Micro-encapsulation of asphalt rejuvenators using melamine-formaldehyde

Asphalt pavement roads are exposed to traffic loading and natural elements such as rain, sunlight and oxidation, which result in decreasing their relaxation capabilities and the initiation of cracks. Innovative maintenance techniques such as developing microcapsules with rejuvenators have emerged in order to reverse the aging process in asphalt binder. The objectives of this study were to assess the effectiveness of an asphalt rejuvenator to reverse the aging process in asphalt binder and to develop a microencapsulation procedure for the tested asphalt rejuvenator. Properties such as size, shell thickness and morphology of the prepared microcapsules were evaluated by varying the production parameters, i.e. agitation rate, heating temperature, and Ethyl Methyl Acrylate (EMA) concentration. Three binder types were considered in the experimental program, two virgin asphalt binders that were aged in the laboratory and a binder extracted from Reclaimed Asphalt Pavement (RAP). Based on the results of the experimental program, it was concluded that the binder Performance Grade (PG) 70-22 was partially restored at both high and low temperature grades with the use of the rejuvenator. In contrast, the low temperature grade of the binder PG 76-22 and the high temperature grade of the RAP binder were restored with the use of the tested rejuvenator product. Microcapsules containing the rejuvenator were synthesized and a characterization process was conducted based on microcapsule properties such as diameter, shell thickness and morphology of the prepared microcapsules

Rheological properties of asphalt binder modified with recycled asphalt materials and light-activated self-healing polymers

Ultraviolet (UV), light-activated, self-healing polymers are an emerging technology that was proposed to enhance the elastic behavior of asphalt binder, while improving its self-healing properties. The objective of this study was to evaluate the effects of self-healing polymer on the rheological properties of binder blends prepared with or without recycled asphalt materials. Binder blends were prepared with two different binders (PG 67-22 and PG 70-22M), with or without recycled asphalt materials, and 5% self-healing polymer (Oxetane-substituted Chitosan-Polyurethane). High-Pressure Gel Permeation Chromatography (HP-GPC) results showed an increase in High Molecular Weight (HMW) components in the binder with an increase in stiffness through the addition of recycled materials. A further increase was observed with the addition of self-healing polymer. Fourier Transform Infrared Spectroscopy (FTIR) confirmed High-Pressure Gel Permeation Chromatography (HP-GPC) results with an increase in the carbonyl index. Furthermore, the addition of recycled materials led to an increase in the high-temperature grade and the low-temperature grade of the binder blends, while the self-healing polymer did not have a significant effect on the PG-grade. Overall, the addition of self-healing polymer led to an increase in stiffness and an improvement in the rutting performance, while it did not have a positive effect on low-temperature cracking performance. For unmodified binder (PG 67-22), self-healing polymer incorporation improved the elastic and fatigue cracking properties of the binder. However, when it was added to a polymer-modified binder (PG 70-22M) and/or binder blends containing recycled asphalt materials, the potential of this material was low to negative on the low temperature and fatigue cracking performances

How simulation modelling can help reduce the impact of COVID-19

Modelling has been used extensively by all national governments and the World Health Organisation in deciding on the best strategies to pursue in mitigating the effects of COVID-19. Principally these have been epidemiological models aimed at understanding the spread of the disease and the impacts of different interventions. But a global pandemic generates a large number of problems and questions, not just those related to disease transmission, and each requires a different model to find the best solution. In this article we identify challenges resulting from the COVID-19 pandemic and discuss how simulation modelling could help to support decision-makers in making the most informed decisions. Modellers should see the article as a call to arms and decision-makers as a guide to what support is available from the simulation community

A survey on environmental effects of shrimp pond culture effluents in Gwatar area (Sistan & Blouchestan)

Present project was conducted in shrimp farm located in east of Chabahar in Sistan and Balouchestan province.Twentieth sampling stations at three locations (i.e. 2 stations in supply channel,13 stations in drainage channel and 5 stations in Gwatar Gulf) were selected to determine physical and chemical factors such as; temperature, salinity, dissolved oxygen, pH, nitrate, nitrite, ammonia, phosphate and biological parameters for example Chlorophyll a, phytoplankton and zooplankton. Sampling was conducted once a month from March 2003 until January 2004. The results revealed different bioenvironmental area in the three locations (i.e. supply channel, drainage channel and Gwatar Gulf) over the study period. Concentration of salinity ,pH , nitatr ,nitrite ,ammonia and chlorophyll a in drainage channel were more than supply channel and Gawtar Gulf. While concentation dissolved oxygen and phosphate were in drainage channel less than Gawtar Gulf.Also, sediment with small grain size (clay and silt) caused uptake phosphate and amount phosphate decreased in drainage channel. Considering with lack of environment standards in Iran shrimp effluent, data compared with others countries standard. Results showed that with considerable farm area, value of temperature, salinity, dissolved oxygen and pH were in permit range in Gwatar Gulf while concentation nitrate, phosphate and chlorophyll a were sometimes more than permit range that could cause plankton bloom. Also, Gwatar Gulf were influence monsoon. Nitate, phosphate, chlorophyll a and phytoplankton increased in gwatar Gulf.Regards with that postmonsoon was simultaneus with shrimp harvest.Therefore, increase some parameters could be caused from shrimp effluent or postmonsoon. Thirty four phytoplankton genus were identified including diatoma, dinoflagellate, cyanophyta and chlorophyta. In each area maxiumum percentage of phytoplankton were belonged to diatoma (63%) in supply channel, cyanophyta (51.7%) in drainage channel and dinoflagellate (94.5%) in Gwatar Gulf.Amount and range chemical and physical factors and plankton composition were different in drainage channel, supply channel and Gwatar Gulf. Cyanophyta could grow more in drainage channel.Percentage of aboundance and diversity of phytoplankton changed in 2002 inrelation to years ago( before shrimp culture, 2000 year and 2001 year) specially in Gwatar Gulf. Mainly percentage of zooplankton were copepoda and thintinida respectively.Diversity zooplankton decreased ratio to years ago. In drainage channel, abundance total of phytoplankton and zooplankton were more than Gwatar Gulf and supply channel

Laboratory Testing of Self-Healing Polymer Modified Asphalt Mixtures Containing Recycled Asphalt Materials (RAP/RAS)

The objective of this study was to evaluate the efficiency of an innovative light-induced self-healing polymers in enhancing the durability of asphalt mixtures and improving its self-healing properties. Mixtures were prepared using two different binders, with and without recycled materials, and self-healing polymer. Results showed that the addition of recycled asphalt material to mixtures prepared with an unmodified binder negatively affected the healing recovery at room temperature. Furthermore, Self-healing properties of the mixtures were improved by increasing the healing temperature. The addition of 5% self-healing polymer to the control mixture, followed by UV light exposure resulted in an increase in self-healing properties of the mixtures prepared with PG 67-22 binder. Semi-Circular Bending (SCB) test results showed that the incorporation of self-healing polymer and 48 h of UV light exposure improved the cracking resistance. Loaded-Wheel Test (LWT) results showed that the self-healing polymer caused an increase in the rut depth of the samples prepared with an unmodified binder. However, the final rut depth was less than the acceptable rutting performance. Thermal-Stress Restrained Specimen Test (TSRST) test results showed that self-healing polymer improved the low temperature cracking performance of the mixtures

Developmental phosphoproteomics identifies the kinase CK2 as a driver of Hedgehog signaling and a therapeutic target in medulloblastoma

A major limitation of targeted cancer therapy is the rapid emergence of drug resistance, which often arises through mutations at or downstream of the drug target or through intrinsic resistance of subpopulations of tumor cells. Medulloblastoma (MB), the most common pediatric brain tumor, is no exception, and MBs that are driven by sonic hedgehog (SHH) signaling are particularly aggressive and drug-resistant. To find new drug targets and therapeutics for MB that may be less susceptible to common resistance mechanisms, we used a developmental phosphoproteomics approach in murine granule neuron precursors (GNPs), the developmental cell of origin of MB. The protein kinase CK2 emerged as a driver of hundreds of phosphorylation events during the proliferative, MB-like stage of GNP growth, including the phosphorylation of three of the eight proteins commonly amplified in MB. CK2 was critical to the stabilization and activity of the transcription factor GLI2, a late downstream effector in SHH signaling. CK2 inhibitors decreased the viability of primary SHH-type MB patient cells in culture and blocked the growth of murine MB tumors that were resistant to currently available Hh inhibitors, thereby extending the survival of tumor-bearing mice. Because of structural interactions, one CK2 inhibitor (CX-4945) inhibited both wild-type and mutant CK2, indicating that this drug may avoid at least one common mode of acquired resistance. These findings suggest that CK2 inhibitors may be effective for treating patients with MB and show how phosphoproteomics may be used to gain insight into developmental biology and pathology

Publisher Correction: Notch1 regulates the initiation of metastasis and self-renewal of Group 3 medulloblastoma.

The original version of this Article omitted Suzana A. Kahn, Siddhartha S. Mitra & Samuel H. Cheshier as jointly supervising authors. This has now been corrected in both the PDF and HTML versions of the Article

Perceived discrimination and health-related quality of life among Arabs and Jews in Israel: A population-based survey

<p>Abstract</p> <p>Background</p> <p>Studies have shown that perceived discrimination may be associated with impaired health. The aim of this study was to assess the levels of perceived discrimination on the basis of origin and ethnicity and measure the association with health in three population groups in Israel: non-immigrant Jews, immigrants from the former Soviet Union, and Arabs.</p> <p>Methods</p> <p>A cross sectional random telephone survey was performed in 2006 covering 1,004 Israelis aged 35-65; of these, 404 were non-immigrant Jews, 200 were immigrants from the former Soviet Union and 400 were Arabs, the final number for regression analysis was 952. Respondents were asked about their perceived experiences with discrimination in seven different areas. Quality of life, both physical and mental were measured by the Short Form 12.</p> <p>Results</p> <p>Perceived discrimination on the basis of origin was highest among immigrants. About 30% of immigrants and 20% of Arabs reported feeling discriminated against in areas such as education and employment. After adjusting for socioeconomic variables, discrimination was associated with poor physical health among non-immigrant Jews (OR = 0.42, CI = 0.19, 0.91) and immigrants (OR = 0.51, CI = 0.27, 0.94), but not among Arabs. Poor mental health was significantly associated with discrimination only among non-immigrant Jews (OR = 0.42, CI = 0.18, 0.96).</p> <p>Conclusions</p> <p>Perceived discrimination seemed high in both minority populations in Israel (Arabs and immigrants) and needs to be addressed as such. However, discrimination was associated with physical health only among Jews (non-immigrants and immigrants), and not among Arabs. These results may be due to measurement artifacts or may be a true phenomenon, further research is needed to ascertain the results.</p