14,664 results match your criteria two-step synthesis

Synthesis of Carbonato- and Doubly Oxido-Bridged Diruthenium(III,IV) Complex and Reactions with Cations.

Inorg Chem 2021 Jun 21. Epub 2021 Jun 21.

Department of Materials and Life Sciences, Faculty of Science and Technology, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554 Japan.

Doubly oxido-bridged transition metal moieties, {M(μ-O)}, play important roles as oxidation reaction centers in nature. This work features a diruthenium(III,IV) complex with a doubly oxido-bridged core {Ru(μ-O)} with a carbonato bridged between the two ruthenium centers, M[{Ru(ebpma)}(μ-O)(μ-OCO)](PF) (M[](PF); , ebpma; ethylbis(2-pyridymethyl)amine), and explores the interactions of this complex with cations (H and M). M[](PF) was formed via reactions of a singly oxido-bridged complex, [{RuCl(ebpma)}(μ-O)]PF(CH)CO, with MCO (M = K, Na) or with CO(), adjusted to around pH 12 with NaOH(aq. Read More

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Modular Synthesis of Alkenyl Sulfamates and β-Ketosulfonamides via Sulfur(VI) Fluoride Exchange (SuFEx) Click Chemistry and Photomediated 1,3-Rearrangement.

Org Lett 2021 Jun 20. Epub 2021 Jun 20.

Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States.

Herein, we report a synthesis of medicinally relevant β-ketosulfonamides via a photomediated 1,3-rearrangement of alkenyl sulfamates. This protocol tolerates a wide array of sensitive functional groups including alkenes, alkynes, and nitrogen-based heterocycles. Additionally, this work provides a general approach toward alkenyl sulfamates via a two-step Sulfur(VI) Fluoride Exchange (SuFEx) sequence capitalizing on SOF as a linchpin to efficiently couple readily available ketones and amines without a large excess of either partner. Read More

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A Floatable Piezo-Photocatalytic Platform Based on Semi-Embedded ZnO Nanowire Array for High-Performance Water Decontamination.

Nanomicro Lett 2019 Jan 24;11(1):11. Epub 2019 Jan 24.

Department of Mechanical Engineering, Michigan State University, 428 S. Shaw Lane, East Lansing, MI, 48823, USA.

Highlights: ZnO nanowires were securely immobilized onto a floatable photocatalytic platform, which had a uniform diameter (55 ± 5 nm) and length (1.5 ± 0.3 μm). Read More

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January 2019

Methanogenic archaea use a bacteria-like methyltransferase system to demethoxylate aromatic compounds.

ISME J 2021 Jun 18. Epub 2021 Jun 18.

Department of Microbiology, Institute for Water and Wetland Research, Radboud University, Nijmegen, The Netherlands.

Methane-generating archaea drive the final step in anaerobic organic compound mineralization and dictate the carbon flow of Earth's diverse anoxic ecosystems in the absence of inorganic electron acceptors. Although such Archaea were presumed to be restricted to life on simple compounds like hydrogen (H), acetate or methanol, an archaeon, Methermicoccus shengliensis, was recently found to convert methoxylated aromatic compounds to methane. Methoxylated aromatic compounds are important components of lignin and coal, and are present in most subsurface sediments. Read More

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A Convolutional Neural Network for Improved Anomaly-Based Network Intrusion Detection.

Big Data 2021 Jun;9(3):233-252

Department of Computer Science, College of Computer and Information Sciences, King Saud University, Riyadh Saudi Arabia.

Cybersecurity protects and recovers computer systems and networks from cyber attacks. The importance of cybersecurity is growing commensurately with people's increasing reliance on technology. An anomaly detection-based network intrusion detection system is essential to any security framework within a computer network. Read More

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Sequential Continuous-Flow Synthesis of 3-Aryl Benzofuranones.

Chem Asian J 2021 Jun 17. Epub 2021 Jun 17.

Department of Chemistry, School of Science, The University of Tokyo, Hongo, 113-0033, Bunkyo-ku, Tokyo, Japan.

A sequential continuous-flow system to produce 3-aryl benzofuranones was developed. Starting from 2,4-di-tert-butylphenol and glyoxylic acid monohydrate, both the initial cyclocondensation and the subsequent Friedel-Crafts alkylation were catalyzed by the same heterogeneous catalyst, Amberlyst-15H. The catalyst has a promising life-time for these two steps, and it was able to be recovered and reused for several runs without deactivation. Read More

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Synthesis of L-[5-11C]Leucine and L-alfa-[5-11C]Methylleucine via Pd0-mediated 11C-Methylation and Microfluidic Hydrogenation: Potentiality of Leucine PET Probes for Tumor Imaging.

ChemMedChem 2021 Jun 14. Epub 2021 Jun 14.

RIKEN Kobe Institute, Center for Biosystems Dynamics Research, 6-7-3 Minatojima-minamimachi, Chuo-ku, 650-0047, Kobe, JAPAN.

The efficient synthesis of L-[5-11C]leucine and L-alfa-[5-11C]methylleucine has been investigated using a continuous two-step sequence of rapid reactions consisting of Pd0-mediated 11C-methylation and microfluidic hydrogenation. The synthesis of L-[5-11C]leucine and L-alfa-[5-11C]methylleucine was accomplished within 40 min with a decay-corrected radiochemical yield of 15-38% based on [11C]CH3I, radiochemical purity of 95-99%, and chemical purity of 95-99%. The Pd impurities in the injectable solution measured using inductively coupled plasma mass spectrometry met the international criteria for human use. Read More

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Synthesis of SPIO Nanoparticles and the Subsequent Applications in Stem Cell Labeling for Parkinson's Disease.

Nanoscale Res Lett 2021 Jun 14;16(1):107. Epub 2021 Jun 14.

Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, No. 88 Keling Road, Suzhou New District, Suzhou, 215163, China.

Parkinson's disease (PD) is characterized by the progressive loss of dopaminergic neurons in the midbrain, and the stem cell transplantation method provides a promising strategy for the treatment. In these studies, tracking the biological behaviors of the transplanted cells in vivo is essential for a basic understanding of stem cell function and evaluation of clinical effectiveness. In the present study, we developed a novel ultrasmall superparamagnetic iron oxide nanoparticles coating with the polyacrylic acid (PAA) and methoxypolyethylene glycol amine (PEG) by thermal decomposition method and a two-step modification. Read More

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A multicomponent tetrazolo indole synthesis.

Chem Commun (Camb) 2021 Jun 15. Epub 2021 Jun 15.

University of Groningen, Department of Pharmacy, Drug Design group, Groningen, The Netherlands.

The ubiquitous presence of the indole fragment in natural products and drugs asks for ever novel syntheses. We report an unprecedented mild, two-step synthesis of 2-tetrazolo substituted indoles based on the Ugi-tetrazole reaction combined with an acidic ring closure. A gram-scale synthesis, a bioactive compound and further transformations were performed. Read More

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Thiophene-fused polyaromatics: synthesis, columnar liquid crystal, fluorescence and electrochemical properties.

Chem Sci 2020 Apr 24;11(18):4695-4701. Epub 2020 Apr 24.

Department of Chemistry, Massachusetts Institute of Technology 77 Massachusetts Ave Cambridge MA 02143 USA

Efficient syntheses that incorporate thiophene units into different extended conjugation systems are of interest as a result of the prevalence of sulfur-rich aromatics in organic electronics. Self-organization by using liquid crystal properties is also desirable for optimal processing of organic electronics and optical devices. In this article, we describe a two-step process to access extended regioisomers of polyaromatics with different shapes. Read More

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In silico identification of novel chemical compounds with antituberculosis activity for the inhibition of InhA and EthR proteins from Mycobacterium tuberculosis.

J Clin Tuberc Other Mycobact Dis 2021 Aug 26;24:100246. Epub 2021 May 26.

Department of Biochemistry and Molecular Biology, Jahangirnagar University, Savar, Dhaka 1342, Bangladesh.

Tuberculosis (TB) continuously poses a major public health concern around the globe, with a mounting death toll of approximately 1.4 million in 2019. Reduced bioavailability, elevated toxicity, increased side effects, and resistance of multiple first-line and second-line TB medications, including isoniazid, ethionamide necessitate studies of new drugs. Read More

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A practical catalytic reductive amination of carboxylic acids.

Chem Sci 2020 Aug 12;11(35):9494-9500. Epub 2020 Aug 12.

School of Chemistry, GlaxoSmithKline Carbon Neutral Laboratories for Sustainable Chemistry, University of Nottingham 6 Triumph Road Nottingham NG7 2GA UK

We report reductive alkylation reactions of amines using carboxylic acids as nominal electrophiles. The two-step reaction exploits the dual reactivity of phenylsilane and involves a silane-mediated amidation followed by a Zn(OAc)-catalyzed amide reduction. The reaction is applicable to a wide range of amines and carboxylic acids and has been demonstrated on a large scale (305 mmol of amine). Read More

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Synthesis and Evaluation of F-Labeled Fluoroalkyl Triphenylphosphonium Salts as Mitochondrial Voltage Sensors in PET Myocardial Imaging.

Methods Mol Biol 2021 ;2275:49-64

Innovation Center for Molecular Probe Development, Department of Nuclear Medicine, Chonnam National University Medical School and Hwasun Hospital, Hwasun, South Korea.

We have previously reported that radiolabeled phosphonium cations accumulate in the mitochondria down a transmembrane potential gradient. We present an optimized procedure for synthesis of three [F]-labeled fluoroalkyl triphenylphosphonium salts ([F]FATPs) via two-step simple nucleophilic substitution reactions to develop new myocardial imaging agents for positron emission tomography (PET) . The total reaction time of [F]FATPs was within 60 min, and the overall decay-corrected radiochemical yield was approximately 15-30% (decay corrected). Read More

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January 2021

Synthesis and Formation Mechanism of Colloidal Janus-Type CuS/CuInS Heteronanorods Seeded Injection.

ACS Nano 2021 Jun 10. Epub 2021 Jun 10.

Condensed Matter and Interfaces, Debye Institute for Nanomaterials Science, Utrecht University, 3508 TA Utrecht, The Netherlands.

Colloidal heteronanocrystals allow for the synergistic combination of properties of different materials. For example, spatial separation of the photogenerated electron and hole can be achieved by coupling different semiconductors with suitable band offsets in one single nanocrystal, which is beneficial for improving the efficiency of photocatalysts and photovoltaic devices. From this perspective, axially segmented semiconductor heteronanorods with a type-II band alignment are particularly attractive since they ensure the accessibility of both photogenerated charge carriers. Read More

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Recirculating used cooking oil and Nagkesar seed shells in dual-stage catalytic biodiesel synthesis with C-C alcohols.

Environ Sci Pollut Res Int 2021 Jun 9. Epub 2021 Jun 9.

Department of Chemical Engineering, National Institute of Technology, M.G. Avenue, Durgapur, West Bengal, 713209, India.

The presented study discusses biodiesel synthesis by utilizing two wastes: Mesua ferrea Linn (MFL) seed shells (inert support for developing catalysts) and used cooking oil (feedstock). The MFL shells were used for heterogeneous acid and base catalyst development through carbonization, steam activation and subsequent doping of HSO or KOH, which upon instrumental examination showed effective doping of functional groups on the MFL char. The conversion approach uses methanol with sulfonated char (SC) for esterification, while the second stage utilizes 2-propanol for transesterification with KOH-doped char (KC) as a catalyst. Read More

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Vitamin D Status in Patients with Atrial Fibrillation and Heart Failure - Is there a Link?

Clin Lab 2021 Jun;67(6)

Background: The disturbed pleiotropic functions of vitamin D are related to numerous chronic non-skeletal diseases. The role of vitamin D insufficiency/deficiency in cardiovascular diseases (CVD) is controversial. Therefore, the aim was to study the vitamin D status in CVD patients and to reveal possible relationships with CVD risk factors. Read More

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Differential insulin sensitivity of NMR-based metabolomic measures in a two-step hyperinsulinemic euglycemic clamp study.

Metabolomics 2021 Jun 9;17(6):57. Epub 2021 Jun 9.

Section of Gerontology and Geriatrics; Department of Internal Medicine, Leiden University Medical Center, PO Box 9600, 2300RC, Leiden, The Netherlands.

Background: Insulin is the key regulator of glucose metabolism, but it is difficult to dissect direct insulin from glucose-induced effects. We aimed to investigate the effects of hyperinsulemia on metabolomic measures under euglycemic conditions in nondiabetic participants.

Methods: We assessed concentrations of 151 metabolomic measures throughout a two-step hyperinsulinemic euglycemic clamp procedure. Read More

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Acid-catalyzed oxidative cross-coupling of acridans with silyl diazoenolates and a Rh-catalyzed rearrangement: two-step synthesis of γ-(9-acridanylidene)-β-keto esters.

Org Biomol Chem 2021 Jun 9. Epub 2021 Jun 9.

School of Chemistry, Sun Yat-Sen University, Guangzhou 510006, China.

A MsOH-catalyzed oxidative cross-coupling of acridans and silyl diazoenolates and a Rh2(OAc)4-catalyzed rearrangement of the resultant diazo products are described. The reactions provide various γ-(9-acridanylidene)-β-keto esters in good yields, which bear an active α-methylene unit for further functionalization. Read More

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Tumor metabolism and associated serum metabolites define prognostic subtypes of Asian hepatocellular carcinoma.

Sci Rep 2021 Jun 8;11(1):12097. Epub 2021 Jun 8.

Laboratory of Human Carcinogenesis, Center for Cancer Research, National Cancer Institute, Bethesda, MD, 20892, USA.

Treatment effectiveness in hepatocellular carcinoma (HCC) depends on early detection and precision-medicine-based patient stratification for targeted therapies. However, the lack of robust biomarkers, particularly a non-invasive diagnostic tool, precludes significant improvement of clinical outcomes for HCC patients. Serum metabolites are one of the best non-invasive means for determining patient prognosis, as they are stable end-products of biochemical processes in human body. Read More

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Fluorescence "turn-on" Probe for Al3+ Detection in Water Based on ZnS/ZnO Quantum Dots with Excellent Selectivity and Stability.

Nanotechnology 2021 Jun 8. Epub 2021 Jun 8.

School of Material and Energy, Yunnan University, Cuihua North Road 2, Kunming, Yunnan, 650504, CHINA.

Herein, an efficient and stable fluorescent probe for Al3+ is established. The fluorescent probe bases on the fluorescent "turn on" mode of zinc sulfide crystal composite zinc oxide quantum dots (ZnS/ZnO QDs). The ZnS/ZnO QDs are synthesized via two-step method using L-Cysteine (L-Cys) as a sulfur source and stabilizer. Read More

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Atomically precise graphene nanoribbons: interplay of structural and electronic properties.

Chem Soc Rev 2021 Jun;50(11):6541-6568

Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747AG, Groningen, The Netherlands.

Graphene nanoribbons hold great promise for future applications in nanoelectronic devices, as they may combine the excellent electronic properties of graphene with the opening of an electronic band gap - not present in graphene but required for transistor applications. With a two-step on-surface synthesis process, graphene nanoribbons can be fabricated with atomic precision, allowing precise control over width and edge structure. Meanwhile, a decade of research has resulted in a plethora of graphene nanoribbons having various structural and electronic properties. Read More

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From reactive carbenes to chiral polyether macrocycles in two steps - synthesis and applications made easy?

Chem Sci 2020 Mar 12;11(25):6362-6369. Epub 2020 Mar 12.

Department of Organic Chemistry, University of Geneva Quai Ernest Ansermet 30 1211 Geneva 4 Switzerland

Chiral polyether macrocycles are versatile molecules. For their preparation, original two-step procedures were recently developed and present the advantages of high concentration conditions and simple starting reagents (stable diazo reagents, small cyclic ethers, aliphatic or aromatic amines). Enantiopure materials are readily afforded by CSP-HPLC on a semi-preparative scale. Read More

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One-Step Synthesis of 4-Octyl Itaconate through the Structure Control of Lipase.

J Org Chem 2021 Jun 4;86(12):7895-7903. Epub 2021 Jun 4.

Beijing Bioprocess Key Laboratory and State Key Laboratory of Chemical Resource Engineering, College of Life Science and Technology, Beijing University of Chemical Technology (BUCT), Beijing 100029, P. R. China.

4-Octyl itaconate is a novel antiviral and immunoregulatory small molecule showing great potential in the treatment of various autoimmune diseases and viral infections. It is difficult to selectively esterify the C4 carboxyl group of itaconate acid via one-step direct esterification using chemical catalysts, while the two-step route with itaconic anhydride as an intermediate is environmentally unfriendly and costly. This research investigated the one-step and green synthesis of 4-octyl itaconate through the structure control of lipase, obtaining 4-octyl itaconate with over 98% yield and over 99% selectivity. Read More

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Dual Regulation of Cytoplasm and Peroxisomes for Improved Α-Farnesene Production in Recombinant .

ACS Synth Biol 2021 06 3;10(6):1563-1573. Epub 2021 Jun 3.

The Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800# Lihu Road, WuXi 214122, People's Republic of China.

Microbial production of α-farnesene from renewable raw materials is a feasible alternative to traditional petroleum craft. Recently, the research on improving α-farnesene production in mainly focused on cytoplasmic engineering, while comprehensive engineering of multiple subcellular compartments is rarely reported. Here, we first sought to confirm that the isopentenol utilization pathway (IUP) could act as a two-step shortcut for IPP synthesis in peroxisomes. Read More

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(2-Fluoroallyl)pyridinium tetrafluoroborates: novel fluorinated electrophiles for Pd-catalyzed allylic substitution.

Org Biomol Chem 2021 Jun;19(21):4678-4684

N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky prosp., 119991 Moscow, Russian Federation.

An efficient two-step approach to 2-fluoroallyl amines was developed that involves the synthesis of (2-fluoroallyl)pyridinium tetrafluoroborates from readily available gem-bromofluorocyclopropanes and the application of the former as novel and stable 2-fluoroallyl electrophiles for Pd-catalyzed allylic substitution. Read More

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Rapid and mild synthesis of Au-NHC complexes in a simple two-phase flow reactor.

Dalton Trans 2021 Jun;50(23):7969-7975

Department of Chemistry, NTNU, NO-7491 Trondheim, Norway.

We describe a simple two-phase flow reactor which allows for the rapid synthesis of several Au(i)-NHC complexes in high yields (>88%), under mild conditions, and with minimal workup. Translation of the standard weak base method to a two-phase flow reaction prevents the common problem of decomposition to Au(0). The reaction can be scaled up more than ten-fold without loss in conversion efficiency. Read More

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Mesoporous silica nanoparticles with manganese and lanthanide salts: synthesis, characterization and cytotoxicity studies.

Dalton Trans 2021 Jun 2. Epub 2021 Jun 2.

LAQV-REQUIMTE, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Campus da Caparica, 2829-516 Caparica, Portugal.

Several organic salts based on the combination of two different choline derivative cations and MnCl3-, GdCl4- and TbCl4- as anions were immobilized in mesoporous silica nanoparticles (MSNs) by a two-step synthetic method. Firstly, MSNs were functionalized with choline derivative cations with chloride anions and then the metals were incorporated by the reaction of the chloride with the respective metal chloride salts. These nanomaterials were fully characterized by different characterization techniques such as 1H-NMR, FT-IR, elemental analysis, TEM, TGA, N2 adsorption, XRD and DLS. Read More

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Effects of early extubation followed by noninvasive ventilation versus standard extubation on the duration of invasive mechanical ventilation in hypoxemic non-hypercapnic patients: a systematic review and individual patient data meta-analysis of randomized controlled trials.

Crit Care 2021 06 1;25(1):189. Epub 2021 Jun 1.

Department of Medicine - DIMED, Section of Anesthesiology and Intensive Care, University of Padua, Padua, Italy.

Background: Usefulness of noninvasive ventilation (NIV) in weaning patients with non-hypercapnic hypoxemic acute respiratory failure (hARF) is unclear. The study aims to assess in patients with non-hypercapnic hARF, the efficacy of NIV after early extubation, compared to standard weaning.

Methods: In this individual patient data meta-analysis, we searched EMBASE, Medline and Cochrane Central Register of Controlled Trials to identify potentially eligible randomized controlled trials published from database inception to October 2020. Read More

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Small Molecule Compounds Identified from Mixture-Based Library Inhibit Binding between Infected Erythrocytes and Endothelial Receptor ICAM-1.

Int J Mol Sci 2021 May 26;22(11). Epub 2021 May 26.

Charles E. Schmidt College of Medicine, Florida Atlantic University, Boca Raton, FL 33428, USA.

Specific adhesion of parasite-infected erythrocytes (IE) in deep vascular beds can result in severe complications, such as cerebral malaria, placental malaria, respiratory distress, and severe anemia. Cerebral malaria and severe malaria syndromes were associated previously with sequestration of IE to a microvasculature receptor ICAM-1. The screening of Torrey Pines Scaffold Ranking library, which consists of more than 30 million compounds designed around 75 molecular scaffolds, identified small molecules that inhibit cytoadhesion of ICAM-1-binding IE to surface-immobilized receptor at IC range down to ~350 nM. Read More

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Estimations on Properties of Redox Reactions to Electrical Energy and Storage Device of Thermoelectric Pipe (TEP) Using Polymeric Nanofluids.

Polymers (Basel) 2021 May 31;13(11). Epub 2021 May 31.

Department of Marine Engineering (DME), National Taiwan Ocean University (NTOU), Keelung 202301, Taiwan.

A thermoelectric pipe (TEP) is constructed by tubular graphite electrodes, Teflon material, and stainless-steel tube containing polymeric nanofluids as electrolytes in this study. Heat dissipation and power generation (generating capacity) are both fulfilled with temperature difference via the thermal-electrochemistry and redox reaction effects of polymeric nanofluids. The notion of TEP is to recover the dissipative heat from the heat capacity generated by the relevant machine systems. Read More

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