Chemical Engineering

Prodiginines, which are tripyrrole alkaloids displaying a wide array of bioactivities, occur as linear and cyclic congeners. Identification of an unclustered biosynthetic gene led to the discovery of the enzyme responsible for catalyzing the regiospecific C-H activation and cyclization of prodigiosin to cycloprodigiosin in Pseudoalteromonas rubra. This enzyme is related to alkylglycerol monooxygenase and unrelated to RedG, the Rieske oxygenase that produces cyclized prodiginines in Streptomyces, implying convergent evolution.

Antibody detection assays are essential for evaluating immunity of individuals against a given virus, and this has been particularly relevant during the COVID‐19 pandemic. Current serology assays either require a laboratory setting and take >1 hr (i.e., enzyme‐linked immunosorbent assay [ELISA]) or are rapid but only qualitative in nature and cannot accurately track antibody levels over time (i.e., lateral flow assay [LFA]). Therefore, there is a need for development of a rapid and simple but also quantitative assay that can evaluate antibody levels in patients accurately over time. We have developed an assay that uses a split nanoluciferase fused to the spike or nucleocapsid proteins of the SARS‐CoV‐2 virus to enable luminescent‐based detection of spike‐ or nucleocapsid‐binding antibodies in serum, plasma, and whole blood samples. The resulting approach is simple, rapid, and quantitative and is highly amenable to low‐/medium‐throughput scale using plate‐based assays, high‐throughput scale using robotics, and point‐of‐care applications. In this article, we describe how to perform the assay in a laboratory setting using a plate reader or liquid‐handling robotics and in a point‐of‐care setting using a handheld, battery‐powered luminometer. Together, these assays allow antibody detection to be easily performed in multiple settings by simplifying and reducing assay time in a laboratory or clinical environment and by allowing for antibody detection in point‐of‐care, nonlaboratory settings. © 2022 Wiley Periodicals LLC. Basic Protocol: SARS‐CoV‐2 antibody detection using the split‐luciferase assay on a medium‐throughput scale with a laboratory luminometer Alternate Protocol 1: High‐throughput‐based protocol for SARS‐CoV‐2 antibody detection using a robotic platform Alternate Protocol 2: Point‐of‐care‐based protocol for SARS‐CoV‐2 antibody detection using a handheld luminometer Support Protocol: Determining positive/negative cutoffs for test samples and standardizing the assay between days

Metal−organic frameworks (MOFs) have received attention for a myriad of potential applications including catalysis, gas storage, and gas separation. Coordinatively unsaturated metal ions often enable key functional behavior of these materials. Most commonly, MOFs have been metalated from the condensed phase (i.e., from solution). Here we introduce a new synthetic strategy capable of metallating MOFs from the gas phase: atomic layer deposition (ALD). Key to enabling metalation by ALD In MOFs (AIM) was the synthesis of NU-1000, a new, thermally stable, Zr-based MOF with spatially oriented −OH groups and large 1D mesopores and apertures.

The absorption efficiency Q a is calculated using Mathematica 5 according to Mie scattering solutions to Maxwell's equations for an infinite dielectric cylinder. 1 Specifically by conservation of energy, Q a = Q e − Q s , where Q e and Q s are the extinction and scattering efficiencies, respectively. Common derivative relations for both Bessel and Hankel functions were used 2 and summations were carried up to n = 10, above which no significant changes in the dependence of Q a on diameter

The development of passivated silicon nanowire (SiNW) based micro-supercapacitor electrodes for on-chip applications using an environmentally benign aqueous electrolyte is reported. The SiNWs, produced by low-temperature (50 C) electrochemical etching, corrode during charge/discharge cycling in the aqueous environment, but upon coating with a silicon carbide passivation layer, the corrosion is mitigated. The as-formed materials are in electrical contact with the substrate, requiring no additional current collector. The passivated NWs achieve capacitance values up to $1.7 mF/cm 2 projected area (comparable to state-of-the art carbon based micro-supercapacitor electrodes), exhibit robust cycling stability, and maintain capacitive behavior over a wide range of charge/discharge rates. V

Electrical contact to silicon carbide with low contact resistivity and high stability is a critical requirement for SiC-based microsystem and nanosystem technology for harsh environment applications. In this letter, nanocrystalline graphitic carbon is grown at the interface between SiC and Pt to lower the Ohmic contact resistivity and enhance the stability of Pt contacts to polycrystalline 3C-SiC operated at elevated temperatures. Analysis shows that reduced barrier height, oxide-free surface, reduced density of vacancy defects, and suppressed reactivity between Pt and SiC are likely responsible for the reduced Ohmic contact resistivity and high thermal stability of Pt contacts to graphitized SiC.

Strain state of ultrathin InAs-on-insulator layers obtained from an epitaxial transfer process is studied. The as-grown InAs epilayer ͑10-20 nm thick͒ on the GaSb/AlGaSb source wafer has the expected ϳ0.62% tensile strain. The strain is found to fully release during the epitaxial transfer of the InAs layer onto a Si/ SiO 2 substrate. In order to engineer the strain of the transferred InAs layers, a ZrO x cap was used during the transfer process to effectively preserve the strain. The work presents an important advance toward the control of materials properties of III-V on insulator layers.

The evolution in the surface morphology of epitaxial graphene films and 6H-SiC(0001) substrates is studied by electron channeling contrast imaging. Whereas film thickness is determined by growth temperature only, increasing growth times at constant temperature affect both internal stress and film morphology. Annealing times in excess of 8-10 minutes lead to an increase in the mean square roughness of SiC step edges to which graphene films are pinned, resulting in compressively stressed films at room temperature. Shorter annealing times produce minimal changes in the morphology of the terrace edges and result in nearly stress-free films upon cooling to room temperature.

Disilabutane is used as a single-source precursor to deposit conformal silicon-carbide films on silicon atomic-force-microscopy cantilevers. By measuring the resonance frequency of the cantilever as a function of silicon-carbide film thickness and developing an appropriate model, the value of the film's elastic modulus is determined. This value is in good agreement with those reported for silicon-carbide films deposited using conventional dual-source chemical-vapor deposition. Additionally, we comment on the feasibility of integrating this process into the fabrication technology for microelectromechanical systems.

Laser irradiation can incur spatially confined and rapid heating that enables precisely controlled nucleation and subsequent growth of nanomaterials. This localization of the laser-driven growth can realize on-demand, direct synthesis of nanowires composed of multiple elements on a single platform. In this study, silicon and germanium nanowires are grown by laser-induced vapor-liquid-solid mechanism in a hetero-array configuration by simply switching the reactant gas precursors as the growth of nanowires is limited within the heat-affected zone induced by the laser. Energy dispersive x-ray and Raman spectroscopies were performed to observe the elemental composition and crystallinity of as-grown nanowires, respectively. V

Atomic force microscopy has been used to characterize the mechanical elasticity of Si nanowires synthesized by the vapor-liquid-solid method. The nanowires are horizontally grown between the two facing Si͑111͒ sidewalls of microtrenches prefabricated on a Si͑110͒ substrate, resulting in suspended single and double clamped nanowire-in-trench structures. The deflection of the nanowires is induced and measured by the controlled application of normal forces with the microscope tip. The observed reversibility of the nanowire deflections and the agreement between the measured deflection profiles and the theoretical behavior of single and double clamped elastic beams demonstrate the overall beamlike mechanical behavior and the mechanical rigidity of the clamping ends of the nanowire-in-trench structures. These results demonstrate the potential of the nanowire-in-trench fabrication approach for the integration of VLS grown nanostructures into functional nanomechanical devices.

Adhesion or stiction is a key problem in surface micromachining technology, affecting the reliability of most MEMS. To date, the quantitative analysis of the phenomenon has been limited to in-plane adhesion. Since many micromechanisms involve contacts between sidewalls, we have designed a microinstrument to measure sidewall adhesion. Here, we describe the design, modeling, results and problems encountered with this first generation of sidewall adhesion devices.

Photoresist, which is frequently used in existing microelectronics processing, can be pyrolyzed to form a conductive carbon film. We demonstrate a pyrolysis technique of SPR-220 photoresist, which consists of heating in Ar ambient to 900 °C followed by further annealing in an H 2 /Ar mixture, and results in a high surface area porous carbon which is applicable to supercapacitor electrode fabrication. Electrochemical testing of the pyrolyzed photoresist film yields a specific areal capacitance of 1.5-3.5 mF/cm 2 and a specific volumetric capacitance of 15-35 F/cm 3. These results are obtained on the aspyrolyzed films, without additional activation or deposition of electroactive species. The cycling stability of the films is shown to be robust over 10,000 cycles. This photoresist pyrolysis process could be readily integrated into microelectromechanical systems or microelectronics technology for on-chip energy storage.

Porous anodic alumina (PAA) masks are employed for the template synthesis of high density silicon nanowire (SiNW) arrays on a silicon substrate by the vapor-liquid-solid method. The uniform-sized ordered arrays of nanopores in the PAA mask anchored to Si(111) substrate are shown to enable the realization of vertically aligned epitaxial SiNWs with uniform diameter and spacing. The average diameter of the wires is 72 nm while the density is 60 wires/µm 2 . The high packing density and tightly controlled dimensions of SiNWs obtained by this nonlithographic method allow their effective integration into nanodevices for mass production.