Development of a Technology for Online Measurement of Total and Water-Soluble Copper (Cu) in PM2.5

A novel monitor for online, in situ measurement of copper (Cu) in ambient fine and ultrafine particulate matter (PM) was developed based on a recent published high flow rate aerosol-into-liquid collector. This aerosol-into-liquid collector operates at 200 L/min flow and collects particles directly as highly concentrated slurry samples. The Cu concentration in slurry samples is subsequently determined by a cupric ion selective electrode (ISE). Laboratory tests were conducted to evaluate the performance of the cupric ISE. The calibration curve of the cupric ISE was determined using Cu(NO₃)₂ standard solutions prepared by serial dilution. As part of the evaluation, the effects of ionic strength, temperature and pH of the aerosol slurry sample on the cupric ISE measurement were also evaluated. The Cu measurement system performance was evaluated by collecting and measuring samples of lab-generated Cu(NO₃)₂ aerosols with known mass concentration. Overall, very good agreement between the theoretical and measured Cu concentrations was obtained, corroborating the excellent high overall collection efficiency and measurement accuracy of the Cu measurement system. Field evaluations of the online Cu monitor demonstrated very good agreement for total and water-soluble Cu concentrations with measurements performed by inductively coupled plasma mass spectrometry (ICP-MS), suggesting that interferences from other components of particulate matter are minimal under real world sampling conditions. Moreover, the field tests indicated that the new online Cu monitor could achieve near-continuous collection and measurements (at 2–4 h intervals) for at least 4 to 7 days without any obvious shortcomings in its operation. Both laboratory and field evaluations of the online Cu monitor indicate that it is an effective and valuable technology for PM collection and characterization of Cu in ambient aerosols and provides the foundation for the wider use of ISE for metal analysis and speciation of aerosols.

Copyright 2014 American Association for Aerosol Research     

Comparison of photon transport efficiency in simple scintillation electron detector configurations for scanning electron microscope

The purpose of this paper is to find some general rules for the design of robust scintillation electron detectors for a scanning electron microscope (SEM) that possesses an efficient light-guiding (LG) system. The paper offers some general instructions on how to avoid the improper design of highly inefficient LG configurations of the detectors. Attention was paid to the relevant optical properties of the scintillator, light guide, and other components used in the LG part of the scintillation detector. Utilizing the optical properties of the detector components, 3D Monte Carlo (MC) simulations of photon transport efficiency in the simple scintillation detector configurations were performed using the computer application called SCIUNI to assess shapes and dimensions of the LG part of the detector. The results of the simulation of both base-guided signal (BGS) configurations for SE detection and edge-guided signal (EGS) configurations for BSE detection are presented. It is demonstrated that the BGS configuration with a matted disc scintillator exit side connected to the cylindrical light guide without optical cement is almost always a sufficiently efficient system with a mean LG efficiency of about 20%. It is simulated that poorly designed EGS strip configurations have an extremely low mean LG efficiency of only 0.01%, which can significantly reduce detector performance. On the other hand, no simple nonoptimized EGS configuration with a light guide widening to a circular or square profile, with a polished cemented scintillator and with an indispensable hole in it has a mean LG efficiency lower than 6.5%.     

New crosslinkers for electrospun chitosan fibre mats. I. Chemical analysis

Chitosan (CS), the deacetylated form of chitin, the second most abundant, natural polysaccharide, is attractive for applications in the biomedical field because of its biocompatibility and resorption rates, which are higher than chitin. Crosslinking improves chemical and mechanical stability of CS. Here, we report the successful utilization of a new set of crosslinkers for electrospun CS. Genipin, hexamethylene-1,6-diaminocarboxysulphonate (HDACS) and epichlorohydrin (ECH) have not been previously explored for crosslinking of electrospun CS. In this first part of a two-part publication, we report the morphology, determined by field emission scanning electron microscopy (FESEM), and chemical interactions, determined by Fourier transform infrared microscopy, respectively. FESEM revealed that CS could successfully be electrospun from trifluoroacetic acid with genipin, HDACS and ECH added to the solution. Diameters were 267 ± 199 nm, 644 ± 359 nm and 896 ± 435 nm for CS–genipin, CS–HDACS and CS–ECH, respectively. Short- (15 min) and long-term (72 h) dissolution tests (T₆₀₀) were performed in acidic, neutral and basic pHs (3, 7 and 12). Post-spinning activation by heat and base to enhance crosslinking of CS–HDACS and CS–ECH decreased the fibre diameters and improved the stability. In the second part of this publication, we report the mechanical properties of the fibres.     

Carbon Nanotube–CoF2 Multifunctional Cathode for Lithium Ion Batteries: Effect of Electrolyte on Cycle Stability

Transition metal fluorides (MF_x) offer remarkably high theoretical energy density. However, the low cycling stability, low electrical and ionic conductivity of metal fluorides have severely limited their applications as conversion‐type cathode materials for lithium ion batteries. Here, a scalable and low‐cost strategy is reported on the fabrication of multifunctional cobalt fluoride/carbon nanotube nonwoven fabric nanocomposite, which demonstrates a combination of high capacity (near‐theoretical, ) and excellent mechanical properties. Its strength and modulus of toughness exceed that of many aluminum alloys, cast iron, and other structural materials, fulfilling the use of MF_x‐based materials in batteries with load‐bearing capabilities. In the course of this study, cathode dissolution in conventional electrolytes has been discovered as the main reason that leads to the rapid growth of the solid electrolyte interphase layer and attributes to rapid cell degradation. And such largely overlooked degradation mechanism is overcome by utilizing electrolyte comprising a fluorinated solvent, which forms a protective ionically conductive layer on the cathode and anode surfaces. With this approach, 93% capacity retention is achieved after 200 cycles at the current density of 100 mA g⁻¹ and over 50% after 10 000 cycles at the current density of 1000 mA g⁻¹.     

Influence of Si:Al ratio on the microstructural and mechanical properties of a fine-limestone aggregate alkali-activated slag concrete

Three series of fine limestone aggregate, alkali-activated blast furnace slag (AAS) concretes were fabricated and tested; two through activation with waterglass/NaOH solution, of which one included NaCl as a retarding agent, and one activated by Na₂CO₃. Each of these series was made up of three formulae containing different amounts of Al₂O₃. The compressive strengths of the series activated by waterglass/NaOH after 28 days were ≈65 ± 5.3 MPa, a 22% increase compared to previously reported formulae containing no additional Al₂O₃. Increasing the amount of Al₂O₃ did not further increase strength, however. The Na₂CO₃-activated formulae had strengths of ≈35 ± 3 MPa after 28 days, representing no increase in strength over formulae not containing Al₂O₃ previously reported. X-ray diffraction showed the main binding phase to be calcium silicate hydrate (C–S–H) gel, as is commonly found in ordinary Portland cement (OPC). Fourier transform infrared spectroscopy showed little difference from the previously reported results for formulae not containing Al₂O₃ and strongly resemble the spectra reported elsewhere for C–S–H. Electron microscopy, coupled with energy dispersive spectroscopy, showed the cementing phase to be a single homogenous phase—not a mixed system of geopolymer and C–S–H gel—with a lower volume fraction of unreacted slag than formulae without Al₂O₃. The reason for the increase in strength of Al₂O₃-containing formulae is unclear, but is unlikely to be ascribed to the formation of large amounts of ‘geopolymers’ and may be related to a possible increase in reaction temperature of between 2 and 5°C, depending on amount of additive.     

Pulmonary endodermal tumor resembling fetal lung: report of a case in a 14-year-old girl

This report describes the clinical and histologic features of a pulmonary tumor in a 14-year-old girl that is most consistent with a rare entity described in the literature as "pulmonary endodermal tumor resembling fetal lung" (PET). This tumor is composed of glycogen-rich columnar cells forming complex glands with focal festooning and mitotic activity, admixed with solid "morules" of cells with eosinophilic cytoplasm and focal nuclear clearing. Patchy tumor necrosis and a bland stroma were also present. Immunoreactivity for carcinoembryonic antigen (CEA), alpha 1-antichymotrypsin, and 12E7 was present in glandular cells and for human chorionic gondatropin (HCG), alpha 1-antichymotrypsin, and 12E7 in morular cells. Ultrastructural features are those of an epithelial tumor. Related entities have been called "pulmonary blastoma lacking sarcomatous elements" and "adenocarcinoma of fetal lung type." Most cases of PET have occurred in adults, and the histologic features thought to have prognostic significance in small published series are applied to our case, in which the patient remains well and without evidence of tumor recurrence or metastasis for 28 months following local resection as the sole treatment.     

A Comparison of Narrative Exposure Therapy, Supportive Counseling, and Psychoeducation for Treating Posttraumatic Stress Disorder in an African Refugee Settlement.

Little is known about the usefulness of psychotherapeutic approaches for traumatized refugees who continue to live in dangerous conditions. Narrative exposure therapy (NET) is a short-term approach based on cognitive-behavioral therapy and testimony therapy. The efficacy of narrative exposure therapy was evaluated in a randomized controlled trial. Sudanese refugees living in a Ugandan refugee settlement (N = 43) who were diagnosed as suffering from posttraumatic stress disorder (PTSD) either received 4 sessions of NET, 4 sessions of supportive counseling (SC), or psychoeducation (PE) completed in 1 session. One year after treatment, only 29% of the NET participants but 79% of the SC group and 80% of the PE group still fulfilled PTSD criteria. These results indicate that NET is a promising approach for the treatment of PTSD for refugees living in unsafe conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychologists: Obligated or Entitled?

This column looks at professional psychology's lack of a sense of obligation, the expectation that we owe society something sans remuneration. The field appears to be embracing and promulgating an attitude of entitlement, that is, society owes us a good, secure existence. As professionals in psychology we are specifically skilled and should be properly compensated; how much we earn is not an issue. The problem is an increasing failure to see an obligation to return something to society without foreseeable personal or financial gain. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characterization of the enzymatic 7-O-acetylation of sialic acids and evidence for enzymatic O-acetyl migration from C-7 to C-9 in bovine submandibular gland

BACKGROUND: Although the anticancer effects of progesterone therapy for patients with endometrial carcinoma are widely acknowledged, a detailed assessment of the resultant morphologic alterations in tumor tissue kinetics has hitherto been lacking. METHODS: Biopsy and hysterectomy specimens of 14 endometrial carcinomas (endometrioid-type) before and during progesterone therapy were studied to clarify changes in apoptosis and cell proliferation and their relation to morphologic alterations. The extent of squamous differentiation within tumor lesions was also examined. RESULTS: In the good-response group, tumor cells took on characteristics of normal endometrial gland cells in the secretory phase. A positive correlation between reduction in the mitotic index and the degree of morphologic alterations during hormone therapy was observed, but the frequency of apoptotic cells did not vary. In both the good-response and poor-response groups, development or enlargement of squamous areas was observed, in comparison with the initial biopsy specimens. CONCLUSIONS: These results suggest that prolonged progesterone administration can suppress cell proliferation in endometrial carcinomas through tumor cell differentiation without altering apoptosis, resulting in a shift in tissue kinetics toward a relative predominance of cell deletion. In addition, increases in the occurrence of squamous areas within tumors do not always appear to be related to treatment efficacy.     

The performance of a microchannel plate at cryogenic temperatures and in high magnetic fields, and the detection efficiency for low energy positive hydrogen ions

We have conducted a systematic study of the performance of a microchannel plate at cryogenic temperatures, and in a magnetic field perpendicular to the plate surface of up to 2.5 T. We observe no change in the characteristic pulse height distribution down to temperatures near 4 K if the count rate is kept sufficiently low. With increasing count rates the onset of saturation effects can be observed to be temperature dependent. For the specific plate used, this occurs around 1 kHz at the lowest temperature. This behavior is in good agreement with calculations based on a widely used model for the gain function of microchannel plates, if the plate resistance is allowed to be temperature dependent. Additionally we have studied the detection efficiency for low energy hydrogen ions of a chevron type microchannel plate under a variety of operating conditions at room temperature, and find the detection efficiency to level off around 60% at energies above 1 keV, if the plate is operated in a saturated gain mode.