Rhizobium rubi(T): a gram-negative phytopathogenic bacterium expressing the Lewis B epitope on the outer core of its lipooligosaccharide fraction

The structure of the core oligosaccharide from the phytopathogenic bacterium Rhizobium rubi was deduced by combining information from complementary chemical approaches (alkaline and acid hydrolysis), similar to the "overlap peptide" strategy. This structure is new and it contains two main oligosaccharide backbones that differ in the substitution degree of the external Kdo unit. The relevant feature shared by both oligosaccharides is the presence of a tetrasaccharide motif that is similar to the blood group Lewis B antigen (Le(B)). This epitope differs from Le(B) in the glycosidic configuration of the glucosamine unit (alpha and not beta) and in the occurrence of acetyls substituents at O3 and/or O4 of the galactose moiety. Other notable structural features are the location of the Dha residue, the presence of a alpha-glucose unit that is linked to the inner Kdo unit, the high number of acid sugars and the highly branched core structure.     

Fundamental investigations on di-methyl ether (DME) as LPG substitute or make-up for domestic uses

The paper reports a series of experimental and model studies performed to assess the potential application of di-methyl ether (DME) as a substitute fuel in domestic appliances, commonly fed with LPG. Results are presented about combustion tests performed with pure DME and mixtures with propane and butane in variable concentrations, along with endurance and stability experiments, carried out to evaluate safety and compatibility of this fuel. The major conclusion is that a mixture of DME/LPG (DME: 15–20 vol.%) brings significant further improvement compared to pure DME.     

A collagenase-targeted multiplex PCR assay for identification of Vibrio alginolyticus, Vibrio cholerae, and Vibrio parahaemolyticus

A multiplex PCR assay using three collagenase-targeted primer pairs for the species-specific detection of Vibrio alginolyticus, Vibrio cholerae, and Vibrio parahaemolyticus was developed. The results highlight the species specificity of the three primer sets designed. Because of the increasing importance of Vibrio spp. in human foodborne diseases, molecular approaches for routine microbial screening and monitoring of clinical, environmental, and food samples also have become more important. The results of this study indicate that the gene coding for collagenase should be used as an alternative molecular target to discriminate among the three Vibrio species.     

Investigation of Salmonella enterica in Sardinian slaughter pigs: prevalence, serotype and genotype characterization

In order to improve the knowledge about the presence of Salmonella in pork meat in Sardinia (Italy), the prevalence and the sources of Salmonella at 5 pig slaughterhouses (slaughtered pigs and environment) were investigated and the isolates were characterised. A total of 462 samples were collected, 425 from pigs at slaughter and 41 from the slaughterhouse environment. Salmonella was isolated from 26/85 (30.5%) mesenteric lymph nodes, 14/85 (16.4%) colon contents, and from 12/85 (14.1%) carcasses and livers. Salmonella prevalence was 38% (8/21) in samples from surfaces not in contact with meat, and 35% (7/20) in those from surfaces in contact with meat. Thirty-one pigs were identified as carriers of Salmonella in lymph nodes and/or colon content, but of these, only 8 carcasses were positive. A total of 103 Salmonella isolates were serotyped and genotyped. Eight different serotypes were detected; the most common were S. Derby (44/103, 42.7%) and S. Typhimurium (24/103, 23.3%). The most prevalent S. Typhimurium phage type was DT193. Thirty-two isolates were found to be resistant to more than one antimicrobial (MDR). Pulse-field gel electrophoresis (PFGE) permitted the resolution of XbaI macrorestriction fragments of the Salmonella strains into 20 distinct pulsotypes. Combined application of a plasmid profiling assay (PPA) and PFGE gave useful additional information to assist in tracing the routes of Salmonella contamination in abattoirs. To reduce Salmonella prevalence some preventive measures should be encouraged: the origin of infected slaughter animals should be identified and direct and cross-contamination of carcasses should be avoided by adhering to HACCP principles in association with good hygiene procedures (GHP).     

Optimal design and seismic performance of Multi‐Tuned Mass Damper Inerter (MTMDI) applied to adjacent high‐rise buildings

The tuned mass damper inerter (TMDI) is an enhanced variant of the tuned mass damper (TMD) that benefits from the mass‐amplification effect of the inerter. Here, a multi‐TMDI (MTMDI) system (comprising more than one TMDI) linking two adjacent high‐rise buildings is presented as an unconventional seismic protection strategy. The relative acceleration response of the adjacent structures triggers large reaction forces of the inerter devices in the MTMDI, which in turn efficiently improve the seismic performance of the two buildings. By addressing a real project of two adjacent high‐rise buildings connected by two corridors equipped with the proposed MTMDI system, the displacement‐, interstory drift‐, and acceleration‐based parametric optimizations are separately performed by employing Nondominated Sorting Genetic Algorithm II (NSGA‐II) under 44 ground motions from the FEMA P695 far‐field record set. It is found that the frequency content of the seismic input has strong impact on the MTMDI mitigation performance. Adopting realistic mass ratio constraints, the optimally designed MTMDI outperforms both conventional MTMD and single TMDI in acceleration control, while it is not much effective in mitigating the displacement response due to the highly flexible nature of the high‐rise buildings, in contrast to other literature studies generally focused on low‐to‐medium rise buildings.     

A Koiter reduction technique for the nonlinear thermoelastic analysis of shell structures prone to buckling

The multi-modal Koiter method is a reduction technique for estimating quickly the nonlinear buckling response of structures under mechanical loads requiring a fine discretization. The reduced model is based on a quadratic approximation of the full model using a few linear buckling modes and their second order corrections, followed by the projection of the equilibrium equations onto the modal subspace. In this article, the method is reformulated for geometrically nonlinear thermoelastic analyses of shell structures. The starting point is an isogeometric solid-shell discretization with an accurate modeling of thermal strains, temperature-dependent materials and general temperature distributions. The equilibrium path is defined as a displacement versus temperature amplifier curve, while mechanical loads are kept constant. The strain energy nonlinearity with respect to the temperature amplifier is the main obstacle in the definition of an accurate reduced model. This task is achieved by coherent asymptotic expansions in mixed form using independent stress variables at the integration points and accurate linear buckling modes obtained by a two-point mixed eigenvalue problem. Structures made of isotropic and multi-layered composite materials, including variable angle tow laminates, are considered to show the accuracy of the proposed method.     

The determination of vitamin D3 in bovine milk by liquid chromatography mass spectrometry

A renewed international interest in vitamin D status has revealed significant deficiencies in several populations, including Australia. Vitamin D exists in two forms, cholcalciferol (D₃) and ergocalciferol (D₂). The main source of vitamin D₃ is from exposure of 7-dehydrocholesterol present in the skin to UV irradiation. However, there is an absolute requirement for vitamin D through proper dietary intake if humans live in the absence of sunlight or exclusively indoors. Bovine milk is considered to be a good dietary source of vitamin D₃, even though the levels are quite low. This paper describes robust methods using liquid chromatography–linear ion trap mass spectrometry (LC–MSⁿ) and liquid chromatography–tandem mass spectrometry (LC–MS/MS) to measure the levels of vitamin D₃ in fresh bovine milk (0.05 μg/100 ml), commercial (natural and fortified) milk samples (0.01–2 μg/100 ml) and a dairy based infant formula (8 μg/100 g), without the need for extensive clean-up procedures. The limits of quantification (LOQ) are 0.01 μg/100 ml and 0.02 μg/100 ml for LC–MSⁿ and LC–MS/MS, respectively. Recoveries of vitamin D₃ added to the samples prior to saponification were satisfactory (range 60–90%). 25-Hydroxyvitamin D₃ was not present in any of the samples analysed (LOQ = 0.01 μg/100 ml, recovery range 30–40%).     

Organic vs. traditional potato powder

In this work the profile of primary metabolites in potato (Solanum tuberosum L., cultivar Agria) grown under organic vs traditional farming system was studied, and the influence of heat processing (for producing potato powder) on nutritionally important compounds such as essential amino acids, proteins and carbohydrates was evaluated. The potato powder was obtained by means of a drum dryer using different process parameters (temperature, time and product thickness) to minimise thermal damage on the final product. The effects of these different processes were evaluated by analysing also some other quality indicators, as final moisture, colour of the powder, and rheological properties of the rehydrated puree. Moreover, because of its potential cancerogenity and genotoxicity, acrylamide content was determined in the potato powder obtained and compared with that of its main precursors (asparagine and reducing sugars). The steam pressure of 0.2 MPa and 2 r.p.m. allowed to obtain potato powder with a lower acrylamide contents and still a very low water content that caused no microbiological safety problems. This powder, both from conventional and organic farming, when rehydrated, resulted in purees with minimal nutritional losses and colour and consistency very similar to the fresh ones.     

Antimicrobial efficacy of pepsin-digested bovine lactoferrin on spoilage bacteria contaminating traditional Mozzarella cheese

The aim of this work was to check the efficacy of bovine lactoferrin (BLF) and its pepsin-digested hydrolysate (LFH) to control spoilage bacteria contaminating the governing liquid of high moisture (HM) Mozzarella cheese during cold storage. These natural substances resulted effective when tested in vitro against five potential spoilage bacteria contaminating cold-stored HM Mozzarella cheese. Among six LFH fractions, only the fraction containing lactoferricins, mainly represented by LfcinB_17–42, resulted effective against Escherichia coli K12 at the same extent of the whole pepsin-digested hydrolysate. LFH tested throughout seven days for its antimicrobial activity against the main bacterial groups growing in cold-stored commercial HM Mozzarella cheese samples delayed significantly the growth of pseudomonads and coliforms in comparison with the un-treated samples. This is the first report providing a direct evidence of the ability of LFH to inhibit the growth of cheese spoilage bacteria.     

N-Glycomics of Human Erythrocytes

Glycosylation is a complex post-translational modification that conveys functional diversity to glycoconjugates. Cell surface glycosylation mediates several biological activities such as induction of the intracellular signaling pathway and pathogen recognition. Red blood cell (RBC) membrane N-glycans determine blood type and influence cell lifespan. Although several proteomic studies have been carried out, the glycosylation of RBC membrane proteins has not been systematically investigated. This work aims at exploring the human RBC N-glycome by high-sensitivity MALDI-MS techniques to outline a fingerprint of RBC N-glycans. To this purpose, the MALDI-TOF spectra of healthy subjects harboring different blood groups were acquired. Results showed the predominant occurrence of neutral and sialylated complex N-glycans with bisected N-acetylglucosamine and core- and/or antennary fucosylation. In the higher mass region, these species presented with multiple N-acetyllactosamine repeating units. Amongst the detected glycoforms, the presence of glycans bearing ABO(H) antigens allowed us to define a distinctive spectrum for each blood group. For the first time, advanced glycomic techniques have been applied to a comprehensive exploration of human RBC N-glycosylation, providing a new tool for the early detection of distinct glycome changes associated with disease conditions as well as for understanding the molecular recognition of pathogens.