Search Results (262)

Natural latex harvest is pushing the boundaries of unmanned agricultural production in rubber milk collection via integrated robots in hilly and mountainous regions, such as the fixed and mobile tapping robots widely deployed in forests. As there are bad working conditions and complex natural environments surrounding rubber trees, the real-time and precision assessment of rubber milk yield status has emerged as a key requirement for improving the efficiency and autonomous management of these kinds of large-scale automatic tapping robots. However, traditional manual rubber milk yield status detection methods are limited in their ability to operate effectively under conditions involving complex terrain, dense forest backgrounds, irregular surface geometries of rubber milk, and the frequent occlusion of rubber milk bowls (RMBs) by vegetation. To address this issue, this study presents an unmanned aerial vehicle (UAV) imagery rubber milk yield state detection method, termed YOLOv8n-RMB, in unstructured field environments instead of manual watching. The proposed method improved the original YOLOv8n by integrating structural enhancements across the backbone, neck, and head components of the network. First, a receptive field attention convolution (RFACONV) module is embedded within the backbone to improve the model’s ability to extract target-relevant features in visually complex environments. Second, within the neck structure, a bidirectional feature pyramid network (BiFPN) is applied to strengthen the fusion of features across multiple spatial scales. Third, in the head, a content-aware dynamic upsampling module of DySample is adopted to enhance the reconstruction of spatial details and the preservation of object boundaries. Finally, the detection framework is integrated with the BoT-SORT tracking algorithm to achieve continuous multi-object association and dynamic state monitoring based on the filling status of RMBs. Experimental evaluation shows that the proposed YOLOv8n-RMB model achieves an AP@0.5 of 94.9%, an AP@0.5:0.95 of 89.7%, a precision of 91.3%, and a recall of 91.9%. Moreover, the performance improves by 2.7%, 2.9%, 3.9%, and 9.7%, compared with the original YOLOv8n. Plus, the total number of parameters is kept within 3.0 million, and the computational cost is limited to 8.3 GFLOPs. This model meets the requirements of yield assessment tasks by conducting computations in resource-limited environments for both fixed and mobile tapping robots in rubber plantations. Full article

Taraxacum kok-saghyz Rodin, an important rubber-producing plant, has emerged as a potential alternative crop for the natural rubber industry. Geranyl diphosphate synthase (GDS) catalyzes the condensation of dimethylallyl pyrophosphate and isopentenyl pyrophosphate into geranyl pyrophosphate in the mevalonate pathway in plants. However, its specific functions in natural rubber biosynthesis in T. kok-saghyz remain unclear. Methods: We conducted genome-wide analyses of TkGDS genes, followed by transient transformation assay, expression profiling, natural rubber quantification, and analysis of T. kok-saghyz photosynthesis. Results: Seven TkGDS genes are located on chromosomes A6 and A7 with an uneven distribution. All encoded TkGDS proteins contain FARM and SARM motifs. TkGDS1, TkGDS2, and TkGDS7 possess lspA domains, while TkGDS3, TkGDS4, TkGDS5, and TkGDS6 contain PLN02890 domains; both subgroups share similar domain architecture. TkGDS1, TkGDS2, and TkGDS7 exhibit interspecies collinearity with Arabidopsis thaliana; no intraspecies collinearity was detected. The putative cis-acting elements in promoter region of TkGDS genes mainly comprised abscisic acid responsiveness, anaerobic induction, light responsiveness, and MeJA responsiveness. Transient expression assays confirmed chloroplast localization of all TkGDS proteins. A strong positive correlation was observed between TkGDS1/TkGDS7 expression and natural rubber content, as confirmed by both transcriptome and qPCR analyses in T. kok-saghyz lines. Furthermore, overexpression of TkGDS1 and TkGDS7 improved photosynthetic efficiency and significantly increased natural rubber content (OE-TkGDS1: 6.08 ± 0.16%; OE-TkGDS7: 5.62 ± 0.32%; WT: 4.76 ± 0.28%). Conclusions: Our study elucidates the role of GDS1 and GDS7 in promoting growth and latex content, offering a genetic strategy for enhancing rubber accumulation in T. kok-saghyz. Full article

The majority of downhole monitoring methods currently available for well cement projects, which are used to assess the quality of cement placement and monitor well integrity over time, are primarily qualitative in nature and rely on surface signs. Obviously, there is a need for a practical quantitative downhole monitoring method to ensure proper cement placement and long-term performance. One potential resolution to address this enduring problem would involve enhancing the designs of the cement slurry and transforming the cement into durable downhole logging equipment, thereby facilitating real-time observation of operations. To address this issue, in this work, carboxylated styrene butadiene rubber (XSBR) polymer-treated cement was used to understand the gas migration and fluid loss mechanism. The experimental findings indicate that the electrical resistivity of polymer-treated cement is significantly influenced by applied loads and stresses. The unconfined compressive strength test with XSBR-blended cement showed a significant improvement from 22.5 MPa to 33.31 MPa when XSBR increased from 0% to 3%. Additionally, in the high pressure and high temperature (HPHT) chamber, the latex polymer used as a migration additive control, the total fluid loss is found to be about 59.2 mL under 30 min of testing. Also, to emulate the accuracy, nonlinear predictive models based on the resistivity index correlation were developed to forecast polymer-treated cement performance for all the tests performed in this study. Hence, the utilization of polymer-treated cement systems proves to be a valuable method for monitoring the placement and post-placement performance of cement, as well as for visualizing real-time operational issues associated with cementing. This will also allow operators to provide immediate solutions, saving time and operational costs. Full article

Tapping panel dryness (TPD) and tapping panel necrosis (TPN) are syndromes that reduce the yield of rubber trees. Their causes are associated with factors such as clone type, tapping system, and environmental stress and are potentially linked to nutrient deficiencies. This study aimed to investigate the causes of these disorders, with particular focus on their relationship with nutrient fluctuations in plant tissues. The experiment was conducted at rubber plantations owned by local farmers in Pakkhat District, Bueng Kan Province, Thailand, where soil fertility is generally poor. The plantations were 14–16 years old and had been tapped for 7–9 years. Two rubber tree clones (RRIM600 and RRIT251) were used to evaluate three different tree types: healthy, TPD-affected, and TPN-affected. For each clone, five plantations were sampled. The measurements included the incidence of abnormalities; trunk girth; yield; and nutrient concentrations in the soil, top shoot, bark, and latex. The nutrient analysis focused on nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and boron (B). The results showed that the incidence of abnormalities (both TPD and TPN) was higher in clone RRIT251 than in RRIM600. Yield was reduced in trees affected by TPD and was dramatically reduced in those affected by TPN. In RRIT251 trees affected by TPD, the lowest concentrations of K, Ca, and B were found in the bark, along with the lowest Ca concentration in the top shoot. These findings indicate that RRIT251 is more susceptible to bark necrosis than RRIM600 and that reductions in K, Ca, and B may be associated with development of the syndromes. Full article

To address the inherent trade-off between high wet friction and poor mechanical properties in carboxylated nitrile butadiene rubber (XNBR) films, this study introduces a layered silicate (bentonite) as a dual-functional lubricating-reinforcing additive. Unlike the conventional linear polymer anionic polyacrylamide (APAM), which has limited efficacy, bentonite exhibits superior performance attributed to its unique two-dimensional (2D) nanosheet structure. The mechanism is twofold: under shear stress, the hydrated nanosheets align to form a highly efficient, low-friction interface; simultaneously, these rigid nanosheets act as a reinforcing filler within the matrix, enhancing mechanical strength through stress dissipation and microcrack inhibition. Consequently, the bulk incorporation of bentonite resulted in a remarkable 38% increase in tensile strength, coupled with a significant 48% reduction in the wet coefficient of friction. This work elucidates an effective mechanism for synergistically improving both surface and bulk properties of a polymer using inorganic nanosheets, offering a new strategy for the design of advanced functional composites. Full article

The purpose of this study was to establish the relationship between the chilling resistance of rubber trees and the bark-bleeding characteristics caused by chilling stress, considering physiological indicators in rubber tree bark, cell wall chemical components, fiber morphologies, and tensile properties. This offered a unique perspective for examining the underlying mechanisms of latex bleeding and chilling stress in Hevea brasiliensis. One-year-old seedlings and two-year-old twig segments in five- and twenty-one-year-old rubber trees (5YB and 21YB) were used to compare the age-mediation differences in their various parameters. Meanwhile, the LT₅₀ values were calculated with Logistic regression analysis of relative electrical conductivity (REC) data under gradient low temperatures. Subsequently, changes in corresponding parameters of 1-year-old seedling stem bark at different ages were determined, and the bark-bleeding characteristics of seedlings and twig segments were analyzed under artificially simulated chilling stress, respectively. A correlation analysis between semi-lethal temperature (LT₅₀) values, relative water content (RWC) values, bark-bleeding characteristics, cell-wall chemical component contents, fiber dimensions, and tensile property parameters was implemented to estimate interrelationships among them. The LT₅₀ values ranged from −2.0387 °C to −0.8695 °C. The results showed that the chilling resistance order of rubber trees at different ages was as follows: 21YB (2-year-old twig bark from 21-year-old rubber trees) > 5YB (2-year-old twig bark from 5-year-old rubber trees) > SLB (semi-lignification bark in 1-year-old seedlings) > GB (green bark in 1-year-old seedlings). The chilling resistance of seedlings and twig segments in rubber trees was highly positively (p < 0.001) related to fiber morphologies. Chilling-induced bark-bleeding characteristics were significantly correlated (p < 0.001) with fiber morphologies, bark tensile properties, and cell-wall components. The analysis data in this study contribute towards building a comprehensive understanding of the mechanisms of chilling-induced bark bleeding needed not only in rubber tree cultivation but also in sustainable rubber production. Full article

By proportionally blending fresh latex from PR107, Reyan 72059, and Reyan 73397, and employing both acid- and enzyme-assisted microbial coagulation methods, this study analyzed the effects of the specific latex formulation on the following: physicochemical properties, non-rubber components, molecular weight and distribution, vulcanization characteristics of compounded rubber, and physical–mechanical properties of vulcanized natural rubber. The results indicate that, compared to acid-coagulated natural rubber, enzyme-assisted microbial coagulated natural rubber exhibits slightly lower levels of volatile matter, impurities, plasticity retention index (PRI), nitrogen content, calcium ions (Ca²⁺), iron ions (Fe³⁺), and fatty acid content. Conversely, it demonstrates higher values in ash content, initial plasticity (P₀), Mooney viscosity (M_L(1+4)), acetone extract, magnesium ions (Mg²⁺), copper ions (Cu²⁺), manganese ions (Mn²⁺), gel content, molecular weight and distribution, and glass transition temperature (Tg). With the increase in the proportion of PR107 and Reyan 72059 fresh latex, the ash content, volatile matter content, fatty acid content, gel content, and dispersion coefficient (PDI) of natural rubber gradually decrease, while the impurity content, PRI, nitrogen content, weight-average molecular weight (Mw), and number-average molecular weight (Mn) gradually increase. Compared to acid-coagulated natural rubber compounds, enzyme-assisted microbial-coagulated natural rubber compounds exhibit higher minimum torque (M_L) and maximum torque (M_H), but shorter scorch time (t₁₀) and optimum cure time (t₉₀). Furthermore, as the proportion of PR107 and Reyan 72059 fresh latex increases, the ML of the compounds gradually decreases. In pure rubber formulations, enzyme-assisted microbial-coagulated natural rubber vulcanizates demonstrate higher tensile strength, tear strength, modulus at 300%, and Shore A hardness compared to acid-coagulated natural rubber vulcanizates. When the fresh latex ratio of PR107, Reyan 72059, and Reyan 73397 is 1:1:3, the tensile strength and 300% modulus of the natural rubber vulcanizates reach their maximum values. In carbon black formulations, the tensile strength and tear strength of enzyme-assisted microbial-coagulated natural rubber vulcanizates are significantly higher than those of acid-coagulated natural rubber vulcanizates in pure rubber formulations, with the increase exceeding that of other samples. Full article

Partial organic substitution (POS) is a promising strategy to enhance soil fertility and agricultural sustainability. However, the mechanisms by which varying organic substitution ratios affect soil quality and latex yields in rubber plantations remain unclear. We conducted a two-year field experiment in a rubber plantation with six treatments: no fertilizer (CK), 100% synthetic fertilizer (NPK), and synthetic nitrogen fertilizer substituted with 25% (25 M), 50% (50 M), 75% (75 M), and 100% (100 M) manure. The results indicated that POS treatments significantly increased pH, soil organic carbon (SOC), total phosphorus (TP), total nitrogen (TN), NH₄⁺-N, enzyme activity, and leaf nutrient (C, N, and P) content compared to NPK. Compared with NPK, the soil quality (evaluated through the soil quality index, SQI) increased by 15.30–43.42% under POS across both years, with maximal values observed at 50 M (2020) and 75 M (2021); similarly, the latex yield increased by 2.10–18.60%. SOC, NO₃⁻-N,C:P ratio, TN, and pH are the key factors that influence soil quality and latex yield. Structural equation modeling indicated that fertilization and soil factors collectively explained 82% of the variation in latex yield. These results demonstrated that POS effectively alleviated soil acidity, enhanced soil quality, and improved latex productivity, with 50% manure substitution treatment (50M) identified as the optimal short-term substitution strategy in rubber plantations. Full article

As a key tropical economic tree species, the girth of the rubber tree (Hevea brasiliensis) not only reflects its growth rate and timber yield but also determines tapping schedules and non-productive periods. This trait critically influences both the species’ economic value and latex production potential. Despite recent advances in genetic analyses of girth driven by genomic technologies, the number of identified key genes remains insufficient to support molecular breeding programs. This study focuses on 138 samples of rubber tree natural accessions, integrating phenotypic data analysis, population genetic structure analysis, and genome-wide association analysis (GWAS) to identify genetic loci and candidate genes associated with girth. Population stratification divides the tested accessions into four genetic groups: Groups Ⅰ and Ⅳ exhibit high genetic purity, while Groups Ⅱ and Ⅲ display hybrid characteristics. GWAS based on a mixed linear model detects 7 and 23 SNPs significantly associated with girth at p = 4.4 × 10⁻⁸ and p = 2.22 × 10⁻⁷, respectively. The most significant SNP is located at position 44994744 on chromosome CM021229.1. Under the highly significant association threshold, 27 candidate genes were identified, 4 of which are directly related to girth. Gene Ontology (GO) annotation of these 27 candidate genes reveals their primary involvement in metabolic regulation, signal transduction, and cell component construction. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis shows they are primarily enriched in the “aminoacyl-tRNA biosynthesis” and “glycolysis/gluconeogenesis” pathways. These findings provide significant theoretical support for genetic enhancement and mechanistic analysis of rubber tree growth traits. They reveal novel SNP markers and genes that complement existing genetic resources, refining breeding strategies for elite genotype selection and ultimately contributing to enhanced rubber production. Full article

The objective of this study was to investigate the influence of the lignocellulose filler originating in wood and non-wood raw materials, alone or together with collagen hydrolysate, on the properties and biodegradation ability of natural rubber latex. The different hydrophobicity of the polymer matrix and natural filler makes it difficult to obtain a homogenous structure of the composite. However, the easy biodegradation of the natural filler is a sufficient reason to seek a compromise between its useful properties and the environmental safety of the material. The composites were filled with lignocellulose filler: pine, spruce, and birch wood flour or willow, raspberry, and mallow non-wood flour. Collagen hydrolysate was used as a substitute for lignocellulosic filler, together or alone. The mechanical properties of the composites, their hardness, and equilibrium swelling were studied. In order to determine the morphology and interactions between filler and latex, scanning electron microscopy together with infrared spectroscopy were engaged. The results revealed that after the incorporation of 4 phr of the filler, the increase in mechanical strength was observed even despite the lack of compatibility between the filler and polymer matrix. The lignocellulose filler is a promising agent because its biodegradability contributes to the overall environmental safety of the polymer material. Full article

Occupational exposure to commercial formic and acetic acids through dermal contact and inhalation during rubber sheet processing poses significant health risks to workers. Additionally, the use of these acids contributes to environmental pollution by contaminating water sources and soil. This study investigates the potential of three types of wood vinegar—derived from para-rubber wood, bamboo, and eucalyptus—obtained through biomass pyrolysis under anaerobic conditions, as sustainable alternatives to formic and acetic acids in the production of ribbed smoked sheets (RSSs). The organic constituents of each wood vinegar were characterized using gas chromatography and subsequently mixed with fresh natural latex to produce coagulated rubber sheets. The physical and chemical properties, equilibrium moisture content, and drying kinetics of the resulting sheets were then evaluated. The results indicated that wood vinegar derived from para-rubber wood contained a higher concentration of acetic acid compared to that obtained from bamboo and eucalyptus. As a result, rubber sheets coagulated with para-rubber wood and bamboo vinegars exhibited moisture sorption isotherms comparable to those of sheets coagulated with acetic acid, best described by the modified Henderson model. In contrast, sheets coagulated with eucalyptus-derived vinegar and formic acid followed the Oswin model. In terms of physical and chemical properties, extended drying times led to improved tensile strength in all samples. No statistically significant differences in tensile strength were observed between the experimental and reference samples. The concentration of acid was found to influence Mooney viscosity, the plasticity retention index (PRI), the thermogravimetric curve, and the overall coagulation process more significantly than the acid type. The drying kinetics of all five rubber sheet samples displayed similar trends, with the drying time decreasing in response to increases in drying temperature and airflow velocity. Full article

This study aims to investigate the application of nuclear magnetic resonance (NMR) to characterize mortars containing recycled rubber waste as an eco-innovative material for sustainable construction. The primary objective was to analyze the way rubber granules influence hydration kinetics, microstructural development and pore structure. The innovative mortar formulations incorporated rubber granules, casein, natural hydraulic lime (NHL), and latex. NMR analysis revealed distinct T₂ relaxation time distributions correlated with different pore sizes and water states: shorter T₂ values demonstrate strongly bound water in small pores, while longer T₂ values are associated with loosely bound or free water in larger pores. The formulation with 3.5% NHL and 5% rubber granules exhibited optimal microstructural characteristics. These results reveal that NMR is a valuable, non-destructive tool for monitoring cementitious material evolution and supporting the use of tire-derived waste in eco-innovative mortar designs. Full article

Natural rubber skim latex is commonly discarded as waste or turned into skim natural rubber products such as skim crepe and skim blocks. It is challenging to retrieve all residual rubbers in skim latex since it has a very low rubber content and many non-rubber components like protein. Manufacturers conventionally utilize concentrated sulfuric acid as a coagulant. This method generates many effluents and hazardous pollutants that negatively impact the environment. This work presents an innovative method for enhancing the skim latex’s value by employing an ultrafiltration membrane. This study aims to establish a hydrophilic PVDF-TiO₂ mixed-matrix membrane. The skim latex was processed through a membrane-based ultrafiltration process, which yielded two products: skim latex concentrate and skim serum. Skim latex deposits that cause fouling on the membrane surface can be identified by SEM-EDX and FTIR analysis. The PVDF–PVP-TiO₂ mixed-matrix membrane generated the maximum skim serum flux of 12.72 L/m²h in contrast to the PVDF pure membranes, which showed a lower flux of 8.14 L/m²h. CHNS analysis shows that a greater amount of nitrogen, which is indicative of the protein composition, was successfully extracted by the membrane separation process. These particles may adhere to the membrane surface during filtration, obstructing or decreasing the number of fluid flow channels. The deposition reduces the effective size of membrane pores, leading to a decline in flux rate. The hydrophilic PVDF-TiO₂ mixed-matrix membrane developed in this study shows strong potential for application in the latex industry, specifically for treating natural rubber skim latex, a challenging by-product known for its high fouling potential. This innovative ultrafiltration approach offers a promising method to enhance the value of skim latex by enabling more efficient separation and recovery. Full article

Natural rubber is a widely used biological polymer material because of its excellent comprehensive performance. Nevertheless, the performance of domestic natural rubber cannot meet the requirements for high-end products such as aviation tires, which has become a constraint on the innovation and upgrading of high-end manufacturing enterprises and the enhancement of global competitiveness in China. To solve the bottleneck problem of natural rubber processing technology, this study systematically analyzed the effects of different varieties of fresh latex ratios on the processing and dynamic properties of bio-coagulated natural rubber. By mixing PR107 and Reyan72059 fresh latex with Reyan73397 fresh latex according to proportion, the fresh latex was coagulated by enzyme-assisted microbials, and the effects of the fresh latex ratio on physical and chemical indexes, molecular weight distribution, vulcanization characteristics, processing properties, cross-link density and physical and mechanical properties of the natural rubber were analyzed. The results showed that the aging resistance of natural rubber coagulated with enzyme-assisted microbial decreased, and the aging resistance of natural rubber increased with the increase in the mixing ratio of PR107 and Reyan72059 fresh latex. The proportion of high molecular weight of the natural rubber coagulated with the enzyme-assisted microbial increased, and the fresh latex mixing had little effect on the molecular weight distribution curve. Under the carbon black formulation, the CRI of the enzyme-assisted microbial coagulated natural rubber compound was relatively larger. Under the same strain conditions, the H-3 compound (PR107:Reyan72059:Reyan73397 = 1:1:3) had the best viscoelasticity and the least internal resistance of rubber molecules. In addition, the cross-link density, tensile strength, elongation at break, and tear strength of H-3 vulcanized rubber were the largest, improved by 23.08%, 5.32%, 12.45% and 3.70% compared with the same H-2 vulcanized rubber. In addition, the heat generation performance was reduced by 11.86%, and the wear resistance improved. Full article

It is challenging for mortar to simultaneously enhance the transmission property of water vapor while maintaining excellent waterproofness and impermeability. However, in some applications, both are necessary. Therefore, three different kinds of modifiers, i.e., cementitious capillary crystalline waterproof materials (XYPEX), γ-methacryloxy-propyl-trimethoxy-silane (KH570), and styrene-butadiene rubber latex (SB), are employed to explore how modified mortar can possess excellent waterproofness, impermeability, and the water vapor transmission property simultaneously. Combining characterization techniques, the influencing factors of these three properties are studied. The results indicate that XYPEX promotes the formation of hydration products within pores, improves waterproofness and impermeability, but decreases the water vapor transmission property. KH570 introduces numerous pores ranging from 0.1 to 5 micrometers and enhances the hydrophobicity of mortar; at 1.25% and 2.5% contents, the modified mortar exhibits excellent waterproofness and water vapor transmission property but poor impermeability. SB introduces numerous air pores and forms polymer films; at 20% content, the modified mortar exhibits excellent waterproofness and water vapor transmission property, with impermeability remaining unchanged, making SB a favorable modifier that combines these three properties. Finally, the mechanisms of these three properties are discussed, which provides a theoretical reference for the control of mortar’s waterproofing, impermeability, and water vapor transmission. The selection of modifiers is based on the actual performance requirements. Full article