidation,ultraviolet exposure and traffic loading.Rejuvenator encapsulation based on self-healing asphalt is a green sustainable preventive maintenance technology for asphalt pavement.During the last decade,rejuvenator encapsulation for asphalt self-healing has been a research hotspot and calcium alginate hydrogels encapsulating rejuvenator is a promising self-healing technology.Hence,this review sheds light on the recent advances of calcium alginate hydrogels encapsulating asphalt rejuvenator including selfhealing capsules and fibers.The synthesis methods of calcium alginate capsules and fibers containing rejuvenator were elaborately introduced,and their surface morphology,interior structure,mechanical strength,thermal stability,rejuvenator content,distribution and survival in asphalt materials were systematically analyzed.Besides,the effect of capsules and fiber on the mechanical property and pavement performance of asphalt concrete were explored.Additionally,a comprehensive review about the effect of calcium alginate capsules and fibers on selfhealing ability of asphalt materials were presented,and the rejuvenator release mechanism and release ratio of them in asphalt mixtures were expounded.In a nutshell,this review aims at highlighting the current research achievements on alginate capsules and fibers containing rejuvenator in asphalt materials,and inspiring enhanced self-healing methods for smart and sustainable maintenance of asphalt pavement.

Physicochemical properties and release characteristics of calcium alginate microspheres loaded with Trichoderma viride spores

Novel agroformulations for simultaneous delivery of chemical and biologically active agents to the plants were prepared by encapsulation of Trichoderma viride spores in calcium alginate microspheres.The impact of calcium ions concentration on the viability and sporulation of T.viride spores as well as on the microsphere important physicochemical properties were investigated.Intermolecular interactions in microspheres are complex including mainly hydrogen bonds and electrostatic interactions.T.viride germination inside matrix and germ tubes penetration out of microspheres revealed calcium alginate microspheres provide a supportive environment for T.viride growth.Differences in physicochemical properties and bioactive agents release behaviour from microspheres were ascribed to the changes in microsphere structure.Fitting to Korsmeyer-Peppas empirical model revealed the underlying T.viride release mechanism as anomalous transport kinetics(a combination of two diffusion mechanisms and the Type II transport(polymer swelling and relaxation of the polymeric matrix)).The increasing amount of T.viride spores in the surrounding medium is closely related to the release from microspheres and germination.The rate controlling mechanism of calcium release is Fickian diffusion.A decrease in the release rate with increasing calcium ion concentrations is in accordance with the calcium ions effect on the strength of the alginate network structure.T.viride germination inside microsphere diminished the amount of released calcium ions and slowed release kinetics in comparison with microspheres prepared without T.viride.The results indicated investigated agroformulations have a great potential to be used for plant protection and nutrition.

A new size and shape controlling method for producing calcium alginate beads with immobilized proteins

A method for producing size- and shape-con-trolled calcium alginate beads with immobilized proteins was developed. Unlike previous cal-cium alginate bead production methods, pro-tein-immobilized alginate beads with uniform shape and sizes less then 20 micrometers in diameter could successfully be produced by using sonic vibration. BSA and FITC-conjugated anti-BSA antibodies were used to confirm pro-tein immobilization in the alginate beads. Pro-tein diffusion from the beads could be reduced to less than 10% by cross-linking the proteins to the alginate with 1-ethyl-3-(3-dimethylamino-propyl)carbodiimide (EDC) and N-hydroxysul-fosuccinimide (NHSS). The calcium alginate beads could also be arranged freely on a slide glass by using a femtosecond laser.

Effect of calcium alginate dressing on the cytokine contents,collagen synthesis-degradation balance and apoptosis gene expression in the wound after perianal abscess surgery

Objective: To study the effect of calcium alginate dressing on the cytokine contents, collagen synthesis - degradation balance and apoptosis gene expression in the wound after perianal abscess surgery. Methods: Patients with perianal abscess who received surgical resection in the Eighth Hospital of Wuhan between May 2014 and February 2017 were selected and randomly divided into the group A who received calcium alginate dressing combined with kangfuxin solution and recombinant human epidermal growth factor for dressing change and the group B who received kangfuxin solution and recombinant human epidermal growth factor for dressing change. 3 d, 6 d and 9 d after dressing change, appropriate amount of wound tissue was collected to determine the expression of cytokines, collagen metabolites and apoptosis genes. Results: 3 d, 6 d and 9 d after dressing change, TGF-β1, Smad3, EGF and bFGF protein expression as well as Col-I, Col-II, Col-III, TIMP1 and TIMP2 protein expression in wounds of both groups of patients were increasing while Fas, FasL, Bax and Caspase-3 protein expression were decreasing, and TGF-β1, Smad3, EGF and bFGF protein expression as well as Col-I, Col-II, Col-III, TIMP1 and TIMP2 protein expression in wounds of group A were significantly higher than those of group B while Fas, FasL, Bax and Caspase-3 protein expression were significantly lower than those of group B. Conclusion: Calcium alginate dressing for wound dressing after perianal abscess surgery an increase the pro-proliferation cytokine expression, adjust the collagen synthesis - degradation balance and inhibit apoptosis, and it is conducive to wound healing.

苹果sMdCAX11基因的功能分析与鉴定

【目的】深入分析苹果sMdCAX11(去掉NRR区域的MdCAX11)基因功能。【方法】分别利用蜜脆苹果果实和拟南芥材料,采用过表达sMdCAX11的试验方法,观察果实、叶片等各组织的表型,并测定不同组织的矿质元素含量,同时对苹果MdCAX11基因启动子区域进行预测分析以及启动子转录活性分析。【结果】瞬时过表达sMdCAX11的苹果果肉颜色变褐,并出现皱缩;同时过表达sMdCAX11的苹果果肉和拟南芥叶片的总Ca含量明显下降,且元素比值(K+Mg)/Ca明显升高。【结论】sMdCAX11基因过表达可导致植株组织的元素分配不均,不同元素间的比例失衡。

Ca-alginate spheres behavior in presence of some solvents and water-solvent mixtures

Immobilization systems more frequently used are calcium alginate spheres. These biocatalysts have many potential applications in the immobilization of enzymes, prokaryotic cells, vegetal and animal cells, algae, organelles and mixtures of these living components. Other applications of immobilized cells imply the use of non aqueous systems. Some bioconversions are carried out in the presence of solvents such as hexane acetone or acetonitrile, or mixtures water-solvents. The aim of this work was to investigate the behaviour of Ca-alginate spheres when put in contact with different solvents (water, diesel, ethanol, methanol, acetone, n-hexane, isopropyl alcohol, THF, acetonitrile, and toluene), or solvent-water mixtures (i.e., ethanol-water), regarding the resistance of the alginate spheres after days of contact. Calcium alginate particles suffered different damages, depending on the solvent they were put in contact. Water did not damaged the Ca-alginate structure with or without Ca present. On the other hand different solvents lost a proportion of volume, i.e., n-hexane (16%), methanol (19%), ethanol (19.5%), toluene (22%), diesel (34%), acetone (765), isopropyl alcohol (80%), THF and acetonitrile (total loss, total destruction). Nor the dielectric constant nor the polarity indexes were capable of explaining the difference on the volume loss or total sphere destruction, except for water-ethanol mixtures.

Swelling Studies and in vitro Release of Acemetacin and BSA from Alginate Gel Beads Crosslinked with Ca^(2+) or Ba^(2+)

The aim of the present work was to investigate the swelling behavior and the in vitro release of acemetacin and bovine serum albumin from alginate gel beads crosslinked with Ca2＋ or Ba2＋. The release profiles suggested that the extent of swelling of the alginate beads played an important role in the release of drug. Small drugs are mainly released via diffusion through the alginate gel matrix. Compared with small drugs, large molecule drugs are difficult to diffuse through the pores of the matrix bead until the beads swell to a certain extent to provide enough large pores. The Ba2＋ crosslinked alginate beads showed slower release rate compared with the Ca2＋ crosslinked alginate beads, whether loaded the large molecules or small drugs. In conclusion, the Ba2＋ crosslinked alginate beads are considered more suitable than Ca2＋ crosslinked alginate beads for using as a sustained release vehicle especially for large molecule drugs.

Effect of Polysaccharide Species on Storage Stability of Alginate Capsules Containing <i>α</i>-Tocopherol

Alginate capsules containing α-tocopherol were prepared adding polysaccharide species such as κ-carrageenan, gellan gum, pectin, curdlan and ghatti gum. The effects of polysaccharide species and the diameters of α-tocopherol on storage stability of the capsules were investigated and characterized in detail. As the contact angle of α-tocopherol to the capsule shell strongly affected storage stability, the contact angle was measured on the model sheet made of calcium alginate with polysaccharide species. The leakage ratio decreased with the contact angle and increased with the diameter of α-tocopherol. The capsules made of calcium alginate with gellan gum showed the largest contact angle and the highest storage stability. The capsules made of calcium alginate with curdlan, ghatti gum and pectin were harder than other capsules and showed higher storage stability. All the capsules showed the almost similar swelling ratio in the acidic solution with pH 4, but showed the different swelling ratios according to the polysaccharide species in the alkali solution with pH 9. The tablets were prepared with the wet and the dried capsules. The tablets prepared with the dried capsules showed higher storage stability.

Micro-environmentally Restricted Yeast Cell Growth within Ca-alginate Microbeads

Micro-environmental restriction effects to yeast cell growth obtained within Ca-alginate microbeads are considered. It is complex phenomenon influenced by: (1) relaxation of expanded polymer network around the cellular clusters, (2) forces generated by cell growth inside the beads and (3) interactions between solvent, network parts and cells. The resulting effects are measured experimentally by estimating volume of microbeads and yeast cell concentration as function of time of cultivation. Comparative analysis of dynamics of cell growth and increase of microbead volume through four regimes indicates that reversible and irreversible local structural changes of Ca-alginate hydrogel induces micro-environmental restrictions to cell growth. The mechanism of restrictions includes both mechanical and electrostatic effects.

Eco-friendly calcium alginate microspheres enable enhanced profile control and oil displacement

Polymer microspheres(PMs),such as polyacrylamide,have been widely applied for enhanced oil recovery(EOR),yet with environmental concerns.Here,we report a microfluid displacement technology containing a bio-based eco-friendly material,i.e.,calcium alginate(CaAlg)microspheres for EOR.Two dominant mechanisms responsible for EOR over Ca Alg fluid have been verified,including the microscopic oil displacement efficacy augmented by regulating capillary force(determined by the joint action of interfacial tension and wettability between different phases)and macroscopic sweep volume increment through profile control and mobility ratio reduction.This comprehensive effectiveness can be further impacted when the CaAlg microsphere is embellished ulteriorly by using appropriate amount of sodium dodecyl sulfonate(SDS).The core flooding and nuclear magnetic resonance(NMR)tests demonstrate that CaAlg-SDS microsphere can balance the interphase property regulation(wettability alteration and IFT reduction)and rheology properties,enabling simultaneous profile control and oil displacement.Excessive introduction of SDS will have a negative impact on rheological properties,which is not favored for EOR.Our results show that the involvement of 4-m M SDS will provide the best behavior,with an EOR rate of 34.38%.This cost-effective and environmentally-friendly bio-microspherebased microfluidic displacement technology is expected to achieve“green”oil recovery in future oilfield exploitation.

水溶液环境下手性配合物Phe·Ca^(2+)对映异构机理的DFT研究

采用DFT(density functional theory)的M06-2X、MN15方法和处理溶剂效应的SMD模型方法,研究了水溶液中S-苯丙氨酸(S-Phe)与二价钙(Ca^(2+))配合物(Phe·Ca^(2+))的对映异构。反应通道研究发现,S-Phe·Ca^(2+)的对映异构可在质子以N和O分别为桥以及O和N联合为桥迁移的3个通道上实现。计算表明:最优势通道是质子以N为桥迁移,隐性水溶剂效应下决速步自由能垒是227.5 kJ/mol,显性水溶剂效应下该能垒降至108.0~117.6 kJ/mol。结果表明:水溶液中手性Phe·Ca^(2+)的消旋过程十分缓慢,将其用于生命体同补苯丙氨酸和钙元素可能比较安全。

Altered expression of stromal interaction molecule(STIM)-calcium release-activated calcium channel protein(ORAI) and inositol1,4,5-trisphosphate receptors(IP_3Rs)in cancer:will they become a new battlefield for oncotherapy?

The stromal interaction molecule(STIM)-calcium release-activated calcium channel protein(ORAI) and inositol1,4,5-trisphosphate receptors(IP_3Rs) play pivotal roles in the modulation of Ca^(2+)-regulated pathways from gene transcription to cell apoptosis by driving calcium-dependent signaling processes.Increasing evidence has implicated the dysregulation of STIM-ORAI and IP_3Rs in tumorigenesis and tumor progression.By controlling the activities,structure,and/or expression levels of these Ca^(2+)-transporting proteins,malignant cancer cells can hijack them to drive essential biological functions for tumor development.However,the molecular mechanisms underlying the participation of STIM-ORAI and IP_3Rs in the biological behavior of cancer remain elusive.In this review,we summarize recent advances regarding STIM-ORAI and IP_3Rs and discuss how they promote cell proliferation,apoptosis evasion,and cell migration through temporal and spatial rearrangements in certain types of malignant cells.An understanding of the essential roles of STIM-ORAI and IP_3Rs may provide new pharmacologic targets that achieve a better therapeutic effect by inhibiting their actions in key intracellular signaling pathways.

Polydatin attenuated food allergy via store-operated calcium channels in mast cell

AIM: To investigate the effect of polydatin (PD), a resveratrol glucoside, on mast cell degranulation and antiallergic activity. METHODS: After the rats were orally sensitized with ovalbumin (OVA) for 48 d and underwent PD treatment for 4 d, all the rats were stimulated by 100 mg/mL OVA for24 h and then sacrificed for the following experiments. The small intestines from all the groups were prepared for morphology examination by hematoxylin and eosin staining. We also used a smooth muscle organ bath to evaluate the motility of the small intestines. The OVA-specific immunoglobulin E (IgE) production and interleu-kin-4 (IL-4) levels in serum or supernatant of intestinal mucosa homogenates were analyzed by enzyme-linked immunosorbent assay (ELISA). Using toluidine blue stain, the activation and degranulation of isolated rat peritoneal mast cells (RPMCs) were analyzed. Release of histamine from RPMCs was measured by ELISA, and regulation of PD on intracellular Ca 2+ mobilization was investigated by probing intracellular Ca 2+ with fluo-4 fluo-rescent dye, with the signal recorded and analyzed. RESULTS: We found that intragastric treatment with PD significantly reduced loss of mucosal barrier integrity in the small intestine. However, OVA-sensitization caused significant hyperactivity in the small intestine of allergic rats, which was attenuated by PD administration by 42% (1.26 ± 0.13 g vs OVA 2.18 ± 0.21 g, P < 0.01). PD therapy also inhibited IgE production (3.95 ± 0.53 ng/mL vs OVA 4.53 ± 0.52 ng/mL, P < 0.05) by suppressing the secretion of Th2-type cytokine, IL-4, by 34% (38.58 ± 4.41 pg/mLvs OVA 58.15 ± 6.24 pg/mL, P < 0.01). The ratio of degranulated mast cells, as indicated by vehicles (at least five) around the cells, dramatically increased in the OVA group by 5.5 fold (63.50% ± 15.51% vs phosphate-buffered saline 11.15% ± 8.26%, P < 0.001) and fell by 65% after PD treatment (21.95% ± 4.37% vs OVA 63.50% ± 15.51%, P < 0.001). PD mediated attenuation of mast cell degranulation was further confirmed by decreased histamine levels in both serum (5.98 ± 0.17 vs OVA 6.67 ± 0.12, P < 0.05) and intestinal mucosa homogenates (5.83 ± 0.91 vs OVA 7.35 ± 0.97, P < 0.05). Furthermore, we demonstrated that administration with PD significantly decreased mast cell degranulation due to reduced Ca 2+ influx through store-operated calcium channels (SOCs) (2.35 ± 0.39vs OVA 3.51 ± 0.38,P < 0.01).CONCLUSION: Taken together, our data indicate that PD stabilizes mast cells by suppressing intracellular Ca 2+ mobilization, mainly through inhibiting Ca 2+ entry via SOCs, thus exerting a protective role against OVA-sensitized food allergy.

Methodological study on endogenous calcium absorptivity using rats and 41Ca tracing

Elemental calcium plays an important role in human physiology. In order to study the relationship between Ca-intake, Ca-chemical formulation, and Ca-absorptivity, a balance experiment using a ^(41)Ca tracer technique in SD rats was conducted to measure the endogenous fecal calcium and true absorption of calcium. Apparent absorption of calcium was measured as a control to the endogenous calcium labeling experiment. These results show that by using ^(41)Ca labeled endogenous calcium in vivo, researchers could obtain the true calcium absorption data without extrinsic labeling. Therefore, the method was not affected by the chemical structure or type of calcium supplement and might be used in evaluating the absorptivity of marketed calcium supplements.