Extrapolation of single particle soot photometer incandescent signal data

The Single Particle Soot Photometer (SP2) is an instrument for quantifying the refractory black carbon (rBC) mass of individual aerosol particles. It heats the particle’s rBC component to vaporization and quantifies the resulting visible thermal radiation to infer rBC mass. For purely technical reasons, SP2s are unable to quantify rBC mass beyond an easily adjustable limit due to eventual saturation of the electronics that record the visible light signals. Here, we evaluate an extrapolation algorithm to estimate rBC masses exceeding this upper limit in an SP2. The algorithm is based on identifying the crossing points of linear fits to unsaturated data, and using the duration of the saturated data to constrain potential errors. We find that extrapolation performance is quite insensitive to instrument parameters including laser intensity, rate of data acquisition, and particle speed through the laser. However, this approach increases uncertainty on the detection limit of the instrument, and is hence only useful in unknown aerosols for very limited extrapolation to approximately a factor of 1.5 increase in the upper mass range, corresponding to a 15% increase in the upper diameter limit. This increased range small enough that early identification of meaningful saturation during measurement campaigns remains the only tenable approach to robustly characterizing rBC mass size distributions and, in some cases, rBC mass concentrations.     

Crystallization kinetics of low‐density polyethylene and polypropylene melt‐blended with a low‐Tg tin‐based phosphate glass

The nonisothermal and isothermal crystallizations of low‐density polyethylene (LDPE) and polypropylene (PP) in phosphate glass (Pglass)–polymer hybrid blends were studied through differential scanning calorimetry (DSC). As the Pglass volume fraction was increased, the percentage crystallinity decreased. The half‐time for crystallization decreased as the propagation rate constant rose, for both of the polymer matrices, with increasing Pglass concentrations. The Pglass was observed to be a nucleating agent for formation of two‐ or three‐dimensional spherulites in the hybrids. Tensile modulus improved for both of the Pglass–polymer hybrids up to 40% Pglass, but the energy to break decreased. Tensile strength changed slightly with the addition of Pglass to the LDPE matrix, exhibiting a larger value than that of pure LDPE at 30%. The tensile strength decreased as more Pglass was added to the PP matrix. The observed differences between tensile properties of the Pglass–PP and Pglass–LDPE hybrids at identical Pglass volume concentration were found to be consistent with that of the crystallization behavior of the hybrids. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3445–3456, 2003     

Effect of ionic content,solid content,degree of neutralization,and chain extension on aqueous polyurethane dispersions prepared by prepolymer method

There are many variables in the preparation of aqueous polyurethane (PU) dispersions. Carboxylic acid content, solid content, degree of pre/postneutralization of the carboxylic acids, and chain extension all impact dispersion particle size, viscosity, pH, molecular weights, and glass transition temperature. This study evaluated the impact of these variables on a given PU dispersion formulation prepared from isophorone diisocyanate, an aliphatic polyester polyol, dimethylol propionic acid, and hexamethylene diamine with triethyl amine as the neutralizing base and N‐methyl pyrrolidone as the cosolvent. Changes in carboxylic acid content, degree of preneutralization, and chain extension were found to have the expected impacts on dispersions properties. Increased ionic content in the dispersion step led to lower particle size and higher viscosity, increased chain extension with its concurrent increase in molecular improved subsequent film properties. Surprising results were obtained by varying the amount of postneutralization and from increased solids content at the time of dispersion. Unexpectedly, both of these variations led to much higher dispersion viscosities and particle size in solution. To have these changes take place, it is theorized that there is a major change in solution morphology caused by these modifications. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2514–2520, 2005     

Improved additive manufacturing of silicon carbide parts via pressureless electric field-assisted sintering

High solids loading silicon carbide (SiC)-based aqueous slurries containing only .5 wt. % organic additives were utilized to create specimens of various geometries via an extrusion-based additive manufacturing (AM) technique. Pressureless electric field-assisted sintering was performed to densify each specimen without deformation. The combination of these techniques produced parts with >98% relative density despite containing only 5 wt.% oxide sintering additives. After sintering, specimens contained only the α-SiC and yttrium aluminum perovskite phases. This suggests the evolution of a nonequilibrium yttrium aluminate phase, as well as transformation from β-SiC to α-SiC. The fabrication method presented in this work has advantages over other AM techniques commonly used with SiC, because it does not require significant organic additives nor additional postprocessing steps such as chemical vapor infiltration or polymer impregnation and pyrolysis.     

Glass with hydration-induced compressive stress profiles

A novel potassium phospho-aluminosilicate composition is described that can be strengthened by water vapor to achieve deep compressive stress (CS) profiles. Water vapor treatment at (A) 85°C and 85% relative humidity for 40 days results in a CS of 389 ± 20 MPa and a compressive depth of layer (DOL) of 18 ± 2 μm. When treated at (B) 160°C and 0.1 MPa for 7 days, a CS of 245 ± 20 MPa and a DOL of 40 ± 2 μm is achieved. Glasses with hydration-induced stress profiles can provide high retained strength following flaw introduction compared with ion-exchanged soda-lime silicate glass. Sample treatment B also has an exemplary Vickers indentation cracking threshold value greater than 20 kgf. The hydration profile determined by secondary ion mass spectrometry (SIMS) is shown to closely match the stress profile for these samples. SIMS analysis also shows that the depth of water enrichment correlates well with the depletion depth of phosphorus. The high tendency towards water-induced strengthening for this new type of glass even enables self-strengthening by the generation of a near-surface CS profile following exposure to ambient conditions.     

The Role of α1-Adrenoceptor Antagonists in the Treatment of Prostate and Other Cancers

This review evaluates the role of α-adrenoceptor antagonists as a potential treatment of prostate cancer (PCa). Cochrane, Google Scholar and Pubmed were accessed to retrieve sixty-two articles for analysis. In vitro studies demonstrate that doxazosin, prazosin and terazosin (quinazoline α-antagonists) induce apoptosis, decrease cell growth, and proliferation in PC-3, LNCaP and DU-145 cell lines. Similarly, the piperazine based naftopidil induced cell cycle arrest and death in LNCaP-E9 cell lines. In contrast, sulphonamide based tamsulosin did not exhibit these effects. In vivo data was consistent with in vitro findings as the quinazoline based α-antagonists prevented angiogenesis and decreased tumour mass in mice models of PCa. Mechanistically the cytotoxic and antitumor effects of the α-antagonists appear largely independent of α 1-blockade. The proposed targets include: VEGF, EGFR, HER2/Neu, caspase 8/3, topoisomerase 1 and other mitochondrial apoptotic inducing factors. These cytotoxic effects could not be evaluated in human studies as prospective trial data is lacking. However, retrospective studies show a decreased incidence of PCa in males exposed to α-antagonists. As human data evaluating the use of α-antagonists as treatments are lacking; well designed, prospective clinical trials are needed to conclusively demonstrate the anticancer properties of quinazoline based α-antagonists in PCa and other cancers.     

Nanostructured polymer blends: Synthesis and structure

Nanostructured polymer blends prepared via anionic ring opening polymerizations of cyclic monomers in the presence of a pre-made polymer melt exhibit a number of special properties over traditional polymer blends and homopolymers. Here, we report on a simple and versatile method of in situ polymerization of macrocyclic carbonates in the presence of a maleic anhydride polypropylene (mPP) matrix and a surface-active compatibilizer (i.e. PC grafted onto a mPP backbone generated in situ) to yield a micro- and nanostructured polymer blends consisting of a polycarbonate (PC) minor phase, and a polypropylene (PP) major phase. By varying the processing conditions and concentration of the macrocyclic carbonate it was possible to reduce the size of the PC dispersions to an average minor diameter of 150 nm. NMR and TEM characterizations indicate that the PC dispersions do not influence crystal content in the PP phase. Overall, the results point to a simple strategy and versatile route to new polymeric materials with enhanced benefits.     

SCR deactivation in a full-scale cofired utility boiler

The Energy and Environmental Research Center installed a portable slipstream selective catalytic reduction (SCR) reactor in the convective pass of a utility boiler cofiring wood waste and Powder River Basin (PRB) coal. Catalyst sections were removed after 43, 128, and 171 days of operation. SCR catalytic activity was determined for each section, and a sample of one section was examined under a scanning electron microscope to look for signs of catalyst blinding and/or poisoning. The catalyst deactivated at an apparently inverse rate with an initial deactivation rate of 18% every 1000 h. The major mode of deactivation appeared to be pore blocking by combined alkali and calcium sulfate deposition and growth.     

Non-Coding RNAs Set a New Phenotypic Frontier in Prostate Cancer Metastasis and Resistance

Prostate cancer (PCa) mortality remains a significant public health problem, as advanced disease has poor survivability due to the development of resistance in response to both standard and novel therapeutic interventions. Therapeutic resistance is a multifaceted problem involving the interplay of a number of biological mechanisms including genetic, signaling, and phenotypic alterations, compounded by the contributions of a tumor microenvironment that supports tumor growth, invasiveness, and metastasis. The androgen receptor (AR) is a primary regulator of prostate cell growth, response and maintenance, and the target of most standard PCa therapies designed to inhibit AR from interacting with androgens, its native ligands. As such, AR remains the main driver of therapeutic response in patients with metastatic castration-resistant prostate cancer (mCRPC). While androgen deprivation therapy (ADT), in combination with microtubule-targeting taxane chemotherapy, offers survival benefits in patients with mCRPC, therapeutic resistance invariably develops, leading to lethal disease. Understanding the mechanisms underlying resistance is critical to improving therapeutic outcomes and also to the development of biomarker signatures of predictive value. The interconversions between epithelial-to-mesenchymal transition (EMT) and mesenchymal-to-epithelial transition (MET) navigate the prostate tumor therapeutic response, and provide a novel targeting platform in overcoming therapeutic resistance. Both microRNA (miRNA)- and long non-coding RNA (lncRNA)-mediated mechanisms have been associated with epigenetic changes in prostate cancer. This review discusses the current evidence-based knowledge of the role of the phenotypic transitions and novel molecular determinants (non-coding RNAs) as contributors to the emergence of therapeutic resistance and metastasis and their integrated predictive value in prostate cancer progression to advanced disease.