Background Different stems implantation in ST-segmem elevation myocardial infarction （STEMI） patients may influence the long term prognosis by affecting vessel healings after stenting. The aim of this study was to e...Background Different stems implantation in ST-segmem elevation myocardial infarction （STEMI） patients may influence the long term prognosis by affecting vessel healings after stenting. The aim of this study was to evaluate the vessel healings after implantation of drug elming stems （DES） with biodegradable or durable polymer or of bare-metal stems （BMS） in patients with ache STEMI. Methods This study included 50 patients, who underwem follow up angiogram and optical coherence tomography （OCT） assessment about one year after percutaneous coronary intervemion （PCI） for STEMI. According to the initial stems types, these patients were classified to durable （n = 19） or biodegradable polymer sirolimus-eluting stems （n = 15）, or BMS （n = 16） groups. The conditions of stem struts coverage and malapposi- tion were analyzed with OCT technique. Results A total of 9003 struts were analyzed： 3299, 3202 and 2502 from durable or biodegradable polymer DES, or BMS, respectively. Strut coverage rate （89.0%, 94.9% and 99.3%, respectively）, malapposition presence （1.7%, 0.03% and 0 of struts, respectively） and average intimal thickness over struts （76 ± 12 μm, 161 ± 30 μm and 292 ± 29 μm, respectively） were significantly differem among different stent groups （all P 〈 0.001）. Conclusions Vessel healing status in STEMI patients is superior after implantation of biodegradable polymer DES than durable polymer DES, while both are inferior to BMS.展开更多
In the last years, biodiesel production has been on a steady increase due to it is renewable and biodegradable fuel. The process to obtain biodiesel can be carried out using different raw materials. It is conlmonly pe...In the last years, biodiesel production has been on a steady increase due to it is renewable and biodegradable fuel. The process to obtain biodiesel can be carried out using different raw materials. It is conlmonly performed by transesterification reaction of vegetable oils with methanol and using a homogeneous or heterogeneous catalyst. This work seeks to compare the results produced in transesterification of wasted cooking oil and chicken fat by homogeneous catalysis with NaOH. Due to in each case triglyceride comes from different raw materials, operation conditions differ slightly, which is more evident in the values used for the temperature. For chicken fat was used temperature variations between 35 ℃ and 55 ℃, varying catalyst in percentages between 0.3% and 0.7% with a molar ratio 6：1 in all cases and a reaction time of I h. Likewise, the conditions used in the tmnsesterification process of waste cooking oil were temperature between 50 ℃ and 60 ℃ with a molar ratio 6/1 and 9/1 for alcohol and oil, and catalyst percentage between 0.5% and 0.7% by weight. The yields obtained were between 78% and 94%, or 83% and 95%, for chicken fat and wasted cooking oil, respectively.展开更多
Succinic acid has recently emerged as an important chemical （commodity） because it can be used for the manufacturing of synthetic resins and biodegradable polymers and as an intermediate for chemical synthesis. Till...Succinic acid has recently emerged as an important chemical （commodity） because it can be used for the manufacturing of synthetic resins and biodegradable polymers and as an intermediate for chemical synthesis. Till date, succinic acid is mainly produced by chemical processes, however, due to the environmental concerns and the concepts of sustainability, researches are directed towards the production of succinic acid by microbial fermentation. The fact that carbon dioxide （CO2） is needed by the microorganisms for succinic acid production is another interesting feature. The fermentation was carried out with Actinobacillus succinogenes using a two-level fractional factorial design 2sl. The variables analyzed and their levels were： concentration of glucose, yeast extract, temperature, pH and agitation. The results show that the variables that more influenced on succinic acid production were pH, temperature and yeast extract.展开更多
Fossil fuels are non-renewable, and their quantities have been reducing because of pumping. On the other hand, the traffic is still developing and needs for fuels are growing. As a consequence people are forced to loo...Fossil fuels are non-renewable, and their quantities have been reducing because of pumping. On the other hand, the traffic is still developing and needs for fuels are growing. As a consequence people are forced to look for other sources of getting fuel. Additional reason for this has been steadily boosting the prices of crude oil and gas. Diesel, as fuel that is often used, is possible to produce from different feedstock （oil rape, soybean, sunflower, palm, waste animal fats, algae, etc）. In this paper, the author analyzes the possibility of obtaining biodiesel from algae and the feasibility of such a method of producing biodiesel. Algae for biodiesel production are analyzed and the systems in which they are growing are described. Experience in this area is described as well as opportunities for further development of technology for getting biodiesel from algae. Algae are very resistant and can grow virtually anywhere in the desert, in salt and fresh water and even in the waste water. Algae can reproduce quickly; they use C02 for photosynthesis and less water than other crops. Bio fuel from algae is biodegradable and contains no sulphur and it is not toxic.展开更多
Poly（L-lactic acid） （PLLA） and poly（e-caprolactone） （PCL） have been receiving much attention lately due to their biodegradability in human body as well as in the soil, also due to their biocompatibility, envir...Poly（L-lactic acid） （PLLA） and poly（e-caprolactone） （PCL） have been receiving much attention lately due to their biodegradability in human body as well as in the soil, also due to their biocompatibility, environmentally friendly characteristics and non-toxicity. Morphology of biodegradable polymers affects the rate of their biodegradation. A polymer that has high degree of crystallinity will degrade at a slower rate due to the inherent increased stability. PCL homopolymer crosslinking degree increases with increasing doses of high energy radiation. On the other hand, the irradiation ofPLLA homopolymer promotes mainly chain-scissions at doses below 250 kGy. In the present work, twin screw extruded films of PLLA and PCL biodegradable homopolymers and 50：50 （w：w） blend were electron beam irradiated using electron beam accelerator Dynamitron （E = 1.5 MeV） from Radiation Dynamics, Inc. at doses in the range of 50 kGy to 103 kGy in order to evaluate the effect of electron beam radiation. Wide-angle X-ray diffraction （WAXD） patterns of non irradiated and irradiated samples were obtained using a diffractometer Rigaku Denki Co. Ltd., Multiflex model; and Fourier transform infrared spectroscopy （FTIR） spectra was obtained using a NICOLET 4700, attenuated total reflectance （ATR） technique. By WAXD patterns of as extruded non irradiated and irradiated PLLA it was verified broad diffusion peaks corresponding to amorphous polymer. There was a slight increase of the mean crystallite size of PCL homopolymer with increasing radiation dose. PCL crystalline index （CI） decreased with radiation dose above 500 kGy. But then, PLLA CI increased with radiation dose above 750 kGy. From another point of view, PLLA presence on the 50：50 blend did not interfere on the observed mean crystallite size increase up to 250 kGy. From 500 kGy to 103 kGy the crystallite size of PCL was a little bigger in the blend than the homopolymer. In contrast, FTIR results have shown that this technique was not sensitive enough to observe the degradation promoted by ionizing radiation of the studied homopolymers and blends, and neither on the miscibility of the blends.展开更多
Due to its specificity, seasonality and location of large areas, the crops are exposed to the greatest degree of risks posed by climate change. To maintain stability and increase yields, it is imperative to implement ...Due to its specificity, seasonality and location of large areas, the crops are exposed to the greatest degree of risks posed by climate change. To maintain stability and increase yields, it is imperative to implement an innovative approach by which to optimize certain processes such as tillage, sowing and irrigation. The main tasks of innovative solutions are proposed to increase the soil water holding capacities in the root layer over a prolonged period of time, and improve the accuracy of the drilling process for row crops and vegetables by using biodegradable materials, and on this basis to optimize the irrigation by use of specialized software products to determine irrigation scheduling and irrigation requirements.展开更多
With the aim of creating biodegradable materials for medical devices clinical appointments with high hemocompatibility we have developed a new polymer product.The basis of this product is plasticized by polyethylene g...With the aim of creating biodegradable materials for medical devices clinical appointments with high hemocompatibility we have developed a new polymer product.The basis of this product is plasticized by polyethylene glycol bacterial copolymer of hydroxybutyrate and oxovalerate. A well-known antitbrombotic supplement--acetylsalicylic acid has been added to improve hemocompatibility in the polymer. The results of our studies showed a controlled prolonged separation of acetylsalicylic acid from polymeric material in the blood. We studied in vitro the dynamics of liberation of acetylsalicylic acid from polymeric coatings. It was shown that the concentration of polyethylene glycol and the thickness of the polymer layer can affect the rate of diffusion of acetylsalicylic acid from polymer films.展开更多
Bactericidal activity of some arginine based biodegradable polymers-PEURs （poly （ester urethane）s） and PEUs （poly （ester urea）s） with low cytotoxicity was studied in in vitro experiments. Various bacterial str...Bactericidal activity of some arginine based biodegradable polymers-PEURs （poly （ester urethane）s） and PEUs （poly （ester urea）s） with low cytotoxicity was studied in in vitro experiments. Various bacterial strains both Gram-positive and Gram-negative were used to explore the bactericidal activity of the cationic polymers. As the test objects, the following microorganisms were used： Bacillus subtilis, Staphylococcus aureus, Mycobacterium album, Pseudomonas fluorescens, Escherichia coli, Actinomyces griseus and Aspergillus niger. The obtained results showed that the new cationic polymers suppressed the growth of the studied microorganisms and the bactericidal activity of the tested cationic polymers strongly depending on their chemical structure.展开更多
Soil microbes are one of the most important determinants of allelopathic effects in the field. However, most studies testing the role of allelopathy in biological invasions did not consider the roles of soil microbes....Soil microbes are one of the most important determinants of allelopathic effects in the field. However, most studies testing the role of allelopathy in biological invasions did not consider the roles of soil microbes. Here we tested the hypothesis that soil microbes which can degrade allelochemicals may accumulate in soils over time by adaptation and therefore increase the degradation of allelochemicals and alleviate the allelopathic effects in biological invasions. As expected, soil microbes signifi- cantly decreased the allelopathic effects of leaf leachates of eight in the nine invasive plant species studied. In addition, Ageratina adenophora showed lower allelopathic effects in soil with long or intermediately invasion history than those in soil with short invasion history. The two main allelo- chemicals of the invader were degraded more rapidly with increasing invasion history in the soil. Correspondingly,biomass and activity of the soil microbes were higher in the soils with long invasion history than in that with short invasion history. Our results indicate that soil microbes may graduaUy adapt to the allelochemicals of Ageratina and alleviate its allelopathic effects and thus support the above hypothesis. It is necessary to consider the effects of soil microbes when testing the roles of allelopathy or the novel weapons hypothesis in biological invasions.展开更多
Scaffolds play a crucial role in tissue engineering. Biodegradable polymers with great processing flexibility are the predominant scaffolding materials. Synthetic biodegradable polymers with well-defined structure and...Scaffolds play a crucial role in tissue engineering. Biodegradable polymers with great processing flexibility are the predominant scaffolding materials. Synthetic biodegradable polymers with well-defined structure and without immunological concerns associated with naturally derived polymers are widely used in tissue engineering. The synthetic biodegradable polymers that are widely used in tissue engineering, including polyesters, polyanhydrides, polyphosphazenes, polyurethane, and poly(glycerol sebacate) are summarized in this article. New developments in conducting polymers, photoresponsive polymers, amino-acid-based polymers, enzymatically degradable polymers, and peptide-activated polymers are also discussed. In addition to chemical functionalization, the scaffold designs that mimic the nano and micro features of the extracellular matrix(ECM) are presented as well, and composite and nanocomposite scaffolds are also reviewed.展开更多
The use of nanotechnology in drug-delivery systems(DDS) is attractive for advanced diagnosis and treatment of cancer diseases. Biodegradable polymeric nanoparticles, for example, have promising applications as advance...The use of nanotechnology in drug-delivery systems(DDS) is attractive for advanced diagnosis and treatment of cancer diseases. Biodegradable polymeric nanoparticles, for example, have promising applications as advanced drug carriers in cancer treatment. In this review, we discuss the development of drug-delivery systems based on an amphiphilic principle mainly conducted by our group for anti-cancer drug delivery. We first briefly address the synthetic chemistry for amphiphilic biodegradable polymers. In the second part, we summarize progress in the application of self-assembled polymer micelles using amphiphilic biodegradable copolymers as anti-tumor drug carriers.展开更多
文摘Background Different stems implantation in ST-segmem elevation myocardial infarction （STEMI） patients may influence the long term prognosis by affecting vessel healings after stenting. The aim of this study was to evaluate the vessel healings after implantation of drug elming stems （DES） with biodegradable or durable polymer or of bare-metal stems （BMS） in patients with ache STEMI. Methods This study included 50 patients, who underwem follow up angiogram and optical coherence tomography （OCT） assessment about one year after percutaneous coronary intervemion （PCI） for STEMI. According to the initial stems types, these patients were classified to durable （n = 19） or biodegradable polymer sirolimus-eluting stems （n = 15）, or BMS （n = 16） groups. The conditions of stem struts coverage and malapposi- tion were analyzed with OCT technique. Results A total of 9003 struts were analyzed： 3299, 3202 and 2502 from durable or biodegradable polymer DES, or BMS, respectively. Strut coverage rate （89.0%, 94.9% and 99.3%, respectively）, malapposition presence （1.7%, 0.03% and 0 of struts, respectively） and average intimal thickness over struts （76 ± 12 μm, 161 ± 30 μm and 292 ± 29 μm, respectively） were significantly differem among different stent groups （all P 〈 0.001）. Conclusions Vessel healing status in STEMI patients is superior after implantation of biodegradable polymer DES than durable polymer DES, while both are inferior to BMS.
文摘In the last years, biodiesel production has been on a steady increase due to it is renewable and biodegradable fuel. The process to obtain biodiesel can be carried out using different raw materials. It is conlmonly performed by transesterification reaction of vegetable oils with methanol and using a homogeneous or heterogeneous catalyst. This work seeks to compare the results produced in transesterification of wasted cooking oil and chicken fat by homogeneous catalysis with NaOH. Due to in each case triglyceride comes from different raw materials, operation conditions differ slightly, which is more evident in the values used for the temperature. For chicken fat was used temperature variations between 35 ℃ and 55 ℃, varying catalyst in percentages between 0.3% and 0.7% with a molar ratio 6：1 in all cases and a reaction time of I h. Likewise, the conditions used in the tmnsesterification process of waste cooking oil were temperature between 50 ℃ and 60 ℃ with a molar ratio 6/1 and 9/1 for alcohol and oil, and catalyst percentage between 0.5% and 0.7% by weight. The yields obtained were between 78% and 94%, or 83% and 95%, for chicken fat and wasted cooking oil, respectively.
文摘Succinic acid has recently emerged as an important chemical （commodity） because it can be used for the manufacturing of synthetic resins and biodegradable polymers and as an intermediate for chemical synthesis. Till date, succinic acid is mainly produced by chemical processes, however, due to the environmental concerns and the concepts of sustainability, researches are directed towards the production of succinic acid by microbial fermentation. The fact that carbon dioxide （CO2） is needed by the microorganisms for succinic acid production is another interesting feature. The fermentation was carried out with Actinobacillus succinogenes using a two-level fractional factorial design 2sl. The variables analyzed and their levels were： concentration of glucose, yeast extract, temperature, pH and agitation. The results show that the variables that more influenced on succinic acid production were pH, temperature and yeast extract.
文摘Fossil fuels are non-renewable, and their quantities have been reducing because of pumping. On the other hand, the traffic is still developing and needs for fuels are growing. As a consequence people are forced to look for other sources of getting fuel. Additional reason for this has been steadily boosting the prices of crude oil and gas. Diesel, as fuel that is often used, is possible to produce from different feedstock （oil rape, soybean, sunflower, palm, waste animal fats, algae, etc）. In this paper, the author analyzes the possibility of obtaining biodiesel from algae and the feasibility of such a method of producing biodiesel. Algae for biodiesel production are analyzed and the systems in which they are growing are described. Experience in this area is described as well as opportunities for further development of technology for getting biodiesel from algae. Algae are very resistant and can grow virtually anywhere in the desert, in salt and fresh water and even in the waste water. Algae can reproduce quickly; they use C02 for photosynthesis and less water than other crops. Bio fuel from algae is biodegradable and contains no sulphur and it is not toxic.
文摘Poly（L-lactic acid） （PLLA） and poly（e-caprolactone） （PCL） have been receiving much attention lately due to their biodegradability in human body as well as in the soil, also due to their biocompatibility, environmentally friendly characteristics and non-toxicity. Morphology of biodegradable polymers affects the rate of their biodegradation. A polymer that has high degree of crystallinity will degrade at a slower rate due to the inherent increased stability. PCL homopolymer crosslinking degree increases with increasing doses of high energy radiation. On the other hand, the irradiation ofPLLA homopolymer promotes mainly chain-scissions at doses below 250 kGy. In the present work, twin screw extruded films of PLLA and PCL biodegradable homopolymers and 50：50 （w：w） blend were electron beam irradiated using electron beam accelerator Dynamitron （E = 1.5 MeV） from Radiation Dynamics, Inc. at doses in the range of 50 kGy to 103 kGy in order to evaluate the effect of electron beam radiation. Wide-angle X-ray diffraction （WAXD） patterns of non irradiated and irradiated samples were obtained using a diffractometer Rigaku Denki Co. Ltd., Multiflex model; and Fourier transform infrared spectroscopy （FTIR） spectra was obtained using a NICOLET 4700, attenuated total reflectance （ATR） technique. By WAXD patterns of as extruded non irradiated and irradiated PLLA it was verified broad diffusion peaks corresponding to amorphous polymer. There was a slight increase of the mean crystallite size of PCL homopolymer with increasing radiation dose. PCL crystalline index （CI） decreased with radiation dose above 500 kGy. But then, PLLA CI increased with radiation dose above 750 kGy. From another point of view, PLLA presence on the 50：50 blend did not interfere on the observed mean crystallite size increase up to 250 kGy. From 500 kGy to 103 kGy the crystallite size of PCL was a little bigger in the blend than the homopolymer. In contrast, FTIR results have shown that this technique was not sensitive enough to observe the degradation promoted by ionizing radiation of the studied homopolymers and blends, and neither on the miscibility of the blends.
文摘Due to its specificity, seasonality and location of large areas, the crops are exposed to the greatest degree of risks posed by climate change. To maintain stability and increase yields, it is imperative to implement an innovative approach by which to optimize certain processes such as tillage, sowing and irrigation. The main tasks of innovative solutions are proposed to increase the soil water holding capacities in the root layer over a prolonged period of time, and improve the accuracy of the drilling process for row crops and vegetables by using biodegradable materials, and on this basis to optimize the irrigation by use of specialized software products to determine irrigation scheduling and irrigation requirements.
文摘With the aim of creating biodegradable materials for medical devices clinical appointments with high hemocompatibility we have developed a new polymer product.The basis of this product is plasticized by polyethylene glycol bacterial copolymer of hydroxybutyrate and oxovalerate. A well-known antitbrombotic supplement--acetylsalicylic acid has been added to improve hemocompatibility in the polymer. The results of our studies showed a controlled prolonged separation of acetylsalicylic acid from polymeric material in the blood. We studied in vitro the dynamics of liberation of acetylsalicylic acid from polymeric coatings. It was shown that the concentration of polyethylene glycol and the thickness of the polymer layer can affect the rate of diffusion of acetylsalicylic acid from polymer films.
文摘Bactericidal activity of some arginine based biodegradable polymers-PEURs （poly （ester urethane）s） and PEUs （poly （ester urea）s） with low cytotoxicity was studied in in vitro experiments. Various bacterial strains both Gram-positive and Gram-negative were used to explore the bactericidal activity of the cationic polymers. As the test objects, the following microorganisms were used： Bacillus subtilis, Staphylococcus aureus, Mycobacterium album, Pseudomonas fluorescens, Escherichia coli, Actinomyces griseus and Aspergillus niger. The obtained results showed that the new cationic polymers suppressed the growth of the studied microorganisms and the bactericidal activity of the tested cationic polymers strongly depending on their chemical structure.
基金We are grateful to Da-Wen Li and Ailaoshan Station for Subtropical Forest Ecosystem Studies, Chinese Academy of Sciences for field assistance. This work was supported by the National Natural Science Foundation of China （31100410, 31470575 and 30830027）, the National Key Technology R＆D Program of China （2011BAD30B00）, and Chinese Academy Science 135 Program （XTBG-T01, F01）.
文摘Soil microbes are one of the most important determinants of allelopathic effects in the field. However, most studies testing the role of allelopathy in biological invasions did not consider the roles of soil microbes. Here we tested the hypothesis that soil microbes which can degrade allelochemicals may accumulate in soils over time by adaptation and therefore increase the degradation of allelochemicals and alleviate the allelopathic effects in biological invasions. As expected, soil microbes signifi- cantly decreased the allelopathic effects of leaf leachates of eight in the nine invasive plant species studied. In addition, Ageratina adenophora showed lower allelopathic effects in soil with long or intermediately invasion history than those in soil with short invasion history. The two main allelo- chemicals of the invader were degraded more rapidly with increasing invasion history in the soil. Correspondingly,biomass and activity of the soil microbes were higher in the soils with long invasion history than in that with short invasion history. Our results indicate that soil microbes may graduaUy adapt to the allelochemicals of Ageratina and alleviate its allelopathic effects and thus support the above hypothesis. It is necessary to consider the effects of soil microbes when testing the roles of allelopathy or the novel weapons hypothesis in biological invasions.
基金the financial support of the US National Institutes of Health(NIDCR DE015384,DE017689,DE022327)DOD(W81XWH-12-2-0008)+1 种基金the National Science Foundation of the United States(DMR-1206575)the National Natural Science Foundation of China(21304073)
文摘Scaffolds play a crucial role in tissue engineering. Biodegradable polymers with great processing flexibility are the predominant scaffolding materials. Synthetic biodegradable polymers with well-defined structure and without immunological concerns associated with naturally derived polymers are widely used in tissue engineering. The synthetic biodegradable polymers that are widely used in tissue engineering, including polyesters, polyanhydrides, polyphosphazenes, polyurethane, and poly(glycerol sebacate) are summarized in this article. New developments in conducting polymers, photoresponsive polymers, amino-acid-based polymers, enzymatically degradable polymers, and peptide-activated polymers are also discussed. In addition to chemical functionalization, the scaffold designs that mimic the nano and micro features of the extracellular matrix(ECM) are presented as well, and composite and nanocomposite scaffolds are also reviewed.
基金supported by the National Basic Research Program of China(2011CB606206)the National Natural Science Foundation of China(21372170,51133004 and 81361140343)+1 种基金the Recruitment Program ofGlobal Young Experts of China,the Setup Foundation of Sichuan University(YJ201317)the Excellent Young Teachers Program of SichuanUniversity(2082604164235)
文摘The use of nanotechnology in drug-delivery systems(DDS) is attractive for advanced diagnosis and treatment of cancer diseases. Biodegradable polymeric nanoparticles, for example, have promising applications as advanced drug carriers in cancer treatment. In this review, we discuss the development of drug-delivery systems based on an amphiphilic principle mainly conducted by our group for anti-cancer drug delivery. We first briefly address the synthetic chemistry for amphiphilic biodegradable polymers. In the second part, we summarize progress in the application of self-assembled polymer micelles using amphiphilic biodegradable copolymers as anti-tumor drug carriers.
