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N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (HTCC) is water-soluble derivative of chitosan (CS), synthesized by the reaction between glycidyl-trimethyl-ammonium chloride and CS. HTCC nanoparticles have been formed based on ionic gelation process of HTCC and sodium tripolyphosphate (TPP). Bovine serum albumin (BSA), as a model protein drug, was incorporated into the HTCC nanoparticles. HTCC nanoparticles were 110-180 nm in size, and their encapsulation efficiency was up to 90%. In vitro release studies showed a burst effect and a slow and continuous release followed. Encapsulation efficiency was obviously increased with increase of initial BSA concentration. Increasing TPP concentration from 0.5 to 0.7 mg/ml promoted encapsulation efficiency from 46.7% to 90%, and delayed release. As for modified HTCC nanoparticles, adding polyethylene glycol (PEG) or sodium alginate obviously decreased the burst effect of BSA from 42% to 18%. Encapsulation efficiency was significantly reduced from 47.6% to 2% with increase of PEG from 1.0 to 20.0 mg/ml. Encapsulation efficiency was increased from 14.5% to 25.4% with increase of alginate from 0.3 to 1.0 mg/ml.

The interactions of hydrophobically modified polyelectrolytes poly(acrylamide–sodium acrylic acid–N-(4-butyl)phenylacrylamide [P(AM-AA-BPAM)] with anionic (sodium dodecyl sulfate), cationic (cetyl trimethylammonium bromide), and nonionic (tetradecyldimethyl-aminoxid) surfactants were studied via solution rheology, surface tension, and atomic force microscopy measurements. Viscosity measurements indicated that the intermolecular association of the polymer was greatly enhanced by the interaction with the surfactants, especially the oppositely charged surfactants with both a hydrophobic association and an electrostatic attraction. The greatest viscosity increase was realized with the addition of such oppositely charged surfactants. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2664–2671, 2003

A new method for the chemical modification of chitosan sulfate was used to prepare N-propanoyl-, N-hexanoyl- and N,O-quaternary substituted chitosan sulfate. Structural analysis by elemental analysis, FTIR, 13C NMR, and 1H NMR spectroscopy, and gel-permeation chromatography showed that these methods could conveniently be used for the introduction of functional groups. The influences of the acyl or quaternary groups on the anticoagulant activity of the polysaccharides were studied with respect to activated partial thromboplastin time (APTT) thrombin time (TT), and prothrombin time (PT). The propanoyl and hexanoyl groups increased the APTT activity, and the propanoyl groups also increased the TT anticoagulant activity slightly, while the N,O-quaternary chitosan sulfate showed only a slight TT coagulant activity.

In this paper six different equations were used to fit the data of dilute solution of both nonionic (PBAM3) and ionic (PBAMS) hydrophobically associating polyacrylamide with and without the addition of NaCl. The results showed that Fedors equation was the most accurate equation to describe the dilute solution properties of these kinds of polymers. The lower value of the polymer concentration parameter ( C m ) in Fedors equation was corresponded to the higher value of the constant k in Schulz–Blaschke equation for PBAM3 system. Two types of polymers had anti-polyelectrolyte effect. In dilute solution the PBAMS polymer chains had a more extended conformation than those of PBAM3 due to the existence of ionic groups.

Copolymers of acrylamide (AM) and N-arylalkylacrylamide (AAM) have been synthesized by free radical micellar copolymerization in aqueous solution utilizing sodium dodecyl sulphate (SDS) as the surfactant and ammonium persulfate/sodium bisulfite as the redox initiator. Some factors affecting synthesis, such as the amount of AAM, SDS and 2-acrylamide-2-methylpropane sulfate, are described. Solution behaviors of these polymers were studied. The results show that with the increase of AAM content, the intrinsic viscosity decreases, Huggins constant increases and the viscosification effect increase. The addition of NaCl and CaCl2 results an increase of solution viscosity, and the addition of surfactant has a significant and complex effect to solution viscosities. The polymers exhibit good temperature tolerance property, shear-thickening and thixotropy behavior.

The gelation of metallic crosslinking agent titanium(IV) (Ti(IV)) with partially hydrolyzed polyacrylamide (HPAM) is reported. Factors affecting the crosslinking reaction are discussed and the dynamic properties of the gel are examined. The results indicate that crosslinking of Ti(IV) with HPAM is delayed at low concentrations of polymer and titanium tartrate. The gelling of Ti(IV)–HPAM is a strong function of titanium/tartaric acid molar ratios, HPAM concentration, initial solution pH value, solution salinity, and the hydrolysis degree of HPAM. The gel strength depends on Ti(IV) concentration in a particular way; after a maximum Ti(IV) concentration is reached gel strength decreases. The salt NaCl can accelerate the gelling rate of Ti(IV)–HPAM. A crosslinking mechanism of Ti(IV) with HPAM is proposed. Ti(IV)–HPAM gel can hold its strength at moderate temperature (50°C) for a long time making it suitable to be used in a moderate temperature oil reservoir.

The gelation of metallic crosslinking agent titanium(IV) (Ti(IV)) with partially hydrolyzed polyacrylamide (HPAM) is studied. Factors effecting the crosslinking reaction are discussed and the dynamic properties of gel are examined. The results indicate that crosslinking of Ti(IV) with HPAM is delayed at low concentrations of polymer and the titanium tartrate. The gelling of Ti(IV)–HPAM is a strong function of titanium/tartaric acid molar ratio, HPAM concentration, initial solution pH value, solution salinity, and hydrolysis degree of HPAM. The gel strength depends on Ti(IV) concentration in a particular way, after a maximum Ti(IV) concentration is reached gel strength decreases. The salt NaCl can accelerate the gelling rate of Ti(IV)-HPAM. The crosslinking mechanism of Ti(IV) with HPAM is proposed. Ti(IV)-HPAM gel can hold its strength at moderate temperature (50°C) for a long time which is suitable to be used in a moderate temperature oil reservoir.

Chitosan and poly(vinyl alcohol) blend fibers were prepared by spinning their solution through a viscose-type spinneret at 25°C into a coagulating bath containing aqueous NaOH and ethanol. The influence of coagulation solution composition on the spinning performance was discussed, and the intermolecular interactions of blend fibers were studied by infrared analysis (IR), X-ray diffraction (XRD), and scanning electron micrograph (SEM) and by measurements of mechanical properties and water-retention properties. The results demonstrated that the water-retention properties and mechanical properties of the blend fibers increase due to the presence of PVA in the chitosan substract, and the mechanical strength of the blends is also related to PVA content and the degree of deacetylation of chitosan. The best mechanical strength values of the blend fibers, 1.82 cN/d (dry state) and 0.81 cN/d (wet state), were obtained when PVA content was 20 wt % and the degree of deacetylation of chitosan was 90.2%. The strength of the blend fibers, especially wet tenacity could be improved further by crosslinking with glutaraldehyde. The water-retention values (WRV) of the blend fibers were between 170 and 241%, obviously higher than pure chitosan fiber (120%). The structure analysis indicated that there are strong interaction and good miscibility between chitosan and poly(vinyl alcohol) molecular resulted from intermolecular hydrogen bonds. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2558–2565, 2001

Ethanol direct injection plus gasoline port injection (EDI+GPI) is a new technology to make the use of ethanol fuel more effective and efficient in spark ignition engines. It takes the advantages of ethanol fuel, such as its greater latent heat of vaporization than that of gasoline fuel, to enhance the charge cooling effect and consequently to increase the compression ratio and improve the engine thermal efficiency. Experimental investigation has shown improvement in the performance of a single cylinder spark ignition engine equipped with EDI+GPI. It was inferred that the charge cooling enhanced by EDI played an important role. To investigate it, a CFD model has been developed for the experimentally tested engine. The Eulerian-Lagrangian approach and Discrete Droplet Model were used to model the evolution of the fuel sprays. The model was verified by comparing the numerical and experimental results of cylinder pressure during the intake and compression strokes. Mesh density and time step sensitivities have been tested. The verified model was used to investigate the charge cooling effect of EDI in terms of spatial and temporal distributions of cylinder temperature and fuel vapor fraction. Compared with GPI only, EDI+GPI demonstrated stronger effect on charge cooling by decreased in-cylinder temperature. The cooling effect was limited by the low evaporation rate of the ethanol fuel due to its lower saturation vapor pressure than gasoline's in low temperature conditions. Copyright © 2013 SAE International and Copyright © 2013 KSAE.

Effects of fuel and ambient gas temperature on the spray and combustion characteristics of soybean biodiesel were studied in a constant-volume combustion chamber. Four different fuels or fuel blends including B0, B20, B50 and B100 were investigated experimentally. The soot mass data were obtained via a new technique called forward illumination light extinction (FILE). The ambient gas temperature was varied from 700 K to 1200 K. To simulate the engine operating conditions, the ambient oxygen concentration and its density were kept at 21 % and 15 kg/m3, respectively. A higher peak pressure is found as the biodiesel content decreases. B20, B50 and B100 have a shorter ignition delay than B0 and the ignition delay decreases with increasing biodiesel content. The liquid penetration decreases with decreasing biodiesel content. Moreover, the integrated natural flame luminosity (INFL) increases with decreasing biodiesel content. Shorter flame (i.e., soot luminosity) duration and a longer delay between start of combustion (SOC) and the appearance of flame are found as the biodiesel content increases. The flame duration also increases with increasing ambient gas temperature for all fuels. Soot is lower and appears later at a lower ambient gas temperature, while it is burned out at around the same time. Near-zero soot mass was observed for all tested fuels at 700 K. A shorter soot formation process is observed for biodiesel fuels. The soot reduction using B20 and B50 is not obvious compared to B0 at a low temperature. But under the ordinary diesel engine operating condition at 1000 K, the soot reduction is significant. It is also found that the soot can be reduced by 60% and above when B100 is used in this study.

A total of 229 genotypes of 20 Amaranthus species from the United States Department of Agriculture – Agricultural Research Service (USDA – ARS) National Plant Germplasm Amaranth Collection was evaluated in field experiments in Beijing and Wuhan, China, in 1994. Agronomic traits, including plant height, maturity, leaf number and color, stem color, seed color, branch number, 1000-grain-weight, yield per plant, and resistance to stresses (including diseases) were measured. The results indicated: 1. Many of the species were sensitive to daylength; 2. Cultivated genotypes generally had higher grain yield but were more seriously affected by diseases than non-cultivated species; 3. There was wide diversity in agronomic traits among Amaranthus species and among genotypes within the same species, and several genotypes were identified that appeared to carry favorable agronomic traits of immediate use in cultivar improvement; 4. For introduction of genotypes for use in plant breeding in China, selection should be partially based on matching the climates of the location of origin and the target area for production.

A new kind of hydrophobically associating water-soluble terpolymer P(AM-NVP-DMDA) was synthesized by free radical terpolymerization. Compared with micellar terpolymerization, this terpolymerization can be conducted in aqueous solution in absence of external surfactant, because the hydrophobic monomer is surface active. Synthesis, structure, and solution properties of P(AM-NVP-DMDA) terpolymer were studied, including its electrolyte effect, rheological behavior, temperature dependence of viscosity, dilute solution property, and the polymer-alkali, polymer-surfactant interaction. The terpolymer shows strong hydrophobic effect, and the terpolymer aqueous brine solution exhibits high viscosity at low polymer concentration. Incorporation of N-vinyl-pyrrolidone into the terpolymer causes an improvement in thermal stability of the terpolymer. The transmission electron photomicrograph analysis of the terpolymer indicates that the presence of the microphase separation of the terpolymer in aqueous solution plays an important role in the viscosification efficiency of the terpolymer.

The betacyanin pigments from 21 genotypes of 7 Amaranthus species were separated by gel filtration chromatography and HPLC. On the basis of their IR and UV−visible spectra, enzymatic hydrolysis, and chromatographic profiles, the pigments were identified as homogeneous betacyanins, which consisted on average of 80.9% amaranthine and 19.2% isoamaranthine. Dried crude betacyanin extracts contained 23.2−31.7% protein, and the purified sample retained 12.8% protein. The betacyanins were difficult to separate from protein. Total betacyanins in the Amaranthus species ranged from 46.1 to 199 mg/100 g of fresh plant material and from 15.4 to 46.9 mg/g of dry extracts. The mean extraction rate of the eight best genotypes was 2.18%. Amaranthus cultivated species contained much more betacyanin than wild species and had much higher biomass, indicating that certain cultivated genotypes had greater potential for commercial development as natural colorant sources. Dried extracts from Amaranthus species may form natural n...

The spray structure and its developments generated by a multi-hole gasoline direct injection (GDI) have been investigated and discussed. Experiments were carried out on a constant volume chamber (CVC) rig. The effects of injection pressure, ambient pressure and ambient temperature were examined using high speed CCD camera. Images were processed by a specific program based on MatLAB. The spray tip penetration and overall spray cone angle were then analyzed and discussed. It was found that the spray penetration was mostly affected by ambient pressure and by injection secondly, while the ambient temperature slightly affected them both.

Thermal balance of the LNG (liquefied natural gas) engine were tested on overall conditions at four different coolant temperatures, which were set at 60°C, 70°C, 80°C and 90°C in the tests. The testing results show that coolant temperatures have influence on the heat distribution of the LNG engine. As coolant temperature climbs, proportion of useful power increases and less proportion of heat are taken away by coolant, resulting better fuel economy but more NOx emission. The coolant temperature influences HC and CO emissions, although in unobvious ways.

At present, in the simulation of working process in engine, the trial-and-error method are often used to set the ignition advance angle, air fuel ratio and so on. It would take much time and need rich experience by using the trial-and-error method. In this paper, an optimized simulation method based on performance target control is proposed. By the method, the performance goal of torque was set as the optimization objective, and the ignition advance angle, air fuel ratio and some other parameters were set as control variables in control sub-modules of the simulation model. Then in the simulation, those control variables were adopted in a certain range automatically by PID to optimize the engine performance such as power, BSFC, in guarantees the knock and exhaust temperature under the limiting value. The method has great application to forecast and optimize the performance of new gasoline engine in the concept design. By the method, performance of one turbocharged MPI gasoline engine is optimized. At first, on the basis of experiment result, the working process numerical model of the same series naturally aspirated gasoline engine model was calibrated. Secondly, with the calibrated model, working process numerical model of the turbocharged MPI gasoline engine is established based on target control method. In succeed, turbochargers were matched, compression ratio, intake and exhaust manifold structure, cam lift and valve timing were optimized, thus made the whole performance of the engine better.

The temperature measurement device was developed. After its error was calibrated, the system has an accuracy of ± 1 °. The reliability of the device was high. In this paper, authors measured the piston temperature when the CNG engine was at maximum value of the torque, the oil/water temperature steady.

To solve problems such as thermal overload in the cylinder head of a 6-cylinder heavy-duty diesel engine and the thermal cracks in the valve-bridge of the engine. Structure of the coolant jacket was optimized from monolayer to bi-layer, and structures of upper nozzles were also optimized using the orthogonal experimental design method in this paper. At present, the cooling capacity of the coolant jacket in cylinder head is mainly judged by the coolant velocity. In this paper, the coolant heat transfer coefficient (HTC) was adopted as the criterion to evaluate the heat transfer process in cylinder head. Both of the velocity and HTC were used as the evaluation indexes to obtain the optimum schemes respectively. To determine which evaluation index fits the actual heat transfer process better, and which optimized schemes should be adopted, the temperatures in the bottom of the cylinder head were measured. The experimental results show that it is better to evaluate the cooling capacity of coolant jackets by HTC. HTC reflects the actual heat transfer process much better than velocity.Copyright © 2010 by ASME

With the debut of a new class of multi-port ATE (e.g., Agilent 93000 series), there is a pressing need for test planning methods to fully adapting SoC test framework design to the new concurrent test capabilities and fulfil emerging demands of high-speed testing. In this paper, we propose a new test planning strategy that addresses multi-frequency SoC testing by dynamically reconfiguring ATE ports. The system integrators on-the-fly group pins into virtual ports while ATE ports simultaneously drive the testing of a set of cores at multiple independent clock domains. An effective and efficient system optimization technique is developed to manage test resources and improve test efficiency for modern complex SoC designs.

The paper has explored the solutions to the thermal overload in the cylinder head of a heavy-duty vehicle 6-cylinder diesel engine and the thermal cracks in the valve-bridge of the engine. The experiments include measuring the temperature of the cylinder head bottom and testing the flow distribution of coolant through the upper nozzles of cylinder head bottom. The follow-up analysis was conducted on the causes of the excessive thermal load of the cylinder head bottom, the thermal cracks in the valve-bridge region, and the rationality of the structure of the water jacket for the cylinder head. The mechanism of the water jacket of cylinder head was further inquired. Then 3-D CFD numerical simulation of water jacket in the sixth cylinder, which is in the worst cooling condition, is performed. To enhance the flow form in water jacket and lower the cost of enhancement, we proposed 4 schemes of water jacket and conducted the numerical simulations to these schemes. It was identified that all these schemes have efficiently improved the flow field in water jacket. In the typical proposed scheme 1 in which 6 nozzles of all the 10 upper nozzles were blocked, the coolant flow rate on the bottom of the water jacket and in the cylinder head valve-bridge region increased by about 68.73%. The measuring results of the cylinder head bottom temperature show that the maximum temperature in the valve-bridge region of cylinder head is reduced by 9.2 °C and the temperature gradient reduction is 19.55 percent, suggesting that the thermal load and thermal stress of the studied diesel engine cylinder head has been significantly lowered.Copyright © 2007 by ASME

Studying the vaporizing characteristics of diesel spray could greatly help to reduce engine emission and improve performance. The high-speed schlieren imaging method is an important optical technique for investigating the macroscopic vaporizing morphological evolution of liquid fuel, and pre-combustion constant volume combustion bombs are often used to simulate the high pressure and high temperature conditions occurring in diesel engines. Complicated background schlieren noises make it difficult to segment the spray region in schlieren spray images. To tackle this problem, this paper develops a vaporizing spray boundary segmentation methodology based on an automatic threshold determination algorithm. The methodology was also used to quantify the macroscopic characteristics of vaporizing sprays including tip penetration, near-field and far-field angles, and projected spray area and spray volume. The spray boundary segmentation methodology was realized in a MATLAB-based program. Comparisons were made between the spray characteristics obtained using the program method and those acquired using a manual method and the Hiroyasu prediction model. It is demonstrated that the methodology can segment and measure vaporizing sprays precisely and efficiently. Furthermore, the experimental results show that the spray angles were slightly affected by the injection pressure at high temperature and high pressure and under inert conditions. A higher injection pressure leads to longer spray tip penetration and a larger projected area and volume, while elevating the temperature of the environment can significantly promote the evaporation of cold fuel.

Even though several studies report the importance of chitosan derivatives for their anticancer activity, no clear information is available to describe the relationship between their charge properties and observed activities. In this research, differently charged chitooligosaccharide (COS) derivatives were synthesized and their anticancer activities were studied using three cancer cell lines, HeLa, Hep3B and SW480. Neutral red and MTT cell viability studies revealed that, highly charged COS derivatives could significantly reduce cancer cell viability, regardless to the positive or negative charge. Further, fluorescence microscopic observations and DNA fragmentation studies confirmed that the anticancer effect of these highly charged COS derivatives were due to necrosis. However, the exact molecular mechanism for anticancer activity of strongly charged COS compared to their poorly charged counterparts is not clear.

Scavenging activity of hydroxyethyl chitosan sulfate (HCS) against 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl and carbon-centered radical species were studied using electron spin resonance (ESR) spectroscopy. In addition, its antioxidant activity to retard lipid peroxidation was also evaluated in a linoleic acid model system. HCS could scavenge DPPH (33.78%, 2.5 mg/mL) and carbon-centered radicals (67.74%, 0.25 mg/mL) effectively. However, chitosan sulfate did not exhibit any scavenging activity against hydroxyl radicals, but increased its generation. This was different from the published literature and was presumed due to the loss of chelating ability on Fe2+. This assumption could further confirm from the results obtained for Fe2+-ferrozine method that upon sulfation chitooligosaccharides lost its chelation properties. Therefore, HCS can be identified as antioxidant that effectively scavenges carbon centered radicals to retard lipid peroxidation.

A natural lacquer polysaccharide with complex branches was separated into two fractions, LPH (MW 16.9x10(4)) and LPL (MW 6.85x10(4)). Results of 13C NMR and FT-IR indicated they had the same structure. The treatment of LPL with sodium periodate led to a partial cut-off of side chains with 4-O-methyl-D-glucuronic acid in the terminal. These polysaccharides were sulfated in the presence of Py*SO3/DMSO. Depending on the reaction conditions, the products showed a different degree of sulfation (DS) ranging from 0.57 to 1.57 and different molecular weights ranging from 1.71x10(4) to 3.49x10(4). FT-IR analysis showed the equatorial primary OH at O-6 and the axial secondary OH at O-4 were sulfated. Activated partial thromboplastin time (APTT), prothrombin time and thrombin time (TT) assays showed the sulfated polysaccharides could prolong APTT and TT, but not TP. These activities strongly depended on the DS, the molecular weights (MW) and the branching structure of polysaccharides. DS of above 0.8 was essential for anticoagulant activity. The anticoagulant activity increased with the DS and the molecular weights. The molecular weights played a more important role. The branching structure of polysaccharides increased the activities. In our studies, the sulfated polysaccharides with the DS of 1.15 and the highest MW of 3.49x10(4) had the best blood anticoagulant activities.