Innovative Al Alloys for High Performance Automotive Pistons: Enhancement of Specific Strength at High Temperature and Resistance to Knock Damage

The increasingly strict regulations on greenhouse gas emissions make the fuel economy a pressing factor for automotive manufacturers. Lightweighting and engine downsizing are two strategies pursued to achieve the target. In this context, materials play a key role since these limit the engine efficiency and components weight, due to their acceptable thermo-mechanical loads. Piston is one of the most stressed engine components and it is traditionally made of Al alloys, whose weakness is to maintain adequate mechanical properties at high temperature due to overaging and softening. The enhancement in strength-to-weight ratio at high temperature of Al alloys had been investigated through two approaches: increase of strength at high temperature or reduction of the alloy density. Several conventional and high performance Al-Si and Al-Cu alloys have been characterized from a microstructural and mechanical point of view, investigating the effects of chemical composition, addition of transition elements and heat treatment optimization, in the specific temperature range for pistons operations. Among the Al-Cu alloys, the research outlines the potentialities of two innovative Al-Cu-Li(-Ag) alloys, typically adopted for structural aerospace components. Moreover, due to the increased probability of abnormal combustions in high performance spark-ignition engines, the second part of the dissertation deals with the study of knocking damages on Al pistons. Thanks to the cooperation with Ferrari S.p.A. and Fluid Machinery Research Group - Unibo, several bench tests have been carried out under controlled knocking conditions. Knocking damage mechanisms were investigated through failure analyses techniques, starting from visual analysis up to detailed SEM investigations. These activities allowed to relate piston knocking damage to engine parameters, with the final aim to develop an on-board knocking controller able to increase engine efficiency, without compromising engine functionality. Finally, attempts have been made to quantify the knock-induced damages, to provide a numerical relation with engine working conditions.

TAZ role in lung cancer: resistance to BET inhibitors and functional interaction with lncRNA

Despite extensive research and introduction of innovative therapy, lung cancer prognosis remains poor, with a five years survival of only 17%. The success of pharmacological treatment is often impaired by drug resistance. Thus, the characterization of response mechanisms to anti-cancer compounds and of the molecular mechanisms supporting lung cancer aggressiveness are crucial for patient’s management. In the first part of this thesis, we characterized the molecular mechanism behind resistance of lung cancer cells to the Inhibitors of the Bromodomain and Extraterminal domain containing Proteins (BETi). Through a CRISPR/Cas9 screening we identified three Hippo Pathway members, LATS2, TAOK1 and NF2 as genes implicated in susceptibility to BETi. These genes confer sensitivity to BETi inhibiting TAZ activity. Conversely, TAZ overexpression increases resistance to BETi. We also displayed that BETi downregulate both YAP, TAZ and TEADs expression in several cancer cell lines, implying a novel BETi-dependent cytotoxic mechanism. In the second part of this work, we attempted to characterize the crosstalk between the TAZ gene and its cognate antisense long-non coding RNA (lncRNA) TAZ-AS202 in lung tumorigenesis. As for TAZ downregulation, TAZ-AS202 silencing impairs NSCLC cells proliferation, migration and invasion, suggesting a pro-tumorigenic function for this lncRNA during lung tumorigenesis. TAZ-AS202 regulates TAZ target genes without altering TAZ expression or localization. This finding implies an uncovered functional cooperation between TAZ and TAZ-AS202. Moreover, we found that the EPH-ephrin signaling receptor EPHB2 is a downstream effector affected by both TAZ and TAZ-AS202 silencing. EPHB2 downregulation significantly attenuates cells proliferation, migration and invasion, suggesting that, at least in part, TAZ-AS202 and TAZ pro-oncogenic activity depends on EPH-ephrin signaling final deregulation. Finally, we started to dissect the mechanism underlying the TAZ-AS202 regulatory activity on EPHB2 in lung cancer, which may involve the existence of an intermediate transcription factor and is the object of our ongoing research.

Investigating the mechanisms of Moraxella catarrhalis resistance to oxidative stress

Moraxella catarrhalis (Mcat) represents a human pathogen implicated in debilitating diseases, such as Chronic Obstructive Pulmonary Disease (COPD). One of the hallmarks of COPD is the excessive neutrophil oxidative stress mediated by reactive oxygen species (ROS). Mcat shows a higher innate level of resistance to exogenous oxidative stress compared to the co-infecting human airways pathogens such as non-typeable Haemophilus influenzae (NTHi) but the underlying mechanisms are currently not well defined. In this thesis, we demonstrated that, differently from NTHi, Mcat was able to directly interfere with ROS production and ROS-related responses such as neutrophil extracellular traps (NET) and autophagy in differentiated neutrophilic-like dHL-60 cells and primary cells. The underlying mechanisms were shown to be phagocytosis/opsonins-independent but contact-dependent, due to the engagement of the immunosuppressive receptors. Indeed, we identified that through OmpCD porin, Mcat was able to engage Siglec inhibitory receptors suppressing ROS generation by the host cells. Furthermore, Mcat provided a safer niche for the co-infecting NTHi bacterium which was otherwise susceptible to the host antimicrobial arsenal. Subsequently, to deeply characterize the Mcat global transcriptional response to oxidative stress, an RNA-Seq experiment was performed on exponentially growing bacteria exposed to sublethal amounts of H2O2 or CuSO4, stimuli that the pathogens experienced once they are phagocytosed. We unraveled a previously unidentified common transcriptional program following H2O2 and CuSO4 exposure, demonstrating a similar defense mechanism to the stress conditions encountered in neutrophils. We ascertained new crucial factors for this pathogen response and established a novel in vivo Mcat infection model, using the invertebrate Galleria mellonella. Actually, we observed that deletion mutants of genes implicated in oxidative stress resistance exhibited reduced virulence. In conclusion, this work represents an important step in the understanding of Mcat innate resistance mechanisms to oxidative stress and further elucidate the virulence mechanisms during infection.

Understanding molecular mechanisms of resistance to immune checkpoint inhibitors in advanced non-small cell lung cancer (NSCLC)

Immune checkpoint inhibitors (ICI) that target PD-1/PD-L1 have recently emerged as an integral component of front-line treatment in metastatic NSCLC patients. The PD-1 inhibitor pembrolizumab is approved as monotherapy for advanced NSCLC with a PD-L1 tumor proportion score (TPS) of ≥1% and in combination with platinum doublet chemotherapy regardless of PD-L1 expression level. However, responses to either regimen occur in only a minority of cases, and PD-L1 TPS is limited as a biomarker in predicting whether a cancer will respond to PD-1 inhibition alone or would be more likely to benefit from PD-1 inhibition plus chemotherapy. Additional biomarkers of immunotherapy efficacy, such as tumor mutational burden (TMB), have not been incorporated into routine clinical practice for treatment selection. The identification of patients who have the greatest likelihood of responding to immunotherapies is critical for guiding treatment decisions. IN addition, early indicators of response could theoretically prevent patients from staying on an ineffective therapy where they might experience complications due to disease progression or develop toxicities from unnecessary exposure to an inactive agent. The aim of this research project is to investigate the clinicopathologic and molecular determinant of response/resistance to the currently available immune checkpoint inhibitors, in order to identify therapeutic vulnerabilities that can be exploited to improve the clinical outcomes of patients with advanced NSCLC.

Esterase profile in the postembryonic development of Rhipicephalusmicroplus

The objective of this work was to analyze the pattern of esterase activity in the development stages of Rhipicephalus microplus by nondenaturing polyacrylamide gel electrophoresis using specific staining for esterase. The electrophoretical results revealed the presence of nine regions displaying esterase activity, stained with both alpha-naphthyl acetate and beta-naphthyl acetate, and classified as alpha-beta-esterase. Stage-specific esterases were found, with the first nymphal and larval stages showing the greatest esterase activity throughout the development. An esterase called EST-4 was detected only in males and was considered sex-specific. There are differences in the esterase profile among the different postembryonic development stages of R. microplus.

Esterase profile in a pyrethroid-resistant Brazilian strain of the cattle tick Boophilus microplus (Acari, Ixodidae)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Esterase profile in the postembryonic development of Rhipicephalusmicroplus

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Resistance of Santa Ines and crossbred ewes to naturally acquired gastrointestinal nematode infections

This trial was carried out in Piracicaba, Sao Paulo State. Brazil. to comparatively evaluate the degree of resistance to naturally acquired gastrointestinal nematode infections in sheep of the following genetic groups purebred Santa Ines (SI), SI crossbred with Dorper (DO x SI), lie de France (IF x SI), Suffolk (SU x SI), and Texel (TE < SI) Fifteen ewes from each group were raised indoors until 12 months of age. At this age, they were moved to pasture that was naturally contaminated by nematode infective larvae and were evaluated from December to May. 2007. Rainfall ranged from 267 mm in January to 37 mm in April Maximum and minimum mean temperatures ranged from 32 5 degrees C to 19 0 degrees C in March and from 25.9 degrees C to 12.8 degrees C in May. There was an increase in the mean number of eggs per gram of feces (EPG) after animals were placed on pasture with significant difference between the SI (80 EPG) and IF x SI (347 EPG) groups in January: and the DO x SI (386 EPG) and TE x SI (258 EPG) groups in May. The highest mean fecal egg count (FEC), 2073 EPG, was recorded for the TE x SI group in February. All groups showed a progressive reduction in body weight throughout the experiment of 12.0% (TE x SI) to 15.9% (SU x SI). In general. the animals with the highest FEC presented the lowest packed cell volumes (PCV): the highest correlation coefficient between FEC x PCV occurred in the SU x SI sheep in January (r = -0.70; P < 0.01). Similarly, there was an inverse relationship between FEC and blood eosinophil Values, with the highest correlation coefficient in the TE x SI sheep in February (r = -0.64; P < 0.05). Immunoglobulin G (IgG) levels against Haemonchus contortus antigens increased in all groups as a result of the exposure to parasites and remained relatively constant until the end of the study, with the exceptions of SU x SI and TE x SI, which showed a rise in IgG levels during the last sampling that coincided with a reduction in mean FEC. In conclusion. crossbreeding Santa Ines sheep with any of the breeds evaluated can result in a production increase and the maintenance of a satisfactory degree of infection resistance, especially against H. contortus and Trichostrongylus colubriformis. the major nematodes detected in this flock. (c) 2009 Elsevier B.V. All rights reserved.

A Survey for Diclofop-Methyl Resistance in Italian Ryegrass from Tennessee and How To Manage Resistance in Wheat

Italian ryegrass resistance to diclofop has been documented in several countries, including the United States. The purpose of this research was to screen selected putative resistant populations of Italian ryegrass for resistance to the acetyl-CoA carboxylase (ACCase)-inhibiting herbicides diclofop and pinoxaden and the acetolactate synthase (ALS)-inhibiting herbicides imazamox, pyroxsulam, and mesosulfuron in the greenhouse and to use field experiments to develop herbicide programs for Italian ryegrass control. Resistance to diclofop was confirmed in eight populations from Tennessee. These eight populations did not show cross-resistance to pinoxaden. One additional population (R1) from Union County, North Carolina, was found to be resistant to both diclofop and pinoxaden. The level of resistance to pinoxaden of the R1 population was 15 times that of the susceptible population. No resistance was confirmed to any of the ALS-inhibiting herbicides examined in this research. Field experiments demonstrated PRE Italian ryegrass control with chlorsulfuron (71 to 94%) and flufenacet + metribuzin (84 to 96%). Italian ryegrass control with pendimethalin applied PRE or delayed preemergence (DPRE) was variable (0 to 85%). POST control of Italian ryegrass was acceptable with pinoxaden, mesosulfuron, flufenacet + metribuzin, and chlorsulfuron + flucarbazone (> 80%). Application timing and herbicide treatment had no effect on wheat yield, except for diclofop and pendimethalin treatments, in which uncontrolled Italian ryegrass reduced wheat yield.

Yield response of rice (Oryza sativa L.) genotypes to different types of drought under rainfed lowlands - Part 3. Plant factors contributing to drought resistance

A series of experiments were conducted in drought-prone northeast Thailand to examine the magnitude of yield responses of diverse genotypes to drought stress environments and to identify traits that may confer drought resistance to rainfed lowland rice. One hundred and twenty eight genotypes were grown under non-stress and four different types of drought stress conditions. Under severe drought conditions, the maintenance of PWP of genotypes played a significant role in determining final grain yield. Because of their smaller plant size (lower total dry matter at anthesis) genotypes that extracted less soil water during the early stages of the drought period, tended to maintain higher PWP and had a higher fertile panicle percentage, filled grain percentage and final grain yield than other genotypes. PWP was correlated with delay in flowering (r = -0.387) indicating that the latter could be used as a measure of water potential under stress. Genotypes with well-developed root systems extracted water too rapidly and experienced severe water stress at flowering. RPR which showed smaller coefficient of variation was more useful than root mass density in identifying genotypes with large root system. Under less severe and prolonged drought conditions, genotypes that could achieve higher plant dry matter at anthesis were desirable. They had less delay in flowering, higher grain yield and higher drought response index, indicating the importance of ability to grow during the prolonged stress period. Other shoot characters (osmotic potential, leaf temperature, leaf rolling, leaf death) had little effect on grain yield under different drought conditions. This was associated with a lack of genetic variation and difficulty in estimating trait values precisely. Under mild stress conditions (yield loss less than 50%), there was no significant relationship between the measured drought characters and grain yield. Under these mild drought conditions, yield is determined more by yield potential and phenotype than by drought resistant mechanisms per se. (C) 2002 Elsevier Science B.V. All rights reserved.

A foliar rating system for comparing the resistance of banana cultivars grown as tissue-cultured plantlets in the laboratory to Fusarium wilt

A foliar rating system was developed to assess the progress of Fusarium wilt ( Panama disease) caused by Fusarium oxysporum f. sp. cubense in seven banana cultivars differing in their resistance to race 1 of the pathogen. Plantlets were transplanted into unamended soil naturally infested with the pathogen, soil amended with urea and soil amended with aged chicken manure. A corm invasion score was also developed to assess the accuracy of the foliar symptom score as an indicator of cultivar resistance. On the basis of foliar symptom scores alone, the response of five of the seven cultivars in the chicken manure treatment corresponded to their known field response. However, the response of the other two cultivars, both susceptible to the pathogen in the field, fell into two categories. One had a high foliar symptom score and a correspondingly high corm invasion score, whereas the other had a low foliar symptom score and a high corm invasion score. Breeders need to be aware of the two categories of susceptible response, if inferior breeding material is to be rejected early on in a breeding program.

Genetic divergence in cocoa progenies for backcrossing program to witches' broom disease resistance

Backcrossing has been little used in cacao breeding, particularly due to the long time required to transfer genes and recover the genetic background of the recurrent parent. The objective of this study was to select individuals, resulting from the backcross CEPEC-42 x SIC-19, genetically related to the recurrent parent SIC-19 by using RAPD molecular markers, among those with resistance to witches' broom. Of the 31 plants that clustered with SIC-19, 18 from the replanted material remained free of the disease in the field, with good vegetative aspect and, therefore can be used for backcross to reach the desired objective.

Resistance of Streptococcus pneumoniae to antimicrobials in São Paulo, Brazil: clinical features and serotypes

To study resistance to antimicrobials, serotypes and clinical features of S. pneumoniae in S. Paulo, Brazil, 50 patients with a positive culture were evaluated: 7 were considered carriers and 43 had pneumococcal infections. Pneumonia and meningitis were the most commom infections. Mortality was 34% and underlying diseases were present in 70%. Relative resistance to penicillin occurred in 24% and complete resistance was not detected. Resistance to tetracycline was 32% and to sulfamethoxazole/trimethoprim 32%; one strain had intermediate susceptibility to erythromycin; no resistance was present for chloramphenicol, rifampin or vancomycin. Resistance to at least one of the drugs tested occurred in 62%. Results by the E-test for penicillin were similar to those by the agar dilution method. There were 24 different serotypes and 74% of the strains belonged to the 23-valent vaccine including all the penicillin-resistant strains. In this study S. pneumoniae caused severe infections and presented a high resistance rate to commonly used antimicrobials. Routine surveillance of resistance and the use of vaccination, as well as the restriction of inappropriate use of antimicrobials, are recommended in São Paulo, Brazil.

Studies on resistance and response to vancomycin in Enterococcus faecalis: a last resort antibiotic

Dissertation presented to obtain a Ph.D. degree in Biochemistry by Instituto de Tecnologia Química e Biológica Universidade Nova de Lisboa.

Influenza A(H1N1)pdm09 Resistance and Cross-Decreased Susceptibility to Oseltamivir and Zanamivir Antiviral Drugs

Neuraminidase inhibitors (NAIs) oseltamivir and zanamivir are currently the only effective antiviral drugs available worldwide for the management of influenza. The potential development of resistance is continually threatening their use, rationalizing and highlighting the need for a close and sustained evaluation of virus susceptibility. This study aimed to analyze and characterize the phenotypic and genotypic NAIs susceptibility profiles of A(H1N1)pdm09 viruses circulating in Portugal from 2009 to 2010/2011. A total of 144 cases of A(H1N1)pdm09 virus infection from community and hospitalized patients were studied, including three suspected cases of clinical resistance to oseltamivir. Oseltamivir resistance was confirmed for two of the suspected cases. Neuraminidase (NA) H275Y resistant marker was found in viruses from both cases but for one it was only present in 26.2% of virus population, raising questions about the minimal percentage of resistant virus that should be considered relevant. Cross-decreased susceptibility to oseltamivir and zanamivir (2-4 IC50 fold-change) was detected on viruses from two potentially linked community patients from 2009. Both viruses harbored the NA I223V mutation. NA Y155H mutation was found in 18 statistical non-outlier viruses from 2009, having no impact on virus susceptibility. The mutations at NA N369K and V241I may have contributed to the significantly higher baseline IC50 value obtained to oseltamivir for 2010/2011 viruses, compared to viruses from the pandemic period. These results may contribute to a better understanding of the relationship between phenotype and genotype, which is currently challenging, and to the global assessment of A(H1N1)pdm09 virus susceptibility profile and baseline level to NAIs.