44 research outputs found
SWIR Emissive RosIndolizine Dyes With Nanoencapsulation In Water Soluble Dendrimers
Shortwave infrared (SWIR) emission has great potential for deep-tissue in vivo biological imaging with high resolution. In this article, the synthesis and characterization of two new xanthene-based RosIndolizine dyes coded PhRosIndz and tolRosIndz is presented. The dyes are characterized via femtosecond transient absorption spectroscopy as well as steady-state absorption and emission spectroscopies. The emission of these dyes is shown in the SWIR region with peak emission at 1097 nm. TolRosIndz was encapsulated with an amphiphilic linear dendritic block co-polymer (LDBC) coded 10-PhPCL-G3 with high uptake yield. Further, cellular toxicity was examined in vitro using HEK (human embryonic kidney) cells where a \u3e90% cell viability was observed at practical concentrations of the encapsulated dye which indicates low toxicity and reasonable biocompatibility
Reference enthalpy method developed from solutions of the boundary-layer equations
A simple average of local enthalpy over the velocity profile is proposed as the proper definition of reference enthalpy for the purpose of quasi-one-dimensional treatment of compressible boundary layers. Use of Van Driest's nearly exact solutions of the laminar boundary-layer equations shows that this definition produces Eckert's reference enthalpy formulation for the special case of an adiabatic wall. For surfaces other than adiabatic, either Eckert's form should be replaced by that of Young and Janssen, or the coefficient in Eckert's viscous heating term should be slightly modified. A similar analysis was conducted for turbulent flows using Whitfield and High's simplified solutions of the turbulent boundary-layer equations. Dorrance's derivation of reference quantities is also addressed. This work provides a theoretical basis for the empirical reference enthalpy formulas of Eckert and others and supplies practical expressions for the reference enthalpy of both laminar and turbulent compressible boundary layers
Left Hemisphere Specialization for Oro-Facial Movements of Learned Vocal Signals by Captive Chimpanzees
The left hemisphere of the human brain is dominant in the production of speech and signed language. Whether similar lateralization of function for communicative signal production is present in other primates remains a topic of considerable debate. In the current study, we examined whether oro-facial movements associated with the production of learned attention-getting sounds are differentially lateralized compared to facial expressions associated with the production of species-typical emotional vocalizations in chimpanzees.Still images captured from digital video were used to quantify oro-facial asymmetries in the production of two attention-getting sounds and two species-typical vocalizations in a sample of captive chimpanzees. Comparisons of mouth asymmetries during production of these sounds revealed significant rightward biased asymmetries for the attention-getting sounds and significant leftward biased asymmetries for the species-typical sounds.These results suggest that the motor control of oro-facial movements associated with the production of learned sounds is lateralized to the left hemisphere in chimpanzees. Furthermore, the findings suggest that the antecedents for lateralization of human speech may have been present in the common ancestor of chimpanzees and humans approximately 5 mya and are not unique to the human lineage
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
Synthesis and Compatibility of Ionic Liquid Containing Rod-Coil Polyimide Gel Electrolytes with Lithium Metal Electrodes
A highly cross-linked polyimide-polyethylene oxide copolymer has been synthesized that is capable of holding large volumes of liquid component, simultaneously maintaining good dimensional stability. An amine end capped oligomer was made that was imidized in solution, followed by reaction with a triisocyanate in the presence of desired additives at ambient temperature. Polymer films are able to hold over 4 times their weight in room temperature ionic liquid RTIL or carbonate solvent. Electrolytes were studied that contained varying amounts of RTIL, lithium trifluoromethanesulfonimide LiTFSi, and alumina nanoparticles. Electrochemical stability of these electrolytes with lithium metal electrodes was studied by galvanic cycling and impedance spectroscopy. Improved cycling stability and decreased interfacial resistance were observed when increasing amounts of RTIL and LiTFSi were added. The addition of small amounts of alumina further decreased interfacial resistance by nearly an order of magnitude. During the course of the study, cycling stability increased from less than 3 to greater than 1000 h at 60 C and 0.25 mA/cm2 current density
Chaplaincy and Mental Health in the Department of Veterans Affairs and Department of Defense
Chaplains play important roles in caring for Veterans and Service members with mental health problems. As part of the Department of Veterans Affairs (VA) and Department of Defense (DoD) Integrated Mental Health Strategy, we used a sequential approach to examining intersections between chaplaincy and mental health by gathering and building upon: (1) input from key subject matter experts; (2) quantitative data from the VA/DoD Chaplain Survey (N = 2,163; response rate of 75% in VA and 60% in DoD); and (3) qualitative data from site visits to 33 VA and DoD facilities. Findings indicate that chaplains are extensively involved in caring for individuals with mental health problems, yet integration between mental health and chaplaincy is frequently limited due to difficulties between the disciplines in establishing familiarity and trust. We present recommendations for improving integration of services, and we suggest key domains for future research
Water-Soluble NIR Absorbing and Emitting Indolizine Cyanine and Indolizine Squarine Dyes for Biological Imaging
Organic dyes that absorb and emit in the near-infrared (NIR) region are potentially noninvasive, high-resolution, and rapid biological imaging materials. Indolizine donor-based cyanine and squaraine dyes with water-solubilizing sulfonate groups were targeted in this study due to strong absorptions and emissions in the NIR region. As previously observed for nonwater-soluble derivatives, the indolizine group with water-solubilizing groups retains a substantial shift toward longer wavelengths for both absorption and emission with squaraines and cyanines relative to classically researched indoline donor analogues. Very high quantum yields (as much as 58%) have been observed with absorption and emission \u3e700 nm in fetal bovine serum. Photostability studies, cell culture cytotoxicity, and cell uptake specificity profiles were all studied for these dyes, demonstrating exceptional biological imaging suitability
Molecular Switch Cobalt Redox Shuttle with a Tunable Hexadentate Ligand
Strong-field hexadentate ligands were synthesized and
coordinated
to cobalt metal centers to result in three new low-spin to low-spin
Co(III/II) redox couples. The ligand backbone has been modified with
dimethyl amine groups to result in redox potential tuning of the Co(III/II)
redox couples from −200 to −430 mV versus Fc+/0. The redox couples surprisingly undergo a reversible molecular switch
rearrangement from five-coordinate Co(II) to six-coordinate Co(III)
despite the ligands being hexadentate. The complexes exhibit modestly
faster electron self-exchange rate constants of 2.2–4.2 M–1 s–1 compared to the high-spin to
low-spin redox couple [Co(bpy)3]3+/2+ at 0.27
M–1 s–1, which is attributed to
the change in spin state being somewhat offset by this coordination
switching behavior. The complexes were utilized as redox shuttles
in dye-sensitized solar cells with the near-IR AP25 + D35 dye system and exhibited improved photocurrents over the
[Co(bpy)3]3+/2+ redox shuttle (19.8 vs 18.0
mA/cm2). Future directions point toward pairing the low-spin
to low-spin Co(II/III) tunable series to dyes with significantly more
negative highest occupied molecular orbital potentials that absorb
into the near-IR where outer sphere redox shuttles have failed to
produce efficient dye regeneration
Ultra Bright Near‐Infrared Sulfonate‐Indolizine Cyanine‐ and Squaraine‐Albumin Chaperones: Record Quantum Yields and Applications
The design of bright, high quantum yield (QY) materials in the near-infrared (NIR) spectral region in water remains a significant challenge. A series of cyanine and squaraine dyes varying water solubilizing groups and heterocycles are studied to probe the interactions of these groups with albumin in water. Unprecedented, \u27ultra bright\u27 emission in water is observed for a sulfonate indolizine squaraine dye (61.1% QY) and a sulfonate indolizine cyanine dye (46.7% QY) at NIR wavelengths of \u3e700 nm and \u3e800 nm, respectively. The dyes presented herein have a lower limit of detection than the most sensitive dyes known in the NIR region for albumin detection by at least an order of magnitude, which enables more sensitive diagnostic testing. Additionally, biotinylated human serum albumin complexed with the dyes reported herein was observed to function as an immunohistochemical reagent enabling high resolution imaging of cellular α-tubulin at low dye concentrations