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1.
J Opt Soc Am A Opt Image Sci Vis ; 41(6): 1122-1127, 2024 Jun 01.
Article in English | MEDLINE | ID: mdl-38856426

ABSTRACT

Synthetic dimensions have drawn intense recent attention in investigating higher-dimensional topological physics and offering additional degrees of freedom for manipulating light. It has been demonstrated that synthetic dimensions can help to concentrate light with different frequencies at different locations. Here, we show that synthetic dimensions can also route light from different incident directions. Our system consists of an interface formed by two different photonic crystals. A synthetic dimension ξ is introduced by shifting the termination position of the photonic crystal on the right-hand side of the interface. We identify a correspondence between ξ and the interface state such that light incident from a specific direction can be collected. Thus, routing incident light from different directions is achieved by designing an interface with a proper distribution of ξ. Traditionally, this goal is achieved with a standard 4f optical system using a convex lens, and our approach offers the possibility for such a capability within a few lattice sites of photonic crystals. Such an approach reduces the size of the system, making it easier for integration. Our work provides, to our knowledge, a new direction for routing light with different momentums and possibly contributes to applications such as lidar.

2.
BMC Genomics ; 24(1): 754, 2023 Dec 07.
Article in English | MEDLINE | ID: mdl-38062379

ABSTRACT

Bergenia purpurascens is an important medicinal, edible and ornamental plant. It generally grows in high-altitude areas with complex climates. There have been no reports about how B. purpurascens survives under cold stress. Here, the B. purpurascens under low temperature were subjected to transcriptomics analysis to explore the candidate genes and pathways that involved in the cold tolerance of B. purpurascens. Compared with the control treatment, we found 9,600 up-regulated differentially expressed genes (DEGs) and 7,055 down-regulated DEGs. A significant number of DEGs were involved in the Ca2+ signaling pathway, mitogen-activated protein kinase (MAPK) cascade, plant hormone signaling pathway, and lipid metabolism. A total of 400 transcription factors were found to respond to cold stress, most of which belonged to the MYB and AP2/ERF families. Five novel genes were found to be potential candidate genes involved in the cold tolerance of B. purpurascens. The study provide insights into further investigation of the molecular mechanism of how B. purpurascens survives under cold stress.


Subject(s)
Cold-Shock Response , Gene Expression Regulation, Plant , Humans , Cold-Shock Response/genetics , Gene Expression Profiling , MAP Kinase Signaling System , Signal Transduction , Cold Temperature , Transcriptome
3.
Langmuir ; 39(39): 13986-13999, 2023 Oct 03.
Article in English | MEDLINE | ID: mdl-37725795

ABSTRACT

To solve the adhesion problem between molten aluminum and vacuum ladle liner during the electrolytic aluminum production process, the wetting state and adhesion properties of molten aluminum droplets on substrate surfaces with different nanopillars are investigated based on molecular dynamics. The results show that the adhesion strength of molten aluminum droplets in different wetting states has the pattern Young state > Wenzel state > Cassie state. Effects of increasing nanopillar height or interval are poles apart in the wetting state and adhesion characteristics of aluminum molten droplets. The critical height and critical interval of the nanopillar where the wetting state transition occurs are obtained. The increase of the nanopillar width can induce the wetting state transition from the Cassie state to the Wenzel state. In addition, the phantom wall method is applied to study the variation of the separation force. It is found that a peak in the separation force curve occurs when the molten droplet separates from the bottom of the nanopillar interval or the top of the nanopillar. The separation force curves of the droplets in the Young state and the Cassie state have single peaks, while the droplets in the Wenzel state have double peaks.

4.
Langmuir ; 38(2): 743-750, 2022 Jan 18.
Article in English | MEDLINE | ID: mdl-34989574

ABSTRACT

Over the last three decades, research on redox-active monolayers has consolidated their importance as advanced functional material. For widespread monolayer systems, such as alkanethiols on gold, non-ideal multiple peaks in cyclic voltammetry are generally taken as indication of heterogeneous intermolecular interactions─namely, disorder in the monolayer. Our findings show that, contrary to metals, peak multiplicity of silicon photoelectrodes is not diagnostic of heterogeneous intermolecular microenvironments but is more likely caused by photocurrent being heterogeneous across the monolayer. This work is an important step toward understanding the cause of electrochemical non-idealities in semiconductor electrodes so that these can be prevented and the redox behavior of molecular monolayers, as photocatalytic systems, can be optimized.

5.
Sheng Li Xue Bao ; 74(4): 657-668, 2022 Aug 25.
Article in Zh | MEDLINE | ID: mdl-35993217

ABSTRACT

Neural oscillations reflect synchronized activities of neuronal ensembles in central nervous system. In the hippocampus, thalamus, neocortex and other brain subregions, neural oscillation can be detected and plays a crucial role in many complicated cognitive processes. Decoupling and damaging of neural oscillation play a key role in the induction of severe cognition deficits in many psychiatric disorders. In this review, we summarize research advances in the underlying mechanisms and physiological functions of neural oscillations. We also discuss the abnormal changes of sharp wave-ripple, gamma oscillation and sleep spindle oscillation in major depressive disorder, schizophrenia and Alzheimer's disease, etc. Finally, the application potential of neural oscillations as clinical diagnosis and treatment targets is evaluated and prospected.


Subject(s)
Depressive Disorder, Major , Hippocampus/physiology , Humans , Neurons , Sleep/physiology
6.
Sichuan Da Xue Xue Bao Yi Xue Ban ; 53(6): 1007-1011, 2022 Nov.
Article in Zh | MEDLINE | ID: mdl-36443043

ABSTRACT

Hypertensive disorder in pregnancy is a disease with diverse clinical manifestations. Herein, we provided interpretations for "The Guidelines for the Diagnosis and Treatment of Hypertensive Disorders in Pregnancy in China (2020 Edition)" and discussed the difficulties and confusion encountered in the management of hypertensive disorders in pregnancy in combination with clinical practice. Lowering blood pressure is the most important treatment and maintaining a stable target blood pressure can reduce damage to organ functions and is beneficial to fetal growth. When applying magnesium sulfate, attention should be paid to the indications and contraindications. Attention should be paid to hypoproteinemia in patients tested positive for proteinuria. There should be dynamic evaluation of the functions of maternal vital organs, fetal growth and development, fetal well-being and intrauterine safety, and determination of the appropriate timing of the termination of pregnancy, so as to ensure maternal and fetal safety. Attention should be paid to maternal high-risk factors, if early prediction and prevention are to be accomplished in order to reduce the incidence and severity of the disease.


Subject(s)
Hypertension, Pregnancy-Induced , Female , Pregnancy , Humans , Hypertension, Pregnancy-Induced/diagnosis , Hypertension, Pregnancy-Induced/drug therapy , Fetus , China , Family , Prenatal Care
7.
Zhongguo Zhong Yao Za Zhi ; 47(11): 3095-3104, 2022 Jun.
Article in Zh | MEDLINE | ID: mdl-35718534

ABSTRACT

This study aims to summarize the research hotspots of Hedysari Radix and predict the research trend with bibliometric methods, which is expected to serve as a reference for future research. CiteSpace V 5.8.R2 was employed for visualization of the number, authors, author affiliations, journals, funds, and keywords of the Chinese and English articles on Hedysari Radix in China National Knowledge Infrastructure(CNKI) and Web of Science(WOS) from 2001 to 2021. A total of 693 Chinese articles and 167 English articles were finally included. According to the knowledge map, most of the articles were from China and the authors from China had a close cooperation with the related institutions in the United States and Australia. Gansu University of Chinese Medicine(288) and Lanzhou University(151) respectively came out on top of the author affiliations in the number of Chinese and English articles. The journals were mainly about Chinese medicine, mainly including Chinese Journal of Information on Traditional Chinese Medicine and Evidence-based Complementary and Alternative Medicine. Papers(191 in Chinese and 60 in English) funded by National Natural Science Foundation of China were the most. Keyword analysis suggested that the main research directions were pharmacological action and mechanism, component analysis, content determination, and industrialization of medicinal materials of Hedysari Radix and that the research hotspots were the prevention and treatment of diabetes and its complications, tumors, myocardial injury, liver fibrosis and other diseases with active components such as polysaccharides, ultrafiltrate, formononetin, and calycosin. The targets, signaling pathways, and genes related to the anti-tumor, heart protection, prevention and treatment of diabetes and its complications, and regulation of immunity should be further studied.


Subject(s)
Bibliometrics , Medicine, Chinese Traditional , China , Humans , Plant Roots , United States
8.
J Am Chem Soc ; 143(3): 1267-1272, 2021 Jan 27.
Article in English | MEDLINE | ID: mdl-33373229

ABSTRACT

The electrochemical reduction of bulk silica, due to its high electrical resistance, is of limited viability, namely, requiring temperatures in excess of 850 °C. By means of electrochemical and electrical measurements in atomic force microscopy, we demonstrate that at a buried interface, where silica has grown on highly conductive Si(110) crystal facets, the silica-silicon conversion becomes reversible at room temperature and accessible within a narrow potential window. We conclude that parasitic signals commonly observed in voltammograms of silicon electrodes originate from silica-silicon redox chemistry. While these findings do not remove the requirement of high temperature toward bulk silica electrochemical reduction, they redefine for silicon the potential window free from parasitic signals and, as such, significantly restrict the conditions where electroanalytical methods can be applied to the study of silicon surface reactivity.

9.
J Am Chem Soc ; 143(42): 17431-17440, 2021 10 27.
Article in English | MEDLINE | ID: mdl-34657417

ABSTRACT

Herein we demonstrate that ionic liquids can form long-lived double layers, generating electric fields detectable by straightforward open circuit potential (OCP) measurements. In imidazolium-based ionic liquids an external negative voltage pulse leads to an exceedingly stable near-surface dipolar layer, whose field manifests as long-lived (∼1-100 h) discrete plateaus in OCP versus time traces. These plateaus occur within an ionic liquid-specific and sharp potential window, defining a simple experimental method to probe the onset of interfacial ordering phenomena, such as overscreening and crowding. Molecular dynamics modeling reveals that the OCP arises from the alignment of the individual ion dipoles to the external electric field pulse, with the magnitude of the resulting OCP correlating with the product of the projected dipole moment of the cation and the ratio between the cation diffusion coefficient and its volume. Our findings also reveal that a stable overscreened structure is more likely to form if the interface is first forced through crowding, possibly accounting for the scattered literature data on relaxation kinetics of near-surface structures in ionic liquids.

10.
J Environ Manage ; 277: 111488, 2021 Jan 01.
Article in English | MEDLINE | ID: mdl-33070017

ABSTRACT

Soil wind erosion is an important ecological environmental problem that is widespread in arid and semi-arid regions. Currently, related studies are mainly focused on spatiotemporal characteristics or analysis of effector mechanisms, and they do not facilitate direct servicing of management decisions. In this paper, we used the Xilingol typical steppe in Inner Mongolia, China, as a study site to develop a decision framework for a comprehensive understanding of soil wind erosion and to promote sustainable management of steppes. In this study, we used the Revised Wind Erosion Equation model to simulate soil wind erosion. We combined this model with linear trend analysis to evaluate the ecological effects of soil wind erosion and wind erosion intensity, and delineated the gravity center migration path. We used the constraint line method to reveal the mechanisms by which climatic factors affected soil wind erosion, achieved the spatial visualization of wind-breaking and sand-fixing service flow, and proposed decision-based regional sustainable development suggestions. The results showed that long-term soil wind erosion will lead to soil coarsening and loss of soil nutrients. Soil wind erosion in the study site showed worsening trends and risks, and as such, ecological environment conservation and management are urgently required. The study framework promotes a clear understanding of the complex relationship of human-earth systems. The study results will aid in the ecological remediation of steppe landscapes and the prevention of desertification and will provide a foundation for win-win management of ecological conservation and economic development in arid and semi-arid regions.


Subject(s)
Soil , Wind , China , Conservation of Natural Resources , Desert Climate , Ecosystem , Humans
11.
BMC Urol ; 20(1): 182, 2020 Nov 10.
Article in English | MEDLINE | ID: mdl-33172469

ABSTRACT

BACKGROUND: Aggressive angiomyxoma (AA) is a rare tumor that typically occurs in the pelvis and perineum, most commonly in women of reproductive age. However, no para-ureteral AA has been reported according to the literature. Case presentation We herein describe the first case of para-ureteral AA. A 62-year-old male presented to our institute in March 2017 with a para-ureteral mass that was 15 mm in diameter incidentally. No symptom was observed and laboratory analysis was unremarkable. Magnetic resonance and computed tomography imaging showed a non-enhancing mass abutting the left ureter without causing obstruction. Laparoscopic resection of the mass was performed without injury to the ureter. Pathologic and immunohistochemical results were consistent with AA. Till now, no recurrence was noticed. CONCLUSIONS: We reported a rare case of para-ureteral AA, along with a literature review. Early diagnosis, proper surgical plan and long-term close follow-up is recommended for its high risk of recurrence and malignant potential.


Subject(s)
Myxoma/pathology , Ureteral Neoplasms/pathology , Humans , Incidental Findings , Male , Middle Aged
12.
Zhongguo Zhong Yao Za Zhi ; 45(5): 1180-1187, 2020 Mar.
Article in Zh | MEDLINE | ID: mdl-32237463

ABSTRACT

Based on the idea of plant metabolomics, ultra performance liquid chromatography-quadrupole time-of-flight mass spectrometry(UPLC-Q-TOF-MS/MS) was used to compare the chemical composition between 6 batches of fruit vinegar brewed from Choerospondias axillaris fruit peel and 6 batches of apple vinegar purchased from 3 companies. Antioxidant and α-glucosidase inhibition activities were also tested in vitro. A total of 43 compounds were identified by reference substance, liquid chromatography-mass spectrometry(LC-MS/MS) fragmentation information or literature data. A total of 40 compounds were identified in the C. axillaris fruit peel vinegar. A total of 16 compounds were identified in apple vinegar. There were 13 common ingredients including organic acids and esters such as citric acid, 2-isopropyl malic acid, and triethyl citrate. The results of partial leastsquares-discriminant analysis(PLS-DA) indicated that they had 33 significantly different compounds such as proanthocyanidin oligomer, quercetin-3-O-rhamnoside and heptadecanoic acid. The proanthocyanidins and flavonoid glycosides in C. axillaris peel vinegar were more abundant than apple vinegar, so it had better health function than ordinary fruit vinegar. The results showed that C. axillaris fruit peel vinegar had stronger antioxidant and α-glucosidase inhibition activities in vitro. The vinegar brewed from waste C. axillaris fruit peel had more chemical ingredients than the apple vinegar. C. axillaris fruit peel vinegar had better biological activity and health function, so it had good development prospect. This study provided the scientific evidence for exploiting the C. axillaris fruit peel into high value-added products. It also provided ideas for the comprehensive development and utilization of similar Chinese medicine waste.


Subject(s)
Acetic Acid/pharmacology , Anacardiaceae/chemistry , Glycoside Hydrolase Inhibitors/pharmacology , Malus/chemistry , Antioxidants , Chromatography, High Pressure Liquid , Fruit/chemistry , Plant Extracts , Tandem Mass Spectrometry , alpha-Glucosidases
14.
Zhongguo Zhong Yao Za Zhi ; 44(21): 4621-4626, 2019 Nov.
Article in Zh | MEDLINE | ID: mdl-31872656

ABSTRACT

In this study,a nano drug delivery system GA-DTX-NGO which could be used for liver tumor photothermal and chemotherapy was prepared and characterized,with docetaxel(DTX) as model drug,glycyrrhetinic acid(GA) as the target molecule,and nano graphene oxide(NGO) as the photosensitizer. Firstly,GA-NGO nanocomposites were synthesized by the amidation reaction,and then GA-DTX-NGO was prepared by ultrasonic dispersion method. The encapsulation efficiency and drug loading ratio were determined by high performance liquid chromatography(HPLC) and ultracentrifugation; the morphology was observed by transmission electron microscopy(TEM). The photothermal conversion test was carried out by laser irradiation at 808 nm and the drug release test in vitro was performed using reverse dialysis. Finally,the effect of GA-DTX-NGO on SMMC-7721 liver tumor cells proliferation was determined by using MTT assay. The results showed that GA-DTX-NGO had good water dispersibility,and TEM results showed a lamellar structure with about 200 nm in diameter. The encapsulation efficiency and drug loading ratio of GA-DTX-NGO were(98. 89 ± 0. 07) % and(64. 74±0. 26) %,respectively. GA-DTX-NGO had strong photothermal conversion performance under 808 nm of laser irradiation. The drug release test in vitro results showed GA-DTX-NGO had obvious sustained-release effects and temperature-dependent release characteristics. The results of cell assay showed that GA-DTX-NGO could effectively inhibit the proliferation of SMMC 7721 cells in a concentration-and time-dependent manner,and the inhibitory effect was enhanced after combination with the near-infrared therapy. In conclusion,the preparation process of GA-DTX-NGO nano drug delivery system is feasible,which could provide some theoretical basis for further study of photothermal and chemotherapy on liver tumor.


Subject(s)
Antineoplastic Agents , Drug Delivery Systems , Glycyrrhetinic Acid , Graphite , Drug Carriers
15.
Zhongguo Zhong Yao Za Zhi ; 44(10): 2078-2083, 2019 May.
Article in Zh | MEDLINE | ID: mdl-31355564

ABSTRACT

The traditional Chinese medicine standard decoction is prepared on the basis of the theory of traditional Chinese medicine and clinical application. With reference to the modern extraction method,the single decoction of traditional Chinese medicine is prepared by the standardized process,and the establishment of its quality standards is conducive to standardizing clinical medication. This research is to set an evaluation standard for the quality of salt-processed Psoraleae Fructus standard decoction. Twelve batches of salt-processed Psoraleae Fructus standard decoctions were prepared. The contents of psoralen and isopsoralen were determined,the transfer and extract rates were calculated,and the pH value was measured; HPLC fingerprint method was established for analysis. The results of the 12 batches of samples revealed that the transfer rates of psoralen and isopsoralen were 17. 10%-26. 40%,14. 70%-22. 70%,respectively; the extract rate was between 14. 7%-27. 0%,and the pH value was between 5. 4-6. 9. Moreover,7 common chromatographic peaks were determined based on fingerprint by using similarity evaluation system for chromatographic fingerprint of traditional Chinese medicine( 2012 A).The similarities of the 12 batches of samples were analyzed and compared,and the results showed that the similarities were all higher than0. 9. In this study,the preparation method for salt-processed Psoraleae Fructus decoction was standard,with high similarities in fingerprint. This study build a convenient and reliable method of comprehensive quality evaluation,with a high precision,stability and repeatability,which can provide a reference for the quality control of salt-processed Psoraleae Fructus dispensing granules.


Subject(s)
Drugs, Chinese Herbal/analysis , Fruit/chemistry , Psoralea/chemistry , Quality Control , Chromatography, High Pressure Liquid , Medicine, Chinese Traditional , Phytochemicals/analysis
16.
Sensors (Basel) ; 19(1)2018 Dec 21.
Article in English | MEDLINE | ID: mdl-30577676

ABSTRACT

Wireless sensor networks (WSNs) are an important type of network for sensing the environment and collecting information. It can be deployed in almost every type of environment in the real world, providing a reliable and low-cost solution for management. Huge amounts of data are produced from WSNs all the time, and it is significant to process and analyze data effectively to support intelligent decision and management. However, the new characteristics of sensor data, such as rapid growth and frequent updates, bring new challenges to the mining algorithms, especially given the time constraints for intelligent decision-making. In this work, an efficient incremental mining algorithm for discovering sequential pattern (novel incremental algorithm, NIA) is proposed, in order to enhance the efficiency of the whole mining process. First, a reasoned proof is given to demonstrate how to update the frequent sequences incrementally, and the mining space is greatly narrowed based on the proof. Second, an improvement is made on PrefixSpan, which is a classic sequential pattern mining algorithm with a high-complexity recursive process. The improved algorithm, named PrefixSpan+, utilizes a mapping structure to extend the prefixes to sequential patterns, making the mining step more efficient. Third, a fast support number-counting algorithm is presented to choose frequent sequences from the potential frequent sequences. A reticular tree is constructed to store all the potential frequent sequences according to subordinate relations between them, and then the support degree can be efficiently calculated without scanning the original database repeatedly. NIA is compared with various kinds of mining algorithms via intensive experiments on the real monitoring datasets, benchmarking datasets and synthetic datasets from aspects including time cost, sensitivity of factors, and space cost. The results show that NIA performs better than the existed methods.

17.
Zhongguo Zhong Yao Za Zhi ; 43(8): 1596-1601, 2018 Apr.
Article in Zh | MEDLINE | ID: mdl-29751705

ABSTRACT

The enzymatic browning is one of the main reasons for affecting the quality of medicinal flowers. In the process of chrysanthemum harvesting and processing, improper treatment will lead to the browning and severely impact the appearance and quality of chrysanthemum. Peroxidase enzyme is one of the oxidoreductases that cause enzymatic browning of fresh chrysanthemum. The enzymatic characteristics of peroxidase (POD) in chrysanthemum were studied in this paper. In this experiment, the effects of different reaction substrates and their concentrations, PH value of buffer and reaction temperatures on the activity of POD enzyme were investigated. The results showed that the optimal substrate of POD was guaiacol, and the optimal concentration of POD was 50 mmol·L⁻¹. The optimal pH value and reaction temperature were 4.4 and 30-35 °C, respectively. Michaelis-Menten equation was obtained to express the kinetics of enzyme-catalyzed reaction of POD, Km=0.193 mol·L⁻¹, Vmax=0.329 D·min⁻¹. In addition, the results of POD enzyme thermal stability test showed that the POD enzyme activity was inhibited when being treated at 80 °C for 4 min or at 100 °C for 2 min. The above results were of practical significance to reveal the enzymatic browning mechanism, control the enzymatic browning and improve the quality of chrysanthemum, and can also provide the basis for the harvesting and processing of medicinal materials containing polyphenols.


Subject(s)
Chrysanthemum , Flowers , Kinetics , Peroxidase , Temperature
18.
J Oral Maxillofac Surg ; 75(3): 641-647, 2017 Mar.
Article in English | MEDLINE | ID: mdl-27669373

ABSTRACT

PURPOSE: Relevant reports about oral candidiasis status and prevention measures after free flap surgery for the oral and maxillofacial region are limited. The present study explored oral candidiasis status after free flap surgery and its prevention through a prospective comparative study. PATIENTS AND METHODS: One hundred four patients were randomized to a control group (n = 54) and an experimental group (n = 50). Compared with the control group, the experimental group was provided an additional 3% sodium bicarbonate saline solution for oral care after free flap surgery. The incidence of oral candidiasis was evaluated by objective examination (saliva culture and salivary pH measurement) and subjective evaluation (clinical signs of oral candidiasis) at admission and from postoperative days 1 to 14. RESULTS: The salivary pH values of the 2 groups were lower than the normal salivary pH, and postoperative salivary pH values were always lower than the active range of oral lysozymes in the control group. The salivary pH values of the experimental group were higher than those of the control group from postoperative days 6 to 14 (P < .05). The incidence of oral candidiasis was 13.0% in the control group, which was higher than that in the experimental group (2.0%; P < .05). In addition, advanced age, use of a free flap for the simultaneous repair of intraoral and paraoral defects, and a combination of 2 antibiotic types were risk factors for oral candidiasis. CONCLUSION: Oral candidiasis was common in patients after free flap reconstruction surgery, and the use of 3% sodium bicarbonate saline solution for oral care effectively prevented it.


Subject(s)
Candidiasis, Oral/prevention & control , Free Tissue Flaps , Oral Surgical Procedures , Sodium Bicarbonate/administration & dosage , Administration, Oral , Candidiasis, Oral/epidemiology , Female , Humans , Hydrogen-Ion Concentration , Incidence , Male , Middle Aged , Prospective Studies , Saliva/microbiology
19.
Biomed Environ Sci ; 29(3): 224-8, 2016 Mar.
Article in English | MEDLINE | ID: mdl-27109134

ABSTRACT

The nonstructural protein 1 (NS1) of influenza A virus, which is absent from the viral particle, but highly expressed in infected cells, strongly antagonizes the interferon (IFN)-mediated antiviral response. We engineered an NS1-expressing 293 (293-NS1) cell line with no response to IFN stimulation. Compared with the parental 293 cells, the IFN-nonresponsive 293-NS1 cells improved the growth capacity of various viruses, but the introduction of NS1 barely enhanced the propagation of Tahyna virus, a negative-strand RNA virus. In particular, fastidious enteric adenovirus that replicates poorly in 293 cells may grow more efficiently in 293-NS1 cells; thus, IFN-nonresponsive 293-NS1 cells might be of great value in diagnostic laboratories for the cultivation and isolation of human enteric adenoviruses.


Subject(s)
Influenza A virus/physiology , Viral Nonstructural Proteins/metabolism , Virus Cultivation/methods , Virus Replication/physiology , Cell Line , Gene Expression Regulation , HEK293 Cells , Humans , Viral Nonstructural Proteins/genetics
20.
Biotechnol Lett ; 37(8): 1671-7, 2015 Aug.
Article in English | MEDLINE | ID: mdl-25851952

ABSTRACT

OBJECTIVE: To enzymatically synthesize aroma acetoin fatty acid esters, useful as flavor and fragrance ingredients in foods. RESULTS: Immobilized Candida antarctica lipase B (CALB), performed significantly better than lipases from Rhizopus niveus and Candida rugosa in carrying out the esterification of acetoin and fatty acids. C4-C12 straight chain fatty acids were suitable acyl donors and CALB had a strong preference for longer straight chains up to ten carbon atoms. Higher temperatures, 40-60 °C, and higher acetoin/fatty acid molar ratios favored the conversion. The maximum yield of acetoin octanoate obtained was (51 ± 1) % after 24 h reaction time in hexane with 0.25 M octanoic acid, 5:1 excess acetoin and an enzyme concentration of 6 g/mol fatty acid at 60 °C. The enzyme activity declined at a steady rate during reuse at 60 °C and after the 10th cycle, 65 % of initial activity was still be retained. CONCLUSION: This is the first report of acetoin fatty acid ester synthesis by biological method and CALB has been shown to be effective for the lipase-catalyzed esterification of acetion and C4-C12 straight chain fatty acids.


Subject(s)
Acetoin/metabolism , Enzymes, Immobilized/metabolism , Fatty Acids/metabolism , Flavoring Agents/metabolism , Fungal Proteins/metabolism , Lipase/metabolism , Temperature
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