Vacuum Techniques Research Articles

Association between levator ani muscle avulsions and technique of vacuum extraction - a prospective exploratory study.

Trauma of the levator ani muscle in the form of partial or complete avulsions is common after vaginal births, especially after vaginal-operative births. As there is little information available regarding associations between the technique of vaginal-operative births and levator ani muscle trauma, we aimed to evaluate the association between the process of vacuum extraction and the occurrence of levator ani muscle trauma. As part of a prospective cohort study at the University Hospital of Zurich between March 2017 and April 2019, we sub-analysed vacuum extractions in nulliparous women with singletons in vertex presentation ≥36+0 gestational weeks. We evaluated their pelvic floor for partial and complete levator ani muscle avulsions using translabial ultrasound 6–10 weeks postpartum and calculated the association of the vacuum procedure itself, along with other fetal, maternal and obstetrical characteristics, with levator ani muscle trauma. Levator ani muscle trauma was present in 17 (34.7%) out of 49 women. There were no associations between the different factors evaluated and levator ani muscle trauma in vacuum-assisted births, except that the levator ani muscle group had insufficient uterine contractions. We found no fetal, maternal or obstetrical characteristics or parameters of vacuum technique that were associated with the occurrence of levator ani muscle trauma after vacuum extraction, except for insufficient uterine contractions. Nevertheless, there might be influencing factors that have not yet been evaluated, or are not easily accessible for evaluation, like the adaptations of the fetus inside the birth canal and within the hiatus of the levator ani muscle, and the adaptations of the birth canal to the fetus passing through. This should be the subject of further research with a sample size adequately powered to answer this question properly. (Trial registration number: BASEC-Nr.2016-00908.) &nbsp.

Synthesis, Materials and Chemistry of Alternative Solid State Electrolyte Films for Batteries

Next generation of energy storage devices may largely benefit from fast and solid Li+ ceramic electrolyte conductors to allow for safe and efficient batteries and fast data calculation. For those applications, the ability of Li-oxides to be processed as thin film structures and with high control over Lithiation and phases at low temperature is of essence to control conductivity. In particular, Li-garnet structures are attractive due to their fast transfer properties and safe operation over a wide electrochemical stability range for batteries.In the first part we focus on low temperature processing of Li-garnet thin films and nanostructures. Examining the structure-Li transport in solid state and asking the provocative question: How do Li-amorphous to crystalline structures conduct? How to alter processing of Li-oxide films to compensate for the challenge that most of Lithium phases lead to sluggish transport and hard phase stabilization? Bringing down battery solid electrolyte processing temperature and decreasing form factor opens new opportunities in battery design and new doors to give more functions for similar material classes for neuromorphic computing.Through the talk, we focus on new processing opportunities to Lithiate thin film structures in crystalline state and to assure cubic and fast conduction on the example of Li-garnet for thin film form using some active Lithiation strategies at film deposition1-3. For this we will review the field of thin film processing and introduce to new processing routes based on vacuum and wet-chemical techniques to control various strategies of Lithiation and phase evolution. Excitingly, one has the opportunity for Li-garnet solid state conductors to not only synthesize crystalline structures, but also amorphous films in various frozen-in states4. Insights on degree of amorphous to crystalline Li-garnet thin films are presented based on model experiments, incl. JMAK and TTT-diagram analysis of Li-garnet structure types. Dependent on either a vacuum or wet-chemical based method chosen the phase evolution differs when synthesizing the glass states, with significant impact on condensation and Li-transport5-6. We find that the different amorphous structures that Li-garnets are no Zachariasen glasses as they violate several of Zachariasen rules by text book: These amorphous Li-garnets differ therefore significantly from LIPON but have a wider room to arrange the higher coordinated polyhedral, network former and builders. In amorphous garnets there is room for manipulation in densification and Li-transport and one may potentially profit from high stability window to design batteries with no grain boundaries at the Li electrolyte interface.In the last part of the talk we will discuss novel low temperature synthesis strategies to define future solid state batteries for low costs and suitability to enter mass manufacturing from a ceramicists perspective.Collectively, the insights on solid state energy storage provide evidence for the functionalities that those Li-materials can have in the future. The challenges are deeply connected to low temperature processing and design of structure-transport properties, however, solving those allows us to define novel solid state battery architectures.

Understanding the Electrocatalytic Solid-Liquid Interface: The Early Years of the Więckowski University of Illinois Research Group

Andrzej Więckowski was an Assistant/Associate Professor of Chemistry at the University of Illinois Urbana-Champaign from 1985 to 1996 and a Full Professor from 1996 to 2012. Andrzej had a unique ability to attract students to his research group due to his infectious enthusiasm, boundless energy, and excitement for science and cutting-edge experimental approach. This talk will focus on the early years of Andrzej’s tenure at the University of Illinois and his pioneering research in probing the composition and structure of electrocatalytic solid-liquid interfaces using ultra-high vacuum techniques (Figure 1), radiochemistry, and electrochemical nuclear magnetic resonance spectroscopy.Figure 1. (left) The first ultra-high vacuum instrument in the Andrzej Więckowski University of Illinois, Urbana-Champaign research group and (right) Andrzej, 1987. Figure 1

(Invited) Advancement of Low Temperature Ceramic Synthesis for Solid State Battery Components and Cells – a Personal Love Story

Next generation of energy storage devices may largely benefit from fast and solid Li+ ceramic electrolyte conductors to allow for safe and efficient batteries and fast data calculation. For those applications, the ability of Li-oxides to be processed as thin film structures and with high control over Lithiation and phases at low temperature is of essence to control conductivity. Through this presentation we review the field from a new angle, not only focused on the classics such as Li-ionic transport and electrochemical stability window for Li-solid state battery electrolytes, but focusing on opportunities and challenges routes in thermal and ceramic processing of the components and their assemblies with electrodes. Also, we will carefully review and give perspectives on the role of solid state battery ceramic strategies for the electrolyte on the electrode interfaces and towards charge transfer and vs. current densities. In other words, it will be a little ceramicist (own) love story on the good and the evil we can design by smart ceramic design at the interfaces originating by the very first choices made in the electrolyte ceramic structure and material design. In the second part of the talk we will discuss new opportunities on low temperature processing of solid state electrolyte ceramics that do not technically require “classic sintering” and avoid prior particle calcination; instead demonstrating opportunities to use liquid based direct densification routes and vacuum techniques to design solid electrolytes and grafting interfaces to new hybrid and solid state battery prototypes targeted at processing below 700C for all parts. Collectively, the insights on solid state energy storage provide evidence for the functionalities that those Li-solid state material designs can have for cost and mass manufacturable solid state and hybrid battery prototypes.

Perspectives of chalcopyrite-based CIGSe thin-film solar cell: a review

Solar photovoltaic (PV) is empowering, reliable, and ecofriendly technology for harvesting energy which can be assessed from the fact that PV panels with total electricity generation capacity of 505 GW have been installed by the end of 2018. Thin-film solar cells based on copper indium gallium selenide (CIGSe) are promising photovoltaic absorber material owing to an alternative to crystalline silicon (c-Si)-based solar cells because of the huge potential for low-cost solar electricity production with minimal usage of raw materials. The efficiency record of 23.4% was achieved recently in CIGSe solar cells, which was comparable to c-Si solar cells (27.6%). The manufacturing cost of $0.34/W is expected for 15% efficient CIGSe module. The present review article discusses the perspectives of CISe/CIGSe-based thin-film solar cells with the focus on absorber material. Different vacuum and non-vacuum techniques for fabricating these materials are discussed along with the operation of solar cells and their manufacturability. The working mechanism of CIGSe solar cells with the characteristic features of the open-circuit voltage and current density as well as the factors influencing the efficiency in different fabrication techniques are reviewed. Moreover, some strategies toward the improvement of solar cells performance contemplating modified deposition are reviewed. Furthermore, how these strategies can be executed in order to make it cost effective methods is also discussed in detail. Prevailing constrictions for the commercial maturity are deliberated, and future perspectives for improvement at lab as well as industrial scalabilities are outlined.

An affordable method to produce CuInS2 ‘mechano-targets’ for film deposition

We report on the room temperature, simple and cheap preparation by mechano-synthesis of polycrystalline targets of complex sulphide semiconductors, namely CuInS2 (CIS), to be used for film deposition in physical vacuum techniques such as PLD, sputtering or LT-PED. The sulphur (S)-based targets usually require expensive high pressure equipment to compensate the high S vapour pressure; nevertheless they are indispensable for the deposition of high band-gap semiconductor materials. The comparison of CIS films grown by mechano-synthesis and by commercial targets demonstrates similar material quality, making the mechano-synthesis a viable solution in the fabrication of high band-gap, S-based targets of complex chalcogenides.

Experimental study on the thermal volatilization and condensation of zinc at 10 Pa and 200 Pa

The thermal volatilization and condensation of zinc at different heating temperatures were investigated at 10 Pa and 200 Pa. The vacuum technique is beneficial for the volatilization of metallic zinc, and the zinc volatilization is affected by heat transfer and mass transfer. The effect of zinc partial pressure on the nucleation is analyzed in terms of the average number of collisions of molecules. When the system pressure is 10 Pa, the range of the condensation temperature of (623–503 K) does not change with the change of the heating temperature, which is consistent with the pressure on the average number of collisions of zinc molecules per unit time. In addition, when argon gas is introduced into the system to keep the pressure at 200 Pa, the condensation temperature ranges becomes different and the heating temperature is linear with the condensation initiation temperature. The condensation mechanism of condensed products is different at different axial distances of 1023 K under 10 Pa and 200 Pa. The morphology and the particle size of the products are different under different system pressures, respectively.

Vacuum preloading, an alternative soft ground improvement technique for a sustainable development

Preloading with soil surcharging in combination with prefabricated vertical drain is one of the common methods used in improving high compressibility and low shear strength of soft soils, particularly in improving very soft to soft clay. One of the main issues of this technique is it requires a high volume of backfill material to apply the surcharging, hence, whenever the availability of the backfill material is scarce or remote, it becomes expensive. In such a case, vacuum preloading becomes one of the best options to be applied in alleviating the high compressibility and low shear strength of the soft clay layers. This vacuum technique also helps to create a sustainable environment as it omits the needs of a high volume of backfill material. Therefore, no hills cutting or ground excavation is required. This paper presents the difference between surcharging and vacuum preloading methods, the working principle, and installation of vacuum preloading. Case histories in improving the soft soils of in low land areas, a large residential located on high ground about 700m from sea level, and a highway construction projects are presented. The case histories revealed that proper application of vacuum preloading could effectively improve soft clays, be in a low land area or high ground area. The depth improved can reach as deep as 25m.

Laminated Perovskite Photovoltaics: Enabling Novel Layer Combinations and Device Architectures

AbstractHigh‐efficiency perovskite‐based solar cells can be fabricated via either solution‐processing or vacuum‐based thin‐film deposition. However, both approaches limit the choice of materials and the accessible device architectures, due to solvent incompatibilities or possible layer damage by vacuum techniques. To overcome these limitations, the lamination of two independently processed half‐stacks of the perovskite solar cell is presented in this work. By laminating the two half‐stacks at an elevated temperature (≈90 °C) and pressure (≈50 MPa), the polycrystalline perovskite thin‐film recrystallizes and the perovskite/charge transport layer (CTL) interface forms an intimate electrical contact. The laminated perovskite solar cells with tin oxide and nickel oxide as CTLs exhibit power conversion efficiencies of up to 14.6%. Moreover, they demonstrate long‐term and high‐temperature stability at temperatures of up to 80 °C. This freedom of design is expected to access both novel device architectures and pairs of CTLs that remain usually inaccessible.

Transmission spectra of copper, aluminum and chalcopyrite – based thin nanostructured films prepared by gas discharge technique

Purpose. At present, alloys of СuIn(Sb)S2(Se2) from chalcopyrite class are perspective materials for solar cells batteries. This is caused by their high absorption coefficient in a wide spectral region as well as high light resistivity of layer coverings. Laser sputtering permit (allow) to obtain stoichiometric thin films of chalcopyrite but the yield of largearea covering is low, and a process of their fabrication is expansive due to high cost of laser and vacuum technique used. Reasonable, exploiting of simpler gas-discharge techniques of chalcopyrite synthesis for photovoltaic solar cells convertors is actual and important. At the same time, optical characteristics of chalcopyrite layers synthesized from over-constrained plasma are not considered. Results of optical absorption spectra for СuInSe2 layers at glass (quarts) substrate, obtained at different gas ambient pressure of over-constrained nanosecond plasma discharge. Methods. Methods and technique for thin films-based coper oxides, aluminum and chalcopyrite Nanostructures obtained in air and inert gases are considered in details for ecotone mechanism of sputtering are considered. For these samples optical transmit ion were investigated in 200 – 800 nm range. Results. Transmission spectra for samples on glass substrates in 200 – 500 and 350 – 800nm, correspondingly, were obtained. Gas ambient – air and argon – at 1 atm pressure for all electrode materials. Layers were obtained by abovementioned technique. We start to register transmition for wave-lengths above 300 nm. For copper-based films sputtered in argon observed maximal transmition. Probably this is nanostructured coper films. Minimal transmition is inherent for aluminum- and chalcopyrite films. The strong absorption of light by chalcopyrite films in the region of 200-800 nm indicates that when the films of chalcopyrite are sprayed with a gas-discharge method, they repeat the stoichiometry of the chalcopyrite electrodes. Conclusions. Pulsed gas-discharge method for copper film preparation is vividly perspective for transparent electrodes applications. Films of chalcopyrite are characterized by strong absorption in the range of the spectrum of 200 – 800 nm, which is promising for their applications in photovoltaics.

Structural and Optical Properties for Nanostructure (Ag2O/Si & Psi) Films for Photodetector Applications

Ag2O (Silver Oxide) is an important p-type (in chasm to most oxides which were n-type), with a high conductivity semiconductor. From the optical absorbance data, the energy gap value of the Ag2O thin films was 1.93 eV, where this value substantially depends on the production method, vacuum evaporation of silver, and optical properties of Ag2O thin films are also affected by the precipitation conditions. The n-type and p-type silicon substrates were used with porous silicon wafers to precipitate ±125 nm, as thick Ag2O thin film by thermal evaporation techniques in vacuum and via rapid thermal oxidation of 400oC and oxidation time 95 s, then characterized by measurement of XRD, optical properties and scanning electron microscopy properties (SEM). Maximum value of photo response obtained from p-Ag2O/p-PS/Si photodetector results revealed two peak sat 600 nm and 800 nm. According to the x-ray diffraction four peaks appear, (111), (200), (110) and (311) Ag, respectively, (polycrystalline film) and lattice constant of (4.077 Å). Also the results showed a sharp increasing in the absorption-wave length plot of Ag2O film at UV and IR regions. The accumulation of the stars-like are semi-regular of the Ag2O nanocrystals on the surface of p-type PS and the other diffuse inside the pores in a nearly uniform distribution with a different grain size on the surface. The results of the dislocation density and strain are decreased with the grain size increasing.

Microwave properties of Mg–Zn ferrite deposited by the thermal evaporation technique

Spinel ferrite samples of Mg0.6Zn0.4Fe2O4 were fabricated using the sol-gel technique. Thermal evaporation in the vacuum technique was used to deposit an (850, 350) ± 30 nm thick layer of this ferrite powder on the glass substrates. The results of XRD, SEM, and AFM showed that the prepared thin films are polycrystalline and nano-sized, with homogeneous particle size and good distribution. The porosity of the films was small, and the occurrence of microstrain on the crystals was observed because of the sintering temperature.Ferrite's thin-film thickness effect on the microwave properties was studied using the Vector Network Analyzer (VNA) in the X-band frequency range of 8–12.5 GHz.The microwave properties increased with increasing film thickness due to the spin-spin interaction process between the incidence waves and the spin-wave. High stability of the reflection, absorption and very high proportions for the two thicknesses is obtained. The resonance peaks for the thin films of spinel ferrite appeared at frequencies of 8.2, 8.4, 8.6, 9.2, 9.8, 10.0, 10.2, 11.2, 11.4, 12.01, and 12.2 GHz.

Complexes of end-functionalized polystyrenes carrying amine end-group with transition metals: association effects in organic solvents

Linear end-functionalized polystyrenes of different molecular weights bearing amino end-group (NPS) were synthesized by anionic polymerization high vacuum techniques. The polymers were exposed to copper and iron salts (CuCl2.2H2O and FeCl3.6H2O) to form complexes with specific metal/amino molar ratios. The thermal stability of these complexes was studied by Thermogravimetric Analysis (TGA) and Differential Thermogravimetry (DTG), whereas their solution behavior was studied by Low Angle Laser Light Scattering (LALLS), Dynamic Light Scattering (DLS) and dilute solution Viscometry. Extended aggregation phenomena of these complexes were observed in organic solvents. The association behavior was influenced by the molecular weight of the polymer chain, the metal/amine group molar ratio, the chemical nature of the metal and the polarity of the solvent. A complex situation was revealed by DLS showing the existence of equilibrium between aggregates and clusters. Under the influence of shear forces applied in the capillary tube of the viscometer the clusters are disrupted.

Surface charge density of triboelectric nanogenerators: Theoretical boundary and optimization methodology

Although high charge densities of triboelectric nanogenerators (TENG) were achieved by working in high vacuum or charge pumping techniques in atmosphere, owing to their complex structure and/or stability issues, it still remains a great challenge and necessity to directly obtain the high charge density directly through triboelectrification effect in atmosphere. Here, a basic theory about the limitation factors of surface charge density is comprehensively rebuilt through analytical mathematical derivation of the limitation equation. As a result, high surface charge density can be obtained directly by a new optimization methodology, i.e. using thin dielectric layer, which is demonstrated by the designed contact-separation model TENG and sliding model TENG. In addition, the theoretical models of charge decay and charge accumulation during triboelectrification process were built. This work provides not only a new facile and universal optimization methodology for TENG, but also a new insight in the triboelectrification process, both of which will prompt the applications of TENG ranging from powering electronic devices to harvesting large-scale blue energy.

3D Organic Nanofabrics: Plasma-Assisted Synthesis and Antifreezing Behavior of Superhydrophobic and Lubricant-Infused Slippery Surfaces.

Herein, we present the development of supported organic nanofabrics formed by a conformal polymer-like interconnection of small-molecule organic nanowires and nanotrees. These organic nanostructures are fabricated by a combination of vacuum and plasma-assisted deposition techniques to generate step by step, single-crystalline organic nanowires forming one-dimensional building blocks, organic nanotrees applied as three-dimensional templates, and the polymer-like shell that produces the final fabric. The complete procedure is carried out at low temperatures and is compatible with an ample variety of substrates (polymers, metal, ceramics; either planar or in the form of meshes) yielding flexible and low solid-fraction three-dimensional nanostructures. The systematic investigation of this progressively complex organic nanomaterial delivers key clues relating their wetting, nonwetting, and anti-icing properties with their specific morphology and outer surface composition. Water contact angles higher than 150° are attainable as a function of the nanofabric shell thickness with outstanding freezing-delay times (FDT) longer than 2 h at -5 °C. The role of the extremely low roughness of the shell surface is settled as a critical feature for such an achievement. In addition, the characteristic interconnected microstructure of the nanofabrics is demonstrated as ideal for the fabrication of slippery liquid-infused porous surfaces (SLIPS). We present the straightforward deposition of the nanofabric on laser patterns and the knowledge of how this approach provides SLIPS with FDTs longer than 5 h at -5 °C and 1 h at -15 °C.

Preliminary research for long lasting self-healing effect of bacteria-based concrete with lightweight aggregates

A typical phenomenon in concrete structures is crack formation. Shrinkage cracks may appear in early stage of concrete. In late age cracks may appear due to process of serviceability and external weather conditions. Larger cracks interfere structural integrity, micro-cracks may result in durability problems as increase of water absorption, which results in concrete degradation and reinforcement corrosion. Manual maintenance of the concrete structure is costly and labour consuming; therefore, functionality of self-healing phenomenon of concrete structures has been inspected.In this study self-healing phenomenon of bacteria-based concrete has been investigated. Calcium lactate and yeast medium with spore-forming alkaliphilic bacteria Bacillus Lentus have been chosen. Bacillus Lentus spores with medium were integrated (by using vacuum technique) into expanded clay granules (LECA) with a size of 2-4 mm. Direct addition of bacteria (without immobilization) in concrete limits the survival of bacteria from 1 to 2 months. In this study, to increase viability of bacteria at high pH media in concrete and thus the time-related functionality of self-healing agents, bacteria were immobilized in LECA.The mechanism of crack healing in bacteria-based concrete presumably occurs through metabolic conversion of calcium lactate to calcium carbonate. The influence of bacteria on the mechanical and physical properties of samples was estimated after 28 days and after 6 years. From the results obtained, it can be concluded that concrete samples with Bacillus Lentus showed an increase of 22% in compressive strength compared to the reference sample.The main task of this scientific research is to identify, if self-healing phenomenon happens for the samples, which are 28 days old and for samples which are 6 years old.Results from the optical investigation showed that self-healing phenomenon (after 14 days of healing) has occurred for all samples and cracks in concrete were partly closed with calcium carbonate.

Atomic Force Microscopy of Proteins.

Atomic force microscopy (AFM) enables imaging of surface-deposited proteins and protein structures under physiological conditions, which is a benefit compared to ultra-high vacuum techniques such as electron microscopy. AFM also has the potential to provide more information from the phase in tapping mode or from functional AFM modes. The sample preparation, probe selection, and imaging conditions are crucial for successful imaging of proteins. Here we give a detailed account of the steps toward imaging of soft samples in both air and liquid along with the basic theory underpinning these details.

Epitaxial, electro‐optically active barium titanate thin films on silicon by chemical solution deposition

AbstractRecent progress in the integration of BaTiO3 thin films with silicon has shown great promise for the development of on‐chip photonic devices. However, the highest performing thin films in the literature are deposited by costly and/or complex vacuum techniques. In this study, epitaxial BaTiO3 thin films are deposited on thin SrTiO3 template layers on Si(001) from an alkoxide‐based chemical solution under atmospheric conditions and yield an effective Pockels coefficient of 27 ± 4 pm/V for an ~85 nm film. Film crystallinity, microstructure, and defect nature are examined by X‐ray diffraction and high‐resolution transmission and scanning electron microscopy techniques and discussed within the context of the growth method as well as the observed electro‐optical response.

Optical and electronic properties of high quality Sb-doped SnO2 thin films grown by mist chemical vapor deposition

Transparent Sb-doped epitaxial SnO2 (101) thin films were grown via mist chemical vapor deposition, a nonvacuum solution-based technique that involves the gas-assisted transport of ultrasonically-generated aerosols from simple aqueous Sn and Sb precursors. The electrical properties (at 300 K) of the resulting films could be varied from insulating to semimetallic via Sb doping, with a minimum resistivity of 8×10−4Ωcm, carrier concentrations up to 3.93×1020cm−3, and a maximum mobility of 48.1±0.1cm2V−1s−1, results similar to those achieved using molecular beam epitaxy and other more-sophisticated high vacuum techniques. Secondary ion mass spectrometry and Hall effect measurements revealed that 14% of Sb in the precursor solution incorporates into the Sb:SnO2 films, with almost all the Sb atoms forming shallow substitutional donors on the Sn-site. The increase in the carrier concentration with Sb doping produced a Burstein-Moss shift of the optical gap of 0.49 eV, without significantly reducing the more than 90% transparency of the films in the visible region. X-ray photoemission spectroscopy (hν=1486.6eV) showed an asymmetric Sn3d5/2 core-level emission characterized by a carrier concentration-dependent peak splitting. This effect was modeled in terms of the creation of an intrinsic plasmon loss satellite from which a conductivity effective electron mass of (0.49±0.11)me was determined.

Effect of drying techniques on color and bioactive potential of two commercial edible Indonesian seaweed cultivars

Seaweeds (Kappaphycus alvarezii and Sargassum duplicatum) are potentially rich sources of bioactive compounds and functional constituents that are used in food applications. Sun, oven, vacuum, and freeze-drying techniques are commonly used seaweed drying techniques and could be classified as cheap (sun and oven) and expensive (vacuum and freeze) drying techniques based on ovens’ market price. Therefore, the study was designed to investigate the effect of cheap (sun and oven) and expensive (vacuum and freeze) drying techniques based on color and antioxidant potential of K. alvarezii and S. duplicatum using phenolic and antioxidant assays. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were employed to discriminate the drying techniques by instrumental color analysis. The results revealed that oven-dried seaweed extracts exhibited higher levels of phenolic (0.30 to 0.36 mg GAE g−1) and antioxidant potential (3.59 to 79.68%). PCA and HCA discriminated the drying techniques into two well-defined groups/clusters I (oven, vacuum, and freeze-drying) and II (sun drying) and revealed higher ΔE values of sun-dried seaweed samples, which was interpreted as color was preserved using drying techniques of cluster I. Overall, oven, vacuum, and freeze-drying techniques reported similarities in color characteristics and could be an alternate drying technique to preserve the color of seaweed cultivars. Therefore, oven drying technique is recommended due to low cost (compared with vacuum and freeze-drying) and an affordable alternative to sun drying, the preferred technique in fishing communities of low-and-middle-income countries, for the development of seaweed-enriched functional foods.