Infected pancreatic necrosis: outcomes and clinical predictors of mortality. A post hoc analysis of the MANCTRA-1 international study

: The identification of high-risk patients in the early stages of infected pancreatic necrosis (IPN) is critical, because it could help the clinicians to adopt more effective management strategies. We conducted a post hoc analysis of the MANCTRA-1 international study to assess the association between clinical risk factors and mortality among adult patients with IPN. Univariable and multivariable logistic regression models were used to identify prognostic factors of mortality. We identified 247 consecutive patients with IPN hospitalised between January 2019 and December 2020. History of uncontrolled arterial hypertension (p = 0.032; 95% CI 1.135-15.882; aOR 4.245), qSOFA (p = 0.005; 95% CI 1.359-5.879; aOR 2.828), renal failure (p = 0.022; 95% CI 1.138-5.442; aOR 2.489), and haemodynamic failure (p = 0.018; 95% CI 1.184-5.978; aOR 2.661), were identified as independent predictors of mortality in IPN patients. Cholangitis (p = 0.003; 95% CI 1.598-9.930; aOR 3.983), abdominal compartment syndrome (p = 0.032; 95% CI 1.090-6.967; aOR 2.735), and gastrointestinal/intra-abdominal bleeding (p = 0.009; 95% CI 1.286-5.712; aOR 2.710) were independently associated with the risk of mortality. Upfront open surgical necrosectomy was strongly associated with the risk of mortality (p < 0.001; 95% CI 1.912-7.442; aOR 3.772), whereas endoscopic drainage of pancreatic necrosis (p = 0.018; 95% CI 0.138-0.834; aOR 0.339) and enteral nutrition (p = 0.003; 95% CI 0.143-0.716; aOR 0.320) were found as protective factors. Organ failure, acute cholangitis, and upfront open surgical necrosectomy were the most significant predictors of mortality. Our study confirmed that, even in a subgroup of particularly ill patients such as those with IPN, upfront open surgery should be avoided as much as possible. Study protocol registered in ClinicalTrials.Gov (I.D. Number NCT04747990)

Lattice curvature generation in graded InxGa1-xAs/GaAs buffer layers

Position dependent lattice tilts in InGaAs/GaAs (001) compositionally graded buffer layers are investigated. The lateral dependence of the tilt defines a concave buffer layer curvature of up to 3 deg cm21. The buffer layer curvature is associated with a distribution of the misfit dislocation Burgers vectors that varies nearly linearly across the sample. The origin of this peculiar distribution is discussed and is explained in terms of a Burgers-vector selection rule, which governs the cross slip of gliding threading dislocations and that has been experimentally observed by Capano in Phys. Rev. B 45, 11 768 (1992). A quantitative model of lattice curvature formation is presented that satisfactorily accounts for the main features of the observed buffer layer curvature. © 2000 The American Physical Societ

Lattice distortion in InxGa1-xAs/InP epitaxial films: a second- and third-shell XAFS study

We investigate the lattice distortion of pseudomorphic epitaxial InxGa(1-x)As/InP thin films by polarization dependent x-ray absorption fine-structure spectroscopy; five samples with In concentration in the range 0.25\u20130.75 and strain ranging from tensile to compressive have been investigated. We find that the measured second and third-shell distances exhibit a clear dependence on the angle between the photon beam and the sample normal, in agreement with the expected tetragonal distortion of the unit cell. A method is proposed to extract from the polarization-dependent measurements the values of the strain-induced split of second- and third-shell interatomic distances. The values obtained by this method are in excellent agreement with the predictions of a model that calculates the variations of interatomic distances due to strain by applying the macroscopic strain tensor at local scale and linearly summing the known alloying effect. This model was applied successfully to the first shell distances in previous papers; the application to the second and third shells is a further confirmation of the validity of the model in the InxGa(1-x)As structure

Modeling of self-interstitial diffusion in implanted molecular beam epitaxy silicon

In this work a rate equations model describing the interstitials (I) diffusion in a trap containing medium is presented. The model takes into account the interstitial injection by implantation and annealing and the surface evaporation. We found an analytical approximated solution of the model which allows clarifying the interplay between the parameters involved and a simple comparison with experimental data obtained by the analysis of boron delta doping arrays broadening. The calculations allow to demonstrate that the I injected into the bulk and toward the surface at the end of the I clusters dissolution does not depend on the detailed time evolution of the I clusters, but only on the total amount of I produced by the implantation. The fitting of the experimental data allows to easily quantifying important physical parameters such as the I evaporation rate at the surface and the density of intrinsic interstitial traps. Applications of the model are shown in the case of MBE materials intentionally doped with substitutional C. The model successfully predicts the TED reduction by MBE intrinsic I-traps and allows to estimate the average composition of Interstitial-Carbon clusters

Strain effect on interatomic distances in InGaAs/InP epitaxial layers

Using X-ray absorption fine structure spectroscopy (XAFS) with synchrotron radiation, we have performed an in-depth study on the strain-induced deformations in the first three coordination shells of (InGa)As epilayers deposited on InP(0 0 1). In order to obtain information on the second and third coordination shells, we have exploited the directional sensitivity of XAFS. All the experimental results can be reproduced by applying the macroscopic strain matrix to the local scale, independent of the chemical nature of the interatomic correlations

Behaviour of metastable Si/sub 1 y/C/sub y/ epilayers under 2 MeV alpha particles irradiation

In this work we present some recent results concerning the alpha - particles irradiation of Si(1-y)Cy alloy epitaxially grown on silicon. The study of the damaging process is interesting because of the extensive use of backscattering technique as a tool of characterization of this kind of materials and because of the possibility of adding information about the transformations that this metastable material undergoes. We point out that the irradiation damaging process causes a change in the material structure different from that due to the thermal treatments. The irradiation damage occurs at a rate much higher than in Si, however it involves only a silicon atoms fraction that appears to be proportional to the substitutional carbon content

Behaviour of metastable si1-yCy epilayers under 2 MeV alpha particles irradiation

Miner. Metals &Mater Soc. Warrendale US

Dissolution kinetics of boron-interstitial clusters in silicon

In this work, we have investigated the stoichiometry of boron-interstitial clusters (BICs) produced in a molecular-beam-epitaxy-grown B box by Si implantation and annealing, and their dissolution during further prolonged annealing cycles. Low-concentration B delta doping was used to quantitatively monitor the interstitial (I) flux. A stoichiometric ratio of about 1.2 between I and B was found for the BICs formed at 815 °C. The BIC dissolution kinetics was investigated by analyzing the concentration profiles at different times and temperatures in the range 815–950 °C with a simulation code able to deconvolve the processes of B diffusion and B release from clusters. We found that the main mechanism for cluster dissolution is the release of interstitial boron atoms, with a thermal activation energy of 3.2 +- 0.4 eV. These data are discussed and compared with existing literature data. © 2003 American Institute of Physics