Identification and PID Control for a Class of Delay Fractional-order Systems

In this paper,a new model identification method is developed for a class of delay fractional-order system based on the process step response.Four characteristic functions are defined to characterize the features of the normalized fractionalorder model.Based on the time scaling technology,two identification schemes are proposed for parameters' estimation.The scheme one utilizes three exact points on the step response of the process to calculate model parameters directly.The other scheme employs optimal searching method to adjust the fractional order for the best model identification.The proposed two identification schemes are both applicable to any stable complex process,such as higher-order,under-damped/over-damped,and minimum-phase/nonminimum-phase processes.Furthermore,an optimal PID tuning method is proposed for the delay fractionalorder systems.The requirements on the stability margins and the negative feedback are cast as real part constraints(RPC)and imaginary part constraints(IPC).The constraints are implemented by trigonometric inequalities on the phase variable,and the optimal PID controller is obtained by the minimization of the integral of time absolute error(ITAE) index.Identification and control of a Titanium billet heating process is given for the illustration.

Postharvest Low Temperature Conditioning Reduces Peel Browning and Improves Fruit Quality in Storage and Subsequent Shelf Life of Huangguan Pear

Huangguan pear (Pyrus bretschneideri Rehd cv. Huangguan) is a pear cultivar that rapidly developed in China. However, rapid postharvest browning appearing in fruit peel and core during storage and shelf life pose a challenge for their marketing. The potential for low temperature conditioning (LTC) treatment to inhibit peel browning and improve quality of Huangguan pears in storage and shelf life was investigated. Pears were treated at 8℃ - 9℃ for 1, 3, 6 and 9 d, respectively, physiological indexes, including peel and core browning, core breakdown, malondialdehyde (MDA) content and ethanol content were determined and quality in storage period and shelf life was evaluated in this paper. LTC treatment alleviated peel browning and core browning either in storage or shelf life remarkably;it also delayed the decline of firmness, total soluble solids and titratable acidity in storage to some extent, inhibited ethanol and MDA content both in storage and shelf life effectively and maintained juiciness and crispness of pear fruit in shelf life. These results showed that LTC can serve as an important tool for the regulation of Huangguan pears external and internal quality in storage and shelf life with economic benefits and LTC treatment for 6 d was the optimum condition in the present study.

Therapeutic window of Qingkailing injection for focal cerebral ischemia/reperfusion injury

The time window in which a drug is effective varies between drugs. The present study investigated the therapeutic window of Qingkailing injection for focal cerebral ischemia/reperfusion in mice. Animals underwent middle cerebral artery occlusion and were injected with Qingkailing （1.5, 3, 6 mL/kg）. Infarct volume and neurological function were assessed after 24 hours of ischemia. In addition, to establish the therapeutic time window, mice were injected with 3 mL/kg Qingkailing at 0, 1, 3, 4, 6, 9 and 12 hours after occlusion. Results revealed that Qingkailing injection significantly reduced infarct volume and improved neurological function in model mice after cerebral infarction for up to 9 hours, demonstrating that the therapeutic window of Qingkailing injection can extend to 9 hours for cerebral ischemia/reperfusion in mice.

Crystal growth, spectroscopic characteristics, and Judd–Ofelt analysis of Dy:Lu_2O_3 for yellow laser

Dy：Lu2O3 was grown by the float-zone （Fz） method. According to the absorption spectrum, the Judd-Ofelt （JO） parameters Ω2, Ω4, and Ω6 were calculated to be 4.86 × 10-20 cm2, 2.02 × 10-20 cm2, and 1.76 ×10-20 cm2, respectively. The emission cross-section at 574 nm corresponding to the 4F9/2 →6H13/2 transition was calculated to be 0.53 ×10 20 cm2. The yellow （4F9/2 →6H13/2 transition） to blue （4F9/2 →6H15/2 transition） intensity ratio ranges up to 12.9. The fluorescence lifetime of the 4F9/2 energy level was measured to be 112.1 μs. These results reveal that Dy：Lu2O3 is a promising material for use in yellow lasers.

Efficacy of Chinese herbal medicine in functional dyspepsia: A meta-analysis of randomized, double-blind, placebo-controlled trials

Objective:To evaluate the efficacy and safety of Chinese herbal medicine(CHM)for the treatment of functional dyspepsia(FD).Methods:Web of Science,PubMed,EMBASE,Cochrane Library,and four other Chinese electronic databases,including China National Knowledge Infrastructure(CNKI),Chinese Biological Medical Database(CBM),Chinese Scientific Journals Database(VIP),and WanFang Database were used to search(up to Feb,2016)for randomized,double-blind,placebocontrolled trials recruiting adults with FD treated with CHM.Study selection,data extraction,quality assessment,and data analyses were conducted based on Cochrane standards using Review Manager software.Results:Fourteen publications(1424 patients)were included.Evidence revealed that CHM was more efficacious than the placebo in improving global dyspepsia symptoms(RR,1.45;95%CI,1.31e1.60),Chinese medicine syndrome(CMS)(RR,1.36;95%CI,1.23e1.50),and quality of life(SMD,0.30;95%CI,0.15e0.45)in FD patients.Furthermore,the difference in the incidence of adverse events between CHM and placebo groups had no statistical significance(RR,1.06;95%CI,0.66e1.70).Conclusion:This meta-analysis demonstrates that CHM has a therapeutic potential in treating FD with a certain safety.However,due to the restricted number of trials included,wellplanned,long-term studies are necessary to provide credible evidence.

Molecular mechanism of non-alcoholic fatty liver disease induced and aggravated by chronic stress through HSL/ATGL-FFA which promotes fat mobilization

Objective:To study the effects of social stress(CS)and social stress combined with high-fat diet on fat mobilization as a candidate mechanism for the induction or aggravation of non-alcoholic fatty liver disease(NAFLD).Methods:Thirty-two male Wistar rats(250±10 g)were randomly allocated to a blank control group(BC),a high-fat diet group(HFD),a CS group,and a combined CS and high-fat diet group(CS t HFD).Rats were sacrificed and tissues were collected after 8 weeks.Liver and body mass were measured and used to calculate the liver index.Serum aspartate aminotransferase(AST),alanine aminotransferase(ALT),and free fatty acids(FFAs)were measured.Liver sections were examined microscopically after oil red O and hematoxylin and eosin staining.The relative mRNA expression of acetyl-CoA carboxylase(ACCase),hydroxymethylglutaryl coenzyme A(HMG-CoA)reductase in liver,and hormone-sensitive lipase(HSL),and adipose triglyceride lipase(ATGL)in subcutaneous adipose tissue,were measured by real-time PCR.The liver concentrations of triglyceride,reactive oxygen species,and ACCase were measured by ELISA and HSL activity was determined using turbidimetry.Results:NAFLD developed in the CS,HFD,and CS t HFD groups,with the most severe NAFLD being in the CS t HFD group.Serum AST,ALT,and FFA,liver index,and hepatic triglyceride,FFA,and tumor necrosis factor-a were significantly higher in both the CS and CS t HFD groups.However,food intake and ACCase mRNA expression were lower.The mRNA expression of HSL and ATGL in adipose tissue was much higher,and HSL activity was higher in the CS group than in the BC group,and in the CS t HFD group than in the HFD group.Conclusion:We have successfully established two models of stress-induced NAFLD,suggesting stress can induce and aggravate NAFLD by promoting fat mobilization through upregulation of HSL and ATGL.

Xiaoqinglong decoction reduces dendritic cell differentiation and regulates the Th1/Th2 balance in a mouse model of allergic asthma

Background:Xiaoqinglong decoction(XQLD)is a classic Chinese medicinal formula that is widely used to treat allergic asthma.Recently,the use of XQLD to treat allergic asthma has inspired research to determine its mechanism of action.Because dendritic cells(DCs)and the T helper 1(Th1)/Th2 cytokine balance play important roles in allergic asthma,the present work aimed to assess how these immune system components are affected by XQLD.Methods:Thirty-six female BALB/C mice were randomly divided into three groups:an ovalbumin-based allergic asthma model group,a XQLD treatment group,and a control group.Histology was performed with haematoxylin and eosin staining and immunohistochemical staining.Bronchoalveolar lavage fluid and blood were collected from the animals and used to analyze the composition of inflammatory cells and expression levels of the cytokines interleukin(IL)-5 and IL-13.The thymic stromal lymphopoietin(TSLP)protein expression was assessed by western blot analysis,and the Gata3 and Tbx21 mRNA levels were assessed by polymerase chain reaction.Results:Compared with the OVA group,the levels of TSLP expression,IL-5,IL-13,and immunoglobulin E in the XQLD group were lower(all P<.01).The level of IL-4-expressing cells(Th2 cells)was lower(P=.0013),and the percentage of IFN-g-expressing cells(Th1 cells)was higher in the XQLD group compared with those in the OVA group(P=.0065).In addition,XQLD increased the expression of Tbx21 mRNA and decreased the expression of Gata3 mRNA in the lungs compared with the OVA group(both P<.01).Conclusion:These findings suggest that XQLD may ameliorate the course of allergic asthma by regulating the Gata3/Tbx21 balance and inhibiting TSLP expression,changes which are indicative of an altered Th1/Th2 balance.Thus,the clinical effectiveness of XQLD in treating allergic asthma may be due to its regulation of Th1/Th2 balance.

Crystal growth and spectral properties of Tb：Lu2O3

The crystal growth,x-ray diffraction pattern,absorption spectrum,emission spectrum,and fluorescence lifetime of a Tb：Lu2O3 single crystal were studied.Excited at 483 nm,the peak absorption cross-section was calculated to be 3.5×10（-22）cm2,and the full width at half maximum was found to be 2.85 nm.The Judd-Ofelt（J-O）intensity parameters 2,4,and 6 were computed to be 3.79×10（-20）cm2,1.30×10（-20）cm2,and 1.08×10（-20）cm2,with a spectroscopic quality factor 4/6 being 1.20.The emission cross-sections of green emission around 543 nm and yellow emission around 584 nm were calculated to be 9.43×10（-22）cm2 and 1.32×10（-22）cm2,respectively.The fluorescence lifetimeτexp of -5D4 was fitted to be 1.13 ms.The data suggest that the Tb：Lu2O3 crystal could be a potential candidate for green and yellow laser operation.

Effects of ephedra asarum aconite decoction on Th1/Th2 balance in two animal models of allergic rhinitis

Objective:Ephedra asarum aconite decoction is used in the clinical treatment of allergic rhinitis.We investigated the effects of ephedra asarum aconite decoction on Th1/Th2 balance in two animal models of allergic rhinitis and in activated T cells in vitro.Methods:Animal models of simple and compound kidney yang deficiency types of allergic rhinitis were treated with ephedra asarum aconite decoction to observe the efficacy of this traditional Chinese medicine formula on allergic symptoms,serum cytokines,and tissue RNA levels.We also cultured and activated T cells from the mouse.After treatment with ephedra asarum aconite decoction,we tested the proliferation and differentiation of T cells.Results:Ephedra asarum aconite decoction relieved allergy symptoms in both types of animal models,and was more effective in the compound kidney yang deficiency model In addition to its anti-allergic efficacy,ephedra asarum aconite decoction significantly improved the health status of animals in the compound kidney yang deficiency groups,significantly made their bodyweight rising up,and significantly increased the T-bet mRNA/GATA-3 mRNA ratio.Moreover,ephedra asarum aconite decoction promoted the proliferation of activated T cells and inhibited the differentiation to Th2 cells in vitro.Conclusions:Ephedra asarum aconite decoction regulates the balance of Th1/Th2 to ameliorate allergic conditions.

Biological mechanisms underlying the liver's regulation of emotions in women: A study using the Trier Social Stress Test

Objective:Research on the biological mechanisms by which the liver controls dispersion and regulates emotion usually focuses on psychological stress.This study investigated the biological mechanisms underlying the liver's regulation of emotion using the Trier Social Stress Test (TSST).Differences in subjective stress,subjective emotion,and physiological responses were examined between healthy women (Group A) and depressed women with liver qi stagnation syndrome (Group B).Method:Subjects were 72 women who met the inclusion criteria after physical examination.The EPQ-RSC,BAI,and BDI-21 were used to assess personality and emotion.Subjects completed a 5-point scale to measure subjective stress.Heart rate and heart rate variability were measured.To measure changes in activity of the locus coeruleus-norepinephrine (LCNE)/autonomic nervous system and the HPA axis,saliva samples were collected at the end of the rest and preparation periods,and 5 time pionts after the TSST task.The PAD Emotion Scale was completed at 4 time points before and after the TSST task.Saliva cortisol was tested.These indexes were compared between the two groups.Results:There were 33 subjects in Group A and 39 subjects in Group B.Subjects in Group B had lower levels of stress,pleasure,and dominance,but higher arousal (after the task:P <.05).They also had higher saliva cortisol levels,slower heart rate,higher BVP,and more stable RMSSD and SDNN.Conclusion:In relation to mood,the liver's regulation of emotion mainly affects negative emotional experience and the sense of control Regarding the biological mechanisms underlying the liver's regulation of emotion,the activity of the LC-NE/autonomic nervous system in women is more obvious in response to psychological stress when the dispersion of the liver is normal.The activity of the HPA axis in women is more obvious in response to psychological stress when the dispersion of the liver is abnormal.

Proteomics analysis of IBS-D with spleen and kidney yang deficiency

Objective:To investigate the molecular mechanism underlying the development of diarrhea-predominant irritable bowel syndrome (IBS-D) with spleen and kidney yang deficiency (SKYD) using a proteomics approach.Methods:Male Sprague-Dawley rats (n =22) were divided into IBS-D (n =12) and normal control (n =10) groups.SKYD was then modeled in IBS-D rats by a combination of acetic acid enema,bondage,rectal dilation,tail stimulation,and Senna gavage.Colon tissue samples were subsequently collected and examined by Q Exactive mass spectrometry to identify differentially expressed proteins between the two groups.Results:The occurrence of SKYD/IBS-D was associated with ribosomal protein S23 (Rps23),protein phosphatase 2 catalytic subunit alpha (Pp2a),and growth factor receptor-bound protein 2 (Grb2),which are involved in the ribosome,neurotrophin signaling,and Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathways.Conclusion:These data suggest that SKYD/IBS-D pathophysiology likely involves inflammation,cell growth,apoptosis,stress granule formation,immune activation,loss of epithelial cell integrity,and visceral hypersensitivity.

Crystal growth,spectral properties and Judd-Ofelt analysis of Pr:CaF_(2)-YF_(3)

The 0.6 at.%Pr^(3+)-doped CaF_(2)-YF_(3)crystal was successfully grown by the temperature gradient technique(TGT).X-ray diffraction analysis showed that the grown crystal still had cubic structure.The absorption spectrum,emission spectrum,Judd-Ofelt analysis and fluorescence decay curve at room temperature were discussed.The fluorescence lifetime of Pr:CaF_(2)-YF_(3)crystal was 45.46µs,and theσem·τof ^(3)P0→^(3)H_(6) and ^(3)P0→^(3)F_(2) transitions were calculated to be 80.92×10^(−20) cm^(2)·µs and 388.7×10^(−20) cm^(2)·µs,respectively.The FWHMs are 20.1 nm and 6.8 nm,which are higher than those of Pr:LiYF_(4),Pr:LiLuF_(4),Pr:LiGdF_(4) and Pr:BaY_(2)F_(8) crystals.The results show that the Pr:CaF_(2)-YF_(3)crystal is expected to achieve 605 nm orange light and 642 nm red light laser operation.

Qinzhi Zhudan formula improves memory and alleviates neuroinflammation in vascular dementia rats partly by inhibiting the TNFR1-mediated TNF pathway

Objective: The Qinzhi Zhudan formula(QZZD) exhibits a prominent therapeutic effect in the treatment of vascular dementia(VaD). This study combined a network pharmacology approach and experimental validation to identify the underlying biological mechanism of QZZD against VaD.Methods: Male Wistar rats received bilateral common carotid artery occlusion(BCCAO) surgery, and after4 weeks of intragastric administration of QZZD, the therapeutic effect was assessed using the Morris water maze test and cerebral blood flow(CBF) assessment. Hematoxylin and eosin staining, Nissl staining, and electron microscopy were used to measure the histopathological changes in the neurons of rats. The effect of QZZD treatment on hippocampal neurotransmitters was assessed by high-performance liquid chromatography with electrochemical detection and liquid chromatography mass spectrometry.Immunofluorescence was used to observe VaD-induced microglia activation. The inflammatory cytokine levels were assessed by enzyme linked immunosorbent assay. Western blot was used to examine the TNFR1-mediated TNF pathway, which was screened out by network pharmacology analysis.Results: QZZD treatment alleviated pathological changes and neuronal damage in VaD rats and attenuated their cognitive impairment. In addition, QZZD increased CBF and the expression of acetylcholine and 5-hydroxytryptamine in the hippocampal region. Notably, QZZD inhibited microglial activation and the expression of IL-6 and TNF-a. Network pharmacology and western blot indicated that QZZD inhibited the levels of TNFR1, NF-κBp65, p-ERK, TNF-a, and IL-6, which are related to the TNFR1-mediated TNF signaling pathway.Conclusion: QZZD clearly improved learning and memory function, reduced brain pathological damage,elevated CBF and hippocampal neurotransmitter levels, and alleviated neuroinflammation of VaD rats partly by inhibiting the TNFR1-mediated TNF pathway, indicating its potential value in the clinical therapy of VaD.

Liangxue Xiaoban decoction and its disassembled prescriptions ameliorate psoriasis-like skin lesions induced by imiquimod in mice via T cell regulation

Objective:To explore the therapeutic capacity of the Liangxue Xiaoban(LXXB)decoction and its disassembled prescriptions in the modulation of T cell subsets and recurrence-related indexes of psoriasis using a psoriasis-like mouse model.Methods:The psoriasis model was generated by the treatment of BALB/c mice(n=48)with imiquimod.Mice were divided into six groups:control,psoriasis model,tripterygium glycosides,LXXB decoction,Liangxue decoction,and Qingqi decoction.After the intervention period,the interleukin(IL)-17A,IL-22,and interferon-γ levels in mice were examined and hematoxylin and eosin staining was conducted to determine pathological changes in the skin tissues.T cell subset changes in the skin-draining lymph nodes were analyzed using flow cytometry,and the expression levels of the associated transcription factors and recurrence-related indexes in the skin tissues were determined using a polymerase chain reaction.Results:LXXB decoction attenuated the levels of CD8^(+)T,Th17,and Th1 cells and induced an increase in the Th2 and Treg cell levels.The disassembled prescriptions promoted or inhibited specific subsets of T cells to improve the symptoms of psoriasis.Notably,the LXXB and Liangxue decoctions suppressed the expression of IL-22 at both the gene and protein levels and restored the CD103 and IL-15 expressions in the skin tissue to the normal range.Conclusion:LXXB decoction exerted significant immunoregulatory effects on T cell subsets and improved the recurrence-related indexes.Interestingly,the Liangxue prescription appeared to have a therapeutic advantage in terms of Th17 modulation and psoriasis recurrence,while the Qingqi prescription performed better in Treg immunoregulation.

Biologic basis of TCM syndromes and the standardization of syndrome classification

Traditional Chinese medicine(TCM)syndrome is an integral and essential component of TCM theory,and goes beyond philosophic concepts.This article reviews the concept of TCM syndromes and summarizes research findings on the biologic foundation of syndromes.In addition,insight is provided into the promotion of standardization of syndrome classification by enforcing uniformity of TCM terminology,applying standardized diagnostic criteria and operating procedures to minimize subjective effects.Also incorporating interdisciplinary approaches such as data mining and structure modeling,as well as integrating findings on biomarker research are discussed.Consideration is made of the fundamental TCM aspects of syndrome elements,symptoms,phenotypic features,as well as diseases,to form an integral process in the diagnostic path.We believe that better understanding of the biologic basis of the TCM syndrome and standardization of syndrome classification will improve diagnosis,which in turn will enhance therapeutic efficacy and disease prognosis.

Mahuang Xixin Fuzi decoction protects against ovalbumin-induced allergic rhinitis by inhibiting type 2 innate lymphoid cells in mice

Objective:As a traditional herbal formula,Mahuang Xixin Fuzi decoction(MXFD)has been used to treat allergic rhinitis(AR).It regulates the transcription factor GATA3 in T cells,blocks Th2 skewing and rebalances the Th1/Th2 immunity.Type 2 innate lymphoid cells(ILC2s)are closely associated with GATA3.However,it remains unknown whether ILC2s could be one mechanism through which MXFD acts.We sought to elucidate the efficacy and mechanism of action of this decoction in AR treatment.Methods:Forty C57BL/6J female mice were equally divided into control,model,loratadine-and MXFDtreated groups in random.AR was induced by ovalbumin(OVA),and then treatment with loratadine or MXFD was administered.AR scores were evaluated and compared before and after treatment.Pathological changes in the nasal mucosa and lung were observed using hematoxylin-eosin staining of tissue samples.Activation of ILC2 in nasal mucosa was assessed by immunofluorescence and quantitative polymerase chain reaction analysis.ILC2 cell count in lungs was measured by flow cytometry and levels of interleukin-(IL)4,IL-5 and IL-13 in serum were detected by ELISA.Results:The decoction alleviated the symptoms of AR in mice,improved vascular congestion and expansion,glandular hyperplasia and inflammatory cell infiltration in mouse nasal mucosa and slowly improved the interstitial pneumonia and lesions.Meanwhile,MXFD reduced the number and percentage of ILC2s in the nasal mucosa and lungs,downregulated the expression of GATA3 mRNA and RORa mRNA,and reduced the related inflammatory cytokine levels,including IL-4,IL-5 and IL-13.Conclusion:These data suggest that inhibition of ILC2s by MXFD may be an important means by which to treat AR.

Effects of the menstrual cycle and neuroticism on women's sadness emotion and physiological responses based on an emotion-inducing experiment

Objective:To investigate the diversity of experiences of sadness emotion and physiological responses among female college students with high neuroticism (HN) and low neuroticism (LN) during the late luteal phase (LLP) and early follicular phase (EFP).Methods:Forty-two participants were classified as the HN group and 41 as the LN group based on their neuroticism score (Eysenck Personality Questionnaire Short Scale for Chinese).Participants watched sadness-inducing experimental films during the LLP and EFP.Results:The HN group showed similar sadness intensities in both phases.The LN group showed higher sadness intensity in the LLP than the EFP.The LN group's sadness scale assessments were lower than the HN group in both phases.The blood volume pulse in the HN group fell in both the LLP and EFP (both P <.001).The root mean square standard deviation of NN intervals rose in the EFP in the HN group before and after watching experimental films (P =.027),but fell in the LN group (P >.05).Between-group comparisons showed heart rate was significantly lower in the HN group than the LN group during EFP (P =.009),but there were no statistically significant differences in subjective experience and physiological data during LLP.The HN group had stronger sadness feelings and greater sadness arousal than the LN group during EFP.There were significant associations between menstrual cycle-related changes in sadness ratings and changes in physiological outcomes.Conclusion:Women with HN have less fluctuation in sadness than those with LN during the menstrual cycle,but experience strong sadness feelings in the LLP.Women with HN show stronger physiological responses in the EFP than those with LN,and have the highest responses in the LLP.

Qingre Lishi Tuihuang therapy for acute icteric hepatitis B: A systematic review

Objective:To assess the efficacy of Qingre Lishi Tuihuang therapy (QLTT) for acute icteric hepatitis B infection.Methods:Eight electronic databases were searched from inception to December 2016 with no language restrictions for reports of randomized controlled trials evaluating the effect of QLTT treating acute icteric hepatitis B.Two researchers independently extracted detailed data and assessed methodological quality.ReviewManager 5.3.0 software was used to analyze the data.Results:A total of 13 randomized controlled trials involving 2238 participants were included in this review.The methodological quality was generally poor.The results indicated that supplemented Yinchenhao decoction combined with non-specific treatments was more effective in improving the cure rate (risk ratio =1.80;95% CI 1.21-2.68) and reducing the serum levels of total bilirubin (mean difference =-29.74;95% CI-31.91 to-27.57) and aspartate aminotransferase.Other self-made prescriptions conforming to QLTT plus non-specific treatments had beneficial effect for acute icteric hepatitis B in curing this disease (risk ratio =1.48;95% CI 1.27-1.73),as well as for negative seroconversion of HBeAg (risk ratio =1.39;95% CI 1.11-1.74).Supplemented Yinchenhao decoction plus non-specific treatments was more effective than other self-made prescriptions conforming to QLTT in reducing serum total bilirubin level.Conclusion:Qingre Lishi Tuihuang therapy appears to improve effect based on non-specific treatments for the treatment of acute icteric hepatitis B.However,it is premature to draw confirmative conclusions,owing to the poor methodological quality and high clinical heterogeneity of the included trials.Further well-designed clinical randomized controlled trials with large sample sizes should be undertaken.

生物降解热塑性弹性体的分子结构设计与性能研究

本文以来源于生物质资源的脂肪族饱和二元醇(1,3-丙二醇、1,4-丁二醇)、饱和二元酸(丁二酸、己二酸和癸二酸)为原料,采用熔融缩聚和扩链反应成功制得一种由结晶型脂肪族饱和聚酯预聚体(HPE)和无定形脂肪族饱和聚酯预聚体(SPE)嵌段而成的生物降解热塑性弹性体(BTPE).研究结果表明,该饱和脂肪族BTPE具有较宽的使用温度范围和低硬度、高弹性等特征. BTPE的玻璃化转变温度在-50℃左右,熔点在105℃以上,初始热分解温度在340℃以上;BTPE的100%定伸回复率大于85%, 300%定伸循环拉伸回复率在75%以上,断裂伸长率可达1100%,拉伸强度在7.5~9.6 MPa,硬度在56~73 HA.在脂肪酶降解液中降解15天, BTPE的失重率可达68%;在自然土壤环境条件下降解120天, BTPE的失重率在57%以上.噻唑蓝(MTT)比色法测试结果表明, BTPE无明显细胞毒性,为一级合格.本文制备的BTPE在环境友好材料和生物医用材料领域具有广阔的应用前景.

Combination of wound healing with 1-methylcyclopropene and wound detection by iodine solution to maintain the quality of sweet potato during long-term storage

Wound healing treatment after harvest is a critical step to protect sweet potatoes from pathogens.The method of phloroglucinol staining is commonly used for detecting callus.However,this method is not easy to identify the degree of callus as the color change is not obvious compared with non-curing roots for some cultivars.A new method based on the principle of starch test by iodine was developed for the detection of wound healing.After healing,the reducing sugar content increased while the starch content decreased to a lower level compared to that of the non-curing roots.Moreover,the antioxidant capacity of the sweet potato after wound healing was higher than that in the control.Wound healing combined with ethylene,1-methylcyclopropene(1-MCP),chlorpropham or abscisic acid were studied for inhibiting sprout of sweet potato root caused by high temperature during curing.The results showed ethylene and 1-MCP treatment had no negative effect on wound healing.Moreover,1-MCP treatment was the most effective one on the suppression of sprouting and decay of sweet potato.The results indicate that iodine solution staining is a useful and rapid method to identify the wound healing extent,and 1-MCP treatment can effectively inhibit root sprouting during wound healing and the subsequent long-term storage.