摘要:
A method for synthesizing a medical grade biodegradable material, poly(lactic-co-glycolic acid), copolycondensation of lactic acid and glycolic acid catalyzed by biomass creatinine. The present invention uses commercialized creatinine (a type of biomaterial organic guanidine compounds—the arginine metabolite creatinine (CR) in human body) as the catalyst and industrial lactic acid (LA, mass content 85%, aqueous solution) and glycolic acid (GA, 95%) as the monomer to synthesize the high biosafety of medical poly(lactic-co-glycolic acid) in terms of two steps polycondensation without solvent. The method of the present invention has the following characters: green technology is used, raw materials required are low in costs, operation is simple and convenient, and it is easy for industrialization; the catalyst, creatinine, used in the invention has high biocompatibility and biosafety, and no cytotoxicity; the poly(lactic-co-glycolic acid) synthesized is free of any metal and other toxic residues; Further, the molecular weight distribution for all synthesized products is narrow and the molecular weight is controllable within 1.8-17.7×104; and the poly(lactic-co-glycolic acid) synthesized is suitable for use as implantable material for hard tissue repair, surgical sutures, and the carrier for targeting drugs and controlled release drugs.
摘要:
Disclosed is a high molecular weight polylactic acid synthesized by using a method for synthesizing and catalytically-polycondensing bionic creatinine-guanidinium chloride. Creatinine is used as the material in a reaction with aqueous hydrochloric acid to synthesize a bionic creatinine-guanidinium salt catalyst, creatinine-guanidinium chloride (CR.Cl). The creatinine-guanidinium chloride synthesized is used as a catalyst, an industrial grade lactic acid (LA, 85% to 90%, aqueous solution) is used as a monomer, a solvent-free two-step polycondensation method is used to synthesize and afford metal-free and toxic residue-free polylactic acid featuring high biological safety and high molecular weight.
摘要:
A direct polycondensation method for medical biodegradable polylactic acid (PLA). The invention uses commercialized creatinine (a type of biomaterial organic guanidine compounds—the arginine metabolite creatinine in human body) as the catalyst and industrial lactic acid (mass content 85-90%, aqueous solution) as the monomer to synthesize the PLA in terms of second polycondensation without solvent. Instead of tin catalysts having cytotoxicity, the catalyst used in the invention has high biocompatibility and biosafety. The synthesized PLA does not contain any metal and other toxic components; therefore, it can be used as the carrier for targeting drugs and controlled release drugs. The green catalyst and green processing method (no solvent applied and no toxic products produced) are used to synthesize the green biodegradable PLA with high biosafety. The molecular weight distribution for all synthesized products is narrow and the molecular weight is controllable within 1.5-3.0×104.
摘要:
The present invention provides a direct polycondensation method for medical biodegradable polylactic acid (PLA) using creatinine catalyzed lactic acid. The invention uses commercialized creatinine (a type of biomaterial organic guanidine compounds—the arginine metabolite creatinine (CR) in human body) as the catalyst and industrial lactic acid (LA, mass content 85-90%, aqueous solution) as the monomer to synthesize the high biosafety of medical PLA in terms of second polycondensation without solvent (identity). Instead of tin catalysts having cytotoxicity, the catalyst used in the invention has high biocompatibility and biosafety. The synthesized PLA does not contain any metal and other toxic components; therefore, it can be used as the carrier for targeting drugs and controlled release drugs. In addition, the green catalyst and green processing method (no solvent applied and no toxic products produced) are used in the invention to synthesize the green biodegradable PLA with high biosafety. The polymerization reaction is simple and the raw materials required are low in costs, thus it is easy for industrialization. Further, the molecular weight distribution for all synthesized products is narrow and the molecular weight is controllable within 1.5-3.0×104.
摘要:
Disclosed is a high molecular weight polylactic acid synthesized by using a method for synthesizing and catalytically-polycondensing bionic creatinine-guanidinium chloride. Creatinine is used as the material in a reaction with aqueous hydrochloric acid to synthesize a bionic creatinine-guanidinium salt catalyst, creatinine-guanidinium chloride (CR.Cl). The creatinine-guanidinium chloride synthesized is used as a catalyst, an industrial grade lactic acid (LA, 85% to 90%, aqueous solution) is used as a monomer, a solvent-free two-step polycondensation method is used to synthesize and afford metal-free and toxic residue-free polylactic acid featuring high biological safety and high molecular weight.
摘要:
A method for synthesizing a medical grade biodegradable material, poly(lactic-co-glycolic acid), copolycondensation of lactic acid and glycolic acid catalyzed by biomass creatinine. The present invention uses commercialized creatinine (a type of biomaterial organic guanidine compounds—the arginine metabolite creatinine (CR) in human body) as the catalyst and industrial lactic acid (LA, mass content 85%, aqueous solution) and glycolic acid (GA, 95%) as the monomer to synthesize the high biosafety of medical poly(lactic-co-glycolic acid) in terms of two steps polycondensation without solvent. The method of the present invention has the following characters: green technology is used, raw materials required are low in costs, operation is simple and convenient, and it is easy for industrialization; the catalyst, creatinine, used in the invention has high biocompatibility and biosafety, and no cytotoxicity; the poly(lactic-co-glycolic acid) synthesized is free of any metal and other toxic residues; Further, the molecular weight distribution for all synthesized products is narrow and the molecular weight is controllable within 1.8-17.7×104; and the poly(lactic-co-glycolic acid) synthesized is suitable for use as implantable material for hard tissue repair, surgical sutures, and the carrier for targeting drugs and controlled release drugs.
摘要:
Message management and classification techniques are described. In one or more implementations, a message received from a sender for delivery via a user account is examined to extract one or more features of the message. A determination is then made as to whether the message corresponds to one or more categories based on the extracted features, the categories usable to enable features to be applied to the message in a user interface.
摘要:
A semiconductor device and a method for manufacturing the same are provided. In one embodiment, the method comprises: growing a first epitaxial layer on a substrate; forming a sacrificial gate stack on the first epitaxial layer; selectively etching the first epitaxial layer; growing and in-situ doping a second epitaxial layer on the substrate; forming a spacer on opposite sides of the sacrificial gate stack; and forming source/drain regions with the spacer as a mask.
摘要:
One or more techniques and/or systems are provided for defining a message behavior profile for a sender, which may be used to categorize messages from the sender. A message behavior profile may be defined based upon, for example, message distribution behavior of the sender (e.g., volume, frequency, variance in content amongst messages sent to recipients, etc.); recipient interactions with messages from the sender (e.g., message read rates, message response rates, etc.); unsubscription options comprised within messages from the sender; and/or other factors. In this way, the message behavior profile and/or features extracted from a message may be used to categorize a message from the sender (e.g., newsletter, commercial advertisements, alert, social network etc.). Categorized messages may be organized into folders, displayed or hidden within views, and/or processed based upon their respective categorizations.
摘要:
The invention discloses an electronic terminal and a ringtone prompt method for the electronic terminal. A control module of the electronic terminal instructs a ringtone sound source module to play a test ringtone signal, and instructs a ringtone channel switch system to switch all sound channels one by one to output the test ringtone signal; a sound collection module collects an exterior sound signal while each channel is outputting the test ringtone signal and feeds it back to a signal processing module; the signal processing module processes the intensity of the test ringtone signal therein; the control module determines the output channel of a prompt ringtone signal according to the processing result of the collected signal, instructs the ringtone channel switch system to switch to the determined output channel, and instructs the ringtone sound source module to play the prompt ringtone signal.