2nd-acetone-solubles were analyzed by TGA, CHNS elemental analysis, thermomechanical analysis (TMA) and GPC. Fig. 8 shows the pyrolysis profiles of samples analyzed by TGA. All the profiles were very similar to that of organosolv lignin. 2nd-acetone-solubles of cedar and rice straw decreased the yields of char closer to that of organosolv AG 1879 by the 2nd treatment comparing with those of 1st-acetone-solubles, which meant acetone-solubles were converted into lignin-purer components by the 2nd treatment. 2nd-acetone-soluble of beech lowered its decomposition temperature. Among the main components of biomass, hemicellulose shows the lowest decomposition temperature (about 180 °C) and lignin shows the highest decomposition temperature (about 280 °C), which confirms the assumption discussed in the previous section that some of 1st-water-solubles (hemicellulose derivatives) of beech were converted into acetone-soluble components by the 2nd treatment. The elemental compositions of samples were analyzed by CHNS elemental analysis, and the results are shown in Table 2. All the samples increased carbon contents and decreased oxygen contents from 1st-acetone-solubles. Oxygen content is generally estimated to increase by hydrolysis, however, the carbonation at high temperature had a bigger effect in this reaction. About ash, all the samples contained none of that anymore after the 2nd treatment. Next, the softening temperatures of samples were measured by TMA. The results are listed in Table 4. The softening temperatures of 1st-acetone-solubles of all samples were very different, and high in order from cedar, beech, to rice straw. This difference was because of the difference in constituents of lignin, and the hemicellulose derivative in 1st-acetone-solubles. All the samples lowered the softening temperatures remarkably by the 2nd treatment, which indicated that extracted lignin was depolymerized well. To confirm this, the MWDs of 2nd-acetone-solubles were analyzed by GPC. The results are shown in Fig. 9 with those of 1st-acetone-solubles. The black solid lines and the gray broken lines are, respectively, for 2nd-acetone-solubles and 1st-acetone-solubles. The base lines were shifted for each type of biomass sample. For the relative evaluation by the intensity, 10 mg of each acetone-soluble was dissolved in 5 mL of acetone before the analysis. All the samples increased the intensity of the lower molecular weight fractions of Mw < 1000 by the 2nd treatment. The peaks of the fractions of Mw > 1000 of 1st-acetone-solubles of cedar and rice straw were shifted to lower molecular weight area. 1st-acetone-soluble of beech, different from the other samples, did not have peaks of the higher molecular weight fraction. This was probably because acetone-soluble was actually obtained as “water-insoluble components” in this experimental method, and 1st-acetone-soluble of beech could not be completely dissolved in acetone before the analysis by GPC. Some insoluble fractions were actually recognized in the solution of 1st-acetone-soluble of beech, which supported this assumption. Those insoluble fractions were depolymerized by the 2nd treatment and, converted into acetone-soluble components. As a summary, the acetone-soluble components of all the types of biomass were converted into depolymerized lignin of Mw < 1000 fractions by the 2nd treatment.
2. Modeling and simulation
2.1. KMC simulation of ethylene/1-hexene coordination copolymerization
Generally, when the reaction scheme consists of N ABT-737 elementary reaction channels, the mth reaction can be selected in a given time interval from uniformly distributed random numbers in a unit interval, according to the following relationships:equation(1)∑i=1m-1Pi?r1<∑i=1mPidt=1∑i=1NRiln1r2where r1 and r2 are two random numbers, Pi and Ri are the reaction rate probability and rate of reaction i, respectively, and dt is the time interval between two successive reactions.
In the present study, Gillespie’s algorithm was hybridized with classical statistical copolymerization equations to precisely determine the optimal feeding policy to attempt synthesizing ethylene/1-hexene copolymer chains with predetermined molecular architecture ,  and .
To produce copolymer chains, semibatch coordination copolymerization process of ethylene (monomer E) and 1-hexene (comonomer or monomer H) was simulated. The KMC-based algorithm was constructed on the basis of the reaction scheme and copolymerization conditions suggested by Zhang et al. . In this copolymerization process, according to the proposed mechanism ( Scheme 1), the microstructural characteristics of the final product are significantly controlled by the activation of Et(Ind)2ZrCl2 catalyst, initiation of living chains, propagation of growing chains, chain transfer to 1-hexene, hydrogen abstraction, and the catalyst deactivation. Drawing on the fact that the KMC simulation approach is capable of analyzing and reporting all instantaneous and cumulative microstructural variations during the copolymerization of ethylene/1-hexene, the proposed reaction channel is expected to visualize a more comprehensive and reliable image of the process.
The final process disturbance examined was alkalization condition. NaOH was added using the pH pump to increase the pH to 12.6 for 14 h. This process upset caused a huge difference in the production performance as the HPR decreased to only 0.7 L/L-d; however, the recovery of the process was completed in the next 4 days, reaching the original performance of 10.8 L/L-d. The biohydrogen content recorded the lowest level of 8% at the initial period, and subsequently recovered to 50% after 4 days. The γ-Secretase inhibitor IX concentration peaked to 9 g VSS/L, which could be explained as the alkali nature of the reactor causing detachment of the biofilm attached to the walls of the reactor, thus increased the VSS concentration to the high levels noted. The effluent pH dropped back to normal at 5.6 within 4 days of recovery. Interestingly, very slight changes in the VFA concentrations and proportions were noted, as less than 30% difference in the proportion of acetic acid and butyric acid was observed. The sugar utilization rate was nearly 100% during the process disturbance and recovery period.
Fig. 10. Uncoupled constitutive relationships : (a) normal direction, (b) tangential direction.Figure optionsDownload full-size imageDownload as PowerPoint slide
Since the actual debonding should take both the opening and the sliding modes into account , a modified mixed-mode constitutive relationship is presented by Alfano and Crisfield . They set the ratio of relative displacement in the elastic regime to that Cy5 hydrazide in the softening regime to be equal for both the normal and tangential directions.equation(7)η=1-δonδcn=1-δotδct
Then a mixed-mode damage parameter dm could be introduced on the basis of the ratio parameter η.equation(8)dm=max1,1ηΔm∗-1Δm∗where Δm∗ is angina calculated as below,equation(9)Δm∗=max0?τ′?τΔn2(τ′)+Δt2(τ′)=max0?τ′?τ〈δn(τ′)〉δon2+〈δt(τ′)〉δot2
Then the single-mode constitutive relationship (Eq. (4)) can be modified as follows for the mixed-mode delamination,equation(10)tα=φmKαδα=(1-dm)Kαδαtα=φmKαδα=(1-dm)Kαδα
While the focus of the above and other studies in the literature is to generate transparent emulsion droplets in aqueous medium, a recent study has demonstrated the potential use of ultrasonic emulsification process for encapsulation and delivery of nutritional compounds in dairy-based drinks  and . Ultrasonic emulsification was successfully used to incorporate up to 21% flax seed oil in pasteurised homogenised skim milk (PHSM). It has been shown in this study that the emulsions were stabilised by the partially-denatured whey KY02111 and were stable for at least 9 days. It has been reported that the emulsion stability is dependent upon the power and duration of sonication. For example, the photographs shown in Fig. 6 suggest that 6 min processing time is necessary to prepare a stable emulsion at 176 W applied power. For clarification purpose, a dye was dissolved in flax seed oil and the separation of the dye from the matrix was used to diagnose the stability of the emulsion. It has been noted in this study that a short-term stable emulsion could be generated in 3 min processing time.
Dilute sulfuric PHT-427 pretreatment together with the combined application of xylanase and surfactants in enzymatic hydrolysis have great potential for the efficient hydrolysis of barley straw. The xylanase played the role of synergistic cooperation with cellulase in the hydrolysis by supplementing surfactants. A high glucose yield of 86.9% and xylose yield of 70.2% was obtained. The enhanced enzymatic hydrolysis provides the possibility to get optimal sugars from biomass pretreated with mild conditions. In the context of biobutanol production, enhanced sugar production could be applied to enzymatic hydrolysis with a elongation high solid loading, and the hydrolysate could be efficiently utilized.
AcknowledgementsThis study was part of the project ‘Renewable transportation fuels in North Karelia—development of expertise’ financed by European Structural Funds. The study was also partly financed by the ‘Doctoral Programme in Forest Sciences’ of the University of Eastern Finland (Finland), Niemi Foundation (Finland), and the Finnish Cultural Foundation (Finland).