He Chen

© 2014, National Academy of Sciences. All rights reserved.The pyroclastic aggregate concrete of Trajan's Markets, now Museo Fori Imperiali in Rome, has absorbed energy from seismic ground shaking and long-term foundation settlement for nearly two millenia while remaining largely intact at the structural scale. The scientific basis of this exceptional service record is explored through computed tomography of fracture surfaces and synchroton X-ray microdiffraction analyses of a reproduction of the standardized hydrated lime-volcanic ash mortar that binds decimeter-sized tuff and brick aggregate in the conglomeratic concrete. The mortar reproduction gains fracture toughness over 180 d through progressive coalescence of calcium-aluminum-silicate-hydrate cementing binder with Ca/ ≈ 0.8-0.9 and crystallization of strätlingite and siliceous hydrogarnet at ≥90 d, after pozzolanic consumption of hydrated lime was complete. Platey strätlingite crystals toughen interfacial zones along scoria perimeters and impede macroscale propagation of crack segments. In the 1,900-y-old mortar, C-A-S-H has low Ca/ ≈ 0.45-0.75. Dense clusters of 2- to 30-μm strätlingite plates further reinforce interfacial zones, the weakest link of modern cement-based concrete, and the cementitious matrix. These crystals formed during long-term autogeneous reaction of dissolved calcite from lime and the alkali-rich scoriae groundmass, clay mineral, and zeolite surface textures from the Pozzolane Rosse pyroclastic flow, erupted from the nearby Alban Hills volcano. The clast-supported conglomeratic fabric of the concrete presents further resistance to fracture propagation at the structural scale.

© 2015 American Chemical Society. We demonstrate straightforward fabrication of highly sensitive biosensor arrays based on field-effect transistors, using an efficient high-throughput, large-area patterning process. Chemical lift-off lithography is used to construct field-effect transistor arrays with high spatial precision suitable for the fabrication of both micrometer- and nanometer-scale devices. Sol-gel processing is used to deposit ultrathin In 2 O 3 films as semiconducting channel layers. The aqueous sol-gel process produces uniform In 2 O 3 coatings with thicknesses of a few nanometers over large areas through simple spin-coating, and only low-temperature thermal annealing of the coatings is required. The ultrathin In 2 O 3 enables construction of highly sensitive and selective biosensors through immobilization of specific aptamers to the channel surface; the ability to detect subnanomolar concentrations of dopamine is demonstrated.

Abstract: This article mainly intends to identify barriers that cause the under-representation of women in top leadership positions in higher education in Tanzania. The study comprises the sample of 250 respondents with the use of a case study research design constructed on the application of mixed methods (qualitative and quantitative). Thus, non-probability sampling was applied to qualitative data collection while probability sampling was used in quantitative data. The findings show the fundamental relationship between individual, administrative and societal factors that block women to reach the top leadership position in universities. Besides, the study has demonstrated the gender mainstreaming as the system which can be connected to adjust the hierarchical structures, methods and culture and bring the positive condition which advance gender equality. Nevertheless, as the well-known saying "Fix the holes in the pipe" goes, the variety of actions and activities are needed. Thus, in accordance with the proof from the study and individual encounters, the researcher, marked on Focused Gender Research, Capacity Development Programs, Parliamentary Charter, Setting Targets as well as Regular Monitoring and Reporting as interventions sustainable for bridging the prevailing gender leadership gap in higher education in Tanzania.

Abstract: Women under-representation in senior management post inside academic organizations remains to be an issue which needs a serious concern at national and international levels. Thus, women leaders are not in place to champion the change process. Societies, organizations and people themselves have determined that, only the males make good leaders. The gender status in the senior management positions in HE in Tanzania is virtually non-existent. Data was sourced through administered questionnaire, FGD and interview where’s senior academic and non-academic staff, together with senior university management officials were involved. Results in all seven studied universities that is SUA, MU, UDSM, JUCO, MuM and UDOM, show the positions of VC, DVCA and DVCAF to be headed by men except OUT which has a female DVCAA. Basing on the findings of this study, the researcher recommended on the transparency of procedures for recruitment and promotion, empowering women to meet employment criteria, developing a gender management system as well as mentoring and establishment of the networks for women in order to close the prevailing gender leadership gap.