Hydroxyethyl chitosan （HE-chitosan） is a water-soluble derivative of chitosan with many apparent biological properties. For example, it is non-toxic and rapidly biodegradable. Moreover, HE-chitosan has advantages in...Hydroxyethyl chitosan （HE-chitosan） is a water-soluble derivative of chitosan with many apparent biological properties. For example, it is non-toxic and rapidly biodegradable. Moreover, HE-chitosan has advantages in water-solubility, moisture retention and gelling property due to its hydroxyethyl group. However, the biocompatibility and biodegradability of this multifimctional de- rivative have rarely been documented although they are critical for its application in biomedical and clinical treatments. The purpose of this work was to evaluate the biosafety of HE-chitosan, and draw important clues for its diverse applications. HE-chitosan was synthesized and characterized its chemical structure with FTIR. Its molecular weight （Mw） was determined by gel permeation chro- matography （GPC）, and its deacetylation degree （DD） was investigated through potentiometric analysis. The cytotoxicity of HE-chitosan on mouse fibroblast cell L929 was tested. The biocompatibility and biodegradability of HE-chitosan in rat and rabbit were evaluated. The FTIR results indicated that the hydroxyethyl groups were linked to C6 of chitosan. The GPC analysis confirmed that its Mw was about 90.01 kDa. It was also demonstrated that HE-chitosan had excellent biocompatibility and biodegradability in vivo and had no cytotoxicity on L929. These findings indicated that HE-chitosan can potentially be applied as a biomaterial in tissue engineering, drug delivery, and other biomedical fields.展开更多
An adenine nucleotide derivative 2-aminoadenosine 5＇-triphosphate was chemically synthesized through four steps and was characterized with 1H NMR, 31p NMR, 13C NMR, EA and FT-IR. Its ultraviolet and fluorescence prop...An adenine nucleotide derivative 2-aminoadenosine 5＇-triphosphate was chemically synthesized through four steps and was characterized with 1H NMR, 31p NMR, 13C NMR, EA and FT-IR. Its ultraviolet and fluorescence properties at various pH values were studied. Two pKa values for the compound were determined by the curves of UV absorption dependency on pH, Which were 0.68 and 4.83, respectively. The values were consistent with those calculated from ACD/Labs software. In addition, hydrolysis of the adenine nucleotide derivative in the catalysis of potato apyrase was studied. The competition of the ATP analogue with ATP for potato apyrase＇ active site was proved to be a sequential reaction mechanism.展开更多
The article presents a case study about thermal comfort in two public squares located in the coastal region of southeastern Brazil, within a post-occupational assessment context where it was sought to estimate the the...The article presents a case study about thermal comfort in two public squares located in the coastal region of southeastern Brazil, within a post-occupational assessment context where it was sought to estimate the thermal sensation and perception of the users generating systematized knowledge about the built environment. The objective is to instruct future interventions for improvement in the living condition where it is particularly important for the success of the activities predicted there. Surveys on thermal comfort along with goers of the squares were held on three consecutive days in April 2013 and February 2014 with microclimate monitoring of the places adopting the predictive PET （physiological equivalent temperature） index calculated based on the bioclimatic model Rayman. The obtained data set generated valuable information about the pattern of thermal comfort allowing understanding the analytical correlations between PET index, climate variables and the perception of comfort. The article seeks to contribute towards the recognition of bioclimatic specificities in the project process aimed to the improvement of the environmental and social performance of public squares and aspects that are relevant to the urban planners.展开更多
基金supported by the National Key Technology R&D Program of the Ministry of Science and Technology(2013BAB01B02)
文摘Hydroxyethyl chitosan （HE-chitosan） is a water-soluble derivative of chitosan with many apparent biological properties. For example, it is non-toxic and rapidly biodegradable. Moreover, HE-chitosan has advantages in water-solubility, moisture retention and gelling property due to its hydroxyethyl group. However, the biocompatibility and biodegradability of this multifimctional de- rivative have rarely been documented although they are critical for its application in biomedical and clinical treatments. The purpose of this work was to evaluate the biosafety of HE-chitosan, and draw important clues for its diverse applications. HE-chitosan was synthesized and characterized its chemical structure with FTIR. Its molecular weight （Mw） was determined by gel permeation chro- matography （GPC）, and its deacetylation degree （DD） was investigated through potentiometric analysis. The cytotoxicity of HE-chitosan on mouse fibroblast cell L929 was tested. The biocompatibility and biodegradability of HE-chitosan in rat and rabbit were evaluated. The FTIR results indicated that the hydroxyethyl groups were linked to C6 of chitosan. The GPC analysis confirmed that its Mw was about 90.01 kDa. It was also demonstrated that HE-chitosan had excellent biocompatibility and biodegradability in vivo and had no cytotoxicity on L929. These findings indicated that HE-chitosan can potentially be applied as a biomaterial in tissue engineering, drug delivery, and other biomedical fields.
文摘An adenine nucleotide derivative 2-aminoadenosine 5＇-triphosphate was chemically synthesized through four steps and was characterized with 1H NMR, 31p NMR, 13C NMR, EA and FT-IR. Its ultraviolet and fluorescence properties at various pH values were studied. Two pKa values for the compound were determined by the curves of UV absorption dependency on pH, Which were 0.68 and 4.83, respectively. The values were consistent with those calculated from ACD/Labs software. In addition, hydrolysis of the adenine nucleotide derivative in the catalysis of potato apyrase was studied. The competition of the ATP analogue with ATP for potato apyrase＇ active site was proved to be a sequential reaction mechanism.
文摘The article presents a case study about thermal comfort in two public squares located in the coastal region of southeastern Brazil, within a post-occupational assessment context where it was sought to estimate the thermal sensation and perception of the users generating systematized knowledge about the built environment. The objective is to instruct future interventions for improvement in the living condition where it is particularly important for the success of the activities predicted there. Surveys on thermal comfort along with goers of the squares were held on three consecutive days in April 2013 and February 2014 with microclimate monitoring of the places adopting the predictive PET （physiological equivalent temperature） index calculated based on the bioclimatic model Rayman. The obtained data set generated valuable information about the pattern of thermal comfort allowing understanding the analytical correlations between PET index, climate variables and the perception of comfort. The article seeks to contribute towards the recognition of bioclimatic specificities in the project process aimed to the improvement of the environmental and social performance of public squares and aspects that are relevant to the urban planners.
基金funded by the Tertiary Industry Water Intake Quota Research project in Beijing,administered by the Institute of Geographic Sciences and Natural Resources Research,CAS
