This paper presents an up-to-date survey of graphical tactile displays. These devices provide information through the sense of touch. At best, they should display both text and graphics (text may be ...considered a type of graphic). Graphs made with shapeable sheets result in bulky items awkward to store and transport; their production is expensive and time-consuming and they deteriorate quickly. Research is ongoing for a refreshable tactile display that acts as an output device for a computer or other information source and can present the information in text and graphics. The work in this field has branched into diverse areas, from physiological studies to technological aspects and challenges. Moreover, interest in these devices is now being shown by other fields such as virtual reality, minimally invasive surgery and teleoperation. It is attracting more and more people, research and money. Many proposals have been put forward, several of them succeeding in the task of presenting tactile information. However, most are research prototypes and very expensive to produce commercially. Thus the goal of an efficient low-cost tactile display for visually-impaired people has not yet been reached
This contribution reports the first chemoselective, stereospecific, and living polymerization of polar divinyl monomers, enabled by chiral ansa-zirconocenium catalysts through an enantiomorphic-site ...controlled coordination–addition polymerization mechanism. Silyl-bridged-ansa-zirconocenium ester enolate 2 has been synthesized and structurally characterized, but it exhibits low to negligible activity and stereospecificity in the polymerization of polar divinyl monomers including vinyl methacrylate (VMA), allyl methacrylate (AMA), 4-vinylbenzyl methacrylate (VBMA), and N,N-diallyl acrylamide (DAA). In contrast, ethylene-bridged-ansa-zirconocenium ester enolate 1 is highly active and stereospecific in the polymerization of such monomers including AMA, VBMA, and DAA. The polymerization by 1 is perfectly chemoselective for all four polar divinyl monomers, proceeding exclusively through conjugate addition across the methacrylic CC bond, while leaving the pendant CC bonds intact. The polymerization of DAA is most stereospecific and controlled, producing essentially stereoperfect isotactic PDAA with mmmm > 99%, M n matching the theoretical value (thus a quantitative initiation efficiency), and a narrow molecular weight distribution ( Đ = 1.06–1.16). The stereospecificity is slightly lower for the AMA polymerization but still leading to highly isotactic poly(allyl methacrylate) (PAMA) with 95–97% mm. The polymerization of VBMA is further less stereospecific, affording PVBMA with 90–94% mm, while the polymerization VMA is least stereospecific. Several lines of evidence from both homo- and block copolymerization results have demonstrated living characteristics of the AMA polymerization by 1. Mechanistic studies of this polymerization have yielded a monometallic coordination–addition polymerization mechanism involving the eight-membered chelating intermediate. Post-functionalization of isotactic polymers bearing the pendant vinyl group on every repeating unit via the thiol–ene “click” reaction achieves a full conversion of all the pendant double bonds to the corresponding thioether bonds. Photocuring of such isotactic polymers is also successful, producing an elastic material readily characterizable by dynamic mechanical analysis.
Doubly stranded pairs of isotactic (it-) chains of poly(methyl methacrylate) (PMMA) coiled inside of the helical cavity of syndiotactic (st-) PMMA chains generate a crystalline triple-helix ...stereocomplex, but its high brittleness limits its application. Here, we present a strategy to toughen up such stereocomplex via construction of thermoplastic elastomer (TPE)-based all-methacrylic stereoregular triblock co-polymers or toughen up such TPEs via stereocomplexation. Specifically, the stereospecific and living coordination–addition polymerization mediated by a chiral zirconocenium catalyst was utilized for the successful synthesis of isotactic ABA triblock co-polymers (it-MRM, M n up to 200 kDa, isotacticity mm > 95%) with it-PMMA as two outer complexing hard blocks and it-PRMA bearing C4–10 alkyl (R) groups as the center, noncomplexing, low-T g soft block. Physical blending of it-MRMs with st-PMMA in a 1:1 or 2:1 st/it-PMMA ratio, when crystallized from tetrahydrofuran solutions, led to stereocomplexed TPEs self-assembled into phase-segregated soft, elastic (T g from −10 to −40 °C) and high melting, stereocomplexed (T m = 192–199 °C) domains, the latter of which serves as reprocessable physical crosslinks. Characterizations of mechanical properties of the resulting stereocomplexed triblock co-polymer materials showed a significant toughening of the polymer network compared to the noncomplexed triblock co-polymer, attributed to the ability of dissipating tensile forces (necking) by the st/it-PMMA domains (tensile toughness up to 29 MJ m–3) and strain hardening by the entangled soft it-PRMA domains (elongations from 260 to 800%).
The successful synthesis of highly syndiotactic polar vinyl polymers bearing the reactive pendant vinyl group on each repeat unit, which is enabled by perfectly chemoselective and highly ...syndiospecific coordination polymerization of divinyl polar monomers developed through this work, has allowed the construction of robust cross-linked supramolecular stereocomplexes and C60 inclusion complexes. The metal-mediated coordination polymerization of three representative polar divinyl monomers, including vinyl methacrylate (VMA), allyl methacrylate (AMA), and N,N-diallyl acrylamide (DAA) by C s-ligated zirconocenium ester enolate catalysts under ambient conditions exhibits complete chemoselectivity and high stereoselectivity, thus producing the corresponding vinyl-functionalized polymers with high (92% rr) to quantitative (>99% rr) syndiotacticity. A combined experimental (synthetic, kinetic, and mechanistic) and theoretical (DFT) investigation has yielded a unimetallic, enantiomorphic-site-controlled propagation mechanism. Postfunctionalization of the obtained syndiotactic vinyl-functionalized polymers via the thiol–ene click and photocuring reactions readily produced the corresponding thiolated polymers and flexible cross-linked thin-film materials, respectively. Complexation of such syndiotactic vinyl-functionalized polymers with isotactic poly(methyl methacrylate) and fullerene C60 generates supramolecular crystalline helical stereocomplexes and inclusion complexes, respectively. Cross-linking of such complexes affords robust cross-linked stereocomplexes that are solvent-resistant and also exhibit considerably enhanced thermal and mechanical properties compared with the un-cross-linked stereocomplexes.
Time-Reversal Violation Bernabéu, José; Martínez-Vidal, Fernando
Annual review of nuclear and particle science,
10/2015, Volume:
65, Issue:
1
Journal Article
Peer reviewed
The violation of
CP
symmetry between matter and antimatter in the neutral
K
and
B
meson systems is well established, with a high degree of consistency between all available experimental measurements ...and with the Standard Model of particle physics. On the basis of the up-to-now-unbroken
CPT
symmetry, the violation of
CP
symmetry strongly suggests that the behavior of these particles under weak interactions must also be asymmetric under time reversal
T
. Many searches for
T
violation have been performed and proposed using different observables and experimental approaches. These include
T
-odd observables, such as triple products in weak decays, and genuine observables, such as permanent electric dipole moments of nondegenerate stationary states and the breaking of the reciprocity relation. We discuss the conceptual basis of the required exchange of initial and final states with unstable particles, using quantum entanglement and the decay as a filtering measurement, for the case of neutral
B
and
K
mesons. Using this method, the BaBar experiment at SLAC has clearly observed
T
violation in
B
mesons.
In this paper, we study the extraction of some analytical solutions to the nonlinear perturbed sine-Gordon equation with the long Josephson junction properties. The model studied was formed to ...observe the long Josephson junction properties separated by two superconductors. Moreover, it is also used to explain the Josephson effect arising in the highly nonlinear nature of the Josephson junctions. This provides the shunt inductances to realize a Josephson left-handed transmission line. A powerful scheme is used to extract the complex function solutions. These complex results are used to explain deeper properties of Josephson effects in the frame of impedance. Various simulations of solutions obtained in this paper are also reported.
To mimic the perioperative microenvironment where bacterial products get in contact with colorectal cancer (CRC) cells and study its impact on protein release, we exposed six CRC cell lines to ...lipopolysaccharide (LPS) and investigated the effect on the secretome using in-depth mass spectrometry-based proteomics.
Cancer cell secretome was harvested in bio-duplicate after LPS treatment, and separated in EV and soluble secretome (SS) fractions. Gel-fractionated proteins were analysed by label-free nano-liquid chromatography coupled to tandem mass spectrometry. NF-κB activation, triggered upon LPS treatment, was evaluated.
We report a CRC secretome dataset of 5601 proteins. Comparison of all LPS-treated cells with controls revealed 37 proteins with altered abundance in the SS, including RPS25; and 13 in EVs, including HMGB1. Comparing controls and LPS-treated samples per cell line, revealed 564 significant differential proteins with fold-change >3. The LPS-induced release of RPS25 was validated by western blot.
Bacterial endotoxin has minor impact on the global CRC cell line secretome, yet it may alter protein release in a cell line-specific manner. This modulation might play a role in orchestrating the development of a permissive environment for CRC liver metastasis, especially through EV-communication.
The typical layout in a piezoresistive tactile sensor arranges individual sensors to form an array with
rows and
columns. While this layout reduces the wiring involved, it does not allow the values ...of the sensor resistors to be measured individually due to the appearance of crosstalk caused by the nonidealities of the array reading circuits. In this paper, two reading methods that minimize errors resulting from this phenomenon are assessed by designing an electronic system for array reading, and the results are compared to those obtained using the traditional method, obviating the nonidealities of the reading circuit. The different models were compared by testing the system with an array of discrete resistors. The system was later connected to a tactile sensor with 8 × 7 taxels.
Tactile sensors can be used to build human-machine interfaces, for instance in isometric joysticks or handlebars. When used as input sensor device for control, questions arise related to the contact ...with the human, which involve ergonomic aspects. This paper focuses on the example application of driving a powered wheelchair as attendant. Since other proposals use force and torque sensors as control input variables, this paper explores the relationship between these variables and others obtained from the tactile sensor. For this purpose, a handlebar is instrumented with tactile sensors and a 6-axis force torque sensor. Several experiments are carried out with this handlebar mounted on a wheelchair and also fixed to a table. It is seen that it is possible to obtain variables well correlated with those provided by force and torque sensors. However, it is necessary to contemplate the influence of issues such as the gripping force of the human hand on the sensor or the different kinds of grasps due to different physical constitutions of humans and to the inherent random nature of the grasp. Moreover, it is seen that a first step is necessary where the contact with the hands has to stabilize, and its characteristics and settle time are obtained.
Viruses are the most frequent cause of respiratory disease in children. However, despite the advanced diagnostic methods currently in use, in 20 to 50% of respiratory samples a specific pathogen ...cannot be detected. In this work, we used a metagenomic approach and deep sequencing to examine respiratory samples from children with lower and upper respiratory tract infections that had been previously found negative for 6 bacteria and 15 respiratory viruses by PCR. Nasal washings from 25 children (out of 250) hospitalized with a diagnosis of pneumonia and nasopharyngeal swabs from 46 outpatient children (out of 526) were studied. DNA reads for at least one virus commonly associated to respiratory infections was found in 20 of 25 hospitalized patients, while reads for pathogenic respiratory bacteria were detected in the remaining 5 children. For outpatients, all the samples were pooled into 25 DNA libraries for sequencing. In this case, in 22 of the 25 sequenced libraries at least one respiratory virus was identified, while in all other, but one, pathogenic bacteria were detected. In both patient groups reads for respiratory syncytial virus, coronavirus-OC43, and rhinovirus were identified. In addition, viruses less frequently associated to respiratory infections were also found. Saffold virus was detected in outpatient but not in hospitalized children. Anellovirus, rotavirus, and astrovirus, as well as several animal and plant viruses were detected in both groups. No novel viruses were identified. Adding up the deep sequencing results to the PCR data, 79.2% of 250 hospitalized and 76.6% of 526 ambulatory patients were positive for viruses, and all other children, but one, had pathogenic respiratory bacteria identified. These results suggest that at least in the type of populations studied and with the sampling methods used the odds of finding novel, clinically relevant viruses, in pediatric respiratory infections are low.
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