Fourier Transform Rheology: A New Tool to Characterize Material Properties

Liquid multiphase systems such as polymer blends or emulsions are ubiquitous in many applications, including plastic production, food processing, pharmaceutical and cosmetic production. When the constituents of the multiphase system are incompatible the phases are immiscible, and, depending on their relative amount, the microstructure can consist of droplets in a matrix, elongated fibrils or a co-continuous structure (Utracki, 2003) as schematically shown in Figure 1. The morphology of the liquid multiphase system is important in the applications as it strongly affects processing properties, and the properties of the final products. With the term “morphology” we here indicate not only the overall form or shape of the physical structure of the system, but also the distribution and orientation of the phases, the interfacial area, and the volume of the interphase. Hence, a profound knowledge of the relation between processing parameters, material properties and morphology is essential to optimize the performances of the liquid multiphase systems.Substantial efforts were done in the last decades to set up experimental protocols aimed at evaluating the morphological properties of polymer blends and emulsions via rheological measurements. So far, the most reliable strategy for morphological characterization through rheological measurements is based on the dynamic small amplitude oscillatory shear (SAOS) experiment: the samples are subjected to small amplitude shearing oscillations, and the measured shear stress response is used to gain information on the blend properties (e.g. Palierne, 1990). Here, we present an alternative technique we have recently proposed to characterize the liquid two-phase system morphology. This methodology is based on Large Amplitude Oscillatory Shear (LAOS) flows. This kind of analysis is often referred in the literature as Fourier Transform Rheology (FTR) (Wilhelm et al., 1998), since the stress response is usually analyzed in the Fourier domain. It will be shown that Fourier Transform Rheology possesses a high sensitivity in the characterization of the morphology, thus allowing evaluation of properties that might otherwise be hardly appreciated with traditional linear methodologies

A Chemometric Approach to Assess the Rheological Properties of Durum Wheat Dough by Indirect FTIR Measurements

Rheological measurements and FTIR spectroscopy were used to characterize different doughs, obtained by commercial and monovarietal durum wheat flours (Cappelli and Karalis). Rheological frequency sweep tests were carried out, and the Weak Gel model, whose parameters may be related to gluten network extension and strength, was applied. IR analysis mainly focused on the Amide III band, revealing significant variations in the gluten network. Compared to the other varieties, Karalis semolina showed a higher amount of α-helices and a lower amount of β-sheets and random structures. Spectroscopic and rheological data were then correlated using Partial Least Squares regression (PLS) coupled with the Variable Importance in Projection (VIP) technique. The combined use of the techniques provided useful insights into the interplay among protein structures, gluten network features, and rheological properties. In detail, β-sheets and α-helices protein conformations were shown to significantly affect the gluten network\u27s mechanical strength

Broadband Dielectric Spectroscopy (BDS) investigation of molecular relaxations in durum wheat dough at low temperatures and their relationship with rheological properties

Broadband Dielectric Spectroscopy (BDS) was used to study the dielectric relaxation processes of semolina doughs. The dielectric properties were analyzed as a function of water content, and, additionally, the effects of NaCl presence and semolina characteristics were investigated. The dough was prepared using three different varieties of semolina. BDS measurements were conducted using a custom-made Rheo-dielectric tool composed of a Broadband Dielectric/Impedance Spectrometer connected to a strain-controlled rheometer. The temperature range investigated was from −135 °C to 25 °C, with a step of 5 °C, while the frequency range was 10$_{−1}$ – 10$_7$ Hz. Dielectric spectroscopy turned out to be a valuable technique for dough characterization. It is capable to distinguish the carbohydrates contribution and the different interactions between water and dough components. Moreover, this unique combination allows assessing correlations between rheological and dielectric properties, like the compliance of dough as a function of the relaxation processes and the influence of semolina components

Brewer´s Spent Grain to Bioethanol Through a Hybrid Saccharification and Fermentation Process

Brewer´s spent grain, without being pre-treated, has been investigated for bioethanol production through a Hybrid Saccharification and Fermentation (HSF) process with high solid loading. HSF experiments were performed in a 2 L bioreactor where Cellic ® CTec2 was used to perform the enzymatic hydrolysis, and Saccharomyces Cerevisiae was used for the fermentation. The reaction environment was first set to favour saccharification. Then, after 26 h, the reactor was inoculated with the yeast. The results evidenced the presence of glucose, xylose, and arabinose after the conversion of cellulose and hemicellulose and a rapid depletion of glucose after adding the yeast. The pentoses were also consumed, but with a much slower reaction rate. Almost four hours after adding the yeast, the amount of ethanol had reached a maximum and then began to decrease as microorganisms began to use ethanol as a substrate after glucose depletion. The obtained ethanol yield, evaluated with respect to the theoretical value, was equal to 72%

Rheology of Conductive High Reactivity Carbonaceous Material (HRCM)-Based Ink Suspensions: Dependence on Concentration and Temperature

The present case study reports a shear rheological characterization in the temperature domain of inks and pastes loaded with conductive High Reactivity Carbonaceous Material (HRCM) consisting mainly of few-layers graphene sheets. The combined effect of filler concentration and applied shear rate is investigated in terms of the shear viscosity response as a function of testing temperature. The non-Newtonian features of shear flow ramps at constant temperature are reported to depend on both the HRCM load and the testing temperature. Moreover, temperature ramps at a constant shear rate reveal a different viscosity-temperature dependence from what is observed in shear flow ramps while maintaining the same filler concentration. An apparent departure from the well-known Vogel-Fulcher-Tamman relationship as a function of the applied shear rate is also reported

The Role of Formulation and Working Parameters on the Rheological Properties of Semolina Doughs for the Production of Carasau Bread

Carasau bread is a typical Sardinian baking product, with great commercial potential, due to its long shelf life. Nowadays, its production is performed, in most cases, in small or medium size factories, where the working conditions and quality properties of the product are set on an empirical basis. Thus, the processing know-how lacks quantitative information, and the product is still far from standardization. As a result, industrial-scale manufacturing is hindered. The literature presents some studies devoted to better explaining the effect of semolina doughs' main constituents (gluten, starch, etc.) on their rheological properties or to infer the latter through in-line measurement. However, it is still necessary to understand the role of each working parameter in conditioning the dough rheology. This work investigated the role of five working parameters: yeast amount, salt amount, water temperature, kneading time, and leavening time. The water amount was kept constant to avoid covering other effects because its role can be predominant in most cases. A Design of Experiments (DOE) was performed, in order to plan the experimental campaign. First, the dough samples were tested through a parallel plate rheometer (Anton Paar, model MCR 102), applying both creep and frequency sweep tests. Moreover, the same samples were subjected to Texture Profile Analysis (TPA) to highlight possible correlations between theoretical rheological model parameters and TPA ones, which can be obtained in shorter times, so being more suitable for process monitoring purposes

Vaccines against human HER2 prevent mammary carcinoma in mice transgenic for human HER2

INTRODUCTION: The availability of mice transgenic for the human HER2 gene (huHER2) and prone to the development of HER2-driven mammary carcinogenesis (referred to as FVB-huHER2 mice) prompted us to study active immunopreventive strategies targeting the human HER2 molecule in a tolerant host. METHODS: FVB-huHER2 were vaccinated with either IL-12-adjuvanted human HER2-positive cancer cells or DNA vaccine carrying chimeric human-rat HER2 sequences. Onset and number of mammary tumors were recorded to evaluate vaccine potency. Mice sera were collected and passively transferred to xenograft-bearing mice to assess their antitumor efficacy. RESULTS: Both cell and DNA vaccines significantly delayed tumor onset, leading to about 65% tumor-free mice at 70 weeks, whereas mock-vaccinated FVB-huHER2 controls developed mammary tumors at a median age of 45 weeks. In the DNA vaccinated group, 65% of mice were still tumor-free at about 90 weeks of age. The number of mammary tumors per mouse was also significantly reduced in vaccinated mice. Vaccines broke the immunological tolerance to the huHER2 transgene, inducing both humoral and cytokine responses. The DNA vaccine mainly induced a high and sustained level of anti-huHER2 antibodies, the cell vaccine also elicited interferon (IFN)-gamma production. Sera of DNA-vaccinated mice transferred to xenograft-carrying mice significantly inhibited the growth of human HER2-positive cancer cells. CONCLUSIONS: Anti-huHER2 antibodies elicited in the tolerant host exert antitumoral activity

Cyclic Vomiting Syndrome in Children

Cyclic Vomiting Syndrome (CVS) is an underdiagnosed episodic syndrome characterized by frequent hospitalizations, multiple comorbidities, and poor quality of life. It is often misdiagnosed due to the unappreciated pattern of recurrence and lack of confirmatory testing. CVS mainly occurs in pre-school or early school-age, but infants and elderly onset have been also described. The etiopathogenesis is largely unknown, but it is likely to be multifactorial. Recent evidence suggests that aberrant brain-gut pathways, mitochondrial enzymopathies, gastrointestinal motility disorders, calcium channel abnormalities, and hyperactivity of the hypothalamic-pituitary-adrenal axis in response to a triggering environmental stimulus are involved. CVS is characterized by acute, stereotyped and recurrent episodes of intense nausea and incoercible vomiting with predictable periodicity and return to baseline health between episodes. A distinction with other differential diagnoses is a challenge for clinicians. Although extensive and invasive investigations should be avoided, baseline testing toward identifying organic causes is recommended in all children with CVS. The management of CVS requires an individually tailored therapy Management of acute phase is mainly based on supportive and symptomatic care. Early intervention with abortive agents during the brief prodromal phase can be used to attempt to terminate the attack. During the interictal period, non-pharmacologic measures as lifestyle changes and the use of reassurance and anticipatory guidance seem to be effective as a preventive treatment. The indication for prophylactic pharmacotherapy depends on attack intensity and severity, the impairment of the QoL and if attack treatments are ineffective or cause side effects. When children remain refractory to acute or prophylactic treatment, or the episode differs from previous ones, the clinician should consider the possibility of an underlying disease and further mono- or combination therapy and psychotherapy can be guided by accompanying comorbidities and specific sub-phenotype. This review was developed by a joint task force of the Italian Society of Pediatric Gastroenterology Hepatology and Nutrition (SIGENP) and Italian Society of Pediatric Neurology (SINP) to identify relevant current issues and to propose future research directions on pediatric CV

Azimuthal anisotropy of charged jet production in root s(NN)=2.76 TeV Pb-Pb collisions

We present measurements of the azimuthal dependence of charged jet production in central and semi-central root s(NN) = 2.76 TeV Pb-Pb collisions with respect to the second harmonic event plane, quantified as nu(ch)(2) (jet). Jet finding is performed employing the anti-k(T) algorithm with a resolution parameter R = 0.2 using charged tracks from the ALICE tracking system. The contribution of the azimuthal anisotropy of the underlying event is taken into account event-by-event. The remaining (statistical) region-to-region fluctuations are removed on an ensemble basis by unfolding the jet spectra for different event plane orientations independently. Significant non-zero nu(ch)(2) (jet) is observed in semi-central collisions (30-50% centrality) for 20 <p(T)(ch) (jet) <90 GeV/c. The azimuthal dependence of the charged jet production is similar to the dependence observed for jets comprising both charged and neutral fragments, and compatible with measurements of the nu(2) of single charged particles at high p(T). Good agreement between the data and predictions from JEWEL, an event generator simulating parton shower evolution in the presence of a dense QCD medium, is found in semi-central collisions. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Peer reviewe

Performance of the ALICE experiment at the CERN LHC

ALICE is the heavy-ion experiment at the CERN Large Hadron Collider. The experiment continuously took data during the first physics campaign of the machine from fall 2009 until early 2013, using proton and lead-ion beams. In this paper we describe the running environment and the data handling procedures, and discuss the performance of the ALICE detectors and analysis methods for various physics observables