Lightweight metallic matrix composites. Development of new composites material reinforced with carbon structures

Carbon nano/micro-structures used as fillers in metallic lightweight alloys matrix composites are receiving considerable attention in scientific research and industrial applications. Aluminum and magnesium are the most studied light metals used as matrices in metal composites materials principally for their low density (respectively 2.7 g/cm3 and 1.7 g/cm3) and low melting temperature (around 660 °C for both metals). A good interaction between matrix and fillers is the first step to obtain an increase in bulk properties; furthermore, the manufacturing procedure of the composite is fundamental in terms of quality of fillers dispersion. In this work the influence of surface modifications for three classes of carbon fillers for aluminum and magnesium alloy (AZ63) as matrices is studied. In particular, the selected fillers are short carbon micro fibres (SCMFs), carbon woven fabrics (CWF) and unidirectional yarn carbon fibres (UYFs). The surface modification was carried out by a direct coating of pure nickel on fibres. The electroless pure nickel plating was chosen as coating technique and the use of hydrazine as reducing agent has prevented the co-deposition of other elements (such as P or B). SEM and EDS analyses were performed to study the effect of surface modifications. The mechanical properties of manufactured composites were evaluated by four point flexural tests according to ASTM C1161 (room temperature). Results confirm improved interactions between matrix and fillers, and the specific interaction was studied for any chosen reinforcement

Clinical management of endoscopically resected pT1 colorectal cancer

Background Implementation of colorectal cancer (CRC) screening programs increases endoscopic resection of polyps with early invasive CRC (pT1). Risk of lymph node metastasis often leads to additional surgery, but despite guidelines, correct management remains unclear. Our aim that are diagnosed and treated endoscopically and this number is expected to increase [1,2].Methods We retrospectively reviewed patients undergoing endoscopic resection of pT1 CRC from 2006 to 2016. Clinical, endoscopic, surgical treatment, and follow-up data were collected and analyzed. Lesions were categorized according to endoscopic/histological risk-factors into low and high risk groups. Comorbidities were classified according to the Charlson comorbidity index (CCI). Surgical referral for each group was computed, and dissociation from current European CRC screening guidelines recorded. Multivariate analysis for factors affecting the post-endoscopic surgery referral was performed.Results Seventy-two patients with endoscopically resected pT1-CRC were included. Overall, 20 (27.7%) and 52 (72.3%) were classified as low and high risk, respectively. In the low risk group, 11 (55%) were referred to surgery, representing over-treatment compared with current guidelines. In the high risk group, nonsurgical endoscopic surveillance was performed in 20 (38.5%) cases, representing potential under-treatment. After a median follow-up of 30 (6-130) months, no patients developed tumor recurrence. At multivariate analysis, age (OR 1.21, 95 %CI 1.02 -1.42; P = 0.02) and CCI (OR 1.67, 95 %CI 1.12 -3.14; P= 0.04) were independent predictors for subsequent surgery.Conclusions A substantial rate of inappropriate post-endoscopic treatment of pT1-CRC was observed when compared with current guidelines. This was apparently related to an overestimation of patient-related factors rather than endoscopically or histologically related factors

Atrophy, oxidative switching and ultrastructural defects in skeletal muscle of the ataxia telangiectasia mouse model

Ataxia telangiectasia is a rare, multi system disease caused by ATM kinase deficiency. Atm-knockout mice recapitulate premature aging, immunodeficiency, cancer predisposition, growth retardation and motor defects, but not cerebellar neurodegeneration and ataxia. We explored whether Atm loss is responsible for skeletal muscle defects by investigating myofiber morphology, oxidative/glycolytic activity, myocyte ultrastructural architecture and neuromuscular junctions. Atm-knockout mice showed reduced muscle and fiber size. Atrophy, protein synthesis impairment and a switch from glycolytic to oxidative fibers were detected, along with an increase of in expression of slow and fast myosin types (Myh7, and Myh2 and Myh4, respectively) in tibialis anterior and solei muscles isolated from Atm-knockout mice. Transmission electron microscopy of tibialis anterior revealed misalignments of Z-lines and sarcomeres and mitochondria abnormalities that were associated with an increase in reactive oxygen species. Moreover, neuromuscular junctions appeared larger and more complex than those in Atm wild-type mice, but with preserved presynaptic terminals. In conclusion, we report for the first time that Atm-knockout mice have clear morphological skeletal muscle defects that will be relevant for the investigation of the oxidative stress response, motor alteration and the interplay with peripheral nervous system in ataxia telangiectasia

Enhancing methane production from food waste fermentate using biochar. The added value of electrochemical testing in pre-selecting the most effective type of biochar

Background: Recent studies have suggested that addition of electrically conductive biochar particles is an effective strategy to improve the methanogenic conversion of waste organic substrates, by promoting syntrophic associations between acetogenic and methanogenic organisms based on interspecies electron transfer processes. However, the underlying fundamentals of the process are still largely speculative and, therefore, a priori identification, screening, and even design of suitable biochar materials for a given biotechnological process are not yet possible. Results: Here, three charcoal-like products (i.e., biochars) obtained from the pyrolysis of different lignocellulosic materials, (i.e., wheat bran pellets, coppiced woodlands, and orchard pruning) were tested for their capacity to enhance methane production from a food waste fermentate. In all biochar-supplemented (25 g/L) batch experiments, the complete methanogenic conversion of fermentate volatile fatty acids proceeded at a rate that was up to 5 times higher than that observed in the unamended (or sand-supplemented) controls. Fluorescent in situ hybridization analysis coupled with confocal laser scanning microscopy revealed an intimate association between archaea and bacteria around the biochar particles and provided a clear indication that biochar also shaped the composition of the microbial consortium. Based on the application of a suite of physico-chemical and electrochemical characterization techniques, we demonstrated that the positive effect of biochar is directly related to the electron-donating capacity (EDC) of the material, but is independent of its bulk electrical conductivity and specific surface area. The latter properties were all previously hypothesized to play a major role in the biochar-mediated interspecies electron transfer process in methanogenic consortia. Conclusions: Collectively, these results of this study suggest that for biochar addition in anaerobic digester operation, the screening and identification of the most suitable biochar material should be based on EDC determination, via simple electrochemical tests. © 2017 The Author(s)

Postharvest characteristics of cut flowers of selected members of the family Myrtaceae : a thesis presented in fulfilment of the requirements for the degree of Master of Philosophy at Massey University, New Zealand

Stages of floral development were described for Eucalyptus ficifolia and Metrosideros collina 'Tahiti' flowers (Myrtaceae) attached and detached from plants. Vase solution treatments were applied to promote bud opening of cut flowers and to prevent postharvest stamen wilting and abscission in both species. Water uptake and mass of harvested flowers in both species declined rapidly when the pedicels were placed in water (control). Some flower buds did not open after harvest. The decline in water uptake and flower mass was greatly reduced by a vase solution treatment containing 2% sucrose, and 200 ppm hydroxyquinoline citrate (HQC) adjusted to pH 4 using citrate buffer. Vase solutions containing higher sucrose concentrations (more than 6%) and of greater acidity (pH<4) were not beneficial for vase life of both species. Cut flowers of both species held in the standard solution (2% sucrose, 200 ppm HQC adjusted to pH 4 using citrate buffer) were treated with ethephon (0-10,000 ppm) following pre-treatment with silver thiosulphate (STS) (0-2.0 mM). Ethephon treatments significantly induced stamen wilting, but had no effect on stamen or petal abscission in both species. Pre-treatment with 2 mM STS had no effect on the rate of stamen wilting, but significantly reduced stamen or petal abscission in both species. Cut flowers of M. collina 'Tahiti' held in the standard solution were treated with ethylene (0-5 ppm). Exogenous ethylene significantly promoted abscission of stamens and petals in M. collina 'Tahiti'. Treatment with 0.5 and 5 ppm ethylene also induced flower abscission. Ethylene emanation from untreated cut flowers from plants grown in two environments (greenhouse and outside) was also measured. Untreated cut flowers harvested from plants grown outside produced more endogenous ethylene than those from plants grown in the greenhouse. The abscission of M. collina 'Tahiti' probably results from a relatively high sensitivity to ethylene

Computing the Shapley value in allocation problems: approximations and bounds, with an application to the Italian VQR research assessment program

In allocation problems, a given set of goods are assigned to agents in such a way that the social welfare is maximised, that is, the largest possible global worth is achieved. When goods are indivisible, it is possible to use money compensation to perform a fair allocation taking into account the actual contribution of all agents to the social welfare. Coalitional games provide a formal mathematical framework to model such problems, in particular the Shapley value is a solution concept widely used for assigning worths to agents in a fair way. Unfortunately, computing this value is a #P-hard problem, so that applying this good theoretical notion is often quite difficult in real-world problems. We describe useful properties that allow us to greatly simplify the instances of allocation problems, without affecting the Shapley value of any player. Moreover, we propose algorithms for computing lower bounds and upper bounds of the Shapley value, which in some cases provide the exact result and that can be combined with approximation algorithms. The proposed techniques have been implemented and tested on a real-world application of allocation problems, namely, the Italian research assessment program known as VQR (Verifica della Qualità della Ricerca, or Research Quality Assessment)1. For the large university considered in the experiments, the problem involves thousands of agents and goods (here, researchers and their research products). The algorithms described in the paper are able to compute the Shapley value for most of those agents, and to get a good approximation of the Shapley value for all of the