2021 Vol. 36, No. 1
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Potato protein (PP) and xanthan gum (XG) were used as raw materials.The optimal preparation conditions of xanthan gum microgel (PP-XGM) were determined through different pH value,heat treatment conditions,and potato protein/xanthan gum mass ratio.The structure of the PP-XGM prepared under this condition was characterized.The stability kinetic index was used as an indicator to study its emulsification stability.The results showed that the best preparation conditions for PP-XGM were PP/XG mass ratio of 1:1,pH value 3.0,and 80℃ water bath heating for 30 min.Compared with PP-XG,PP-XGM had larger particle size,smaller polydispersity coefficient and more uniform particle distribution.Compared with PP,the maximum absorption wavelength λmax of PP-XG and PP-XGM had a different degree of blue shift,and the fluorescence intensity FI of PP-XGM had the most significant decrease.Using projection electron microscopy,it was found that PP-XGM had a core-shell structure.Under the same oil phase volume fraction,the emulsion stability of PP-XGM was significantly higher than that of PP.
The effects of different freezing storage time (0 d,10 d,20 d,30 d) on the water content (Fw),water distribution and existence state,thermodynamic characteristics and texture characteristics in the dough were studied.And the correlation between them was explored through principal component analysis and correlation analysis.The results showed that the moisture state of the dough changed significantly with the increase of the frozen storage time.Fw,strongly-bound water content (A21) and free water (A23) increased,the lateral relaxation time of weakly-bound water (T22) and free water (T23) in the dough shifted to the left.After frozen storage,the thermal stability (To,Tc and ΔH) of the dough was improved,the hardness,gumminess and chewiness were increased,and the cohesiveness was reduced.The change of the internal moisture and thermal characteristics of the dough during the frozen storage period caused the improvement of the change value of the dough texture properties PC1,which represented the dough quality deteriorated.
Based on the knowledge of starch structure and retrogradation mechanism,this study evaluated the impact of exogenous components on starch retrogradation.As well,multiple analytical techniques including thermal analysis,spectral analysis and microscopic imaging were applied to determine the retrogradation of starch from macroscopic and molecular level.This study indicated that starch retrogradation could be affected by various exogenous components such as non-starch carbohydrate,salt,protein and lipid.However,starch-based foods was a complicated system and each component may interact with starch molecules during storage,thus it was necessary to further investigate the mechanism of starch retrogradation under complicated model changes rather than simple model system.Furthermore,current researchers normally revealed the starch retrogradation with single analysis technology,and common analysis techniques still have limitations such as single analysis index and difficulty in operation.Therefore,it was invaluable to measure starch retrogradation behaviors with combined techniques according to the information of food samples in practical application,which was helpful for a comprehensive understanding on the changes of starch retrogradation properties,hence impeding the retrogradation degree of starchy-foods and prolong their shelf-life.
To investigate the effect of heat aging time on the flavor components of tobacco sheet concentrated liquid,firstly,the concentrated liquid was treated at the constant temperature of 70℃ for 24 h,48 h and 72 h,respectively,then the routine chemical components (total sugar,amino acid,reducing sugar and nicotine) were determined and the flavor compositions were determined by GC-MS.The results showed that,after heat aging treatment,the mass concentration of total sugar,amino acid and reducing sugar decreased,while there was no significant change in nicotine massconcentration,and the massconcentration and type of flavor composition increased.The optimal treatment time was 48 h,and at this time,the concentrations of alcohol,acid,esters,ketones and aldehydes compounds in the concentrated liquid were 143.47 times,26.10 times,1.62 times,2.92 times and 15.76 times those concentrations in the original liquid.The total amount of flavor compositions were 44 kinds,and the total mass concentration was 891.79 μg/mL.
In order to improve the stability control level of the filter ventilation rate of the spraying glue-splicing machine,the factors affecting the stability of the ventilation area (no-glue area) were studied by using variance analysis,regression analysis and other methods,with the spraying glue pressure and the splicing temperature as variables.The results showed that the spraying glue pressure would affect the amount of tipping glue and the total area of ventilation area and ventilation rate,the best control range was 1000~1200 hPa.The splicing temperature would affect the degree of melting and diffusion of the filter rod glue and further the effective ventilation area (no-glue area) and ventilation rate.There existed differences between the effective ventilation area(no-glue area) and different machine of the same model,which was one of the most important factors causing the fluctuation of filter ventilation rate between machines.The consistency of the spraying glue pressure and the splicing temperature between the machines would be beneficial for the ensurance of the effective ventilation area and the stability of the filter ventilation rate.
The range analysis of orthogonal experiment method was used to study the effects of cylinder drying process parameters (drying temperature in cylinder,water content after cutting and HT (tunnel type tobacco temperature and humidification device) vapor pressure) on cut tobacco filling value,structure and sensory quality.And the three cylinder drying process parameters were optimized.The results showed that the importance ranking of key process parameters on filling value was established,which was HT vapor pressure > water content after cutting > drying temperature in cylinder.The individual degree of influence on structure of cut tobacco was ranked,which was HT vapor pressure > drying temperature in cylinder > water content after cutting.The influence degree that each factor works on sensory quality was sorted,which was water content after cutting > drying temperature in cylinder > HT vapor pressure.The effect of HT vapor pressure on filling value and structure of cut tobacco was the most significant,but on sensory quality was the least significant.In order to increase filling value and reduce the influence on sensory quality,the HT vapor pressure could be set on 0.40 MPa,the water content after cutting 21.0%,and the drying temperature in cylinder on 140℃.Under this optimal combination,the filling value of cut tobacco was increased by 0.21 cm3/g.
To understand the pollutants distribution of in the urban channel,5 sampling points were set in a certain reach of an urban channel,and parameters including DO,pH value,and temperature were measured on site in four seasons.The distribution of organic matter,nitrogen and sulfur pollutants in overlying water,pore water and sediment were measured.Results showed that the dissolved oxygen and temperature fluctuated in different seasons,while pH was always in weak alkaline.The organic matter,ammonia nitrogen,nitrate nitrogen,sulfate existed in the urban channel.Among them,the content of organic matter in the sediment was relatively small,which mainly existed in the overlying water and pore water,and varied greatly along the season.The concentration was distributed in 10.0~99.6 mg/L and 21.2~85.2 mg/L,respectively.Ammonia nitrogen mainly existed in pore water,and its content was relatively high in spring and summer,with the average value reaching to 173.7 mg/L in summer.Ammonia nitrogen content increased in the sediment to 1.34 mg/L and 1.42 mg/g,respectively in autumn and winter.Nitrate nitrogen mainly existed in the sediment,and its concentration was relative high in spring and autumn,with the average value as 2.84 mg/g and 2.27 mg/g,respectively.The distribution of sulfate was positively correlated with ammonia nitrogen,which also mainly existed in pore water.Sulfate in the pore water showed a similar variation trend with ammonia in different seasons,which reached the highest value as 600.3 mg/L in Summer,and correspondingly got the lowest value in sediment as 0.57 mg/g.
A sequencing batch bioreactor (SBR) was used to treat pentachlorophenol (PCP) wastewater with the co-metabolic carbon source of methanol,and the influent PCP was controlled as 10 mg/L.In addition,another SBR only supplied methanol was set as control.The effects of PCP on sludge acute toxicity and microbial community were studied by the luminescent bacterium acute toxicity bioassy and denaturing gradient gel electrophoresis technique,and the function of dominant microbes on sludge acute toxicity was deeply analyzed.Results showed that during the period of 1-19 days,the sludge activity was significantly inhibited after injecting into 10 mg/L PCP in influent,the sludge flocs were disintegrated and the PCP was difficult to degrade.The effluent chemical oxygen demands (COD) and sludge acute toxicity under PCP stress were significantly higher than the control.The regeneration of sludge activity was slow due to the PCP contamination.No PCP was added during 20-32 days and 2 mg/L PCP was added during 33-75 days,the removal of influent COD and PCP was still poor.The adsorbed PCP in sludge causing the increase of sludge acute toxicity was only one of the reasons.The metabolic intermediates of PCP and secretive secondary metabolites by the enriched dominant microbes should not be ignored in the process of PCP degradation,which played an important role in causing the sludge acute toxicity.
The basic physical and chemical indicators such as pH value,organic matter content,free iron oxide content,soil mechanical composition,cation exchange capacity of the three kinds of soils in different regions were measured,and the kinetics of the three kinds of soils adsorbing Cu2+ in wastewater were studied.The results showed that red soil was acidic and had the highest free iron oxide content,black soil was neutral and its cation exchange capacity was the highest,brown soil was neutral and its organic matter content was the highest;compared with red soil and brown yellow soil,the adsorption process of black soil on Cu2+ was more in line with the second-order kinetic equation and more suitable for Cu2+ adsorption material.
Aiming at the multi-dimensional and strong coupling problem of design and manufacturing caused by the high dimensionality of systems and large number of units of complex mechanical products,a module partition method based on spectral clustering algorithm was proposed.The hierarchical decomposition of products was realized based on the function-flow-structure decomposition method,and fuzzy mathematics was used to define the correlation between feature elements.On this basis,the association relation model of product parts based on numerical design structure matrix was constructed.By introducing the spectral clustering algorithm, the component clustering problem was transformed into the optimal division problem of the graph, and the eva-luation index of module division based on the average cohesion within the module and the average coupling between the modules was constructed to realize the module division of the products. The results of the examples showed that the method could effectively reduce the complexity of the design and manufacturing of complex mechanical products, and the method was scientifically effective.
Taking China National Knowledge Infrastructure (CNKI) and Web of Science (WOS) journal database as data sources, the annual publication volume of the research literature, author-institution cooperation distribution, research hotspots, and evolution trends from the domestic and foreign research literature on module division from 2000 to 2019 were visually analyzed with the CiteSpace software to draw scientific knowledge graph.It was pointed out that the research in the field of module division was paid close attention by seniors at home and abroad,and it experienced the following three stages:the initial exploration period (2000-2008), the rapid growth period (2009-2015), and the steady development period (2016-2019).From the perspective of the distribution of core authors and research institutions, it was found that China and the United States had the most outstanding research results in the field of module division. It indicated that China had become the backbone of this field in the international stage and the developed countries such as the United States were still the main research groups.The domestic and foreign research focused on the product's green module division, product design, mass customization, etc. However, foreign researches focused on the multi-disciplinary field,such as complex network, multi-objective optimization and biological network modularity.The domestic researches focused on theoretical methods of the module division with a narrow application scope.The future research will be conducted on key words such as national gene network, dynamic analysis, digital twin, etc. Among them, solving the organization and layout of the complex product's life cycle modules as well as applying digital twins to grasp the granularity of product function modules will be the focus and direction for the future research.
In order to study the flow law of smoke generated by fire after passing through several top structures such as smoke barriers,FSD numerical simulation method was used to compare the smoke spreading situation of the long-narrow space model in the case of no smoke barrier,single smoke barrier and multi smoke barrier.The velocity field distribution of smoke migration and the flow rate change in different sections were studied.The results showed that the time for smoke to reach the end of the long-narrow space were 15.9 s,17.1 s,18.8 s and 25.5 s,respectively,in the case of no smoke barrier and 1,2 and 4 smoke barriers.The reason why smoke barriers retarded the smoke spreading was that the top structures such as smoke barriers could reduce the relative flow velocity of smoke layer and lower air layer,which reduced the entrainment of air and the amount of flue gas generated; the retarding effect of multi smoke barrier was better than that of single barrier,and the smoke spreading speed was slower.
In order to solve the problem that the chamfer size of spiral bevel gears cannot be precisely controlled,a method for chamfering the tooth top with a conical cutter was proposed.This method established the tooth crest equation, and derived the tool path equation based on this. According to the taper angle of the conical cutter and the length of the chamfer, the position of the tool tip point and the tool axis vector could be calculated through geometric transformation.From this, the machining path of the tool was determined to complete the chamfering of tooth top. Simulation results showed that under three different chamfer parameters, the chamfer shape error was not more than 0.05 mm, which improved the chamfer accuracy, and could flexibly control the chamfer size.
Founded in 1986, bimonthly
Administered by:The Education Department Henan Province
Sponsored by:Zhengzhou University of Light Industry
Editor-in-chief:Wei Shizhong
Executive Editor-in-Chief:Zou Lin
Deputy Editor-in-Chief:Qu Shuanghong
Edited & published by:Editorial Department of Journal of Light Industry
CN 41-1437/TS
ISSN 2096-1553
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