Safety production of coalmines is a task of top priority which plays an important role in guaranteeing, supporting and promoting the continuous development of the coal industry. Since traditional wireless sensor networks (WSNs) cannot fully meet the requirements of comprehensive environment monitoring of underground coalmines, wireless multimedia sensor networks (WMSNs), enabling the retrieval of multimedia information, are introduced to realize fine-grained and precise environment surveillance. In this paper, a framework for designing underground coalmine WMSNs based on Multi-Band Orthogonal Frequency-Division Multiplexing Ultra-wide Band (MB-OFDM-UWB) is presented. The selection of MB-OFDM-UWB wireless transmission solution is based on the characteristics of underground coalmines. Network structure and design challenges are analyzed first, which is the foundation for further discussion. Then, key supporting technologies and open research areas in different layers are surveyed, and we provide a detailed literature review of the state of the art strategies, algorithms and general solutions in these issues. Finally, other research issues like localization, information processing, and network management are discussed. Safety production of coalmines is a task of top priority which plays an important role in guaranteeing, supporting and promoting the continuous development of coal industry. It is also a key part of the state work safety. Implementing the strategy of “Prospering the nation, the coal industry and the safety production by science” and establishing the long-term mechanism of coalmine safety production are essential for China’s coalmine industry .In recent years, China has made considerable progress in coalmine safety production, but the situation is still severe which draws higher demands for the coalmine industry. To ensure the safe operation of coalmines and reduce the number of accidents and casualties to the maximum, the systems for coalmine monitoring, early warning and disaster relief have urgent demands for wireless video surveillance, wireless voice communication, underground environment monitoring and personnel positioning . Video sWireless sensor networks (WSNs), which have outstanding advantages of easy configuration, flexibility to shrink or expand the monitoring range, strong fault-tolerance and mobility, are going to play an important role in monitoring and analyzing the dynamic, hostile, unfamiliar and unexplored environment . HoweverOn the basis of WSNs, wireless multimedia sensor networks (WMSNs) are new types of sensor networks which enable perception of multimedia content such as video and audio streams, and images ,4,5. TheUsing WMSNs to monitor the environment of coalmines attracts interests of many researchers in recent years. For instance, strategies of deploying WMSNs in underground coalmine have been put forward by Han and Yang ,8. Sun eIn this article, a detailed survey about WMSNs for underground coalmine is conduct to discuss the main research challenges and the state of the art supporting technologies for the development of WMSNs for coalmine. The main purposes of our paper are twofold: to make a summary of the application status of WSNs and WMSNs in the underground coalmine, and to present a framework and related open issues for designing underground coalmine WMSNs based on MB-OFDM-UWB scheme. Since the MB-OFDM-UWB scheme has great potentials to promote the performance of the existing monitoring and communication system, we believe that our work can serve as a point of inspiration for readers wishing to start researching into this area or researchers who try to design innovative emergency communication and monitoring system.The rest of this article is organized as follows. According to demands for comprehensive monitoring, the wireless multimedia monitoring system for underground coalmine based on Multi-Band Orthogonal Frequency-Division Multiplexing UWB (MB-OFDM-UWB) WMSNs mainly provides the following functions: (1) video surveillance for underground environments; (2) wireless voice communication; (3) multi-parameter monitoring for underground coalmine; and (4) localization of sensor nodes and targets.On the basis of the previous research and experiment works of Zhang et al.  and Han As shown in Specifically, for branch working zone, there are two basic methods of mining coalmines: longwall mining and room-and-pillar mining . In longWMSNs are deployed in different local regions, and can be easily added in or removed off at any time according to varieties of monitoring requirements. Local regions have the characteristics of regional decentralization and small relevance to each other, and thus need to be monitored separately. Besides, monitoring contents and nodes configurations may vary dramatically. For instance, from the perspective of monitoring scale, the number of sensor nodes deployed in some local regions is small while that of other regions may be very large. Furthermore, the deployment of WMSNs for underground coalmine is first planned and fulfilled by workers, and that means it is a deterministic deployment instead of a random one which are usually used by WSNs. To ensure the safe operation of the WMSNs and the whole monitoring system, the system needs to be maintained and updated periodically.Sensor nodes are the foundation of constructing WMSNs and all the protocols and algorithms concerning about sensor networks make sense when applied on sensor nodes. At present, the wireless sensor nodes designed or produced are generally classified into two categories: the first are nodes which take the general-purpose microprocessors as core components and use the design methods of embedded systems; the second are nodes designed using the platforms for designing specified device like FPGA and ASIC, such as PicoRadio , Multi-RThe difference between the hardware of sensor nodes in WMSNs and that in traditional WSNs is that the sensor nodes of WMSNs are equipped with CMOS sensors that can ubiquitously capture images and videos, and processors that have stronger processing capacities. However, the basic components of sensor nodes in WMSNs and those in WSNs are basically the same, which can be divided into four parts as shown in In the design of hardware, the prevalent technology of applying extended interfaces to connect sensors is used, which enhances the universality and flexibility of the hardware platform. From the perspective of processors, the sensor nodes can be divided into two categories. The first category uses the high-end processors represented by ARM, mostly supports dynamic voltage scaling (DVS) or dynamic frequency scaling (DFS), and has strong video processing capabilities. The Stargate  developeThe wireless transceiver unit uses 802.15.4 compliant Chipcon CC2420 radio, whose maximum transmission rate is 250 kbps, seeming powerless for transmitting video streams. Then, in some application scenarios that have high real-time requirements, 802.11b wireless cards are used. However, this increases the energy consumption and seems impractical. Further research work and techniques need to be introduced to solve the problem of high bandwidth demand and resource constraints.With different sensing modules embedded into sensor nodes, variable parameters including temperature ,19, humiIn recent years, the techniques of applying WSN into underground coalmines have been investigated. In ,22, multAt present, as mentioned in the previous section, the research work and application of WSN for underground coalmine are mainly based on ZigBee protocol in IEEE 802.15.4 standard. The basic requirement of the data rate for transferring CIF video streams is still higher than the date rate of ZigBee. Obviously, the maximum transmission rate of ZigBee could not satisfy the higher requirements of conducting multimedia surveillance in coalmine. On the other side, introducing Wi-Fi into coalmine seems a good choice for performing video surveillance, taking the advantages that Wi-Fi has a long transmission distance and high data rates . NeverthA comparison among UWB, Wi-Fi, and ZigBee from the aspects of typical transmission distance, frequency, data rate, power consumption and complexity is presented in Above all, constructing wireless multimedia monitoring network for underground coalmine based on MB-OFDM-UWB wireless transmission technology is a promising and ideal way to realize coalmine multimedia surveillance, making full use of UWB’s characteristics of high speed, low power consumption and so on, and underground coalmine’s characteristic of open frequency resource.As a new-generation wireless communication technique, the ultra-wide band (UWB) is the key technique to realize high speed wireless communication . UWB proThe initial UWB technique did not use the carrier but the ns-ps level non-sinusoidal pulses with very short duration for data transmission . BecauseThe MB-OFDM-UWB solution divides the whole bandwidth into several sub-bands, which will enable data processing over a much narrower bandwidth. Additionally, it has also inherited the advantages of the multi-carrier modulation, such as the abilities to efficiently eliminate the inter-symbol interference (ISI) owing to multi-path propagation, and the complexity of the receivers. Therefore, the MB-OFDM-UWB solution is well-suited for the multi-path propagation environment like coalmine. The communication environment for underground coalmine is a typical representation of the confined space. The walls of laneways bring in plenty of refraction and scattering paths, resulting in the complex multi-path propagation of signals in laneways . The delConsequently, choosing the modulation scheme of MB-OFDM-UWB as the wireless transmission mode for wireless multimedia sensors in the underground coalmine environment , can realize the integration of video surveillance for coalmine safety, wireless voice communication, underground environment monitoring and personnel positioning. Moreover, it will become a great means to promote the abilities of the coalmine safety monitoring, the early warning, and the rescue and relief of disasters.The overall design of the WMSNs for underground coalmine is introduced in the previous section and the main focus is on the modulation scheme in physical layer. As for the WMSNs, there are some technologies which are also very important for its performance in underground coalmine. These technologies are called key supporting techniques, mainly including coverage-enhancing algorithms, media access control (MAC), routing mechanism, cross-layer optimization, and video encoding. All these key supporting techniques have been discussed to construct an integrated monitoring system based on the WMSNs for underground coalmine. Before further discussion of each section, a block diagram organized in layer-specific structure and giving the main research issues for coalmines is shown in Due to the extreme and changing conditions of coalmines, deploying conventional wired networks is difficult and costly. For WMSNs, a successful deployment could enable tremendous savings in operational expenses because of enhanced communications and quality-of-service (QoS). Nevertheless, a hostile radio frequency environment  and interference generated by heavy equipment are still challenges for engineers when considering deployment or coverage problems.Coverage-enhancing issues, which are about how to deploy sensor nodes to maximize the coverage range with the guarantee of QoS, are basic problems for researching WMSNs . MeasuriBased on the monitoring requirements, the sensor nodes of the WMSNs for underground coalmine can be classified into three types: video or image sensors, voice communication sensors and environment parameter monitoring sensors. Thus, the WMSNs for underground coalmine, made up by these sensors, are heterogeneous and multifunctional coverage networks. Currently, the research work on the coverage issues of WMSNs is concentrating on coverage-enhancing algorithms of homogeneous networks. Area coverage, target coverage, barrier coverage and connectivity coverage are main topics for the coverage issues. The coverage issue of heterogeneous networks, by contrast, is more difficult for research because we should consider the heterogeneous characteristics of sensor networks such as the different sensing models, the different information content of monitoring data and the difference between sensors’ resources or capacities . FurtherThe deployment problem of the monitoring sub-net mainly lies in the video surveillance sensors and environment parameter monitoring sensors. The voice communication sensors can be deployed according to the requirements of voice communication, thus not being our focus. Owing to the difference between the functions and the qualities of these two sensors, research work should be conducted separately. Preliminary research work on the deployment problem of WMSNs in confined space like underground coalmine have been shown in ,8. As shGuaranteeing the bandwidth for transmitting multimedia data over wireless links, while ensuring the high transmission quality with limited sensor capabilities, are key factors for the network design of WMSNs. Media access control protocols, as the direct controller of sending and receiving all the data packets and the controlling packets over wireless channels, define the regulations of how to share media between the sensors to ensure the satisfactory network performance. Therefore, applying MAC protocols to efficiently use wireless channels are one of the crucial factors for guaranteeing the communication of WMSNs.MAC protocols for WMSNs can be mainly categorized into three types: contention-based protocols, contention-free single channel protocols, and contention-free multi-channel protocols ,41. ContSome of the existing studies ,42,43,44Recent years have seen many newly designed MAC protocols for WMSN that made effort to support multimedia services and satisfy the QoS requirements of users. In the paper , a new QWhen designing MAC protocols for coalmine WMSNs, tradeoffs between the additional overhead of contention-free protocols and the energy savings realized through collision elimination of contention-based protocols need to be explored to definitively ascertain whether a single MAC protocol or a hybrid one should be used . Meanwhi(1)QoS: Most of the routing protocols for traditional WSNs mainly aim at minimizing the energy consumption, but introducing the multimedia contents like videos and images into WMSNs makes QoS a crucial issue. When designing routing protocols, not only the energy consumption, scalability and robustness of the network, but also real-time and reliable transmission of multimedia data need to be taken into consideration.(2)Sensing models: Sensors in WMSNs are universally directional, e.g., video sensors, which make the sensing models or coverage models distinct from those of traditional WSNs. Distinctions in sensing models or coverage models will directly affect the design of network structure and routing protocols.(3)Data aggregation: For the sake of reducing the amount of data and lowing power consumption, a majority of the routing protocols for WSNs have adopted data aggregation mechanism. In WMSNs, sensors nodes have strong directionality and transmits multimedia data which are information-rich and time-sensitive. The redundancy and the relevance of multimedia data need to be considered when aggregating data.Just like traditional WSNs, the routing protocols, whose function is establishing and maintaining data transmission paths between any two nodes that need to communicate with each other, are also key part of researching WMSNs. However, the design of the routing mechanism for WMSNs is quite different from that for traditional WSNs in the following aspects:At present, based on the design principles of QoS guarantee, energy minimization or network lifetime maximization, stateless routing and so on, routing protocols of WMSNs including SPEED , MPMPS  achieve high compression efficiency to effectively limit bandwidth and energy consumption, with the guarantee for the quality of video surveillance; (2) have low complexity and power consumption to enable multimedia encoders to be embedded in sensor devices and to prolong the lifetime of sensor nodes; and (3) provide robust and error-resilient coding of source data. For typical state-of-the-art video compression standards, such as MPEG, H.263 and H.264, which employ the motion estimation functionality at encoders, the encoder is five to ten times more complex than the decoder . Thus, tDistributed source coding (DSC) adopts the technique of combining intra-frame encoding with inter-frame decoding, which leverages knowledge of the source statistics at the decoder and reduces the complexity of coding at the encoder, making itself extremely suitable for WMSNs . DSC hasThough great effect has been achieved by these distributed video coding techniques, most of the recent research papers are still confined to discussing the theory of coding and decoding itself, leaving lots of problems to be explored and discussed in the area of combining the practical application of WMSNs. Since video distortions, felt by end users, depend on source coding and channel coding, multimedia encoding techniques for coalmine WMSNs should take the factors like channel coding techniques for coalmine environment into consideration. Besides, the environments of coalmines are generally with poor light and more coal dust, which have great influence on the quality of video surveillance, video streams in coalmines present different statistic features from traditional surficial applications, and these features should be utilized by encoding techniques. In addition, network topology may also effect the implementation of the Wyner-Ziv video coding algorithm . Therefore, the video surveillance techniques should be associated with the MB-UWB wireless transmission technique, the transmission characteristics of wireless channels in coalmine tunnel, and the temporal and spatial relationship between video sensors in coalmine. Moreover, the distributed video coding techniques should be designed to meet the requirements of video surveillance for underground coalmine.Although most of the key supporting technologies have been shown in the aforementioned layer-specific discussion, additional issues should be addressed to make the structure of underground coalmine WMSNs an integrated one. Some other important issues like UWB localization, video localization, and information processing and network management are considered in this section.Besides the application sceneries mentioned above, WMSNs for underground coalmine will also plays an important role in production automation, people or asset tracking, security assisting or rescuing and underground coalmine robot navigation. Localization techniques for underground coalmine include the techniques for locating wireless sensor node itself and locating monitored targets, where the latter one is especially essential for underground coalmine applications such as target monitoring, robot navigation, and motion analysis for miners.For the self-localization problem of sensor nodes, since UWB technique is adopted in the physical layer of the communication stack, thus the problem turns to a UWB based localization problem of sensor nodes. As for the UWB localization technique which adopts impulse radio (IR), centimeter-level or even millimeter-level ranging accuracy is theoretically possible, due to the extremely short duration of transmitted pulses and the strong ability of time-resolving. Specifically, the UWB ranging system based on impulse radio technology regularly figures out the distance between sending and receiving end, by estimating the time of arrival (TOA) of the earliest component of received signals. In recent years, IR-UWB based TOA position estimation algorithms have been well studied ,60, inclNevertheless, the algorithms are mainly concentrating on IR-UWB technique, while sensor nodes in underground coalmine WMSNs use MB-UWB technique in their physical layer which is quite different from IR-UWB. Thus, the current IR-UWB localization techniques could not be applied in MB-UWB based system. The localization problem for the sensor nodes in underground coalmine should considering the structure of network and MB-UWB techniques in physical layer, leading to corresponding localization algorithms.The sensing model for video sensors in WMSNs is based on directional sensing model which utilizes perspective projection relationship of cameras, which differs remarkably from the omni-directional sensing model for traditional WSNs. Thus, there are significant differences between the target localization algorithms of the two. In recent years, the target localization problem has received considerable attention and research work in the area of WMSNs. An object localization scheme for WMSNs, which can be run on a single camera node by utilizing the size of the object on the frame obtained from frame differencing and the monocular vision imaging model, has been proposed in . In 62]62], the From the existing research work, it can be seen that the study on target localization techniques for WMSNs should be related with specific conditions in the acquiring methods, contents, types and quantity of information. Likewise, the target localization techniques for underground coalmine WMSNs should also take the network structure, characteristics of monitoring scenes, MB-UWB wireless transmission mode, and processing capacity of sensor nodes into consideration, as well as be designed by combining a distributed source coding scheme and a target capturing scheme. With the limitations in energy, processing capacity and other resources of sensor nodes, introducing information processing techniques into the acquiring, transmitting and displaying information processing techniques in WMSNs is an effective way to lift the QoS performance of multimedia service. Among these information processing techniques, compression coding, filtering and data fusion are the most common ones.Compression coding techniques compress image, audio and video streams which are tremendous in data amount, saving the bandwidth resource of network while providing high-quality multimedia service. Filtering techniques can filter out parts of data which are not interesting for observers and not valuable for monitoring results from raw sensing data, thus gaining useful monitoring information which are small in data quantity. In energy-limited WMSNs, the research for these information processing techniques would be particularly important. Apart from compression coding and filtering, data fusion also plays an important role, which is mainly shown in saving the resource of network and enhancing the accuracy of collected data. In , for vidThe WMSNs for underground coalmine normally consist of a large number of video, audio and scalar sensor nodes. Given a source of monitoring data, different applications in a network may require disparate information . In addition, some information, such as signals for detecting high concentration of flammable gas, is with top priorities and needs to be reported directly to the ground monitoring center, while other information like air humidity may be queried and processed with normal periods and priorities. Accordingly, it is necessary to deal with these application-specific querying and processing, and to develop distributed filtering and in-network processing architectures, to allow real-time retrieval of useful information . BesidesFor the purpose of gaining useful information which is more accurate and concise, information processing techniques in different level, aiming at different network structure, MB-UWB wireless transmission mode and specific application requirements, should be proposed. By introducing information processing, the overall monitoring performance of coalmine WMSNs will be sufficiently improved.Sensor nodes in underground coalmine WMSNs are large in numbers and restricted in resource, and the environment condition of monitoring regions is generally harsh. If no network management strategy is conducted in the process of network planning, deployment and maintenance, it will be difficult to realize effective monitoring on monitoring regions. The reason is that once the sensor network is deployed, maintaining a network utterly by man seems really hard and even impossible. Electromagnetic interference, different kinds of adverse environment conditions and limited energy of sensors all can be factors that lead to breakdowns or damages in sensor devices, thus making the whole network prone to malfunctions or even crashes. Network management for sensor network aims to realize the following requirements: (1) develop effective management strategies in light of the characteristics of sensor network; (2) monitor various status parameters in real time; and (3) realize self-judgment, self-maintenance and self-determination. Accordingly, by network management, sufficient utilization of network resource can be realized, and we can also provide reliable QoS for applications and satisfy the service requirements of multimedia monitoring in underground coalmine WMSNs. Typical framework for network management in WSNs includes BOSS  and MANNIn , the autHowever, the existing frameworks and protocols for network management in WSNs have not been fully functional, and the research work on network management in WMSNs is still few in number. Thus, in order to guarantee the efficient configuration, operation, administration, and maintenance of underground coalmine WMSNs, efficient frameworks for network management and corresponding protocols should be proposed, combined with specific applications of networks.While we expect smart coalmines to continue to evolve in the future, it is necessary to consider the most robust and reliable technology to facilitate the underground communication in wireless multimedia sensor network. In the sections above, we highlight the superiority of MB-OFDM-UWB in data rate, normalized energy consumption, robustness against fading, immunity to multipath and localization performance, and stress choosing it in underground WMSNs as it performs better than ZigBee and Wi-Fi. It should be stressed, however, that underground mines have many different types of communication such as ground, in-mine, through-the-earth, and disaster communications, and it is difficult to present a single-structure system that can provide solutions to all the applications simultaneously. Except for the research of applying MB-OFDM-UWB into underground coalmine WMSNs, we are still paying our attention to the hybrid schemes which will use multiple short-range wireless transmission techniques. The emerging standard IEEE 802.11ac  has brouAs Cross-layer design is emphasized in Since the systems for coalmine safety monitoring, early warning and disaster relief have urgent demands for wireless video surveillance, wireless voice communication, underground environment monitoring and personnel positioning, this paper presented a framework for constructing a wireless multimedia sensor network for underground coalmines that integrates all these functions. The framework and related discussion filled the gap of absence of efficient and comprehensive structure for designing WMSNs for coalmine.Overall design of WMSNs was presented first, and we discussed in detail the main design challenges, in which MB-OFDM-UWB solution was selected in physical layer. We initially compared the schemes of ZigBee and Wi-Fi with the UWB scheme, and found that UWB can solve both constraints of bandwidth and energy consumption. Then, we further analyzed the several UWB solutions and stress the superiority of MB-OFDM-UWB scheme. The selection of MB-OFDM-UWB wireless transmission solution was based on the characteristics of underground coalmine, and that is different from other schemes for WMSNs which are based on DS-UWB solution. MB-OFDM-UWB transmission solution, together with the characteristics of applications and environments in underground coalmines, was the cornerstone of future research and discussion work. Layer-specific structure was used to discuss the key supporting technologies for underground coalmine WMSNs. Some promising open research areas were also presented, indicating a possible direction for future works.


LIM kinases are common downstream effectors of several signalization pathways and function as a signaling node that controls cytoskeleton dynamics through the phosphorylation of the cofilin family proteins. These last 10 years, several reports indicate that the functions of LIM kinases are more extended than initially described and, specifically, that LIM kinases also control microtubule dynamics, independently of their regulation of actin microfilament. In this review we analyze the data supporting these conclusions and the possible mechanisms that could be involved in the control of microtubules by LIM kinases. The demonstration that LIM kinases also control microtubule dynamics has pointed to new therapeutic opportunities. Consistently, several new LIM kinase inhibitors have been recently developed. We provide a comprehensive comparison of these inhibitors, of their chemical structure, their specificity, their cellular effects as well as their effects in animal models of various diseases including cancer. The LIM kinase protein family is composed of two highly related members, LIM kinase 1 (LIMK1) and LIM kinase 2 (LIMK2). Both have the same unique organization of signaling domains, with two amino-terminal LIM domains, adjacent PDZ and proline/serine (P/S)-rich regions, followed by a kinase domain /cofilin family of actin-binding proteins. Three forms are expressed in mammals: ADF ; cofilin-1, the major ubiquitous form in non-muscle tissues; and cofilin-2, the major form in differentiated muscle. Although these proteins are different, we will use the general term of cofilin, for the sake of simplicity. Binding of cofilin to actin filaments stabilizes a twisted form of F-actin, thereby weakening lateral subunit interactions and promoting filament severing and depolymerization . HoweverBesides LIMK's well-described effect on actin microfilament dynamics through cofilin phosphorylation, several experimental data indicate that LIMK controls microtubule functions, independently of its effect on actin dynamics. Although the mechanism of control of microtubule dynamics by LIMK is still not elucidated, it is now currently admitted that LIMK regulates both components of the cytoskeleton Figure . The folMicrotubule dynamics can be investigated using several methods. First, modification of the appearance of the microtubule network can be an indicator of the microtubule dynamic status: non dynamic or stabilized microtubules are often bundled or with a sinuous, somehow “curly” appearance , 16. MicThe resistance of the microtubule network to cold- or nocodFinally an increased amount of post-translationally modified tubulin forms is a good marker of microtubule stability. Indeed, it has been shown that old and stable microtubules are enriched in detyrosinated and acetylated tubulin . Thus stThe first work reporting that LIMK regulates microtubule dynamics was published by the group of Voyno-Yasenetskaya, in 2005 . Using iin vitro cancer cell proliferation pyrimidines, selected from the same high throughput screening campaign, were also optimized by a group of scientists from Australia. They were found to inhibit LIMK1 in the low micromolar range (compound #7, Table Recently, cell-permeable bis-aryl urea derivatives were discovered and optimized by chemists from the Scripps Research Institute in the US. These compounds inhibit potently LIMK. They appear to be selective for LIMK, but they were only assayed for they inhibitory effect on ROCK and JNK kinases (compound #10, Table Thus, the past 5 years have led to the discovery of several structurally different LIMK inhibitors with different characteristics, which may or may not be suitable, depending on their intended use. For instance, inhibitors designed to be used in cells for the understanding of the function of LIMK have to be both highly specific and cell permeable. The need of specificity is less critical for compounds intended to serve as pharmacological drugs, as multi-target kinases have proven to be more efficient in the treatment of cancer. In that latter case, the knowledge of the compound toxicity when administered to animals is crucial.Located downstream of several signaling pathways LIMK occupies a strategic position. It integrates the upstream signals by regulating the dynamics of actin and, most probably, that of microtubules. Convergent data indicate that, indeed LIMK regulates microtubule dynamics. A molecular dissection of the mechanisms involved in that regulation is however essential to ascertain that control. LIMK is also able to regulate the degradation of the matrix by phosphorylating MT1-MMP and to control the activity of Aurora kinase A.Among the problems still unsolved are the knowledge of the respective role of each of the LIMKs and the understanding of how the activity of each kinase is differentially regulated.The development of optogenetics as well as the controlled genetic ablation of each kinase should help to solve these problems.


Bacteriophages are ubiquitous and numerous parasites of bacteria and play a critical evolutionary role in virtually every ecosystem, yet our understanding of the extent of the diversity and role of phages remains inadequate for many ecological niches, particularly in cases in which the host is unculturable. During the past 15 years, the emergence of the field of viral metagenomics has drastically enhanced our ability to analyse the so-called viral ‘dark matter’ of the biosphere. Here, we review the evolution of viral metagenomic methodologies, as well as providing an overview of some of the most significant applications and findings in this field of research. They exf faeces ,5, of whf faeces , phages f faeces . NumerouGiven their ubiquity in the environment, it is perhaps unsurprising that bacterial evolution is to a large degree driven by phages ,12, faciFor over a century, culture-based methods have been the primary approach to detect and isolate phages . This inThe first culture-independent methods arose in the 1980s as an approach to characterise microbial diversity via DNA sequencing ,31,32. TThe term metagenomics was first coined in 1998  and is dThe growing success of microbial metagenomics, coupled with the increasing awareness of the vital role of viruses in nature, has resulted in attention quickly turning towards the application of metagenomics to the field of virology. The challenges of applying metagenomics to viral samples are many: the lack of universal marker genes, meaning full shotgun metagenomics is required; contamination with bacterial DNA, which is far more abundant than viral, and the consequential difficulties in separating these during sequence analysis ; the vasThe purification of VLPs from an environmental sample is the initial step of any virome project and arguably the most critical. Techniques must strive to produce VLP samples that both qualitatively and quantitatively represent the diversity of the population, thus allowing the linkage of metagenomic observations to the original population . The basBeyond the general approaches, specialised methods catering to particular environments have been developed such as the flocculation, filtration, and resuspension (FFR) method, which uses an iron-based flocculation and subsequent resuspension of virus-containing precipitates and which boasts a 90% recovery rate of marine viral particles ,80.The next step in the preparation of a sample is the extraction and purification of its viral nucleic acid content. This step must yield nucleic acids of sufficient purity and concentration for downstream library construction and sequencing . Before The advent of next generation sequencing (NGS) has resulted in the emergence of rapid, affordable, and high throughput methods such as Illumina MiSeq and Ion Torrent sequencing , making Amplification is commonly one of the final steps in library preparation before sequencing, creating ca. 1000 copies of the DNA to be read by the sequencer . This stImproved library preparation methods have been developed , includiImproved library preparation techniques are still emerging, including the previously mentioned Nextera XT, multiple annealing and looping-based amplification cycles (MALBAC), and NuGEN’s Mondrian microfluidic workstation used in conjunction with the NuGEN Ovation library prep kit. MALBAC reduces amplification bias and increases coverage by utilising a semi-linear amplification method , while tOnce a DNA library has been prepared, sequencing is performed, primarily utilising one of the three main NGS platforms; Illumina (currently the most popular ), Roche Mycobacterium, Enterobacteria, Pseudomonas, and Staphylococcus [While continuing advances in sequencing technology have opened up a multitude of opportunities in the field of viral metagenomics, the enormous amounts of data produced by NGS has also resulted in a major challenge; quality analysis and the processing of sequence data. The primary constraining factor regarding the effective bioinformatic analysis of viromes is the previously discussed absence of universal gene markers in viral genomes, meaning that the detection of viral reads is limited to their alignment against reference viral sequence databases. As of February 2017, the NCBI virus genome database contained just over 2000 phage genomes, with nearly half of those derived from just four genera of bacteria, which have been studied in detail due to their clinical relevancy (lococcus ). It is lococcus . Therefolococcus . Howeverk-mer algorithms may be applied to reduce the time associated with such analyses [K-mers) [The taxonomic composition of a sequenced viral metagenome is often analysed by the alignment of the virome against reference databases using BLAST , or BLAST-based programs such as MG-RAST (MetaGenomic-Rapid Annotation using Subsystem Technology) , MetaPhyanalyses ,89. Thesanalyses  and are [K-mers)  and USEA[K-mers) . However[K-mers)  and are [K-mers)  against [K-mers) . The autIn order to circumvent the large demands for computer processing power of these methods, a number of online resources and tools have become available, making metagenomic analysis more accessible to the uninitiated. These computational pipelines have been designed for the purpose of analysing the composition of metagenomic datasets; in the case of viromes, this means that the abundance and types of viruses present in a sample can be defined. These include virome-specific programs such as VIROME  , MetavirIn addition to these tools, all based upon sequence comparisons to reference databases, numerous similarity-independent methods have arisen in order to circumvent the lack of sequence similarity in current databases . The priThese tools offer just a sample of those available, and the range of bioinformatic tools ready for use in the analysis of viral metagenomes has recently been reviewed ,116. MorBy applying the workflow outlined in Since the pioneering study of Breitbart et al. in 2002 , marine The POV dataset consists of 32 near-quantitative dsDNA viromes collected from samples at various locations, depths, and seasons and has led to many novel insights . To orgaThe POV also provided the first in-depth, large-scale survey of the presence of Auxiliary Metabolic Genes (AMGs) in marine viruses. AMGs are host-derived genes present in phage genomes, and their encoded proteins are suggested to augment the metabolism of infected hosts at key metabolic bottlenecks, facilitating and enhancing the production of new viral particles . SequencA number of other large-scale investigations have been performed , and in The GOV consortia then went further, and sought to link this viral data to microbial hosts. The linking of viral sequence data to host strains has long been a major challenge in the field of viral metagenomics , althougFinally, the prevalence of AMGs in the sequence data was investigated, and 243 putative AMGs were identified, of which only 95 were previously known . These AThe POV and GOV datasets are not definitive representatives of the marine virome due to the limitations and inherent biases of current viral metagenomic techniques and equipment. The above-mentioned studies were dominated by the examination of dsDNA viruses, thus leaving ssDNA viruses underrepresented, an issue which is currently one of the most pressing areas of concern in the field of viral metagenomics ,134. HowHuman metagenome studies have assessed the complex microbial communities associated with the mouth, gastrointestinal tract, lungs, and skin, among other areas. Additionally, human studies have attempted to define correlations between microbial composition and the subject’s age, health status/disease states and lifestyle. Among these, the human gut is undoubtedly the most extensively characterised and was thoroughly reviewed recently . While sPropionibacterium, Staphylococcus, and Corynebacterium were identified in the subjects’ skin in this study, while the viruses recovered through virome analysis of isolated VLPs were dominantly either unclassified or identified as Staphylococcus phages. The presence of high levels of seemingly novel phage sequences in this niche exemplifies the high degree of viral dark matter that is present and highlights that current knowledge on the skin virome represents merely the ‘tip of the iceberg’ of the genetic diversity of phages in the biosphere. The majority of phages recovered from this environment are dsDNA viruses, and this apparent dominance is likely owing to the temperate nature of the majority of these isolates. Most metagenome studies employ Illumina-based sequencing technologies as they produce high sequence coverage, and they are relatively inexpensive. However, the application of PacBio SMRT  sequencing was recently applied to produce ‘finished quality’ genomes of skin metagenome samples and resulted in the identification of a previously uncharacterised Corynebacterium simulans phage–host genome combination [The epidermidis of human skin serves as the primary protective barrier to the external environment and the surface and natural crevices of the skin are host to a variety of microbes. A recent study highlighted that, consistent with other studies, the total metagenome of skin in healthy individuals exhibits temporal stability, while the virome is subject to much greater variability . Bacteribination . To asseVeillonella, Streptococcus, and Megasphaera were identified in this study, and, in addition to the identification of lysogeny-related functions, virulence factors were also abundant, which are asserted to present a reservoir of pathogenic potential/conversion in the human oral environment. It is predicted that the viral communities in the oral cavity are persistent, which is likely a reflection of the stability of host bacterial communities in this environment [It is reported that the human oral cavity is host to six billion bacteria and up to 35 times as many phages . In congironment . FurtherStreptococcus, Burkholderia, Mycobacterium, Enterobacteria, and Pseudomonas were identified [The human lung microbiome has been the focus of several recent studies with implications for understanding and advancing treatment of a variety of pulmonary (and other) diseases. The relationship between the microbiome of the upper and lower respiratory airways is unclear and represents an area of growing interest in the research community. Furthermore, the impact of diseases such as cystic fibrosis (CF) and human immunodeficiency virus (HIV) infection on the lung microbiome has recently received justified research scrutiny ,141,142.entified . Surpris14 bacterial cells [Bifidobacterium sequences were identified in the data relating to 20 of the 173 infants, and (pro)phage sequences largely with Siphoviridae genomic organisation were additionally identified with relatedness to phages of Actinobacteria, Firmicutes, and Gram-negative bacteria. The virome of the human gut is influenced by the health status of the individual, and patients with Crohn’s disease and ulcerative colitis were shown to exhibit ‘abnormal’ viromes, with a much greater level of phages belonging to the Caudovirales family [The microbiota of the human intestinal tract is undeniably one of the most intensely studied microbiomes and is estimated to be constituted by up to 10al cells . Studiesal cells ,148,149,al cells , diet [1al cells ,152, andal cells ,154,155,s family . The virs family ,158. TheOne of the most intriguing findings from the many human gut virome studies was the identification of the so-called ‘crAssphage’ . This phMicrobial metagenomics has long been recognised as possessing the capability to significantly influence industrial biotechnology  from funpol1 genes can be found in 2 Mb of viral metagenomic sequence [Novel enzyme discovery is chief among these applications. Bacteriophages have long been a rich source of enzymes , but thesequence . Aside fsequence . Nonethesequence ,165.The discovery of novel enzymes is not limited to replication-related genes. Bacteriophage lysins are highly evolved enzymes produced by phages which cleave the bacterial cell wall during the final stages of the lytic cycle to facilitate the release of phage particles. Due to their function, attention has turned to these enzymes and their potential use as novel antimicrobials , includiThese examples offer a snapshot of the potential of functional viral metagenomics to serve as a platform to unlock the wealth of useful enzymes that is undoubtedly present in the vast viral sequence space. Indeed, as the annotation of viral sequences continues to improve, the discovery of novel enzymes will increase considerably.The continual improvement of technology and techniques to minimise the introduction of biases and the skewing of produced population structures is the primary challenge facing the field of viral metagenomics. The challenges remain many and varied, but as the methods approach a level of quantitative rigour capable of producing faithful representations of environmental viral communities, viral metagenomics can transition from a tool of observation and description to a means of prediction and application. These advances will also increase confidence in the validity of viral genomes identified purely through metagenomic sequencing, leading to the acceptance of these sequences as bona fide viruses and their inclusion in formal ICTV  viral taxonomy, a process about which discussion has already begun . The ide


Recently, self-healing technologies have emerged as a promising approach to extend the service life of social infrastructure in the field of concrete construction. However, current evaluations of the self-healing technologies developed for cementitious materials are mostly limited to lab-scale experiments to inspect changes in surface crack width  and permeability. Furthermore, there is a universal lack of unified test methods to assess the effectiveness of self-healing technologies. Particularly, with respect to the self-healing of concrete applied in actual construction, nondestructive test methods are required to avoid interrupting the use of the structures under evaluation. This paper presents a review of all existing research on the principles of ultrasonic test methods and case studies pertaining to self-healing concrete. The main objective of the study is to examine the applicability and limitation of various ultrasonic test methods in assessing the self-healing performance. Finally, future directions on the development of reliable assessment methods for self-healing cementitious materials are suggested. Concrete is one of the most resilient construction materials in the world. However, cracks in concrete due to various reasons may result in serious durability and serviceability problems. Repair and maintenance costs have continuously increased in recent years, and thus, many researchers have tried to develop crack control and self-healing technologies ,6,7,8,9.To satisfy this need for self-healing concrete, researchers have concentrated on the development of engineered self-healing technologies using organic or inorganic chemical agents ,11,12, mWith the ongoing development of self-healing technologies for concrete, there is a growing need to develop methods that are able to accurately evaluate the effectiveness of these technologies ,27,28,29However, current evaluations of the self-healing technologies developed for cementitious materials are mostly limited to lab-scale experiments for inspecting changes in surface crack width  and permeability. Furthermore, there are no unified test methods established for assessing the efficiency of self-healing. With respect to the application of self-healing concrete in actual construction, nondestructive test methods are required such that evaluation tasks do not interrupt the use of structures ,50.Over the last decade, self-healing performance has been assessed by various ultrasonic nondestructive test methods , which iGiven the above-mentioned concerns, the main objective of this study is to examine the applicability and limitation of various ultrasonic test methods in assessing the effectiveness of self-healing technologies developed for cementitious materials. This is performed by thoroughly reviewing the principles of ultrasonic test methods and case studies related to the application of these methods on self-healing concrete. The applicability and limitation of the ultrasonic test methods are analyzed based on the following five criteria: Evaluation of crack size, evaluation of regained mechanical properties , evaluation of regained durability properties , appropriate self-healing agents and assessment of in situ structures. Finally, future directions on the research and development of reliable assessment methods for self-healing cementitious materials are proposed.The UPV method is widely used to detect internal defects, and estimate crack depth and compressive strength for concrete structures. Therefore, standard test methods for UPV measurements are well established and are specified in ACI 228.2R  and ASTMFerrera et al.  evaluateZhong and Yao  evaluateTime-of-flight diffraction (TOFD) methods have been used to estimate the recovery of crack depth. This provided evaluations of self-healing performance in cementitious materials with various self-healing mechanisms through microcapsules and impregnation and encapsulation of lightweight aggregates ,15,30.Most of the energy generated by surface impact is transmitted through Rayleigh surface waves instead of body waves . AlthougAldea et al.  presenteAggelis and Shiotani  evaluateThe characteristics  of ultrasound propagation are generally dependent on not only the frequency components of propagated waves but also the properties of materials. Ultrasound propagates through concrete without displaying scattering effects at frequencies less than 50 kHz and displaying scattering at frequencies exceeding 100 kHz . TransmiIn et al.  monitoreA coda wave indicates reverberation components of randomly scattered waves due to scattering effects in heterogeneous media . The length of the scattered wave travel path exceeds that of the direct wave path and thus, the arrival time of scattering wave components (coda wave) is after that of direct wave components  . As showHere, Liu et al.  conducteThe deformation or failure of solid media leads to the detection of generated sound (elastic wave) through AE sensors . The genIn the previous studies, Granger et al. ,40 monitIn previous studies, various self-healing assessment methods have been classified based on objectives and characteristics ,8,9. InfIn previous reviews, Van Tittelboom and De Belie  analyzedIn this study, for the discussion of applicability and limitations, in-situ applicability is adopted as a criterion and four additional criteria are defined as follows: evaluation of the change in crack size, evaluation of regained durability properties, evaluation of regained mechanical properties and appropriate self-healing agents. First, self-healing was evaluated and verified through the most intuitive criteria, namely microscopic observation to monitor changes in crack width at the surface. Furthermore, the maximum self-healing performance of each self-healing agent was defined as the ratio of the initial crack width at the surface to that of the fully closed crack. However, it was not possible to measure a crack width in a specific location since crack width is not constant along a crack. Therefore, the change in crack size could also be considered as crack depth. Second, the ultimate goal to develop self-healing technology for concrete structures is to improve the durability properties. It is not possible to apply current lab-scale durability evaluation methods, such as permeability and chloride-ion diffusivity tests, on concrete structures in operation. Therefore, it is necessary to suggest appropriate nondestructive techniques to evaluate durability properties in various fields. Third, existing research focused on regained mechanical properties, although the efficiency of recovery of mechanical properties is considerably lower than the performance of regained durability properties and crack sizes. Fourth, various self-healing materials possess different mechanisms to seal cracks. Therefore, it is necessary to consider different self-healing mechanisms, effectiveness of fit between techniques, and self-healing agents. Fifth, the ultimate goal of studying nondestructive tests as assessment techniques for self-healing concrete is to provide effective evaluations and maintenances without any interruption in the structures. Finally, the limitation of each nondestructive technique for evaluating self-healing concrete is discussed. In this classification, criteria are evaluated with respect to four grades, studied in previous literature, must be able to apply, might be able to apply and might not be able to apply.One of the most widely studied parameters for the evaluation of self-healing performance is crack width, which is typically measured via microscopic observations. In recent years, image scanning-based techniques have emerged as a potentially efficient approach for the measurement of surface crack width. The estimated results of crack width by image scanning are quite similar to those by microscopic measurements. Therefore, it may not be meaningful to develop another method for crack width estimation using ultrasonic techniques. The present review focuses on the other crack size indices, including crack depth, with the summarized results shown in The change in the global volume of cracks could be one of the most suitable indices for the evaluation of self-healing performance. However, there are no reliable ultrasonic test methods capable of estimating the global crack volume to date. Therefore, discussions for the change in global crack volume due to self-healing are excluded from the scope of this paper.First, the review focuses on the recovery of crack depth ,15,30 usd cracks . The fasSecond, it is important to study surface-wave application to estimate the recovery of crack depth, despite the lack of existing research on this topic. This is the result of crack-depth estimation methods using surface-wave transmission having considerably more sensitive characteristics when compared to pulse velocity. As mentioned in Third, the crack depth may be estimated by locating the crack tip through the localization of AE in which the distance to the crack tip from each sensor is determined using different arrival times at multiple sensors as mentioned in Fourth, the evaluation of crack depth using diffusion phenomena of ultrasound in concrete is examined, although the history of nondestructive techniques using diffuse ultrasound in concrete is not intensively studied when compared with pulse velocity and surface-wave transmission ,68,69,70Finally, crack depth estimation using CWI is not intensively studied as compared to that using pulse velocity, surface wave, and diffuse ultrasound. Therefore, the possibility of applying CWI techniques to self-healing concrete should be carefully considered. The measured coda wave signal scattered in concrete internal structures will change due to the self-healing process ,29. AddiThe nondestructive evaluation of the durability properties of in-situ concrete structures was rarely required until recent years, and thus few previous studies tried to investigate relationships between the durability properties and NDT parameters. However, it is necessary to perform research to evaluate the increase in durability regained in the process of self-healing with the development of self-healing technologies. Most previous studies have evaluated regained durability properties including water permeability ,25,26,32In addition, research on the estimation of durability properties via ultrasonic nondestructive test methods has only examined the correlation between gas permeability and pulse velocity. First, the correlation model between ultrasonic parameters and gas permeability of cementitious materials was investigated . In theiThe regain in the durability properties due to self-healing may be evaluated by examining the microstructural characteristics of concrete. Various ultrasonic techniques have been attempted to characterize the microstructure of concrete ,73,74,75However, as indicated in A few studies have focused on the regained mechanical properties in the process of self-healing to evaluate the performance of developing agents ,44,45,46In general, concrete has unique characteristics that show a strong correlation between strength and stiffness. Thus, many concrete design codes worldwide  specify the relationship between the strength and stiffness of concrete. Accordingly, regain in concrete strength in previous NDT studies was predicted using the estimation of the regain in stiffness. However, the development of strength recovery due to self-healing was frequently found to be relatively small, except for certain capsule-based self-healing ,39. TherRegained mechanical properties were evaluated using AE analysis with respect to flexural strength, stiffness and AE parameters in self-healing concrete ,44,45,46The relationship between mechanical properties and pulse velocity was investigated. First, UPV is the most widely used nondestructive technique to evaluate mechanical properties through standard code. Generally, compressive strength is directly related to stiffness, which is related to tightness. These relationships aided in deriving a strength prediction model using pulse velocity based on the estimation of stiffness and tightness. An increase in the compressive strength at an early age in the process of curing was monitored through R-wave velocities ,79. The In contrast, the application of regained mechanical properties in the process of self-healing as well as the monitoring of the development of concrete strength using diffuse ultrasound phenomena are not examined to date. A study could first monitor the development of compressive strength and stiffness of concrete at an early age. This could be followed by applying diffuse ultrasound and CWI to evaluate the regained mechanical properties in the process of self-healing.The evaluation indices, occurrence of crack damage, effects of environmental conditions and standard criteria should be reviewed as shown in Several types of evaluation indices are used in each technique. In the case of UPV and CWI, an evaluation index is dependent on the other evaluation indices . Therefore, only one measured index is used for evaluation of maintenance and inspection of damage in concrete structures. In contrast, specific evaluation indices are independent on the other parameters in surface-wave transmission, AE, and diffuse ultrasound. Therefore, in the case of surface-wave transmission, AE and diffuse ultrasound, the most sensitive index is determined first to establish standard test methods toward future practical application on the real structures.The effect of various environmental conditions also constitutes an important issue in the application of in-situ structures. Therefore, the authors classify the environmental effects into three states: major, moderate and minor. The measurements of pulse velocity are dependent on the moisture conditions and water content. The change in R-wave velocities is very low when compared to P-wave velocities due to the change in moisture conditions. The current study concludes that the transmission of surface wave corresponds to minor effects with respect to the environmental conditions. Conversely, an analysis of the AE signals is dependent on environmental noises. Therefore, the determination of threshold to neglect the environmental noise signals is an important factor. For example, in a lab-scale evaluation, the sounds from the universal test machines are also measured in the software and should be recognized as noises. The diffusion of ultrasound in concrete is also affected by the changes in environmental conditions, such as the influence of temperature and coupling condition between transducers to surface. However, the relative velocity change in ordinary temperature is lower than 1%. Effects from the moisture conditions and water contents in concrete are not clearly investigated to date.In summary, UPV and AE sounds were applied on in-situ structures to detect damage and they have been tried to evaluate self-healing performance in large-scale concrete beam . The posThe measurements of pulse velocity, transmission coefficients, diffusion parameters and characteristics of coda wave can be applied in all types of self-healing agents. The nondestructive evaluated performance through each self-healing agent is listed in First, UPV is applied to evaluate self-healing performance using autogenic self-healing, chemical agents, bacteria, microcapsules, and macrocapsules ,22,30,48Second, transmission coefficients are used to evaluate an autogenic self-healing process . AlthougDiffuse ultrasound and CWI techniques are affected by the internal microstructure of concrete. Therefore, measured signals can change from the process of crack filling using various self-healing materials in identical concrete compositions. From this viewpoint, the development of comprehensive evaluations on the performance of self-healing between various agents is desired. Although diffusion and dissipation indices can experience slight changes due to the types and contents of self-healing agents, it may be concluded that the effects of substituting self-healing agents such as bacteria are negligible for some parts of cement pastes and aggregates, when compared with the effects of changes in mix proportions.Finally, AE analysis is not appropriate for general self-healing mechanisms due to the occurrence of low slight acoustic signals from the crack-filling materials when compared to crack propagation. AE-based evaluation for self-healing concrete is suitable for comparison studies in the process of improving the performance of capsule-based self-healing element technology or the technologies that can make recovery of mechanical properties.Finally, the limitations of each nondestructive technique for the evaluation on self-healing concrete are discussed in When surface-wave transmission is used as a nondestructive evaluation method, assessment is based on the characteristics of Rayleigh waves that transfer cracks with lengths lower than the wavelength and reflect cracks that are longer than the wavelength. In order to evaluate crack properties through surface-wave transmission, it is necessary for the specimen height to exceed the wavelength of impact sources to recognize the specimen as a half-infinite solid media. Therefore, specimen size is considerably large for lab-scale evaluations when the side and bottom reflections of propagated waves are considered. Additionally, improved surface-wave transmission measurement techniques applying non-contact air-coupled sensors were studied to avoid a coupling problem between the concrete surface and contact accelerometers ,65. CurrAs shown in Currently, excitations through transducers with wide and high frequency ranges are typically used to simulate the diffusion phenomena of ultrasound in concrete based on scattering effects between matrices and aggregates. Concrete is a relatively heavy loss material from the viewpoint of attenuation of waves among construction building materials. Thus, it is necessary to insert an amplified signal into transducers to measure output signals with reasonable amplitude. Furthermore, there are several diffusion parameters including dissipation, diffusivity and ATME. It is necessary to determine the indices that are appropriate for evaluating different damage conditions and recovery of cracks, pores or durability. In addition, variability of measured diffusivity is large, although diffusivity exhibits the most ideal behavior to monitor internal changes and self-healing results.CWI techniques are also based on diffusion phenomena. However, the variability of coda wave parameters is considerably small when compared to diffusivity. Relative velocity change and stretching parameters are used as indices of CWI techniques. The analyzed time ranges differ across studies. The differences from the analyzed time domain do not significantly affect the results of stretching parameters. However, the standardization of the analyzed region is necessary to improve the reliability of the test results.The results of analysis of the applicability and limitation of nondestructive assessment techniques have suggested that the development of correlation model between self-healing indices  and nondestructive test parameters  should be initially examined, followed by performing a verification of the mock-up structures.First, the evaluation of change in crack size focusing on crack depth is discussed in Second, existing research did not reflect the ultimate goal of developing self-healing concrete. Previous studies that focused on self-healing element technologies involved a limited and concentrated target performance of crack filling. It is not possible to expect that all material properties were regained to levels prior to the occurrence of damage. Therefore, self-healing efficiency defined by regained durability properties should be studied. In the previous studies, the water permeability in concrete was significantly influenced by the initial crack width, roughness of crack, and microstructure . The roughness of crack surface may affect the self-healing process to form crack-filling materials between water and cement paste . In addiThird, nondestructive techniques using UPV and AE are the preferred technologies to evaluate mechanical properties. The present study recommends that AE for flexural loads is first determined before determining pulse velocity to evaluate the stiffness recovery. In contrast, there remains uncertainty as to whether the other techniques  might be used to evaluate mechanical properties. This is the result of a lack of existing research examining the same in conjunction with a direct correlation between strength (or stiffness) development and the nondestructive characteristics of each technique.(1)The measurement of UPV and its transmission time is one of the most developed ultrasonic test methods and is widely used to evaluate the performance of the self-healing technologies. However, the partial closing of cracks and moisture conditions in concrete structures can affect the evaluation results of the self-healing performance by the UPV method. In addition, the velocity-based approach is sensitive to moisture conditions.(2)With respect to the other nondestructive test methods , there are no standard test procedures to measure, process and analyze the test data. Thus, it is necessary to determine appropriate self-healing evaluation procedures for each test method by considering the target of self-healing performance evaluation .(3)The diffuse ultrasound and CWI methods are based on the scattering of elastic waves between aggregates and matrices. Therefore, these techniques are suitable to assess the self-healing of internal damages in concrete that are associated with durability properties.(4)Nondestructive evaluations of mechanical properties  are studied through measurements of either P-wave or R-wave velocity. Some researchers observed stiffness recovery in the process of self-healing. However, the range of regained strength is quite small, which raises the question as to whether it can be used as a measure for the performance of self-healing technologies. Therefore, when evaluation methods for the regain of mechanical properties are studied, it is proposed to focus on the stiffness using UPV or AE.(5)All ultrasonic test methods with the exception of AE analysis can be applied for all types of self-healing materials ranging from chemical agents to capsule-based mechanisms. In contrast, the AE analysis can only be applied to regain mechanical properties from capsule-based self-healing materials because the technique is based on sensing the sounds of capsule breakages. Capsules are broken in the initial fracture test and the leakage of healing agents is assumed in the detected locations.In this study, theories and case studies of five ultrasonic-based nondestructive test methods  were thoroughly examined with respect to their applicability and limitations in assessing the effectiveness and performance of the self-healing technologies developed for cementitious materials. The findings and conclusions of this study can be summarized as follows:


The concept of growing plants for human health and general well-being, rather than for consumption as food alone, is changing people’s perception of plant biotechnology and synthetic biology. Resurrecting the long-forgotten connection between plants and health has launched a new generation of botanical therapeutics, which include dietary supplements, functional foods, pharmaceuticals and multi-component drug mixtures. Technological and methodological advances have made the discovery, validation and manufacture of high-value phytochemicals a reality, and botanical therapeutics have come of age.Plants are integral to human well-being. In addition to their obvious nutritional value, for centuries they have also been used for their healing properties. Plant parts, potions and powders have been, and continue to be, used in traditional medicine by a number of tribes with varying degrees of success to boost vigor, as well as to prevent and cure disease. Archaeological evidence suggests the use of plants by humans for medicinal purposes during the Paleolithic age, with the first written evidence dating back to the Sumerians .By the 21st century, the pharmaceutical industry had mostly replaced natural plant extracts with chemically synthesized molecules to prevent and treat diseases. With the introduction of medicine in the form of easy to consume ‘pills’, it is easy to dissociate plants from health and thus overlook the many modern medicines which still contain phytochemicals in their natural form or as derivatives. Until the 20th century plant extracts were regularly screened for novel pharmaceutically active compounds, which were then purified from the native plants. The emphasis of the pharmaceutical industry then shifted to making these natural products synthetically, and using them as templates for generating structural analogues as a means of obtaining new chemical entities with desired efficacy.The richness and diversity of novel drugs that can be discovered from plants have also been challenged by competition from the fields of combinatorial chemistry . All livIn addition to the pharmacological relevance of plant natural products, there is a growing trend of boosting human well-ness by incorporating plant parts and products into daily diets in the form of functional foods and dietary supplements (Box 1). The regular consumption of certain fruits and vegetables is suggested to reduce the risk of chronic diseases like cancer, diabetes, heart diseases and obesity by functioning as medicinal nutrition therapy  and Amyris (amyris.com) take pride in using synthetic biology strategies for solving the supply-chain issue of nature through the bulk production of plant natural compounds in microbial organisms. There is an upsurge in biotech startup companies like Ginkgo Bioworks (ginkgobioworks.com) that are based on engineering microbes for customers across multiple markets. Through its foundries, this organism-engineering company has scaled and automated the process of making all sorts of chemicals in microorganisms. These companies primarily focus on metabolically engineering organisms to make profitable amounts of high-demand compounds that find applications in nutrition, health and personal care products, flavors and fragrances, and cosmetic additives. Besides trait engineering in plants with a view to augmenting human health, the production of high-value phytochemicals using synthetic biology approaches is a reality today. Companies like Evolva . High-throughput sequencing technologies will generate a torrent of data in the coming decade from several ongoing multi-species plant projects. The affordability and ever-increasing sensitivity of these techniques has rendered sequencing of non-model, difficult to cultivate, and slow-growing plants plausible. Indexing species-specific phytochemical signatures will enable effective rational bioprospecting in the future. Alongside good cataloging of phytochemicals, it is also time to expand engineering toolkits for both plant biotechnology and synthetic biology to include less obvious molecular targets. For instance, the engineering of exporters in microorganisms would obviously facilitate the export of the product out of the cell, but in addition could also circumvent feedback inhibition and compound-associated toxicity, which in turn can increase yields and enable cost-effective downstream purification of the product.A big challenge still for phytochemical-based therapeutics is integrating the discovery of complex biosynthetic pathways with better characterization of molecular targets for the prevention and treatment of complex diseases. Likewise, assessing the compatibility of multifunctional phytochemicals and complex multicomponent plant extracts for disease-specific treatment is a challenge. However, contemplating the use of natural products in functional medicinal foods as a means of disease prevention, rather than treatment, is highly conceivable. As holistic approaches to prevention and treatment of sickness are increasingly gaining popularity, convincing the consumer market to make food choices for health benefits might be easier than currently anticipated. Plants easily represent the most abundant renewable source of high-value compounds, as they have evolved to synthesize a range of complex natural products efficiently. In addition, the upsurge in energy and chemical raw material costs, together with environmental concerns of carbon dioxide emission are detrimental to the pharmaceutical manufacturing of plant compounds. The result of dramatic advances in metabolic engineering, synthetic biology, genomics, proteomics, functional and molecular characterization, and pharmaceutical or nutraceutical screening, sets the path forward for botanical therapeutics. In the future, farmers who adapt their farming practices for the production of crops that promote health rather than provide calories are predicted to profit, and as a result the planet could become greener and healthier.


Over time plants developed complex mechanisms in order to adapt themselves to the environment. Plant innate immunity is one of the most important mechanisms for the environmental adaptation. A myriad of secondary metabolites with nutraceutical features are produced by the plant immune system in order to get adaptation to new environments that provoke stress (stressors). Hormesis is a phenomenon by which a stressor  stimulates the cellular stress response, including secondary metabolites production, in order to help organisms to establish adaptive responses. Hormetins of biotic origin , in certain doses might enhance plant performance, however, in excessive doses they are commonly deleterious. Biostimulants or biological control compounds of biotic origin are called “elicitors” that have widely been studied as inducers of plant tolerance to biotic and abiotic stresses. The plant response toward elicitors is reminiscent of hormetic responses toward toxins in several organisms. Thus, controlled management of hormetic responses in plants using these types of compounds is expected to be an important tool to increase nutraceutical quality of plant food and trying to minimize negative effects on yields. The aim of this review is to analyze the potential for agriculture that the use of biostimulants and biological control compounds of biotic origin could have in the management of the plant hormesis. The use of homolog DNA as biostimulant or biological control compound in crop production is also discussed. Currently, there are generalizable processes from which different terminologies have been constructed, including those from which they may be described; hormesis is a process of this type, present in all organisms . In toxiArabidopsis thaliana at low doses of a synthetic elicitor 2-(5-bromo-2-hydroxy-phenyl)-thiazolidine-4-carboxylic acid (BHTC) enhanced root growth, while high doses of this compound inhibited root growth, besides inducing defense , and various performance endpoints such as cognitive functions, immune responses, among others . ReportsGenerally, cellular and molecular mechanisms under the effect of hormesis include the activation of the growth factor signaling pathways, ion channels, kinases and deacetylases, and transcription factors responsible for the production of cytoprotective proteins such as chaperones , antioxidant enzymes , and growth factors , as well as cell survival genes . In planM. truncatula seedlings with pathogenic or symbiotic bacteria induces the oxidative burst in the host, with a major difference in the levels of ROS production  by X. campestris pv. vesicatoria (avrBsT) infection. Strong induction of defense- and cell death-related genes in transient CaHSP70a overexpression was also observed /Akt pathway, p53 activation, and the HSPs, adaptations are also mediated by Hpression . Environpression . HSPs repression . Heat stobserved . Howeverobserved .Hormetins according to Figure 1). The developments of analysis of the hormetic dose responses in plants need rigorous criteria in homogeneous selection of the individuals, several doses of the biostimulant or biological control compound, exposure time, and greater sample sizes , a polyphenol possessing several biological activities, prevent early mortality and help in general health in mammalians Avoiding the activation of the defense metabolism until harvest, in order to avoid the defensive reaction of the plant during its development.(2)Focusing the defensive metabolism effort only in the edible part of the plant and thereby reducing the production of secondary metabolites in non-edible parts.(3)Differential induction of specific metabolic pathways for the synthesis of nutraceuticals testing with different doses and types of elicitors.(4)Management of increased elicitors’ doses throughout the phenological stages during plant cultivation. Low doses during vegetative stage, and high doses during fruit development.Although there has been progress in the characterization of hormetic curves with the application of abiotic stressors, there is still an area of opportunity related to study of biotic elicitors. The above would confer advantages to the strategy presented here because it should influence the absence of negative effects on the environment and, consequently, on health. Some authors have previously recognized the use of biotic elicitors such as a tool to implement sustainable agriculture . The useBased on the abovementioned, there is evidence to suggest that biostimulants and biological control compounds of biotic origin (elicitors) can induce the phenomena of hormesis in plants. Hormesis management by mild stress (eustress) might be a powerful tool in improvement of food nutraceutical quality in crops. In this context, adaptive responses induced by cross talking of stress signals between species  can be a powerful tool in improvement of human health.MV-H was responsible for reviewing of literature and writing the paper. IT-P was responsible for the work team and the conception of the research topic. RG-G the conception of the research topic and reviewing of the literature. IM-B, LA-A, RO-V, ER-G, and SR-G were in charge of reviewing the writing.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Non-alcoholic fatty liver disease (NAFLD) is a spectrum of diseases ranging from simple steatosis without inflammation or fibrosis to nonalcoholic steatohepatitis (NASH). Despite the strong association between dietary factors and NAFLD, no dietary animal model of NAFLD fully recapitulates the complex metabolic and histological phenotype of the disease, although recent models show promise. Although animal models have significantly contributed to our understanding of human diseases, they have been less successful in accurate translation to predict effective treatment strategies. We discuss strategies to overcome this challenge, in particular the adoption of big data approaches combining clinical phenotype, genomic heterogeneity, transcriptomics, and metabolomics changes to identify the ideal NAFLD animal model for a given scientific question or to test a given drug. We conclude by noting that novel big data approaches may help to bridge the translational gap for selecting dietary models of NAFLD. Non-alcoholic fatty liver disease (NAFLD) affects between 25% to 30% of the general population and is an emerging non-communicable health epidemic . NAFLD eThe abundance of food, particularly high in fat, the increase in portion sizes, and consumption of beverages sweetened with sucrose or high-fructose corn syrup are all dietary factors that have been incriminated for the current rise in the incidence of obesity and the metabolic syndrome . FeatureDespite the strong association between dietary factors and NAFLD, translational research in the field of NAFLD has been limited by the multitude of dietary models and the complex phenotype of the disease, both metabolically and in the liver. In addition, the relevance of individual animal models of the disease to the human phenotype has been questioned, both in the field of NAFLD and in other diseases ,12. One An influential hypothesis encompassing the pathogenesis of NASH was first encompassed by Day and colleagues as the “two-hit hypothesis”, where a first hit, steatosis, was followed by an additional insult, for example oxidative stress, for the development of steatohepatitis . NeverthIncreasing recognition of the disease and additional efforts to elucidate its pathogenesis have led to an increase in animal models of NAFLD over the past years ,20. ReceThe association between NAFLD and obesity led to the development of an HFD that matches modern Western diets. The first described high-fat diet, tested in male Sprague–Dawley rats by Lieber et al.  demonstrated the development of steatosis within three weeks associated with insulin resistance and increased markers of fibrogenesis . Subsequdb/db or ob/ob mice to better replicate the human metabolic and hepatic profile seen in NAFLD.The MCD is one of the most popular dietary models of NASH. This lipogenic diet is generally rich in sucrose and fat  but is deficient in methionine and choline. Methionine and choline are essential for hepatic β oxidation and the production of very low-density lipoproteins (VLDL), and their deficiency leads to extensive hepatic inflammation as early as two weeks of feeding, as well as significant fibrosis after six weeks . AlthougHigh-cholesterol diet is an important risk factor for the progression of hepatic inflammation in NAFLD both in animal models and in humans ,27. NeveFructose consumption has been linked to obesity, dyslipidemia, and insulin resistance, and growing evidence suggests that fructose contributes to the development and severity of NAFLD . IncreasA ketogenic diet has been shown to induce hepatic steatosis in rodents, although this is controversial in humans due to variations in macronutrients composition . A ketog4-CDAA arm) at nine months of diet [The choline-deficient L-amino-defined (CDAA) diet is similar to the choline-deficient diet, but replaces proteins with a mixture of L-amino acids. C57BL/6 mice fed a CDAA diet developed liver injury that mimicked NASH features while inducing peripheral insulin resistance . In addi of diet . However of diet ,42.Conjugated linoleic acid (CLA) refers to a mixture of positional and geometric isomers of linoleic acid. Sources of CLA include dairy products and meat from ruminant animals or those contained in synthetic products . Althougdb/db mice, homozygous for a mutation in the leptin receptor leading to defective leptin signaling, ob/ob mice with autosomal recessive mutation in the leptin gene leading to mice that are grossly overweight, hyperphagic, hyperinsulinemic, hyperglycemic, and resistant to insulin. Ob/ob mice develop spontaneous liver steatosis but do not develop NASH unless secondary triggers are added [db/db mice, ob/ob mice are resistant to fibrosis, as leptin is an essential mediator of hepatic fibrosis [Numerous other models of NAFLD have been described. Genetic models of NAFLD include re added . Interesfibrosis .A number of non-rodent animal models of NAFLD have also been reported. For example, dietary manipulation of the Ossabaw pig led to the development of the metabolic syndrome and features of NASH in this animal , while fThe ideal animal model of NASH/NAFLD would encompass the metabolic features of the human disease, including obesity, dyslipidemia, insulin resistance, as well as replicate the liver histological findings found in patients. Unfortunately, the perfect human NASH model has not yet been identified or developed, although such a mouse model of NASH would greatly facilitate and encourage drug and biomarker discovery in the field . Below, In the framework of preclinical studies for therapeutic discovery, the value of animal models in general has been somewhat controversial . AlthougOne strategy to overcome this translational challenge is to adopt a multiscale setting including big data approaches combining clinical phenotype, genomic heterogeneity, transcriptomics, and metabolomics changes to identify the ideal NAFLD animal model for a given scientific question or to test a given drug. Unfortunately, the theoretical framework and robust cross-species technologies for this task are currently lacking; therefore, authors have preferred to rely on transcriptomics, or the systematic and global assessment of RNA expression in a given tissue as a reasonable proxy for such approaches. For example, the transcriptomic assessment of liver tissue in “severe” NAFLD fibrosis with advanced fibrosis compared to “mild” NAFLD with low levels of fibrosis found that metabolic and regenerative pathways were deregulated in severe NAFLD, and revealed an overlap among the gene expression patterns of severe NAFLD, cardiovascular disease, and cancer . InteresNAFLD is a complex disease with an increasing epidemiology. Currently, no specific therapeutic alternative has been developed, partly due to the lack of robust reproducible dietary animal models of the disease. Novel big data approaches may help to bridge the translational gap for selecting dietary models of the disease for specific research questions or for testing specific drugs. It is likely that, in line with the worrying epidemiological expansion of the disease and rising interest from the industry, translational efforts aiming to address these issues will further develop in the future.