Ice formation on solid surfaces is an important phenomenon in many fields, such as cloud formation and atmospheric icing, and a key factor for applications in preventing freezing. Here, we report temperature-dependent nucleation rates of ice for hydrophilic and hydrophobic surfaces. The results show that hydrophilic surface presents a lower ice nucleation rate. We develop a strategy to extract the thermodynamic parameters, J0 and Γ, in the context of classical nucleation theory. From the extracted J0 and Γ, we reveal the dominant role played by interfacial water. The results provide an insight into freezing mechanism on solid surfaces.

In this paper, an anti-icing coating with an aqueous lubricating layer is reported. This anti-icing coating can be directly applied to various substrates, and the ice adhesion strength on the coated surfaces can be lowered greatly as compared to uncoated substrates. We demonstrate for the first time that the formed ice on this anti-icing coating can be blown off by a wind action in the wind tunnel with a controlled temperature and wind velocity. Moreover, the low ice adhesion of the anti-icing coating can be maintained even when the temperature is lowered to -53 °C. The robustness and durability of the anti-icing coating are proved by the icing/de-icing experiments. The results show that the anti-icing coating with an aqueous lubricating layer is of great promise for practical applications.

Superhydrophobic porous surfaces with hydrophilic polymers adsorbed in pores are designed to control the coalescing behavior of microdroplets as well as their quick self-removal. The combination of chemical composition and surface structure are greatly important in the design of new materials for heat exchange, antifogging, and anti-icing.

A robust prototypical anti-icing coating with a self-lubricating liquid water layer (SLWL) is fabricated via grafting cross-linked hygroscopic polymers inside the micropores of silicon wafer surfaces. The ice adhesion on the surface with SLWL is 1 order of magnitude lower than that on the superhydrophobic surfaces and the ice formed atop of it can be blown off by an action of strong breeze. The surface with self-lubricating liquid water layer exhibits excellent capability of self-healing and abrasion resistance. The SLWL surface should also find applications in antifogging and self-cleaning by rainfall, in addition to anti-icing and antifrosting.

A novel substance, cationic acetylcholine potato starch (CAPS), was developed for the first time. The synthesis process had three steps: first, carboxymethyl potato starch (CMPS) was synthesized under sodium hydroxide alkaline condition and in isopropyl alcohol organic media; second, bromocholine chloride (BCC) was synthesized with sulphuric acid as a catalytic agent; finally, CAPS was synthesized by the reaction of CMPS with BCC in N,N'-dimethylformamide (DMF). The degree of substitution (DS) of CAPS was determined by ammonia gas-sensing electrode and elemental analysis. CAPS was characterized by Fourier transformed infrared (FTIR) and near infrared (FTNIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC).

T cell-dependent B-cell responses decline with age, suggesting defective CD4 T-cell function. CD4 memory T cells from individuals older than 65 y displayed increased and sustained transcription of the dual-specific phosphatase 4 (DUSP4) that shortened expression of CD40-ligand (CD40L) and inducible T-cell costimulator (ICOS) (both P < 0.001) and decreased production of IL-4, IL-17A, and IL-21 (all P < 0.001) after in vitro activation. In vivo after influenza vaccination, activated CD4 T cells from elderly individuals had increased DUSP4 transcription (P = 0.002), which inversely correlated with the expression of CD40L (r = 0.65, P = 0.002), ICOS (r = 0.57, P = 0.008), and IL-4 (r = 0.66, P = 0.001). In CD4 KO mice reconstituted with DUSP4 OT-II T cells, DUSP4 had a negative effect on the expansion of antigen-specific B cells (P = 0.003) and the production of ova-specific antibodies (P = 0.03) after immunization. Silencing of DUSP4 in memory CD4 T cells improved CD40L (P < 0.001), IL-4 (P = 0.007), and IL-21 (P = 0.04) expression significantly more in the elderly than young adults. Consequently, the ability of CD4 memory T cells to support B-cell differentiation that was impaired in the elderly (P = 0.004) was restored. Our data suggest that increased DUSP4 expression in activated T cells in the elderly in part accounts for defective adaptive immune responses.

Understanding the mechanism of ice adhesion on surfaces is crucial for anti-icing surfaces, and it is not clear if superhydrophobic surfaces could reduce ice adhesion. Here, we investigate ice adhesion on model surfaces with different wettabilities. The results show that the superhydrophobic surface cannot reduce the ice adhesion, and the ice adhesion strength on the superhydrophilic surface and the superhydrophobic one is almost the same. This can be rationalized by the mechanical interlocking between the ice and the surface texture. Moreover, we find that the ice adhesion strength increases linearly with the area fraction of air in contact with liquid.

A series of surfaces with the similar morphology but different surface free energy were fabricated to achieve surfaces with distinct condensation modes. It was found that the freezing of condensed water formed via filmwise condensation occurred much more quickly and at a higher temperature than that of condensed water formed via dropwise condensation.

Hierarchically structured porous aluminum surfaces for the high efficient removal of condensed water microdroplets are prepared via simply immersing aluminum sheets in hot water followed by modification with a low surface energy chemical. A correlation between the work of adhesion with the self-removal of condensed water microdroplets is established.

Potato starch sulphate (PSS) was synthesized by the reaction between potato starch and sulphuric acid in ethanol. In order to obtain the products with high degree of substitution (DS), the reaction conditions which could influence the DS were optimized, including m(St)/VH2SO4, V-EtOH/VH2SO4, water content in the reaction medium, the reaction temperature and reaction time in sulphation. In this process, the DS of each PSS sample was determined by barium sulphate-glutin nephelometery method. By investigating the relationship between these conditions and DS, the optimal conditions could be obtained with the maximum DS. Besides, the physical properties and chemical structure of PSS were studied, containing solubility, swelling power, FTIR spectra, XRD patterns, gelatinization temperatures and enthalpy measurements.

This study was carried out to develop a new type of modified starch based on α-amylase and glucoamylase. The structural and chemical characteristics of the porous starch were determined by Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The potential application of the porous starch as an adsorbent was evaluated using methyl violet as an adsorbed model. The adsorption capacity was optimized by investigating the reaction factors, including the mass ratio of α-amylase to glucoamylase (mα-amylase/mglucoamylase), the mass ratio of total amount of enzymes to starch (menzyme/mSt), the ratio of liquid volume to starch mass (VH2O/mSt), pH value of the reaction solution, enzymatic reaction temperature, and enzymatic reaction time. The hydrolysis ratio of each sample was also determined to investigate the effect of different reaction conditions on the hydrolysis degree. The results suggest that the porous starch has a more excellent adsorption capacity than the native starch, and may be expected to have wide potential applications in many fields.

The aim of this study was to prepare oxidized guar gum with a simple dry method, basing on guar gum, hydrogen peroxide and a small amount of solvent. To obtain a product with suitable viscosity for reactive dye printing, the effects of various factors such as the amount of oxidant and solvent, reaction temperature and time were studied with respect to the viscosity of reaction products. The product was characterized by Fourier transform infrared spectroscopy, size exclusion chromatography, scanning electron microscopy and differential scanning calorimetry. The hydrated rate of guar gum and oxidized guar gum was estimated through measuring the required time when their solutions (1%, w/v) reached the maximum viscosity. The effects of the salt concentration and pH on viscosity of the resultant product were studied. The mixed paste containing oxidized guar gum and carboxymethyl starch was prepared and its viscosity was determined by the viscometer. The rheological property of the mixed paste was appraised by the printing viscosity index. In addition, the applied effect of mixed paste in reactive dye printing was examined by assessing the fabric stiffness, color yield and sharp edge to the printed image in comparison with sodium alginate. And the results indicated that the mixed paste could partially replace sodium alginate as thickener in reactive dye printing. The study also showed that the method was low cost and eco-friendly and the product would have an extensive application in reactive dye printing.

Novel drug-loaded hydrogel beads for intestine-targeted controlled release were developed by using pH- and temperature-sensitive carboxymethyl chitosan-graft-poly(N,N-diethylacrylamide) (CMCTS-g-PDEA) hydrogel as carriers and vitamin B-2 (VB2) as a model drug. The hydrogel beads were prepared based on Ca2+ ionic crosslinking in acidic solution and formed dual crosslinked network structure. The structure of hydrogel and morphology of drug-loaded beads were characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The study about swelling characteristics of hydrogel beads indicated that the beads had obvious pH- and temperature-sensitivity. In vitro release studies of drug-loaded beads were carried out in pH 1.2 HCl buffer solution and pH 7.4 phosphate buffer solution at 37 degrees C, respectively. The results indicated that the dual crosslinked method could effectively control the drug release rate under gastrointestinal tract (GIT) conditions, which was superior to traditional single crosslinked beads. In addition, the effects of grafting percentage, pH value, and temperature on the release behavior of the VB2 were investigated. The drug release mechanism of CMCTS-g-PDEA drug-loaded beads was analyzed by Peppa's potential equation. According to this study, the dual crosslinked hydrogel beads based on CMCTS-g-PDEA could serve as suitable candidate for drug site-specific carrier in intestine. Copyright (C) 2009 John Wiley & Sons, Ltd.

In this work, a series of hydrogels were prepared by copolymerization of (2-dimethylamino) ethyl methacrylate (DMAEMA) and 3-acrylamidephenylboronic acid (AAPBA). The structure of the resultant hydrogels was studied by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The experimental results from swelling studies revealed that the hydrogels displayed definite glucose sensitivity under physiological conditions, as well as sharp changes in the mesh size of their network as a function of the pH and temperature of the swelling media. Bovine serum albumin (BSA) was selected as a model compound when examining protein release from hydrogels. The results suggested that the temperature, pH and glucose concentration of buffer solutions greatly influenced release profiles.

In this work, the carboxymethyl chitosan (CMCTS) grafted poly(N-vinylpyrrolidone) (PVP) copolymers were synthesized. The hydrogel beads containing VB2 were prepared from the copolymers by an ionic crosslinked. The experimental results shown that VB2 drug release rate from those beads decreased with the increasing grafting percentage, crosslinker concentration and pH value of the medium. Besides, the beads have the better control ability for releasing of model drug than CMCTS does.

A simple method has been developed to prepare smart P(N,N-diethylacrylamide-co-methacrylic acid) (P(DEA-co-MAA)) microspheres that consist of well-defined temperature-sensitive cores and pH sensitive shells. The microgels have been prepared by surfactant-free emulsion polymerization using water as the solvent. The core–shell hydrogel microspheres have been characterized by Fourier transform infrared (FTIR) spectroscopy, UV spectrometry, dynamic light scattering (DLS) and transmission electron micrograph (TEM). Preliminary characterization of the biocompatibility of hydrogel microspheres has been done by the cytotoxicity assays using the HeLa human breast cancer cell line as probes. The in vitro drug release indicates that drug release rate, encapsulation efficiency (EE) and release kinetics depend upon the pH value and copolymer composition. According to this study, the hydrogel microspheres based on P(DEA-co-MAA) could serve as suitable candidate for drug site-specific carrier in intestine.

To optimize the preparation conditions of carboxymethyl potato starch (CMPS), the effects of relevant factors on viscosity (eta) of 2% CMPS aqueous solution and degree Of substitution (DS) were investigated. These condition parameters included etherification temperature, alkalization and etherification time, water content in the mixed solvent, ratio of liquid volume to starch mass, molar ratio Of sodium hydroxide to monochloroacetic acid, and molar ratio of monochloroacetic acid to anhydroglucose unit. After individual parameter influencing eta and DS was researched one by one, an Orthogonal experiment of L-18 (2 x 37) was designed to identify the main factors affecting them. In light of range analysis, the comparative importance of factors impacting eta and DS was obtained, separately. Results of variance analysis showed that the most effective factor to control DS vas etherification temperature, whereas the influences of all factors on eta were not significant. Meanwhile, eta and DS of the optimized final product were found to be 12,000 mPa.s and 0.68, respectively. In addition, the Structure of CMPS was characterized by Fourier transfom-1 infrared (FTIR) spectrophotometer. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 24-33, 2009

Carboxymethyl potato starch (CMPS) was synthesized under heterogeneous reaction conditions. The influences of etherification temperature, alkalization and etherification time, sodium hydroxide to monochloroacetic acid (MCA) molar ratio (nNaOH/nMCA), theoretical degree of substitution (DSt), the ratio of isopropyl alcohol (IPA) volume to starch mass (vIPA/mst) on degree of substitution (DS) and reaction efficiency (RE) of CMPS were investigated. Compared with the previous literature data, the results had significant difference for the optimal carboxymethylation conditions of potato starch from different sources. CMPS prepared under optimal conditions showed the highest DS and RE, which were 1.36 and 0.88, respectively. Furthermore, the RE value in this work is considerably higher than that reported in the literature. The time of alkalization and etherification were also discussed independently. In addition, CMPS was characterized by Fourier transform infrared spectrophotometry and scanning electron microscopy (SEM). Copyright © 2008 John Wiley & Sons, Ltd.

The ability to mount adaptive immune responses to vaccinations and viral infections declines with increasing age. To identify mechanisms leading to immunosenescence, primary CD4 T cell responses were examined in 60- to 75-year-old individuals lacking overt functional defects. Transcriptome analysis indicated a selective defect in zinc homeostasis. CD4 T cell activation was associated with zinc influx via the zinc transporter Zip6, leading to increased free cytoplasmic zinc and activation of negative feedback loops, including the induction of zinc-binding metallothioneins. In young adults, activation-induced cytoplasmic zinc concentrations declined after 2 days to below prestimulation levels. In contrast, activated naïve CD4 T cells from older individuals failed to downregulate cytoplasmic zinc, resulting in excessive induction of metallothioneins. Activation-induced metallothioneins regulated the redox state in activated T cells and accounted for an increased proliferation of old CD4 T cells, suggesting that regulation of T cell zinc homeostasis functions as a compensatory mechanism to preserve the replicative potential of naïve CD4 T cells with age.