Cobweb Research Articles

Interferometric measurement of arbitrary propagating vector beams that are tightly focused.

In this work, we demonstrate a simple setup to generate and measure arbitrary vector beams that are tightly focused. The vector beams are created with a spatial light modulator and focused with a microscope objective with an effective numerical aperture of 1.2. The transverse polarization components (Ex, Ey) of the tightly focused vector beams are measured with three-step interferometry. The axial component Ez is reconstructed using the transverse fields with Gauss's law. We measure beams with the following polarization states: circular, radial, azimuthal, spiral, flower, and spider web.

Jumping spider invades an orb web to prey on a resident male

AbstractWhile surveying operational sex ratios of the giant golden orb weaverNephila pilipes(Fabricius, 1793) in Singapore, we documented a stunning case of predatory behavior of a jumping spiderViciria pavesiiThorell, 1877. A femaleV. pavesiiinvaded aN. pilipesorb web that was occupied by the resident female and four males, and successfully captured, killed, and removed one of theNephilamales. Whether araneophagy inV. pavesiiis opportunistic or a predatory ritual remains to be tested more precisely, but because the observed predatory event triggered an aggressive response by theN. pilipesalpha male, it is plausible thatV. pavesiimay engage in aggressive mimicry. We place our observation into the context of jumping spider cognition and behavioral tactics that are so far well understood only in a few spartaeine genera, notablyPortiaKarsch, 1878.ViciriaThorell, 1877, we argue, is another such jumping spider taxon worthy of behavioral scrutiny.

An Integrated Model of WebQual 4.0 and SERVQUAL: Answer to the Next Research Call

In the original paper of WebQual 4.0, Barnes and Vidgen (2002) called for an improvement of their WebQual 4.0 model. Since WebQual 4.0 is a tool for assessing the quality of e-commerce websites, therefore a modification should be made in order to use WebQual 4.0 for other types of websites. This research offers an integrated model of WebQual 4.0 and SERVQUAL to fulfill the need. The proposed integrated model resulted in seven variables: Usability, Design, Information, Empathy, Responsiveness, Assurance, and Reliability. To test the model, a questionnaire based on the proposed model was created to assess the quality of a company website that is primarily used to manage employees’ data. There were 124 data samples that can be used for analysis. A spider web diagram was created based on the reliability (Cronbach’s alpha) scores to show the overall website quality. Based on the confirmatory factor analysis (CFA) results, it can be concluded that the integrated model that was created in this research was considered a good model. The implications and lessons learned from the study were discussed in the paper.

Assessment of the Role of Leasehold Forest in Livelihood Improvement in Gorkha District, Nepal

The leasehold forestry aims to free the poor from a complicated cycle of poverty by institutionalizing and manipulating the local resources. This study is based on the structured and semi-structured questionnaire and an examination of both published and unpublished records. The study was carried out in 283 Leasehold Forest User Groups (LHFUGs) of the Gorkha district representing 8 different clusters. This study makes a clear effort to identify livelihood improvement in the Gorkha district through leasehold forest by taking into consideration livelihood assets (natural, physical, human, financial, and social). The condition of livelihood capitals in the study area was examined using a judgmental scoring technique that looked at the changes that occurred in five different capitals. Three indicators have been used for each of the assets and scores; +1, -1, and 0 were given to represent improved, degraded, and remained unchanged respectively. A spider web diagram was used to express the change. The results depicted that Chepang, Gurung, and Magar are the predominant indigenous peoples who benefited from the LHF. The result showed the constructive impact of the leasehold forestry program on each asset. The social, physical, human, natural and financial capital received an average total score of 0.778, 0.951, 0.748, 0.589, and 0.722 respectively. The most notable accomplishments were construction and access to the physical capitals including the effectiveness of constructions and advancement of knowledge about community development. Better-managed natural resources can help achieve both conservation and livelihood options.

Effects of energy density on microstructure evolution and electromagnetic interference shielding efficiency of laser cladding Fe84Nb7B9 alloy

To develop Fe-based alloy materials with high electromagnetic shielding properties to meet the demand for the preparation of new electromagnetic shielding materials, Fe84Nb7B9 alloy with high electromagnetic shielding properties was prepared by laser cladding using the elemental powder method. The microstructure evolution and electromagnetic shielding properties of samples prepared with different laser energy densities were studied. The results show that the energy density has an important impact on the printability and electromagnetic shielding performance of the prepared samples. Under the optimized laser energy density of 119 J/mm2, the Fe84Nb7B9 alloy sample with good printability was successfully prepared and has the highest electromagnetic shielding performance of 87 dB. The mechanism of high electromagnetic shielding performance of the sample is determined by the synergistic effect of dielectric loss and ohmic loss due to different phase structures, among them, the α-Fe phase mainly promotes dielectric loss, while the "spider web" phase structure composed of α-Fe, NbFeB and Fe2B phase enhances ohmic loss. This study provides a useful reference for the preparation of high electromagnetic shielding Fe-Nb-B alloy by laser cladding.

Experimental and numerical study on crashworthiness of bionic hedgehog spine thin-walled structures

Natural impact-resistant biomaterials, with ingenious and exquisite geometric configurations, have resistance to external impact, and thus provide a perfect bionic example for the optimization design and crashworthiness improvement of new thin-walled structures. Based on the configuration characteristics of hedgehog spine, this paper designed the bulkheaded hedgehog spine thin-walled structure and studied the dynamic behavior of thin-walled structures under axial and oblique impact compression by combining 3D metal printing, quasi-static compression test and finite element simulation. The results show that the combined effect of the ribs, inner walls and bulkheads of the bulkheaded hedgehog spine thin-walled structure effectively improves its deformation coordination ability and crashworthiness. The specific energy absorption of the bulkheaded hedgehog spine thin-walled structure under axial or oblique impact is about 4.1, 2.1 and 1.4 times that of the single-wall cylinder, spider web and simplified hedgehog spine thin-walled structures, respectively.

Phylogenomics illuminates the evolution of orb webs, respiratory systems and the biogeographic history of the world’s smallest orb-weaving spiders (Araneae, Araneoidea, Symphytognathoids)

The miniature orb weaving spiders (symphytognathoids) are a group of small spiders (<2 mm), including the smallest adult spider Patu digua (0.37 mm in body length), that have been classified into five families. The species of one of its constituent lineages, the family Anapidae, build a remarkable diversity of webs (ranging from orbs to sheet webs and irregular tangles) and even include a webless kleptoparasitic species. Anapids are also exceptional because of the extraordinary diversity of their respiratory systems. The phylogenetic relationships of symphytognathoid families have been recalcitrant with different classes of data, such as, monophyletic with morphology and its concatenation with Sanger-based six markers, paraphyletic (including a paraphyletic Anapidae) with solely Sanger-based six markers, and polyphyletic with transcriptomes. In this study, we capitalized on a large taxonomic sampling of symphytognathoids, focusing on Anapidae, and using de novo sequenced ultraconserved elements (UCEs) combined with UCEs recovered from available transcriptomes and genomes. We evaluated the conflicting relationships using a variety of support metrics and topology tests. We found support for the phylogenetic hypothesis proposed using morphology to obtain the “symphytognathoids'' clade, Anterior Tracheal System (ANTS) Clade and monophyly of the family Anapidae. Anapidae can be divided into three major lineages, the Vichitra Clade (including Teutoniella, Holarchaea, Sofanapis and Acrobleps), the subfamily Micropholcommatinae and the Orb-weaving anapids (Owa) Clade. Biogeographic analyses reconstructed a hypothesis of multiple long-distance transoceanic dispersal events, potentially influenced by the Antarctic Circumpolar Current and West Wind Drift. In symphytognathoids, the ancestral anterior tracheal system transformed to book lungs four times and reduced book lungs five times. The posterior tracheal system was lost six times. The orb web structure was lost four times independently and transformed into sheet web once.

Graphene Oxide/Nitrocellulose Non-Covalent Hybrid as Solid Phase for Oligo-DNA Extraction from Complex Medium.

A nitrocellulose-graphene oxide hybrid that consists of a commercially nitrocellulose (NC) membrane non-covalently modified with graphene oxide (GO) microparticles was successfully prepared for oligonucleotide extraction. The modification of NC membrane was confirmed by Fourier Transform Infrared Spectroscopy (FTIR), which highlighted the principal absorption bands of both the NC membrane at 1641, 1276, and 835 cm-1 (NO2) and of GO in the range of 3450 cm-1 (CH2-OH). The SEM analysis underlined the well-dispersed and uniform coverage of NC membrane with GO, which displayed thin spider web morphology. The wettability assay indicated that the NC-GO hybrid membrane exhibited slightly lower hydrophilic behavior, with a water contact angle of 26.7°, compared to the 15° contact angle of the NC control membrane. The NC-GO hybrid membranes were used to separate oligonucleotides that had fewer than 50 nucleotides (nt) from complex solutions. The features of the NC-GO hybrid membranes were tested for extraction periods of 30, 45, and 60 min in three different complex solutions, i.e., an aqueous medium, an α-Minimum Essential Medium (αMEM), and an αMEM supplemented with fetal bovine serum (FBS). The oligonucleotides were desorbed from the surface of the NC-GO hybrid membrane using Tris-HCl buffer with a pH of 8.0. Out of the three media utilized, the best results were achieved after 60 min incubation of the NC-GO membranes in αMEM, as evidenced by the highest fluorescence emission of 294 relative fluorescence units (r.f.u.). This value corresponded to the extraction of approximately 330-370 pg (≈7%) of the total oligo-DNA. This method is an efficient and effortless way to purify short oligonucleotides from complex solutions.

Study on the Changes in Shielding Performance Based on Electrospinning Pattern Shapes in the Manufacturing Process of Polymer-Metal Composite Radiation Shielding Materials

X-rays are commonly employed in medical institutions for diagnostic examinations, which often results in radiation exposure for both patients and medical personnel during treatments and procedures. Hands are typically the most exposed body parts, with scattered rays causing secondary exposure. To address this issue, a lightweight functional radiation protection fabric that guarantees the activity of medical personnel is required. In this study, a shielding fabric was fabricated with nanofibers using a mixture of tungsten and polyurethane to resolve the weight reduction problem of such nanofibers. To improve the shielding performance, the change in the performance arising from the spinning pattern in the nanofiber electrospinning manufacturing process was compared and tracked. The patterns reproduced via electrospinning included honeycomb, matrix-orthogonal, double-circle, and spider web patterns. Through this, a nanofiber fabric was produced, and the shielding performance was evaluated. The honeycomb pattern fabric exhibited the best shielding rate of 89.21% at an effective X-ray energy of 60.3 keV, and the double-circle pattern exhibited the lowest shielding rate of 62.55% at the same energy. Therefore, it was observed that the pattern arising from the nanofiber spinning conditions affects the dispersion of the shielding material, which affects the shielding performance. When 0.3 mm tungsten nanofiber fabric is compared with its lead equivalent of 0.25 mm, a difference of 8.7% was observed, suggesting that the nanofiber can be used in medical institutions. Future research will explore the potential of protective fabrics that minimally impact medical personnel’s mobility but provide enhanced protection against radiation exposure.

Visual antipredator effects of web flexing in an orb web spider, with special reference to web decorations.

Some visual antipredator strategies involve the rapid movement of highly contrasting body patterns to frighten or confuse the predator. Bright body colouration, however, can also be detected by potential predators and used as a cue. Among spiders, Argiope spp. are usually brightly coloured but they are not a common item in the diet of araneophagic wasps. When disturbed, Argiope executes a web-flexing behaviour in which they move rapidly and may be perceived as if they move backwards and towards an observer in front of the web. We studied the mechanisms underlying web-flexing behaviour as a defensive strategy. Using multispectral images and high-speed videos with deep-learning-based tracking techniques, we evaluated body colouration, body pattern, and spider kinematics from the perspective of a potential wasp predator. We show that the spider's abdomen is conspicuous, with a disruptive colouration pattern. We found that the body outline of spiders with web decorations was harder to detect when compared to spiders without decorations. The abdomen was also the body part that moved fastest, and its motion was composed mainly of translational (vertical) vectors in the potential predator's optical flow. In addition, with high contrast colouration, the spider's movement might be perceived as a sudden change in body size (looming effect) as perceived by the predator. These effects alongside the other visual cues may confuse potential wasp predators by breaking the spider body outline and affecting the wasp's flight manoeuvre, thereby deterring the wasp from executing the final attack.

Comparison of active and passive methods for atmospheric particulate matter collection: From case study to a useful biomonitoring tool

In this study we conducted air pollution monitoring using three different methods: active monitoring with the use of high volume aerosol sampler and biomonitoring with the use of lichens and spider webs. All of these monitoring tools were exposed to air pollution in Legnica city, a region of Cu-smelting in the SW Poland, which is well known for exceeding the environmental guidelines. Quantitative analysis was carried out for the particles collected by the three selected methods and concentrations of seven selected elements (Zn, Pb, Cu, Cd, Ni, As, Fe) were obtained. Concentrations found in lichens and in spider webs were directly compared and indicated significant differences between them, with higher amounts noted for spider webs. Then, in order to recognize the main pollution sources the principal component analysis was conducted and obtained results were compared. It resulted that spider webs and aerosol sampler, despite different mechanisms of accumulation, show similar sources of pollution – in this case – copper smelter. Additionally, the HYSPLIT trajectories and the correlations between metals in the aerosol samples also confirmed that this is the most probable source of pollution. This study can be considered innovative as these three air pollution monitoring methods were compared, which has never been conducted before, and their comparison gave satisfying results.

Study on liquid cooling heat dissipation of Li-ion battery pack based on bionic cobweb channel

According to the heat generation characteristics of lithium-ion battery, the bionic spider web channel is innovatively designed and a liquid-cooled heat dissipation model is established. Firstly, the lithium-ion battery pack at 3C discharge rate under the high temperature environment of 40 °C is numerically simulated under the condition of coolant Re of 100. Secondly, the temperature distribution of the battery pack at different discharge rates (1C-4C) is analyzed. Although the temperature difference of the battery pack can be better controlled at the end of discharge rate at 3C, the temperature difference of the battery pack exceeds 5 °C in the first 600 s of discharge process, so four different coolant flow arrangement schemes are designed. The results show that the reasonable flow arrangement scheme (b) can effectively improve the temperature uniformity of the battery pack. Finally, the coolant inlet Re is investigated. The results show that there exists a critical Reynolds number which guarantees a maximum temperature of 38.6 °C at the end of the discharge process and maintains the temperature uniformity of the battery pack at around 2 °C, the coolant pressure drop is only 0.78 Pa. The battery thermal management model designed in this paper both controls the maximum battery temperature and satisfies the temperature uniformity of the battery pack.

Which side are you on? Spider web positioning affects prey capture more than body colour

Colour has been hypothesized to play a crucial role in prey capture for sit-and-wait predators that rely on visual cues to deceive their prey. Prey capture success has been directly linked to colouration in spiders; however, evidence so far focuses mostly on dorsal colouration, excluding ventral patterns that are visible to prey and may be relevant for prey attraction. Here, we explored whether the dorsal and ventral colouration of a colour polymorphic spider is associated with light environment and prey capture success. We quantified the number of prey captured across three dorsal (black, white, and yellow) and two ventral (black and a mosaic yellow/orange pattern) morphs of Gasteracantha cancriformis, considering light intensity on dorsal and ventral sides. We found that spiders capture more prey in low light environments, and that individuals often expose their dorsal colouration towards low light levels. We did not find significant differences in prey capture rate between morphs dorsally or ventrally. These results indicate that how and where spiders position their web can be more important for prey capture than colouration. Alternative hypotheses such as aposematism, camouflage and thermoregulation deserve more attention in future studies that aim to understand the role of colouration in spiders and the factors causing spider colour polymorphisms.

Dual-emitting from Bi[formula omitted], Ln[formula omitted] (Ln [formula omitted] Eu, Sm) co-activated Ca[formula omitted]Sb[formula omitted]O[formula omitted] phosphor for optical temperature measurement

In this paper, a series of Ca(2−x−y) Sb2O7: xBi3+, yLn3+ (Ln = Eu, Sm) fluorescent powder samples were successfully obtained, which used the traditional high-temperature solid-phase synthesis method in the preparation process. Samples of Ca2Sb2O7: Bi3+, Ln3+ (Ln = Eu, Sm) fluorescent powder samples were structurally and optically characterized​ using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), photoluminescence excitation spectroscopy and emission spectroscopy, and fluorescence decay measurements. The results show that the prepared Ca(2−x−y) Sb2O7: xBi3+, yLn3+ (Ln = Eu, Sm) samples have an orthogonal spider web structure, which remains unchanged whether Bi3+ is single doped or Bi3+ is co-doped with Ln3+ (Ln = Eu, Sm). Under ultraviolet lamp (λex=340nm) irradiation, Bi3+ doped Ca2Sb2O7 powder shows a wide emission band centered at 435 nm, which is owing to the 3P1→1S0 transition of Bi3+ ion. Therefore, the effect of Bi3+ and Ln3+ (Ln = Eu, Sm) co-doped Ca2Sb2O7 samples on the luminescence intensity of the samples at different concentrations was studied. When the temperature was varied from 293 K to 483 K, the absolute temperature sensitivity (Sa) of doped Bi3+/Eu3+ and Bi3+/Sm3+ phosphors is 0.001K−1 (at 483 K) and 0.02K−1 (at 293 K), respectively, and the relative temperature sensitivity (Sr) is 1.03% K−1 (at 343 K) and 1.19% K−1 (at 293 K), respectively. These results demonstrate that Ca(2−x−y) Sb2O7: xBi3+, yLn3+(Ln = Eu, Sm) phosphors are prospective double emission thermal thermometers.

Aunty Next Door - A Qualitative Study of Community Prevention and Control for COVID-19

Introduction:The Thai government has established public health policies to cope with COVID-19 and reduce the spread of disease by promulgating the Emergency Decree since March 26th 2019 in concept “stay at home, stop the spread of the virus for the sake of nation.” Those measures had been affected to people in all social levels whether it be urban or rural. The objective of this qualitative study was aimed to study the mechanisms and experiences of village health volunteers who work to control COVID-19 at the community level.Method:Forty village health volunteers in the 8th health region were included in the study. Data collection by using focus group discussion combined with audio recordings and the data were analyzed by content analysis.Results:The community’s context in the upper northeastern region of Thailand live in kinship. This is a factor supporting the operation of village health volunteers (VHVs) in the surveillance, prevention, and control of disease in the community. The mechanisms for disease prevention and control in the community are a virtual "Spider web" that connects people in the community, VHVs, Community Leaders, Public Health Officers, and Sub-district Administrative Organization (SAO) officers that operate together. While people in the community, especially "women", act in surveillance in the form of "watchdogs" that report abnormalities of community member movements to the VHV for coordination in surveillance, prevention, and control of disease in their community. The VHV and partners use management guidelines as prescribed by the Ministry of Public Health and adapted to the social and cultural context.Conclusion:The community's COVID-19 surveillance mechanism that mediates kinship begins with fear and panic from a lack of knowledge in the early stages of the outbreak. The kinship of people in the community is one of the strengths and factors of success in preventing and controlling the disease.

Robber Barons and Wretched Refuse: Ethnic and Class Dynamics during the Era of American Industrialization

Robber Barons and Wretched Refuse: Ethnic and Class Dynamics during the Era of American Industrialization

Invasive brown widow spiders avoid parasitism despite high densities.

Invasive species are sometimes less susceptible to natural enemies compared to native species, but the mechanism is often unclear. Here we tested two potential mechanisms for lower parasitism of invasive species: density-dependent parasitism and preference for human-dominated habitats. We investigated how variation in host density and habitat type affect egg sac parasitismintwo widow spider species (family Theridiidae). We compared parasitism on the egg sac of the brown widow,Latrodectus geometricus, an urban invasive species, and the white widow,Latrodectus pallidus, a species native to Israel. To investigate variation in host and parasitoid density, we measured nearest-neighbor distance between spider webs and parasitism rates in 16 sites, and in a single site monthly throughout a year. In L. pallidus, denser sites were more heavily parasitized (up to 55%) and parasitism rate increased with population density throughout the season. Extremely dense L. geometricus populations, however, had very low rates of parasitism (0-5%). We then conducted an egg sac transplant experiment in human-dominated and natural habitats. We found no parasitism of either species in the human-dominated habitat, compared to 30% parasitism of both species in the natural habitat. In addition, we found evidence for higher predation of L. pallidus than of L. geometricus egg sacs, particularly in the natural habitat. These combined results suggest that the human-dominated habitats inhabited by L. geometricus have a lower abundance of predators and parasites. We conclude that lower parasitism and predation in human-dominated habitats could contribute to the invasion success of L. geometricus.

Agelena orientalis (Araneae: Agelenidae: Ageleninae) Huni Ağ Örümceğinin Ağ Yapısı ve Örü Aygıtının Morfolojisi

Örümceklerin ağ yapma özelliği çok eski yıllardan beri insanoğlunu etkilemiştir. Ancak bütün örümcekler ağ örmezler. Örümcekler ağ örme yeteneklerini örü aygıtlarına sahip olmalarına borçludur. Örü aygıtı ipek salgısını üreten ağ bezleri ve bu bezlere bağlı örü memelerinden oluşmaktadır. Örü memeleri, ipeğin çıkartılması ve iplik haline getirilerek işlenmesi için kullanılmaktadır. Örümceklerin ağları çok dikkat çekse de örü aygıtları hakkında çok fazla çalışma bulunmamaktadır. Bu çalışmada, oldukça dikkat çekici ağ yapısına sahip olan Agelena orientalis (C.L. Koch, 1837) huni ağ örümceğinin ağ yapısı ve ağ örme aygıtının morfolojisi taramalı elektron mikroskobu (SEM) ile çalışılmıştır. Çalışmamızda, A. orientalis’in ağ yapısı, örü memeleri ve spigotların yapısı gösterilmiş ve elde edilen veriler tartışılmıştır.

Improving reservoir permeability by electric pulse controllable shock wave

Controllable shock wave (CWS) parameters such as amplitude, operating area and number of operations are easy to control and have received extensive attention as a potential new technology for reservoir permeability enhancement. Based on the continuous-discontinuous element method (CDEM) and considering the coupling mechanism of reservoir deformation, failure, pore seepage and fracture flow, a multiphysical field coupling model of reservoir permeability enhancement under CWS is proposed. Under the fluid–solid coupling condition, the formation and development dynamic process of reservoir fractures are obtained, and the change of reservoir permeability is also obtained. The compression fracture zone, tensile fracture zone and undamaged zone are formed around the wellbore. After repeated impact, the number of fractures is more sensitive to tectonic stress, the fracture aperture is more sensitive to reservoir strength. Different from hydraulic fracturing, a large number of fractures in different directions will appear around the main fracture after repeated impact, forming a complex fracture network similar to spider web, which may be beneficial to improve reservoir permeability. The permeability of reservoirs with different tectonic stresses and strengths increases nonlinearly and monotonicly with repeated impacts. Based on CDEM, the change of reservoir permeability with tectonic stress, strength and impact times is obtained, which is a nonlinear monotonic three-dimensional relationship. Based on that relationship, the parameters of CWS can be controlled to predict the change of reservoir permeability, such as peak pressure, duration, impact times, etc. Therefore, it can optimize the reservoir fracturing scheme and improve the reservoir fracturing efficiency, which has considerable practical significance in engineering.

Interfacial Capillary Spooling of Conductive Polyurethane-Silver Core-Sheath (PU@Ag) Microfibers for Highly Stretchable Interconnects.

Conductive fibers are core materials in textile electronics for the sustainable operation of devices under mechanical stimuli. Conventional polymer-metal core-sheath fibers were employed as stretchable electrical interconnects. However, their electrical conductivity is severely degraded by the rupture of metal sheaths at low strains. Because the core-sheath fibers are not intrinsically stretchable, designing a stretchable architecture of interconnects based on the fibers is essential. Herein, we introduce nonvolatile droplet-conductive microfiber arrays as stretchable interconnects by employing interfacial capillary spooling, motivated by the reversible spooling of capture threads in a spider web. Polyurethane (PU)-Ag core-sheath (PU@Ag) fibers were prepared by wet-spinning and thermal evaporation. When the fiber was placed on a silicone droplet, a capillary force was generated at their interface. The highly soft PU@Ag fibers were fully spooled within the droplet and reversibly uncoiled when a tensile force was applied. Without mechanical failures of the Ag sheaths, an excellent conductivity of 3.9 × 104 S cm-1 was retained at a strain of 1200% for 1000 spooling-uncoiling cycles. A light-emitting diode connected to a multiarray of droplet-PU@Ag fibers exhibited stable operation during spooling-uncoiling cycles.