276 research outputs found
Formulation and optimization of the energy-based blended quasicontinuum method
We formulate an energy-based atomistic-to-continuum coupling method based on
blending the quasicontinuum method for the simulation of crystal defects. We
utilize theoretical results from Ortner and Van Koten (manuscript) to derive
optimal choices of approximation parameters (blending function and finite
element grid) for microcrack and di-vacancy test problems and confirm our
analytical predictions in numerical tests
Use of shallow samples to estimate the total carbon storage in pastoral soils
Using data from pastoral soils sampled by horizon at 56 locations across New Zealand, we conducted a meta-analysis. On average, the total depth sampled was 0.93 ± 0.026 m (± SEM), and on a volumetric basis, the total C storage averaged 26.9 ± 1.8, 13.9 ± 0.6 and 9.2 ± 1.4 kg C mâ»ÂČ for allophanic (n=12), non-allophanic (n=40) and pumice soils (n=4), respectively. We estimated the total C storage, and quantified the uncertainty, using the data for samples taken from the uppermost A-horizon whose depth averaged 0.1 ± 0.003 m. For A-horizon samples of the allophanic soils, the mean C content was 108 ± 6 g C kgâ»Âč and the bulk density was 772 ± 29 kg mâ»Âł, for non-allophanic soils they were 51 ± 4 g C kgâ»Âč and 1055 ± 29 kg mâ»Âł, and for pumice soils they were 68 ± 9 g C kgâ»Âč and 715 ± 45 kg mâ»Âł. The C density âa product of the C content and bulk density âof the A-horizon samples was proportional to their air-dried water content, a proxy measure for the mineral surface area. By linear regression with C density of the A-horizon, the total C storage could be estimated with a standard error of 3.1 kg C mâ»ÂČ, 19% of the overall mean
The wool proteome and fibre characteristics of three distinct genetic ovine breeds from Portugal
Wool properties and commodity value vary considerably between breeds. In Portugal, three major ovine groups exist: Churros, Bordaleiros and Merinos. This work studies the effect of the ovine genotype on the wool proteome of such groups. Wool was collected from 15 ewes/breed and genetic groups: Churra da Terra Quente (CTQ) or Churro, Serra da Estrela (SE) or Bordaleiro and Merino Branco (MB) or Merino. Proteins were extracted and subjected to label-free proteomics analysis. A total of 50 keratinous protein groups were identified in all the samples, divided into type I and II keratins and the keratin associated proteins: high-glycine-tyrosine proteins, ultra-high sulphur proteins and high-sulphur proteins. Major differences were found between MB and CTQ with respect to K75 and K38, both medullar proteins and to a lesser extent between SE and CTQ suggesting that these might be good markers for this trait in wool. Partial least squares discriminatory analysis proved MB to be readily distinguishable from the other two breeds. Further differences were noted in keratin associated protein levels between the three breeds, normally an indicator of higher levels of orthocortex and also their relationship to high curvature, high crimp fibres like Merinoinfo:eu-repo/semantics/acceptedVersio
Multiple openings and competitiveness of forward markets: experimental evidence
We test the competition enhancing effect of selling forward in experimental Cournot duopoly and quadropoly with multiple forward markets. We find that having two forward periods yields competitive outcomes and that the results are very close to the predicted theoretical results for both quantity setting duopolies and quadropolies. Our experiments lend strong support to the hypothesis that forward markets are competition enhancing. We then test a new market that allows for endogenously determined indefinitely many forward periods that only close when sellers coordinate on selling a zero amount in a forward market. We find that the outcomes under an endogenous close rule are also very competitive. These results hold for both duopolies and quadropolies
Omental and pleural milky spots: different reactivity patterns in mice infected with Schistosoma mansoni reveals coelomic compartmentalisation
In vertebrate animals, pleural and peritoneal cavities are repositories of milky spots (MS), which constitute an organised coelom-associated lymphomyeloid tissue that is intensively activated by Schistosoma mansoni infection. This study compared the reactive patterns of peritoneal MS to pleural MS and concluded from histological analysis that they represent independent responsive compartments. Whole omentum, lungs and the entire mediastinum of 54 S. mansoni-infected mice were studied morphologically. The omental MS of infected animals were highly activated, modulating from myeloid-lymphocytic (60 days of infection) to lymphomyeloid (90 days of infection) and lymphocytic or lymphoplasmacytic (160 days of infection) types. The non-lymphoid component predominated in the acute phase of infection and was expressed by monocytopoietic, eosinopoietic and neutropoietic foci, with isolated megakaryocytes and small foci of late normoblasts and mast cells. Nevertheless, pleural or thoracic MS of infected mice were monotonous, consisting of small and medium lymphocytes with few mast and plasma cells and no myeloid component. Our data indicate that compartmentalisation of the MS response is dependent on the lymphatic vascularisation of each coelomic cavity, limiting the effects or consequences of any stimulating or aggressive agents, as is the case with S. mansoni infection
Rh-POP Pincer Xantphos Complexes for C-S and C-H Activation. Implications for Carbothiolation Catalysis
The neutral RhÂ(I)âXantphos
complex [RhÂ(Îș<sup>3</sup>-<sub>P,O,P</sub>-Xantphos)ÂCl]<sub><i>n</i></sub>, <b>4</b>, and cationic RhÂ(III) [RhÂ(Îș<sup>3</sup>-<sub>P,O,P</sub>-Xantphos)Â(H)<sub>2</sub>]Â[BAr<sup>F</sup><sub>4</sub>], <b>2a</b>, and [RhÂ(Îș<sup>3</sup>-<sub>P,O,P</sub>-Xantphos-3,5-C<sub>6</sub>H<sub>3</sub>(CF<sub>3</sub>)<sub>2</sub>)Â(H)<sub>2</sub>]Â[BAr<sup>F</sup><sub>4</sub>], <b>2b</b>, are described [Ar<sup>F</sup> = 3,5-(CF<sub>3</sub>)<sub>2</sub>C<sub>6</sub>H<sub>3</sub>; Xantphos
= 4,5-bisÂ(diphenylphosphino)-9,9-dimethylxanthene; Xantphos-3,5-C<sub>6</sub>H<sub>3</sub>(CF<sub>3</sub>)<sub>2</sub> = 9,9-dimethylxanthene-4,5-bisÂ(bisÂ(3,5-bisÂ(trifluoromethyl)Âphenyl)Âphosphine].
A solid-state structure of <b>2b</b> isolated from C<sub>6</sub>H<sub>5</sub>Cl solution shows a Îș<sup>1</sup>-chlorobenzene
adduct, [RhÂ(Îș<sup>3</sup>-<sub>P,O,P</sub>-Xantphos-3,5-C<sub>6</sub>H<sub>3</sub>(CF<sub>3</sub>)<sub>2</sub>)Â(H)<sub>2</sub>(Îș<sup>1</sup>-ClC<sub>6</sub>H<sub>5</sub>)]Â[BAr<sup>F</sup><sub>4</sub>], <b>3</b>. Addition of H<sub>2</sub> to <b>4</b> affords,
crystallographically characterized, [RhÂ(Îș<sup>3</sup>-<sub>P,O,P</sub>-Xantphos)Â(H)<sub>2</sub>Cl], <b>5</b>. Addition of diphenyl
acetylene to <b>2a</b> results in the formation of the CâH
activated metallacyclopentadiene [RhÂ(Îș<sup>3</sup>-<sub>P,O,P</sub>-Xantphos)Â(ClCH<sub>2</sub>Cl)Â(Ï,Ï-(C<sub>6</sub>H<sub>4</sub>)ÂCÂ(H)î»CPh)]Â[BAr<sup>F</sup><sub>4</sub>], <b>7</b>, a rare example of a crystallographically characterized Rhâdichloromethane
complex, alongside the RhÂ(I) complex <i>mer</i>-[RhÂ(Îș<sup>3</sup>-<sub>P,O,P</sub>-Xantphos)Â(η<sup>2</sup>-PhCCPh)]Â[BAr<sup>F</sup><sub>4</sub>], <b>6</b>. Halide abstraction from [RhÂ(Îș<sup>3</sup>-<sub>P,O,P</sub>-Xantphos)ÂCl]<sub><i>n</i></sub> in the presence of diphenylacetylene affords <b>6</b> as the
only product, which in the solid state shows that the alkyne binds
perpendicular to the Îș<sup>3</sup>-POP Xantphos ligand plane.
This complex acts as a latent source of the [RhÂ(Îș<sup>3</sup>-<sub>P,O,P</sub>-Xantphos)]<sup>+</sup> fragment and facilitates
<i>ortho</i>-directed CâS activation in a number
of 2-arylsulfides to give <i>mer</i>-[RhÂ(Îș<sup>3</sup>-<sub>P,O,P</sub>-Xantphos)Â(Ï,Îș<sup>1</sup>-Ar)Â(SMe)]Â[BAr<sup>F</sup><sub>4</sub>] (Ar = C<sub>6</sub>H<sub>4</sub>COMe, <b>8</b>; C<sub>6</sub>H<sub>4</sub>(CO)ÂOMe, <b>9</b>; C<sub>6</sub>H<sub>4</sub>NO<sub>2</sub>, <b>10</b>; C<sub>6</sub>H<sub>4</sub>CNCH<sub>2</sub>CH<sub>2</sub>O, <b>11</b>; C<sub>6</sub>H<sub>4</sub>C<sub>5</sub>H<sub>4</sub>N, <b>12</b>).
Similar CâS bond cleavage is observed with allyl sulfide,
to give <i>fac</i>-[RhÂ(Îș<sup>3</sup>-<sub>P,O,P</sub>-Xantphos)Â(η<sup>3</sup>-C<sub>3</sub>H<sub>5</sub>)Â(SPh)]Â[BAr<sup>F</sup><sub>4</sub>], <b>13</b>. These products of CâS
activation have been crystallographically characterized. For <b>8</b> in situ monitoring of the reaction by NMR spectroscopy reveals
the initial formation of <i>fac</i>-Îș<sup>3</sup>-<b>8</b>, which then proceeds to isomerize to the <i>mer</i>-isomer. With the <i>para</i>-ketone aryl sulfide, 4-SMeC <sub>6</sub>H<sub>4</sub>COMe, CâH activation <i>ortho</i> to the ketone occurs to give <i>mer</i>-[RhÂ(Îș<sup>3</sup>-<sub>P,O,P</sub>-Xantphos)Â(Ï,Îș<sup>1</sup>-4-(COMe)ÂC<sub>6</sub>H<sub>3</sub>SMe)Â(H)]Â[BAr<sup>F</sup><sub>4</sub>], <b>14</b>. The temporal evolution of carbothiolation catalysis using <i>mer</i>-Îș<sup>3</sup>-<b>8</b>, and phenyl acetylene
and 2-(methylthio)Âacetophenone substrates shows initial fast catalysis
and then a considerably slower evolution of the product. We suggest
that the initially formed <i>fac</i>-isomer of the CâS
activation product is considerably more active than the <i>mer</i>-isomer (i.e., <i>mer</i>-<b>8</b>), the latter of
which is formed rapidly by isomerization, and this accounts for the
observed difference in rates. A likely mechanism is proposed based
upon these data
Local therapy of cancer with free IL-2
This is a position paper about the therapeutic effects of locally applied free IL-2 in the treatment of cancer. Local therapy: IL-2 therapy of cancer was originally introduced as a systemic therapy. This therapy led to about 20% objective responses. Systemic therapy however was very toxic due to the vascular leakage syndrome. Nevertheless, this treatment was a break-through in cancer immunotherapy and stimulated some interesting questions: Supposing that the mechanism of IL-2 treatment is both proliferation and tumoricidal activity of the tumor infiltrating cells, then locally applied IL-2 should result in a much higher local IL-2 concentration than systemic IL-2 application. Consequently a greater beneficial effect could be expected after local IL-2 application (peritumoral = juxtatumoral, intratumoral, intra-arterial, intracavitary, or intratracheal = inhalation). Free IL-2: Many groups have tried to prepare a more effective IL-2 formulation than free IL-2. Examples are slow release systems, insertion of the IL-2 gene into a tumor cell causing prolonged IL-2 release. However, logistically free IL-2 is much easier to apply; hence we concentrated in this review and in most of our experiments on the use of free IL-2. Local therapy with free IL-2 may be effective against transplanted tumors in experimental animals, and against various spontaneous carcinomas, sarcomas, and melanoma in veterinary and human cancer patients. It may induce rejection of very large, metastasized tumor loads, for instance advanced clinical tumors. The effects of even a single IL-2 application may be impressive. Not each tumor or tumor type is sensitive to local IL-2 application. For instance transplanted EL4 lymphoma or TLX9 lymphoma were not sensitive in our hands. Also the extent of sensitivity differs: In Bovine Ocular Squamous Cell Carcinoma (BOSCC) often a complete regression is obtained, whereas with the Bovine Vulval Papilloma and Carcinoma Complex (BVPCC) mainly stable disease is attained. Analysis of the results of local IL-2 therapy in 288 cases of cancer in human patients shows that there were 27% Complete Regressions (CR), 23% Partial Regressions (PR), 18% Stable Disease (SD), and 32% Progressive Disease (PD). In all tumors analyzed, local IL-2 therapy was more effective than systemic IL-2 treatment. Intratumoral IL-2 applications are more effective than peritumoral application or application at a distant site. Tumor regression induced by intratumoral IL-2 application may be a fast process (requiring about a week) in the case of a highly vascular tumor since IL-2 induces vascular leakage/edema and consequently massive tumor necrosis. The latter then stimulates an immune response. In less vascular tumors or less vascular tumor sites, regression may require 9â20 months; this regression is mainly caused by a cytotoxic leukocyte reaction. Hence the disadvantageous vascular leakage syndrome complicating systemic treatment is however advantageous in local treatment, since local edema may initiate tumor necrosis. Thus the therapeutic effect of local IL-2 treatment is not primarily based on tumor immunity, but tumor immunity seems to be useful as a secondary component of the IL-2 induced local processes. If local IL-2 is combined with surgery, radiotherapy or local chemotherapy the therapeutic effect is usually greater than with either therapy alone. Hence local free IL-2 application can be recommended as an addition to standard treatment protocols. Local treatment with free IL-2 is straightforward and can readily be applied even during surgical interventions. Local IL-2 treatment is usually without serious side effects and besides minor complaints it is generally well supported. Only small quantities of IL-2 are required. Hence the therapy is relatively cheap. A single IL-2 application of 4.5 million U IL-2 costs about 70 Euros. Thus combined local treatment may offer an alternative in those circumstances when more expensive forms of treatment are not available, for instance in resource poor countries
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