Cocoon Layer Research Articles

Mode III Tear Resistance of Bombyx mori Silk Cocoons.

This paper concerns the tear properties and behavior of Bombyx mori (B. Mori) silk cocoons. The tear resistance of cocoon layers is found to increase progressively from the innermost layer to the outermost layer. Importantly, the increase in tear strength correlates with increased porosity, which itself affects fiber mobility. We propose a microstructural mechanism for tear failure, which begins with fiber stretching and sliding, leading to fiber piling, and eventuating in fiber fracture. The direction of fracture is then deemed to be a function of the orientation of piled fibers, which is influenced by the presence of junctions where fibers cross at different angles and which may then act as nucleating sites for fiber piling. The interfaces between cocoon wall layers in B. mori cocoon walls account for 38% of the total wall tear strength. When comparing the tear energies and densities of B. mori cocoon walls against other materials, we find that the B. mori cocoon walls exhibit a balanced trade-off between tear resistance and lightweightness.

Effect of eIF6 on the development of silk glands and silk protein synthesis of the silkworm, Bombyx mori

The silkworm is a lepidopteran domesticated from the wild silkworm, mostly valued for its efficient synthesis of silk protein. This species' ability to spin silk has supported the 5500-year-old silk industry and the globally known “Silk Road”, making the transformation of mulberry leaves into silk of great concern. Therefore, research on the silk-related genes of silkworms and their regulatory mechanisms has attracted increasing attention. Previous studies have revealed that domestic silk gland cells are endoreduplication cells, and their high-copy genome and special chromatin conformation provide conditions for the high expression of silk proteins. In this study, we systematically investigate the expression pattern of eukaryotic initiation factors (eIFs) and identified the eIF6 as a eukaryotic translation initiation factor involved in the synthesis of silk proteins. We generated an eIF6 gene deletion mutant strain of silkworm using the CRISPR/Cas9 system and investigated the function of eIF6 in silk gland development and silk protein synthesis. The results showed that deletion of eIF6 inhibited the individual development of silkworm larvae, inhibited the development of silk glands, and significantly reduced the cocoon layer ratio. Therefore, we elucidated the function of eIF6 in the development of silk glands and the synthesis of silk proteins, which is important for further elucidation of the developmental process of silk glands and the mechanism underlying the ultra-high expression of silk proteins.

Cytotoxicity of AuCu-Cu2S Nanocomposites: Implications for Biological Evaluation of the Nanocomposite Effect on Bombyx mori Silkworms and Cell Lines.

AuCu-Cu2S nanocomposites are unique materials with exceptional properties that have recently received a lot of interest. However, little is known about their potential toxicity in terrestrial organisms and their subsequent effects on the environment. Therefore, it is essential to develop effective methodologies for evaluating AuCu-Cu2S nanocomposites in biological systems. This study reports the biological evaluation of the AuCu-Cu2S nanocomposite from animal and cell entity levels. The Bombyx mori silkworm was used as a model organism to study the effects of different concentrations of AuCu-Cu2S on silkworm development. Transcriptome analysis was also carried out to examine the genetic modulation exerted by the treatment. Moreover, biocompatibility and cytotoxicity of AuCu-Cu2S were evaluated in human bronchial epithelial cells 16HBE, human lung adenocarcinoma, and the insect Spodoptera frugiperda cell sf9 cell lines. The results showed that although AuCu-Cu2S at ≤400 ppm can prolong the eating habit of silkworms and promote the weight of the cocoon layer, there was an increase in silkworm mortality and a decrease in moth formation at a concentration of ≥800 ppm. The genetic regulation by AuCu-Cu2S treatment showed varying effects in the silkworm, primarily related to functions such as transport and catabolism, metabolism of cofactors and vitamins, xenobiotic biodegradation, amino acid, and carbohydrate. 16HBE, PC-9, and sf9 treated with 300 ppm of AuCu-Cu2S showed viability percentages of 60, 20, and 90%, respectively. Thus, AuCu-Cu2S at low concentrations serves as a safe and biocompatible material for the sf9 cell lines but is lethal to 16HBE and PC-9. This research could aid in understanding the biological effects and biocompatibility of AuCu-Cu2S nanocomposites, particularly in the field of biochemistry; however, the mechanisms involved need further exploration.

Fabrication, Structure, and Properties of Nonwoven Silk Fabrics Prepared with Different Cocoon Layers.

In this study, five different nonwoven silk fabrics were fabricated with silk fibers from different cocoon layers, and the effect of the cocoon layer on the structural characteristics and properties of the nonwoven silk fabric was examined. The diameter of the silk fiber and thickness of the nonwoven silk fabric decreased from the outer to the inner cocoon layer. More amino acids with higher hydrophilicity (serine, aspartic acid, and glutamic acid) and lower hydrophilicity (glycine and alanine) were observed in the outer layers. From the outer to the inner layer, the overall crystallinity and contact angle of the nonwoven silk fabric increased, whereas its yellowness index, moisture retention, and mechanical properties decreased. Regardless of the cocoon layer at which the fiber was sourced, the thermal stability of fibroin and sericin and good cell viability remained unchanged. The results of this study indicate that the properties of nonwoven silk fabric can be controlled by choosing silk fibers from the appropriate cocoon layers. Moreover, the findings in this study will increase the applicability of nonwoven silk fabric in the biomedical and cosmetic fields, which require specific properties for industrialization.

Dynamic Changes and Characterization of the Metal Ions in the Silk Glands and Silk Fibers of Silkworm

Metal ions are involved in the conformational transition of silk fibroin and influence the structure and mechanical properties of silk fibers. However, the dynamic characteristics of metal ions during the formation of silk fibers remain unclear. In this study, we found that the silk glands of silkworms contain various metal elements, with varying levels of the metal elements in different zones of the glands and higher levels in the anterior silk glands. Additionally, the content of various metallic elements in the silk glands varied greatly before and after spinning, similar to their content in different cocoon layers, thus, indicating that the anterior silk glands maintain a certain metal ion environment for the transport and conformational transformation of the silk proteins. Most of the metallic elements located in fibroin were confirmed using degumming experiments. For the first time, a scanning electron microscope energy spectrometry system was used to characterize the metal elements in the cross-section of silk and cocoons. These findings have deepened our understanding of the relationship between the overall metal ion environment and silk fiber formation and help us further conceptualize the utilization of metal ions as targets to improve the mechanical properties of the silk fibers.

ИССЛЕДОВАНИЕ ТЕМПЕРАТУРНЫХ РЕЖИМОВ ПРИ ХРАНЕНИИ ЖИВЫХ КОКОНОВ РАЗЛИЧНЫМИ СПОСОБАМИ

The article presents findings from experimental studies carried out in the industrial conditions to determine the rate of temperature change in various layers of cocoons when they are kept on the floor in bulk, in containers of a new design, which represents scientific and practical interest. Certain disadvantages of the existing method of storing the living cocoons have been observed. The ways of preventing self-heating of cocoons in the existing way of their storage are indicated. The findings show that when live cocoons are kept in containers of a new design, they can be stored for 2-3 days without shoveling and overheat to the extent that is considered acceptable in given storage methods. Application of the findings allows preserving the quality indicators of cocoons, which is an important indicator for making high-quality raw silk, which contributes to raise economic potential of the republic.

Natural Silkworm Cocoon-Based Hierarchically Architected Composite Triboelectric Nanogenerators for Biomechanical Energy Harvesting.

Silk-based triboelectric nanogenerators (TENGs) have been demonstrated as an ideal platform for self-powered systems. The source of silk, Bombyx mori, entails a valuable ingredient, sericin (SS), viewed as a binder in composites. Interestingly, SS is rich in the amorphous region, possibly resulting in triboelectrification enhancement between the amorphous region and the crystallization region when subject to external pressure. However, most researchers remove the SS component when designing silk-TENGs to eliminate immunological responses as implantation in vivo through complicated degumming, rehydration, and dialysis procedures. Herein, integral SS retention was utilized to fabricate silk-TENGs without affecting the output performance. We designed, for the first time, an ultra-robust and natural silkworm cocoon layer (SCL)/polydimethylsiloxane (PDMS)-TENG as an energy harvester to scavenge waste energy from human motions. The working mechanisms and influence of operational parameters are explored and studied. Working in the contact-separation mode, the electrical outputs of the SCL/PDMS-TENG in terms of open-circuit voltage, short-circuit current, and power density reaches 126 V, 3 μA, and 216 mW/m2, respectively. The integrated self-charging TENG is demonstrated to power small electronic electronics and monitor human motions. This work widens a new dielectric material selection with SS retention to boost the output performance of TENGs for practical applications.

Microstructural Characteristics of Eri Silk Fibre in Different Layers of Cocoon

ABSTRACT Five layers, i.e. floss, upper, middle, lower and pelade, exist in cocoon shell from outer to inner portion. An attempt has been made for assessment of microstructural characteristics of eri silk fiber in different layers of cocoons. Wide angle x- ray diffraction assessment revealed increase of crystallinity as well as degree of orientation and decrease in crystal size besides lattice spacing remains at par from floss to pelade layers. So, there is an improvement of single fibre tenacity and initial modulus from outer to inner position of cocoon’s shell. AFM assessment depicts increase in surface roughness of silk fibre from floss to pelade portion as observed from surface topography and root mean square average (Rq) of height deviation values. Descending trend of single fibre length and diameter were observed from floss to pelade layers along with significant reduction in lower and pelade layers vis-à-vis floss, upper and middle layers. Fibre quality index (FQI) can be measured from average single fibre length, fibre fineness and tenacity in five different layers. Expression has been derived for prediction of yarn tenacity from FQI and yarn count and good correlation exists between predicted and actual values.

Mechanism of silk secretion revealed by proteomic analysis of silkworm cocoons with fibroin light chain mutations

Silkworm is an economically important insect due to its efficient production of silk proteins. Silk itself and the silk trade have enriched human civilization through art and culture and contributed to early globalization in the Silk Road era for nearly two thousand years. Although a large number of studies on silk have been carried out, the mechanism of silk secretion in silkworms has not been thoroughly studied thus far. As the main component of fibroin, fibroin light chain (Fib-L) plays a key role in the secretion of silk. In this study, we constructed a homozygous Fib-L gene mutant population of a nonpractical variety using the CRISPR/Cas9 system. The homozygous mutants displayed a thin cocoon layer, but their viability was not affected by the Fib-L mutation. Furthermore, a comparative proteomic analysis of homozygous mutant cocoons and wild-type cocoons was performed. Strikingly, fibrohexamerin (P25) was secreted almost normally in the homozygous mutant. Further analysis of cocoon proteins revealed that the mutant responded to greater environmental stress caused by a dramatic decrease in fibroin by significantly increasing the secretion of protease inhibitors. These results will further help explain the silk secretion mechanism of silkworm. SignificanceThis study generated a homozygous Fib-L gene mutant population of a nonpractical variety using the CRISPR/Cas9 system. The homozygous mutants displayed a thin cocoon layer, but their viability was not affected by the Fib-L mutation. Furthermore, a comparative proteomic analysis of homozygous mutant cocoons and wild-type cocoons was performed. The analysis of the abundance of silk proteins in the cocoons revealed that P25 could be secreted almost normally. The analysis of the abundance of cocoon proteins other than silk proteins showed that the homozygous mutants responded to greater environmental stress by increasing the secretion of defense-related proteins, such as protease inhibitors. These results will further help explain the silk secretion mechanism of silkworm.

Silkworm Cocoon Layer with Gradient Structure as Separator for Lithium‐Ion Battery

Structural design of separator is becoming a strategy as attractive as material innovation for improving lithium‐ion batteries (LIBs) performance. Silkworm cocoon displays a very unique multilayer gradient structure in the thickness direction, but how the gradient structure in every single layer affects its separator properties is still unknown. Herein, the cocoon is initially peeled into various layers, and the differences in the composition, porosity, and packing density of each layer confirm the multilayer gradient structure of the cocoon. The thermal, puncture, wetting, and electrochemical properties of every layer are then investigated, and the relationship between structure and property is further analyzed. The performance is greatly dependent on the number of peeled layers and the layer position in the cocoon. Particularly, the puncture strength of the layered cocoon is better than the polyolefin separator and increases from the inner to the outer layer, while the wettability decreases. Moreover, the electrochemical performance of the cocoon layer is better than the unlayered cocoon with larger capacity retention. Therefore, it is hoped that such a study on the gradient structure and property of cocoon layers could provide inspiration for the separator design research focusing on the high safety and high performance for LIBs development.

Design and Study of Silk Cocoon-ZnO Micro-Nanocomposite based Gas Sensor for Detection of Flammable Gas at Room Temperature

In present work, a simple hydrothermal method is employed for the synthesis of silk cocoon-ZnO micro-nanocomposite and investigation of their gas sensing is reported. The ZnO nanoparticles were synthesized using hydrothermal methods and coated on the surface of silk cocoon layers using a simple doctor-blade method. The as-prepared silk cocoon-ZnO micro-nanocomposite materials were analyzed using X-ray diffractometer (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) and IV characteristics. The results confirm the formation of pure ZnO and silk cocoon-ZnO micro-nanocomposite with rod-like morphology. The surface of silk cocoon fibers was uniformly coated with ZnO nanorods. The gas sensing property of the as-prepared silk cocoon-ZnO micro-nanocomposite was evaluated against the leakage of LPG gas at room temperature. Voltage-Time curve analysis was performed and found that with the detection of LPG gas there is an increase in the voltage. Based on the present findings, it is proposed that silk cocoon-ZnO micro-nanocomposite based devices will be suitable for light weight, biocompatible and low-cost gas sensors.

An Experimental Analysis of Silk Cocoon Layer-PANI Polymer Composite as Electrode for Thermoelectric Generator Application

In this study, a silk cocoon layer (SCL) was surface coated with polyaniline (PANI), which serves as an electrode for thermoelectric generator (TEG) application. Here, the PANI was synthesized using the sol-gel method and coated on both sides of SCL using doctor-blade method. The efficiency of converting thermal energy into electrical energy was analyzed with a temperature range from 30 to 60 ºC. The TG-DTA analysis was performed to evaluate thermal stability. An evident change in the resistance was noticed for both cold (~5 °C) and heat (60 ºC) respective temperatures. Thus, this study provides a new biomaterial-based TEG electrode for waste heat recovery system/thermal management.

Comparative Analysis of Structure and Properties of Stereoscopic Cocoon and Flat Cocoon

Abstract Cocoon is a kind of natural biopolymer material with reasonable structure and various functions. However, its structure and functions are often destroyed in practical application. In this study, we took common Bombyx Mori as the research object, and provided different cocooning sites for single or multiple silkworms to construct common stereoscopic cocoons (“normal cocoons” [NC]) and flat cocoons (“single-silkworm flat cocoons” [SFC] and “multi-silkworm flat cocoons” [MFC]), respectively, and compared the morphological structure and basic properties of these cocoons. The study found that the flat cocoons have similar multi-layered variable structure and characteristics compared to those of the common cocoons; also, morphological characteristics and physical and chemical properties of silk fiber from outer layer to inner layer, such as sericin content, fiber fineness, and change rule of basic mechanical properties, are completely consistent with those of the common cocoons. It can be considered that the flat cocoons are constructed by silkworms in the same “procedural” process as that of common cocoons. Due to the expansion of cocooning space, the mechanical properties of fibers are significantly improved. By controlling the size of the cocooning space or the quantity of silkworms cocooning simultaneously, and the time of spinning, a cocoon material with controllable thickness, weight per square meter, porosity, and number of cocoon layers can be obtained as a composite material for direct application.

Relationship of parameters that characterize the quality of live cocoons

An important parameter for evaluating the technical and economic value of a batch of cocoons, along with silkiness (i.e., the ratio of the mass of shells to the mass of these cocoons as a percentage), is the volume stiffness of cocoons (i.e., the ratio of the external force acting on the cocoon to the amount of deformation of the cocoon shell). We propose to measure the volumetric stiffness using the FTI - 1M device, when an additional load is placed on the lid, which compresses the layer of live cocoons in the measuring container in height. It is obvious that the thinner the shell is, the greater the deformation of the cocoon layer will be. In addition, the volume stiffness was measured in this work by piece with a VC stiffener (i.e., a device for measuring the rigidity of the cocoon shell) separately for each breed with an error of 3%. These additional measurements confirmed the accuracy of the results obtained on the FTI - 1M device for volumetric stiffness. As a result, we obtained correlations between bulk stiffness and silkiness, as well as dependencies between bulk stiffness and shell thickness for various new breeds of silkworm cocoons: Marhamat, Marvarid, Asaka, and Yulduz. Linear dependencies are constructed based on the data presented in the corresponding table. The volume stiffness of various breeds of live cocoons increases both with increasing silkiness and the thickness of their shell. This is quite understandable, since the greater the silkiness, the thicker the shell, and therefore the greater the volume stiffness of the cocoon. Based on the results obtained, it is concluded that the silkiness of the Marvarid breed was lower than that of other breeds. Thus, this paper shows the possibility of determining the prospects of a particular breed by measuring and evaluating cocoons based on the correlation between silkiness and bulk stiffness or silkiness and the thickness of the shell of a cocoon sample.

Structure and Functions of Cocoons Constructed by Eri Silkworm.

Eri silkworm cocoons (E cocoons) are natural composite biopolymers formed by continuous twin silk filaments (fibroin) bonded by sericin. As a kind of wild species, E cocoons have characteristics different from those of Bombyx mori cocoons (B cocoons). E cocoons have an obvious multilayer (5–9 layers) structure with an eclosion hole at one end and several air gaps between the layers, which can be classified into three categories—cocoon coat, cocoon layer, and cocoon lining—with varying performance indexes. There is a significant secondary fracture phenomenon during the tensile process, which is attributed to the high modulus of the cocoon lining and its dense structure. Air gaps provide cocoons with distinct multistage moisture transmission processes, which form a good moisture buffer effect. Temperature change inside cocoons is evidently slower than that outside, which indicates that cocoons also have an obvious temperature damping capability. The eclosion hole does not have much effect on heat preservation of E cocoons. The high sericin content of the cocoon coat, as well as the excellent ultraviolet absorption and antimicrobial abilities of sericin, allows E cocoons to effectively prevent ultraviolet rays and microorganisms from invading pupae. The ultraviolet protection factor (UPF) of the E cocoon before and after degumming were found to be 17.8% and 9.7%, respectively, which were higher than those of the B cocoon (15.3% and 4.4%, respectively), indicating that sericin has a great impact on anti-UV performance. In the cocoon structure, the outer layer of the cocoon has 50% higher content than the inner layer, and the E cocoon shows stronger protection ability than the B cocoon. Understanding the relationship between the structure, property, and function of E cocoons will provide bioinspiration and methods for designing new composites.

Investigation on the microstructural characteristics and quasi-static puncture resistance of both domesticated and wild silkworm cocoons

The very thin and lightweight silkworm cocoon has outstanding mechanical properties attributed to its specific composite microstructure. However, the microstructures of the cocoons have not been studied quantitatively, and their anti-puncture performance has not been examined as well. In this study, both domesticated ( Bombyx mori) and wild silkworm cocoons ( Antheraea pernyi, Antheraea mylitta and Samia canningi) were investigated for their microstructures using fractal theory, and their quasi-static puncture resistance was tested and compared. In addition, the effects of cocoon layers and hot-press treatments on the puncture resistance of two cocoon types ( B. mori and A. pernyi) were investigated. The three wild cocoons demonstrated significantly higher fractal dimensions, higher fiber intersectional densities and low porosities, indicating their structures are more optimized. They also displayed better puncture resistance than B. mori. Increased layer numbers could significantly increase the puncture resistance of both cocoon types and A. pernyi showed more remarkable increases. Moreover, the two cocoon types showed optimum puncture resistance after heat treatment with hot-press temperature of 135℃ and pressure of 25 MPa, and A. pernyi showed better puncture resistance after such treatment. Finally, both the maximum puncture force and puncture energy of cocoons displayed a linear increase with the increasing fractal dimensions. The new insights can guide the development of novel protective fiber composites with desirable and predictable anti-puncture performance.

Review of the Characteristic Curves of Silkworm Cocoon Hot Air Dryingand Its Technological Configuration

To pass on Chinese cocoon-drying technology to developing countries, this paper reviews characteristic curves of silkworm cocoon hot air drying and its recent research advances in cocoon-drying technology in China based on the epochal and regional characters of cocoon drying technology development. (1) Three characteristic curves of cocoon drying are systematically explained, each of which can be divided into preheating, constant speed, and deceleration stages. The temperature susceptibility (i.e., the characteristics of response to temperature conditions) curve of the pupa successively shows heating, constant temperature, and heating processes. (2) Changes in the drying speed and temperature susceptibility of a fresh cocoon layer and naked pupae were examined in detail before and after pupae were killed in the preheating stage. It is proposed that heating the cocoons as soon as possible during the preheating stage of cocoon drying improves the work efficiency and cocoon quality. (3) The effects of the temperature and humidity of the hot air on the cocoon drying speed (i.e., speed coefficients) are obtained using the enthalpy psychrometric chart. The parameter configuration of cocoon drying technology is elaborated according to the speed coefficients in combination with the characteristic curves of cocoon drying and the influence of the laws of cocoon drying technology on cocoon quality. Furthermore problems in the technological configuration and the direction of future development are noted.

Studies on structural and fibre quality characteristics of eri silk cocoons in different seasons and places

Maximum mature larval, cocoon and shell weight were observed during winter season followed by spring and autumn seasons of both white and brick red eri cocoons. Cocoon weight and shell weight were found about 40 and 5%, respectively, as compared to mature larval weight. Degumming loss was estimated at about 10% for white eri and 12% for brick red eri cocoons. Weight of silk fibres varies significantly between layers and decreasing trend was noted from outer to inner layers. Similar trend was observed for single fibre denier and it differs significantly between places (ecoraces), seasons and layers of cocoons. Ascending trend for single fibre tenacity was found from floss to pelade layers of both white and brick red eri silk cocoons and significant influence was observed for places, seasons as well as layers whereas no impact was noted in case of single fibre breaking elongation. Regression equations between weight of degummed cocoon fibres, single fibre denier and single fibre tenacity and to its corresponding values for different places (ecoraces), seasons and cocoon layers were established and estimated R2 and ‘t’ values confirmed the significance of these regression equations.

In vivo bone regeneration ability of different layers of natural silk cocoon processed using an eco-friendly method

Silk cocoons are primarily composed of the proteins fibroin and sericin. To achieve guided bone regeneration (GBR), we have developed a simple and ecofriendly processing technique to obtain microperforated thin membranes from cocoons. The separated silk membranes composed of both fibroin and sericin were classified by the cocoon layers (i.e., inner, middle, or outer) from which they originated. This report details the biological properties and the cellular responses of the three silk layers. The different cocoon layers were compared for their bone regeneration capabilities in vivo. The porosity of the silk nets increased from the inner layer to the outer layer when all of the membranes were compared using scanning electron microscopy (SEM). A difference in spectral intensity was observed in the Fourier transform infrared (FT-IR) spectra, indicating different amino acid compositions in these layers. An amino acid composition test demonstrated that the serine content decreased from the outer layer to the inner layer. Characterization of the protein release from each net demonstrated that the highest amount of protein release was observed in the inner layer group. The middle layer showed higher alkaline phosphatase (ALP) activity than the other layers in cellular experiments. Animal experiments indicated that the middle layers exhibit the highest bone volume 8 weeks post-operation (p<0.05). The membranes obtained directly from the thin middle layer of silk cocoons without any regeneration protocol have the potential to be used as an eco-friendly bone regeneration material for in vivo applications.

Directional moisture transfer through a wild silkworm cocoon wall.

A silkworm cocoon is a porous biological structure with multiple protective functions. In the current work, the authors have used both experimental and numerical methods to reveal the unique moisture transfer characteristics through a wild Antheraea pernyi silkworm cocoon wall, in comparison with the long-domesticated Bombyx mori silkworm cocoon walls. The water vapor transmission and water vapor permeability (WVP) properties show that the A. pernyi cocoons exhibit directional moisture transfer behavior, with easier moisture transfer from inside out than outside in [e.g., the average WVP is 0.057 g/(h m bar) from inside out and is 0.034 g/(h m bar) from outside in]. Numerical analysis shows that the cubic mineral crystals in the outer section of the A. pernyi cocoon wall create a rough surface that facilitates air turbulence and promotes disturbance amplitude of the flow field, leading to lengthened water vapor transfer path and increased tortuosity of the moist air. It also indicates the vortex of water vapor can be generated in the outer section of cocoon wall, which increases the diffusion distance of water vapor and enhances the turbulence kinetic energy and turbulence eddy dissipation, signifying higher moisture resistance in the outer section. The difference in moisture resistance of the multiple A. pernyi cocoon layers is largely responsible for the unique directional moisture transfer behavior of this wild silkworm cocoon. These findings may inspire a biomimicry approach to develop novel lightweight moisture management materials and structures.