Fabrication and mechanical response of commingled GF/PET composites

The mechanical properties and the response to mechanical load of continuous glass fiber reinforced polyethylene terephthalate (GF/PET) laminates have been characterized. The laminates were manufactured by compression molding stacks of novel woven and warp knitted fabrics produced from commingled yarns. The laminate quality was examined by means of optical and scanning electron microscopy. Few voids were found and the laminate quality was good. Resin pockets occurred in the woven laminates, originating from the architecture of the woven fabric. The strength of the fiber/matrix interface was poor. Some problems were encountered while manufacturing the laminates. These led to fiber misalignment and consequently resulted in tensile mechanical properties that were slightly lower than expected. Flexural failures all initiated as a result of compression, and it is possible that the compression strength of the matrix material, rather than its tensile strength, might limit the ultimate mechanical performance of the composites. Flexural failures for both materials were very gradual. The warp knitted laminates were stronger and stiffer than the woven laminates. The impact behavior was also investigated; the woven laminates exhibited superior damage tolerance compared with the warp knitted laminates.     

2,2‐Dinitro‐1,3‐Bis‐Nitrooxy‐Propane (NPN): A New Energetic Plasticizer

A new energetic plasticizer, 2,2‐dinitro‐1,3‐bis‐nitrooxy‐propane (NPN), has been characterized. Its high oxygen balance, +12.5%, and low glass transition temperature, −81.5 °C (midpoint), makes it very attractive as an energetic plasticizer in solid propellants. The ability of NPN to lower the glass transition temperature and viscosity of uncured PolyNIMMO has been studied and compared to other energetic plasticizers, such as BDNPA/F and butyl‐NENA. NPN has a similar plasticizing effect as butyl‐NENA, both on depressing the glass transition temperature and lowering the viscosity. To increase the poor thermal stability of NPN, several conventional nitrocellulose/nitroglycerine stabilizers were evaluated. Further work is however needed to find a more effective stabilizer.     

Transformation of the TiNi Alloy Microstructure and the Mechanical Properties Caused by Repeated B2-B19′ Martensitic Transformations

The influences of thermal cycling treatment in the temperature range of B2-B19 martensitic transformations (-150 to 150 °C) on the TiNi alloy structure and properties were studied. Different states named the initial coarse-grained (CG) state, the ultrafine-grained (UFG) state after ECAP (with a grain size of 200 nm), the state after ECAP and cold upsetting by 30% were considered. The results show that the microhardness and the strength increase in all the three states. According to the XRD analysis, a more significant increment in the dislocation density, resulting from thermal cycling, is observed in the UFG alloy than in the CG alloy.     

Investigating the feasibility of DLC-coated twist drills in deep-hole drilling

The ideal coating for twist drills used to drill deep holes should have both a high hardness and a smooth surface. The latter property is considered to ease chip evacuation through the drill’s chip flutes and, therefore, reduces the risk of chip clogging and possible premature drill fractures. For this reason, diamond-like carbon (DLC) appears to be a well-suited type of coating. This paper presents the results of cutting tests using DLC-coated HSS and cobalt-HSS twist drills when drilling deep holes of diameter 1.5 mm into plain carbon steel. Their capability to extract swarf from the borehole as well as their tool lives were investigated and compared to uncoated and TiN- and MoS₂-coated drills. Although the DLC-coated drills showed a very good swarf disposal capability, they did not exhibit a longer tool life when compared to off-the-shelf drills.     

Expansion of a physical function item bank and development of an abbreviated form for clinical research

We expanded an existing 33-item physical function (PF) item bank with a sufficient number of items to enable computerized adaptive testing (CAT). Ten items were written to expand the bank and the new item pool was administered to 295 people with cancer. For this analysis of the new pool, seven poorly performing items were identified for further examination. This resulted in a bank with items that define an essentially unidimensional PF construct, cover a wide range of that construct, reliably measure the PF of persons with cancer, and distinguish differences in self-reported functional performance levels. We also developed a 5-item (static) assessment form ("BriefPF") that can be used in clinical research to express scores on the same metric as the overall bank. The BriefPF was compared to the PF-10 from the Medical Outcomes Study SF-36. Both short forms significantly differentiated persons across functional performance levels. While the entire bank was more precise across the PF continuum than either short form, there were differences in the area of the continuum in which each short form was more precise: the BriefPF was more precise than the PF-10 at the lower functional levels and the PF-10 was more precise than the BriefPF at the higher levels. Future research on this bank will include the development of a CAT version, the PF-CAT.     

An evaluation of DGT performance using a dynamic numerical model

A numerical model of the transport and dynamics of metal complexes in the resin and gel layers of a DGT (diffusive gradients in thin films) device was developed and used to investigate how the chelating resin and metal-ligand complexes in solution affect metal uptake. Decreasing the stability constant or concentration of the binding resin increases the competition for free metal ions by ligands in solution, lowering the rate of mass uptake. Such effects would be rarely observed for moderately or strongly binding resins (K> 10(12)), including Chelex, which out-compete labile ligands in solution. With weakly binding resins, strongly bound solution complexes can diffuse into the resin layer before a measurable amount of dissociation occurs, such that concentrations of bound metal at the rear and front surfaces of the resin layer are equal. With more strongly binding resins, metal mainly binds to the front surface of the resin. Only complexes with the largest binding constants penetrate the gel layer containing Chelex, buttheir lack of lability means thatthe DGT sensitivity to the complex is, in any case, very low. The slow diffusion of complexes, such as those of fulvic acids, which increases the time required to establish steady state, compromises the use of the simple DGT equation. Errors are negligible for 24 h deployments, when diffusive layer thicknesses are less than 1 mm, but 3 day deployments are required to ensure accuracy with 2.4 mm thick layers. The extent to which the commonly used equation, that accounts for the concentration and diffusion of metal-complex species, overestimates DGT uptake if the rate of dissociation is slow, was estimated.     

Carbon dioxide adsorption on mesoporous silica surfaces containing amine-like motifs

The postcombustion separation of CO₂ from a flue gas mixture is a unit operation in carbon capture. Today, CO₂ is normally separated with alkanolamines in aqueous solutions. These absorption processes are energy intensive and costly. Increased environmental considerations and the significant footprints of many energy sources warrant the development of new gas separation techniques for the competitive implementation of carbon capture and storage technologies. Improved adsorbent-mediated separation processes are candidates for such new low-energy low-cost processes. In this study, porous silica-based adsorbents with amine-like motifs were synthesized. The temperature- and pressure-dependent adsorption of CO₂ and CO₂/H₂O mixtures were determined and compared for these materials. The experimental uptake capacities of the materials modified with primary propyl amine moieties were significantly higher than those of materials modified with bis-ethanol amine or amidine. The propyl-amine-modified samples also showed good selectivity for CO₂ over nitrogen gas.     

Screening for organic phosphorus compounds in aquatic sediments by liquid chromatography coupled to ICP-AES and ESI-MS/MS

The structures of organic phosphorous (P) compounds in aquatic sediments are to a large extent unknown although these compounds are considered to play an important role in regulating lake trophic status. To enhance identification of these compounds, a liquid chromatography (LC) method for their separation was developed. The stationary phase was porous graphitic carbon (PGC), and the mobile phases used in the gradient elution were compatible with both inductive coupled plasma atomic emission spectroscopy (ICP-AES) and electrospray ionization tandem mass spectrometry (ESI-MS/MS). With LC-ICP-AES, eight different P containing peaks could be observed in the P chromatogram indicating that at least eight different P compounds were separated. With the setup of an information dependent acquisition (IDA) with ESI-MS/MS, the mass over charge ( m/ z) of compounds containing a phosphate group (H 2PO 3 (-), m/ z 97) could be measured and further fragmentation experiments gave additional information on the structure of almost 40 separated P compounds, several were verified to be nucleotides. ICP-AES was very suitable in the development of the LC method and allowed screening and quantification of P compounds. The presented LC-ESI-MS/MS technique was able to identify several sediment organic P compounds.     

Probe diffusion in κ-carrageenan gels determined by fluorescence recovery after photobleaching

The effects of free volume and heterogeneity on probe diffusion in κ-carrageenan gels were determined by fluorescence recovery after photobleaching (FRAP) and rheology. By changing the ionic conditions, biopolymer concentration and end temperature, different microstructures and aggregation kinetics in the κ-carrageenan gels were evaluated. The results of the FRAP measurements were compared to transmission electron microscopy (TEM) and nuclear magnetic resonance diffusometry (NMRd) data from previous studies. The results showed that the free diffusion rates of the probe (FITC dextran) in water were influenced by both temperature and ionic conditions. The free diffusion values were used for normalization of the diffusion rates in the κ-carrageenan gel measurements. The compatibility between FITC dextran with different molecular weights (10 and 500 kDa) and κ-carrageenan was evaluated. The results showed that the larger FITC dextran probe phase separates; therefore only the 10 kDa FITC dextran probe was used in the FRAP experiments. FRAP measurements and NMRd probe diffusion in combination with TEM in κ-carrageenan revealed that the void space, degree of aggregation and heterogeneity influence the probe diffusion rate. The κ-carrageenan gelation was analyzed at different end temperatures using rheology and FRAP. The FITC dextran probe diffusion was not influenced by κ-carrageenan aggregation, regardless of rheological gelation kinetics and storage modulus near the gel point. This indicates that the average void space between the gel strands is larger than the size of the probe. Good correlation between the microstructure and the probe diffusion rate in κ-carrageenan gel with different ionic conditions and constant biopolymer concentration were obtained with TEM and FRAP.