Last glacial maximum hydro-climate and cyclone characteristics in the Levant: a regional modelling perspective

Proxy-based hydro-climatic reconstructions over the Levant suggest enhanced water availability during the Last Glacial Maximum (LGM) compared to present-day conditions. To date, the governing hypothesis is that additional water availability may be directly linked to increased Cyprus Low frequency and intensity over the region. However, this paradigm has not been tested in a modelling framework. With this aim, we analyzed results from a weather type classification algorithm and regional climate simulations. The weather type classification is applied to ERA5 Reanalysis data for present-day (1979-2018) and two PMIP3/PMIP4 pre-industrial and LGM model runs. Dynamical downscaling of the two models with the regional WRF model shows that the present hydro-climate can largely be reproduced. Our simulations suggest that both evaporation and precipitation were lower in the LGM compared to pre-industrial conditions, and that their relative changes can thus most likely explain the additional water availability during that time. Indeed, evaporation in the eastern Mediterranean is reduced to a higher degree (~-33%) as compared to precipitation (~-20%) during the LGM. Particularly, lower evaporation during LGM summer may have sustained the year-round wetter conditions in the Levant. In addition, we find significant changes in Cyprus Low characteristics for the LGM. The simulated daily precipitation associated with Cyprus Lows is significantly lower than pre-industrial values (reduction of 26 - 29%), whereas the wind intensity is stronger (increase of 7 - 8%). Finally, a significant increase in Cyprus Low frequency during LGM winter is likely (+22%). Indeed, our findings are in line with a plethora of proxy-based reconstructions, and provide a reinterpretation of the driving mechanism of water availability, i.e., strong changes in evaporation rather than precipitation. This study places projected hydro-climatic drying of the Levant in a long timescale perspective. As such, it improves our understanding of the physical processes influencing the hydrological cycle in this vulnerable region, situated on the border between sub-tropical and mid-latitude climatic zones.

Remdesivir: Mechanism of Metabolic Conversion from Prodrug to Drug

Background: Remdesivir (GS-5734) has emerged as a promising drug during the challenging times of COVID-19 pandemic. Being a prodrug, it undergoes several metabolic reactions before converting to its active triphosphate metabolite. It is important to establish the atomic level details and explore the energy profile of the prodrug to drug conversion process. Methods: In this work, Density Functional Theory (DFT) calculations were performed to explore the entire metabolic path. Further, the potential energy surface (PES) diagram for the conversion of prodrug remdesivir to its active metabolite was established. The role of catalytic triad of Hint1 phosphoramidase enzyme in P-N bond hydrolysis was also studied on a model system using combined molecular docking and quantum mechanics approach. Results: The overall energy of reaction is 11.47 kcal/mol exergonic and the reaction proceeds through many steps requiring high activation energies. In the absence of a catalyst, the P-N bond breaking step requires 41.78 kcal/mol, which is reduced to 14.26 kcal/mol in a catalytic environment. Conclusion: The metabolic pathways of model system of remdesivir (MSR) were completely explored completely and potential energy surface diagrams at two levels of theory, B3LYP/6-311++G(d, p) and B3LYP/6-31+G(d), were established and compared. The results highlight the importance of an additional water molecule in the metabolic reaction. The P-N bond cleavage step of the metabolic process requires the presence of an enzymatic environment.

Adsorption Inhibitor Role in a Constant Salinity Surfactant-Polymer CSSP Flooding Design for an Offshore Field Application

A base chemical flooding formulation using alkaline-surfactant-polymer (ASP) has been developed for application in offshore environments. The formulation uses combination of conventional alkali (sodium carbonate) with amphoteric surfactant. The field is currently under waterflooding using sea water as injection water. However, since alkali is incompatible with divalent ions in sea water, an alternative formulation using seawater with no additional water treatment is also being developed and considered for application. The alternative formulation uses combination of alkyl propoxy sulfate (APS) and alkyl ethoxy sulfate (AES). Coreflood recovery performance of both formulations is similar. Without alkali, high surfactant adsorption becomes major concern for the alternative formulation. Thus, an adsorption inhibitor (AI) agent – polyacrylic acid type, is being considered as an additive to address this concern. While AI showed potential in reducing surfactant adsorption and improving oil recovery efficiency, it can also increase overall cost for the surfactant in sea water chemical formulation. Hence, the merit to apply AI was not clearly observed.

Can Additional Water a Day Keep the Cysts Away, in Patients with Polycystic Kidney Disease?

Can Additional Water a Day Keep the Cysts Away, in Patients with Polycystic Kidney Disease?

Geopolymers Reinforced with Natural Fibers: A Comparison among Different Sources

The performance of different natural fibers (hemp, kenaf and bamboo) used to formulate composites with an alkali-activated matrix based on metakaolin is evaluated. Short fibers were randomly dispersed up to about 3% of the binder weight, and the fresh and cured properties of the derived composites were determined. Up to the investigated fraction, it is still possible to obtain adequate workability without the supply of additional water or additives. Upon modification with fibers, the mechanical behavior changes from completely brittle to pseudoplastic with increased toughness. The flexural strength increases by up to 80% at the highest bamboo amount and up to 20% for kenaf. Hemp fibers have a negligible effect on flexural strength but strongly improve the materials’ toughness. Moreover, the addition of fibers does not change the manner in which the material interacts with moisture. Indeed, the water uptake of the modified samples was comparable to that of the unmodified samples, and the composites showed a decreased rate of water diffusion as the amount of fiber increased.

Assessing the potential for managed aquifer recharge (MAR) of the Cape Flats Aquifer

This paper discusses the potential use of ‘managed aquifer recharge’ (MAR) in Cape Town to provide additional water supplies to the city that are fit-for-purpose. The paper investigates the feasibility of implementing MAR by simulating the artificial recharge of winter stormwater into the Cape Flats Aquifer (CFA), an extensive sandy, unconfined aquifer that covers most of metropolitan Cape Town’s urban landscape. The objective is to assess the storage capacity and supply potential of two MAR sites by modelling various scenarios in order to determine the feasibility of MAR as a viable strategy for achieving improved water security by augmenting groundwater water supply. The selected scenarios demonstrated that MAR could be used to minimise the risk of seawater intrusion and maximise the amount of water available for abstraction from the CFA. Six MAR scenarios provided strong evidence to suggest that there is sufficient storage capacity within the CFA for using stormwater to improve the wellfield yield in two regions of the CFA and which can sustainably yield approximately 18 Mm3 per year. The study concluded that the use of stormwater or treated wastewater could be deliberately used to recharge the CFA and as a viable option in support of the City of Cape Town’s intention to establish a water-resilient city by 2030.

Response of Water Balance Components to Changes in Soil Use and Vegetation Cover Over Three Decades in the Eastern Amazon

Impacts on global water resources may be intensifying due to the growing and differentiated forms of land use and occupation, which influence the water cycle and thus the maintenance of life. In the Amazon, the effect may be even worse, as it is one of the world's most vulnerable regions to these changes. This work aimed to analyze the response of the components of the water balance to changes in land use and cover in the Eastern Amazon over three decades (1980–2013). First, soil texture maps were prepared. These combined with the classes of use in each decade let us estimate the values of storage and variation in storage (ΔS) of water in the soil. The behavior of the components of the water balance [precipitation, potential evapotranspiration, actual evapotranspiration (E), and ΔS] were analyzed according to the Budyko model on the annual scale as a function of the aridity and evaporative indices. For the seasonal scale, a new parameter (y0) was introduced to explicitly represent the additional water available for E, in addition to instantaneous precipitation. The seasonality of the rains and the seasonal dynamics of storage were directly incorporated into the model developed, which allowed us to understand what the dominant control factors of water balance are. In the decade from 2000 to 2009, the remaining forest cover is only 48.91%, while the cover formed by pasture is 50.47%, meaning the water storage capacity in the soil decreased 8.1%. In the 1990s, to 1999, precipitation shows a reduction, probably as a reflection of the very strong events of La Niña and El Niño (1988–1989 and 1997–1998). Observing the sum of the surface area of water bodies in the region and the relationship of forest vs. pasture, it is possible to infer that the elevation in evapotranspiration is more related to the increase in evaporation due to the increase in the pasture area than to the reduction transpiration due to forest loss, reinforcing the hypothesis that evapotranspiration increases with pasture area.

The Role of Structure and Interactions in Thermoplastic Starch–Nanocellulose Composites

Composite films were fabricated by using cellulose nanocrystals (CNCs) as reinforcement up to 50 wt% in thermoplastic starch (TPS). Structure and interactions were modified by using different types (glycerol and sorbitol) and different amounts (30 and 40%) of plasticizers. The structure of the composites was characterized by visible spectroscopy, Haze index measurements, and scanning electron microscopy. Tensile properties were determined by tensile testing, and the effect of CNC content on vapor permeability was investigated. Although all composite films are transparent and can hardly be distinguished by human eyes, the addition of CNCs somewhat decreases the transmittance of the films. This can be related to the increased light scattering of the films, which is caused by the aggregation of nanocrystals, leading to the formation of micron-sized particles. Nevertheless, strength is enhanced by CNCs, mostly in the composite series prepared with 30% sorbitol. Additionally, the relatively high water vapor permeability of TPS is considerably decreased by the incorporation of at least 20 wt% CNCs. Reinforcement is determined mostly by the competitive interactions among starch, nanocellulose, and plasticizer molecules. The aging of the films is caused by the additional water uptake from the atmosphere and the retrogradation of starch.

Water Management in UGM for Resilient and Healthy Campus

Water management is one of the most challenging aspects of campus management. With a large number on campus population and limited water resources, water management is essential for achieving a resilient and healthy campus. In this paper, we explain two targets in UGM water management: water efficiency and water conservation. Both objectives are significantly related; however, each goal has a different approach to the method for the design approach and strategies in the implementations. Water efficiency is included in building new buildings and retrofitting the existing ones. Meanwhile, water conservation is implemented to calculate potential alternative water resources in UGM, including water treatment, to produce freshwater as an additional water supply. We also explain how water management is implemented in UGM from the highest Directorate to the lowest units. Through our method and best practices in UGM, we hope our paper could be a reference for other universities who want to implement a water management program.