A Convenient One-Step Synthesis of 5-(α-alkanonyl) and 5-(α-Cyclanonyl)-4-Pentanolides

The thermolysis of t-butyl perpent-4-enoate in ketones leads to the formation of 5-(α-alkanonyl) and 5-(α-cyclanonyl)-4-pentanolides with fairly good yields.     

A Fully Nonlinear Nonhomogeneous Neumann Problem

Let Ω be an open bounded set in ℝ^N, N≥3, with connected Lipschitz boundary ∂Ω and let a(x,ξ) be an operator of Leray–Lions type (a(⋅,∇u) is of the same type as the operator |∇u|^p−2∇u, 1<p<N). If τ is the trace operator on ∂Ω, [φ] the jump across ∂Ω of a function φ defined on both sides of ∂Ω, the normal derivative ∂/∂ν_a related to the operator a is defined in some sense as 〈a(⋅,∇u),ν〉, the inner product in ℝ^N, of the trace of a(⋅,∇u) on ∂Ω with the outward normal vector field ν on ∂Ω. If β and γ are two nondecreasing continuous real functions everywhere defined in ℝ, with β(0)=γ(0)=0, f∈L¹(ℝ^N), g∈L¹(∂Ω), we prove the existence and the uniqueness of an entropy solution u for the following problem,

Novel Helmholtz-based photoacoustic sensor for trace gas detection at ppm level using GaInAsSb/GaAlAsSb DFB lasers

A new and compact photoacoustic sensor for trace gas detection in the 2-2.5 microm atmospheric window is reported. Both the development of antimonide-based DFB lasers with singlemode emission in this spectral range and a novel design of photoacoustic cell adapted to the characteristics of these lasers are discussed. The laser fabrication was made in two steps. The structure was firstly grown by molecular beam epitaxy then a metallic DFB grating was processed. The photoacoustic cell is based on a Helmholtz resonator that was designed in order to fully benefit from the highly divergent emission of the antimonide laser. An optimized modulation scheme based on wavelength modulation of the laser source combined with second harmonic detection has been implemented for efficient suppression of wall noise. Using a 2211 nm laser, sub-ppm detection limit has been demonstrated for ammonia.     

NMR Spectroscopic Assignment of Backbone and Side‐Chain Protons in Fully Protonated Proteins: Microcrystals,Sedimented Assemblies,and Amyloid Fibrils

We demonstrate sensitive detection of alpha protons of fully protonated proteins by solid‐state NMR spectroscopy with 100–111 kHz magic‐angle spinning (MAS). The excellent resolution in the Cα‐Hα plane is demonstrated for 5 proteins, including microcrystals, a sedimented complex, a capsid and amyloid fibrils. A set of 3D spectra based on a Cα–Hα detection block was developed and applied for the sequence‐specific backbone and aliphatic side‐chain resonance assignment using only 500 μg of sample. These developments accelerate structural studies of biomolecular assemblies available in submilligram quantities without the need of protein deuteration.     

Validation of Monte Carlo simulation of 6 MV photon beam produced by Varian Clinac 2100 linear accelerator using BEAMnrc code and DOSXYZnrc code

The Monte Carlo model for the photon-beam output from the Varian Clinac 2100 linear accelerator was validated to compare the calculated to measured PDD and beam dose profiles The Monte Carlo calculation method is considered to be the most accurate method for dose calculation in radiotherapy. The objective of this study is to build a Monte Carlo geometry of Varian Clinac 2100 linear accelerator as realistically as possible. The Monte Carlo codes used in this work were the BEAMnrc code to simulate the photons beam and the DOSXYZnrc code to examinate the absorbed dose in the water phantom. We have calculated percentage depth dose (PDD) and beam profiles of the 6 MV photon beam for the 6 × 6 cm², 10 × 10 cm² and 15 × 15 cm² field sizes. We have used the gamma index technique for the quantitative evaluation to compare the measured and calculated distributions. Good agreement was found between calculated PDD and beam profile compared to measured data. The comparison was evaluated using the gamma index method and the criterions were 3% for dose difference and 3 mm for distance to agreement. The gamma index acceptance rate was more than 97% of both distribution comparisons PDDs and dose profiles and our results were more developed and accurate. The Varian Clinac 2100 linear accelerator was accurately modeled using Monte Carlo codes: BEAMnrc and DOSXYZnrc codes package.     

Photon beam softening coefficients evaluation for a 6 MeV photon beam for an aluminum slab: Monte Carlo study using BEAMnrc Code,DOSXYZnrc Code,and BEAMDP code

Determination and understanding the photon beam attenuation by the photon beam modifier and the radiation beam softening for clinical use is more important part of material study for the beam modifier enhancements and the linac improvements. A Monte Carlo model was used to simulate 6 MeV photon beams from a Varian Clinac 2100 accelerator with the flattening filter and the later was replaced by the aluminum slab with variable thickness. The Monte Carlo geometry was validated by a gamma index acceptance rate of 99% in PDD and 98% in dose profiles, the gamma criteria was 3% for dose difference and 3 mm for distance to agreement. The purpose was to investigate aluminum material attenuation and beam softening coefficients as a function of the inserted aluminum slab thickness and of off-axis distance. The attenuation and beam softening coefficients were not identical for the same off-axis distance and they varied as a function of aluminum slab thickness. The results of our study were shown that the beam softening coefficients were varied with thickness beam modifier material used for beam softening and the off-axis distance inside the irradiation field. Thereafter, the softening coefficient a ₁ have a maximum of 2.5 × 10^–1 cm^–1 for the aluminum slab thickness of 1 mm, 1.4 × 10^–1 cm^–1 for the aluminum slab thickness of 1.5 mm and 4.47 × 10^–2 cm^–1 for the aluminum slab thickness of 2 mm. The maximum of the second softening coefficient a ₂ was 1.02 × 10^–2 cm^–2 for the aluminum slab thickness of 1 mm, was 1.92 × 10^–2 cm^–2 for the aluminum slab thickness of 1.5 mm and was 1.93 × 10^–2 cm^–2 for the aluminum slab thickness of 2 mm. Our study can be a basic investigation of photon beam softening material that will be used in the future linac configuration and also in the photon beam modifiers.     

Intramolecular homolytic displacements 7 — Free radical additions to unsaturated peroxy compounds : Synthesis of oxygenated heterocycles

Free radical additions of hydrogen donor solvents to tert-butyl perpent-4-enoate have given 4-substituted γ-butyrolactones, with yields of 50 % or greater. Such reactions applied to allyl-tert-butyl peroxide have produced 2,3-epoxypropanation of these solvents. Similar addition-elimination processes occurred with tert-butyl 4-methyl-perpent-4-enoate, tert-butyl 2,2-dimethyl-perpent-4-enoate and tert-butyl-methallyl peroxide, but they failed with tert-butyl 5-methyl-perhex-4-enoate and tert-butyl-3-methyl-but-2-enyl peroxide.     

Inverse thermal analysis of the drying zone of the evaporator of an axially grooved heat pipe

An inverse approach is performed to characterize the thermal behaviour of an axially grooved heat pipe, in steady state, for various operating conditions. For this purpose, an experimental set up, as well as a network conduction model, are developed to simulate the heat transfer in the wall at the evaporator section. The minimization of an objective function, taking into account the discrepancy between measured temperatures and computed ones, allows then the estimation of a heat transfer coefficient as well as the drying out front positions for all the axial grooves. Hence, at the burnout point, the significant temperature increase in the evaporator extremity is considered to be a direct consequence of the restriction of the evaporative zone. Therefore, the distribution of liquid phase in the capillary structure of the heat pipe can be obtained through the analysis of the measured temperature gradient in the evaporator section where the dry out front was expected to occur. Furthermore, the dry out front expansion can be observed when the input heat load is increased or when the adiabatic temperature is decreased. Introducing an adverse tilt angle also shows the effect of the puddle.     

Anticancer effect of three pyrazole derivatives

The evaluation of the cytotoxic properties in vitro of three synthetic tripods containing pyrazole: N,N-bis[(3,5-dimethylpyrazol-1-yl)methyl]aniline (1); N,N-tetrakis[(3,5-dimethylpyrazol-1-yl)methyl]-para-phenylenediamine (2); and N,N-tetrakis-[(1,5-dimethylpyrazol-3-yl)methyl]-para-phenylenediamine (3), was examined for their cytotoxic activity on two tumor cell lines: P815 (murin mastocytoma) and Hep (human laryngeal carcinome). While the compound 2 shows a small cytotoxic activity, compounds 1 and 3 are more cytotoxic against both cell lines. However, this cytotoxicity is more pronounced against Hep cell line (IC50: 3.25 microg mL(-1) for compound 1 and 6.92 microg mL(-1) for compound 3) than P815 cell line (IC50: 17.82 microg mL(-1) for compound 1 and 37.21 microg mL(-1) for compound 3). Statistical analysis shows that the compound 1 is two- to threefold more cytotoxic than compound 3 (P < 0.05). Interestingly, the cytotoxicity induced by compound 1 against Hep cell line is more important than that induced by adriamycin used as a positive control.