Emeriti

gad_marom

Prof. Gad Marom

Casali 357
02 6586 068

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EDUCATION

B.Sc. -  (Chemistry and Physics) The Hebrew University of Jerusalem, 1968.
M.Sc. -  (Organic chemistry) The Hebrew University of Jerusalem, 1970.
Ph.D. -  (Polymer and Fibre Science) The Faculty of Technology (UMIST), The University of Manchester, 1972.

 

PROFESSIONAL EXPERIENCE

Academic Appointments:
Professor of Applied Chemistry (from 1985), Associate Professor (1980), Senior Lecturer (1976), Lecturer (1973), Instructor (1972).

Main Administrative Positions at HUJI:
Head, Casali Institute of Applied Chemistry (1984-1987)
Head, Graduate School of Applied Science and Tecnology (1987-1990)
Head, the University's Scientific Infrastructure Committee (1999-2002)
Head, the University's Development Program Committee (2006-2008)
Dean, Faculty of Mathematics and Science (2008-2012)

Visiting Positions:
School of Materials Science and Engineering, NTU, Singapore (2015, 2013); Dept. of Mechanical Engineering, HKUST, Hong Kong (2013, 2005); Dept. of Mechanical Engineering, Kyoto University, Japan (2005); Garcia Center, SUNY Stony Brook (2012, 2005, 2002); Dept. of Chemistry, SUNY Stony Brook (2005, 2002); Dept. of Materials Engineering, Trento University, Italy (2008, 1993, 1990); Pioneering Research Laboratory, Textile Fiber Dept., E.I. du Pont de Nemours & Co, Wilmington (1985); Dept. of Metallurgical & Materials Engineering, IIT, Chicago (1980); Dept. of Physics, Bristol University, Britain (1975).

Editorial Board Member:
Composites Part A: Applied Science and Manufacturing (until 2015).
International Journal of Adhesion and Adhesives (until 2009).
Polymer Composites.
Applied Composite Materials.
Advanced Composites Letters (until 2010).
Science and Engineering of Composite Materials (until 1995).
Materiale Plastice.
Kompozyty (Composites) - Research Journal of the Polish Society of Composite Materials.

Professional Societies:
Fellow of the Society of Plastics Engineers, SPE (2004); Chairman of the Israeli Section of the Society for Advancement of Materials & Process Engineering, SAMPE (1996-7); President of the Israel Society of Polymers and Plastics (1992-4).

 

 

RESEARCH INTERESTS

Composite materials, polymers and nanocomposites: Multi dimension structural morphology - property correlations.

 

CURRENT RESEARCH PROJECTS

  • Specific placement of nanoreinforcement in critical sites: a novel method for property improvement of composite materials.
  • Supra-molecular morphology in thermoplastic polymer nano-composites induced by nano-fillers and flow.
  • Metal-organic nanocomposites and their properties. (with Prof. D. Avnir)
  • Compacts of polyacrylonitrile for fire protection in ballistic and automotive applications.
  • Hydrophilic nanofibers from micro emulsions by electrospinning. (with Prof. S. Magdassi)
  • A biomimetic structural perspective of the mechanical properties of tendons. (with Prof. H.D. Wagner)
  • Three Dimensional (3D) functional printing. (with Prof. S. Magdassi)

 

 

Selected Recent Publications

  1. G.A. Tanami, Liliya Kovalenko, Chung Chueh Chang, M. Rafailovich, G.Marom,
    Morphology Related Bulk and Surface Mechanical Properties of Ultra-Low Diameter VGCF-iPP Monofilament Nanocomposites under Potential Confinement Conditions, Nanocomposites, 1 (2015) 18-26
  2. Hila Klein Selle, Benny Bar-On, Gad Marom, H. Daniel Wagner,
    Gelatin yarns inspired by tendons - Structural and mechanical perspectives gelatin yarns inspired by tendons - Structural and mechanical perspectives, Mater.Sci.Eng. C, 47 (2015) 1-7.
  3. Viktoriya Gordon, Gad Marom, Shlomo Magdassi,
    Formation of Hydrophilic Nanofibers from Nanoemulsions through Electrospinning, International Journal of Pharmaceutics, 478 (2015) 172–179.
  4. Gad Marom and Golan Tanami,
    Interparticle confinement in nanocomposites, SPE Plastics Research Online, (2015) 10.2417/spepro.005834
  5. G.A. Tanami, Ellen Wachtel, G. Marom,
    Crystalline Structure and Thermodynamic Analysis of Ultra-Low Diameter VGCF-Polypropylene Nanocomposite Monofilaments, Polymer Composites, 37 (2016) 1641-9, DOI: 10.1002/pc.23336.
  6. T. Lyashenko-Miller, J. Fitoussi, G. Marom,
    The loading rate effect on Mode II fracture toughness of composites interleaved with CNT nanocomposites, Nanocomposites, 2 (2016) 1-7, DOI 10.1080/20550324.2016.1159372
  7. Y. Aouat, G. Marom, D. Avnir,
    Corrosion-Resistant Hybrid Nanoparticles of Polydimethylsiloxane@Fe, based on Fe(CO)5 Thermolysis, European J. Inorganic Chem., 2016 (2016) 1488–1496, DOI:10.1002/ejic.201501492
  8. Xuelong Chen, Yen Nan Liang, Ming Yin, Sunanda Roy, Gad Marom, Yongfeng Men, Xiao Hu,
    Exceptional Enhancement of Ductility and Toughness in Poly(vinylidene fluoride)/Carbon Nanotubes Composites, J. Appl. Polym. Sci., 133, (2016), DOI: 10.1002/app.43610
  9. T. Lyashenko-Miller and G. Marom,
    Delamination fracture toughness of UHMWPE fibers/Polyurethane laminates interleaved with carbon nanotubes-reinforced polyurethane films, Polymers for Advanced Technologies, 28 (2017) 606–612, 1 JUL 2016 | DOI: 10.1002/pat.3848
  10. Gad Marom, H. Daniel Wagner,
    Should polymer nanocomposites be regarded as molecular composites? J. Mater. Sci.,  52 8357-8361 (2017) DOI 10.1007/s10853-017-1113-7
  11. Nadya Stern, Gad Marom, Liying Zhang, Xiao Hu,
    Micromechanics of Nanocomposites. In: Beaumont, P. W.R. and Zweben, C.H. (eds.), Comprehensive Composite Materials II. vol. 6, 6.1 (2018) 1–27. Oxford: Academic Press
  12. N. Stern, I. Dyamant, E. Shemer, X. Hu and G. Marom,
    Hybrid effects in the fracture toughness of polyvinyl butyral-based nanocomposites, Nanocomposites, 4 (2018) 1-9
  13. Yair shalom, Ellen Wachtel and Gad Marom,
    Restructuring of confined crystalline morphology in the drawing process of VGCF-iPP nanocomposite filaments, Polymer, 154 (2018) 218-224
  14. L. WiegartG. S. DoerkM. FukutoS. LeeR. LiG. MaromM. M. NoackC. O. OsujiM. H. RafailovichJ. A. SethianY. ShmueliM. Torres ArangoK. TothK. G. YagerR. Pindak,
    Instrumentation for In situ/Operando X-ray Scattering Studies of Polymer Additive Manufacturing Processes, Synchrotron Radiation News, 32 (2) (2019) 20-27,  ISSN 0894-0886
  15. Yuval Shmueli, Jiaolong Jiang, Yuchen Zhou, Yuan Xue, Chung-Chueh Chang, Guangcui Yuan, Sushil Satija, Sungsik Lee, Chang-Yong Nam, Taejin Kim, Gad Marom, Dilip Gersappe, Miriam Rafailovich,
    Simultaneous in-situ X-ray scattering and infrared imaging of polymer extrusion in additive manufacturing, ACS Applied Polymer Materials, 1(6) (2019) 1559-1567 
  16. Yuval Shmueli, Yu-Chung Lin, Sungsik Lee, Mikhail Zhernenkov Rina Tannenbaum, Gad Marom, Miriam Rafailovich,
    In-situ time resolved X-ray scattering study of isotactic polypropylene in additive manufacturing, ACS Applied Materials & Interfaces, 11(40) (2019) 37112-37120
  17. Nadya Stern, Xiao Hu, Gad Marom,
    The effects of geometry and chemical composition of nanoparticles on the fracture toughness of iPP nanocomposites, J. Compos. Sci., 24(4) (2020) article no. 24
  18. Yuval Shmueli, Yu-Chung Lin, Xianghao Zuo, Yichen Guo, Sungsik Lee, Mikhail Zhernenkov, Taejin Kim, Rina Tannenbaum, Gad Marom, Dilip Gersappe and Miriam H. Rafailovich,
    In-situ X-ray Scattering Study of Isotactic Polypropylene/Graphene Nanocomposites Under Shear During Fused Deposition Modeling 3D Printing, Composites Science and Technology,  196 (2020) 108227
  19. Gad Marom, H.Daniel Wagner,
    A perspective on the structure and properties of nanocomposites, Polymer Composites, 41 (2020) 2986-2989
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shaik_sason_s

Prof. Sason S. Shaik

Professor of Chemistry
Alberman 64
02 6585 909

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Saeree K. and Louis P. Fiedler Chair in Chemistry 

• Ph.D., 1978, The University of Washington (Seattle)

• B.Sc. and M.Sc., 1974, Bar Ilan University

 

Research Focus:
We use theory to find broad general patterns in chemistry and to make predictions, which can hopefully guide new experiments. Our interest stretches from bonding in small molecules all the way to metalloenzymes and neuronal receptors. To these ends we use an arsenal of theoretical methods:

•  Bonding in small molecules is studied with valence bond (VB) theory or multi-reference methods such as MRCI, CASSCF and CASPT2.

•  Reactivity of small molecules is studied with density functional theory (DFT), coupled cluster theory and multi-reference methods. The reactivity patterns are subsequently organized by usage of VB modeling.

• Structure and reactivity of metalloenzymes are studied by means of DFT and hybrid DFT/ molecular mechanical (MM) methods, hence DFT/MM. 

•  For metalloenzymes and neuronal receptors we use molecular dynamic (MD) simulations.

Here are some representative research topics:

 

Charge-shift bonding and no-pair ferromagnetic bonding
Examples of new bonding motifs, which we discovered and analyzed by applying VB theory, are the charge-shift bonds (CSB) and the no-pair ferromagnetic bonds (NPFMB). CSBs are electron pair bonds, which are neither covalent nor ionic, and in which the bonding energy arises from the covalent-ionic resonance energy.  F2 is an archetypical CSB; it has a repulsive covalent structure and hence its electron density map, called ELF (shown below on the right hand side), is unique, exhibiting depleted electron density in the bonding region. The right-hand side drawing shows a 12Li11 cluster, which is sustained by bound triplet pairs, which is the bonding mode in NPFMB.  VB theory was also used to discover the quadruple bonding of carbon in C2, and other isoelectronic species.

shaik_sason_s1

 

Halogen bonding and C-H ••• H-C interactions
Our studies extend to weak intermolecular interaction for which the VB method reveals that the bonding arises either completely due to resonance with the charge transfer form, as in the case of halogen bonds (e.g., H3N: ••• Cl-Cl) depicted on the left- hand side drawing, or partly as in the graphane dimers on the right-hand side. The charge transfer binding in these dimers is brought about by interactions of C-H ••• H-C pairs, and it contributes inter-sheet electron density accumulation that acts as a two-way adhesive between the sheets.

shaik_sason_s2

shaik_sason_s3

 

VB modeling of hydrogen abstraction reactivity
VB theory can be used to derive general models, which predict barriers for any desired reaction.  The drawing below shows a correlation of these model barriers for more than 40 different hydrogen abstraction reactions, plotted against reference barriers calculated with CCSD(T)/CBS and B3LYP.

shaik_sason_s4

shaik_sason_s5

 

Cytochrome P450 enzymes
Metalloenzymes like cytochrome P450s hold great many fascinating challenges for the theoretician.  For example, the above right drawing shows how does the enzyme P450 Stap uses a proton-shuttle bridge made from two water molecules (Wat644 and Wat789) and a histidine residue (His250) which initiates the formation of Staurosporine (a natural cancer-cells killer) by inducing C-C bond formation in the molecule chromopyrrolic acid (CPA), which is very distant from the iron-oxo prophyrin active species (at the bottom of the drawing).

 

The exchange-enhanced reactivity principle
The reactivity of metal-oxo complexes (analogs of nonheme enzymes) is fascinating since it involves different spin states, which reveal new principles of reactivity. One of these is so-called exchange enhanced reactivity (EER) principle, which occurs in reactions wherein the number of unpaired electrons on the transition metal center increases in the transition state thereby lowering its energy by enhanced exchange. This is the Hund’s Rule of chemical reactivity.

 

Other topics in chemical reactivity
We explore the usage of oriented electric fields on the reactivity of molecules and enzymes. We began recently to look at proton-coupled electron transfer (PCET) reactions.


 

Selected Publications

1.       A Chemist’s Guide to Valence Bond Theory, by S. Shaik and P.C. Hiberty, Wiley Interscience, Hoboken New Jersey (2008).
2.       Charge-Shift Bonding and its manifestations in chemistry, by S. Shaik, D. Danovich, W. Wu and P.C. Hiberty, Nature Chem. 1, 443-449 (2009).
3.       Bonding with parallel spins: High spin clusters of monovalent metal atoms, by D. Danovich and S. Shaik, Acc. Chem. Res. 47, 417-426 (2014).
4.       On the nature of the halogen bond, by C. Wang, D. Danovich, Y. Mo and S. Shaik, J. Chem. Theor. Comput. 10, 3726-3737 (2014).
5.       A tutorial for understanding chemical reactivity through the valence bond approach, by U. Dandamudi, W.Z. Lai, C. Li, D. Danovich, H. Chen and S. Shaik, Chem. Soc. Rev. 43, 4968-4988 (2014).
6.       P450 enzymes: Their structure, reactivity, and selectivity, modeled by QM/MM calculations, by S. Shaik, S. Cohen, Y. Wang, H. Chen, D. Kumar and W. Thiel, Chem. Rev. 110, 949-1017 (2010).
7.       A theory of bioinorganic chemistry of oxometal complexes and ananlogous oxidants: The exchange and orbital-selection rules, by U. Dandamudi, D. Janardanan, C. Li and S. Shaik, Acc. Chem. Res. 46, 471-482 (2013). 

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