Multiplexed in-gel microfluidic immunoassays: characterizing protein target loss during reprobing of benzophenone-modified hydrogels.

From whole tissues to single-cell lysate, heterogeneous immunoassays are widely utilized for analysis of protein targets in complex biospecimens. Recently, benzophenone-functionalized hydrogel scaffolds have been used to immobilize target protein for immunoassay detection with fluorescent antibody probes. In benzophenone-functionalized hydrogels, multiplex target detection occurs via serial rounds of chemical stripping (incubation with sodium-dodecyl-sulfate (SDS) and β-mercaptoethanol at 50-60 °C for ≥1 h), followed by reprobing (interrogation with additional antibody probes). Although benzophenone facilitates covalent immobilization of proteins to the hydrogel, we observe 50% immunoassay signal loss of immobilized protein targets during stripping rounds. Here, we identify and characterize signal loss mechanisms during stripping and reprobing. We posit that loss of immobilized target is responsible for ≥50% of immunoassay signal loss, and that target loss is attributable to disruption of protein immobilization by denaturing detergents (SDS) and incubation at elevated temperatures. Furthermore, our study suggests that protein losses under non-denaturing conditions are more sensitive to protein structure (i.e., hydrodynamic radius), than to molecular mass (size). We formulate design guidance for multiplexed in-gel immunoassays, including that low-abundance proteins be immunoprobed first, even when targets are covalently immobilized to the gel. We also recommend careful scrutiny of the order of proteins targets detected via multiple immunoprobing cycles, based on the protein immobilization buffer composition

Evaluation and demonstration of the use of cryogenic propellants /oxygen/hydrogen/ for reaction control systems. Volume 2 - Experimental evaluations and demonstration Final report

Evaluation and demonstration of cryogenic propellant /oxygen-hydrogen/ use for spacecraft reaction control system

Rooted in History: Historic Preservation as a Foundation for Community Engagement Along the Lower Schuylkill

Once the centerpiece of a rolling pastoral landscape, punctuated by some of the most important ornamental and botanical gardens of the colonial and early national eras, the Lower Schuylkill metamorphosed over the next century into one of the most polluted and environmentally degraded waterways in the country. In this thesis I will discuss the historical, environmental, and political themes that have shaped the evolution of the Lower Schuylkill region. Reviewing analyses and critiques of neoliberal urbanism, particularly in the context of waterfront revitalization projects, I identify ways in which preservation and related fields might support or resist a development-driven agenda. I then consider PIDC’s Lower Schuylkill Master Plan, which outlines a long-term vision for the extension of the Schuylkill river trail, and identify ways in which it fits within the neoliberal framework. Through further analysis of Executive Summaries, Master Plans, Reports, public meeting notes, and other public documents, I discuss how aspects of the Lower Schuylkill Master Plan utilize historic resources to promote a development agenda. I then propose ways in which the preservation of a broad range of resources related to various eras of the region’s history might facilitate deeper community engagement with the space

Octave Spanning Frequency Comb on a Chip

Optical frequency combs have revolutionized the field of frequency metrology within the last decade and have become enabling tools for atomic clocks, gas sensing and astrophysical spectrometer calibration. The rapidly increasing number of applications has heightened interest in more compact comb generators. Optical microresonator based comb generators bear promise in this regard. Critical to their future use as 'frequency markers', is however the absolute frequency stabilization of the optical comb spectrum. A powerful technique for this stabilization is self-referencing, which requires a spectrum that spans a full octave, i.e. a factor of two in frequency. In the case of mode locked lasers, overcoming the limited bandwidth has become possible only with the advent of photonic crystal fibres for supercontinuum generation. Here, we report for the first time the generation of an octave-spanning frequency comb directly from a toroidal microresonator on a silicon chip. The comb spectrum covers the wavelength range from 990 nm to 2170 nm and is retrieved from a continuous wave laser interacting with the modes of an ultra high Q microresonator, without relying on external broadening. Full tunability of the generated frequency comb over a bandwidth exceeding an entire free spectral range is demonstrated. This allows positioning of a frequency comb mode to any desired frequency within the comb bandwidth. The ability to derive octave spanning spectra from microresonator comb generators represents a key step towards achieving a radio-frequency to optical link on a chip, which could unify the fields of metrology with micro- and nano-photonics and enable entirely new devices that bring frequency metrology into a chip scale setting for compact applications such as space based optical clocks