Cobweb Research Articles

Halloween day! a molossid bat trapped in a communal spider web in the Paraná flooded savanna of eastern Argentina

Halloween day! a molossid bat trapped in a communal spider web in the Paraná flooded savanna of eastern Argentina

When spiders take over: the expulsion of giant Amazonian ants from their nest

Spiders have been documented using nests of various ant species. In this study, we recorded the non-harmonious use of a nest and the expulsion of giant Amazonian ants from their nest by a Diplura spider. Both species inhabit South American forests, including the Amazon rainforest and Cerrado. This event took place in the northern Cerrado of Brazil during the rainy season. The expropriation process lasted 13 days, beginning with the simultaneous occupation of the anthill and culminating in the complete eviction of the ants. Over the last two days, we observed intense ant activity at a second entrance to the anthill and the construction of a new nest. We propose that the funnel-web spider was using the ant nest as shelter. However, the simultaneous coexistence may have been limited due to the spider web blocking an entrance and dietary overlap leading to competitive exclusion.

Spider waste enhances soil nutrient content, soil respiration, and plant growth

Abstract Predators can alter the movement of nutrients through ecosystems by depositing waste products following predation. Whilst the benefits of predator waste for large predators (e.g. bears) or dense accumulations of predators (e.g. seabirds on islands) seem clear, less is known about whether smaller, solitary predators can have measurable effects on local ecosystem processes. In separate experiments with web‐building and wandering spiders, we tested if the presence of predators affected soil nutrient content, soil respiration, soil microbial communities, and plant growth. In the first experiment with black widow spiders, total nitrogen and nitrate were not affected by spider presence, but ammonia and phosphorus were higher from soil under the edge of the spider web than soil away from the spider. Soil respiration and plant growth were both higher in soil collected from under the spider retreat compared with soil collected away from the spider web. In a second experiment with wolf spiders, we tested for interactions between spiders and soil microbial communities. There were positive effects of wolf spider presence on all soil nutrients and there were interactions between spiders and soil type (i.e. field‐collected versus autoclaved) for total carbon, total nitrogen, nitrate, and pH. Spider presence and soil type also affected soil respiration and spider presence had a large effect on the composition of the microbial community of the soil. There were also positive effects of wolf spider presence on plant biomass and plant height, with a significant interaction between spiders and soil type for plant height. Overall, our results show that two spiders with different life histories (i.e. web‐building and wandering) both have significant positive effects on plant growth through the deposition of their waste products. These effects may occur through the direct deposition of nutrients and changes in soil microbial communities. Although, further work is needed to resolve these interactions. Read the free Plain Language Summary for this article on the Journal blog.

Leading two-point resistances from transfer matrices in cylindrical, spider web, axial and grid resistor networks

Resistor networks are increasingly being considered in heuristic research as models for natural or artificial matter. The equivalent resistance between two nodes, the Two-Point Resistance (TPR), can be calculated using a variety of methods. The transfer matrix (TM) method was originally considered as a numerical tool for estimating percolation thresholds in random networks with a repeating pattern. The TM method is revisited here as an efficient tool to obtain, in a fast and elegant way, iteration relations and exact explicit expressions for leading TPRs that include a node in the last repeated pattern. Several rotationally invariant networks are studied, such as simple cylindrical networks, spider web networks and cylindrical networks with a central resistive axis, in which case the TM matrices are circulant matrices. Examples of explicit expressions are given for orders of rotation ≤4 or 5, depending on the case. The method can be applied in a similar way to networks with less symmetry, such as grids. The general expressions of TPRs obtained using the TM method can provide quantitative guidelines for resistor networks developed in materials science, environmental issues or industrial applications.

Spider Webs‐Inspired Aluminum Coordination Hydrogel Piezoionic Sensors for Tactile Nerve Systems

AbstractPiezoionics, a new frontier that employs mobile ions as energy and charge carriers, plays an important role in new energy and intelligent electronics. However, a significant challenge consists in balancing the structural design of metal ions coordination hydrogel (HG‐MI) piezoionics for current conduction, voltage generation, and especially mechanical adaptability. Herein, inspired by the spider webs' unique structure, a strategy by realizing the full potential of metal‐ligand ions ([(OH)Cl2]3−) to facilitate the keggin‐type structure AlOHAlOH generation together with activate functional carboxyls is introduced. Impressively, the whole property of the product HG‐AlPAC, especially the mechanical performance is improved. For example, the toughness of HG‐AlPAC is 2.75 MJ m−3, more than twofold that of traditional HG‐AlAS/AC/AN samples. Due to the stable fixation of ─Al─OH─ thus promoting Cl− separation upon external force, HG‐AlPAC achieves a piezoionic coefficient of 0.89 mV KPa−1 and energy conversion efficiency of 1.29%, promising for mechanical‐electrical conversion and sensing. Combined with the good mechanical performance with the excellent piezoionic properties, underscores its potential as a tactile nerve system of analgesia patients to prevent them from being injured. This work intends to provide a stride toward mechanically robust self‐powered piezoionic sensors and offer insights into ionotropic materials for energy harvesting, human‐machine interaction, and biointerface.

Unchained Catenaries

Summary Catenaries are the curves formed by a uniform chain or cable suspended from two ends. They are seen in the natural world in structures such as spider webs, and they also occur in engineered structures, including bridges and overhead power lines. Catenaries and catenary arches are also employed in architecture for their beauty and strength. In this article, we look at catenaries where a chain is fixed at one endpoint but free to move over the other. Such catenaries will either be supported by the weight of the tail end of the chain and hence be “stable,” or else unwind off the free end and adopt the configuration of a vertically hanging chain. We develop two models, which are analyzed to determine the conditions under which a particular system will be either stable or unstable and determine the widest span for which a stable catenary exists. The predictions made here may be explored experimentally with relatively inexpensive apparatus. The models presented also invite extensions, such as more general free point locations and the addition of friction, which could dissipate the system energy.

Bioinspired Photoluminescent "Spider Web" as Ultrafast and Ultrasensitive Airflow-Acoustic Bimodal Sensor for Human-Computer Interaction and Intelligent Recognition.

Nature provides massive biomimetic design inspiration for constructing structural materials with desired performances. Spider webs can perceive vibrations generated by airflow and acoustic waves from prey and transfer the corresponding information to spiders. Herein, by mimicking the perception capability and structure of a spider web, an ultrafast and ultrasensitive airflow-acoustic bimodal sensor (HOF-TCPB@SF) is developed based on the postfunctionalization of hydrogen-bonded organic framework (HOF-TCPB) on silk film (SF) through hydrogen bonds. The "spider web-like" HOF-TCPB@SF possesses light weight and high elasticity, endowing this airflow sensor with superior properties including an ultralow detection limit (DL, 0.0076 m s-1), and excellent repeatability (480 cycles). As an acoustic sensor, HOF-TCPB@SF exhibits ultrahigh sensitivity (105140.77 cps Pa-1 cm-2) and ultralow DL (0.2980 dB), with the greatest response frequency of 375 Hz and the ability to identify multiple sounds. Moreover, both airflow and acoustic sensing processes show an ultrafast response speed (40 ms) and multiangle recognition response (0-180°). The perception mechanisms of airflow and acoustic stimuli are analyzed through finite element simulation. This bimodal sensor also achieves real-time airflow monitoring, speech recognition, and airflow-acoustic interoperability based on human-computer interaction, which holds great promise for applications in health care, tunnel engineering, weather forecasting, and intelligent textiles.

Wood derived conductive aerogel with ultrahigh specific surface area and exceptional mechanical flexibility for pressure sensing

Conductive nanocellulose aerogels possess durability and sensitivity by using as piezoresistive sensors. Those aerogels are mostly prepared via a “bottom-up” strategy by using nanocellulose or dissolved and regenerated cellulose as raw materials. However, there is a pressing need to further enhance their sustainability and economic viability. To alleviate these issues, cellulose aerogel can alternatively be made via a “top-down” technique that entails the direct removal of contaminants from naturally porous biomass. Herein, conductive aerogels with exceptional mechanical flexibility and ultrahigh specific surface area were created. Delignified wood was partially dissolved and regenerated to created nanocellulose fibrils with spider web structure inside the pores of wood. After modification with silane coupling agent and carbon nanotubes (CNTs), flexible conductive wood aerogel (C-WA) were obtained. The specific surface area of C-WA was as high as 333.82 m2/g, which was 45 times of that of wood. C-WA could maintain its good resilience even after 1000 cycles, showing high compression resilience and excellent fatigue resistance (stress retention rate was 87.22%, height retention rate was 99.5%). The utilization of C-WA as a pressure sensor demonstrated remarkable attributes, including ultra-fast response and stability within the designated range. Furthermore, it exhibited exceptional sensing performance even after enduring 2000 stable cycles. The system is capable of real-time, accurate, and efficient detection of human motion signals, showcasing immense potential for future applications in wearable electronic products.

Progress in Multiscale Modeling of Silk Materials.

As a result of their hierarchical structure and biological processing, silk fibers rank among nature's most remarkable materials. The biocompatibility of silk-based materials and the exceptional mechanical properties of certain fibers has inspired the use of silk in numerous technical and medical applications. In recent years, computational modeling has clarified the relationship between the molecular architecture and emergent properties of silk fibers and has demonstrated predictive power in studies on novel biomaterials. Here, we review advances in modeling the structure and properties of natural and synthetic silk-based materials, from early structural studies of silkworm cocoon fibers to cutting-edge atomistic simulations of spider silk nanofibrils and the recent use of machine learning models. We explore applications of modeling across length scales: from quantum mechanical studies on model peptides, to atomistic and coarse-grained molecular dynamics simulations of silk proteins, to finite element analysis of spider webs. As computational power and algorithmic efficiency continue to advance, we expect multiscale modeling to become an indispensable tool for understanding nature's most impressive fibers and developing bioinspired functional materials.

Construction of a 3D spider web structure with spherical Ho2O3 wrapped by carbon nanofibers for high-efficiency microwave absorption and corrosion protection

Reasonable composition control and microstructure design are the effective ways to realize multi-functional high-performance absorbing materials. In this work, a three-dimensional (3D) spider web structure was designed by the electrospinning and high temperature carbonization technology, where Ho2O3 spheres were wrapped by carbon nanofibers. Herein, the spherical Ho2O3 were surrounded by layers of carbon nanofibers (spider silk), which were like the preys inside the spider's web. This unique bionic structure working in conjunction with the tuned components enables the as-prepared composites with improved impedance matching and enhanced loss capacity. The superior electromagnetic wave absorption performance was obtained as the minimum reflection loss of −61.37 dB at 2.90 mm and the maximum effective absorption bandwidth of 6.88 GHz (11.12–18 GHz) at 2.64 mm. At a thickness of 3.44 mm, the effective absorption bandwidth is 4.80 GHz (8–12.80 GHz), covering the entire X-band. At the same time, the composite soaked in the corrosive medium for 7 days owns a low corrosion current density (10−4 ∼10−6 A cm−2) and a high polarization resistance (105∼107 Ω), which exhibits the obvious anticorrosion ability. This work designs a specific spider web structure with high-performance microwave absorption and corrosion protection.

Perbandingan Konsep Integrasi Sains dan Agama Menurut Imam Prayogo dan M. Amin Abdullah

This research aims to find out the thoughts of Imam Prayogo and Amin Abdullah regarding the tree of knowledge and spider web models, to find out the differences in the thoughts of the two figures. By using data collection techniques in the form of studying and collecting data through reading materials sourced from primary books and secondary books related to the two figures discussed. This research uses a qualitative descriptive approach, and the type of research used is library research, namely collecting data or scientific writing aimed at the object of research or library data collection. From the research results, it was concluded that Imam Prayogo placed greater emphasis on the hierarchy and structure of knowledge rooted in revelation as the main foundation, with a focus on modernization and renewal of Islamic thought. Amin Abdullah, meanwhile, highlights the deep integration between Islamic and secular sciences in dealing with the complexities of contemporary life, placing the Qur'an and Sunnah at the center of his scientific framework.

Effect of spider's weight on signal transmittance in vertical orb webs.

Spider orb web is a sophisticated structure that needs to fulfil multiple roles, such as trapping prey and transmitting web-borne signals. When building their web, heavier spiders tend to increase the pretension on the web, which seems counterintuitive since a tighter web would decrease the chances of stopping and retaining prey. In this article, we claim that heavier orb-weaving spiders increase tension on the web in order to reduce the attenuation of the vibratory signal coming from the bottom part of the web. We support our claim by first building a detailed spider web model, which is tuned by a tension-adjusting algorithm to fit the experimentally observed profiles. Then, the effects of the spider weight and the web tension on the signal transmittance properties are investigated using state-of-the-art finite element analysis tools.

“Grasping on a spider web of hope”: Psychological challenges and impact of waiting to access UK gender dysphoria Clinics on young adults

Background Young transgender adults report higher levels of mental health difficulties compared to the general population. These difficulties reportedly improve following gender-affirming care and transition. However, gender-dysphoric people wait up to 5+ years in the UK to access gender-affirming treatment. Aims The study aimed to qualitatively explore the psychological challenges and impact of waiting to access UK Gender Dysphoria Clinics (GDCs) for young trans adults. Methods Recruitment via two GDCs resulted in a sample of 10 participants (aged 17–26) who had been waiting at least 12 months for assessment. Qualitative semi-structured interviews were conducted online or by phone with four men, four women, and two gender nonconforming people. Data were analyzed through Interpretive Phenomenological Analysis (IPA). Results Challenges and impact of waiting were represented within eight themes. Five psychosocial challenges included "Grasping on a spider web of hope that’s about to snap,” “People are uneducated and they don’t understand,” “Society or whatever made me second guess myself,” “I’m too autistic for that shit’, and “It sounded like the phone was just being left all day every day.” Mental health impacts of waiting were captured in the themes “(Gender) Dysphoria attacks” and “If it doesn’t go well by 30, I’m gonna kill myself.” A final theme, “I’m going to just go on with me life,” focused on healthy and less-adaptive coping strategies. Conclusion Waiting to access GDCs is a fragile and vulnerable time; experiences of discrimination, stigma, transphobia, and uncertainty during the waiting period appear to increase feelings of hopelessness and diminish mental health. Focusing on social transitioning was reported by most participants as a coping strategy for waiting. Findings highlight the importance of reducing waiting times for GDCs and offering psychosocial support during the wait.

Spider web-reinforced chitosan/starch biopolymer for active biodegradable food packaging

In this study, starch (ST), chitosan (CH), spider silk (SW), and their hybrid composite bioplastics were fabricated and examined for physicochemical and mechanical properties. The essential oils (EOs) of Rosmarinus officinalis were encapsulated to enhance their biological application. The prepared composite films were characterized using various spectroscopic techniques such as XRD, SEM, GCMS–, UV–VIS, TGA, and FTIR spectroscopy. The antimicrobial activity of the prepared film was tested against S. aureus bacterial and C. albican fungal strains which showed a greater zone of inhibition for the composite film encapsulated with EOs. The biodegradability of the synthesized film was evaluated for 60 days in soil under laboratory conditions. The composite film containing spider web and essential oil significantly improved mechanical properties. The physicochemical results, such as moisture, solubility, swelling, transmittance, opacity, and water vapor permeability, of the prepared bioplastic were comparable with those of the control plastic. The EO-based film had greater antioxidant activity against DPPH, hydrogen peroxide, and phosphomolybdenum assays, with an inhibition range of 60–70 %. The addition of spider web and essential oil to the chitosan/ starch film significantly increased the shelf life of injera and tomatoes for 7 and 10 days, respectively for the EO-based film. The biodegradability of the synthesized film has shown a great reduction in the weight and growth of microorganisms. In general, the CH/ST/SW and CH/ST/SW/EOs composite films have greater mechanical, biological, physicochemical, and potential improvement of food shelf life applied as either coating or packaging material.

Transformation of dry dipterocarp to dry evergreen forests alters food webs of web-building spiders and their prey

Anthropogenic habitat modification is a major contributor to global change. While the modification of natural habitats to agroecosystems attracts most of the attention, little is known about the conversion of one natural ecosystem to another. Dry dipterocarp forest is the key dry forest type across Southeast Asia. Moderate fire disturbance is essential for its regeneration, but humans often prevent fire in these forests. Consequently, dry dipterocarps can change to dry evergreen forests through succession. The consequences of this conversion on food webs are unknown. Using the network approach, we compared the food webs of web-building spiders and their prey in the understory between dry dipterocarp (open canopy, uniform understory) and dry evergreen forests (closed canopy, heterogeneous understory) in north-eastern Thailand. Overall, we collected 560 individual web-building spiders belonging to 37 genera. Further, we collected 1139 prey items from spider webs belonging to 16 arthropod orders. The composition of captured prey and the network structure differed between the forest types. Specifically, the web-building spiders were more specialized and their niches overlapped less in dry dipterocarps than in dry evergreens. The differences in food-web structure were driven mostly by trophic groups turnover rather than interaction rewiring. Implications for insect conservation: The transformation of dry dipterocarp to dry evergreen forests from the prevention of fire disturbance may lead to an altered ecological function of web-building spiders in forest understories. As trophic links and their strength are rewired, habitat modification may also lead to changes in nutrient and energy flow in forest understories.

Distribution of unit mass on one fractal self-similar web-type curve

In the article, we study structural, spectral, topological, metric and fractal properties of distribution of complex-valued random variable$\tau=\sum\nolimits_{n=1}^{\infty}\frac{2\varepsilon_{\tau}}{3^n}\equiv\Delta^g_{\tau_1...\tau_n...}$, where $(\tau_n)$ is a~sequence of independent random variables taking the values $0,1,\cdots,6$ with the probabilities $p_{0n}$, $p_{1n},\cdots,p_{6n}$; $\varepsilon_{6}=0$, $\varepsilon_0$, $\varepsilon_1,\cdots,\varepsilon_5$ are 6th roots of unity. We prove that the set of values of random variable $\tau$ is self-similar six petal snowflake which is a fractal curve $G$ of spider web type with dimension $\log_37$. Its outline is the Koch snowflake. We establish that $\tau$ has either a discrete or a singularly continuous distribution with respect to two-dimensional Lebesgue measure. The criterion of discreteness for the distribution is found and its point spectrum (set of atoms) is described. It is proved that the point spectrum is a countable everywhere dense set of values of the random variable $\tau$, which is the tail set of the seven-symbol representation of the points of the curve $G$. In the case of identical distribution of the random variables $\tau_n$ (namely: $p_{kn}=p_k$) we establish that the spectrum of distribution $\tau$ is a self-similar fractal and that the essential support of density is the fractal Besicovitch-Eggleston type set. The set is defined by terms digits frequencies and has the fractal dimension $\alpha_0(E)=\frac{\ln {p_0^{p_0}\cdots p_6^{p_6}}}{-\ln 7}$ with respect to the Hausdorff-Billingsley $\alpha$-measure. The measure is a probabilistic generalization of the Hausdorff $\alpha$-measure. In this case, the random variables $\tau=\Delta^g_{\tau_1\cdots\tau_n\cdots}$ and $\tau'=\Delta^g_{\tau_1'...\tau_n'...}$ defined by different probability vectors $(p_0,\cdots,p_6)$ and $(p'_0,\cdots,p'_6)$ have mutually orthogonal distributions.

Biomimetically spider web-like hydrogels for high-efficiency solar evaporators

With the increasing population, the shortage of freshwater resources has become a problem faced by human beings. Although many hydrogel solar evaporators achieved high evaporation rates by increasing the intermediate water content to reduce the enthalpy of water evaporation, it is still challenging to explore effective photothermal materials to construct efficient hydrogel solar evaporators. Here, inspired by the spider web structure, interconnected porous hydrogels were proposed by cross-linking heterojunctions and polymers. For the first time, MXene heterojunction is applied to solar evaporators. The introduction of SnS2 greatly improves the light absorption of MXene, at the same time, benefiting from the multi-scale macro/micro fiber network structure, MXene-SnS2 hydrogel (MSH) has a good “lock-in” performance, which makes the heat locally distributed near the evaporable water. As a result, the MSH evaporator has a low enthalpy of evaporation, with an evaporation rate of 3.3606 kg m−2 h−1 in 3.5 wt% salt water, and can maintain 1.9 kg m−2 h−1 even in 10.5 % brine. The evaporators present superior purification performance for seawater, could maintain high and stable evaporation performance for 72 h. This design principle and excellent performance provide a potential method and design concept for seawater desalination.

Claudio Fogu. The Fishing Net and the Spider Web: Mediterranean Imaginaries and the Making of Italians

Claudio Fogu. The Fishing Net and the Spider Web: Mediterranean Imaginaries and the Making of Italians

Performance evaluation of PV configurations considering degradation rate and hot spots

<p>The rapid emergence and evolution of renewable energy sources such as solar energy has become a vital component of the global effort to meet the energy needs of the future. The major concerns for continuous solar photovoltaic (PV) generation are degradation rate, hot spots. These factors lead to the negative impact on PV mismatch losses, fill factor, maximum power and efficiency. To improve the performance of PV system, the simplest solution is PV panel configuration hence in this paper spider web tie (SWT) based PV Panel configuration in proposed. The proposed configuration is implemented on KC200GT PV Panel of 5×5 size PV panels considering degradation rate, hot spot. The performance of SWT configuration is compared with series-parallel (SP), bridge-link (BL), triple tied (TT), and photovoltaic (PV) panel configurations and performance parameters such as Vmp, Imp, Pmp, Voc, Isc. FF, ∆Pml, and η are calculated in all the cases. In all the cases the proposed SWT configuration exhibited the improved performance.</p>

Exploring resource patch occupancy: patch size, but not connectivity, explains the abundance of spider kleptoparasites in golden orb webs

Exploring resource patch occupancy: patch size, but not connectivity, explains the abundance of spider kleptoparasites in golden orb webs