-Insensitizing controls for pointwise observations of the heat equation

In this paper, we study the -insensitizing controllability for the functional given by integrating in time the square of the solution of the heat equation in a finite number of points of the domain , i.e., when the observation set is reduced to a finite set of points. We reduce the controllability problem to a unique continuation property for a cascade system of linear heat equations and we obtain a positive result in the case N3.     

Study of dioxolane-dioxepane copolymers through IR and DSC

Summary The composition of the copolymers of 1,3-dioxolane with 1,3-dioxepane was investigated using FT-IR and DSC. The first method produce accurate values for the overall composition, the later allows discriminating between the copolymer and the mixture of homopolymers.     

Mechanical Verification of an Ideal Incremental ABR Conformance Algorithm

The Available Bit Rate protocol (ABR) for ATM networks is well adapted to data traffic by providing minimum rate guarantees and low cell loss to the ABR source end system. An ABR conformance algorithm for controlling the source rates through an interface has been defined by ATM Forum, and a more efficient version of it has been designed by Rabadan and Klay. We present in this work the first complete mechanical verification of the equivalence between these two algorithms. The proof is involved and has been supported by the PVS theorem prover. It has required many lemmas, case analysis, and induction reasoning for the manipulation of unbounded scheduling lists. Some ABR conformance protocols have been verified in previous works. However, these protocols are approximations of the one we consider here. In particular, the algorithms assume a bound on the number of rates to be scheduled.     

A systematic investigation of work function in advanced metal gate–HfO2–SiO2 structures with bevel oxide

This paper presents for the first time the work function extraction for chemical vapor deposition (CVD)-TiN and poly-Si work functions on atomic layer deposition (ALD)-HfO₂ and high temperature SiO₂ (HTO) for a wide range of EOT values. The measurements were performed on bevel oxide structures with various SiO₂ thicknesses from 0 to 12 nm. Our results reveal that the work functions of both TiN and poly-Si gates highly depend on the underlying dielectrics especially in the case of TiN on HTO films. It is found that the leakage current also depends on the dielectric stacks. When TiN is formed on the HTO film, its work function has two distinct values depending on the HTO thickness; this indicates that TiSi bonds strongly affect the work function variation. Both TiN on HTO and poly-Si on HfO₂ show the work function shifts to about 4.3 eV, suggesting a pinning level in both structures.     

Some Aspects of Thermal Stability and the Characteristics of Poly(ethylene terephthalate) (PET) under Stress

In this work we use thermal shrinkage for estimating the internal stresses accumulated in a sample during a technological process. This can be a precious instrument available for every manufacturer interested in the thermal treatment efficiency. Based on the Kelvin‐Voight rheological model, we have established a correlation between the internal stresses appearing during the technological formation processes of yarns and their shrinkage at different temperatures. In this work (PET) fibers were used for study, with different birefringences ranging between 4.2×10^–3–2.2×10^–3. Thermal treatment was performed with warm air at temperatures between 333–453 K. The applied unitary stress changed within the range 5.09×10¹⁰–18.84×10¹³ N·m^–2. From the examination of the curves obtained for free contraction Δε = f (T) for different birefringences Δn for the preoriented PET fibers, contraction increases with increasing temperature up to a maximum situated at ≈ 353 K and then decreases to a constant value. From the examination of the curves, the dimensional change vs. contraction σ = f (Δε), to a thermal treatment under stress for different birefringences Δn, when an external stress σ is applied the thermal stability of the fibers already having on orientation, made evident by the birefringence magnitude, that in the case of a slight orientation, the retraction decreases with increasing temperature. Singular points registered for fibers with Δn = 22×10^–3 for a temperature exceeding 393 K indicate that for the partially orientated fibers the sample is subjected to a stretching process during the thermal stability under stress. We established experimentally a correlation between the strain σ and Δn, Δn = ct. σ/T, i. e., a decrease of the birefringence with increasing temperature.     

Synthesis of Starch Copolymers by Silicon Tetrachloride Plasma‐Induced Graft Polymerization

Corn starch was surface‐functionalized by 13.56 MHz RF SiCl₄‐plasma, in situ reacted with ethylenediamine for stabilization, and subsequently graft‐polymerized using dichlorodimethylsilane as monomer. SiCl₄‐plasma treatment was studied and discharge parameters were optimized. X‐ray photoelectron spectroscopy (XPS/ESCA), Fourier transformed infrared spectroscopy (FTIR), scanning electron spectroscopy (SEM), gas chromatography/mass spectroscopy (GC‐MS), and differential thermal analysis/thermal gravimetry (DTA/TG) proved the presence of a polydimethylsiloxane (PDMS) graft‐copolymer layer on the modified starch‐granule surfaces. These analyses show that the surface morphology of starch granules, the thermal properties, the swelling characteristic, and the hydrophilicity of starch were all changed due to the existence of a protective hydrophobic PDMS layer. It is suggested that the starch graft‐copolymer might find its applications as reinforcing component in silicone‐rubber materials for starch‐based composites.     

Silicon nanowires as negative electrode for lithium-ion microbatteries

The increasingly demand on secondary batteries with higher specific energy densities requires the replacement of the actual electrode materials. With a very high theoretical capacity (4200 mAh g⁻¹) at low voltage, silicon is presented as a very interesting potential candidate as negative electrode for lithium-ion microbatteries. For the first time, the electrochemical lithium alloying/de-alloying process is proven to occur, respectively, at 0.15 V/0.45 V vs. Li⁺/Li with Si nanowires (SiNWs, 200-300 nm in diameter) synthesized by chemical vapour deposition. This new three-dimensional architecture material is well suited to accommodate the expected large volume expansion due to the reversible formation of Li-Si alloys. At present, stable capacity over ten to twenty cycles is demonstrated. The storage capacity is shown to increase with the growth temperature by a factor 3 as the temperature varies from 525 to 575 °C. These results, showing an attractive working potential and large storage capacities, open up a new promising field of research.     

Microstructured Biodegradable Fibers for Advanced Control Delivery

Biodegradable polymers are increasingly employed at the heart of therapeutic devices. Particularly in the form of thin and elongated fibers, they offer an effective strategy for controlled release in a variety of biomedical configurations such as sutures, scaffolds, wound dressings, surgical or imaging probes, and smart textiles. So far however, the fabrication of fiber‐based drug delivery systems has been unable to fulfill significant requirements of medicated fibers such as multifunctionality, adequate mechanical strength, drug loading capability, and complex release profiles of multiple substances. Here, a novel paradigm in the design and fabrication of microstructured biodegradable fibers with tailored mechanical properties and capable of predefined release patterns from multiple reservoirs is proposed. Different biodegradable polymers compatible with the scalable thermal drawing process are identified, and their release properties as thin films of various thicknesses in the fiber form are experimentally investigated and modeled. Multimaterial microstructured fibers with predictable complex release profiles of potentially different substances are then designed and fabricated. Moreover, the tunability of the mechanical properties via tailoring the drawing process parameters is demonstrated, as well as the ability to weave such fibers. This work establishes a novel platform for biodegradable microstructured fibers for applications in implants, sutures, wound dressing, or tissue scaffolds.     

18F-FDG PET/MRI Imaging in a Preclinical Rat Model of Cardiorenal Syndrome—An Exploratory Study

Cardiorenal syndrome (CRS) denotes the bidirectional interaction of chronic kidney disease and heart failure with an adverse prognosis but with a limited understanding of its pathogenesis. This study correlates biochemical blood markers, histopathological and immunohistochemistry features, and 2-deoxy-2-fluoro-D-glucose positron emission tomography (¹⁸F-FDG PET) metabolic data in low-dose doxorubicin-induced heart failure, cardiorenal syndrome, and renocardiac syndrome induced on Wistar male rats. To our knowledge, this is the first study that investigates the underlying mechanisms for CRS progression in rats using ¹⁸F-FDG PET. Clinical, metabolic cage monitoring, biochemistry, histopathology, and immunohistochemistry combined with PET/MRI (magnetic resonance imaging) data acquisition at distinct points in the disease progression were employed for this study in order to elucidate the available evidence of organ crosstalk between the heart and kidneys. In our CRS model, we found that chronic treatment with low-dose doxorubicin followed by acute 5/6 nephrectomy incurred the highest mortality among the study groups, while the model for renocardiac syndrome resulted in moderate-to-high mortality. ¹⁸F-FDG PET imaging evidenced the doxorubicin cardiotoxicity with vascular alterations, normal kidney development damage, and impaired function. Given the fact that standard clinical markers were insensitive to early renal injury, we believe that the decreasing values of the ¹⁸F-FDG PET-derived renal marker across the groups and, compared with their age-matched controls, along with the uniform distribution seen in healthy developing rats, could have a potential diagnostic and prognostic yield in cardiorenal syndrome.