Nutritional Value and Biofunctionalities of Two Edible Green Seaweeds (Ulva lactuca and Caulerpa racemosa) from Indonesia by Subcritical Water Hydrolysis

Caulerpa racemosa (sea grapes) and Ulva lactuca (sea lettuces) are edible green seaweeds and good sources of bioactive compounds for future foods, nutraceuticals and cosmeceutical industries. In the present study, we determined nutritional values and investigated the recovery of bioactive compounds from C. racemosa and U. lactuca using hot water extraction (HWE) and subcritical water extraction (SWE) at different extraction temperatures (110 to 230 ºC). Besides significantly higher extraction yield, SWE processes also give higher protein, sugar, total phenolic (TPC), saponin (TSC), flavonoid contents (TFC) and antioxidant activities as compared to the conventional HWE process. When SWE process was applied, the highest TPC, TSC and TFC values were obtained from U. lactuca hydrolyzed at reaction temperature 230 ºC with the value of 39.82 ± 0.32 GAE mg/g, 13.22 ± 0.33 DE mg/g and 6.5 ± 0.47 QE mg/g, respectively. In addition, it also showed the highest antioxidant activity with values of 5.45 ± 0.11 ascorbic acid equivalents (AAE) mg/g and 8.03 ± 0.06 trolox equivalents (TE) mg/g for ABTS and total antioxidant, respectively. The highest phenolic acids in U. lactuca were gallic acid and vanillic acid. Cytotoxic assays demonstrated that C. racemosa and U. lactuca hydrolysates obtained by HWE and SWE did not show any toxic effect on RAW 264.7 cells at tested concentrations after 24 h and 48 h of treatment (p < 0.05), suggesting that both hydrolysates were safe and non-toxic for application in foods, cosmeceuticals and nutraceuticals products. In addition, the results of this study demonstrated the potential of SWE for the production of high-quality seaweed hydrolysates. Collectively, this study shows the potential of under-exploited tropical green seaweed resources as potential antioxidants in nutraceutical and cosmeceutical products.

Fluid Mechanics at the Interface between a Variable Viscosity Fluid Layer and a Variable Permeability Porous Medium

The article presents a case study on the impact of thermal rehabilitation of buildings heat demand. In order to reduce specific heat consumption and, in general, heat consumption for heating and hot water preparation, measures are needed to rehabilitate and modernize the thermal protection of buildings and heating and hot water installations. The present study aims to determine the influence of thermal rehabilitation of buildings (insulation of exterior walls - in this case) making for this purpose a comparison of the values of thermal requirements before and after the thermal rehabilitation process for a building. Regarding the thermal insulation used in the case study, expanded polystyrene with a thickness of 10 cm was used for the exterior walls and mineral wool for ceiling. The main purpose of the work is to highlight the importance of thermal insulation of buildings mainly in terms of reducing energy costs and maintaining thermal comfort in homes

Physicochemical Characterization and Evaluation of the Binding Effect of Acacia etbaica Schweinf Gum in Granule and Tablet Formulations

This study is aimed at evaluating the binding effect of Acacia etbaica gum in granule and tablet formulations using paracetamol as a model drug. Some physicochemical properties of the purified gum such as pH, the presence of tannin and dextrin, solubility, viscosity, loss on drying, total ash value, water solubility index, swelling power, moisture sorption, and powder flow properties were investigated. Paracetamol granules were prepared using wet granulation method at 2%, 4%, 6%, and 8% w / w of the Acacia etbaica gum and compared with granules prepared with reference binders (PVP K-30 and Acacia BP) in similar concentrations. The granules were characterized for bulk and tapped densities, compressibility index and Hausner ratio, angle of repose, flow rate, and friability. Finally, the prepared granules were compressed into tablets and evaluated for different tablet characteristics: weight uniformity, thickness, diameter, crushing strength, tensile strength, friability, disintegration time, and in vitro release profile. The physicochemical characterization revealed that tannins and dextrin are absent in the gum, and the gum has acidic pH. Both the moisture content and total ash values were within the official limits. Furthermore, the gum was found to be soluble in cold and hot water but insoluble in organic solvent and exhibited a shear thickening viscosity profile and excellent flow properties with excellent compressibility. The granules prepared with the gum of Acacia etbaica and reference binders showed good particle size distribution and excellent flow and compressibility properties. All the prepared tablets passed pharmacopeial specifications with respect to their uniformity of weight, thickness, and disintegration time. Tablets formulated with Acacia etbaica gum and acacia BP meet the compendial specification for friability at binder concentrations more than 2%. Drug release properties of all the batches formulated with Acacia etbaica, PVP, and acacia BP complied with the pharmacopeial specification. It can be concluded that the gum of Acacia etbaica could be explored as an alternative excipient for its binder effect in granule and tablet formulations.

HOT WATER-REPELLENT SUPERHYDROPHOBIC SURFACES WITH LONG-TERM STABILITY

In this paper, we fabricate and evaluate superhydrophobic surfaces with mushroom-shaped microstructures. Using a silicon master and polymer microstructure patterning, polydimethylsiloxane (PDMS) surfaces bearing mushroom-shaped structures with five different spacing ratios are prepared and tested with water droplets of different temperatures. The fabricated PDMS surfaces demonstrate superhydrophobicity even to high-temperature water droplets with decreased surface tension. We compare the experimental data with the theoretical results calculated based on the Cassie state and Eötvös rule. Our work suggests potential applications to control wettability with liquids of various temperatures.

Brachial and carotid hemodynamic response to hot water immersion in men and women

This study sought to compare the brachial and carotid hemodynamic response to hot water immersion (HWI) between healthy young men and women. Ten women (W) and 11 men (M) (24±4 y) completed a 60 min HWI session immersed to the level of the sternum in 40°C water. Brachial and carotid artery hemodynamics (Doppler ultrasound) were measured at baseline (seated rest) and every 15 min throughout HWI. Within the brachial artery, total shear rate was elevated to a greater extent in women (+479 [+364, +594] sec-1 than men (+292 [+222, +361] sec-1) during HWI (P = 0.005). As shear rate is inversely proportional to blood vessel diameter and directly proportional to blood flow velocity, the sex difference in brachial shear response to HWI was the result of a smaller brachial diameter among women at baseline (P < 0.0001) and throughout HWI (main effect of sex: P < 0.0001) and a greater increase in brachial velocity seen in women (+48 [+36, +61] cm/sec) compared to men (+35 [+27, +43] cm/sec) with HWI (P = 0.047) which allowed for a similar increase in brachial blood flow between sexes (M: +369 [+287, +451] mL/min, W: +364 [+243, +486] mL/min, P = 0.943). In contrast, no differences were seen between sexes in carotid total shear rate, flow, velocity, or diameter at baseline or throughout HWI. These data indicate the presence of an artery-specific sex difference in the hemodynamic response to a single bout of HWI.

Influence of Cold Water Inlets and Obstacles on the Energy Efficiency of the Hot Water Production Process in a Hot Water Storage Tank

Domestic hot water preparation is one of the main sources of energy consumption in households. One of the most important elements of domestic hot water (DHW) preparation installation is the storage tank. Its design can significantly affect the efficiency of the system and energy consumption for hot water preparation. This paper presents the results of an experimental study to examine seven different designs of the cold water inlet to the storage tank and the use of two types of obstacles inside this tank placed at three different heights. The number of stratification and the energy efficiency of the system for each variant were examined. Additionally, tests were carried out for different profiles of hot water consumption in order to examine the temperature changes in the DHW tank. A system with an inlet, as an elbow facing down with a single plate, turned out to be the most advantageous variant (3–8% increase in energy efficiency compared to the basic inlet variant). An analogous analysis of the use of obstacles inside the tank showed that the most optimal solution is to place the partition, which allows the water flow on the sides of the tank, in its lower parts (energy efficiency higher by up to 15% compared to the variant without a partition). These solutions showed the highest energy efficiency for DHW production and the lowest energy demand for hot water heating in the tank among all analyzed variants.

Off-Grid Multi-Carrier Microgrid Design Optimisation: The Case of Rakiura–Stewart Island, Aotearoa–New Zealand

The establishment of the concept of sustainable, decentralised, multi-carrier energy systems, together with the declining costs of renewable energy technologies, has proposed changes in off-grid electrification interventions towards the development of integrated energy systems. Notwithstanding the potential benefits, the optimal capacity planning of such systems with multiple energy carriers—electricity, heating, cooling, hydrogen, biogas—is exceedingly complex due to the concurrent goals and interrelated constraints that must be relaxed. To this end, this paper puts forward an innovative new optimal capacity planning method for a first-of-its-kind stand-alone multiple energy carrier microgrid (MECM) serving the electricity, hot water, and transportation fuel demands of remote communities. The proposed off-grid MECM system is equipped with solar photovoltaic panels, wind turbines, a hydrogen-based energy storage system—including an electrolyser, a hydrogen reservoir, and a fuel cell—a hybrid super-capacitor/battery energy storage system, a hot water storage tank, a heat exchanger, an inline electric heater, a hydrogen refuelling station, and some power converters. The main objective of calculating the optimal size of the conceptualised isolated MECM’s components through minimising the associated lifetime costs is fulfilled by a specifically developed meta-heuristic-based solution algorithm subject to a set of operational and planning constraints. To evaluate the utility and effectiveness of the proposed method, as well as the technical feasibility and economic viability of the suggested grid-independent MECM layout, a numerical case study was carried out for Rakiura–Stewart Island, Aotearoa–New Zealand. Notably, the numeric simulation results highlight that the optimal solution presents a low-risk, high-yield investment opportunity, which is able to save the diesel-dependent community a significant 54% in electricity costs (including electrified space heating)—if financed as a community renewable energy project—apart from providing a cost-effective and resilient platform to serve the hot water and transportation fuel needs.

Polyphenols leaching and seed dormancy in carob (Ceratonia siliqua L.) in relation to hot water treatment

Carob (Ceratonia siliqua L.) is a relevant element of the Mediterranean spontaneous vegetation. Moreover, it is useful in reforestation, and it is currently re-valued for sustainable agriculture in dryland areas. However, the difficulties tied to carob propagation (mainly seed dormancy) hamper its large-scale cultivation. In this paper, the effects of four seed treatments (no treatment [control], soaking at 70 °C and 90 °C in water, or in 96% sulphuric acid) on five carob genotypes germination were studied. As compared to the very low germination of untreated seeds (0–13% germination), sulphuric acid (93–100% germination) and 90 °C water soaking (from 72 to > 90% germination in four out the five genotypes) were effective in promoting germination. Soaking at 90 °C resulted in the leaching of a higher amount of total polyphenols from the genotypes seed coat as compared to soaking at 70 °C. A significant correlation (0.75**) was ascertained between polyphenol leaching of the different genotypes and germination. These results suggest that dormancy in this species is not primarily associated with seed coat hardness, as it is generally thought, but also with the release of polyphenols. Polyphenols determination of the dormant and the few non-dormant seeds of the different genotypes also seem to confirm this hypothesis since these last showed an almost halved total polyphenols content (on average 17.0) as compared to dormant ones (34.8 mg g−1 of seed FW). Further studies may determine the polyphenols involved, but also assess new, easier to carry out, seed treatments. The important role of the galactomannans on seed germination of carob is also discussed. Finally, similar studies may enhance the knowledge of dormancy processes in other Fabaceae species whose germination is positively affected by hot water treatments.

Heat Loss Due to Domestic Hot Water Pipes

Domestic hot water (DHW) system energy losses are an important part of energy consumption in newly built or in reconstructed apartment buildings. To reach nZEB or low energy building targets (renovation cases) we should take these losses into account during the design phase. These losses depend on room and water temperature, insulation and length of pipes and water circulation strategy. The target of our study is to develop a method which can be used in the early stages of design in primary energy calculations. We are also interested in how much of these losses cannot be utilised as internal heat gain and how much heat loss depends on the level of energy performance of the building. We used detailed DHW system heat loss measurements and simulations from an nZEB apartment building and annual heat loss data from a total of 22 apartment buildings. Our study showed that EN 15316-3 standard equations for pipe length give more than a twice the pipe length in basements. We recommend that for pipe length calculation in basements, a calculation based on the building’s gross area should be used and for pipe length in vertical shafts, a building’s heating area-based calculation should be used. Our study also showed that up to 33% of pipe heat losses can be utilised as internal heat gain in energy renovated apartment buildings but in unheated basements this figure drops to 30% and in shafts rises to 40% for an average loss (thermal pipe insulation thickness 40 mm) of 10.8 W/m and 5.1 W/m. Unutilised delivered energy loss from DHW systems in smaller apartment buildings can be up to 12.1 kWh/(m2·a) and in bigger apartment buildings not less than 5.5 kWh/(m2·a) (40 mm thermal pipe insulation).