Controllable assembly of continuous hollow graphene fibers with robust mechanical performance and multifunctionalities

Macroscopic conformation of individual graphene sheets serves as the backbone of translating their intrinsic merits towards multifunctional practical applications. However, controllable and continuous assemblies of graphene-based nanomaterials to create stable macroscopic structural components are always in face of great challenge. We have developed a scalable converging-flow assisted wet-spinning methodology for continuously fabricating hollow graphene fibers (HGFs, the newest variation of solid graphene fibers) with high quality. The degradable silk thread is selectively utilized as the continuous hollow structure former that holds the coaxially stacked graphene sheets aligned through the converging-flow modulating process. For the first time, we have created the longest freestanding HGF in length of 2.1 m. The continuous HGFs are in an average diameter of 180 μm and with 4-8 μm adjustable wall thicknesses. The optimal HGF demonstrates an average tensile strength of 300 MPa and modulus of 2.49 GPa (comparable to typical solid graphene fibers, but the highest among the reported HGFs in literature) and an exceptional failure elongation of 10.8%. Additionally, our continuous HGFs exhibit spontaneous resistive response to thermal and strain stimuli (in form of large deformations and human motions), offering great potential for developing multifunctional sensors. We envision that this work demonstrates an effective and well-controlled macroscopic assembly methodology for the scaled-up mass production of HGFs.

Darwin's bark spider shares a spidroin repertoire with Caerostris extrusa but achieves extraordinary silk toughness through gene expression

Spider silk is a protein-based material whose toughness suggests possible novel applications. A particularly fascinating example of silk toughness is provided by Darwin's bark spider ( Caerostris darwini ) found in Madagascar. This spider produces extraordinarily tough silk, with an average toughness of 350 MJ m −1 and over 50% extensibility, and can build river-bridging webs with a size of 2.8 m 2 . Recent studies have suggested that specific spidroins expressed in C. darwini are responsible for the mechanical properties of its silk. Therefore, a more comprehensive investigation of spidroin sequences, silk thread protein contents and phylogenetic conservation among closely related species is required. Here, we conducted genomic, transcriptomic and proteomic analyses of C. darwini and its close relative Caerostris extrusa . A variety of spidroins and low-molecular-weight proteins were found in the dragline silk of these species; all of the genes encoding these proteins were conserved in both genomes, but their genes were more expressed in C. darwini . The potential to produce very tough silk is common in the genus Caerostris , and our results may suggest the existence of plasticity allowing silk mechanical properties to be changed by optimizing related gene expression in response to the environment.

An Investigation on a Coptic Embroidered Panel from the 13th Century “Crucifixion with the Twelve Apostles” (Benaki Museum, Athens)

The “Crucifixion with the twelve Apostles”, a unique Coptic embroidered panel, was on display at the Benaki Museum (Athens, Greece). The representation of the “Crucifixion” with Christ in the center and six Apostles on either side, standing next to each other in frontal poses, is quite a rare one. This rare iconographic image of the twelve Apostles could be linked to the Ascension or the Pentecost. This unique representation of the Crucifixion with the twelve Apostles, which also involves the Ascension, is a one-of-a-kind compositional formula representing Christ’s Death as a triumph over Death, emphasizing, along with the other factors, its non-Chalcedonic origin. Moreover, the interpretation of an inscription, written in at least three languages embroidered in black silk thread, is a matter which confuses the issue even more. In the present study, we will attempt a comprehensive investigation, a detailed description, and interpretation of this rare iconography, based on written and iconographic evidence traced in the history of art heritage objects.

A mixture of red kidney beans (Phaseolus vulgaris L.) and bee bread of honey bees (Wallacetrigona incise) as artificial feed for silkworm (Bombyx mori L.)

The supply of silk thread in Indonesia is only able to meet 5% of the national demand, and 95% must import it. Success in silk thread production comes from natural silk cultivation activities, namely mulberry cultivation. Meanwhile, the productivity of mulberry leaves in Indonesia is very low. This study aims to determine the feeding ability, growth of silkworm resistance, the effect of cocoon productivity pro4duced by silkworms when fed artificial feed. This research was conducted at the Forest Protection and Entomology Laboratory, Hasanuddin University. Artificial feed formulation in the form of a mixture of red kidney beans and bee bread with the comparison of mulberry leaves, red kidney beans, and bee bread were P1 (33:24:25), P2 (45:24:15); P3 (mulberry leaves and red kidney beans 40:44), P4 (mulberry leaves and bee bread 40:44), and P5 (natural feed of fresh mulberry leaves as control). Treatments P1, P2, P3, and P4 were added agar, vitamin C, sugar, and 100 ml of distilled water. The results of this study indicate that the percentage of artificial feed can be consumed 3 g/larva/day. Parameters of 5th instar larval survival, growth index, and cocoon quality in all feed compositions showed no significant differences.

Study of Antibacterial effects on Indian Currency

Indian currency is the official currency of India. With the advancement of science and technology several modes of cashless transaction have been introduced to our country but still a large section of our society is dependent on the transaction through currency notes. The composition of the Indian currency generally comprises of cotton rags, balsam and parts of silk for the purpose of security threads. These currency notes are a hidden threat to us as they transmit bacteria, virus and fungus through touch and gets transmitted from one person to another. An Indian note changes hands in an average of 500 times a day therefore increasing the chances of contaminating the currency getting high and the transmission of harmful diseases through this currency also increases. When these highly contaminated Indian currencies comes in contact with the human touch it results in the transmission of harmful bacteria into the humans therefore causing several bacteria prone diseases such as food poisoning diarrhoea Gonorrhoea, meningitis, ulcers, and several other diseases. Therefore, it is important to make the Indian currency antibacterial. The main focus of the study is to develop an antibacterial chemical agent which comprises of certain natural as well as chemical components as a solution which will be used to activate the antibacterial properties of the natural fibres present in the currency. Several investigations were carried out on how the natural ingredients that is of lemon extracts, industrial vinegar and ginger extract would act on the surface of the currency notes. Bleach was used to chlorinate the note as the fibroin fibres gets activated of the silk thread when chlorine treatment is done and it kills about 99.9% of the bacteria including E. coli and S. aureus. The application of the natural extracts on the surface of the currency showed specific changes as it was instantly more clear than previous condition. The acidic and the antibacterial properties of the natural ingredients used, makes the currency note bacteria free as well as dirt free for a certain period of time which is a notifiable change. The treated currency were seen to be preventing the growth of bacteria for a certain period of time because of the activation of antibacterial properties of silk fibres due to the application of chlorine on silk and also the application of natural ingredients therefore preventing the growth of bacteria by persisting on the outer surface of the currency.

Device for modeling of intra-arterial circulation: application in experimental cardiology

Purpose of study Using an original device for modeling of intra-arterial blood circulation, to study the features of intravascular hemodynamics with a regular heart rhythm and with various rhythm disturbances. Material and methods We used an original device developed by us to simulate intra-arterial circulation (Document of invention No. RU 202780 U1). The main part of the device is a glass tube of a rotameter with a length of 365 mm, an inlet end with a diameter of 20 mm, an outlet end of 16.5 mm, which is a model of an arterial vessel. Flexible silicone tubes are attached to the rotameter on both sides, with free ends connected to an electric pump, with various modes of operation (imitation of pulse waves with regular rhythm, premature ventricular contractions (PVCs), atrial fibrillation (AF). An aqueous solution of glycerin was introduced into a closed system diluted with water corresponding to the viscosity of the blood. A 5 mm long silk thread was alternately installed inside the tube, an intravascular piezoelectric crystal pressure probe connected to an oscilloscope. Also it was injected inside the tube a dye - clerical ink. Results With electric pump, we simulated the spreading of the pulse wave in regular heart rate, PVCs and AF. We observed the effect of a pressure wave (deflection of a silk thread, the appearance of a turbulent flow when using a dye) on the walls of the rotameter, with the formation of standing, reflected waves during the PVCs and AF. The pressure probe registered an increase in pressure inside the tube during the spread of the 1st post-extrasystolic contraction wave up to 58%, the wave after a long pause of more than 2 seconds with AF by 44% compared to the regular rhythm. Conclusion A device for modeling of intra-arterial circulation allows a wide range of experimental work in cardiology, normal and pathological physiology, and biophysics. FUNDunding Acknowledgement Type of funding sources: None.

Results of studyıng the effect of feed qualıty of ıntroduced multıple varıetıes on technologıcal ındıcators of cocoon

The article provides information on the technological features of cocoons obtained from silkworms fed on the leaves of mulberry varieties imported from different countries. We are talking about raw silk yield, total length of cocoon wire, metric number of silk thread, dry cocoon yield from live cocoon, raw silk yield indicators. These indicators may differ depending on the hereditary characteristics of different varieties. Keywords: Mulberry, sort, introduction, cocoon, raw silk yield, silkiness, metric number

Textile Dyes from Gokstad Viking Ship’s Grave

The grave from Gokstad in Norway, dating to ca 900 AD, is one of the best-preserved Viking Age ship graves in the world. The grave mound contained a variety of goods along with human remains, buried in a Viking ship. Several textiles, including embroideries and shreds of what might have been the ship’s tent, were also found. The colors of the textile fragments are now severely faded, but the high quality of the embroidery made of gold and silk threads is still apparent. The style of the embroidery is exceptional, having no equivalents in other Scandinavian graves. The analyses by HPLC coupled with both diode array and mass spectrometric detectors revealed that the striped “tent” cloth as well as the silk thread used for the embroidery were originally dyed with anthraquinones of plant origin (alizarin, purpurin, pseudopurpurin, and anthragallol), markers of madder-type dyestuffs.

A study of ladder-like silk foothold for the locomotion of bagworms

While walking on horizontal substrates, caterpillars skilfully engage all their legs, including three pairs of thoracic legs and a maximum of five pairs of prolegs, to move in a flexible wave-like motion. Such locomotory behaviours, represented by ‘crawling’ and ‘inching’ motions, have widely inspired the development of locomotion systems in soft robotics. However, bagworms are unable to use their prolegs for walking because these are always accommodated in a portable bag; thus, they are unable to walk using such general locomotory behaviours. Indeed, how they walk with only three pairs of thoracic legs is unknown at present. In this study, we show that bagworms construct a ladder-like foothold using their silk to walk without using prolegs. This enables them to walk not only on horizontal floor surfaces but also on wall and ceiling surfaces, even those with slippery or smooth surfaces. They construct the foothold by spinning a continuous silk thread in a zigzag manner and controlling the discharge of adhesive to attach the folded parts of the silk to a substrate. Discovery of this elaborate silk utilisation technique offers fresh insights into the diversity of silk use in lepidopteran larvae and provides potential designs for robot locomotion systems.