From rods to helices: evidence of a screw-like nematic phase

Evidence of a special chiral nematic phase is provided using numerical simulation and Onsager theory for systems of hard helical particles. This phase appears at the high density end of the nematic phase, when helices are well aligned, and is characterized by the C$_2$ symmetry axes of the helices spiraling around the nematic director with periodicity equal to the particle pitch. This coupling between translational and rotational degrees of freedom allows a more efficient packing and hence an increase of translational entropy. Suitable order parameters and correlation functions are introduced to identify this screw-like phase, whose main features are then studied as a function of radius and pitch of the helical particles. Our study highlights the physical mechanism underlying a similar ordering observed in colloidal helical flagella [E. Barry et al. \textit{Phys. Rev. Lett.} \textbf{96}, 018305 (2006)] and raises the question of whether it could be observed in other helical particle systems, such as DNA, at sufficiently high densities.Comment: List of authors correcte

Analytic computation of the Instantaneous Normal Modes spectrum in low density liquids

We analytically compute the spectrum of the Hessian of the Hamiltonian for a system of N particles interacting via a purely repulsive potential in one dimension. Our approach is valid in the low density regime, where we compute the exact spectrum also in the localized sector. We finally perform a numerical analysis of the localization properties of the eigenfunctions.Comment: 4 RevTeX pages, 4 EPS figures. Revised version to appear on Phys. Rev. Let

SARS-CoV-2 seroprevalence in the Vatican city state

The results of this seroprevalence analysis showed a positivity rate among individuals assisted by the internal healthcare system of the Vatican City State lower than that found in other studies on similar samples. This may be due to the small sample size and to the low number of COVID-19 cases tracked in the Vatican City State thanks to the control and prevention measures taken by the Directorate of Health and Hygiene. These measures were applied uninterruptedly through the first and second waves and included preventive measures such as hand disinfection, social distancing, use of face masks, body temperature measurement and symptom screening, as well as clinical surveillance, isolation protocols for symptomatic individuals and careful evaluation of all potential contacts

Straining at work and its relationship with personality profiles and individual consequences in healthcare workers (HCWs)

Straining is an attenuated form of mobbing, in which the continuity of vexatious actions is not driven by a discriminatory intent. With the objective of testing the possible moderating role of personality in the relationship between perceptions about straining at work and individual consequences, a correlational design research involved 374 healthcare workers (HCWs) from two Italian hospitals. The following questionnaires were administered: (1) Short Negative Acts Questionnaire (S‐NAQ), to assess discriminative actions at work); (2) the Italian version of the Big Five Inventory (BFI‐10 scale), to assess personality factors; (3) Occupational Stress Indicator (OSI), to measure psychological and physical health. Regression analysis and Structural Equation Models (SEM) were computed in order to test the relationships between variables. Perceived straining showed significant correlations with both psychological and physical health. Conscientiousness was inversely proportional to work‐related bullying (WB), as agreeableness was to personal bullying (PB). Emotional stability was negatively correlated with all the three component scales of S‐NAQ: WB, PB, and social bullying. The results seem to confirm that straining perceptions especially elicit, through emotional stability, psychological consequences. As regards the role of emotional stability in risk perceptions, it seems management has to pay thorough attention to personal factors in organizational perceptions and to straining actions

A strong glutathione S-transferase inhibitor overcomes the P-glycoprotein-mediated resistance in tumor cells - 6-(7-nitro-2,1,3-benzoxadiazol-4-ylthio)hexanol (NBDHEX) triggers a caspase-dependent apoptosis in MDR1-expressing leukemia cells

The new glutathione S-transferase inhibitor 6-(7-nitro-2,1,3-benzoxadiazol- 4-ylthio)hexanol (NBDHEX) is cytotoxic toward P-glycoprotein-overexpressing tumor cell lines, i.e. CEM-VBL10, CEM-VBL100, and U-2 OS/DX580. The mechanism of cell death triggered by NBDHEX has been deeply investigated in leukemia cell lines. Kinetic data indicate a similar NBDHEX membrane permeability between multidrug resistance cells and their sensitive counterpart revealing that NBDHEX is not a substrate of the P-glycoprotein export pump. Unexpectedly, this molecule promotes a caspase-dependent apoptosis that is unusual in the P-glycoprotein-overexpressing cells. The primary event of the apoptotic pathway is the dissociation of glutathione S-transferase P1-1 from the complex with c-Jun N-terminal kinase. Interestingly, leukemia MDR1-expressing cells show lower LC50 values and a higher degree of apoptosis and caspase-3 activity than their drug-sensitive counterparts. The increased susceptibility of the multidrug resistance cells toward the NBDHEX action may be related to a lower content of glutathione S-transferase P1-1. Given the low toxicity of NBDHEX in vivo, this compound may represent an attractive basis for the selective treatment of MDR1 P-glycoproteinpositive tumors

Novel 3D printable bio-based and biodegradable poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) microspheres for selective laser sintering applications

Selective laser sintering (SLS) has become the most popular additive manufacturing process due to its high accuracy, productive efficiency, and surface quality. However, currently there are still very few commercially available polymeric materials suitable for this technique. This research work focused on the fabrication and characterization of bio-based and biodegradable microspheres obtained by oil-in-water emulsion solvent evaporation, starting from a poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) biopolymer matrix. First, the fabrication parameters were optimized to improve the morphological, thermal, and flowability properties of the synthetized microspheres. Once the best production conditions were established, the PHBH microspheres were further used to study their effective 3D printability on an SLS 3D printer using geometries varying from simple shapes to architectures with more complex internal patterns. The results of this research revealed that PHBH has promising applicability for the SLS technique. This study undertook the first step toward broadening the range of polymeric materials for this additive manufacturing technology. These findings will contribute to a greater and wider dissemination of the SLS technique in the future, as well as they will bring this manufacturing process closer to applications, such as the biomedical sector, where the use of biodegradable and biocompatible materials can add value to the final application

A high resolution line survey of IRC+10216 with Herschel. First results: Detection of warm silicon dicarbide SiC2

We present the first results of a high-spectral-resolution survey of the carbon-rich evolved star IRC+10216 that was carried out with the HIFI spectrometer onboard Herschel. This survey covers all HIFI bands, with a spectral range from 488 to 1901GHz. In this letter we focus on the band-1b spectrum, in a spectral range 554.5-636.5GHz, where we identified 130 spectral features with intensities above 0.03 K and a signal-to-noise ratio >5. Detected lines arise from HCN, SiO, SiS, CS, CO, metal-bearing species and, surprisingly, silicon dicarbide (SiC2). We identified 55 SiC2 transitions involving energy levels between 300 and 900 K. By analysing these rotational lines, we conclude that SiC2 is produced in the inner dust formation zone, with an abundance of ~2x10^-7 relative to molecular hydrogen. These SiC2 lines have been observed for the first time in space and have been used to derive an SiC2 rotational temperature of ~204 K and a source-averaged column density of ~6.4x10^15 cm^-2. Furthermore, the high quality of the HIFI data set was used to improve the spectroscopic rotational constants of SiC2.Comment: A&A HIFI Special Issue, 201

Performance of Five Serological Tests in the Diagnosis of Visceral and Cryptic Leishmaniasis: A Comparative Study

Introduction: Leishmaniasis is a major health problem and its diagnosis still represents a challenge. Since consistent evidence on the comparison of serological methods is lacking, our work aims to compare five serological tests for the diagnosis of visceral and asymptomatic leishmaniasis in southern France, a region where leishmaniasis is endemic. Methodology: Serum samples from 75 patients living in Nice, France were retrospectively analyzed. They included patients affected by visceral leishmaniasis (VL; n = 25), asymptomatic carriers (AC; n = 25) and negative controls (n = 25). Each sample was tested using two immunochromatographic tests (ICT; IT LEISH® and TruQuick IgG/IgM®), an indirect fluorescent antibody test (IFAT) and two Western Blotting (WB; LDBio BIORAD® and an in-house method). Results: Diagnosis of VL with IFAT and TruQuick® showed the highest diagnostic performance parameters. IFAT had 100% sensitivity and specificity, while TruQuick had 96% sensitivity and 100% specificity. Finally, the two tests showed high accuracy (100% for IFAT and 98% for TruQuick) for the AC group. WB LDBio® was the only method able to detect Leishmania latent infection, with a sensitivity of 92%, and a specificity of 100%, with a Negative Predictive Value (NPV) of 93%. This performance is reflected in the high accuracy of the test. Conclusions: The data obtained with TruQuick® supports its application in the rapid diagnosis of leishmaniasis in endemic areas, a feature not shown by IFAT despite its high diagnostic performance. Regarding the diagnosis of asymptomatic leishmaniasis, the best results were obtained with WB LDBio®, confirming previous studies

A novel STK11 gene mutation (c.388dupG, p.Glu130Glyfs∗33) in a Peutz-Jeghers family and evidence of higher gastric cancer susceptibility associated with alterations in STK11 region aa 107-170

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Development of advanced Thomson spectrometers for nuclear fusion experiments initiated by laser

Thomson Spectrometers are devices capable to separate the several particle species (with distinct charge-to-mass ratio and energy) produced by the different regimes of laser-matter experiments. In this work we describe the development of advanced spectrometers for low and medium energy particles. In particular, they are suitable for protons in the 5 keV–2 MeV and 100 keV–10 MeV energy ranges, respectively. The new prototypes of spectrometers have been designed and built to have a high sensitivity and be adaptable to many experimental situations and configurations, and are tailored to the characterization of charged particles and products of nuclear fusion reactions initiated by high energy and intensity lasers. Details on the realized prototypes, on their characterization and testing, together with the first experimental results are discussed