Micro/nanometric investigations of the effects of laser ablation in the generation of micro-tools from solid CVD diamond structures

Using pulsed laser ablation, a novel method has been successfully developed for the generation of micro-features in diamond thus enabling the production of precision abrasive like micro-cutting elements into solid diamond micro-grinding tools. This paper examines the effects of the laser ablation on the generation of abrasive micro-features in diamond by using electron energy loss spectroscopy (EELS) and transmission electron microscopy (TEM). Site specific specimen preparation by a focus ion beam (FIB) material removal process has been made possible by the application of platinum and tungsten protective layers, providing the necessary specimen surface stability during the ion beam milling and lift-out operations. The prepared thin section orientated orthogonally to the cutting edge of a laser generated abrasive feature, has allowed the identification of the graphite and diamond allotropes across the ablated interface using EELS. A sequence of TEM images has revealed the extent of surface graphitisation and the high integrity of the diamond substructure. TEM examinations at nanometric resolutions have allowed the visualisation of the diamond and graphite allotropes at molecular level while depicting the abrupt graphite to diamond transition resulting in a highly defined boundary, thereby endorsing the capabilities of the laser ablation process to generate cutting edges with minimal structural damage.     

Prospects for the incorporation of cobalt into α-Fe2O3 nanorods during hydrothermal synthesis

A feasibility study on the incorporation of cobalt into α-Fe₂O₃ nanorods (NRs) during hydrothermal synthesis (HS) is presented as a function of FeCl₃ and CoCl₂ concentration, phosphate surfactant concentration and pH value, with samples assessed using X-ray diffractometry, transmission electron microscopy, selected area electron diffraction and energy dispersive X-ray analysis. No evidence was found for the incorporation of cobalt into α-Fe₂O₃ NRs at low pH, whilst synthesis at intermediate and high pH values favoured the formation of CoFe₂O₄ NPs. The critical role of pH value over the precipitation, size and phase purity of the nanostructured reaction products is emphasised. At pH ~2, large, well crystalline α-Fe₂O₃ nanoparticles (NPs) and NRs were grown from FeCl₃ solution in the absence and presence of phosphate, respectively, whilst no evidence was found for Co precipitation or incorporation in α-Fe₂O₃ following HS in the presence of CoCl₂. At pH ~8, smaller α-Fe₂O₃ NPs, as well as Co₃O₄ and CoFe₂O₄ NPs were synthesised from FeCl₃, CoCl₂, or a mixture thereof. HS at pH ~12 produced a mixture of larger CoFe₂O₄ NPs and α-Fe₂O₃ NPs depending on the Fe:Co molar ratio. The formation of intermediate metastable (oxy)hydroxide phases is considered pH dependent, providing for a variety of different reaction pathways. Further, inclusion of preformed Co₃O₄ and CoFe₂O₄ NPs to the FeCl₃ solution at pH ~2 in the presence of phosphate surfactant resulted in the synthesis of α-Fe₂O₃ NRs with residual Co₃O₄ and CoFe₂O₄ NPs attached to their surfaces. The CoFe₂O₄ NPs encouraged local dissolution leading to the formation of α-Fe₂O₃ NR surface corrugations.     

Freeze–thaw damage and chemical change of a portland cement concrete in the presence of diluted deicers

The present study experimentally investigates the effect of different diluted deicers on concrete deterioration. Laboratory simulations of environmental freeze/thaw cycling were first conducted on Portland cement concrete specimens in the presence of various deicers (NaCl, K-formate, NaCl-based deicer, K-acetate-based deicer, Na-acetate/Na-formate blend deicer, CMA deicer, or MgCl₂ liquid deicer); and SEM/EDX measurements were then conducted for the concrete samples. Under the experimental conditions in this study, the CMA solid deicer and the MgCl₂ liquid deicer were benign to the concrete durability, whereas K-formate and the Na-acetate/Na-formate blend deicer showed moderate amount of weight loss and noticeable deterioration of the concrete. NaCl, the NaCl-based deicer, and the K-acetate-based deicer were the most deleterious to the concrete. In addition to exacerbating physical distresses, each investigated chemical or diluted deicer chemically reacted with some of the cement hydrates and formed new products in the pores and cracks. Such physiochemical changes of the cement paste induced by the deicers pose various levels of risks for the concrete durability.     

Microcrystalline/micromorph silicon thin-film solar cells prepared by VHF-GD technique

Hydrogenated microcrystalline silicon prepared at low temperatures by the glow discharge technique is examined here with respect to its role as a new thin-film photovoltaic absorber material. XRD and TEM characterisations reveal that microcrystalline silicon is a semiconductor with a very complex morphology. Microcrystalline p–i–n cells with open-circuit voltages of up to 560–580 mV could be prepared. “Micromorph” tandem solar cells show under outdoor conditions higher short-circuit currents due to the enhanced blue spectra of real sun light and therefore higher efficiencies than under AM1.5 solar simulator conditions. Furthermore, a weak air mass dependence of the short-circuit current density could be observed for such micromorph tandem solar cells. By applying the monolithic series connection based on laser patterning a first micromorph mini-module (total area of 23.6 cm²) with 9% cell conversion efficiency could be fabricated.     

A phase I study of recombinant human soluble interleukin-1 receptor (rhu IL-1R) in patients with relapsed and refractory acute myeloid leukemia

PURPOSE: The recombinant human interleukin-1 receptor (rhu IL-1R) is a soluble truncated form of the type 1 full-length membrane-bound receptor that binds IL-1 with identical affinity to that of the membrane form. As such, it may have clinical potential by sequestering IL-1, thereby preventing it from binding to its membrane-bound receptor and eliciting a biological effect. As IL-1 has been shown to regulate leukemic cell proliferation in an autocrine fashion, a phase I trial of rhu IL-1R was conducted in patients with relapsed and refractory acute myeloid leukemia (AML). METHODS: The study group comprised 11 patients who were sequentially treated on one of three dose levels, receiving a single intravenous (i.v.) bolus dose on day 1 followed by 13 days of daily subcutaneous (s.c.) injections with the option of an additional 14 days of treatment if a response of stable disease or better was achieved. Dose level 1 i.v. bolus 500 microg/m2, s.c. dose 250 microg/m2 per day (five patients); dose level 2 i.v. bolus 1000 microg/m2, s.c. dose 500 microg/m2 per day (three patients); dose level 3 i.v. bolus 2000 microg/m2, s.c. dose 1000 microg/m2 per day (three patients). Owing to limited drug availability, the study was designed to only examine these three dose levels. RESULTS: rhu IL-IR was well tolerated. There was no grade 3 or 4 non-hematological toxicity related to the study drug and the maximum tolerated dose was not reached. No IL-1R-blocking antibodies developed during the course of the study. Serum levels of IL-1beta, IL-6 and TNF were undetectable before, during and after rhu IL-IR administration. The terminal half-life after i.v. dosing was at least 7-12 h, and after s.c. dosing 2-4 days. Serum levels of rhu IL-1R up to 360- and 25-fold those of pretreatment levels were achieved after i.v. and s.c. dosing respectively. No patient had a complete, partial or minor response to treatment; four had stable disease and seven had progressive disease. CONCLUSIONS: rhu IL-1R therapy was safe but did not have any apparent antileukemic effect at the doses administered.     

Lessons learned from three interorganizational health care information systems

The airline, financial, retail, consumer goods and cotton industries are not alone in their increased use of interorganizational information systems (IOSs). Health care organizations are investing and participating in a growing number of IOSs, such as community health information networks (CHINs) and integrated delivery systems (IDS). This paper examines the experiences of three CHIN systems located in the US — Midwest. Multiple data sources, including executive interviews, memoranda, internal documentation and system demonstrations, provided data for this research. The history of each case provides a better understanding of systems implementation and the underlying determinants that emerged as having significant impact. Not only do these findings provide guidelines and learning tools for practitioners, but they also hold implications to the field and its current position on bipolar streams in the literature. Lastly, our findings suggest that large health care infrastructures will continue to be confronted by the presence of the World Wide Web and electronic commerce.     

Effect of pair-breaking on the superconducting fluctuation contribution to the NMR relaxation rate

We investigate the effect of pair-breaking on the contribution of s-wave order parameter fluctuations to the NMR relaxation rate for clean 2D superconductors. For Gaussian fluctuations we evaluate the Maki-Thomson diagram taking into account pairing breaking in both the fluctuation propagator and the Green's functions. The fluctuation peak in 1/T ₁ near T_c is strongly reduced by pair-breaking as is the case for the Hebel-Slichter peak.