Equivalent Weight Research Articles

Optimization of microwave-assisted pectin extraction from walnut shells and evaluation of its physicochemical and biological attributes

Walnuts, known for their high nutritional value, generate significant waste in the form of husks and shells, the disposal of which contributes to environmental pollution. The utilization of this walnut waste for the production of beneficial compounds remains underexplored. In the current study, extraction time, temperature, microwave power, and solid-to-solvent ratio were optimized using response surface methodology. This technique significantly reduced the extraction time, yielding pectin at 34.13 ± 3.83 % under optimal conditions: temperature (74 °C), microwave power (400 W), irradiation time (16 min), and solid-solvent ratio (1:25). XRD characterization revealed the crystalline nature of the extracted pectin, while FTIR confirmed the presence of major functional groups. The extracted pectin exhibited an equivalent weight of 576.99 ± 7.63 g/mol with a degree of esterification of 59.88 ± 0.28 %, making it suitable for food, pharmaceutical, and cosmetic applications. Further, the extracted pectin demonstrated significant antioxidant activity with IC50 values of 5.08 ± 0.08 mg/ml for DPPH and 2.87 ± 0.023 mg/ml for ABTS assays. It also showed antibacterial activity against both gram-positive Staphylococcus aureus MTCC 96 and gram-negative Pseudomonas aeruginosa MTCC 424, with zones of inhibition measuring 25.33 ± 0.58 mm and 28.33 ± 0.58 mm, respectively. SEM analysis revealed changes in cell morphology of S. aureus and P. aeruginosa when treated with the extracted pectin. These findings suggest that microwave-assisted extraction offers a rapid, eco-friendly, and cost-effective method for pectin extraction from walnut shells, promoting sustainable utilization of this waste resource and providing a potential pectin source with enhanced biological activity.

PECTIN EXTRACTION AND CHARACTERIZATION FROM LOCAL WHITE PUMPKIN (LAGENARIA SICERARIA)

Pectin, a naturally occurring heteropolysaccharide, has in recent years grown increasingly in importance. In this present study, white pumpkin or bottle gourd was chosen as a representative of the Cucurbitaceae family to extract powder pectin. At initial and final times, treatment (T1) and treatment (T2), the amount of pectin in calcium pectate in fresh pumpkin ranges from 3.7% to 5.8%. Standardized water bath heating was used to extract pectin from white pumpkins by boiling the fruit at atmospheric pressure for five minutes at 95 oC. Distilled water was also tested for pectin isolation from white pumpkins as an extraction solvent. The weight increased by 844.98% at T1 and decreased to 675.67% at T6, following which was precipitation with 95% ethanol yielding maximum on the above during the extraction of pectin by water bath at varied period durations. Finally, the degree of esterification was the rate 68.76% at T1 to 59.87% at T6, with the methoxyl content having a value 9.45% at T1 to 6.82% at T6 and the anhydrouronic acid content (AUA%) being 76.66% at T1 to 64.77% at T6. Moisture, equivalent weight, degree of esterification, and methoxyl concentration all reduced as extraction time increased. However, many indicators, like ash content, acetyl value, and jelly grade, exhibited an early rise in value that later declined as extraction time increased. Thus, the optimal method for pectin isolation involves boiling the pumpkin in water at atmospheric pressure for 5 to 30 minutes. In addition, among different times of extraction pectin that was obtained from 30 minutes had the highest lightness 82.07 while the lowest redness 2.03 and yellowness 5.14 of pectin was recorded at this time. This pectin met the criteria for food additive use, indicating its potential as a commercially viable alternative source.

Impact of Zinc oxide nanoparticles on biosynthesis of Thymoquinone in cell cultures of Nigella sativa

The rising market interest for Nigella sativa (Black seeds) necessitates the development of cultivation strategies to enhance metabolites production. Zinc oxide nanoparticles (ZnO-NPs) have drawn global attention as efficient and bio safe elicitors for in vitro cultures, to enhance secondary metabolites production in medicinal plants. In this study, ZnO-NPs were utilized for establishment of callus and cell cultures in black seeds for the first time. Hypocotyl explants were cultured on Murashige and Skoog (MS) media with varying levels of ZnO-NPs, resulted in callus induction and biomass formation. Optimal response in callus growth parameters were observed when explants were grown on MS media supplemented with 60mg/L ZnO-NPs, resulting in 71.2% callus induction frequency, 28.2g/L fresh biomass, 9.7g/L dry biomass, and 63% water content. A substantial increase in callus growth was observed when ZnO-NPs were combined with 6-Benzylaminopurine (BA) at ratio of 45:1.5mg/L, resulting in 91.2% callus induction frequency and 42.2g/L fresh biomass. In cell suspension cultures, ZnO-NPs alone at 45mg/L produced optimum callus biomass (60.9g/L). However, in combination with BA, callus biomass did not increase significantly in cell cultures. Maximum accumulation of total phenolic content (TPC: 26.8mg GAE/g DW; Gallic acid equivalent dry weight) and total flavonoid content (TFC: 19.5mg QE/g DW; Quercetin equivalent dry weight) was observed in cell cultures treated with higher concentration (70mg/L) of ZnO-NPs in the 5th week of the growth curve. Moreover, ZnO-NPs incremented substantially the Phenylalanine lyase (PAL), Superoxide dismutase (SOD) and Peroxidase (POD) enzyme activities in cell cultures. Nonetheless, Reverse Phase High Performance Liquid Chromatography (RP-HPLC) analysis indicated peak production of tymoquinone (168.5mg/g FW) in cell cultures treated with 45mg/L ZnO-NPs alone. This study offers a promising approach for commercial production of Nigella sativa biomass and bioactive metabolites.

Metabolomic Fingerprints of Medical Therapy Versus Bariatric Surgery in Patients With Obesity and Type 2 Diabetes: The STAMPEDE Trial.

Roux-en-Y gastric bypass (RYGB) and sleeve gastrectomy (SG) are effective procedures to treat and manage type 2 diabetes (T2D). However, the underlying metabolic adaptations that mediate improvements in glucose homeostasis remain largely elusive. The purpose of this study was to identify metabolic signatures associated with biochemical resolution of T2D after medical therapy (MT) or bariatric surgery. Plasma samples from 90 patients (age 49.9 ± 7.6 years; 57.7% female) randomly assigned to MT (n = 30), RYGB (n = 30), or SG (n = 30) were retrospectively subjected to untargeted metabolomic analysis using ultra performance liquid chromatography with tandem mass spectrometry at baseline and 24 months of treatment. Phenotypic importance was determined by supervised machine learning. Associations between change in glucose homeostasis and circulating metabolites were assessed using a linear mixed effects model. The circulating metabolome was dramatically remodeled after SG and RYGB, with largely overlapping signatures after MT. Compared with MT, SG and RYGB profoundly enhanced the concentration of metabolites associated with lipid and amino acid signaling, while limiting xenobiotic metabolites, a function of decreased medication use. Random forest analysis revealed 2-hydroxydecanoate as having selective importance to RYGB and as the most distinguishing feature between MT, SG, and RYGB. To this end, change in 2-hydroxydecanoate correlated with reductions in fasting glucose after RYGB but not SG or MT. We identified a novel metabolomic fingerprint characterizing the longer-term adaptations to MT, RYGB, and SG. Notably, the metabolomic profiles of RYGB and SG procedures were distinct, indicating equivalent weight loss may be achieved by divergent effects on metabolism.

PENGARUH KONSENTRASI ASAM KLORIDA (HCl) DAN WAKTU EKSTRAKSI PADA KARAKTERISASI PEKTIN KULIT JERUK BALI (Citrus maxima)

Pectin or pectate compounds are complex polysaccharides with large molecular weights found in the middle lamella or intercellular spaces in higher plant tissues. The main function of pectin is as a thickener and gelling agent. So far, pectin production in Indonesia has not been widely known and developed. Pectin can be obtained from fruit peels, one of which is grapefruit peel. Grapefruit has a fairly high pectin content, around 30%. The purpose of this study was to find out how much pectin content is in grapefruit peels by determining the concentration of hydrochloric acid and the right extraction time to get the best yield and quality of pectin. This study used a randomized block design (RBD) method with two factors, namely the concentration of hydrochloric acid 0.2 N; 0.25 N and 0.3 N and extraction times of 60, 90 and 120 minutes with three repetitions. The observations made were yield pectin, water content, ash content, equivalent weight, methoxyl content, galacturonic acid and degree of esterification. The data obtained based on the research results were analyzed statistically with variance (α = 0.05) and continued with the Duncan Multiple Range Test (DMRT). The results showed that the concentration of hydrochloric acid 0.3 N and extraction time of 120 minutes produced the best pectin with yield 13.57%, moisture content 8.27%, ash content 7.53%, methoxyl content 6.79%, galacturonic content 261 .65%, the degree of esterification is 14.82% and it can be concluded that the test results for the characteristics of the pectin produced meet the established standards of the International Pectin Producers Association (IPPA).

Controllable Synthesis of Chain Center Dye-Labeled Star Polymers for Quantitative Examination of Interchain Conformation by Time-Resolved Fluorescence Resonance Energy Transfer.

Using a "core-first" approach with atom transfer radical polymerization, fluorescent center-functional star polymers of equivalent molecular weight but with varying numbers of arms (di-, tri-, and tetra-arm) were prepared. The sensitivity of fluorescence, combined with a dye-labeling technique introducing a fluorescent donor (carbazole) and an acceptor (anthracene) at the center of poly(methyl methacrylate) (PMMA) chains, enabled the application of time-resolved fluorescence resonance energy transfer to obtain quantitative insights into the conformation of the star polymer chains in the film state. When the results of star-branched polymers were compared with those of linear polymers of identical type and molecular weight, the impact of branching on polymer behavior was isolated for examination. Although the star topology does not alter the average intercoil distance, it affects the distance dispersity. Star polymers with higher arm numbers display decreased dispersity from distance due to reduced intermolecular aggregation at their geometric centers. This study presents the first spectroscopic evidence regarding the distribution of geometric centers in star polymers, offering a physical understanding of chain interpenetration and entanglement within star polymers.

Unripe bael pulp pectin extraction and characterization using the microwave assisted method.

In this study, pectin was extracted from unripe bael using a microwave-assisted extraction technique. Optimization was done based on independent and dependent parameters. Pectin yield was the dependent variable in the study, whereas the independent factors were microwave power, time, and solid solvent ratio. Pectin extraction was carried out using different combinations of microwave power (180, 360, 540 watts), time (1, 2, 3 minutes), and the ratio of solid-solvent (1:20, 1:30, 1:40 g/mL). Using Box-Behnken response surface methodology, 17 experimental runs were performed. A microwave power of 360 watts, a time of 3 minutes, and a solid solvent ratio of 1:20 g/mL were the ideal parameters that achieved the maximum pectin yield of 19.8%. The yield of pectin was analyzed using multiple regression statistical analysis. Qualitative and quantitative analysis of pectin yield was studied, which revealed an equivalent weight of 263.15, a methoxyl content of 9.92 percent, anhydrouronic acid content of 123.2%, and a degree of esterification of 45.71%.

Unraveling the nanostructures and self-assembly behavior of perfluorosulfonic acid in water/ethanol solvent: Effect of EW and side-chain chemistry

The perfluorosulfonic acid (PFSA) ionomers are key materials for proton exchange membranes (PEMs) and catalyst layers (CLs). Their morphology is profoundly influenced by the chain assembly behavior of PFSA in dispersions. Hence, we combine the characterization techniques of dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and cryo-transmission electron microscopy (Cryo-TEM) to study the nanostructures of PFSA dispersions, and provide a structure model for diverse PFSA ionomers in water/ethanol solvent. It is seen that PFSA ionomers self-assembly into a rod-like particle in dilute dispersion. As the concentration increases, the primary rod aggregates gradually assemble into a swollen- or Gaussian-network structure. Beyond this feature, we see that different PFSA ionomers show different nanostructures in dispersion. For the long-side-chain (LSC) PFSA ionomers, the 800-LSC PFSA tends to form monodisperse rod-like aggregates that is in a highly ordered arrangement with a rod diameter of 3.16 nm and a length of 28.72 nm. As the equivalent weight (EW) increases to 960, the poor solubility of the main chains in water/ethanol solvents leads to the “end-to-end” assemblies of the primary rod particles and dendritic secondary aggregates. The short-side-chain (SSC) PFSA ionomer that shares the same backbone with 960-LSC PFSA exhibit remarkable mono-dispersity and ordered arrangement of rod-like aggregates in water/ethanol solvents due to the strong electrostatic repulsion.

Effect of wing height layout on the aerodynamic performance ofhigh-speed train

PurposeThis paper aims to investigate the effect of different wing height layouts on the aerodynamic performance and flow structure of high-speed train, in a train-wing coupling method with multiple tandem wings installed on the train roof.Design/methodology/approachThe improved delayed detached eddy simulation method based on shear stress transport k-ω turbulence model has been used to conduct computational fluid dynamics simulation on the train with three different wing height layouts, at a Reynolds number of 2.8 × 106. The accuracy of the numerical method has been validated by wind tunnel experiments.FindingsThe wing height layout has a significant effect on the lift, while its influence on the drag is weak. There are three distinctive vortex structures in the flow field: wingtip vortex, train body vortex and pillar vortex, which are influenced by the variation in wing height layout. The incremental wing layout reduces the mixing and merging between vortexes in the flow field, weakening the vorticity and turbulence intensity. This enhances the pressure difference between the upper and lower surfaces of both the train and wings, thereby increasing the overall lift. Simultaneously, it reduces the slipstream velocity at platform and trackside heights.Originality/valueThis paper contributes to understanding the aerodynamic characteristics and flow structure of a high-speed train coupled with wings. It provides a reference for the design aiming to achieve equivalent weight reduction through aerodynamic lift synergy in trains.

Genomic Selection of Large Yellow Croaker (Larimichthys crocea) with a High Plant Protein Diet Enhances the Growth Performance of Offspring.

Fishmeal is over-represented in the diets of large yellow croaker (Larimichthys crocea), and this farming mode, which relies heavily on fishmeal, is highly susceptible to the price of fishmeal and is unsustainable. Therefore, more and more studies on the large yellow croaker tend to replace fishmeal with land-based animal or plant proteins, but few studies have considered it from the genomic selection. In this study, we evaluated the survival rate (SR), final body weight (FBW), body weight gain (BWG), weight gain rate (WGR), and specific growth rate (SGR) of the large yellow croaker GS7 strain, which was obtained through genomic selection for tolerance to plant proteins and analyzed the differences in plant protein utilization between the GS7 strain and unselected commercial large yellow croaker (control group). The results of separate feeding for 60days showed that although there was no significant difference in SR between the control and GS7 strains (P > 0.05), the BWG, WGR, and SGR of the control were significantly lower (P < 0.05) than those of the GS7 group. Results of mixed feeding after PIT marking showed that compared to the control fish, the GS7 strain had significantly higher BWG, WGR, and SGR (P < 0.0001). To make the experimental results more precise, we compared fishes with equivalent initial body weight (IBW) in the GS7 strain and the control group. The final fish body weight (FBW) of Ctrl-2 (IBW 300-399g) and Ctrl-4 (IBW 500-599g) was significantly lower than those of the corresponding GS7-2 and GS7-4 (P < 0.05), while the FBW of Ctrl-1 (IBW 200-299g) and Ctrl-3 (IBW 400-499g) was much significantly lower than the corresponding GS7-1 and GS7-3 (P < 0.01). The BWG, WGR, and SGR of Ctrl-1 and Ctrl-4 were more significantly lower than those of the corresponding GS7-1 and GS7-4 (P < 0.01), while the BWG, WGR, and SGR of Ctrl-2 and Ctrl-3 were more significantly different from the corresponding GS7-2 and GS7-3 (P < 0.0001). Our results seem to point toward the same conclusion that the GS7 strain is better adapted to high plant protein diets than the unselected commercial large yellow croaker. These results will provide a reference for the low-fishmeal culture industry of large yellow croakers and the selection and breeding of strains tolerant to a high percentage of plant proteins in other marine fishes.

In-Situ Characterization of Cathode Catalyst Degradation in PEM Fuel Cells

The composition and morphology of the cathode catalyst layer (CCL) have a significant impact on the performance and stability of polymer electrolyte membrane fuel cells (PEMFC). Understanding the primary degradation mechanism of the CCL and its influencing factors is crucial for optimizing PEMFC performance and durability. Within this work, we present comprehensive in-situ characterization data focused on cathode catalyst degradation. The dataset consists of 36 unique durability tests with over 4000 testing hours, including variations in the cathode ionomer to carbon ratio, platinum on carbon ratio, ionomer equivalent weight, and carbon support type. The applied accelerated stress tests were conducted with different upper potential limits and relative humidities. Characterization techniques including IV-curves, limiting current measurements, electrochemical impedance spectroscopy, and cyclic voltammetry were employed to analyse changes in performance, charge and mass transfer, and electrochemically active surface area of the catalyst. The aim of the dataset is to improve the understanding of catalyst degradation by allowing comparisons across material variations and provide practical information for other researchers in the field.

Potentials of Mahachanok mango peel pectin in modulating glycaemic index in simulated in vitro carbohydrate digestion of meat product

Pectin derived from mango peel biomass offers a noteworthy alternative to starch in food products, potentially assisting in controlling hyperglycaemia by impacting starch digestion. Consequently, this study evaluates the potential of Mahachanok mango peel (MHMP) pectin in glycaemic index (GI) reduction of meat products using simulated in vitro carbohydrate digestion. The physicochemical characteristics of MHMP pectin (MHMPP) were assessed using both FTIR and titration techniques, with microarray polymer profiling employed to analyse the glycan profile. In vitro simulations of carbohydrate digestion were carried out to assess its efficacy. Additionally, meatballs fortified with MHMPP were formulated, and the glycaemic index of the resultant products was ascertained. Microarray polymer profiling revealed distinct glycans in different fractions, including galactose, xyloglucan, and glycoprotein. Microwave extraction of pectin yielded 19.04 % MHMPP content with specific characteristics: L* (58.04), a* (12.80), b* (23.50), 6.81 % moisture content, and 78.63 % solubility. The degree of esterification at 55.73 %, an equivalent weight of 789.26 mg/moL, and a methoxyl content of 8.39 %, evidently identified MHMPP as high-methoxyl pectin. In a simulated system of MHMPP, content correlates with reduced digestion, supported by lowered values across the hydrolysis index (HI), rapidly available glucose (RAG), slowly available glucose (SAG), and expected glycaemic index (eGI). Higher MHMPP levels consistently exhibit a decreased impact on these digestive factors. In a simulated meat product system, increased MHMPP content corresponded to slower digestion rates, indicating its potential to retard digestion, as supported by HI, RAG, SAG, and eGI. The supplementation of 25 % pectin to meatballs is the most successful treatment, as it results in eGI, RAG, and SAG values of 8.71 (mg/gsample), 6.65 (mg/gsample), and 1.85 (mg/gsample), respectively. This study highlights the advantage of MHMP-derived dietary fibre in product development from industrial byproducts, aligning with sustainable development goals by reducing reliance on non-renewable materials.

Microwave-assisted acid extraction of high-methoxyl kinnow (Citrus reticulata) peels pectin: Process, techno-functionality, characterization and life cycle assessment

The present study assessed the efficacy of kinnow peel pectin-acetic acid extraction using microwave heating at 110 °C, pH 2.2 for 10 min with a 1:2 ratio supernatant to ethanol for higher yield. The kinnow peel was freeze dried and grinded to fine powder for pectin extraction. The microwave extracted (ME) kinnow pectin showed 833 mg equivalent weight, 7.44 % methoxyl content, 66.67 % degree of esterification, 63.15 % galacturonic acid content and evinced higher purity than commercial citrus pectin. ME kinnow pectin exhibited shear thinning behaviour while higher apparent viscosity (Pa. s) at 20 % concentration. The ME kinnow pectin showed characteristic functional groups and a less crystalline structure as deduced from FT-IR, SEM and XRD respectively, and a higher thermal decomposition analysed from TGA. Further, life cycle assessment (LCA) predicted that the ethanol and acetic acid were major contributors toward climate change in this study. ME kinnow pectin has the potential to be used as a commercial pectin in various food applications.

Optimization of subcritical water extraction for pectin extraction from cocoa pod husks using the response surface methodology

This study optimized subcritical water extraction (SWE) conditions to maximize pectin yield from cocoa pod husk (CPH) and compared the characteristics of CPH pectin extracted through SWE with those of CPH pectin obtained through conventional extraction (CE) with citric acid. The Box–Behnken experimental design was employed to optimize SWE and examine the influence of process parameters, including temperature (100 °C–120 °C), extraction time (10–30 min), and solid:liquid ratio (SLR) (1:30–2:30 g/mL), on pectin yield. The maximum pectin yield of 6.58% was obtained under the optimal extraction conditions of 120 °C for 10 min with 1:15 g/mL SLR and closely corresponded with the predicted value of 7.29%. Compared with CE, SWE generated a higher yield and resulted in a higher degree of esterification, methoxyl content, and anhydrouronic acid value but a lower equivalent weight. The extracted pectin was pure, had low-methoxyl content, and similar melting and degradation temperatures.

Effects of Defatting Pretreatment on Polysaccharide Extraction from Rambutan Seeds Using Subcritical Water: Optimization Using the Desirability Approach.

Rambutan seeds are by-products generated from fruit-processing factories; the leftover seeds are buried in landfills, generating methane emissions. This work aimed to extract polysaccharides (POLS) from rambutan seeds by using subcritical water extraction (SWE). The effects of defatting pretreatment and operating parameters in SWE were investigated using a Box-Behnken design. The results show that defatting pretreatment significantly enriched the POLS yield, while it had no significant effect on the total sugar content. Using the desirability approach, the suitable feedstock for SWE was defatted rambutan seeds. The maximum desirability of 0.86 was found at a temperature range of 145-150 °C, an extraction time of 15 min, and a liquid-solid ratio of 10:1. The POLS yield and total sugar content were in the range of 52.33-55.63 g/100 g feedstock and 83.37-87.45 g/100 g POLS, respectively. The extracted POLS had an equivalent molecular weight of 413.70 kDa that could be used as an extender in plant-based products. In conclusion, the defatting pretreatment of rambutan seeds not only improved the POLS yield obtained via SWE but also generated additional lipids that could be utilized as an unconventional source of specialty fat.

Extraction and characterization of pectin from coffee (Coffea arabica L.) pulp obtained from four different coffee producing regions

The pectin was extracted using H2SO4, HNO3, and HCl from the pulp of four coffee varieties (Harar, Sidama, Jimma, and Guji) collected from different regions of Ethiopia. The effect of extraction temperature, time, solid-to-liquid ratio, types of acid and coffee varieties on the physiochemical properties and yield of pectin were studied. A maximum pectin yield, which was 12.7 %, was obtained from Harar coffee pulp treated with H2SO4. The equivalent weight of the extracted pectin varied from 1111 to 1667 g/mol. The methoxyl contents of the extracted pectin ranged from 4.23 to 7.13 %. The degrees of esterification and anhydrouronic acid of the pectin ranged from 53 to 68.5 % and 35.5 to 68.8 %, respectively. The results show the yield and physiochemical properties of the coffee pulp pectin depend on extraction parameters, acid types, and coffee varieties. Moreover, the pectin extracted from coffee pulp showed strong gelling properties.

Chronic treatment with glucagon-like peptide-1 and glucagon receptor co-agonist causes weight loss-independent improvements in hepatic steatosis in mice with diet-induced obesity

ObjectivesCo-agonists at the glucagon-like peptide-1 and glucagon receptors (GLP1R/GCGR) show promise as treatments for metabolic dysfunction-associated steatotic liver disease (MASLD). Although most co-agonists to date have been heavily GLP1R-biased, glucagon directly acts on the liver to reduce fat content. The aims of this study were to investigate a GCGR-biased co-agonist as treatment for hepatic steatosis in mice. MethodsMice with diet-induced obesity (DIO) were treated with Dicretin, a GLP1/GCGR co-agonist with high potency at the GCGR, Semaglutide (GLP1R monoagonist) or food restriction over 24 days, such that their weight loss was matched. Hepatic steatosis, glucose tolerance, hepatic transcriptomics, metabolomics and lipidomics at the end of the study were compared with Vehicle-treated mice. ResultsDicretin lead to superior reduction of hepatic lipid content when compared to Semaglutide or equivalent weight loss by calorie restriction. Markers of glucose tolerance and insulin resistance improved in all treatment groups. Hepatic transcriptomic and metabolomic profiling demonstrated many changes that were unique to Dicretin-treated mice. These include some known targets of glucagon signaling and others with as yet unclear physiological significance. ConclusionsOur study supports the development of GCGR-biased GLP1/GCGR co-agonists for treatment of MASLD and related conditions.

Maximum buckling load design and post-buckling compressive failure of curved grid sub-stiffened composite panels

The structural efficiency of composite stiffened panels can be substantially improved by utilizing curved stiffening components due to their exceptional mechanical performance and design flexibility. This paper aims to explore the impressive potential offered by the curved stiffening concept in the design of T-shaped stiffened composite panels featuring curved sub-stiffening components. An optimization design framework is proposed to optimize the laminates sequence of skin, ply orientation angles and distribution of the curved sub-stiffeners as well as the curvature of the sub-stiffeners of the proposed curved grid sub-stiffened composite panels to yield higher buckling performance without additional weight. Results demonstrate that introducing composite curved grid sub-stiffeners to the T-shaped stiffened composite panel leads to substantial improvements (+254.42%) in buckling performance, while maintaining equivalent weight designs. Furthermore, the introduction of composite curved grid sub-stiffeners reveals alterations to the post-buckling deformation paths of grid sub-stiffened composite panels, leading to varied collapse loads and degrees of deformation in the composite panels. This highlights the importance of utilizing the composite curved grid sub-stiffeners to improve stability and reduce the risk of failure in thin-walled structures, all while meeting lightweight design criteria.

Effects of rapid or slow body weight reduction on glucose tolerance during equivalent weight loss in rats fed high-fat diet

Effects of rapid or slow body weight reduction on glucose tolerance during equivalent weight loss in rats fed high-fat diet

Estimation on the hourly near-surface temperature lapse rate and its time-varying characteristics

Since much of the current researches have focused on daily, monthly or annual near-surface (2 m) temperature lapse rate (NSTLR), there is little guidance on best estimation practices and analyses of time-varying characteristics for the hourly NSTLR. To estimate hourly NSTLR and identify its time-varying characteristics accurately and objectively, this study proposed a robust estimation strategy based on IGGIII equivalent weight using multiple linear regression models. The accuracy and reliability of the proposed method was verified. The results show that the robust estimation strategy can further improve the hourly NSTLR solution accuracy relative to the least square (LSQ) method, especially in the time period of relatively high temperature. The hourly NSTLR was positively correlated with temperature, with a 24-h average maximum of 0.604 °C/100 m at universal time coordinated (UTC) 7.2 h and minimum of 0.284 °C/100 m at UTC 20.5 h, respectively. Throughout the year, the NSTLR was the largest from June to August, with an average median of around 0.492 °C/100 m. However, from November to the following January, the NSTLR value was the smallest, with a mean median of about 0.323 °C/100 m. In addition, the hourly NSTLR values were essentially less than the constant value of 0.65 °C/100 m. When the hourly NSTLR estimated based on the proposed method was applied to the temperature interpolation, the interpolation accuracies at the highest altitude (1545 m) and other meteorological stations (below 310 m) can increase by 22.4 % and 8.1 %, respectively, relative to the hourly NSTLR calculated by the LSQ method, and increased by 55.6 % and 13.0 %, respectively, relative to the no-NSTLR correction. The results are important for the fine establishment of high spatiotemporal resolution temperature fields and for the study of climatic phenomena characterized with rapid spatiotemporal variation.