Simple Assembly Research Articles

Modular Assembly of Photoactive Lipid Nanoparticles on Red Blood Cells toward Enhanced Phototherapy Efficacy.

Photodynamic therapy has been developed as a promising treatment for malignant tumors, which inspires research into photosensitizers. However, the therapeutic efficacy of individual photosensitizers is often hampered by the physiological environment. The assembly of biological materials with synthetic molecules offers a strategy to enhance functionality while improving tolerance to varying physiological conditions. Herein, we present a biohybrid system for enhanced phototherapy efficacy through a simple two-step assembly process. Photoactive lipid nanoparticles were assembled based on synthesized conjugated molecules and lipophilic prodrugs, which were then modularly assembled with red blood cells (RBCs). Driven by hydrophobic and electrostatic interactions, hydrophobic conjugated molecules were efficiently incorporated into the RBCs, while lipophilic prodrugs were simultaneously inserted into the cell membranes. The engineered RBCs harnessed the natural oxygen transport capability, enabling the internal conjugated molecules to effectively produce reactive oxygen species (ROSs) even under oxygen-poor conditions. Meanwhile, the use of ROS-cleavable linkers in prodrugs enhanced drug release for chemotherapy, which is a perfect complement to photodynamic therapy. In vitro and in vivo experiments proved the improved phototherapy efficacy of the biohybrid system. Furthermore, the changes in aggregation directed Förster resonance energy transfer between conjugated molecules and fluorescent drugs provided a mechanism to track drug release from engineered RBCs. Therefore, the modular assembly of biohybrid systems can offer multiple functionalities required for phototherapy, on-demand drug release, and imaging.

Chemical reactions regulated by phase-separated condensates

Phase-separated liquid condensates can spatially organize and thereby regulate chemical processes. However, the physicochemical mechanisms underlying such regulation remain elusive as the intramolecular interactions responsible for phase separation give rise to a coupling between diffusion and chemical reactions at nondilute conditions. Here, we derive a theoretical framework that decouples the phase separation of scaffold molecules from the reaction kinetics of diluted clients. As a result, phase volume and client partitioning coefficients become control parameters, which enables us to dissect the impact of phase-separated condensates on chemical reactions. We apply this framework to two chemical processes and show how condensates affect the yield of reversible chemical reactions and the initial rate of a simple assembly process. In both cases, we find an optimal condensate volume at which the respective chemical reaction property is maximal. Our work can be applied to experimentally quantify how condensed phases alter chemical processes in systems biology and unravel the mechanisms of how biomolecular condensates regulate biochemistry in living cells. Published by the American Physical Society 2024

Substantiation of rational design parameters of a crusher with two movable jaws

Purpose. Design engineering of the mechanism of a two-jaw crusher with a compound motion of the jaws, which ensures a change in the angle of gripping of pieces of material within a very small range. Methodology. In the work, a theoretical study on the fourth-class lever mechanism, as the basis of a two-jaw crusher, was performed using the Mathcad 15 software. The study was performed on a vector representation of the links of the hinged mechanism. The development and analysis of constructive solutions were performed using the Autocad software product, which reduces the risk of errors and increases the quality of the design process. Findings. The paper theoretically determines the rational geometric parameters of the two-jaw crusher with the optimal value of the nip angle, whose crushing chamber is formed by the closed loop circuit of the flat fourth-class lever mechanism and proposes a new constructive solution of the mechanism for adjusting the crusher opening with two movable jaws and the bottom mounting of eccentric nodes. The developed device in the form of separate blocks is made with the possibility of their simple assembly and disassembly, which ensures the rate and quality of replacing lining plates or surfacing restoration of the worn working surface of the jaws. The relative movement of the jaws ensures the crushing of pieces of material with the required crushing coefficient. The geometric parameters were obtained by the method of kinematic synthesis. The geometric parameters of the crushing chamber of the two-jaw crusher were determined theoretically; the dependence was obtained of the change in the nip angle on the height of the movable jaw over a period of movement and the change in the compression stroke, which ensures the force interaction of the working surface of the jaws with the material. Originality. It is proved that the quadrilateral closed circuit of the fourth-class lever mechanism can be used as a crushing chamber of a two-jaw crusher. Two links of a closed circuit operate as jaws which break pieces of material. At the same time, the nip angle can vary within fairly narrow limits, ensuring the optimality of the crushing process. It was established that the considered option of the fourth-class six-link mechanism geometry has only two folds. An algorithm is presented for searching for assemblies with the purpose of identifying those that are closely adjacent. Practical value. The results of the conducted research provide the theoretical background and the algorithm for determining the optimal parameters of a two-jaw crusher which can be used at the stage of designing similar crushers. The developed design solution for adjusting the crusher opening expands the scope of application of double-jaw crushers. The obtained dependences of the change in the angle of inclination and the working surface of the jaw over a period make it possible to develop a rational mode of crushing the material

Cu2+-mediated telomeric dimeric G-quadruplex DNAzyme for highly sensitive colorimetric detection of deferasirox

Deferasirox (DEF) is an important iron chelator for treatment of iron overload–related diseases. Monitoring DEF concentration in human serum will provide some valuable information for clinical diagnosis and therapy of such diseases. In this study, we developed a peroxidase-mimicking colorimetric sensor for the detection of DEF by simple assembly of a telomeric dimeric G-quadruplex DNAzyme with Cu2+. The DNAzyme–catalyzed oxidation of 3,3′,5,5′-tetramethylbenzidine in the presence of H2O2 can generate a quantitative colorimetric signal, and the color change can be discerned by the naked eye. Compared with the reaction rate of the monomeric G-quadruplex–Cu2+ DNAzyme, the reaction rate of the dimeric G-quadruplex–Cu2+ (G2–Cu2+) DNAzyme is significantly accelerated, and the reaction rate gradually increases and then reaches a plateau with increasing number of TTA spacers. Herein, the G2–Cu2+ DNAzyme is chosen for the highly sensitive detection of DEF based on the DEF–Cu2+ complex–induced inhibition of its peroxidase-mimicking activities. The limit of detection (LOD) of DEF is achieved as low as 0.03 μM, and the linear range is from 0.05 to 1.2 μM. The proposed strategy exhibits excellent selectivity in the presence of potential interferents, such as metal ions and small molecules. Importantly, the G2–Cu2+ DNAzyme is further expanded to detect DEF in dispersible tablets and human serum samples. Overall, this G2–Cu2+ DNAzyme provides a simple, low-cost, and rapid platform for DEF detection. This novel strategy is the first example of DEF analysis by utilizing signal amplification technology based on the G-quadruplex DNAzyme and holds great potential for DEF quality control and therapeutic drug monitoring.

Highly integrated, self-powered and activatable bipedal DNA nanowalker for imaging of base excision repair in living cells

DNA walkers have attracted considerable attention in biosensing and bioimaging. Compared with the conventional single leg-based DNA walker, the bipedal DNA walker has remarkable advantages, with improved sensitivity and fast kinetics, and can work efficiently in a crowded cellular environment. However, most reported bipedal DNA walkers are powered by exogenous supplementation, and elaborate DNA sequence designs, auxiliary additives or extra carriers are often needed. A highly integrated bipedal DNA walker that can address robustness, sensitivity and consistency issues in a single system is highly desirable but remains a great challenge. We herein report a novel bipedal DNA nanowalker system through simple assembly of a DNA substrate, hairpin functionalized-AuNPs (AuNPs-H2), and a blocked Mn2+-dependent DNAzyme hairpin (H1) on degradable MnO2 nanosheets, which holds great potential for living cell operation. Highly integrated features enable the simultaneous delivery of core components of the bipedal DNA walker, including a walking track (AuNPs-H2), a walking strand (H1 cleaved by APE1), and a driving force (Mn2+-dependent DNAzyme cleavage) as a whole, thereby enhancing the control of the spatiotemporal distribution of these components at the intracellular target sites. The redox reaction between the MnO2 nanosheets and GSH inside the cells not only consumed the intracellular GSH to improve the biostability of the walking track but also generated abundant Mn2+ as a cofactor of the DNAzyme. As a proof of concept, the developed nanowalker was demonstrated to work efficiently for monitoring base excision repair (BER)-related human apurinic/apyrimidinic endonuclease 1 (APE1) in living cells, highlighting the great potential of the bipedal DNA nanowalker in biological systems.Graphical abstract

Simple and Efficient Laser-Induced Evaporation Assembly Method to Fabricate SERS Optical Fiber Probe for Detection of PAHs

Simple and Efficient Laser-Induced Evaporation Assembly Method to Fabricate SERS Optical Fiber Probe for Detection of PAHs

Amplification-free detection of Ascochyta blight in chickpea using a simple molecular beacon assay

Ascochyta blight is a major biotic stress that limits chickpea production globally. Fungicide application remains one of the effective control measures for the endemic spread. Due to the serious threat that synthetic fungicides pose to crop quality, early diagnosis of the pathogen is imperative. Whilst there have previously been several conventional lab-based diagnostic methods developed for early detection of Ascochyta rabiei, they require long assay times, specialised equipment and facilities, and trained personnel to process the samples. To overcome this challenge, a rapid amplification-free detection assay using a molecular beacon probe was developed. The method consists of a simple assembly assay that accurately detects pathogen within 30 min. The developed assay is species-specific and has a similar sensitivity level as conventional amplification-based methods. Although it is still a lab-based technique, considering the simplicity of the assay, it has a great potential to be developed further as a reliable in-field diagnostic device for early detection and quantification of fungal pathogen spores.

RNA Nanotechnology for Codelivering High-Payload Nucleoside Analogs to Cancer with a Synergetic Effect.

Nucleoside analogs are potent inhibitors for cancer treatment, but the main obstacles to their application in humans are their toxicity, nonspecificity, and lack of targeted delivery tools. Here, we report the use of RNA four-way junctions (4WJs) to deliver two nucleoside analogs, floxuridine (FUDR) and gemcitabine (GEM), with high payloads through routine and simple solid-state RNA synthesis and nanoparticle assembly. The design of RNA nanotechnology for the co-delivery of nucleoside analogs and the chemotherapeutic drug paclitaxel (PTX) resulted in synergistic effects and high efficacy in the treatment of Triple-Negative Breast Cancer (TNBC). The 4WJ-drug complexes were confirmed to have efficient tumor spontaneous targeting and no toxicity because the motility of RNA nanoparticles has been previously shown to enable these RNA-drug complexes to spontaneously accumulate in tumor blood vessels. The negative charge of RNA enables those RNA complexes that are not targeted to tumor vasculature to circulate in the blood and enter the urine through the kidney glomerulus, without accumulating in organs, therefore being nontoxic. Drug incorporation into RNA 4WJ can be precisely controlled with a defined loading amount, location, and ratio. The incorporation of nucleoside analogs into 4WJ only requires one step using nucleoside analogue phosphoramidites during solid-phase RNA synthesis, without the need for additional conjugation and purification processes.

Metagratings for underwater acoustic wavefront manipulation

Metagratings are flat periodic assemblies of small scatterers, engineered to achieve effects such as steering, beamforming, or absorption. They have recently received attention in both electromagnetism and acoustic fields. In this work, we report the design, modeling, and experimental characterization of metagratings to steer underwater acoustic wavefronts towards anomalous directions (i.e. not classically allowed by Snell-Decartes relationships) with high efficiency (close to 100%). They are build from simple assemblies of small brass cylinders, hold by 3D-printed plastic supports, and can redirect ultrasonic wavefronts either in reflection mode (when placed in front of a reflective surface like e.g. the water / air interface) or in transmission mode. Furthermore, we demonstrate how metagratings build from an asymmetrical pattern of multiple basic elements can achieve near perfect asymmetrical transmission: a wavefront incident from side of the structure is fully transmitted, while a similar wavefront incoming from the other side is fully reflected, achieving an acoustic one-way mirror effect. This work combine theoretical analysis, finite element modeling, and experimentation in water tanks to explore and demonstrate the potential of such metagratings for various applications in underwater acoustics, like communication, noise mitigation, and stealth.

Computational Design with Kurtboğaz: The Generation of Timber Structures with an Aggregative Design Algorithm

This paper investigates the form-finding capacity of the traditional timber-joint construction method, Kurtboğaz, aiming to explore new architectural forms and possibilities through computational design techniques to preserve vernacular construction methods and integrate them into contemporary architecture. It presents an Aggregative Design Algorithm (ADA) that creates different structures based on designer rules and simple assembly rules of Kurtboğaz, leading to unique emergent forms through random rule application. The paper also explores how reinforcement learning, a type of machine learning, can improve this design process through a theoretical framework. The study tries to use a rule-based generative algorithm to explore the modular and reconfigurable characteristics of the Kurtboğaz. The ADA enables random rule application, leading to diverse forms. However, several challenges may be encountered during the application of ADA because of its random aggregation, such as collision avoidance, structural integrity, boundary detection, and the optimization of structural parameters. The study suggests using Reinforcement Learning (RL) in the ADA framework to address these problems. Incorporating RL is anticipated to enable the algorithm to adaptively learn and optimize the form-finding process, enhancing the performance and applicability of the Kurtboğaz method in contemporary architectural practice. In the future, with this generative process described by the study, designs that create spatial differences with the help of walls, floors, and rooms on a human scale can be realized. The study also plans to explore the synergy between craftsmanship and digital fabrication in the future

Design of ternary GO@AgNPs@g-C3N4 membranes for efficient dye removals in integrated photocatalysis-filtration reactors

Photocatalytic composite membranes (PCMs), which integrate the high degradation efficiency of photocatalysts and the physical separation properties of membranes, have emerged as a promising technology for wastewater treatment. Herein, the ternary GO@AgNPs@g-C3N4 PCM was fabricated through a facile vacuum-filtration assembly of graphene oxide (GO), graphitic phase carbon nitride (g-C3N4), and silver nanoparticles (AgNPs) onto commercial mixed cellulose ester (MCE) substrates. The effects of g-C3N4 synthesized from different precursors and various metal nanoparticles on the performance of PCM were systematically investigated. Interestingly, results show the addition of AgNPs not only significantly improves the photocatalytic performance of PCMs but also enhances the mechanical adhesion between the active layer and the MCE substrate. The resultant PCMs exhibit outstanding photocatalytic performance, maintaining dye removal above 89% even after 25 consecutive cycles. Moreover, dye degradation pathways over the PCMs were investigated through free radical scavenging experiments and electron spin resonance characterizations. This simple assembly method results in a 3–12 times increase in flux compared to the layer-by-layer assembly method. Accordingly, our designed PCMs exhibit significant potential for wastewater treatment and water purification applications.

The Effect of Hyperconjugation and Hydrogen Bonding on the Conformers of Methylated Monosaccharides.

The conformational landscapes of four 1-O-methylated monosaccharides-methyl a-glucose, methyl b-glucose, methyl a-galactose, and methyl b-galactose-were characterized using jet-cooled broadband rotational spectroscopy, supported by density functional theory calculations. A newly designed, simple pulsed nozzle assembly was used to introduced the sugar samples into a jet expansion without thermal degradation, eliminating the need for a complex and expensive laser ablation system. Ten conformers were experimentally identified by assigning their rotational spectra, and the intricate methyl internal rotation splittings were analysed. Notably, methylation alters the directionality of intramolecular hydrogen bonding of a-galactose highlighting its impact on structural preference. Natural bond orbital, intrinsic bond strength, and non-covalent interaction analyses were conducted to explore the interplay between hydrogen bonding and hyperconjugation. A set of σ to σ* neutral hyperconjugative interactions were found to override a strong hydrogen bond, driving a preference for the gauche conformers.

Prominent cycling reversibility and kinetics enabled by CaTiO3 protective layer on Zn metal for aqueous Zn-ion batteries

Aqueous Zn-ion batteries (AZIBs) have received considerable attention owing to their various advantages such as safety, low cost, simple battery assembly conditions, and high ionic conductivity. However, they still suffer from serious problems, including uncontrollable dendrite growth, corrosion, hydrogen evolution reaction (HER) from water decomposition, electrode passivation, and unexpected by-products. The creation of a uniform artificial nanocrystal layer on the Zn anode surface is a promising strategy for resolving these issues. Herein, we propose the use of a perovskite CaTiO3 (CTO) protective layer on Zn (CTO@Zn) as a promising approach for improving the performance of AZIBs. The CTO artificial layer provides an efficient pathway for Zn ion diffusion towards the Zn metal because of the high dielectric constant (εr = 180) and ferroelectric characteristics that enable the alignment of dipole moments and redistribute the Zn2+ ions in the CTO layer. By avoiding the direct contact of the Zn anode with the electrolyte solution, the uneven dendrite growth, corrosion, parasitic side reactions, and HER are mitigated, while CTO retains its mechanical and chemical robustness during cycling. Consequently, CTO@Zn demonstrates an improved lifespan in a symmetric cell configuration compared with bare Zn. CTO@Zn shows steady overpotential (∼68 mV) for 1500 h at 1 mA cm−2/0.5 mA h cm−2, excelling bare Zn. Moreover, when paired with the V2O5-C cathode, the CTO@Zn//V2O5-C full battery delivers 148.4 mA h g−1 (based on the mass of the cathode) after 300 cycles. This study provides new insights into Zn metal anodes and the development of high-performance AZIBs.

Flexible and high-strength MXene/polyimide nanofiber aerogel membranes achieving infrared stealth through combined thermal control and low emissivity

The development of high-performance infrared stealth materials has been a long-standing goal for scientists. Despite their excellent performance, these materials are challenging to fabricate. In this work, a simple water immerse-stacking assembly process is employed to transform two-dimensional nanofiber membranes into three-dimensional aerogel membranes. Directional freezing from different directions induced varied orientations in the polyimide nanofibers (PINF), leading not only to unique anisotropic microstructures and thermal conductivities but also to synergistic enhancements in thermal insulation and mechanical properties. By vacuum-assisted filtration, MXene is embedded into the PINF membrane, resulting in a low emissivity of 0.283 and strong interlayer bonding of the MXene/PINF aerogel membrane without affecting the high and low-temperature resistance, the tensile strength, and the flexibility. Inspired by the art of origami, two types of MXene/PINF aerogel membrane bags are developed. When using one of the bags to cover an object at 130.2 °C, the thermal radiation temperature decreases to 28.9 °C. This study provides a promising approach for designing flexible, high-strength, and efficient infrared stealth composite materials, paving the way for further research and applications.

Carbon dot-loaded Fe3O4 as photonic pigments for multilevel anti-counterfeiting

Amorphous arrays assembled from colloidal microspheres are a way that obtains angle-independent structural colors. In order to obtain additional properties, colloidal microspheres, which are constituent units, can be modified with other materials. Here, we utilized the silane-functionalized carbon quantum dots (SiCDs) by incorporating them into the Stöber reaction to fabricate Fe3O4@SiO2/SiCDs nanospheres with a core-shell structure. Amorphous colloidal arrays (ACAs) were constructed on commercial printing paper using Fe3O4@SiO2/SiCDs nanoparticles as structural units by a simple permeation assembly. Macroscopically, the prepared ACAs exhibit the magnetic properties of Fe3O4, while under sunlight, they display bright, angle-independent structural colors. Under ultraviolet light, the array shows significant fluorescence. This enables the presentation of multidimensional information under varying magnetic and lighting conditions. By adjusting the thickness of the outer SiO2/SiCDs composite layer, the optical properties and magnetism can be controlled easily. Moreover, due to the strong light absorption capability and high refractive index of Fe3O4, the digital patterns constructed with Fe3O4@SiO2/SiCDs nanospheres demonstrate excellent multi-level anti-counterfeiting characteristics, even under water exposure. The magnetic properties of Fe3O4@SiO2/SiCDs nanospheres, along with their distinct display characteristics under different optical environments, suggest their wide applicability in the fields of multifunctional anti-counterfeiting pigments, bioimaging, and sensing displays.

Comparative study on the bending moment capacity and stiffness of innovative and traditional furniture corner joints

ABSTRACT This study compares the bending moment capacity under compression and bending moment capacity under tension values of eight selected structural furniture joints. Specimens (type L) with a dimension of 150 × 150 × 366 mm were made from three-layer, 18 mm thick particleboard. The corner joints were tested in angular bending in compression and tension. Both classic and new joining elements (plastic cam, zinc cam, one-part plastic connector, screw cam, plastic connector with euroscrew, and birch dowel pre-glued) for the simple assembly of furniture were used in the study. Cam joints with wooden dowels can withstand high stress. There are only minimal differences between joints made of plastic or zinc cams with dowels. If birch dowels with an adhesive coating are added to the plastic joint from sample with plastic connector with euroscrew, this joint will reach 126% higher values in angular bending tests – compressive stress.

Assessing the performance of three experimental methods to investigate air path inside wall assemblies

Air leakages in buildings’ envelopes can lead to an over-consumption of energy and to additional issues such as moisture damage and poor indoor environment. The leakage air flow rate is usually assessed at the building scale using a pressurization test and leakage locations are commonly detected by infrared thermography or smoke. However, little is known about the air paths within wall assemblies, despite the need for detailed experimental data to validate numerical models for the coupled heat, moisture and pollutants transfers. One of the reasons is the difficulty to find adapted and robust experimental methods.In this paper, three experimental laboratory approaches are tested on simple light-wall assembly configurations: the implementation of three-dimensional grids of thermocouples and relative humidity sensors within the wall, and the use of a micro-particle tracer. The results are compared with each other as well as with numerical simulations.It was found that thermocouple grid has limited intrusiveness, good accuracy and response time but results are subject to flow fluctuations. Moreover, heat capacity and conductive transfer within materials complicate the correlation between heat and air transfers. Humidity sensors grid avoids the latter issue but is intrusive, overestimating air dispersion. The micro-particle tracer has the advantage of being non-intrusive and less impacted by flow fluctuations but its ability to track the air flow is strongly linked with the insulation filtration properties and the flow velocity. Overall this method seems to provide the best results but it is also the most complex and time-consuming one.

Highly matched electrode for all-solid-state sodium-ion fiber hybrid supercapacitor with wide temperature and high energy density

In order to solve the kinetic mismatch problem of hybrid supercapacitors, a simple and effective assembly technology for wide temperature all-solid-state sodium-ion fiber hybrid supercapacitor is proposed based on anode and cathode with optimal volume capacity ratio and complementary potential windows. Ti3C2Tx fiber anode is produced by wet spinning in acetic acid bath. It reveals an excellent volume capacity of 406 F cm−3, good cycle stability of 90 % retention in 1 M NaClO4 electrolyte, high conductivity of 3303 S cm−1, and tensile strength of 80 MPa. NaV3O8/rGO (NVO/rGO) fiber cathode is obtained by wet spinning and hydrothermal treating, exhibiting high matched volumetric capacitance and improved rate performance. Moreover, a wide temperature all-solid-state sodium-ion fiber hybrid supercapacitor (PVA EGHG NVO/rGO//Ti3C2Tx AFSIC) is assembled using polyvinyl alcohol ethylene glycol hydrogel (PVA EGHG) as separator and electrolyte. The AFSIC shows an outstanding volumetric specific capacitance of 76 F cm−3 at 0.1 A cm−3, and a maximum volumetric energy density of 30.6 mWh cm−3 at a power density of 83.2 mW cm−3. In addition, it can be bend to diverse degrees without significant change in its electrochemical performance. In addition, the AFSIC exhibites exceptional capacitance and outstanding flexibility in a wide temperature range of −40 to 60 °C, showing that the PVA EGHG NVO/rGO//Ti3C2Tx AFSIC has wide prospect in the area of wearable electronic components.

Assembly of primary secondary amine over magnetic graphitized carbon black material for selective cleansing of sample matrices

Pigments and organic acids are among the most common impurities in complex sample matrices. Their presence in the samples often interferes with the detection of trace analytes. This study aimed to design and develop magnetic materials (GCB/Fe3O4-PSA) for the efficient purification of organic acids and pigment impurities in sample matrices. We employed the acid modification method to enhance the modification of magnetic Fe3O4 by the primary secondary amine adsorption group (PSA), effectively boosting its adsorption performance. This modification technique not only retains the inherent adsorption characteristics of Fe3O4 but also avoids the irreversible damage to Fe3O4′s own adsorption by traditional grafting methods. Subsequently, Fe3O4-PSA and graphitized carbon black (GCB) were combined through a simple physical assembly method to prepare GCB/Fe3O4-PSA, which was used for the purification of pigments and organic acids in complex matrices. During the purification process, GCB/Fe3O4-PSA can be rapidly magnetically separated. After six reuses, the adsorption performance remains above 80 %, fully demonstrating the rapid purification ability and reusability potential of GCB/Fe3O4-PSA. Compared with unmodified Fe3O4, GCB/Fe3O4-PSA significantly enhanced the purification effect of complex matrices. Its adsorption capacities for chlorophyll and ascorbic acid increased by 276.9 % and 263.9 % respectively. After combining with the GCB/Fe3O4-PSA purification material, cathinones in complex matrix samples (tea, apples, carrots) were determined using UPLC-MS/MS. The recoveries in spiked samples ranged from 96.35 % to 104.17 %, with the RSDs < 3.02 %. Simultaneously, characterization methods such as SEM, FTIR, XRD, VSM, XPS, and BET were used to study the surface structure and chemical composition of GCB/Fe3O4-PSA. The above results highlight the outstanding performance of GCB/Fe3O4-PSA in the efficient purification of organic acids and pigments in complex matrices and also show its considerable application potential in the pretreatment of complex matrix samples.

Scheduling in a Simple Assembly Robotics Cell to Minimize Earliness and Tardiness

Background: Robotics Assembly Cells (RAC) have been designed to meet the flexibility requirements demanded by today's globalized market. The objective is to manufacture a vast variety of products at a low cost, which requires equipment with a high level of flexibility, such as robots. The need to schedule a great variety of jobs in an RAC is a very relevant issue, as efficiency and productivity depend on the sequence in which jobs are scheduled. Studies around this matter have developed models with analytical and heuristic approaches, as well as simulation methods and genetic algorithms, seeking to improve performance measures based mainly on time, utilization, and costs. Method: The purpose of this article is to formulate an exact mathematical model using mixed-integer linear programming (MILP) to optimize small scheduling problems. The objective is to minimize the measure of performance related to the tardiness and earliness of jobs. This optimization aims to mitigate the effects of delays in product deliveries, queue times, and work-in-process inventory in subsequent processes. Doing so facilitates adherence to agreed-upon delivery deadlines and prevents bottlenecks in the assembly cell. Results: The proposed mathematical model generates optimal solutions to the job scheduling problem in the assembly cell, which serves as a case study. This addresses the need to minimize tardiness to meet delivery deadlines or minimize earliness while avoiding an increase in work-in-process inventories. The model ensures that optimal scheduling decisions are made to optimize both delivery performance and inventory levels. Conclusions: Due to the NP-hard complexity of the scheduling problem under study, the proposed mathematical model demonstrates computational efficiency in solving scheduling problems with fewer than 20 jobs. The model is designed to handle such smaller-scale problems within a reasonable computational time frame, considering the inherent complexity of the scheduling problem.