DNA compaction by poly (amido amine) dendrimers of ammonia cored and ethylene diamine cored

The complexes build–up of DNA and soft particles poly amidoamine (PAMAM) dendrimers of ammonia cored of generations (G1-G6) and ethylenediamine cored of generations (G1-G10) have been studied, using a new theoretical model developed by Qamhieh and coworkers. The model describes the interaction between linear polyelectrolyte (LPE) chain and ion-penetrable spheres. Many factors affecting LPE/dendrimer complex have been investigated such as dendrimer generation, the Bjerrum length, salt concentration, and rigidity of the LPE chain represented by the persistence length. It is found that the wrapping chain length around dendrimer increases by increasing dendrimer`s generation, Bjerrum length, and salt concentration, while decreases by increasing the persistence length of the LPE chain. Also we can conclude that the wrapping length of LPE chain around ethylenediamine cored dendrimers is larger than its length around ammonia cored dendrimers

Nucleosomes in gene regulation: theoretical approaches

This work reviews current theoretical approaches of biophysics and bioinformatics for the description of nucleosome arrangements in chromatin and transcription factor binding to nucleosomal organized DNA. The role of nucleosomes in gene regulation is discussed from molecular-mechanistic and biological point of view. In addition to classical problems of this field, actual questions of epigenetic regulation are discussed. The authors selected for discussion what seem to be the most interesting concepts and hypotheses. Mathematical approaches are described in a simplified language to attract attention to the most important directions of this field

Effect of discrete macroion charge distributions in solutions of like-charged macroions

The effect of replacing the conventional uniform macroion surface charge density with discrete macroion charge distributions on structural properties of aqueous solutions of like-charged macroions has been investigated by Monte Carlo simulations. Two discrete charge distributions have been considered: point charges localized on the macroion surface and finite-sized charges protruding into the solution. Both discrete charge distributions have been examined with fixed and mobile macroion charges. Different boundary conditions have been applied to examine various properties. With point charges localized on the macroion surface, counterions become stronger accumulated to the macroion and the effect increases with counterion valence. As a consequence, with mono- and divalent counterions the potential of mean force between two macroions becomes less repulsive and with trivalent counterions more attractive. With protruding charges, the excluded volume effect dominates over the increased correlation ability; hence the counterions are less accumulated near the macroions and the potential of mean force between two macroions becomes more repulsive/less attractive. (c) 2005 American Institute of Physics

Fabrication and characterization of size-selected Cu nanoclusters using a magnetron sputtering source

Copper nanoclusters are used widely in applications such as glucose and gas sensors. A physical method is used to produce copper nanoclusters utilizing an ultra-high vacuum (UHV) system. Using a quadrupole mass filter (QMF), the size distribution of the nanoclusters is determined. It is found that varying the source parameters controls the size of the produced Cu nanoclusters. Increasing the aggregation length increases the nanocluster size. Varying the inert gas flow rate has a minor effect on the size at low aggregation length. On the other hand, at high aggregation length the size increases with increasing the gas flow. The results are interpreted in terms of the nucleation time and a two-body collision model between nanoclusters. Moreover, the band gap is measured for different sizes of CuO nanoclusters. ? 2018 Elsevier B.V.Center for Innovative Technology, United Arab Emirates UniversityScopu

Design, fabrication, and characterization of Hg2+ sensor based on graphite oxide and metallic nanoclusters

In this paper, sensors with field-effect transistor structure have been developed to detect low concentration of mercury ions (Hg2+) in water. These sensors are based on graphite oxide decorated with silver nanoclusters, where the change in the electrical current signal is the sensing parameter. By utilizing thermal evaporation process, interdigitated electrodes of gold were deposited on the surface of the sensor substrates. Graphite oxide (GO) was assembled between the interdigitated electrodes. Silver nanoclusters were generated inside an ultra-high vacuum (UHV) compatible system by sputtering and inert-gas condensation technique; then they were self-assembled on top of the graphite oxide. Each sensor was subjected to different concentrations of Hg2+ to test its sensitivity. The sensors showed better performance when incorporating silver nanoclusters with graphite oxide. The selectivity of the fabricated sensors was further investigated by testing different metal ions, and it revealed optimum response to Hg2+ among other metal ions, which makes them preferable for practical applications. - 2018 Elsevier B.V.The authors would like to acknowledge the financial support by United Arab Emirates University with Fund number 31R006 & 31N187 . Mr. Abdul Rehman Said Rehman has received his Bachelor Degree in Electrical Engineering from UAE University, Al Ain, UAE in 2013. Currently, he is completing his Master Degree in Electrical Engineering at UAE University. His Master thesis title is �Design, Fabrication, and Characterization of Hg 2+ Sensor Based on Graphite Oxide and Metallic Nanoclusters�. In 2013, he completed successfully the Young Future Energy Leaders Program (YFEL) (Outreach Program) which was held at Masdar Institute, Abu Dhabi, UAE. And he attended four (YFEL) courses on �Being a Future Leader�, �Fabrication and Characterization of Solar Cell Devices�, �The Role of Policy on Renewable Energy Industry� and �Water Science and Technology�. Ms. Khadija Said is a Research Assistant, in Electrical Engineering Department, United Arab Emirates University, Al Ain, United Arab Emirates. Ms. Khadija Said has received her Bachelor and Master Degree in Physics in United Arab Emirates University. Her Master Thesis was on Fabrication and characterization of graphite oxide based field effect transistors for glucose-sensor applications. She has three published papers. Her current research is focused on Glucose, Mercury, and gas sensors by using nanotechnology. In 2010, she was an Associated Member of the Personnel of the European Organization for Nuclear Research in CERN, Geneva, Switzerland. Dr. Falah Awwad received the M.A. Sc. and Ph.D. degrees in Electrical and Computer Engineering from Concordia University (Montreal, QC, Canada) in 2002 and 2006, respectively. He was a Post-Doctoral Fellow at Ecole Polytechnique de Montr�al and Concordia University, Montreal, QC, Canada. Between August 2007 and Feb. 2013, he was an Assistant Professor with the College of Information Technology (CIT) at United Arab Emirates University. Currently, he is an Associate Professor with the Department of Electrical Engineering � College of Engineering (UAE University). He published over 50 research articles in refereed international journals and conferences. He is a member of the editorial Board of Journal of �Nanomaterials & Molecular Nanotechnology� and "Austin Journal of Nanomedicine & Nanotechnology". He is the recipient of the CIT Faculty Outstanding Service Award. The evaluation was done based on his professional and community service during the period 2009�2012. His scientific research interests are VLSI circuits & systems, sensors, nanodevices, and biomedical imaging systems. Prof. Naser N. Qamhieh received his Ph.D. in Physics in 1996 from the University of Leuven (Belgium) where he worked with professor Guy Adriaenssens. He joined the Department of Physics at United Arab Emirates University (UAEU) in 1999 where he is presently a full professor. His research interest centers on experimental study of the electronic properties and density of states of amorphous semiconductors and chalcogenide glasses. Among materials of interest are phase change materials used in memory devices. His research also involves fabrication and characterization thin films and nanoclusters by the existing techniques in UAEU labs. He published over 50 research articles in refereed international journals and conferences. He was honored a Research Project Award by the Research Affairs at UAE University in 2009. Moreover, he has a rich experience in teaching and developing general physics courses in UAEU. He is dedicated to enhance students� learning, and conducted several educational studies based on teaching innovations for introductory physics courses. He had several contributions to pedagogical journals and conferences. For research in pedagogy he was honored the 2009�2010 Faculty of Science Recognition Award for Excellence in Teaching and Learning. Prof. Saleh obtained his Ph.D. in Physics from Indian Institute of Technology-Delhi (India 2001). He is a full professor at UAE University and has 14 years� experience in laser-plasma interactions, materials characterization and nanodevices fabrication. His publication record includes about 42 publications in international peer-reviewed journals and more than 25 presentations in international conferences. He is the principle investigator and Co-PI of 14 research projects and supervised several postgraduate students. He is an expert in measuring the optical and electrical properties of nanomaterials using different techniques. He has vast experience in nanoparticles synthesis and sensors� fabrication for detecting hazardous gasses. Dr. Mohammed A. Al-Meetani has received his PhD Degree in applied analytical chemistry from Colorado School of Mines, Colorado, USA in 2003. His research encompasses various topics in the areas of pyrolysis mass spectrometry of the peptide and proteins, degradation of organic water pollutants using advanced oxidation processes, determination of human derived chemicals in ground and wastewater, and development of analytical methods for detection and determination of designer drugs of abuse. Dr. Meetani�s work has resulted over 40 articles in reputed journals and international conference proceedings. He has worked at different international universities and research institutes such as national renewable energy laboratory (NREL), CO, USA, University of Wyoming, Wy, USA, and Sam�s Nobel Foundation, OK, USA. Saeed Tariq received his M.Sc. and M.Phil. degrees in 1992 and 1994 respectively from Biological Department of Quaid-E-Azam University, Islamabad, Pakistan (Title of the thesis: Electron Microscopic studies of adrenal gland in an animal model) and obtained Ph.D. degree in Pharmaceutical Sciences from the Department of Pharmacodynamics Semmelweis University, Budapest, Hungary in 2016 (Thesis with title: Distribution of nociception (a neuropeptide) in the pancreas and uterus of normal and diabetic rats: An electron microscopic studies). In the Department of Biological Sciences, Quaid- E-Azam University Islamabad he was working as teaching and research associate till 2001 and was also In-charge of Electron microscopy facility. In 2001 he joined as a Medical Research Specialist and In-charge Electron & Confocal Microscopy Facility, Anatomy Department, Faculty of Medicine and Health Science, UAE University Alain, UAE. His publication record includes about 50 publications. He has intensive experience in studying the conventional ultra-structural morphology and immune electron microscopy using immunogold labeling and other various techniques in the field of Transmission and Scanning Electron microscopy. He has been involved in different ongoing research projects of various disciplines of Biological and Material Sciences from CMHS, and UAEU faculty and students for teaching and research purposes. He was honored with an Award of Excellence and recognized as a best employee of the Year 2010 from the Faculty of Medicine and Health Science, UAEU. Dr. Ayesh received his PhD in Physics (Nanotechnology) in 2007 from Physics and Astronomy Department, University of Canterbury, Christchurch - New Zealand. His PhD thesis title is �Device fabrication using Bi nanoclusters�. Currently, he is an associate professor with the Department of Mathematics, Statistics and Physics, Qatar University, Doha, Qatar. Dr. Ayesh is the leader of Nanocluster Devices research group, and he is an active scholar in interdisciplinary research that involves design of materials and their applications. His publication record includes about 70 publications and several international patents. He is the principle investigator of several running projects, and a supervisor of many PhD and MSC candidates. Dr. Ayesh is expert in device fabrication, nanomaterial synthesis, and characterization. He is expert in the nano- and micro- device fabrication using both the top-down and bottom-up approaches as well as the self-assembly of the nanostructure within the device. Furthermore, he is expert in nanocluster fabrication using physical methods. He has intensive experience in studying the carrier transport, morphology, nanocluster-nanocluster interaction, and nanocluster-surface interaction for the fabricated devices using different techniques such as: AC and DC electrical measurements, Hall effect measurements, FE-SEM imaging, AFM imaging, and TEM imaging.Scopu