Mechanisms of germ cell formation during zebrafish embryogenesis

In metazoans, the germ fate is acquired during embryogenesis either via oocyte-inherited cytoplasmic aggregates or via chemical induction from the surrounding embryonic cells. Most of the model organisms, including Caenorhabditis elegans, Drosophila melanogaster, Xenopus laevis and Danio rerio, rely on maternal determinants necessary to generate the germ line of the offspring. Although it has been largely established that germ determinants are required for the formation of germ cells, the specific molecular mechanisms driving the onset of the germ line are still unclear. Germ granules have been implicated in transcriptional inhibition contributing to skipping somatic differentiation. Also, epigenetic reprogramming of the embryonic germ line has been shown in several model organisms. However, little is known about the role of the germ plasm in transcription and epigenetics. Here, we show that the germ plasm and the epigenetic landscape of zebrafish primordial germ cells (PGCs) are tightly linked. The early germ line shows similar transcriptional timing, transcriptomic and chromatin profiles with the rest of the embryo and the germ fate is gradually acquired during the first day of development. A PGC-like chromatin profile is acquired while germ plasm re-localises within the cells and PGCs and somatic cells undergo significant epigenetic and transcriptional divergence. By performing time series of chromatin and transcript profiles in the PGCs, we could identify candidate PGC-specific cis-regulatory elements and transcripts. We detect both hypermethylation and chromatin compaction around putative developmental enhancers indicating that the germ fate is acquired avoiding lineage differentiation. Finally, to link epigenetic dynamics to germ plasm behaviour, we inhibited the translation of Tudor Domain 7 (Tdrd7), a germ-plasm-localised protein involved in structural organisation of the germ granules. The mutant embryos reprogram the PGC-specific chromatin state and resemble the somatic cells, suggesting that the germ plasm is primarily responsible for epigenetically preserving the pluripotent state of the PGCs

Biofouling Prevention of Ancient Brick Surfaces by TiO2-Based Nano-Coatings

Brick constitutes a significant part of the construction materials used in historic buildings around the world. This material was used in Architectural Heritage for structural scope, and even for building envelopes. Thus, components made of clay brick were subjected to weathering for a long time, and this causes their deterioration. One of the most important causes for deterioration is biodeterioration caused by algae and cyanobacteria. It compromises the aesthetical properties, and, at a later stage, the integrity of the elements. In fact, traditional products used for the remediation/prevention of biofouling do not ensure long-term protection, and they need re-application over time. The use of nanotechnology, especially the use of photocatalytic products for the prevention of organic contamination of building facades is increasing. In this study, TiO2-based photocatalytic nano-coatings were applied to ancient brick, and its efficiency towards biofouling was studied. A composed suspension of algae and cyanobacteria was sprinkled on the bricks' surface for a duration of twelve weeks. Digital Image Analysis and colorimetric measurements were carried out to evaluate algal growth on specimens' surfaces. Results show that photocatalytic nano-coating was able to inhibit biofouling on bricks' surfaces. In addition, substrata (their porosity and roughness) clearly influences the adhesion of algal cells

Moisture buffering "active" devices for indoor humidity control: preliminary experimental evaluations

Abstract In recent building practice, obligations of legislation relating to Nearly Zero Energy Buildings (NZEB) (European Directives 2002/91/EC and 2010/31/EU) are carried out mainly by high thermal resistance and total air tightness of the envelope, in order to minimize heat dispersions by conduction and infiltration as much as possible. These measures cause new ways of heat and moisture exchange in the building envelope and are likely to create high internal moisture load with consequences for durability of materials and inhabitants' comfort and health. Improvement in the thermal performance of the envelope can then lead to the paradoxical need for high energy consumption in order to handle the vapor peaks indoors by using mechanical ventilation equipments. Even if with HVAC devices it is possible to provide an acceptable indoor climate, there is still a need to develop more passive and less energy intensive methods to moderate the indoor environment in NZEB. In recent decades many authors have focused on a promising strategy related to the use of "moisture buffering" materials which dampen indoor humidity variations without additional energy costs. Nevertheless, many internal finishing materials commonly used at present are still not highly performant or lead to problems of hysteresis. In the present study, we propose an alternative solution, which is the design of a moisture buffering "active" device, to be integrated in a part of the building envelope, which is able to measure the relative humidity indoors and control its loads by a low-energy-consumption fan system. The humidity control performance of the device has been dynamically tested in a climate chamber and has been compared with traditional "passive" material samples in order to measure the Moisture Buffering Value (MBV) according to the DTU test method. Experimental results showed that "passive" samples have high moisture buffering values [MBV = 6.12 g/(m2% RH)] and do not lead to hysteresis phenomena. The MBV measured in the "active" devices increased up to 29%, which predicts promising future applications for low-energy-consumption indoor humidity control

Uncertainty impact on decisions related to historical buildings energy retrofit

Decisions concerning energy retrofit of historical buildings should be based on a complex set of parameters, ranging from not-tangible to tangible values, such as the historical and the cultural value, the expected costs and benefits, the environmental impacts. The tangible values, such as the monetary costs and benefits, are often prioritized considering their measurability, however neglecting that they are frequently affected by important uncertainties (related e.g. to the evolution of the macro-economic scenario, to the building components maintenance and replacement needs, etc.). This fact can lead to improper design choices and consequently to the risk of losing part of the building tangible or not-tangible value. For this reason, it is necessary to improve decision-making processes and tools, also considering uncertainty and sensitivity analysis as part of the design process related to the energy retrofit of historical buildings. In this paper we show the impact of different assumptions regarding future possible macro-economic scenarios on the monetary benefits of a historic building renovation intervention. A “probabilistic” Life Cycle Costing tool, developed through the software environment for statistical computing “R”, has been used to evaluate the parameters mostly influencing the global costs of the typical energy retrofit measures applied to a building case-study. Results demonstrate how the uncertainties related to the economic parameters are the most influencing the output variance. The uncertainties related to the building periodic maintenance and the energy costs are also prevailing on those related to the initial investment costs

How to restart? An agent-based simulation model towards the definition of strategies for COVID-19 "second phase" in public buildings

Restarting public buildings activities in the "second phase" of COVID-19 emergency should be supported by operational measures to avoid a second virus spreading. Buildings hosting the continuous presence of the same users and significant overcrowd conditions over space/time (e.g. large offices, universities) are critical scenarios due to the prolonged contact with infectors. Beside individual's risk-mitigation strategies performed (facial masks), stakeholders should promote additional strategies, i.e. occupants' load limitation (towards "social distancing") and access control. Simulators could support the measures effectiveness evaluation. This work provides an Agent-Based Model to estimate the virus spreading in the closed built environment. The model adopts a probabilistic approach to jointly simulate occupants' movement and virus transmission according to proximity-based and exposure-time-based rules proposed by international health organizations. Scenarios can be defined in terms of building occupancy, mitigation strategies and virus-related aspects. The model is calibrated on experimental data ("Diamond Princess" cruise) and then applied to a relevant case-study (a part of a university campus). Results demonstrate the model capabilities. Concerning the case-study, adopting facial masks seems to be a paramount strategy to reduce virus spreading in each initial condition, by maintaining an acceptable infected people's number. The building capacity limitation could support such measure by potentially moving from FFPk masks to surgical masks use by occupants (thus improving users' comfort issues). A preliminary model to combine acceptable mask filters-occupants' density combination is proposed. The model could be modified to consider other recurring scenarios in other public buildings (e.g. tourist facilities, cultural buildings).Comment: 21 pages, 16 figures; submitted to Building and Environmen

Measuring Occupants' Behaviour for Buildings' Dynamic Cosimulation

Measuring and identifying human behaviours are key aspects to support the simulation processes that have a significant role in buildings' (and cities') design and management. In fact, layout assessments and control strategies are deeply influenced by the prediction of building performance. However, the missing inclusion of the human component within the building-related processes leads to large discrepancies between actual and simulated outcomes. This paper presents a methodology for measuring specific human behaviours in buildings and developing human-in-the-loop design applied to retrofit and renovation interventions. The framework concerns the detailed building monitoring and the development of stochastic and data-driven behavioural models and their coupling within energy simulation software using a cosimulation approach. The methodology has been applied to a real case study to illustrate its applicability. A one-year monitoring has been carried out through a dedicated sensor network for the data recording and to identify the triggers of users' actions. Then, two stochastic behavioural models (i.e., one for predicting light switching and one for window opening) have been developed (using the measured data) and coupled within the IESVE simulation software. A simplified energy model of the case study has been created to test the behavioural approach. The outcomes highlight that the behavioural approach provides more accurate results than a standard one when compared to real profiles. The adoption of behavioural profiles leads to a reduction of the discrepancy with respect to real profiles up to 58% and 26% when simulating light switching and ventilation, respectively, in comparison to standard profiles. Using data-driven techniques to include the human component in the simulation processes would lead to better predictions both in terms of energy use and occupants' comfort sensations. These aspects can be also included in building control processes (e.g., building management systems) to enhance the environmental and system management

COVID-19 impact on end-user's maintenance requests. A text mining approach

COVID-19 pandemic changed our way of working, limiting the usual physical attendance of working spaces. Despite the drastic reduction in the number of daily users due to the pandemic restrictions, working buildings were often kept open to provide services to internal and external users. Pandemic obliged to change operation and maintenance (O&M) plans, due to the increase of ventilation requirements and the reduction of other types of services, with a strong impact on cost and management. Now the pandemic is reducing its effects and is time to question the future asset of buildings’ O&M plans, based on the pandemic lesson. Data collected by Computerized Maintenance Management Systems (CMMS) during COVID-19 then become an important source of understanding the future management of working places. End-users’ maintenance requests are usually expressed by natural language, then a text mining approach can be a useful tool to discover hidden knowledge from unstructured data stored in CMMS. This study applies text mining methods, including sentiment analysis, to the field of building maintenance, with the scope to evaluate how COVID-19 changed some aspects of the facility management process, including users’ perception

design and performance assessment of building counter walls integrating moisture buffering active devices

Abstract The use of building materials with high moisture buffering capacity is a well-recognized strategy to moderate the variation of indoor moisture loads. Many researchers investigated the ability and potential of finishing materials and furniture for the reduction of the amplitudes of indoor relative humidity by characterising their Moisture Buffering Value. Nevertheless, the recent and widespread building practice, which is increasingly trying to reduce the air permeability and thermal transmittance of the envelope, is likely to even worsening indoor humidity conditions, with consequences for durability of materials and inhabitants' comfort and health. Very performing materials are then needed to act as buffering and quickly dampen high moisture loads. This paper proposes the design of a building internal counter wall equipped with an "active" moisture buffering device. This is able to measure the indoor relative humidity and consequently increase the adsorbing capacity of a porous material through an air-flow. Experimental activities were carried out on different prototypes with the combination of granular Sepiolite with two different pore structures and nonwoven fabrics. The devices effectiveness in terms of MBV has been dynamically tested in a climate chamber according to the DTU Nordtest method. Different "activation" times against several humidity levels were set in order to assess the best solution in different scenarios