Emission characteristics and probabilistic health risk of volatile organic compounds from leather sofa.

Furniture is identified as a vital volatile organic compound (VOC) emission source in the indoor environment. Leather has become the most common raw and auxiliary fabric material for upholstered furniture, particularly with extensive consumption in sofas, due to its abundant resources and efficient functions. Despite being widely traded across the world, little research has been conducted on the VOCs released by leather materials and their health risk assessment in the indoor environment. Accordingly, this study investigated the VOC emissions of leather with different grades and the health risk of the inhalation exposure. Based on the ultra-fast gas phase electronic nose (EN) and GC-FID/Qtof, the substantial emissions of aliphatic aldehyde ketones (Aks), particularly hexanal, appear to be the cause of off-flavor in medium and low grade (MG and LG) sofa leathers. The health risk assessment indicated that leather materials barely pose non-carcinogenic and carcinogenic effects to residents. Given the abundance of VOC sources and the accumulation of health risks in the indoor environment, more stringent specifications concerning qualitative and quantitative content should be extended to provide VOC treatment basic for the manufacturing industry and obtain better indoor air quality.

Space-Efficient 3D Microalgae Farming with Optimized Resource Utilization for Regenerative Food.

Photosynthetic microalgae produce valuable metabolites and are a source of sustainable food that supports life without compromising arable land. However, the light self-shading, excessive water supply, and insufficient space utilization in microalgae farming have limited its potential in the inland areas most in need of regenerative food solutions. Herein, this work develops a 3D polysaccharide-based hydrogel scaffold for vertically farming microalgae without needing liquid media. This liquid-free strategy is compatible with diverse microalgal species and enables the design of living microalgal frameworks with customizable architectures that enhance light and water utilization. This approach significantly increases microalgae yield per unit water consumption, with an 8.8-fold increase compared to traditional methods. Furthermore, the dehydrated hydrogels demonstrate a reduced size and weight (≈70% reduction), but readily recover their vitality upon rehydration. Importantly, valuable natural products can be produced in this system including proteins, carbohydrates, lipids, and carotenoids. This study streamlines microalgae regenerative farming for low-carbon biomanufacturing by minimizing light self-shading, relieving water supply, and reducing physical footprints, and democratizing access to efficient aquatic food production.

A novel complex coupling agent for enhancing the compatibility between collagen fiber and natural rubber: A utilization strategy for leather wastes.

Leather shavings are generated as solid waste in the leather industry and may cause environmental pollution if not disposed judiciously. These solid wastes, primarily composed of collagen fibers (CFs), can be recycled as biomass composites. However, CFs are incompatible with natural rubber (NR) due to its hydrophilicity. Conventionally, the compatibility has been improved by utilizing silane coupling agents (SCAs) along with a large number of organic solvents, which further contribute to environmental pollution. In this study, we developed a novel complex coupling agent (CCA) to enhance the compatibility between CF and NR. The CCA was synthesized through a coordination reaction between Cr(III) and α-methacrylic acid (MAA). Cr(III) in the coupling agent coordinates with the active groups in CFs, while the unsaturated double bonds in MAA facilitate covalent crosslinking between the CCA and NR, improving compatibility. The coordination bonding between CF and NR exhibits strong interfacial interaction, endowing the composites with desirable mechanical properties. Moreover, the proposed method is an economical and green approach that can be used to synthesize CF-based composites without requiring organic solvents. Herein, a strategy promoted sustainable development in the leather industry has been established.

High temperature inhibits photosynthesis of chrysanthemum (Chrysanthemum morifolium Ramat.) seedlings more than relative humidity.

High relative humidity (RH) and high temperature are expected more frequently due to climate change, and can severely affect the growth of chrysanthemums. In order to analyze the interactive effects of RH and high temperature on the photosynthetic performance of chrysanthemum, a completely randomized block experiment was conducted with three factors, namely temperature (Day/night temperature, 35°C/18°C, 38°C/18°C, 41°C/18°C), RH (Whole day RH, 50%, 70%, 90%), and treatment duration (3d, 6d, 9d). The control (CK) temperature was 28°C/18°C and RH was 50%. The results showed that with the increase of temperature, the apparent quantum efficiency (AQE), maximum net photosynthetic rate (Pn-max), net photosynthetic rate (Pn), transpiration rate (Tr), water use efficiency (WUE), maximal recorded fluorescence intensity (Fm), PSII maximal photochemical efficiency (Fv/Fm), absorption flux per cross section (ABS/CSm), trapped energy flux per cross section (TRo/CSm), electron transport flux per cross section (ETo/CSm) and photosynthetic pigment content of leaves significantly decreased, the minimal recorded fluorescence intensity (Fo), fluorescence intensity at point J of the OJIP curve (Fj) and non-photochemical quenching per cross section (DIo/CSm) significantly increased, the fluorescence difference kinetics of the OJ phase of chrysanthemum leaves showed K-bands. Pn, AQE, Fm, Fv, Fv/Fm, ABS/CSm, TRo/CSm, ETo/CSm and photosynthetic pigment content were higher at 70% RH than the other two RH conditions. The dominant factor causing the decrease of Pn in leaves was stomatal limitation at 35°C,38°C, three RH conditions, 3d and 6d, but non-stomatal limitation at 41°C and 9d. There was an interaction between temperature and RH, with a significant impact on Pn. The temperature had the greatest impact on Pn, followed by RH. This study confirms that heat stress severely affects the photosynthesis of chrysanthemum leaves, and when the temperature reaches or exceeds 35°C, adjusting the RH to 70% can effectively reduce the impact of heat stress on chrysanthemum photosynthesis.

Effects of different factors on the friction and wear mechanical properties of titanium alloy materials with cortical bones at near service conditions.

The artificial joint is one of the most effective methods to treat joint injuries. The service performance of artificial joints is gradually weakened because of the wear of artificial joints in actual service. In order to obtain the potential failure mechanism of the artificial joint in actual service, the study was carried out with the multiple factors that affect the service performance of the artificial joint. The experimental study was carried out on the change rule of mechanical behavior of the contact interface between the artificial joint of titanium alloy and cortical bone. The multi-factor is compression load, contact load, friction velocity, and lubrication environment, respectively. The results indicate that the friction coefficient, wear mass, and wear coefficient of Ti-6A1-4V titanium alloy decreased with the increasing of the compression load. The friction rate and the friction coefficient of Ti-6A1-4V titanium alloy decreased with the increasing of the contact load. The wear mass and friction coefficient of Ti-6A1-4V titanium alloy increased with the increasing of contact load. The lubrication effect is better with the increasing of lubricant concentration. Based on the observation of the SEM, the wear type influenced by compression load and friction rate is mainly abrasive wear and oxidation wear. The wear type influenced by contact load is mainly abrasive wear and adhesive wear. The wear type influenced by lubricants is mainly oxidation wear. When wear mass and wear coefficient are used as the criteria for evaluating friction and wear, the order of influential factors to friction and wear of Ti-6Al-4V titanium alloy plate is friction rate, compression load, contact load, and lubricant concentration. This research can provide a theoretical reference for the optimal manufacture of the artificial joint of titanium alloy and optimal rules of safe service conditions.

Structure and mechanical properties of ladybird elytra as biological sandwich panels.

The armour of the ladybird, elytra, protect the body from injury and are well-adapted to flight. However, experimental methods to decipher their mechanical performances had been challenging due to the small size, making it unclear how the elytra balance mass and strength. Here, we provide insights to the relationship between the microstructure and multifunctional properties of the elytra by means of structural characterization, mechanical analysis and finite element simulations. Micromorphology analysis on the elytron revealed the thickness ratio of the upper lamination, middle layer and lower lamination is approximately 51:139:7. The upper lamination had multiple cross fibre layers and the thickness of each fibre layer is not the same. In addition, the tensile strength, elastic modulus, fracture strain, bending stiffness and hardness of elytra were obtained through in-situ tensile and nanoindentation-bending under the influence of multiple loading conditions, which also serve as references for finite element models. The finite element model revealed that structural factors such as thickness of each layer, angle of fibre layer and trabeculae are key to affecting the mechanical properties, but the effect is different. When the thickness of upper, middle and lower layers is the same, the tensile strength provided by unit mass of the model is 52.78% lower than that provided by elytra. These findings broaden the relationship between the structural and mechanical properties of the ladybird elytra, and are expected to inspire the development of sandwich structures in biomedical engineering.

Trade-off effect of dissolved organic matter on degradation and transformation of micropollutants: A review in water decontamination.

The degradation of micropollutants by various treatments is commonly affected by the ubiquitous dissolved organic matter (DOM) in the water environment. To optimize the operating conditions and decomposition efficiency, it is necessary to consider the impacts of DOM. DOM exhibits varied behaviors in diverse treatments, including permanganate oxidation, solar/ultraviolet photolysis, advanced oxidation processes, advanced reduction process, and enzyme biological treatments. Besides, the different sources (i.e., terrestrial and aquatic, etc) of DOM, and operational circumstances (i.e., concentration and pH) fluctuate different transformation efficiency of micropollutants in water. However, so far, systematic explanations and summaries of relevant research and mechanism are rare. This paper reviewed the "trade-off" performances and the corresponding mechanisms of DOM in the elimination of micropollutants, and summarized the similarities and differences for the dual roles of DOM in each of the aforementioned treatments. Inhibition mechanisms typically include radical scavenging, UV attenuation, competition effect, enzyme inactivation, reaction between DOM and micropollutants, and intermediates reduction. Facilitation mechanisms include the generation of reactive species, complexation/stabilization, cross-coupling with pollutants, and electron shuttle. Moreover, electron-drawing groups (i.e., quinones, ketones functional groups) and electron-supplying groups (i.e., phenols) in the DOM are the main contributors to its trade-off effect.

Chrome shaving-derived biochar as efficient persulfate activator: Ti-induced charge distribution modulation for 1O2 dominated nonradical process.

Efficient degradation of organic contaminants by oxidative radicals remains a challenge due to invalid consumption of radicals and easy generation of secondary halogenated pollutants. In this work, an efficient and recyclable bimetallic biochar (Cr-Ti/BC) was developed through peroxydisulfate (PDS) activation via nonradical pathway for sulfamethoxazole (SMX) degradation. The Cr-Ti/BC exhibited excellent catalytic activity for 99.9 % of SMX removal with a high kobs of 0.13 min-1, and negligible inhibitory effects were observed under various pH condition. The activation mechanisms were (i) metastable reactive intermediates (Cr-Ti/BC-PDS) formation via an interaction between Cr-Ti/BC and PDS on the active defective sites (e.g., OH/COC, COOH, CO, nitric oxides, graphitic N, and pyridinic N), and (ii) 1O2 generation through electron transfer between Cr-Ti/BC-PDS intermediates and dissolved oxygen. The high reusability and strong stability of Cr-Ti/BC also verified the outstanding advantage of the Cr-Ti/BC during practical application. This study not only is the first study the catalytic performance of Cr and Ti co-doped biochar for PDS activation, but also successfully provides a promising strategy to induce a nonradical pathway for PDS activation, which is of great significance for the subsequent method design, and thus paving the path for exploiting advanced oxidation systems in practical application for organic contaminant removal toward polluted site remediation.

Resource utilization of tannery sludge to prepare biochar as persulfate activators for highly efficient degradation of tetracycline.

In this work, a low-cost carbon-based catalyst (TSBC) was prepared by the facile one-pot pyrolysis of tannery sludge (TS) and used to activate persulfate (PS) for tetracycline (TC) removal. The results showed that TSBC-500 exhibited optimal physicochemical properties and the best performance for PS activation to remove TC from drinking water. Approximately 99.1% of TC was removed in the TSBC-500/PS system, which was considerably higher than those in the TSBC-500 adsorption and pure PS systems. Radical quenching experiments indicated that •OH and SO4•- played major roles in the TC removal in the TSBC-500/PS system. In addition, transition metals, functional groups, and the high degree of carbon structural defects were beneficial for PS activation to degrade TC. This study not only newly contributes to high-value utilization of TS as a PS activator but also offers an efficient method for the removal of organic pollutants.

Genome-wide identification, characterization, evolution, and expression pattern analyses of the typical thioredoxin gene family in wheat (Triticum aestivum L.).

Typical thioredoxin (TRX) plays an important role in maintaining redox balance in plants. However, the typical TRX genes in wheat still need to be comprehensively and deeply studied. In this research, a total of 48 typical TaTRX genes belonging to eight subtypes were identified via a genome-wide search in wheat, and the gene structures, protein conserved motifs, and protein 3D structures of the same subtype were very similar. Evolutionary analysis showed that there are two pairs of tandem duplication genes and 14 clusters of segmental duplication genes in typical TaTRX family members; TaTRX15, TaTRX36, and TaTRX42 had positive selection compared with the orthologs of their ancestral species; rice and maize have 11 and 13 orthologous typical TRXs with wheat, respectively. Gene Ontology (GO) analysis indicated that typical TaTRXs were involved in maintaining redox homeostasis in wheat cells. Estimation of ROS content, determination of antioxidant enzyme activity, and gene expression analysis in a line overexpressing one typical TaTRX confirmed that TRX plays an important role in maintaining redox balance in wheat. A predictive analysis of cis-acting elements in the promoter region showed that typical TaTRXs were extensively involved in various hormone metabolism and response processes to stress. The results predicted using public databases or verified using RT-qPCR show that typical TaTRXs were able to respond to biotic and abiotic stresses, and their expression in wheat was spatiotemporal. A total of 16 wheat proteins belonging to four different families interacting with typical TaTRXs were predicted. The above comprehensive analysis of typical TaTRX genes can enrich our understanding of this gene family in wheat and provide valuable insights for further gene function research.

Study on the structural features and geometric parameters affecting the axial mechanical properties of the primary feather rachis.

The seagull feather shaft is an important part of the feather, which provides a good mechanical support for the excellent flight performance of seagull, and has the characteristics of lightweight and high strength. In this paper, the microstructure of the seagull feather rachis was observed firstly. Then, based on the structure of feather rachis, combined with the cortex that plays the main load-bearing role, a model with the characteristics of the cortex was proposed and its finite element model was established. Through analyzing the simulation, the effect of section shape of cortex on mechanical properties of feathers under axial impact was revealed. And the conclusion that the section shape with groove structure and non-equal wall thickness could have different effects on mechanical properties was drawn. Then, parameterized cortical models were studied, including different impact velocities and different cortical heights, to reveal the differences in mechanical properties of cortical models.

High mass load of oxygen-enriched microporous hollow carbon spheres as electrode for supercapacitor with solar charging station application.

Carbon materials modified with pores and heteroatoms have been pursued as promising electrode for supercapacitors due to the synergic storage of electric double-layer capacitance (EDLC) and pseudocapacitance. A vital problem that the actual effect of pores and heteroatoms on energy storage varies with the carbon matrix used presents in numerous carbon electrodes, but is ignored greatly, which limits their sufficient utilization. Moreover, most of modified carbon electrodes still suffer from severe capacitance degeneration under high mass load caused by the blocked surface and inaccessible bulk phase. Here, we shape an interconnected hollow carbon sphere (HCS) as the matrix by regulating and selectively-etching low molecular weight component in the inhomogeneous precursors, accompanied with the decoration of rich oxygen groups (15.9at%) and micropores (centering at 0.6-1.4 nm). Finite-element calculation and energy storage kinetics reveal the modified HCS electrode exposes accessible dual active surface with highly-matched electrons and ions for pores and oxygen groups to improve both EDLC and pseudocapacitance. Under a commercial-level load of 11.2 mg cm-2, the HCS exhibits a high specific capacitance of 288.3 F g-1 at 0.5 A g-1, performing a retention of 91.8% relative to 314 F g-1 under 2.8 mg cm-2 load, applicable for solar charging station to efficiently drive portable electronics.

A Wheat TaTOE1-B1 Transcript TaTOE1-B1-3 Can Delay the Flowering Time of Transgenic Arabidopsis.

Flowering time is one of the most important agronomic traits in wheat production. A proper flowering time might contribute to the reduction or avoidance of biotic and abiotic stresses, adjust plant architecture, and affect the yield and quality of grain. In this study, TaTOE1-B1 in wheat produced three transcripts (TaTOE1-B1-1, TaTOE1-B1-2, and TaTOE1-B1-3) by alternative splicing. Compared to the longest transcript, TaTOE1-B1-1, TaTOE1-B1-3 has a deletion in the sixth exon (1219-1264 bp). Under long-day conditions, the heterologous overexpression of the TaTOE1-B1-3 gene delayed flowering, prolonged the vegetative growth time, and enlarged the vegetative body of Arabidopsis, but that of TaTOE1-B1-1 did not. As typical AP2 family members, TaTOE1-B1-1 and TaTOE1-B1-3 are mainly located in the nucleus and have transcriptional activation activities; the transcriptional activation region of TaTOE1-B1-3 is located in the C-terminal. In TaTOE1-B1-3 overexpression lines, the expression of flowering-related AtFT and AtSOC1 genes is significantly downregulated. In addition, this study confirms the protein-protein interaction between TaTOE1-B1-3 and TaPIFI, which may play an important role in flowering inhibition. These results provide a theoretical basis for the precise regulation of wheat flowering time.

Nucleoredoxin Gene TaNRX1 Positively Regulates Drought Tolerance in Transgenic Wheat (Triticum aestivum L.).

Drought is the main abiotic stress factor limiting the growth and yield of wheat (Triticum aestivum L.). Therefore, improving wheat tolerance to drought stress is essential for maintaining yield. Previous studies have reported on the important role of TaNRX1 in conferring drought stress tolerance. Therefore, to elucidate the regulation mechanism by which TaNRX1 confers drought resistance in wheat, we generated TaNRX1 overexpression (OE) and RNA interference (RNAi) wheat lines. The results showed that the tolerance of the OE lines to drought stress were significantly enhanced. The survival rate, leaf chlorophyll, proline, soluble sugar content, and activities of the antioxidant enzymes (catalase, superoxide dismutase, and peroxidase) of the OE lines were higher than those of the wild type (WT); however, the relative electrical conductivity and malondialdehyde, hydrogen peroxide, and superoxide anion levels of the OE lines were lower than those of the WT; the RNAi lines showed the opposite results. RNA-seq results showed that the common differentially expressed genes of TaNRX1 OE and RNAi lines, before and after drought stress, were mainly distributed in the plant-pathogen interaction, plant hormone signal transduction, phenylpropane biosynthesis, starch and sucrose metabolism, and carbon metabolism pathways and were related to the transcription factors, including WRKY, MYB, and bHLH families. This study suggests that TaNRX1 positively regulates drought stress tolerance in wheat.

Conversion of tannery solid waste to an adsorbent for high-efficiency dye removal from tannery wastewater: A road to circular utilization.

The high value-added use of tannery solid waste and elimination of tannery liquid waste in the leather-making industry have attracted widespread attention. In this study, a MgO-doped biochar (MgO/BC) adsorbent was successfully prepared by utilizing tannery solid waste (i.e., non-tanned hide wastes) as the biomass material for dye removal from tannery wastewater. Characterization results indicated that MgO was uniformly embedded into the porous BC structure. The adsorption capacity of acid orange II by MgO/BC reached up to 448.4 mg g-1, which drastically exceeded the pure BC and other reported adsorbents. The adsorption behavior of acid orange II by MgO/BC matched nicely with Langmuir isotherm and pseudo-second-order kinetic model. This satisfactory adsorption capacity of MgO/BC for acid orange II was mainly due to the large specific surface area and the enhanced electrostatic interaction. According to the BET, zeta potential and XPS analysis, the possible mechanism towards acid orange II removal was attributed to the pore filling, surface complexation, electrostatic attraction and π-π interaction. In addition, MgO/BC showed the efficient removal towards anionic dyes from actual tannery wastewater. This work could provide guidance for the value-added utilization of tannery solid waste and a practical way to remove dyes from tannery wastewater.

Mechanical properties and failure deformation mechanisms of yak horn under quasi-static compression and dynamic impact.

In the natural environment, the horns of yak possess remarkable structural mechanical properties to protect the head from injury. In this paper, quasi-static compression and dynamic impact tests were conducted on yak horn in different regions under axial and lateral conditions to evaluate mechanical properties such as elastic modulus, ultimate strength and energy absorption. Meanwhile, the failure deformation mechanism under both low and high strain rates is explored. Moreover, experimental analysis of the correlation among mechanical properties, sampling position, strain rate and loading direction was conducted. Fracture surface of horn was observed with the scanning electron microscope (SEM). Research data demonstrate that specific energy absorption and mechanical properties are correlated with sampling position. Under quasi-static compression and dynamic impact, clear anisotropy behavior of horn was observed, which is evidently reflected in the load-displacement curve. Mechanical properties such as elastic modulus and ultimate strength are different under quasi-static compression and dynamic impact. The failure mode of lamellar buckling and delamination existed in the axial failure process. Brittle fracture and extrusion densification occurred more frequently in the process of lateral failure.

Highly efficient removal of Cr(III)-poly(acrylic acid) complex by coprecipitation with polyvalent metal ions: Performance, mechanism, and validation.

The Cr(III)-organic complexes formed between Cr(III) and multifunctional group ligands, such as polyacrylate, are highly water soluble and difficult to be removed from wastewater by common treatments. A novel strategy for efficiently removing Cr(III)-poly (acrylic acid) complex (Cr(III)-PAA) from wastewater without introducing secondary pollution is proposed using a coprecipitation method with polyvalent metal ions. Al(III), Fe(III), Zr(IV), and Ti(IV) were combined with the carboxyl of Cr(III)-PAA to decrease hydrophilia and achieve fast and efficient coprecipitation. Cr(III)-PAA was efficiently removed from wastewater by using these polyvalent metal ions, especially at low pH, where the ions exist as monomer. The residual concentration of Cr(III) in treated wastewater under the optimized experimental condition was less than 1.0 mg/L. No Cr(VI) and negligible amount of polyvalent metal ions were detected in the treated wastewater, indicating that almost all of the ions coprecipitated with Cr(III)-PAA. No secondary pollution also occurred. The high reactivity between the polyvalent metal ions and Cr(III)-PAA and the sharp decrease in the hydrophilia of the complex contributed to its highly efficient removal from wastewater. Actual tannery wastewater containing Cr(III)-organic complexes with high solubility and stability was treated through coprecipitation with Al(III). A high Cr(III) removal efficiency of 99.0% was obtained. This work provides new insights into the removal of soluble Cr(III)-organic complexes from wastewater by using an environment-friendly and cost-effective method.

Novel Fe3O4-poly(methacryloxyethyltrimethyl ammonium chloride) adsorbent for the ultrafast and efficient removal of anionic dyes.

The removal of anionic dyes from wastewater has attracted global concern. In this work, a novel Fe3O4-poly(methacryloxyethyltrimethyl ammonium chloride) (Fe3O4-pDMC) adsorbent for the efficient removal of anionic dyes from wastewater was successfully synthesized by grafting methacryloxyethyltrimethyl ammonium chloride (DMC) on the surfaces of Fe3O4. Various characterization analyses confirmed that the obtained Fe3O4-pDMC possessed numerous functional groups on its surfaces and retained good magnetic separation properties. Fe3O4-pDMC showed ultrafast removal for acid orange 7 (AO7, 58.6%, 1 min) and direct blue 15 (DB15, 98.1%, 1 min), and the maximum adsorption capacity was high (266.8 and 336.5 mg g-1 for AO7 and DB15, respectively). In addition, the adsorption process was in accordance with pseudo-second-order kinetics and the Langmuir isotherm. The mechanism underlying the adsorption of Fe3O4-pDMC on anionic dyes was mainly dependent on electrostatic interaction. This study illustrated that Fe3O4-pDMC has great potential applications as an environmentally friendly, desirable adsorbent for the efficient removal of anionic dyes from wastewater.

Microstructure and compression resistance of bean goose (Anser fabalis) feather shaft.

The bean goose Anser fabalis, noted for its excellent flying ability, has feathers composed of keratinized products derived from epidermal cells, which play a crucial role in flight. The feather shaft is an important connective unit, made of a lightweight material, which also contributes to aiding flight. The shaft can withstand loads from different directions and has outstanding compression resistance. In this study, the microstructure and composition of the A. fabalis feather shaft were observed by scanning electron microscopy and Fourier transform infrared spectrometry, and its compression resistance was studied by compression testing. The results indicated that the mechanical property of the shaft is related to its microstructure. Compression testing verified that the primary feathers had the strongest mechanical properties, followed by the secondaries, and finally the alulae. Under the same conditions, the specific energy absorption of the three feather types was 5.96, 5.02, and 3.17 J/g, respectively. With increasing moisture content, the rachis was softened and the energy absorption was reduced. At low moisture content, the specific energy absorption of the primaries was reduced to 1.03 J/g, that of the secondaries was reduced to 1.72 J/g, and that of the alulae to 0.39 J/g. The feather shafts have the advantage of light weight while maintaining the required mechanical properties. These results provide a theoretical and experimental basis for crashworthiness in bionic designs based on the requirements of light weight.