SMA applications in an innovative multishot deployment mechanism

An innovative Deployment and Retraction hinge Mechanism (DARM) in the frame of a technological program is examined. The mechanism includes two restraint/release devices, which enable it to be stable in its stowed or deployed position while sustaining all associated loads, and to carry its payload by remote command. The main characteristics of the DARM are as follows: deployment and retraction movements are spring actuated; the available amount of functional sequences is almost unlimited; and no use of electrical motors is made. These features were accomplished by: the application of a special kinematic scheme to the mechanical connection between the spring motor and the swivel head arm; and the use of shape memory alloys (SMA) actuators for both release and spring recharge functions. DARM is thus a mechanism which can find many applications in the general space scenario of in-orbit maintenance and servicing. In such a frame, the DARM typical concept, which has a design close to very simple one-shot deployment mechanisms, has a good chance to replace existing analog machines. Potential items that could be moved by DARM are: booms for satellite instruments; antenna reflector tips; entire antenna reflectors; and solar panels

A multiscale approach for the nonlinear mechanical response of 3-phases fiber reinforced graphene nanoplatelets polymer composite materials

This work presents an analytical approach for solving the nonlinear mechanical response of hybrid glass fibers reinforced graphene polymer composite materials. Two-scale homogenization technique derives the effective properties of the composite. At the first scale, the properties of a 2-phases graphene/polymer composite are obtained by accounting for the J2 plasticity coupled with the “Lemaitre–Chaboche” ductile damage model. An interfacial imperfection between the fillers and the matrix is considered through the linear spring model (LSM). At the second scale, the modeling of the 3-phases glass fibers/graphene/polymer composite combines the 2-phases composite as a matrix phase in which are embedded the glass fibers. For both scales, a modified Mori–Tanaka scheme derives the effective properties. Numerical results, obtained for a thermoplastic PA6 matrix, are compared with the multistep method of Digimat software. Finally, a tension–torsion test shows that the imperfection at the fibers/polymer interface is the driven parameter to weaken mechanical responses in the shear direction

Food assistance to tuberculosis patients: lessons from Afghanistan.

Poverty, food insecurity and poor nutrition in the population are important contributors to the burden of tuberculosis (TB). For poor and food-insecure individuals, accessing and successfully completing anti-tuberculosis treatment over an extended period of time is challenging. Food and nutritional support as an incentive and enabler is employed by national TB control programmes (NTPs) worldwide as a means to encourage treatment initiation and adherence and to improve the nutritional status of patients with TB. It also offers a safety net for food-insecure households affected by TB to mitigate the financial consequences of the disease. This paper reports on the primary lessons from the review of the World Food Programme's (WFP's) Food Assistance Programme for TB patients in Afghanistan. It aims to inform the design, implementation and scale-up of TB programmes in settings where food insecurity and malnutrition are prevalent. It also documents qualitative findings that suggest that patients, their families and providers viewed food support as an important asset and an essential element of the national TB control strategy. While the impact on treatment success or case detection could not be quantified, it is likely that the WFP intervention had a positive impact on the patients and their households, therefore contributing to the success of the DOTS-based NTP

The Economic Burden of Tuberculosis and the Mitigation Effect of Social Protection: A Population-Based Study in Ghana

Background: Tuberculosis (TB), a major global public health concern, is known as a disease of the poor. However, evidence on the economic burden of TB is limited, and so is the literature on the impact of poverty alleviation strategies, such as social protection (SP), on financial protection for TB patients. This PhD aimed to contribute to the body of knowledge on the costs and affordability of TB care, and on the potential mitigation effect of SP on TB patient costs. Conceptual analyses and empirical data I collected as part of a nationally representative TB patient cost survey in Ghana were used to address these objectives: 1) Provide evidence on the level, and composition, of costs incurred by TB-affected households and affordability of TB care; 2) Investigate determinants of costs, and the impact of National Health Insurance (NHIS) on costs; 3) Explore the potential impact of costs on TB treatment outcomes. Results: This thesis showed that TB patients in Ghana face financial catastrophe and impoverishment due to the cost of TB care. The poorest and those with drug-resistant TB have increased odds of experiencing catastrophic costs. NHIS in its current form is not effective in defraying costs, and its expansion will not be effective to relieve the financial burden for TB-affected households. Further, this thesis did not find an effect of costs on treatment outcomes as, like most TB patient cost surveys, our study was not powered to detect such an association. Conclusion: SP schemes require enhancement if they are to protect TB patients from financial catastrophe. Evidence generated from this thesis provides original insights into affordability of TB care, lending weight to policy recommendations on financial protection for TB patients. This PhD also shows both the potential and limitations of TB patient cost surveys to assess the impact of social protection strategies on costs, and of TB-related costs on treatment outcomes, thus calling for further methodological developments, and outlining a clear map for future research

Thermal, viscoelastic and mechanical behavior of polypropylene with synthetic boehmite alumina nanoparticles

Effects of nanofiller concentration and surface treatments on the morphology, thermal, viscoelastic and mechanical behaviors of polypropylene copolymer (PP)/boehmite alumina (BA) nanocomposites were investigated. Both untreated and treated BA particles with octylsilane (OS) and with sulphonic acid compound (OS2) were added up to 10 wt% to produce nanocomposites by melt mixing followed by film blow molding and hot pressing. Dispersion of BA was studied by scanning electron microscopy. Differential scanning calorimetry and wide-angle X-ray scattering were adopted to detect changes in the crystalline structure of PP. Thermooxidative degradation of the nanocomposites was assessed by thermogravimetrical analysis. Dynamic mechanical analysis served for studying the viscoelastic, whereas quasi-static tensile, creep and Elmendorf tear tests were used to detect changes in the mechanical performance. BA nanoparticles were finely dispersed in PP up to 10 wt%, even when they were not surface modified. The resistance to thermal degradation was markedly improved by BA nanomodification. Changes observed in the mechanical properties were attributed to BA dispersion, filler/matrix interactions and related effects because the crystalline characteristics of the PP matrix practically did not change with BA modification

Pancreatic cancer-associated diabetes mellitus: an open field for proteomic applications.

Background: Diabetes mellitus is associated with pancreatic cancer in more than 80% of the cases. Clinical, epidemiological, and experimental data indicate that pancreatic cancer causes diabetes mellitus by releasing soluble mediators which interfere with both beta-cell function and liver and muscle glucose metabolism. Methods: We analysed, by matrix-assisted laser desorption ionization time of flight (MALDI-TOF), a series of pancreatic cancer cell lines conditioned media, pancreatic cancer patients' peripheral and portal sera, comparing them with controls and chronic pancreatitis patients' sera. Results: MALDI-TOF analysis of pancreatic cancer cells conditioned media and patients' sera indicated a low molecular weight peptide to be the putative pancreatic cancer-associated diabetogenic factor. The sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis of tumor samples from diabetic and non-diabetic patients revealed the presence of a 1500 Da peptide only in diabetic patients. The amino acid sequence of this peptide corresponded to the N-terminal of an S-100 calcium binding protein, which was therefore suggested to be the pancreatic cancer-associated diabetogenic factor. Conclusions: We identified a tumor-derived peptide of 14 amino acids sharing a 100% homology with an S-100 calcium binding protein, which is probably the pancreatic cancer-associated diabetogenic facto

Pancreatic cancer-derived S-100A8 N-terminal peptide: a diabetes cause?

BACKGROUND: Our aim was to identify the pancreatic cancer diabetogenic peptide. METHODS: Pancreatic tumor samples from patients with (n=15) or without (n=7) diabetes were compared with 6 non-neoplastic pancreas samples using SDS-PAGE. RESULTS: A band measuring approximately 1500 Da was detected in tumors from diabetics, but not in neoplastic samples from non-diabetics or samples from non-neoplastic subjects. Sequence analysis revealed a 14 amino acid peptide (1589.88 Da), corresponding to the N-terminal of the S100A8. At 50 nmol/L and 2 mmol/L, this peptide significantly reduced glucose consumption and lactate production by cultured C(2)C(12) myoblasts. The 14 amino acid peptide caused a lack of myotubular differentiation, the presence of polynucleated cells and caspase-3 activation. CONCLUSIONS: The 14 amino acid peptide from S100A8 impairs the catabolism of glucose by myoblasts in vitro and may cause hyperglycemia in vivo. Its identification in biological fluids might be helpful in diagnosing pancreatic cancer in patients with recent onset diabetes mellitus