MHz Unidirectional Rotation of Molecular Rotary Motors

A combination of cryogenic UV-vis and CD spectroscopy and transient absorption spectroscopy at ambient temperature is used to study a new class of unidirectional rotary molecular motors. Stabilization of unstable intermediates is achieved below 95 K in propane solution for the structure with the fastest rotation rate, and below this temperature measurements on the rate limiting step in the rotation cycle can be performed to obtain activation parameters. The results are compared to measurements at ambient temperature using transient absorption spectroscopy, which show that behavior of these motors is similar over the full temperature range investigated, thereby allowing a maximum rotation rate of 3 MHz at room temperature under suitable irradiation conditions

Phenylboronic Acids Probing Molecular Recognition against Class A and Class C beta-Lactamases

Worldwide dissemination of pathogens resistant to almost all available antibiotics represent a real problem preventing efficient treatment of infectious diseases. Among antimicrobial used in therapy, \u392-lactam antibiotics represent 40% thus playing a crucial role in the management of infections treatment. We report a small series of phenylboronic acids derivatives (BAs) active against class A carbapenemases KPC-2 and GES-5, and class C cephalosporinases AmpC. The inhibitory profile of our BAs against class A and C was investigated by means of molecular docking, enzyme kinetics and X-ray crystallography. We were interested in the mechanism of recognition among class A and class C to direct the design of broad serine \u392-Lactamases (SBLs) inhibitors. Molecular modeling calculations vs GES-5 and crystallographic studies vs AmpC reasoned, respectively, the ortho derivative 2 and the meta derivative 3 binding affinity. The ability of our BAs to protect \u392-lactams from BLs hydrolysis was determined in biological assays conducted against clinical strains: Fractional inhibitory concentration index (FICI) tests confirmed their ability to be synergic with \u392-lactams thus restoring susceptibility to meropenem. Considering the obtained results and the lack of cytotoxicity, our derivatives represent validated probe for the design of SBLs inhibitors

Genetic background of semen parameters in Italian Simmental bulls

The aim of this study was to estimate genetic parameters and investigate the genomic background of scrotal circumference and semen parameters in the Italian Simmental bulls. Scrotal circumference, number of normal spermatozoa, ejaculate volume, spermatozoa motility, and total spermatozoa were measured on 622 bulls, of which 603 had genotypes for 42,141 SNP. Variance components of scrotal circumference were estimated with an animal model that included the fixed effects of birth year, animal age, and measurement method, and the random effects of day of measurement and animal. In the model for the other traits, the scrotal circumference was added as a covariate to account for its influence on the semen parameters. A genome-wide association study was carried out using the ssGBLUP-approach. Heritabilities ranged from 0.07 +/- 0.05 (spermatozoa motility) to 0.50 +/- 0.14 (scrotal circumference). A total of 13 SNP passed the Bonferroni correction threshold and the number of significantly associated markers ranged from 1 (ejaculate volume and spermatozoa motility) to 5 (total spermatozoa). Genes already associated with reproduction parameters were retrieved close to the significant SNP. Results of the present study gave preliminary insights about the genetic determinism of semen quality in Italian Simmental bulls

Ultrafast Laser-Induced Melting of Long-Range Magnetic Order in Multiferroic TbMnO3

We performed ultrafast time-resolved near-infrared pump, resonant soft X-ray diffraction probe measurements to investigate the coupling between the photoexcited electronic system and the spin cycloid magnetic order in multiferroic TbMnO3 at low temperatures. We observe melting of the long range antiferromagnetic order at low excitation fluences with a decay time constant of 22.3 +- 1.1 ps, which is much slower than the ~1 ps melting times previously observed in other systems. To explain the data we propose a simple model of the melting process where the pump laser pulse directly excites the electronic system, which then leads to an increase in the effective temperature of the spin system via a slower relaxation mechanism. Despite this apparent increase in the effective spin temperature, we do not observe changes in the wavevector q of the antiferromagnetic spin order that would typically correlate with an increase in temperature under equilibrium conditions. We suggest that this behavior results from the extremely low magnon group velocity that hinders a change in the spin-spiral wavevector on these time scales.Comment: 9 pages, 4 figure

Group membership and racial bias modulate the temporal estimation of in-group/out-group body movements

Social group categorization has been mainly studied in relation to ownership manipulations involving highly-salient multisensory cues. Here, we propose a novel paradigm that can implicitly activate the embodiment process in the presence of group affiliation information, whilst participants complete a task irrelevant to social categorization. Ethnically White participants watched videos of White- and Black-skinned models writing a proverb. The writing was interrupted 7, 4 or 1 s before completion. Participants were tasked with estimating the residual duration following interruption. A video showing only hand kinematic traces acted as a control condition. Residual duration estimates for out-group and control videos were significantly lower than those for in-group videos only for the longest duration. Moreover, stronger implicit racial bias was negatively correlated to estimates of residual duration for out-group videos. The underestimation bias for the out-group condition might be mediated by implicit embodiment, affective and attentional processes, and finalized to a rapid out-group categorization

Experimental Testing of Dynamically Optimized Photoelectron Beams

We discuss the design of and initial results from an experiment in space-charge dominated beam dynamics which explores a new regime of high-brightness electron beam generation at the SPARC (located at INFN-LNF, Frascati) photoinjector. The scheme under study employs the natural tendency in intense electron beams to configure themselves to produce a uniform density, giving a nearly ideal beam from the viewpoint of space charge-induced emittance. The experiments are aimed at testing the marriage of this idea with a related concept, emittance compensation, We show that the existing infrastructure at SPARC is nearly ideal for the proposed tests, and that this new regime of operating photoinjector may be the preferred method of obtaining highest brightness beams with lower energy spread. We discuss the design of the experiment, including developing of a novel time-dependent, aerogel-based imaging system. This system has been installed at SPARC, and first evidence for nearly uniformly filled ellipsoidal charge distributions recorded

Sequential and Direct Two-Photon Double Ionization of D₂ at Flash

Sequential and direct two-photon double ionization (DI) of D2 molecule is studied experimentally and theoretically at a photon energy of 38.8 eV. Experimental and theoretical kinetic energy releases of D++D+fragments, consisting of the contributions of sequential DI via the D2+(1sσg) state and direct DI via a virtual state, agree well with each other