Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

Functionalization and fabrication of single-walled carbon nanotube-based chemiresistors for sensory applications

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, 2015.Vita. Cataloged from PDF version of thesis.Includes bibliographical references.Chemical sensors that identify and monitor volatile organic compounds (VOCs) have an important role in assessing public security, food and water quality, industrial environment, and health. The fabrication of carbon-based sensors by printing, dip coating, drop casting, or drawing has advantages of being simple and low-cost without the need for highly specialized facilities. We have investigated the fabrication of sensors both by drop casting and drawing. Single-walled carbon nanotubes (SWCNT) electronic and spectroscopic properties for sensory applications are described. SWCNTs have unique properties wherein their conductance can be altered by environmental effects. These carbon nanomaterials can be easily integrated into a chemiresitive device to detect various analytes. In our studies using the drop cast method, we noncovalently functionalized SWCNT with a trifunctional selector that has three important properties: it noncovalently functionalizes SWCNTs with cofacial n-n interactions, it binds to cyclohexanone (a target analyte for explosive detection) via hydrogen bond, and it improves the overall robustness of SWCNT-based chemiresistors (e.g., humidity and heat). In our other studies, we fabricated sensors by drawing. Abrasion is a safe, simple, solvent-free, and low cost method for deposition of carbon-based materials onto a substrate. We successfully demonstrated fabrication on a wide variety of substrates (e.g., weighing paper, polymethyl methacrylate, silicon, and adhesive tape) of fully-drawn chemical sensors on a chip that can detect in real time parts-per-million (ppm) quantities of various vapors using SWCNTs as sensing materials and graphite as electrodes. This fabrication methodology does not require specialized facilities (e.g., clean room, thermal evaporator) and can be performed entirely on a desktop (with appropriate ventilation and safety precautions for handling nanomaterials). We also extended the abrasion method to detect anions such as fluoride (use to manufacture nuclear weapons) and cyanide (chemical warfare agent). These sensor are highly sensitive detecting the United State Environmental Protection Agency (EPA) maximum contaminant level (MCL) of fluoride and cyanide selectively.by Kelvin Mitchell Frazier.Ph. D

Robust Cyclohexanone Selective Chemiresistors Based on Single-Walled Carbon Nanotubes

Functionalized single-walled carbon nanotube (SWCNT)-based chemiresistors are reported for a highly robust and sensitive gas sensor to selectively detect cyclohexanone, a target analyte for explosive detection. The trifunctional selector has three important properties: it noncovalently functionalizes SWCNTs with cofacial π–π interactions, it binds to cyclohexanone via hydrogen bond (mechanistic studies were investigated), and it improves the overall robustness of SWCNT-based chemiresistors (e.g., humidity and heat). Our sensors produced reversible and reproducible responses in less than 30 s to 10 ppm of cyclohexanone and displayed an average theoretical limit of detection (LOD) of 5 ppm.Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies (W911NF-13-D-0001

Fully-drawn carbon-based chemical sensors on organic and inorganic surfaces

Mechanical abrasion is an extremely simple, rapid, and low-cost method for deposition of carbon-based materials onto a substrate. However, the method is limited in throughput, precision, and surface compatibility for drawing conductive pathways. Selective patterning of surfaces using laser-etching can facilitate substantial improvements to address these current limitations for the abrasive deposition of carbon-based materials. This study demonstrates the successful on-demand fabrication of fully-drawn chemical sensors on a wide variety of substrates (e.g., weighing paper, polymethyl methacrylate, silicon, and adhesive tape) using single-walled carbon nanotubes (SWCNTs) as sensing materials and graphite as electrodes. Mechanical mixing of SWCNTs with solid or liquid selectors yields sensors that can detect and discriminate parts-per-million (ppm) quantities of various nitrogen-containing vapors (pyridine, aniline, triethylamine).United States. Army Research Office. Institute for Soldier NanotechnologiesUnited States. Defense Advanced Research Projects AgencyNational Institutes of Health (U.S.) (Ruth L. Kirschstein National Research Service Award F32CA157197)National Cancer Institute (U.S.