Noble-metal nanoparticles (NPs) (such as Au, Ag, Pd, and Pt) have been the subject of intense research because their unique physiochemical properties are different from those of their bulk counterparts [1] and various applications are anticipated in sensing, [2] imaging, [3] cancer therapy, [4] optical data storage, [5] and catalysis. [6] However, it is well known that free noble-metal NPs have high surface energies and tend to aggregate and fuse; as a result the intriguing properties observed for the NPs disappear and difficulties arise for longterm storage, processing, and applications. Therefore, great efforts have been devoted to develop novel strategies to stabilize NPs, [7] and the most common approach is to coat noble-metal NPs with either organic or inorganic shells. These shells not only endow NPs with high stability but also offer them additional functionalities. As an example, in addition to good stability and biocompatibility, the mesoporous silica shells that are currently broadly used have high surface area and tunable pore size and volume, which can accommodate analytes and drug molecules. [7, 8] Unfortunately, the amorphous structure of silica and its own characteristics determine that it may be used only as a carrier, stabilizer, and ligand linker. In order to break through the limitations and develop a wide range of applications, it is necessary to search for new types of shell materials that not only have properties similar to those of porous silica but also impart new functionalities.In addition to high specific surface area and tunable pore size and volume, metal-organic frameworks (MOFs) have many exciting characteristics including structural adaptivity and flexibility, ordered crystalline pores, and multiple coordination sites, and offer various functions such as chemical separation, [9] gas storage, [10] drug delivery, [11] sensing, [12] and catalysis, [13] which originate from the limitless choice of building blocks. [14] Recently, MOFs have been used as functional materials to fabricate nanostructures with noble-metal NPs by either embedding NPs in the MOF matrices or encapsulating NPs within the MOF layers. [15] Nevertheless, effective control over the dispersibility of NPs within MOFs as well as the morphology and size of the composite products still presents significant challenges. For example, to our knowledge, there are few reports about the construction of well-defined core-shell noble-metal@MOF NPs, [15f,g] and none on the successful synthesis of core-shell noble-metal@-
Triterpenoids are a highly diverse group of natural products and used particularly as medicine. Here, a strategy combining stepwise metabolic engineering and transcriptional control was developed to strengthen triterpenoid biosynthesis in Saccharomyces cerevisiae. Consequently, an efficient biosynthetic pathway for producing β‐amyrin, a commercially valuable compound and precursor of triterpenoids, was constructed through expressing a plant‐derived β‐amyrin synthase. Introducing a heterologous squalene monooxygenase greatly dragged intermediate metabolite squalene toward β‐amyrin. Increasing squalene pool by overexpressing IPP isomerase, FPP, and squalene synthase further enhanced β‐amyrin synthesis of 49‐folds. Through reconstructing the promoters with the binding site of transcription factor UPC2, directed transcriptional regulation on engineered pathway was availably achieved, resulting in β‐amyrin titer increased by 65‐folds. Using ethanol fed‐batch fermentation, β‐amyrin titer was finally improved up to 138.80 mg/L with a yield of 16.30 mg/g dry cell, almost 185 and 232 and folds of the initially engineered strain, respectively. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3172–3179, 2015
Noble-metal nanoparticles (NPs) (such as Au, Ag, Pd, and Pt) have been the subject of intense research because their unique physiochemical properties are different from those of their bulk counterparts [1] and various applications are anticipated in sensing, [2] imaging, [3] cancer therapy, [4] optical data storage, [5] and catalysis.[6] However, it is well known that free noble-metal NPs have high surface energies and tend to aggregate and fuse; as a result the intriguing properties observed for the NPs disappear and difficulties arise for longterm storage, processing, and applications. Therefore, great efforts have been devoted to develop novel strategies to stabilize NPs, [7] and the most common approach is to coat noble-metal NPs with either organic or inorganic shells. These shells not only endow NPs with high stability but also offer them additional functionalities. As an example, in addition to good stability and biocompatibility, the mesoporous silica shells that are currently broadly used have high surface area and tunable pore size and volume, which can accommodate analytes and drug molecules. [7, 8] Unfortunately, the amorphous structure of silica and its own characteristics determine that it may be used only as a carrier, stabilizer, and ligand linker. In order to break through the limitations and develop a wide range of applications, it is necessary to search for new types of shell materials that not only have properties similar to those of porous silica but also impart new functionalities.In addition to high specific surface area and tunable pore size and volume, metal-organic frameworks (MOFs) have many exciting characteristics including structural adaptivity and flexibility, ordered crystalline pores, and multiple coordination sites, and offer various functions such as chemical separation, [9] gas storage,
CdS quantum dots (CdSQDs) were generated inside the network structure of poly (N-isopropylacrylamide)-co-(acrylic acid) (pNIPAm-co-AAc) microgels and their ability to photocatalytically degrade organic dyes was evaluated using rhodamine B (RhB).
An iron meteorite collected from the floor of Daling River, Chaoyang City, Liaoning Province, northeast of China reveals many micro images of ancient Greek mythology from different angle, showing the ideas, arts and technology of 2000-3000 years before.
Objective: To investigate the changes of calcitonin (CT) and calcitonin gene-related peptide (CGRP) in patients with medullary thyroid carcinoma (MTC). Methods: Fifty-eight cases of MTC were selected and the relationship between the CT levels and metastasis was investigated. The immunohistochemical method was used to detect the expression of CT and CGRP in the 58 samples of MTC tissues. The CT and CGRP in 30 newly diagnosed MTC inpatients were measured before operation and in the first few days after operation using a radioimmunoassy. Results: (1) The rate of residual tumor had a significant difference between the normal serum CT group one month after operation and the elevated group at the same period (P <0.01).(2) Immunohistochemical study revealed the positive rate of CT was about 98%, and that of the CGRP was 87.8%. (3) Part of the patients had an elevated CGRP levels while CT levels was normal. (4) The serum CT levels were decreased to a stable range one week after operation. Conclusion: CT is a useful index to evaluate the efficacy of surgical treatment. The measurement of serum CGRP is helpful in the diagnosis of MTC, especially for those whose preoperative CT levels are normal.Medullary thyroid carcinoma (MTC) is a malignant tumor of the parafollicular cells of the thyroid and has a poorer prognosis in thyroid cancer. Calcitonin (CT) secreted by thyroid parafollicular cells remains the cornerstone of clinical management as a serum tumor marker for MTC, but the nature of the changes of CT after operation is not clear. Also in some patients with MTC, they have a normal preoperative CT level. Calcitonin gene-related peptide (CGRP) is an alternate product of the CT gene, so it is a possible tumor marker for MTC [1,2] .In this study, in order to offer a basis for the diagnosis, treatment and prognosis for MTC patients, an immunohistochemical investigation for CT and CGRP was performed on tumor tissues from 58 patients with MTC. A radioimmunoassy was used to investigate the pattern of changes of CT and CGRP before and after operation.
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