添加剂有机胺对丙烯选择性氧化制丙烯醛催化剂活性的影响

采用共沉淀法制备丙烯选择性氧化制丙烯醛催化剂,考察有机胺的加入对丙烯选择性氧化制丙烯醛催化性能的影响。结果表明,添加有机胺后,催化剂活性在维持不变的情况下,选择性显著提高。采用扫描电镜、X射线衍射、吡啶吸附红外光谱和N₂物理吸附表征等对不同催化剂的物化性能进行表征。结果发现,添加有机胺后,催化剂比表面积略有下降,但催化剂表面的L酸性中心强度明显增加,对催化剂活性影响不大;另一方面,MoO₃结晶度的下降与(Co_0.7Fe_0.3)(MoO₄)结晶度的上升对催化剂选择性均是积极因素。同时孔容的减小以及大孔比例增加更有利于主反应产物的脱附,能抑制深度氧化物的生成。     

Genome Mining‐Directed Activation of a Silent Angucycline Biosynthetic Gene Cluster in Streptomyces chattanoogensis

Genomic sequencing of actinomycetes has revealed the presence of numerous gene clusters seemingly capable of natural product biosynthesis, yet most clusters are cryptic under laboratory conditions. Bioinformatics analysis of the completely sequenced genome of Streptomyces chattanoogensis L10 (CGMCC 2644) revealed a silent angucycline biosynthetic gene cluster. The overexpression of a pathway‐specific activator gene under the constitutive ermE* promoter successfully triggered the expression of the angucycline biosynthetic genes. Two novel members of the angucycline antibiotic family, chattamycins A and B, were further isolated and elucidated. Biological activity assays demonstrated that chattamycin B possesses good antitumor activities against human cancer cell lines and moderate antibacterial activities. The results presented here provide a feasible method to activate silent angucycline biosynthetic gene clusters to discover potential new drug leads.     

Genome Mining of the Hitachimycin Biosynthetic Gene Cluster: Involvement of a Phenylalanine‐2,3‐aminomutase in Biosynthesis

Hitachimycin is a macrolactam antibiotic with (S)‐β‐phenylalanine (β‐Phe) at the starter position of its polyketide skeleton. To understand the incorporation mechanism of β‐Phe and the modification mechanism of the unique polyketide skeleton, the biosynthetic gene cluster for hitachimycin in Streptomyces scabrisporus was identified by genome mining. The identified gene cluster contains a putative phenylalanine‐2,3‐aminomutase (PAM), five polyketide synthases, four β‐amino‐acid‐carrying enzymes, and a characteristic amidohydrolase. A hitA knockout mutant showed no hitachimycin production, but antibiotic production was restored by feeding with (S)‐β‐Phe. We also confirmed the enzymatic activity of the HitA PAM. The results suggest that the identified gene cluster is responsible for the biosynthesis of hitachimycin. A plausible biosynthetic pathway for hitachimycin, including a unique polyketide skeletal transformation mechanism, is proposed.     

Materials and surface engineering to control bacterial adhesion and biofilm formation: A review of recent advances

Bacterial adhesion to surfaces and subsequent biofilm formation are a leading cause of chronic infections and biofouling. These processes are highly sensitive to environmental factors and present a challenge to research using traditional approaches with uncontrolled surfaces. Recent advances in materials research and surface engineering have brought exciting opportunities to pattern bacterial cell clusters and to obtain synthetic biofilms with well-controlled cell density and morphology of cell clusters. In this article, we will review the recent achievements in this field and comment on the future directions.     

Genome-Wide Identification of PRP Genes in Apple Genome and the Role of MdPRP6 in Response to Heat Stress

Plant proline-rich proteins (PRPs) are cell wall proteins that occur in the plant kingdom and are involved in plant development and stress response. In this study, 9 PRP genes were identified from the apple genome and a comprehensive analysis of the PRP family was conducted, including gene structures, phylogenetic analysis, chromosome mapping, and so on. The expression of MdPRPs varied among tissues and in response to different types of stresses. MdPRP4 and MdPRP7 were induced by five detected stress treatments, including heat, drought, abscisic acid, cold, and salt; the expression patterns of the others varied under different types of stress. Subcellular localization showed that MdPRPs mainly functioned in the cytoplasm, except for MdPRP1 and MdPRP5, which also functioned in the nucleus. When MdPRP6 was overexpressed in tobacco, the transgenic plants showed higher tolerance to high temperature (48 °C) compared with wild-type (WT) plants. The transgenic plants showed milder wilting, a lower accumulation of electrolyte leakage, MDA and ROS, and a higher level of chlorophyll and SOD and POD activity, indicating that MdPRP6 may be an important gene in apples for heat stress tolerance. Overall, this study suggested that MdPRPs are critically important for the ability of apple responses to stresses.     

Low Expression of Mitofusin 1 Gene Leads to Mitochondrial Dysfunction and Embryonic Genome Activation Failure in Ovine-Bovine Inter-Species Cloned Embryos

Inter-species somatic cell nuclear transfer (iSCNT) is significant in the study of biological problems such as embryonic genome activation and the mitochondrial function of embryos. Here, we used iSCNT as a model to determine whether abnormal embryo genome activation was caused by mitochondrial dysfunction. First, we found the ovine-bovine iSCNT embryos were developmentally blocked at the 8-cell stage. The reactive oxygen species level, mitochondrial membrane potential, and ATP level in ovine-bovine cloned embryos were significantly different from both bovine-bovine and IVF 8-cell stage embryos. RNA sequencing and q-PCR analysis revealed that mitochondrial transport, mitochondrial translational initiation, mitochondrial large ribosomal subunit, and mitochondrial outer membrane genes were abnormally expressed in the ovine-bovine embryos, and the mitochondrial outer membrane and mitochondrial ribosome large subunit genes, mitochondrial fusion gene 1, and ATPase Na+/K+ transporting subunit beta 3 gene were expressed at lower levels in the ovine-bovine cloned embryos. Furthermore, we found that overexpression and knockdown of Mfn1 significantly affected mitochondrial fusion and subsequent biological functions such as production of ATP, mitochondrial membrane potential, reactive oxygen species and gene expressions in cloned embryos. These findings enhance our understanding of the mechanism by which the Mfn1 gene regulates embryonic development and embryonic genome activation events.     

Stimulations of strontium-doped calcium polyphosphate for bone tissue engineering to protein secretion and mRNA expression of the angiogenic growth factors from endothelial cells in vitro

The vascularization of tissue-engineered bone is the key problem needed solving before application of tissue-engineered bone in clinical practice. Meanwhile, endothelial cells are the major and important source of seed cells in bone tissue engineering, and significant on promoting vascularization in tissue-engineered bone. Vascularization (namely angiogenesis) is a process mainly controlled by several angiogenic growth factors (VEGF, bFGF and MMP-2) which can be secreted by endothelial cells. Therefore, the research on the stimulations of SCPP to the secretion of the angiogenic growth factors from endothelial cells is very important. This study was performed to determine the ability of strontium-doped calcium polyphosphate (SCPP) to induce angiogenesis by detecting the protein secretion levels and mRNA expression of VEGF, bFGF and MMP-2 from cultured endothelial cells. As a control, we also researched the effect of HA on the mRNA expressions and protein secretion of angiogenic growth factors from cultured endothelial cells. We cultured endothelial cells with SCPP scaffolds containing various concentration of strontium and HA. The results obtained in the MTT and SEM tests indicated that endothelial cells on SCPP scaffold exhibited higher proliferation rate and were easy to get a good spread than them on CPP, the best state of growth and proliferation of cells could be observed on 8%SCPP. The results of ELISA demonstrated that the protein levels of VEGF, bFGF and MMP-2 from cultured endothelial cells increased with the increasing Sr doped in calcium polyphosphate in SCPP groups, the peaks appeared on 8%SCPP. All SCPP groups showed a better ability to stimulate the protein secretion of VEGF, bFGF and MMP-2 from endothelial cells relative to CPP group and HA group. The results of RT-PCR suggested that the 8%SCPP group exhibited a significantly higher mRNA expression of VEGF, bFGF and MMP-2 relative to CPP group and HA group. In conclusion, the results of this study demonstrated that 8%SCPP had obvious promotion for secretion and mRNA expression of angiogenic growth factors from cultured endothelial cells.     

Bioconversion of hydrocortisone to prednisolone by immobilized bacterial cells in a two-liquid-phase system

Bioconversion of hydrocortisone to prednisolone by free, immobilized and reused immobilized cells of three bacterial strains (Bacillus sphaericus ATCC 13805, Bacillus sphaericus SRP III and Arthrobacter simplex 6946) in an aqueous and a two-liquid-phase system using different organic solvents was investigated. The experiments were carried out in a 125 cm³ shake flask at 27±2°C, 220 rpm for 96 h. The contents of prednisolone and hydrocortisone in samples taken at 0, 3, 6, 24, 48, 72, 96 and 144 h were determined by HPLC analysis. The immobilized bacterial cells showed higher prednisolone yield than the free form in an aqueous system. In the two-phase systems, the butyl acetate to aqueous media ratio of 1: 30 for all three bacterial strains in immobilized forms gave the highest prednisolone yields, at an incubation time of 144 h, of 87·6, 70·6 and 88·3% respectively. For an n-decane to aqueous ratio of 1: 6, moderate prednisolone yields of 81·8, 47·9 and 71·4% were obtained with shorter incubation times of 72, 96 and 6 h respectively. For cyclohexane and other alcohols, the organisms produced low yields of prednisolone (0–30%). Single reuse of all three immobilized bacterial cells gave a 3–20% lower yield of prednisolone than the non-reused cells. The increase in hydrocortisone concentration decreased the prednisolone production whereas increasing the n-decane to aqueous ratio from 1: 6 to 1: 3 caused no significant change in the productivity. © 1998 Society of Chemical Industry     

Use of engineered Escherichia coli cells to detect estrogenicity in everyday consumer products

BACKGROUND: Estrogenic activity has been observed in several industrial and household products, and some evidence suggests that this activity may be linked to increased pathologies in humans and animals. Here, an engineered strain of Escherichia coli is evaluated for its ability to detect estrogenic activity in complex mixtures, including natural dietary supplements, hand and body washes, essential oils, and perfumes. The engineered E. coli biosensor strain expresses the ligand‐binding domain of the human estrogen receptor β (ERβ) as part of a larger allosteric reporter enzyme. The result is a simple bacterial growth assay, where estrogenic activity of a test compound is reflected by increased cell growth on a simple defined medium. RESULTS: While most consumer products did not yield a strong estrogenic response in the assay, a consistent estrogenic effect was observed with several perfumes. This effect is probably due to the presence of the known estrogen, benzophenone‐2, which exhibited an EC₅₀ concentration of 0.44 µmol L^?1 for the sensor strains used. CONCLUSIONS: This simple, bacterial biosensor is capable of rapidly and inexpensively detecting estrogenic activity in complex consumer products, and may eventually yield rough estimates of the equivalent estrogen doses associated with their use. Copyright © 2009 Society of Chemical Industry     

Teaching chemical engineering to biotechnology students in the time of COVID-19: Assessment of the adaptation to digitalization

With the global outbreak of COVID-19 in March 2020, there was an immediate shutdown of face-to-face classes and a sudden shift to on-line learning. Confinement required finding innovative approaches to teaching and student assessment. This paper aims to share the experience of adapting the course in Biochemical Engineering, part of the Biotechnology program at Francisco de Vitoria University (Madrid, Spain), to remote learning.A sequence of collaborative learning activities, with active student participation, was designed to replace the traditional mid-term exam. Activities were carefully implemented, considering the range of learning styles. Engineering skills, transversal competences and higher-order thinking skills were fostered through these activities.The analysis of the teaching/learning experience was based on teacher observations, academic performance and student surveys. All indicators showed that the adopted methodology had a positive impact of student performance. Student participation, especially among those repeating the course, also improved. Furthermore, students gained a more accurate and positive perception of the link between Chemical Engineering and Biotechnology, which may have a favourable impact on the teaching of Bioreactors in the coming academic year.     

The life and death of gc: The changeover to si and the declining use of gc in chemical engineering textbooks

Thirty years ago, an editorial on metrology in the March 1971 issue of AlChE Journal noted the following: “Recognizing the inevitable, the AlChE Journal will require that all papers submitted after July 1, 1971 conform in notation to the SI System (Système International d'Unités)”. This decision was the starting point for the gradual introduction of the use of the SI System in chemical engineering textbooks, at a substitute for the preceding British System. As a consequence, the use of the g_c conversion factor has been also diminishing, gradually but at a slower pace In this paper, the changeover to SI and the declining use of g_c in chemical engineering textbooks is analyzed. Firstly, some representative books published before 1971 are studied. Secondly, a special analysis is devoted to transport phenomena books. Finally, a few but significant books published since 1971, have been selected in order to carry out the analysis of the changeover to SI System and the evolution of the use of g_c     

化学工程在低碳发展转型中的关键作用探讨——从物质资源利用与碳排放关联的视角

当前物质资源利用模式迫切需要向低碳发展转型。化学工程的科研人员及流程工业领域的利益相关者,有必要以资源利用模式的系统视角,重新审视物质资源利用与碳排放的复杂关系。基于本研究团队近年来对资源效率模式及低碳转型的研究成果,结合国内外相关研究进展,针对化学工程与低碳转型发展的关系进行深入分析,总结提出三个主要观点：（1）低碳转型中提升资源效率与碳减排存在正向协同,即物质资源利用与碳排放存在强关联,需要提升资源效率促进低碳发展转型;（2）低碳转型中碳减排和物质资源利用存在反向协同,低碳转型将拉动大量物质资源需求,需要通过技术创新和发展循环经济来对冲;（3）气候目标下化石资源利用模式将发生深刻变革,化石资源将更多地发挥“材料属性”而不是“能源属性”;“可持续的能源”和“可持续的碳源”将成为低碳流程工业的未来发展方向。化学工程作为研究物质资源转化的核心学科,将在人类向低碳社会过渡中发挥重要的和不可替代的作用。     

The dynamic response of PEM fuel cells to changes in load

The dynamic response of the stirred tank reactor (STR) polymer electrolyte membrane (PEM) fuel cell has been explored over the temperature range of 35-. When the fuel cell was operated in the autohumidification mode the fuel cell current “ignited’’ when the membrane water content was greater than a critical level of ∼1.6 H₂O/SO₃, and it extinguished when the initial membrane water content was below this critical level. Above , two stable “ignited’’ states were observed at intermediate load resistances; these steady states corresponded to different levels of membrane hydration. At low load resistances only a single ignited steady state was observed with high membrane hydration, and at high load resistances only a single ignited steady state was observed with intermediate membrane hydration. Hysteresis between the two ignited states was observed; the steady state selected depended on the initial conditions in the fuel cell. The time constant for the fuel cell current to reach steady state after a change in the load resistance was ∼10³-. Below only one “ignited’’ state and the extinguished state were observed in the autohumidification fuel cell. After 3000 h of operation the STR PEM fuel cell current and effluent relative humidities oscillated autonomously between two membrane hydration states with a period of oscillation of ∼10,000 s. The oscillations showed abrupt transitions indicative of a capacitive switch. These complex dynamics of PEM fuel cell operation are associated with the membrane water uptake. It is hypothesized that water produced and swells the membrane, altering the interfacial membrane-electrode contact.     

Recent progress in the green synthesis of rare-earth doped upconversion nanophosphors for optical bioimaging from cells to animals

Rare-earth doped upconversion nanophosphors (UCNPs), which convert low energy near-infrared (NIR) photons into high energy photons such as ultraviolet, visible light and NIR light, have found various applications in optical bioimaging. In this review article, we summarize recent advances in the synthesis and applications of UCNPs achieved by us and other groups in the past few years. The approaches for the synthesis of UCNPs are presented, with an emphasis on the role of green chemistry in the advancement of this field, followed by a focused overview on their latest applications in optical bioimaging from subcellular structures through cells to living animals. Challenges and opportunities for the use of UCNPs in biomedical diagnosis and therapy are discussed.     

Imaging of selective nuclear receptor modulator-induced conformational changes in the nuclear receptor to allow interaction with coactivator and corepressor proteins in living cells

Selective nuclear receptor modulators (SNRMs), which are used clinically for the treatment of NR-related diseases, display mixed agonistic/antagonistic activity in a tissue-selective manner depending on the cellular concentrations of coregulator proteins, that is, coactivators and corepressors. The molecular details of the SNRM function provided us with an idea for a rational method for the high-throughput screening of SNRMs in real time in intact living cells. We have developed genetically encoded fluorescent indicators based on the principle of ligand-induced coactivator and/or corepressor recruitment to NR ligand binding domain in single living cells. We demonstrated that an SNRM induces a distinct conformational change in the NR LBD, which is different from that induced by a full agonist or antagonist, but favorable for the recruitment of a coactivator or corepressor protein to the NR. The molecular details of an SNRM binding to a NR, and the subsequently induced conformational changes and recruitment of coregulator protein(s) are important features for the understanding of SNRM action in the living body. Our fluorescent indicators are capable of distinguishing among agonists, antagonists, and SNRMs, and can therefore serve as versatile molecular sensors that predict the pharmacological character of ligands, which is important for an accurate cure of a disease.