Terephthalate Research Articles

Selective Modification of the Product Profile of Biocatalytic Hydrolyzed PET via Product-specific Medium Engineering.

Over the past years, enzymatic depolymerization of PET, one of the most widely used plastics worldwide, has become very efficient leading to the end products terephthalic acid (TPA) and ethylene glycol (EG) used for PET re-synthesis. Potent alternatives to these monomers are the intermediates BHET and MHET, the mono- and di-esters of TPA and EG which avoid total hydrolysis and can serve as single starting materials for direct re-polymerization. This study therefore aimed to selectively prepare those intermediates through reaction medium engineering during the biocatalytic hydrolysis of PET. After a comparative pre-screening of 12 PET-hydrolyzing enzymes, two of them (LCCICCG, IsPETasewt) were chosen for detailed investigations. Depending on the reaction conditions, MHET and BHET are predominantly obtainable: (i) MHET was produced in a better ratio and high concentrations at the beginning of the reaction when IsPETasewt and 10% EG was used; (ii) BHET was produced as predominant product when LCCICCG and 25% EG was used. TPA itself was nearly the single product at pH 9.0 after 24h due to the self-hydrolysis of MHET and BHET under basic conditions. Using medium engineering in biocatalytic PET-hydrolysis, the product profile can be adjusted so that TPA, MHET or BHET is predominantly produced.

Selective Degradation of Polyethylene Terephthalate Plastic Waste Using Iron Salt Photocatalysts.

Plastic pollution poses a significant challenge to environmental conservation. Efficient recycling of plastic is a key strategy to address this issue. Polyethylene terephthalate (PET), commonly found in plastic bottles, represents a substantial portion of plastic waste. Consequently, the efficient degradation and recycling of PET is crucial for the sustainable development of society. However, the implementation of methods for PET depolymerization and recycling typically necessitates alkaline/acidic pre-treatment and significant energy input for heating. Here, we propose a gentle, and highly efficient photocatalysis approach for selectively degrading PET plastic waste into terephthalic acid (TPA) in high yield (up to 99%) using cost-effective iron salts. Notably, this method achieved excellent selectivity with high TON and TOF values, applying oxygen or air as environmentally friendly oxidants. In addition, the solvent can be recycled without compromising the TPA yield, and large-scale reactions can be performed smoothly.

Synthetic studies on the tetrasubstituted D-ring of cystobactamids lead to potent terephthalic acid antibiotics

Novel scaffolds for broad-spectrum antibiotics are rare and in strong demand because of the increase in antimicrobial resistance. The cystobactamids, discovered from myxobacterial sources, have a unique hexapeptidic scaffold with five arylamides and possess potent, resistance-breaking properties. This study investigates the role of the central D-ring pharmacophore in cystobactamids, a para-aminobenzoic acid (PABA) moiety that is additionally substituted by hydroxy and isopropoxy functions. We varied the two oxygenated substituents and replaced both amide connectors with bioisosteres. Synthetic routes were developed that included metal-mediated aromatic functionalization or heterocycle formations, leading to 19 novel analogues. The antibiotic efficacy of all analogues was determined against bacteria from the ESKAPE pathogen panel. While the replacement and the repositioning of hydroxy and isopropoxy substituents was not advantageous, exchanging PABA by terephthalic acid amides led to the highly potent analogue 42 with broad-spectrum activity, insensitivity towards AlbD-mediated degradation and promising pharmacokinetic properties in mice. The study highlights the steep structure-activity relationships in the tetrasubstituted D-ring and a surprisingly favorable reversion of the amide connecting C and D.

Task-Specific Deep Eutectic Solvent for Efficient Dissolution and Further Accelerating Alkaline Hydrolysis of Polyesters Into Their Monomers.

Polyester plastics have brought great convenience to modern society. However, the continuous accumulation of their production increasingly threatens human health. Polyethylene terephthalate (PET) is one of the largest type of polyester plastics and its recycling is a major challenge. In this work, deep eutectic solvent (DES) composed of thenyl alcohol and choline chloride (ChCl) was designed for efficient dissolution of PET at 165 °C for 20 min, and further accelerating complete alkaline hydrolysis of PET into its monomer terephthalic acid (TPA) and ethylene glycol (EG) with a high TPA monomer yield (98.2 %) in 25 min at 100 °C. Moreover, the designed DES is also efficient for dissolution and alkaline hydrolysis of other polyester plastics, including poly(trimethylene terephthalate) (PTT) and poly(ethylene furanoate) (PEF) into their monomers. This work provides a feasible and sustainable solution for the recycling of polyester wastes.

Co single atoms/nanoparticles over carbon nanotubes for synergistic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid

The preparation of high-value 2,5-furandicarboxylic acid (FDCA) from biomass-based platform compound 5-hydroxymethylfurfural (HMF) is an important synthetic reaction, as the resulting FDCA holds promise to replace terephthalic acid to produce environmentally friendly polyester materials. However, due to the complex tandem nature of the oxidation of HMF to FDCA, which involves several stable intermediates, efficient conversion of HMF and achieving a high FDCA yield remain challenging. Herein, a catalyst of Co SAs/NPs@N-CNTs comprising Co single atoms (Co SAs) alongside Co nanoparticles (Co NPs) supported on carbon nanotubes (CNTs) was synthesized. Co SAs/NPs@N-CNTs exhibited outstanding catalytic activity for the selective oxidation of HMF to FDCA, achieving 100% HMF conversion and 94.2% FDCA yield. This remarkable performance was attributed to the synergistic effect between Co SAs and Co NPs. Poisoning and acid treatment experiments indicated that Co SAs served as the active sites, while Co NPs did not directly act as active sites. Instead, Co NPs merely assisted the Co SAs on the sidelines, facilitating the efficient conversion of HMF into various intermediates and promoting the further conversion of these intermediates into FDCA, thereby achieving high FDCA productivity. This strategy offers new insights for designing efficient catalysts for complex tandem reactions.

Z-Scheme Enabled 1D/2D Nanocomposite of ZnO Nanorods and Functionalized g-C3 N4 Nanosheets for Sustainable Degradation of Terephthalic Acid.

The urgent need to mitigate water pollution and achieve Sustainable Development Goal 14 (SDG 14)-Life below water, necessitates developing efficient and eco-friendly wastewater treatment technologies. This research addresses this challenge by photocatalytic degradation of terephthalic acid, a precursor for PET bottles using environment-friendly and biocompatible photocatalysts. The 1D/2D nanocomposite comprising zinc oxide (ZnO) nanorods and functionalized graphitic carbon nitride (Zn-TG) nanosheets were synthesized and thoroughly characterized. The nanocomposite effectively mitigated the individual drawbacks of Zn-TG agglomeration and the wide band gap of ZnO as confirmed through zeta potential and Tauc's plot studies, respectively. The synthesized nanocomposite achieved ~100 % degradation within 60 minutes, exhibiting superior kinetics (~2.5 times) compared to pristine samples. The enhanced degradation efficiency was elucidated by efficient charge carrier transfer (~5 times faster) and separation (~2 times improved) as confirmed through electrochemical impedance spectroscopy and time-resolved photoluminescence studies. The proposed Z-scheme pathway provides mechanistic insights. This proposed mechanism is supported by extensive electron paramagnetic resonance (EPR) and scavenger studies. The liquid chromatography-mass spectrometry (LC-MS) analysis confirms the formation of less toxic byproducts for ensuring that the wastewater treatment process is efficient and environmentally friendly. This research helps in developing a highly effective and sustainable wastewater treatment technology.

Tuning the performance of a TphR-based terephthalate biosensor with a design of experiments approach

Transcription factor-based biosensors are genetic tools that aim to predictability link the presence of a specific input stimuli to a tailored gene expression output. The performance characteristics of a biosensor fundamentally determines its potential applications. However, current methods to engineer and optimise tailored biosensor responses are highly nonintuitive, and struggle to investigate multidimensional sequence/design space efficiently. In this study we employ a design of experiments (DoE) approach to build a framework for efficiently engineering activator-based biosensors with tailored performances, and we apply the framework for the development of biosensors for the polyethylene terephthalate (PET) plastic degradation monomer terephthalate (TPA). We simultaneously engineer the core promoter and operator regions of the responsive promoter, and by employing a dual refactoring approach, we were able to explore an enhanced biosensor design space and assign their causative performance effects. The approach employed here serves as a foundational framework for engineering transcriptional biosensors and enabled development of tailored biosensors with enhanced dynamic range and diverse signal output, sensitivity, and steepness. We further demonstrate its applicability on the development of tailored biosensors for primary screening of PET hydrolases and enzyme condition screening, demonstrating the potential of statistical modelling in optimizing biosensors for tailored industrial and environmental applications.

Simple enzymatic depolymerization process based on rapid ball milling pretreatment for high-crystalline polyethylene terephthalate fibers

The high crystallinity (30 %–50 %) of discarded polyester textile waste limits the industrialization of its clean enzymatic depolymerization. In this study, a simple process based on ball milling pretreatment was developed to achieve effective enzymatic hydrolysis of high-crystalline polyester fiber. Ball milling was selected for its short, mild, and chemical-free process, which achieved a remarkable 23.8-fold (60.9 %) increase in terephthalic acid (TPA) yield from waste polyethylene terephthalate (PET) degradation, along with high TPA purity in the released soluble compounds. Just 30 min of ball milling at room temperature induced polyester amorphization, resulting in polyester with 12 % lower crystallinity compared with untreated polyester (51 %), while simultaneously increasing the surface roughness of polyester, thereby enhancing the efficiency of enzymatic hydrolysis. The simple process for effective enzymatic-depolymerization of waste polyester fiber developed in this study has potential industrial applications

Modulating structure of Ce-UiO-66 by introducing fluorinated terephthalic acid for enhanced removal efficiency of antibiotics: Insights into degradation kinetics and pathways

In this work, the 2-fluoroterephthalic acid with asymmetric structure and high electronegative F species was introduced in the assembly of Ce-UiO-66 catalysts to increase the defect density and enlarge pore structure for enhancement in removal efficiency of sulfamethoxazole. Owing to the strong coordination ability from high electronegative F species of 2-fluoroterephthalic acid with Ce-oxo nodes, the designed CUF exhibited improved interfacial properties (accelerated electron transfer rate, available active sites and enhanced interaction with PMS), which was favorable for the exploration and accessibility of active sites with sulfamethoxazole and PMS to decrease the adsorption barrier and accelerate PMS activation. As a result, the CUF catalysts exhibited higher adsorption capacity (173.4 mg/g) than that of CUH (117.8 mg/g), the enhanced degradation efficiency of sulfamethoxazole with a rate constant higher than 2.3 times CUH, good elimination (>95 %) of methylene blue, tetracycline and ibuprofen. In addition, the CUF/PMS system possessed satisfactory stability in wide solution pH, recycling and real water and good potential application in continuous wastewater treatment based on the designed dynamic catalytic reactor. This work provided deep insight into the design of catalysts with high adsorption performance and degradation efficiency based on the structure–activity relationship.

High-performance copper terephthalic acid metal-organic framework/gum Arabic/carrageenan composite beads for efficient lead(II) removal from aqueous solutions

Lead (Pb(II)) contamination poses a significant threat to human health and the environment. This study investigates a new approach for Pb(II) removal from polluted water using copper terephthalic acid metal-organic framework/gum Arabic/potassium carrageenan (MGC) composite beads. We synthesized copper terephthalic acid MOF, potassium carrageenan beads, and MGC composite beads to evaluate their adsorption potential. Characterization of the synthesized adsorbents was performed using TGA, nitrogen adsorption/desorption, ATR-FTIR, zeta potential, SEM, and TEM analyses, revealing that MOF > MGC > KG in thermal stability. The MGC composite exhibited a high specific surface area (398.03 m2/g) with mesopores and diverse functional groups, alongside a pH of zero point charge (pHpzc) of 6.8 and a small particle size (20 nm). The maximum Langmuir adsorption capacity for Pb(II) removal by MGC reached 374.7 mg/g under optimized conditions (20 °C, pH 5, 60 min shaking time, 3.0 g/L adsorbent dosage). The adsorption data fit well with the Pseudo-First-Order kinetic model and Langmuir and Dubinin-Radushkevich isotherm models. The adsorption process was physical, favorable, and endothermic. EDTA was used as a desorption agent, showing that the composite beads retained 97 % efficiency after ten cycles, highlighting MGC's potential as a sustainable strategy for Pb(II) remediation.

Sustainable waste-treating-waste strategy: Catalytic recycling of polyethylene terephthalate over reconstructed waste catalysts

Polyethylene terephthalate (PET) is the most widely used polyester plastic, but difficulties associated with PET recycling have led to significant environmental issues. The recycling of PET waste into building monomers and valuable chemicals has attracted increasing attention. Herein, we propose a sustainable circular strategy for efficiently hydrogenolytic depolymerizing the waste PET by using reconstructed spent catalysts from the heavy oil slurry-phase hydrocracking. Two types of molybdenum sulphide/activated petroleum-based carbon compounds, a-MoSx/APC and MoS2/APC, were constructed using waste refining catalyst through the activation and annealing methods, which were used as catalysts for the hydrogenolytic depolymerisation of waste PET. Experimental results revealed that the different active components in the two reconstructed catalysts, molybdenum sulphide clusters, and few-layered molybdenum disulfide, show different activity and selectivity for the catalytic depolymerisation of PET. After the β-scission process of PET, the formed intermediate vinyl-terminated carboxylate units are converted to monoethyl terephthalate (MET) through a CC insertion pathway catalyzed by MoV, while to terephthalic acid (TPA) through a hydrogenolysis pathway catalyzed by MoIV. Therefore, MoS2/APC converts PET to TPA with a yield of 83 % within 24 hours at 270 °C under 1 atmosphere of H2 and solvent-free conditions, without generating any MET products. Moreover, this process is effective for both commercial and waste PET, and the catalyst could be reused for at least ten runs with stable activity. The sustainable waste-treating-waste strategy highlights a potential approach to the circular economy.

Effect of solvent in the solvothermal synthesis of nickel(II)-terephthalate complex

This research aims to replace the use of dimethylformamide (DMF) with a greener solvent in the solvothermal synthesis of nickel(II)-terephthalate complex. Effect of solvent on the crystallinity degree, thermal stability, and band gap energy of the synthesized complex are also studied. The synthesis was carried out using solvothermal method at 150 0C for 10 hours with a Ni(II) : terephthalate acid mol ratio of 1:1 in several H2O:DMF solvent compositions (1:0; 1:1; and 0:1). The precipitated products underwent characterization using ATR-IR, P-XRD, SEM, TGA, Surface Area Analyzer, and UV-DRS. Findings revealed the successful formation of the Ni(II)-terephthalate complex using three different solvent compositions (H2O/DMF = 1:0, 1:1, and 0:1). This suggests that the complex can be synthesized using more environmentally friendly solvents, potentially reducing or substituting the use of DMF solvent. However, the solvent affects the characteristics of the synthesized complex, in which green block microcrystalline solid was obtained when using water as the solvent, meanwhile green aggregates with lower crystallinity degree was precipitated out when using DMF or H2O-DMF. The Ni(II)-terephthalate complexes obtained from the H2O and H2O-DMF solvents are different to that of from the DMF solvent, but they both has identical powder diffraction pattern with previously reported compound of [Ni3(OH)2(C8H4O4)2(H2O)4].2H2O. Furthermore, the use of water as the solvent increase the crystallinity degree and thermal stability of the complex but the band gap energy of the synthesized Ni(II)-terephthalate complex compared to that of obtained from the DMF solvents.

Preparation of NiCo hydroxide by chloride corrosion for electrocatalytic upcycling of polyethylene terephthalate plastic waste

Upcycling plastic waste into value-added chemicals is an innovative strategy that addresses environmental concerns and creates economic value. As one of the polyesters that is widely used, polyethylene terephthalate (PET) plastic waste is employed as the model substrate. Here we report a chloride corrosion method to synthesize bimetallic hydroxide catalysts on nickel foam. By using a nickel–cobalt hydroxide catalyst (NiCo-OH/NF), we demonstrate an electrocatalytic oxidation strategy to transform real-world polyethylene terephthalate (PET) water bottle into potassium formate and terephthalic acid (TPA) with high Faraday efficiency of 92.1 % at 1.40 V vs. RHE. The in situ spectroscopy and theoretical calculations provide insights into the catalytic mechanism especially active sites, pivotal intermediates, and favorable pathways. This work highlights the significant potential of electrochemical conversion as a means of achieving PET upcycling.

Fe-MOF-based catalysts for oxygen evolution reaction: Microenvironment regulated by organic ligands, metals and carbonization synergistically

In this work, novel catalysts towards oxygen evolution reaction were designed based on Fe-MOF materials. The issues concerning the microenvironment of active sites, such as organic ligands and metal sites, were investigated in detail. Fe-BDC derived from terephthalic acid (H2BDC) displayed better performance compared with Fe-FDCA generated by 2,5-furanedicarboxylic acid (FDCA) due to the difference in electron cloud density of Fe active sites. The additional introduction of metal sites improved the catalytic activity of Co-Fe-BDC and Ni-Fe-BDC with faster reaction kinetics, but its relatively few active sites resulted in oxygen evolution reaction (OER) performance similar to that of the initial Fe-BDC. The pyrolysis of Co/Ni-Fe-BDC afforded carbon-based catalyst Co-Fe-C, possessing an extremely low overpotential (208 mV) at 10 mA/cm2 and high electrocatalytic stability after 36 h of continuous operation, relative to Fe-BDC (249 mV). The high catalytic performance was attributed to the compact and efficient microenvironment of active sites. This study provided a new strategy for the development of efficient and durable electrocatalysts for OER.

Potassium Carbonate as a Low-Cost and Highly Active Solid Base Catalyst for Low-Temperature Methanolysis of Polycarbonate.

As the demand for polycarbonate (PC) plastic increases over the years, the development of a chemical recycling system to produce virgin-like-quality monomers is indispensable not only to attain completely sustainable cycles but also to contribute to the decrease in global plastic pollution. Herein, potassium carbonate (K2CO3) was used as a low-cost, readily available, and highly active solid base catalyst for low-temperature PC methanolysis in the presence of THF as a solvent, producing highly pure and crystalline bisphenol A (BPA) and with a catalytic performance higher than group IIA metal oxides (MgO, CaO, and SrO) and some group IA metal carbonates (NaHCO3, KHCO3, and Na2CO3). THF was the best solvent in aiding the reaction owing to it having a similar polar parameter (δp) to that of PC according to Hansen solubility parameters. By the reaction over the catalyst, 100% PC conversion, 97% BPA yield, and 86% dimethyl carbonate yield were achieved within just 20 min at 60 °C. The catalyst possessed an apparent activation energy (Ea) of 52.3 kJ mol-1, which is the lowest value so far for heterogeneous catalysts, while the mechanistic study revealed that the reaction proceeded via the methoxide pathway. The reusability test demonstrated that the catalyst was reusable at least four times. Furthermore, this catalytic system was successfully applied to actual post-consumerPC wastes and polyesters, including polyethylene terephthalate (PET) and polylactic acid (PLA).

Ligand modulated charge transfers in Z-scheme configured Ni-MOF/g-C3N4 nanocomposites for photocatalytic remediation of dye-polluted water

The development of photocatalysts must be meticulous, especially when they are designed to degrade hazardous dyes that cause mutagenesis and carcinogenesis. In this meticulous approach, Ni-based metal–organic frameworks with different ligands, including terephthalic acid (NTP), 2-aminoterephthalic acid (NATP), and their composite with g-C3N4 (NTP/GCN, and NATP/GCN) have been synthesized using hydrothermal method. Structural analysis by XRD and ATR-IR revealed synergistic properties due to robust chemical interactions between the NATP-MOFs and GCN systems. A flower-like morphology was observed for both NTP and NATP, while their composites showed mixed-particulate structures mimicking the morphology of GCN. Optical analyses indicated visible-light driven properties with modulated recombination resistance in the system. Among the synthesized bare and composite systems, NATP/GCN exhibited the highest photocatalytic degradation efficiency for the cationic rhodamine B dye (~ 93% in 120 min), while it was relatively less efficient for the anionic Congo red dye, (~ 64% in 120 min). The insights gained from the fundamental characterizations including Mott–Schottky, scavenger, and electrochemical impedance analysis revealed that the amino-groups in NATP/GCN composite offered the band edge potentials suitable for the effective generation of energetic radical species with the improved carrier delocalization, recombination resistance, and charge transfer properties in the composite system through Z-scheme formation. Parametric investigations by varying the concentration of catalyst, dye, and pH along with recycle studies, demonstrated the excellent stability of the developed composites for sustainable photocatalytic applications.

Reinforcing the Efficiency of Plastic Upgrading through Full-Spectrum Photothermal Effect Integration of Heat Isolator.

Photoreforming of polyethylene terephthalate (PET) to H2 is practically attractive strategy for upgrading waste plastics. The major challenge is to utilize the infrared energy in the solar spectrum to improve the efficiency for photoreforming of PET to H2. Herein, through the ingenious integration of tungsten phosphide nanoparticles and tungsten single atoms (WP/W SAs) with carbon nitride (g-C3N4), the constructed hybrid inherits both the desirable properties and structural merits of the respective building blocks. Specifically, the photothermal effect of WP/W SAs couples with the "heat isolator" role of g-C3N4 due to its low thermal conductivity, thereby forming localized high-temperature regions, reducing the activation energy and improving the kinetics in the photoreforming of PET to H2. Additionally, the green pretreatment of PET using alkali-free hydrothermal strategy is reported, achieving direct separation of the ethylene glycol and terephthalic acid. This work not only provides an alkali-free hydrothermal pretreatment for PET, but also integrates the photothermal effect with the thermal insulation and opens a new avenue for harnessing solar energy into to convert plastics into H2.

Application of Ni‐Based MOFs Catalyst in Oxidative Coupling Reaction of Benzylamine

AbstractNanoparticles made of porous coordination polymers, known as metal‐organic frameworks (MOFs), are becoming increasingly popular in nanomaterials research, especially in catalytic applications. With their intricate architectures, MOFs make it possible to incorporate metal nodes, encapsulate substrates, and use functional linkers, all of which contribute to synergistic engineering. A Ni‐based metal‐organic framework sample was prepared by the solvothermal method with NiCl2.6H2O as a precursor of Ni metal and terephthalic (H2BDC) acid as a linker. The as‐synthesized NiBDC was verified by X‐ray diffraction (XRD), Fourier‐transform infrared spectroscopy (FT‐IR), scanning electron microscopy (SEM), scanning electron microscopy with energy dispersive X‐ray spectroscopy (SEM‐EDX), transmission electron microscopy (TEM), and N2 adsorption/desorption isotherms. Based on these findings, we applied the as‐synthesized NiBDC to the oxidative coupling reaction of benzylamine. The results revealed that with NiBDC as a heterogeneous catalyst, the oxidative coupling reaction of benzylamine achieved a performance of 92%. Furthermore, the catalyst maintains good stability after four catalytic cycles, with an efficiency of approximately 82%.

Development of the esterase PestE for amide bond synthesis under aqueous conditions: Enzyme cascades for converting waste PET into tamibarotene.

A growing number of hydrolase enzymes show promiscuous acyltransferase activity, even under aqueous conditions. Here we report, for the first time, the ability of Pyrobaculum calidifontis VA1 esterase (PestE) to catalyse the formation of a wide range of amides in buffer, where the acyl donor forms a significant structural component in the amide product. The reactions occur under mild conditions and can achieve conversions up to 97% in 6 h for formation of N‐benzylfuranamide as the model reaction. We demonstrate PestE’s potential in enzyme cascades to make amides from waste PET plastic and the conversion of the terephthalic acid product to tamibarotene, a drug with activity against acute leukemia. Rational mutagenesis led to identification of PestE variants F33L_F289A and F33L. F33L_F289A increased conversion of N‐benzylfuranamide by 1.2‐fold, and F33L gave a 4‐fold increase in conversion to tamibarotene.

Development of the esterase PestE for amide bond synthesis under aqueous conditions: Enzyme cascades for converting waste PET into tamibarotene.

A growing number of hydrolase enzymes show promiscuous acyltransferase activity, even under aqueous conditions. Here we report, for the first time, the ability of Pyrobaculum calidifontis VA1 esterase (PestE) to catalyse the formation of a wide range of amides in buffer, where the acyl donor forms a significant structural component in the amide product. The reactions occur under mild conditions and can achieve conversions up to 97% in 6 h for formation of N-benzylfuranamide as the model reaction. We demonstrate PestE's potential in enzyme cascades to make amides from waste PET plastic and the conversion of the terephthalic acid product to tamibarotene, a drug with activity against acute leukemia. Rational mutagenesis led to identification of PestE variants F33L_F289A and F33L. F33L_F289A increased conversion of N-benzylfuranamide by 1.2-fold, and F33L gave a 4-fold increase in conversion to tamibarotene.