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排序方式: 共有781条查询结果,搜索用时 406 毫秒
31.
Gopal Jeya Ravikumar Dhanalakshmi Murugan Anbarasu Viswanathan Vinitha Vajiravelu Sivamurugan 《印度化学会志》2022,99(1):100291
Chemical recycling of plastic wastes is top among the effective management of the solid wastes. Particularly the post-consumer polyethylene terephthalate (PET) plastic wastes mainly generated from the disposal of beverage bottles and placed third most produced polymeric waste. However, PET wastes could be chemically recycled using several types of homo-/heterogeneous acid or base catalysts, and an effective recycling process has yet to be achieved. Therefore, the present short review is intended to display recent reports on the depolymerization of PET polymer wastes. The review aimed to cover glycolysis and aminolytic depolymerization using various catalytic systems. There is a wide spectrum of catalytic systems such as metal oxides, ionic liquids, organic bases, nanoparticles, porous materials and microwave-assisted rapid depolymerization methods have been developed toward the yield enhancement of the depolymerized products. Ideologically, the present review would benefit the researchers in familiarizing themselves with the latest developments in this field. 相似文献
32.
Christos Liolios Christos Sachpekidis Antonios Kolocouris Antonia Dimitrakopoulou-Strauss Penelope Bouziotis 《Molecules (Basel, Switzerland)》2021,26(6)
Multimeric ligands consisting of multiple pharmacophores connected to a single backbone have been widely investigated for diagnostic and therapeutic applications. In this review, we summarize recent developments regarding multimeric radioligands targeting integrin αvβ3 receptors on cancer cells for molecular imaging and diagnostic applications using positron emission tomography (PET). Integrin αvβ3 receptors are glycoproteins expressed on the cell surface, which have a significant role in tumor angiogenesis. They act as receptors for several extracellular matrix proteins exposing the tripeptide sequence arginine-glycine-aspartic (RGD). Cyclic RDG peptidic ligands c(RGD) have been developed for integrin αvβ3 tumor-targeting positron emission tomography (PET) diagnosis. Several c(RGD) pharmacophores, connected with the linker and conjugated to a chelator or precursor for radiolabeling with different PET radionuclides (18F, 64Cu, and 68Ga), have resulted in multimeric ligands superior to c(RGD) monomers. The binding avidity, pharmacodynamic, and PET imaging properties of these multimeric c(RGD) radioligands, in relation to their structural characteristics are analyzed and discussed. Furthermore, specific examples from preclinical studies and clinical investigations are included. 相似文献
33.
Clayton A. Whitmore Mariam I. Boules William J. Behof Justin R. Haynes Dmitry Koktysh Adam J. Rosenberg Mohammed N. Tantawy Wellington Pham 《Molecules (Basel, Switzerland)》2021,26(8)
Promethazine, an antihistamine drug used in the clinical treatment of nausea, has been demonstrated the ability to bind Abeta in a transgenic mouse model of Alzheimer’s disease. However, so far, all of the studies were performed in vitro using extracted tissues. In this work, we report the design and synthesis of a novel [11C]promethazine PET radioligand for future in vivo studies. The [11C]promethazine was isolated by RP-HPLC with radiochemical purity >95% and molar activity of 48 TBq/mmol. The specificity of the probe was demonstrated using human hippocampal tissues via autoradiography. 相似文献
34.
Theranostics is a precision medicine which integrates diagnostic nuclear medicine and radionuclide therapy for various cancers throughout body using suitable tracers and treatment that target specific biological pathways or receptors. This review covers traditional theranostics for thyroid cancer and pheochromocytoma with radioiodine compounds. In addition, recent theranostics of radioimmunotherapy for non-Hodgkin lymphoma, and treatment of bone metastasis using bone seeking radiopharmaceuticals are described. Furthermore, new radiopharmaceuticals for prostatic cancer and pancreatic cancer have been added. Of particular, F-18 Fluoro-2-Deoxyglucose (FDG) Positron Emission Tomography (PET) is often used for treatment monitoring and estimating patient outcome. A recent clinical study highlighted the ability of alpha-radiotherapy with high linear energy transfer (LET) to overcome treatment resistance to beta--particle therapy. Theranostics will become an ever-increasing part of clinical nuclear medicine. 相似文献
35.
Zhibo Liu Maral Pourghiasian Mark Alex Radtke Joseph Lau Dr. Jinhe Pan Gemma M. Dias Dr. Donald Yapp Dr. Kuo‐Shyan Lin Prof. Dr. Francois Bénard Prof. Dr. David M. Perrin 《Angewandte Chemie (International ed. in English)》2014,53(44):11876-11880
A new zwitterionic organotrifluoroborate is appended to three radiosynthons that afford undergo facile bioconjugation to several clinically relevant peptides and one enzyme inhibitor. Molecularly complex bioconjugates are 18F‐labeled in a single aqueous step in rapid time (<15 min) without HPLC purification to afford tracers in good yields (>200 mCi, 20–40 %) at high specific activity (≥3 Ci/μmol) and at >98 % purity. PET imaging shows in vivo stability and tumor uptake. 相似文献
36.
Dr. Xinghai Ning Dr. Wonewoo Seo Dr. Seungjun Lee Dr. Kiyoko Takemiya Dr. Mohammad Rafi Dr. Xuli Feng Dr. Daiana Weiss Dr. Xiaojian Wang Larry Williams Vernon M. Camp Malveaux Eugene Prof. W. Robert Taylor Prof. Mark Goodman Prof. Niren Murthy 《Angewandte Chemie (International ed. in English)》2014,53(51):14096-14101
A positron emission tomography (PET) tracer composed of 18F‐labeled maltohexaose (MH18F) can image bacteria in vivo with a sensitivity and specificity that are orders of magnitude higher than those of fluorodeoxyglucose (18FDG). MH18F can detect early‐stage infections composed of as few as 105 E. coli colony‐forming units (CFUs), and can identify drug resistance in bacteria in vivo. MH18F has the potential to improve the diagnosis of bacterial infections given its unique combination of high specificity and sensitivity for bacteria. 相似文献
37.
To improve the glass transition temperature (Tg) and heat resistance of polyethylene terephthalate (PET) bottle, poly (ethylene glycol 1,4-cyclohexane dimethylene isosorbide terephthalate) (PEICT) with a unique cyclic structure was introduced into PET. The miscibility of the PET/PEICT blends and their feasibility as a heat resistant bottle were investigated. The introduction of PEICT into PET increases the Tg and the PET/PEICT blends exhibit a single Tg, indicating good miscibility between PEICT and PET. Furthermore, the Tg and crystallinity of the PET/PEICT blends can be adjusted by controlling the amount of PEICT added. The PET/PEICT blends were transparent in the visible light range (no significant change in transparency) because the blends were truly miscible as confirmed by Fox equation. As expected, the introduction of PEICT into PET bottle allows for improved heat resistance and shape stability due to the rigid molecular structure and chirality of the two tetrahydrofuran rings in the isosorbide group of PEICT. Based on our results, the as-prepared PET/PEICT blends with controllable high heat resistance can be used as a cost-effective alternative material for various hot-filling conditions in the beverage industry by adjusting the optimal ratio of PEICT to PET for each product (e.g. fruit juice, tea). 相似文献
38.
Manuel A. Treto-Suárez Yoan Hidalgo-Rosa Eduardo Schott Ximena Zarate Dayan Páez-Hernández 《International journal of quantum chemistry》2020,120(3):e26083
The turn-on luminescent chemosensor [2-Hydroxy-1-naphthaldehyde-(2-pyridyl) hydrazone] (L), selective to Al3+ ions, was studied by means of density functional theory (DFT) and time-dependent-DFT quantum mechanics calculations. The UV-Vis absorption and the radiative channel from the adiabatic S1 excited state were assessed in order to elucidate the selective sensing mechanism of L to Al3+ ions. We found that twisted intramolecular charge transfer (TICT) and photoelectron transfer (PET), which alter the emissive state, are responsible for the luminescence quenching in L. After coordination with Al3+, the TICT is blocked, and PET is no longer possible. So, the emission of the coordination complex is activated, and a fluorescence effect enhanced by chelation is observed. For compounds with Zn2+ and Cd2+, the luminescence quenching is caused by PET, while for Ni2+, ligand to metal charge transfer is the prominent mechanism. To go into more detail, the metal-ligand interaction was analyzed via the Morokuma-Ziegler energy decomposition scheme and the natural orbital of chemical valence. 相似文献
39.
Peter Roselt Carleen Cullinane Wayne Noonan Hassan Elsaidi Peter Eu Leonard I. Wiebe 《Molecules (Basel, Switzerland)》2020,25(23)
Vitamin E, a natural antioxidant, is of interest to scientists, health care pundits and faddists; its nutritional and biomedical attributes may be validated, anecdotal or fantasy. Vitamin E is a mixture of tocopherols (TPs) and tocotrienols (T-3s), each class having four substitutional isomers (α-, β-, γ-, δ-). Vitamin E analogues attain only low concentrations in most tissues, necessitating exacting invasive techniques for analytical research. Quantitative positron emission tomography (PET) with an F-18-labeled molecular probe would expedite access to Vitamin E’s biodistributions and pharmacokinetics via non-invasive temporal imaging. (R)-6-(3-[18F]Fluoropropoxy)-2,7,8-trimethyl-2-(4,8,12-trimethyltrideca-3,7,11-trien-1-yl)-chromane ([18F]F-γ-T-3) was prepared for this purpose. [18F]F-γ-T-3 was synthesized from γ-T-3 in two steps: (i) 1,3-di-O-tosylpropane was introduced at C6-O to form TsO-γ-T-3, and (ii) reaction of this tosylate with [18F]fluoride in DMF/K222. Non-radioactive F-γ-T-3 was synthesized by reaction of γ-T-3 with 3-fluoropropyl methanesulfonate. [18F]F-γ-T-3 biodistribution in a murine tumor model was imaged using a small-animal PET scanner. F-γ-T-3 was prepared in 61% chemical yield. [18F]F-γ-T-3 was synthesized in acceptable radiochemical yield (RCY 12%) with high radiochemical purity (>99% RCP) in 45 min. Preliminary F-18 PET images in mice showed upper abdominal accumulation with evidence of renal clearance, only low concentrations in the thorax (lung/heart) and head, and rapid clearance from blood. [18F]F-γ-T-3 shows promise as an F-18 PET tracer for detailed in vivo studies of Vitamin E. The labeling procedure provides acceptable RCY, high RCP and pertinence to all eight Vitamin E analogues. 相似文献
40.
Over the last several years, the number of concepts and technologies enabling the production of environmentally friendly products (including materials, consumables, and services) has expanded. One of these ways is cradle-to-cradle (C2C) certifiedTM. Life cycle assessment (LCA) technique is used to highlight the advantages of C2C and recycling as a method for reducing plastic pollution and fossil depletion by indicating the research limitations and gaps from an environmental perspective. Also, it estimates the resources requirements and focuses on sound products and processes. The C2C life cycle measurements for petroleum-based poly (ethylene terephthalate) (PET) bottles, with an emphasis on different end-of-life options for recycling, were taken for mainland China, in brief. It is considered that the product is manufactured through the extraction of crude oil into ethylene glycol and terephthalic acid. The CML analysis method was used in the LCIA for the selected midpoint impact categories. LCA of the product has shown a drastic aftermath in terms of environmental impacts and energy use. But the estimation of these consequences is always dependent on the system and boundary conditions that were evaluated throughout the study. The impacts that burden the environment are with the extraction of raw material, resin, and final product production. Minor influences occurred due to the waste recycling process. This suggests that waste degradation is the key process to reduce the environmental impacts of the production systems. Lowering a product’s environmental impact can be accomplished in a number of ways, including reducing the amount of materials used or choosing materials with a minimal environmental impact during manufacture processes. 相似文献