Modeling the flow behavior of a medium carbon microalloyed steel under hot working conditions

The constitutive equations for the flow behavior of a commercial 0.34 pct C-1.5 pct Mn-0.7 pct Si-0.083 pct V-0.018 pct Ti microalloyed steel were determined. For this purpose, uniaxial hot compression tests were carried out over a wide range of strain rates (10⁻⁴ to 10 s⁻¹) and temperatures (1123 to 1423 K). In combination with models developed in the literature, the experimental results permit the flow stress of the present steel to be predicted within ± 5 pct. It is shown that the classical constitutive equations must be modified to take the grain size into account, particularly when the latter is below 30 μm.     

Cost effectiveness of nitrate leaching mitigation measures for grassland livestock systems at locations in England and Wales

As much as 60% of the nitrate in water in England is thought to derive from agriculture. Legislation aims to improve water quality by limiting nitrate concentration in surface and groundwaters to 50 mg l⁻¹. The UK Government responded to the requirements of the EC Nitrate Directive by delineating Nitrate Vulnerable Zones (NVZs) to cover 55% of England in 2002 and increased it to 70% in 2009. In this study we assessed the cost-effectiveness of measures for implementation in livestock systems to mitigate nitrate leaching in the UK. These estimates were prepared for a range of hypothetical farms representative of typical dairy, beef and sheep farms at different locations in England and Wales and for a list of mitigation measures identified to reduce leaching. The NGAUGE and NFixCycle models were used to estimate leaching from these systems. The costs of implementation of the mitigation measures were also assessed in order to evaluate the cost-effectiveness of these measures. In general, the most effective measures to reduce leaching for all systems were the ones that involved a reduction in stocking rates and grazing time, followed by those involving improvements in fertiliser and crop management. Only in the case of the dairy system was effectiveness affected by location of the farm. The costs for implementation in the sheep system were relatively low compared with beef and dairy systems. Implementation of some of the measures with high cost-effectiveness would need to be incentivised financially or with legislation due to the high costs involved.     

Magnetization Reversal in CsNiIICrIII(CN)6 Coordination Nanoparticles: Unravelling Surface Anisotropy and Dipolar Interaction Effects

CsNiCr(CN)₆ coordination nanoparticles with sizes ranging from 6 to 30 nm are highly diluted in an organic polymer matrix. Their static and dynamic magnetic behaviour allows unravelling of surface anisotropy and interparticle dipolar interaction effects. The single magnetic domain critical size is thus evaluated to be around 22 nm with a blocking temperature of 21 K (at ν = 1 Hz) and an effective energy barrier for the reversal of the magnetization of 426 K.     

Supraomohyoid neck dissection in the treatment of T1/T2 squamous cell carcinoma of oral cavity

BACKGROUND: Recent studies in patients with previously untreated T1 and T2 squamous cell carcinoma (SCC) of the tongue and floor of the mouth have shown a relationship between tumor thickness, neck metastasis, and survival. Our study was conducted to determine the indication of elective neck dissection in patients with early oral cavity SCC. PATIENTS AND METHODS: Sixty-seven patients were stratified by stage (T1 and T2 NO), and those in each stage were randomized to receive one of two types of treatment; resection alone (RA) or resection plus elective supraomohyoid neck dissection (RSOND). Fifty-two patients (78%) were men and 15 (22%) were women. The median age was 57 years old (range 34 to 95). RESULTS: Twenty-six (39%) patients had tumor in the floor of the mouth and 41 (61%), in the tongue. Using the criteria of the Union Internationale Contre le Cancer (UICC), 1987, we classified 31 tumors (46%) as T1 lesions and 36 (54%) as T2 lesions. Thirty patients had a tumor thickness < or = 4 mm and 37 had a tumor thickness > 4 mm. Thirty-three (49%) patients were treated with RA, and 34 patients (51%) were treated with RSOND. Seven (21%) patients of the RSOND group had occult cervical metastasis. There were recurrences in 14 (42%) patients of the RA group and 8 (24%) patients of the RSOND group. The disease-free survival rates at 3.5 years for RA and RSOND patients were 49%, and 72%, respectively. The impact of sex, age, site, cancer stage, and tumor thickness was assessed by the Mantel-Haenszel chi-square procedure. Later stage (P = 0.05) and increased tumor thickness (P = 0.005) were significantly associated with treatment failures. CONCLUSION: Neck dissection remains mandatory in the early stage of oral SCC, because of better survival rates compared to RA and the poor salvage rate. In particular, patients with tumor thickness > 4 mm treated with RSOND had significant benefit on disease-free survival.     

Mobile thrombus in the right cardiac cavities in patients with severe pulmonary thromboembolism. Importance of echocardiography

The pulmonary thromboembolism is a frequent and severe disease, usually difficult to recognize, specially in patients with thrombotic material trapped within right heart cavities. We present our experience in three patients with severe pulmonary thromboembolism where echocardiographic study demonstrated the presence of huge mobile thrombus in right heart cavities, which demanded urgent therapy with excellent results. We would like to stress that echocardiographic study in these patients could be elective diagnostic procedure, avoiding the realization of pulmonary arteriography, which could bring risk of possible thrombus mobilization.     

Effect of clustering of precipitates on grain growth

The present work shows that clustering of particles promotes deviation in the classical mathematical expressions describing the grain growth control by second-phase particles. On the basis of experimental results and theoretical laws, a semiempirical expression to predict the limiting grain size is presented. The latter expression takes account of agglomeration phenomena and can be extended to large volume fractions of particles, conditions under which classical theories clearly fail. The equation remains valid as far as the nucleation of precipitates takes place at random. From a practical point of view, it is shown that volume fractions larger than 0.12 cannot significatively control the grain size because of the increased probability for clustering.     

Depressive symptoms in early marriage: Predictions from relationship confidence and negative marital interaction.

The authors proposed a model of depressive symptoms in early marriage in which relationship confidence, defined as perceived couple-level efficacy to manage conflicts and maintain a healthy relationship, mediates the effect of negative marital interactions on depressive symptoms. The model was tested in a sample of 139 couples assessed prior to marriage and 1 year later. As predicted, relationship confidence demonstrated simple negative associations with negative marital interaction and depressive symptoms for all participants. Longitudinal path analyses supported the mediational model for women only. In women but not men, negative marital interaction indirectly had an impact on depressive symptoms through the mediator of relationship confidence. Findings suggest that relationship confidence may be important to understanding links between marital distress and depressive symptoms, especially in women. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Kininogen-derived fluorogenic substrates for investigating the vasoactive properties of rat tissue kallikreins--identification of a T-kinin-releasing rat kallikrein

Peptide substrates with intramolecularly quenched fluorescence that reproduce the rat kininogen sequences at both ends of the bradykinin moiety were synthesized and used to investigate the kinin-releasing properties of five rat tissue kallikreins (rK1, rK2, rK7, rK9, rK10). Substrates derived from rat H- and L-kininogen were cleaved best by rK1, especially that including the N-terminal insertion site of bradykinin, Abz-TSVIRRPQ-EDDnp(Abz = O-aminobenzoyl, EDDnp = ethylenediamine 2,4-dinitrophenyl), which was cleaved at the R-R bond with a k(cat)/Km of 12400 mM(-1) s(-1). Replacement of the P2' residue Pro by Val in Abz-TSVIRRPQ-EDDnp gave a far less specific substrate that was rapidly hydrolysed by all five rat kallikreins and human kallikrein hK1. Peptidyl-N-methyl coumarylamide substrates, which lack prime residues, also had low specificities. The importance of the P2' residue for rK1 specificity was further demonstrated using a human-kininogen-derived substrate that included the N-terminal insertion site of bradykinin (Abz-LMKRP-EDDnp). This was cleaved at the M-K bond by hK1 (kallidin-releasing site), but at the K-R bond (bradykinin-releasing site) by rK1. Competition experiments with Abz-TSVIRRPQ-EDDnp, which is resistant to most kallikreins, and Abz-TSVIRRVQ-EDDnp, a general kallikrein substrate, demonstrated that the former competitively inhibited hydrolysis by rK9 and hK1, with Ki values similar to the Km values for the substrate. Thus Pro in P2' does not prevent the peptide binding to the enzyme active site, but impairs cleavage of the scissile bond. The T-kininogen-derived substrate with the T-kinin C-terminal sequence (Abz-FRLVR-EDDnp) was cleaved by rK10 (k(cat)/Km = 2310 mM(-1) s(-1)) and less rapidly by rK1, rK7 and hK1, at the R-L bond, while that corresponding to the N-terminal (Abz-ALDMMISRP-EDDnp) of T-kinin was resistant to all five kallikreins used, suggesting that none has T-kininogenase activity. But this substrate was hydrolysed by a semipurified sample of submandibular gland extract. Another kallikrein, identified as kallikrein rK3, was isolated from this fraction and shown to hydrolyze Abz-ALDMMISRP-EDDnp; rK3 also specifically released T-kinin from purified T1/T2-kininogen after HPLC fractionation. Injection of purified rK3 and of Abz-ALDMMISRP-EDDnp-cleaving fractions into the circulation of anesthesized rats caused transient falls in blood pressure, as did purified rK1 but none of the other purified rat or human kallikreins. This effect occurred via activation of the kinin system since it was blocked by Hoe140, a kinin receptor antagonist.