Development of microwave assisted oxidative desulfurization of petroleum oils: A review

Hui Shang,Zhichang Liu,Haichao Zhang,Wei Du 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.5

This paper provides a general overview of microwave applications in petroleum oxidative desulfurization (ODS). It was concluded that, as compared with conventional heating technologies,milder reaction conditions could be used and higher ODS rate could be achieved under microwave treatment. It was also found that microwave power level, treatment time, temperature, oxidizing agent dosage, microwave equipment and catalyst are the key operating factors influencing the ODS efficiency. A best removal rate of 96% achieved for diesel. The main challenges are developing high efficiency, novel techniques and apparatuses to remove sulfur from oils in a commercial process.

Development of microwave induced hydrodesulfurization of petroleum streams: A review

Hui Shang,Wei Du,Zhichang Liu,Haichao Zhang 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.4

This paper provides a general overview of microwave applications in hydrodesulfurization (HDS) of various petroleum streams. Deep desulfurization is required for petroleum streams due to stringent sulfur specifications to meet environmental norms. The progress achieved during recent years in catalyst-based HDS technologies is illustrated by using microwaves due to its unique selective and volumetric heating capacity. Based on literature reports, it may be concluded that microwave assisted desulfurization of petroleum streams can be successfully performed under less severe conditions, with significant advantages. This is expected to result in savings in utilities, catalyst consumption, eventually leading to increased fuel yields.

A rigid donor–acceptor daisy chain dimer

Cao, Dennis,Wang, Cheng,Giesener, Marc A.,Liu, Zhichang,Stoddart, J. Fraser The Royal Society of Chemistry 2012 Chemical communications Vol.48 No.54

<P>A functionalised cyclobis(paraquat-<I>p</I>-phenylene) attached by a rigid linker to a tetrathiafulvalene unit, which is incapable of self-complexation, forms preferentially a [<I>c</I>2]daisy chain which undergoes rapid disassociation and reassociation on the <SUP>1</SUP>H NMR time-scale above room temperature.</P> <P>Graphic Abstract</P><P>A functionalised cyclobis(paraquat-<I>p</I>-phenylene) attached by a rigid linker to a tetrathiafulvalene unit, which is incapable of self-complexation, forms preferentially a [<I>c</I>2]daisy chain which undergoes rapid disassociation and reassociation on the <SUP>1</SUP>H NMR time-scale above room temperature. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2cc32499g'> </P>

Controlling Switching in Bistable [2]Catenanes by Combining Donor–Acceptor and Radical–Radical Interactions

Zhu, Zhixue,Fahrenbach, Albert C.,Li, Hao,Barnes, Jonathan C.,Liu, Zhichang,Dyar, Scott M.,Zhang, Huacheng,Lei, Juying,Carmieli, Raanan,Sarjeant, Amy A.,Stern, Charlotte L.,Wasielewski, Michael R.,Sto American Chemical Society 2012 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.134 No.28

<P>Two redox-active bistable [2]catenanes composed of macrocyclic polyethers of different sizes incorporating both electron-rich 1,5-dioxynaphthalene (DNP) and electron-deficient 4,4′-bipyridinium (BIPY<SUP>2+</SUP>) units, interlocked mechanically with the tetracationic cyclophane cyclobis(paraquat-<I>p</I>-phenylene) (CBPQT<SUP>4+</SUP>), were obtained by donor–acceptor template-directed syntheses in a threading-followed-by-cyclization protocol employing Cu(I)-catalyzed azide–alkyne 1,3-dipolar cycloadditions in the final mechanical-bond forming steps. These bistable [2]catenanes exemplify a design strategy for achieving redox-active switching between two translational isomers, which are driven (i) by donor–acceptor interactions between the CBPQT<SUP>4+</SUP> ring and DNP, or (ii) radical–radical interactions between CBPQT<SUP>2(•+)</SUP> and BIPY<SUP>•+</SUP>, respectively. The switching processes, as well as the nature of the donor–acceptor interactions in the ground states and the radical–radical interactions in the reduced states, were investigated by single-crystal X-ray crystallography, dynamic <SUP>1</SUP>H NMR spectroscopy, cyclic voltammetry, UV/vis spectroelectrochemistry, and electron paramagnetic resonance (EPR) spectroscopy. The crystal structure of one of the [2]catenanes in its trisradical tricationic redox state provides direct evidence for the radical–radical interactions which drive the switching processes for these types of mechanically interlocked molecules (MIMs). Variable-temperature <SUP>1</SUP>H NMR spectroscopy reveals a degenerate rotational motion of the BIPY<SUP>2+</SUP> units in the CBPQT<SUP>4+</SUP> ring for both of the two [2]catenanes, that is governed by a free energy barrier of 14.4 kcal mol<SUP>–1</SUP> for the larger catenane and 17.0 kcal mol<SUP>–1</SUP> for the smaller one. Cyclic voltammetry provides evidence for the reversibility of the switching processes which occurs following a three-electron reduction of the three BIPY<SUP>2+</SUP> units to their radical cationic forms. UV/vis spectroscopy confirms that the processes driving the switching are (i) of the donor–acceptor type, by the observation of a 530 nm charge-transfer band in the ground state, and (ii) of the radical–radical ilk in the switched state as indicated by an intense visible absorption (ca. 530 nm) and near-infrared (ca. 1100 nm) bands. EPR spectroscopic data reveal that, in the switched state, the interacting BIPY<SUP>•+</SUP> radical cations are in a fast exchange regime. In general, the findings lay the foundations for future investigations where this radical–radical recognition motif is harnessed in bistable redox-active MIMs in order to achieve close to homogeneous populations of co-conformations in both the ground and switched states.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2012/jacsat.2012.134.issue-28/ja3037355/production/images/medium/ja-2012-037355_0011.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja3037355'>ACS Electronic Supporting Info</A></P>

Microbial short-chain fatty acids: a bridge between dietary fibers and poultry gut health — A review

Ali Qasim,Ma Sen,La Shaokai,Guo Zhiguo,Liu Boshuai,Gao Zimin,Farooq Umar,Wang Zhichang,Zhu Xiaoyan,Cui Yalei,Li Defeng,Shi Yinghua 아세아·태평양축산학회 2022 Animal Bioscience Vol.35 No.10

The maintenance of poultry gut health is complex depending on the intricate balance among diet, the commensal microbiota, and the mucosa, including the gut epithelium and the superimposing mucus layer. Changes in microflora composition and abundance can confer beneficial or detrimental effects on fowl. Antibiotics have devastating impacts on altering the landscape of gut microbiota, which further leads to antibiotic resistance or spread the pathogenic populations. By eliciting the landscape of gut microbiota, strategies should be made to break down the regulatory signals of pathogenic bacteria. The optional strategy of conferring dietary fibers (DFs) can be used to counterbalance the gut microbiota. DFs are the non-starch carbohydrates indigestible by host endogenous enzymes but can be fermented by symbiotic microbiota to produce shortchain fatty acids (SCFAs). This is one of the primary modes through which the gut microbiota interacts and communicate with the host. The majority of SCFAs are produced in the large intestine (particularly in the caecum), where they are taken up by the enterocytes or transported through portal vein circulation into the bloodstream. Recent shreds of evidence have elucidated that SCFAs affect the gut and modulate the tissues and organs either by activating G-protein-coupled receptors or affecting epigenetic modifications in the genome through inducing histone acetylase activities and inhibiting histone deacetylases. Thus, in this way, SCFAs vastly influence poultry health by promoting energy regulation, mucosal integrity, immune homeostasis, and immune maturation. In this review article, we will focus on DFs, which directly interact with gut microbes and lead to the production of SCFAs. Further, we will discuss the current molecular mechanisms of how SCFAs are generated, transported, and modulated the pro-and anti-inflammatory immune responses against pathogens and host physiology and gut health. The maintenance of poultry gut health is complex depending on the intricate balance among diet, the commensal microbiota, and the mucosa, including the gut epithelium and the superimposing mucus layer. Changes in microflora composition and abundance can confer beneficial or detrimental effects on fowl. Antibiotics have devastating impacts on altering the landscape of gut microbiota, which further leads to antibiotic resistance or spread the pathogenic populations. By eliciting the landscape of gut microbiota, strategies should be made to break down the regulatory signals of pathogenic bacteria. The optional strategy of conferring dietary fibers (DFs) can be used to counterbalance the gut microbiota. DFs are the non-starch carbohydrates indigestible by host endogenous enzymes but can be fermented by symbiotic microbiota to produce shortchain fatty acids (SCFAs). This is one of the primary modes through which the gut microbiota interacts and communicate with the host. The majority of SCFAs are produced in the large intestine (particularly in the caecum), where they are taken up by the enterocytes or transported through portal vein circulation into the bloodstream. Recent shreds of evidence have elucidated that SCFAs affect the gut and modulate the tissues and organs either by activating G-protein-coupled receptors or affecting epigenetic modifications in the genome through inducing histone acetylase activities and inhibiting histone deacetylases. Thus, in this way, SCFAs vastly influence poultry health by promoting energy regulation, mucosal integrity, immune homeostasis, and immune maturation. In this review article, we will focus on DFs, which directly interact with gut microbes and lead to the production of SCFAs. Further, we will discuss the current molecular mechanisms of how SCFAs are generated, transported, and modulated the pro-and anti-inflammatory immune responses against pathogens and host physiology and gut health.

A Semiconducting Organic Radical Cationic Host–Guest Complex

Fahrenbach, Albert C.,Sampath, Srinivasan,Late, Dattatray J.,Barnes, Jonathan C.,Kleinman, Samuel L.,Valley, Nicholas,Hartlieb, Karel J.,Liu, Zhichang,Dravid, Vinayak P.,Schatz, George C.,Van Duyne, R American Chemical Society 2012 ACS NANO Vol.6 No.11

<P>The self-assembly and solid-state semiconducting properties of single crystals of a trisradical tricationic complex composed of the diradical dicationic cyclobis(paraquat-<I>p</I>-phenylene) (CBPQT<SUP>2(•+)</SUP>) ring and methyl viologen radical cation (MV<SUP>•+</SUP>) are reported. An organic field effect transistor incorporating single crystals of the CBPQT<SUP>2(•+)</SUP>⊂MV<SUP>•+</SUP> complex was constructed using lithographic techniques on a silicon substrate and shown to exhibit <I>p</I>-type semiconductivity with a mobility of 0.05 cm<SUP>2</SUP> V<SUP>–1</SUP> s<SUP>–1</SUP>. The morphology of the crystals on the silicon substrate was characterized using scanning electron microscopy which revealed that the complexes self-assemble into “molecular wires” observable by the naked-eye as millimeter long crystalline needles. The nature of the recognition processes driving this self-assembly, radical–radical interactions between bipyridinium radical cations (BIPY<SUP>•+</SUP>), was further investigated by resonance Raman spectroscopy in conjunction with theoretical investigations of the vibrational modes, and was supported by X-ray structural analyses of the complex and its free components in both their radical cationic and dicationic redox states. These spectroscopic investigations demonstrate that the bond order of the BIPY<SUP>•+</SUP> radical cationic units of host and guest components is not changed upon complexation, an observation which relates to its conductivity in the solid-state. We envision the modularity inherent in this kind of host–guest complexation could be harnessed to construct a library of custom-made electronic organic materials tailored to fit the specific needs of a given electronic application.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2012/ancac3.2012.6.issue-11/nn303553z/production/images/medium/nn-2012-03553z_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn303553z'>ACS Electronic Supporting Info</A></P>

Solution-Phase MechanisticStudy and Solid-State Structureof a Tris(bipyridinium radical cation) Inclusion Complex

Fahrenbach, AlbertC.,Barnes, Jonathan C.,Lanfranchi, Don Antoine,Li, Hao,Coskun, Ali,Gassensmith, Jeremiah J.,Liu, Zhichang,Bení,tez, Diego,Trabolsi, Ali,Goddard, William A.,Elhabiri, Mourad,Sto American Chemical Society 2012 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.134 No.6

<P>The ability of the diradical dicationic cyclobis(paraquat-<I>p</I>-phenylene) (CBPQT<SUP>2(•+)</SUP>) ring to forminclusion complexes with 1,1′-dialkyl-4,4′-bipyridiniumradical cationic (BIPY<SUP>•+</SUP>) guests has been investigatedmechanistically and quantitatively. Two BIPY<SUP>•+</SUP> radicalcations, methyl viologen (MV<SUP>•+</SUP>) and a dibutynylderivative (V<SUP>•+</SUP>), were investigated as guests forthe CBPQT<SUP>2(•+)</SUP> ring. Both guests form trisradicalcomplexes, namely, CBPQT<SUP>2(•+)</SUP>⊂MV<SUP>•+</SUP> and CBPQT<SUP>2(•+)</SUP>⊂V<SUP>•+</SUP>, respectively.The structural details of the CBPQT<SUP>2(•+)</SUP>⊂MV<SUP>•+</SUP> complex, which were ascertained by single-crystalX-ray crystallography, reveal that MV<SUP>•+</SUP> is locatedinside the cavity of the ring in a centrosymmetric fashion: the 1:1complexes pack in continuous radical cation stacks. A similar solid-statepacking was observed in the case of CBPQT<SUP>2(•+)</SUP> byitself. Quantum mechanical calculations agree well with the superstructurerevealed by X-ray crystallography for CBPQT<SUP>2(•+)</SUP>⊂MV<SUP>•+</SUP> and further suggest an electronicasymmetry in the SOMO caused by radical-pairing interactions. Theelectronic asymmetry is maintained in solution. The thermodynamicstability of the CBPQT<SUP>2(•+)</SUP>⊂MV<SUP>•+</SUP> complex was probed by both isothermal titration calorimetry (ITC)and UV/vis spectroscopy, leading to binding constants of (5.0 ±0.6) × 10<SUP>4</SUP> M<SUP>–1</SUP> and (7.9 ± 5.5)× 10<SUP>4</SUP> M<SUP>–1</SUP>, respectively. The kineticsof association and dissociation were determined by stopped-flow spectroscopy,yielding a <I>k</I><SUB>f</SUB> and <I>k</I><SUB>b</SUB> of (2.1 ± 0.3) × 10<SUP>6</SUP> M<SUP>–1</SUP> s<SUP>–1</SUP> and 250 ± 50 s<SUP>–1</SUP>, respectively.The electrochemical mechanistic details were studied by variable scanrate cyclic voltammetry (CV), and the experimental data were compareddigitally with simulated data, modeled on the proposed mechanism usingthe thermodynamic and kinetic parameters obtained from ITC, UV/vis,and stopped-flow spectroscopy. In particular, the electrochemicalmechanism of association/dissociation involves a bisradical tetracationicintermediate CBPQT<SUP>(2+)(•+)</SUP>⊂V<SUP>•+</SUP> inclusion complex; in the case of the V<SUP>•+</SUP> guest,the rate of disassociation (<I>k</I><SUB>b</SUB> = 10 ±2 s<SUP>–1</SUP>) was slow enough that it could be detectedand quantified by variable scan rate CV. All the experimental observationslead to the speculation that the CBPQT<SUP>(2+)(•+)</SUP> ringof the bisradical tetracation complex might possess the unique propertyof being able to recognize both BIPY<SUP>•+</SUP> radical cationand π-electron-rich guests simultaneously. The findings reportedherein lay the foundation for future studies where this radical–radicalrecognition motif is harnessed particularly in the context of mechanicallyinterlocked molecules and increases our fundamental understandingof BIPY<SUP>•+</SUP> radical–radical interactions insolution as well as in the solid-state.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jacsat/2012/jacsat.2012.134.issue-6/ja2089603/production/images/medium/ja-2011-089603_0004.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ja2089603'>ACS Electronic Supporting Info</A></P>