Recent Submissions

  • Soliton-based single-point pulse wave velocity model: A quantum mechanical approach

    Piliouras, Evangelos; Laleg-Kirati, Taous-Meriem (Biomedical Signal Processing and Control, Elsevier BV, 2021-10-20) [Article]
    Cardiovascular diseases (CVDs) are one of the strongest contributors to mortality rates worldwide. To assess the severity of a clinical situation, various indices of CVD risk have been established, one of them being the arterial stiffness. Arterial stiffness is the quantification of the arterial elasticity. There exist several methodologies to assess the level of arterial stiffness where their non-invasiveness is a matter of great importance. The pulse wave velocity (PWV) is used as an indicator of the arterial stiffness and satisfies the non-invasiveness requirement. Specifically, the carotid-femoral PWV-based method is considered one of the most trustworthy methodology in quantifying the arterial stiffness. This paper proposes a new model for the PWV along with insights on a real scenario implementation. The model utilizes Semi-classical signal analysis (SCSA) as the main signal processing framework to analyze the blood pressure waveform. The proposed model is suggested to be used as an add-on to existing methodologies, bringing the feature of single-point measurement, once a calibration phase has preceded. The use of such a model can eliminate the pulse propagation time-delay, one of the dominant sources of PWV error. Additionally, the single-point measurement paves the way of prolonged PWV monitoring that can reveal new clinical features of the PWV. The model was validated both in a theoretical and data basis, validating its predicted hyperbolic PWV behavior with respect to the SCSA parameters.
  • NERO: a biomedical named-entity (recognition) ontology with a large, annotated corpus reveals meaningful associations through text embedding

    Wang, Kanix; Stevens, Robert; Alachram, Halima; Li, Yu; Soldatova, Larisa; King, Ross; Ananiadou, Sophia; Schoene, Annika M.; Li, Maolin; Christopoulou, Fenia; Ambite, José Luis; Matthew, Joel; Garg, Sahil; Hermjakob, Ulf; Marcu, Daniel; Sheng, Emily; Beißbarth, Tim; Wingender, Edgar; Galstyan, Aram; Gao, Xin; Chambers, Brendan; Pan, Weidi; Khomtchouk, Bohdan B.; Evans, James A.; Rzhetsky, Andrey (npj Systems Biology and Applications, Springer Science and Business Media LLC, 2021-10-20) [Article]
    Machine reading (MR) is essential for unlocking valuable knowledge contained in millions of existing biomedical documents. Over the last two decades1,2, the most dramatic advances in MR have followed in the wake of critical corpus development3. Large, well-annotated corpora have been associated with punctuated advances in MR methodology and automated knowledge extraction systems in the same way that ImageNet4 was fundamental for developing machine vision techniques. This study contributes six components to an advanced, named entity analysis tool for biomedicine: (a) a new, Named Entity Recognition Ontology (NERO) developed specifically for describing textual entities in biomedical texts, which accounts for diverse levels of ambiguity, bridging the scientific sublanguages of molecular biology, genetics, biochemistry, and medicine; (b) detailed guidelines for human experts annotating hundreds of named entity classes; (c) pictographs for all named entities, to simplify the burden of annotation for curators; (d) an original, annotated corpus comprising 35,865 sentences, which encapsulate 190,679 named entities and 43,438 events connecting two or more entities; (e) validated, off-the-shelf, named entity recognition (NER) automated extraction, and; (f) embedding models that demonstrate the promise of biomedical associations embedded within this corpus.
  • Cell-to-Cell Communication During Plant-Pathogen Interaction

    Tabassum, Naheed; Blilou, Ikram (Molecular Plant-Microbe Interactions®, Scientific Societies, 2021-10-19) [Article]
    Recognition of pathogen activates cellular signaling such as ROS, MAPK, Ca2+ signaling which ultimately fine-tunes the cell to cell communication. These further coordinates with the hormone signaling to execute the defense response at local and systemic level. Interestingly, phytopathogens have also evolved to manipulate the cellular and hormonal signaling and/or exploit hosts cell to cell connection in multiple ways at multiple levels. Overall, the triumph over the pathogen depends on prime decisions and actions-how the plant maintain, regulate and eventually break the intercellular communication through apoplastic and symplastic routes. Here, we review how intercellular communication in plants is mediated, manipulated and maneuvered during plant-pathogen interaction. Key words: Cell to cell communication, plant defense, plasmodesmata, phytohormones
  • Detailed investigation of the mixing field and stability of natural gas and propane in highly turbulent planar flames

    Elbaz, Ayman M.; Mansour, Mohy S.; Akoush, Bassem M.; Juddoo, Mrinal; Khedr, Alaa M.; Al-Bulqini, Hazem M.; Zayed, Mohamed F.; Ahmed, Mahmoud M.A.; Roberts, William L.; Masri, Assaad R. (Fuel, Elsevier BV, 2021-10-18) [Article]
    In most practical combustion devices, the actual combustion process occurs within different mixture inhomogeneity levels. Investigating the mixture fraction field upstream of the reaction zones of these flames is an essential step toward understanding their structure, stability, and emission formation. In this study, the mixture fraction fields were measured for turbulent non-reacting inhomogeneous mixtures immediately downstream from the slot burner exit, using Rayleigh scattering imaging. The slot burner had two concentric slots. The inner air slot can be recessed at distances upstream from the exit of the outer fuel slot, allowing various degrees of mixture inhomogeneity. Mixture fraction field statistics and the two-dimensional gradient were utilized to characterize the impact of the air-to-fuel velocity ratio, global equivalence ratio, fuel composition, Reynolds number, and the premixing length on the mixture mixing field, and thus flame stability. These impacts were evaluated by tracking the normalized mean mixture fraction and mixture fraction fluctuation transition across the regime diagram for partially premixed flames. The results showed that the air-to-fuel velocity ratio was the critical parameter affecting the mixture fraction field for the short premixing length. Stability results showed that the level of mixture inhomogeneity mainly influenced the flame stability. High flame stability is achieved if a large portion of the inhomogeneous mixture fraction is within the fuel flammability limits.
  • Ammonia and ammonia/hydrogen blends oxidation in a jet-stirred reactor: Experimental and numerical study

    Osipova, Ksenia N.; Zhang, Xiaoyuan; Sarathy, Mani; Korobeinichev, Oleg P.; Shmakov, Andrey G. (Fuel, Elsevier BV, 2021-10-18) [Article]
    One of the most important problems of modern energy industry is the transition to carbon free fuels, which can mitigate the negative environmental effects. This paper presents experimental data on ammonia and ammonia/hydrogen blends oxidation in an isothermal jet-stirred reactor over the temperature of range 800–1300 K. Experiments were performed under atmospheric pressure, residence time of 1 s, various equivalence ratios, and with argon dilution at ≈0.99. It was revealed that hydrogen addition shifts the onset temperature of ammonia oxidation by about 250 K towards the lower region. A detailed chemical kinetic model which showed the best predictive capability was used to understand the effect of hydrogen addition on ammonia reactivity. It was shown that hydrogen presence results into higher concentrations of H, O and OH radicals. Moreover, these radicals start to form at lower temperatures when hydrogen is present. However, the change of the equivalence ratio has only slight effect on the temperature range of ammonia conversion.
  • Thermal Sensor Calibration for Unmanned Aerial Systems Using an External Heated Shutter

    Virtue, Jacob; Turner, Darren; Williams, Guy; Zeliadt, Stephanie; McCabe, Matthew; Lucieer, Arko (Drones, MDPI AG, 2021-10-17) [Article]
    Uncooled thermal infrared sensors are increasingly being deployed on unmanned aerial systems (UAS) for agriculture, forestry, wildlife surveys, and surveillance. The acquisition of thermal data requires accurate and uniform testing of equipment to ensure precise temperature measurements. We modified an uncooled thermal infrared sensor, specifically designed for UAS remote sensing, with a proprietary external heated shutter as a calibration source. The performance of the modified thermal sensor and a standard thermal sensor (i.e., without a heated shutter) was compared under both field and temperature modulated laboratory conditions. During laboratory trials with a blackbody source at 35 °C over a 150 min testing period, the modified and unmodified thermal sensor produced temperature ranges of 34.3–35.6 °C and 33.5–36.4 °C, respectively. A laboratory experiment also included the simulation of flight conditions by introducing airflow over the thermal sensor at a rate of 4 m/s. With the blackbody source held at a constant temperature of 25 °C, the introduction of 2 min air flow resulted in a ’shock cooling’ event in both the modified and unmodified sensors, oscillating between 19–30 °C and -15–65 °C, respectively. Following the initial ‘shock cooling’ event, the modified and unmodified thermal sensor oscillated between 22–27 °C and 5–45 °C, respectively. During field trials conducted over a pine plantation, the modified thermal sensor also outperformed the unmodified sensor in a side-by-side comparison. We found that the use of a mounted heated shutter improved thermal measurements, producing more consistent accurate temperature data for thermal mapping projects.
  • How often should dead-reckoned animal movement paths be corrected for drift?

    Gunner, Richard M.; Holton, Mark D.; Scantlebury, David M.; Hopkins, Phil; Shepard, Emily L. C.; Fell, Adam J.; Garde, Baptiste; Quintana, Flavio; Gómez-Laich, Agustina; Yoda, Ken; Yamamoto, Takashi; English, Holly; Ferreira, Sam; Govender, Danny; Viljoen, Pauli; Bruns, Angela; van Schalkwyk, O. Louis; Cole, Nik C.; Tatayah, Vikash; Börger, Luca; Redcliffe, James; Bell, Stephen H.; Marks, Nikki J.; Bennett, Nigel C.; Tonini, Mariano H.; Williams, Hannah J.; Duarte, Carlos M.; van Rooyen, Martin C.; Bertelsen, Mads F.; Tambling, Craig J.; Wilson, Rory P. (Animal Biotelemetry, Springer Science and Business Media LLC, 2021-10-16) [Article]
    Abstract Background Understanding what animals do in time and space is important for a range of ecological questions, however accurate estimates of how animals use space is challenging. Within the use of animal-attached tags, radio telemetry (including the Global Positioning System, ‘GPS’) is typically used to verify an animal’s location periodically. Straight lines are typically drawn between these ‘Verified Positions’ (‘VPs’) so the interpolation of space-use is limited by the temporal and spatial resolution of the system’s measurement. As such, parameters such as route-taken and distance travelled can be poorly represented when using VP systems alone. Dead-reckoning has been suggested as a technique to improve the accuracy and resolution of reconstructed movement paths, whilst maximising battery life of VP systems. This typically involves deriving travel vectors from motion sensor systems and periodically correcting path dimensions for drift with simultaneously deployed VP systems. How often paths should be corrected for drift, however, has remained unclear. Methods and results Here, we review the utility of dead-reckoning across four contrasting model species using different forms of locomotion (the African lion Panthera leo, the red-tailed tropicbird Phaethon rubricauda, the Magellanic penguin Spheniscus magellanicus, and the imperial cormorant Leucocarbo atriceps). Simulations were performed to examine the extent of dead-reckoning error, relative to VPs, as a function of Verified Position correction (VP correction) rate and the effect of this on estimates of distance moved. Dead-reckoning error was greatest for animals travelling within air and water. We demonstrate how sources of measurement error can arise within VP-corrected dead-reckoned tracks and propose advancements to this procedure to maximise dead-reckoning accuracy. Conclusions We review the utility of VP-corrected dead-reckoning according to movement type and consider a range of ecological questions that would benefit from dead-reckoning, primarily concerning animal–barrier interactions and foraging strategies.
  • The Importance of Larval Stages for Considering Crab Microbiomes as a Paradigm for the Evolution of Terrestrialization

    Wale, Matthew; Daffonchio, Daniele; Fusi, Marco; Marasco, Ramona; Garuglieri, Elisa; Diele, Karen (Frontiers in Microbiology, Frontiers Media SA, 2021-10-15) [Article]
    The transition from an aquatic to a terrestrial lifestyle has evolved multiple times, and in numerous different phyla, in earth’s history. In many crab species, this process is still underway (Bliss and Mantel, 1968), providing a unique opportunity to study the evolution of terrestrialization, as well as the role of associated microbiomes during this process (Cannicci et al., 2020). Recently, Cannicci et al. (2020) reported on the potential importance of microbiomes in the transition of crabs, formally wholly aquatic species, to life, fully or in part, in terrestrial environments. The authors argue that symbiotic bacteria, such as those of gill and gut microbiomes, may play a key role in easing this transition, by helping crabs to overcome physiological and morphological challenges associated with conquering the terrestrial environment, such as impaired respiration and osmotic regulation, and a new, often primary plant-based low nitrogen diet. Here we focus on the microbiomes of crab larvae and their potential role for the evolution of terrestrialization. Crabs that are transitioning to life on land fall into two broad categories: terrestrial species that spend their whole adult life (except for larval release) on land independent of tidal inundation or freshwater bodies, and semi-terrestrial species that spend their adult life on land but are dependent on tidal inundation or freshwater (Burggren and McMahon, 1988; Anger, 1995). Many marine organisms form symbiotic relationships with microorganisms to aid life in extreme environments (Sogin et al., 2020). In line with the hologenome theory, this suggests that host-microbe interactions play an important role in an organism’s evolution, where the genes of both the host and its microbes co-evolve in the collective “holobiont” (Zilber-Rosenberg and Rosenberg, 2008), potentially allowing the colonization of formerly hostile environments (Bang et al., 2018). Microbial symbionts, as individual species or in mixed-species assemblages, are present in many crustaceans, such as the marine isopod Idotea balthica (diet-specific gut microbiomes, Mattila et al., 2014), the intertidal brachyuran crab Eriocheir sinensis (gill and gut microbiomes, Zhang et al., 2016), and the freshwater signal crayfish Pacifastacus leniusculus (intestinal bacteria, Hernández-Pérez et al., 2021). Given that microbial assemblages are often specific to certain organs of their hosts (Chomicki et al., 2020), symbioses have likely evolved in support of a specific function. The microbial assemblages associated with the guts of semi-terrestrial crabs have been proposed to aid in the adaptation of a low nitrogen, herbivorous diet during terrestrialization (Bui and Lee, 2015), like microbial assemblages of other aquatic invertebrates, e.g., isopods, where they enable the digestion of cellulose (Zimmer et al., 2002; O’Connor et al., 2014). The bacteria specifically associated with crab gills (Zhang et al., 2016, 2017) may facilitate ammonia excretion (Weihrauch et al., 2004), utilize gaseous CO2 (Morris, 2001), and buffer exposure to oxygen, which occurs at a concentration 30 times higher (Hsia et al., 2013) in the terrestrial compared to the marine environment where the host organism evolved. The microbiomes of both gut and gills could therefore provide terrestrial and semi-terrestrial crabs (here collectively called semi-/terrestrial) with means to cope with life in marine as well as in terrestrial environments. Whilst the presence of microbiomes and their role in buffering the stresses imposed on crabs by terrestrialization is beginning to be discussed (Bui and Lee, 2015; Cannicci et al., 2020), there are many unknowns. For example, the mode of bacterial acquisition, bacterial diversity, topological association, and the precise functions of their organ-specific microbial assemblages are still poorly understood, both for adult semi-/terrestrial crabs and their early life stages. Most semi-/terrestrial crab species, like their aquatic counterparts, have a biphasic life cycle including fully aquatic larvae, via which they transition to semi-/terrestrial juvenile/adult life (Anger, 1995; Hartnoll etal.,2014).Understanding microbial colonization of the larvae would likely provide critical insights into how these crabs have been able to move from water to land, and whether the bacteria themselves facilitate this transition.
  • Nickel-Catalyzed Reductive Cross-Couplings: New Opportunities for Carbon–Carbon Bond Formations through Photochemistry and Electrochemistry

    Yi, Liang; Ji, Tengfei; Chen, Kun-Quan; Chen, Xiang-Yu; Rueping, Magnus (CCS Chemistry, Chinese Chemical Society, 2021-10-15) [Article]
    Metal-catalyzed cross-electrophile couplings have become a valuable tool for carbon–carbon bond formation. This minireview provides a comprehensive overview of the recent developments in the topical field of cross-electrophile couplings, provides explanations of the current state-of-the-art, and highlights new opportunities arising in the emerging fields of photoredox catalysis and electrochemistry.
  • Efficient and chemoselective hydrogenation of aldehydes catalyzed by a well-defined PN3 -pincer manganese (II) catalyst precursor: an application in furfural conversion

    Huang, Kuo-Wei; Gholap, Sandeep S.; Al Dakhil, Abdullah; Chakraborty, Priyanka; Li, Huaifeng; Dutta, Indranil; Das, Pradip (Chemical Communications, Royal Society of Chemistry (RSC), 2021-10-15) [Article]
    Well-defined and air-stable PN3-pincer manganese (II) complexes were synthesized and used for the hydrogenation of aldehydes into alcohols under mild conditions using MeOH as a solvent. This protocol is applicable for a wide range of aldehydes containing various functional groups. Importantly, α,β-unsaturated aldehydes, including ynals, are hydrogenated with the C=C double bond/CΞC triple bond intact. Our methodology was demonstrated for biomass derived feedstock such as furfural and 2,5-diformyl furfural to furfuryl alcohol and 2-hydroxy furfuryl alcohol respectively.
  • Mind the Gap: Domain Gap Control for Single Shot Domain Adaptation for Generative Adversarial Networks

    Zhu, Peihao; Abdal, Rameen; Femiani, John; Wonka, Peter (arXiv, 2021-10-15) [Preprint]
    We present a new method for one shot domain adaptation. The input to our method is trained GAN that can produce images in domain A and a single reference image I_B from domain B. The proposed algorithm can translate any output of the trained GAN from domain A to domain B. There are two main advantages of our method compared to the current state of the art: First, our solution achieves higher visual quality, e.g. by noticeably reducing overfitting. Second, our solution allows for more degrees of freedom to control the domain gap, i.e. what aspects of image I_B are used to define the domain B. Technically, we realize the new method by building on a pre-trained StyleGAN generator as GAN and a pre-trained CLIP model for representing the domain gap. We propose several new regularizers for controlling the domain gap to optimize the weights of the pre-trained StyleGAN generator to output images in domain B instead of domain A. The regularizers prevent the optimization from taking on too many attributes of the single reference image. Our results show significant visual improvements over the state of the art as well as multiple applications that highlight improved control.
  • Mind the Gap: Domain Gap Control for Single Shot Domain Adaptation for Generative Adversarial Networks

    Zhu, Peihao; Abdal, Rameen; Femiani, John; Wonka, Peter (arXiv, 2021-10-15) [Preprint]
    We present a new method for one shot domain adaptation. The input to our method is trained GAN that can produce images in domain A and a single reference image I_B from domain B. The proposed algorithm can translate any output of the trained GAN from domain A to domain B. There are two main advantages of our method compared to the current state of the art: First, our solution achieves higher visual quality, e.g. by noticeably reducing overfitting. Second, our solution allows for more degrees of freedom to control the domain gap, i.e. what aspects of image I_B are used to define the domain B. Technically, we realize the new method by building on a pre-trained StyleGAN generator as GAN and a pre-trained CLIP model for representing the domain gap. We propose several new regularizers for controlling the domain gap to optimize the weights of the pre-trained StyleGAN generator to output images in domain B instead of domain A. The regularizers prevent the optimization from taking on too many attributes of the single reference image. Our results show significant visual improvements over the state of the art as well as multiple applications that highlight improved control.
  • Lethal variants in humans: lessons learned from a large molecular autopsy cohort.

    Shamseldin, Hanan E; AlAbdi, Lama; Maddirevula, Sateesh; Alsaif, Hessa S; AlZahrani, Fatema; Ewida, Nour; Hashem, Mais; Abdulwahab, Firdous; Abuyousef, Omar; Kuwahara, Hiroyuki; Gao, Xin; Molecular Autopsy Consortium; Alkuraya, Fowzan S (Genome medicine, Springer Science and Business Media LLC, 2021-10-14) [Article]
    BackgroundMolecular autopsy refers to DNA-based identification of the cause of death. Despite recent attempts to broaden its scope, the term remains typically reserved to sudden unexplained death in young adults. In this study, we aim to showcase the utility of molecular autopsy in defining lethal variants in humans.MethodsWe describe our experience with a cohort of 481 cases in whom the cause of premature death was investigated using DNA from the index or relatives (molecular autopsy by proxy). Molecular autopsy tool was typically exome sequencing although some were investigated using targeted approaches in the earlier stages of the study; these include positional mapping, targeted gene sequencing, chromosomal microarray, and gene panels.ResultsThe study includes 449 cases from consanguineous families and 141 lacked family history (simplex). The age range was embryos to 18 years. A likely causal variant (pathogenic/likely pathogenic) was identified in 63.8% (307/481), a much higher yield compared to the general diagnostic yield (43%) from the same population. The predominance of recessive lethal alleles allowed us to implement molecular autopsy by proxy in 55 couples, and the yield was similarly high (63.6%). We also note the occurrence of biallelic lethal forms of typically non-lethal dominant disorders, sometimes representing a novel bona fide biallelic recessive disease trait. Forty-six disease genes with no OMIM phenotype were identified in the course of this study. The presented data support the candidacy of two other previously reported novel disease genes (FAAH2 and MSN). The focus on lethal phenotypes revealed many examples of interesting phenotypic expansion as well as remarkable variability in clinical presentation. Furthermore, important insights into population genetics and variant interpretation are highlighted based on the results.ConclusionsMolecular autopsy, broadly defined, proved to be a helpful clinical approach that provides unique insights into lethal variants and the clinical annotation of the human genome.
  • An Efficient Metal-Organic Framework - Derived Nickel Catalyst for the Light Driven Methanation of CO2

    Khan, Il Son; Mateo, Diego; Shterk, Genrikh; Shoinkhorova, Tuiana; Poloneeva, Daria; Garzon Tovar, Luis Carlos; Gascon, Jorge (Angewandte Chemie, Wiley, 2021-10-14) [Article]
    We report the synthesis of a highly active and stable metal-organic framework derived Ni-based catalyst for the photo-thermal reduction of CO 2 to CH 4 . Through the controlled pyrolysis of MOF-74 (Ni), the nature of the carbonaceous species and therefore photo-thermal performance can be tuned. CH 4 production rates of 488 mmol g -1 h -1 under UV–visible-IR irradiation are achieved when the catalyst is prepared under optimized conditions. No particle aggregation or significant loss of activity were observed after five consecutive reaction cycles. Finally, as a proof-of-concept, we performed an outdoor experiment under ambient solar irradiation, demonstrating the potential of our catalyst to reduce CO 2 to CH 4 using only solar energy.
  • On the Formation of Hydrogen Peroxide in Water Microdroplets

    Jr., Adair Gallo; Musskopf, Nayara H.; Liu, Xinlei; Yang, Zi Qiang; Petry, Jeferson; Zhang, Peng; Thoroddsen, Sigurdur T; Im, Hong G.; Mishra, Himanshu (arXiv, 2021-10-14) [Preprint]
    Recent reports on the formation of hydrogen peroxide (H2O2) in water microdroplets produced via pneumatic spraying or capillary condensation have garnered significant attention. How covalent bonds in water could break under such conditions challenges our textbook understanding of physical chemistry and the water substance. While there is no definitive answer, it has been speculated that ultrahigh electric fields at the air-water interface are responsible for this chemical transformation. Here, we resolve this mystery via a comprehensive experimental investigation of H2O2 formation in (i) water microdroplets sprayed over a range of liquid flowrates, the (shearing) air flow rates, and the air composition (ii) water microdroplets condensed on hydrophobic substrates formed via hot water or humidifier under controlled air composition. Specifically, we assessed the contributions of the evaporative concentration and shock waves in sprays and the effects of trace O3(g) on the H2O2 formation. Glovebox experiments revealed that the H2O2 formation in water microdroplets was most sensitive to the air-borne ozone (O3) concentration. In the absence of O3(g), we could not detect H2O2(aq) in sprays or condensates (detection limit ≥250 nM). In contrast, microdroplets exposed to atmospherically relevant O3(g) concentration (10–100 ppb) formed 2–30 μM H2O2(aq); increasing the gas–liquid surface area, mixing, and contact duration increased H2O2(aq) concentration. Thus, the mystery is resolved –the water surface facilitates the O3(g) mass transfer, which is followed by the chemical transformation of O3(aq) into H2O2(aq). These findings should also help us understand the implications of this chemistry in natural and applied contexts.
  • Experimental evaluation of liquid nitrogen fracturing on the development of tight gas carbonate rocks in the Lower Indus Basin, Pakistan

    Ali, Muhammad; Shar, Abdul Majeed; Mahesar, Aftab Ahmed; Al-Yaseri, Ahmed; Yekeen, Nurudeen; Memon, Khalil Rehman; Keshavarz, Alireza; Hoteit, Hussein (Fuel, Elsevier BV, 2021-10-13) [Article]
    Tight gas carbonate formations have enormous potential to meet the supply and demand of the ever-growing population. However, it is impossible to produce from these formations due to the reduced permeability and lower marginal porosity. Several methods have been used to extract unconventional tight gas from these reservoirs, including hydraulic fracturing and acidizing. However, field studies have demonstrated that these methods have environmental flaws and technical problems. Liquid nitrogen (LN2) fracturing is an effective stimulation technique that provides sudden thermal stress in the rock matrix, creating vivid fractures and improving the petro-physical potential. In this study, we acquired tight gas carbonate samples and thin sections of rock from the Laki limestone formation in the Lower Indus Basin, Pakistan, to experimentally quantify the effects of LN2 fracturing. Initially, these samples were characterized based on mineralogical (X-ray diffraction), petrography, and petro-physical (permeability and porosity) properties. Additionally, LK-18-06 Laki limestone rock samples were exposed to LN2 for different time intervals (30, 60, and 90 mins), and various techniques were applied to comprehend the effects of the LN2 before and after treatment, such as atomic force microscopy, scanning electron microscopy, energy-dispersive spectroscopy, nano-indentation, and petro-physical characterization. Our results reveal that the LN2 treatment was very effective and induced vivid fractures of up to 38 µm. The surface roughness increased from 275 to 946 nm, and indentation moduli significantly decreased due to the decreased compressibility of the rock matrix. Petro-physical measurements revealed that the porosity increased by 47% and that the permeability increased by 67% at an optimum LN2 treatment interval of 90 mins. This data can aid in an accurate assessment of LN2 fracturing for the better development of unconventional tight gas reservoirs.
  • Catalyst- and Additive-Free Approach to Constructing Benzo-oxazine, Benzo-oxazepine, and Benzo-oxazocine: O Atom Transfer and C═O, C–N, and C–O Bond Formation at Room Temperature

    Ghosh, Arnab; Hegde, Rajeev V.; Rode, Haridas B.; Ambre, Ram; Mane, Manoj Vasisht; Patil, Siddappa A.; Sridhar, Balasubramanian; Dateer, Ramesh B. (Organic Letters, American Chemical Society (ACS), 2021-10-13) [Article]
    An exclusive synthesis of benzo-oxazine, benzo-oxazepine, and benzo-oxazocine from aryl propanal and 2-(hydroxyamino)phenyl alcohol under metal-free conditions is described. O atom transfer and formation of new C═O, C-N, and C-O bonds occur at room temperature to form six-, seven-, and eight-membered heterocycles under one-pot reaction conditions without using an external oxidant and base. The photophysical properties are studied using ultraviolet-visible absorption and photoluminescence. The mechanistic elucidation is well supported by control experiment and literature precedents.
  • Extending the natural adaptive capacity of coral holobionts

    Voolstra, Christian R.; Suggett, David J.; Peixoto, Raquel S; Parkinson, John E.; Quigley, Kate M.; Silveira, Cynthia B.; Sweet, Michael; Muller, Erinn M.; Barshis, Daniel J.; Bourne, David G.; Aranda, Manuel (Nature Reviews Earth & Environment, Springer Science and Business Media LLC, 2021-10-12) [Article]
    Anthropogenic climate change and environmental degradation destroy coral reefs, the ecosystem services they provide, and the livelihoods of close to a billion people who depend on these services. Restoration approaches to increase the resilience of corals are therefore necessary to counter environmental pressures relevant to climate change projections. In this Review, we examine the natural processes that can increase the adaptive capacity of coral holobionts, with the aim of preserving ecosystem functioning under future ocean conditions. Current approaches that centre around restoring reef cover can be integrated with emerging approaches to enhance coral stress resilience and, thereby, allow reefs to regrow under a new set of environmental conditions. Emerging approaches such as standardized acute thermal stress assays, selective sexual propagation, coral probiotics, and environmental hardening could be feasible and scalable in the real world. However, they must follow decision-making criteria that consider the different reef, environmental, and ecological conditions. The implementation of adaptive interventions tailored around nature-based solutions will require standardized frameworks, appropriate ecological risk–benefit assessments, and analytical routines for consistent and effective utilization and global coordination.
  • A New Thiophene-Appended Fluorescein-Hydrazone-Based Chromo-Fluorogenic Sensor for the Screening of Hg 2+ Ions in Real Water Samples

    Roy, Swapnadip; Mondal, Tapashree; Dey, Dhananjay; Mane, Manoj Vasisht; Panja, Sujit S. (ChemistrySelect, Wiley, 2021-10-12) [Article]
    A simple yet efficient, Hg2+ selective sensor, based on a fluroescein-thiophene conjugate, namely, (Z)-3′,6′-dihydroxy-2-(((3-methylthiophen-2-yl)methylene)amino)spiro[isoindoline-1,9′-xanthen]-3-one (FT) has been designed and synthesized. The compound was well characterized by analytical techniques such as HR-MS, FTIR, UV-visible absorption, steady-state fluorescence and time-resolved spectrophotometric techniques. Comprehensive analysis demonstrated FTas a highly specific and ultra-sensitive sensor towards Hg2+ ions in presence of several other interfering metal ions in ethanol/H2O (9 : 1, v/v) at pH=7.2 buffered with 10 mM HEPES buffer at room temperature. The complexation of the probe FT with Hg2+ was well confirmed by ESI-MS and FTIR spectral analysis. The detection limit of the probe FT towards Hg2+ was achieved down to 137 nM. The structure of ligand FT and FT-Hg2+ complex were well corroborated by theoretical studies as well. In addition, the FT-Hg2+ complex was found to be reversible in presence of di-sodium EDTA and hence decipher its recyclability capabilities. The significance of the present probe FT lies in its successful application for the detection and quantification of Hg2+ in real water samples and logic gate fabrication for future incorporation in small organic molecule based efficient molecular devices.
  • Enhancing Fracture Network Characterization: A Data-Driven, Outcrop-Based Analysis

    Zhu, Weiwei; He, Xupeng; Santoso‬, ‪Ryan Kurniawan; Lei, Gang; Patzek, Tadeusz; Wang, Moran (Wiley, 2021-10-11) [Preprint]
    The stochastic discrete fracture network (SDFN) model is a practical approach to model complex fracture systems in the subsurface. However, it is impossible to validate the correctness and quality of an SDFN model because the comprehensive subsurface structure is never known. We utilize a pixel-based fracture detection algorithm to digitize 80 published outcrop maps of different scales at different locations. The key fracture properties, including fracture lengths, orientations, intensities, topological structures, clusters and flow are then analyzed. Our findings provide significant justifications for statistical distributions used in SDFN modellings. In addition, the shortcomings of current SDFN models are discussed. We find that fracture lengths follow multiple (instead of single) power-law distributions with varying exponents. Large fractures tend to have large exponents, possibly because of a small coalescence probability. Most small-scale natural fracture networks have scattered orientations, corresponding to a small κ value (κ<3) in a von Mises--Fisher distribution. Large fracture systems collected in this research usually have more concentrated orientations with large κ values. Fracture intensities are spatially clustered at all scales. A fractal spatial density distribution, which introduces clustered fracture positions, can better capture the spatial clustering than a uniform distribution. Natural fracture networks usually have a significant proportion of T-type nodes, which is unavailable in conventional SDFN models. Thus a rule-based algorithm to mimic the fracture growth and form T-type nodes is necessary. Most outcrop maps show good topological connectivity. However, sealing patterns and stress impact must be considered to evaluate the hydraulic connectivity of fracture networks.

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