Functional trade-offs in cribellate silk mediated by spinning behavior

Web-building spiders are an extremely diverse predatory group due to their use of physiologically differentiated silk types in webs. Major shifts in silk functional properties are classically attributed to innovations in silk genes and protein expression. Here, we disentangle the effects of spinning behavior on silk performance of the earliest types of capture threads in spider webs for the first time. Progradungula otwayensis produces two variations of cribellate silk in webs: ladder lines are stereotypically combed with the calamistrum while supporting rail lines contain silk that is naturally uncombed, spun without the intervention of the legs. Combed cribellate silk is highly extensible and adhesive suggesting that the reserve warp and cribellate fibrils brings them into tension only near or after the underlying axial fibers are broken. In contrast, these three fiber components are largely aligned in the uncombed threads and deform as a single composite unit that is 5–10x stronger, but significantly less adhesive, allowing them to act as structural elements in the web. Our study reveals that cribellate silk can occupy a surprisingly diverse performance space, accessible through simple changes in spider behavior, which may have facilitated the impressive diversification of web architectures utilizing this ancient silk.Fil: Michalik, Peter. ERNST MORITZ ARNDT UNIVERSITÄT GREIFSWALD (UG);Fil: Piorkowski, Dakota. Tunghai University; ChinaFil: Blackledge, Todd A.. University of Akron; Estados UnidosFil: Ramirez, Martin Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Argentin

Comparison of Quality of Life Perceptions of Caregivers of Individuals With Intellectual Disabilities in the United States and the Czech Republic

Caregivers of individuals with disabilities in the United States have been reported to experience additional hardships than families with typical children as they attempt to balance family and work (Parish, Rose, Grinstein-Weiss, Richman, & Andrews, 2008). In this study, 31 caregivers of individuals with intellectual disabilities from the United States and 225 from the Czech Republic completed a qualitative quality of life survey. Similarities in the two groups were found in reported gains and losses from caregiving responsibilities. Differences in perceived spirituality, personal sense of peace and serenity, life optimism, ability to rejoice in life, personal life perspective, health, financial changes, changes in the family social life, feelings of enrichment, family caregiving responsibilities, and attitudes about the future were also revealed. The implications for supporting families through governmental programs and individualized services are discussed

Complex genital system of a haplogyne spider (Arachnida, Araneae, Tetrablemmidae) indicates internal fertilization and full female control over transferred sperm.

The female genital organs of the tetrablemmid Indicoblemma lannaianum are astonishingly complex. The copulatory orifice lies anterior to the opening of the uterus externus and leads into a narrow insertion duct that ends in a genital cavity. The genital cavity continues laterally in paired tube-like copulatory ducts, which lead into paired, large, sac-like receptacula. Each receptaculum has a sclerotized pore plate with associated gland cells. Paired small fertilization ducts originate in the receptacula and take their curved course inside the copulatory ducts. The fertilization ducts end in slit-like openings in the sclerotized posterior walls of the copulatory ducts. Huge masses of secretions forming large balls are detectable in the female receptacula. An important function of these secretory balls seems to be the encapsulation of spermatozoa in discrete packages in order to avoid the mixing of sperm from different males. In this way, sperm competition may be completely prevented or at least severely limited. Females seem to have full control over transferred sperm and be able to express preference for spermatozoa of certain males. The lumen of the sperm containing secretory balls is connected with the fertilization duct. Activated spermatozoa are only found in the uterus internus of females, which is an indication of internal fertilization. The sperm cells in the uterus internus are characterized by an extensive cytoplasm and an elongated, cone-shaped nucleus. The male genital system of I. lannaianum consists of thick testes and thin convoluted vasa deferentia that open into the wide ductus ejaculatorius. The voluminous globular palpal bulb is filled with seminal fluid consisting of a globular secretion in which only a few spermatozoa are embedded. The spermatozoa are encapsulated by a sheath produced in the genital system. The secretions in females may at least partly consist of male secretions that could be involved in the building of the secretory balls or play a role in sperm activation. The male secretions could also afford nutriments to the spermatozoa

Chemical Short-Range Order in Selenide and Telluride Glasses

International audienc

The Spectral Properties of Pitted Impact Deposits on Vesta as Seen by the Dawn VIR Instrument

Pitted impact deposits (PIDs) on Vesta have been shown to exhibit distinct spectral characteristics with respect to their surrounding host deposits and other typical Vestan areas regarding the first major pyroxene absorption near 0.9 μm. The PIDs, especially those in the ejecta blanket of the large crater Marcia, show higher reflectance and pyroxene band strength with respect to their impact deposit surroundings. This study complements the spectral characterization of the PIDs on Vesta with Visible and Infrared Spectrometer observations obtained by NASA’s Dawn mission. In particular, we focus on the second major pyroxene absorption near 1.9 μm. We analyze nine PIDs in the ejecta blanket of the crater Marcia, as well as PIDs within the crater-fill deposits of the craters Marcia, Cornelia, and Licinia. We find that the second pyroxene absorption behaves in similar ways as the first major pyroxene absorption. The PIDs in Marcia’s ejecta blanket show higher reflectance and pyroxene band strength with respect to their immediate impact deposit surroundings. The PIDs present in the crater-fill deposits of Marcia, Cornelia, and Licinia, however, do not show such spectral characteristics. This is also consistent with previous observations of the first pyroxene absorption band. Based on the experimental results of other studies, we speculate that the observed spectral distinctness arises from an oxidation process in the interior of impact deposits, where Fe cations migrate within their host pyroxene grains. Thus, the surfaces of (melt-bearing) impact deposits might be different from their interiors, apart from space-weathering effects

Selective ammonia oxidation over ZSM-5 zeolite: Impact of catalyst's support porosity and type of deposited iron species

[EN] In the presented studies an influence of different parameters, such as zeolite sample porosity, form of used iron source ([Fe-3(OAc)(6)O(H2O)(3)](+)oligocations or FeSO4 solutions) and method of iron species deposition (ion-exchange, impregnation), on the catalytic activity in the process of the selective catalytic oxidation of ammonia (NH3-SCO) was studied. Conventional and mesoporous ZSM-5 zeolites, obtained by desilication and modified with iron species, were analysed with respect to their textural, surface and crystalline properties (N-2-sorption, HRTEM, SEM, XRD) as well as the form of introduced Fe species (UV-vis-DRS). Ion-exchange with [Fe-3(OAc)(6)O (H2O)(3)](+) oligocations and impregnation with these oligocations and FeSO4 solutions were found as the most effective methods of the zeolite samples activation for NH3-SCO.This work was carried out in the frame of project No. 0670/IP3/2016/74 from the Polish Ministry of Science and Higher Education in the years 2016-2019. Part of the work was performed in the frame of project No. 2012/05/B/ST5/00269from the National Science Centre (Poland). U. D. acknowledges to the Spanish Government by the funding (MAT2017-82288-C2-1-P). The authors would like to acknowledge to Clariant Company for the providing of the HMFI zeolite material for the presented research.Borcuch, A.; Rutkowska, M.; Marzec, A.; Kowalczyk, A.; Michalik, M.; Moreno, J.; Díaz Morales, UM.... (2020). Selective ammonia oxidation over ZSM-5 zeolite: Impact of catalyst's support porosity and type of deposited iron species. Catalysis Today. 348:223-229. https://doi.org/10.1016/j.cattod.2019.08.054S223229348Weckhuysen, B. M., & Yu, J. (2015). Recent advances in zeolite chemistry and catalysis. Chemical Society Reviews, 44(20), 7022-7024. doi:10.1039/c5cs90100fVerboekend, D., & Pérez-Ramírez, J. (2011). Design of hierarchical zeolite catalysts by desilication. Catalysis Science & Technology, 1(6), 879. doi:10.1039/c1cy00150gRutkowska, M., Pacia, I., Basąg, S., Kowalczyk, A., Piwowarska, Z., Duda, M., … Chmielarz, L. (2017). Catalytic performance of commercial Cu-ZSM-5 zeolite modified by desilication in NH 3 -SCR and NH 3 -SCO processes. Microporous and Mesoporous Materials, 246, 193-206. doi:10.1016/j.micromeso.2017.03.017Góra-Marek, K., Brylewska, K., Tarach, K. A., Rutkowska, M., Jabłońska, M., Choi, M., & Chmielarz, L. (2015). IR studies of Fe modified ZSM-5 zeolites of diverse mesopore topologies in the terms of their catalytic performance in NH3-SCR and NH3-SCO processes. Applied Catalysis B: Environmental, 179, 589-598. doi:10.1016/j.apcatb.2015.05.053Macina, D., Piwowarska, Z., Góra-Marek, K., Tarach, K., Rutkowska, M., Girman, V., … Chmielarz, L. (2016). SBA-15 loaded with iron by various methods as catalyst for DeNOx process. Materials Research Bulletin, 78, 72-82. doi:10.1016/j.materresbull.2016.02.026Rutkowska, M., Duda, M., Macina, D., Górecka, S., Dębek, R., Moreno, J. M., … Chmielarz, L. (2019). Mesoporous Beta zeolite functionalisation with FexCry oligocations; catalytic activity in the NH3SCO process. Microporous and Mesoporous Materials, 278, 1-13. doi:10.1016/j.micromeso.2018.11.003Miller, J. T., Glusker, E., Peddi, R., Zheng, T., & Regalbuto, J. R. (1998). Catalysis Letters, 51(1/2), 15-22. doi:10.1023/a:1019072631175Kowalczyk, A., Borcuch, A., Michalik, M., Rutkowska, M., Gil, B., Sojka, Z., … Chmielarz, L. (2017). MCM-41 modified with transition metals by template ion-exchange method as catalysts for selective catalytic oxidation of ammonia to dinitrogen. Microporous and Mesoporous Materials, 240, 9-21. doi:10.1016/j.micromeso.2016.11.002Chmielarz, L., & Jabłońska, M. (2015). Advances in selective catalytic oxidation of ammonia to dinitrogen: a review. RSC Advances, 5(54), 43408-43431. doi:10.1039/c5ra03218kThommes, M., Kaneko, K., Neimark, A. V., Olivier, J. P., Rodriguez-Reinoso, F., Rouquerol, J., & Sing, K. S. W. (2015). Physisorption of gases, with special reference to the evaluation of surface area and pore size distribution (IUPAC Technical Report). Pure and Applied Chemistry, 87(9-10), 1051-1069. doi:10.1515/pac-2014-1117Qi, G., & Yang, R. T. (2005). Selective catalytic oxidation (SCO) of ammonia to nitrogen over Fe/ZSM-5 catalysts. Applied Catalysis A: General, 287(1), 25-33. doi:10.1016/j.apcata.2005.03.00

Potential control under thin aqueous layers using a Kelvin Probe

Kelvin Probes can be modified to control as well as monitor potential. The design and operation of two different Kelvin Probe Potentiostats (KPPs) are described in this paper. One approach uses a permanent magnet and double coil to oscillate the needle at a fixed frequency, an AC backing potential, and software analysis and control schemes. This technique can also control the distance between the tip and sample, thereby tracking the topography of the sample. Both KPPs were used to make measurements on Type 304L stainless steel under thin layers of electrolyte. Cathodic polarization curves exhibited a limiting current density associated with oxygen reduction. The limiting current density varied with solution layer thickness over a finite range of thickness. Anodic polarization curves on 304L in a thin layer of chloride solution resulted in pitting corrosion. The breakdown potential did not vary with solution layer thickness. However, the thin layer was observed to increase in volume remarkably during pit growth owing to the absorption of water from the high humidity environment into the layer with ionic strength increased by the pit dissolution. The open circuit potential (OCP) and solution layer thickness were monitored during drying out of a thin electrolyte layer. Pitting corrosion initiated, as indicated by a sharp drop in the OCP, as the solution thinned and increased in concentration.This work was supported in part by the Office of Science and Technology and International (OST&I), Office of Civilian Radioactive Waste Management (OCRWM), US Department of Energy (DOE). The work is carried out as part of the DOE Multi-University Corrosion Cooperative under Cooperative Agreement DE-FC28-04RW12252