ABSTRACT
This study addresses the challenge of designing simple and environmentally friendly methods for the preparation of effective electromagnetic wave (EMW) absorbing materials with tailored microstructures and multi-component regulation. N, O doped walnut-like porous carbon composite microspheres loaded with FeCo nanoparticles (WPCM/Fe-Co) are synthesized through high-temperature carbonization combined with soap-free emulsion polymerization and hydrothermal methods, avoiding the use of toxic solvents and complex conditions. The incorporation of magnetic components enhances magnetic loss, complementing dielectric loss to optimize EMW attenuation. The unique walnut-like morphology further improves impedance matching. The proportions of Fe and Co components can be adjusted to regulate the material's reflection loss, thickness, and bandwidth, allowing for fine-tuning of absorption performance. At a low filling ratio (16.7%), the optimal WPCM/Fe-Co composites exhibit a minimum reflection loss (RLmin) of -48.34 dB (10.33 GHz, 3.0 mm) and an overall effective absorbing bandwidth (EAB) covering the entire C bands, X bands, and Ku bands. This work introduces a novel approach to composition regulation and presents a green synthesis method for magnetic carbon composite absorbers with high-performance EMW absorption at low loading.
ABSTRACT
Conventional adhesives experience reduced adhesion when exposed to aqueous environments. The development of underwater adhesives capable of forming strong and durable bonds across various wet substrates is crucial in biomedical and engineering domains. Nonetheless, limited emphasis placed on retaining high adhesion strengths in different saline environments, addressing challenges such as elevated osmotic pressure and spontaneous dimensional alterations. Herein, a series of ionogel-based underwater adhesives are developed using a copolymerization approach that incorporates "dynamic complementary cross-linking" networks. Synergistic engineering of building blocks, cross-linking networks, pendant groups and counterions within ionogels ensures their adhesion and cohesion in brine spanning a wide salinity range. A high adhesion strength of ≈3.6 MPa is attained in freshwater. Gratifyingly, steady adhesion strengths exceeding 3.3 MPa are retained in hypersaline solutions with salinity ranging from 50 to 200 g kg-1, delivering one of the best-performing underwater adhesives suitable for diverse saline solutions. A combination of outstanding durability, reliability, deformation resistance, salt tolerance, and self-healing properties showcases the "self-contained" underwater adhesion. This study shines light on the facile fabrication of catechol-free ionogel-based adhesives, not merely boosting adhesion strengths in freshwater, but also broadening their applicability across various saline environments.
ABSTRACT
Solid-state contact ion-selective electrodes (SC-ISEs) are an efficacious means of monitoring heavy metal contamination. Instability of the electrode potential is a key factor limiting their development, with biofouling in real water samples posing a significant challenge to maintaining stability. Therefore, addressing biofouling is crucial for optimizing solid-state ion-selective electrodes. In this work, high stability and antibiofouling capability in a solid-state contact lead ion-selective electrode (SC-Pb2+-ISE) based on polyaniline (PANI) was achieved through cathodic polarization. Specifically, PANI played a dual role in the ion-selective membrane (ISM) as an ion-to-electron transducer and antifouling agent. Given the excellent electrochemical performance of PANI, the prepared electrode (GC/PANI-Pb2+-ISM) demonstrated a remarkable antibiofouling efficiency of 98.2% under a cathodic polarization of -0.2 V. Furthermore, a standard deviation of standard potential (Eθ) as low as ± 0.5 mV was realized successfully. The excellent chrono-potentiometric stability of 17.0 ± 2.9 µV/s was also demonstrated. The electrode maintained a Nernstian response slope of 30.7 ± 0.2 (R2 = 0.998) after applying a cathode potential (-0.2 V) for 30 min. The developed GC/PANI-Pb2+-ISM electrode is suitable for practical applications in real environmental water sample monitoring.
ABSTRACT
Calcium overload and ROS overproduction, two major triggers of acute kidney injury (AKI), are self-amplifying and mutually reinforcing, forming a complicated cascading feedback loop that induces kidney cell "suicide" and ultimately renal failure. There are currently no clinically effective drugs for the treatment of AKI, excluding adjuvant therapy. In this study, a porous silicon-based nanocarrier rich in disulfide bond skeleton (<50 nm) is developed that enables efficient co-loading of the hydrophilic drug borane amino complex and the hydrophobic drug BAPTA-AM, with its outer layer sealed by the renal tubule-targeting peptide PEG-LTH. Once targeted to the kidney injured site, the nanocarrier structure collapses in the high glutathione environment of the early stage of AKI, releasing the drugs. Under the action of the slightly acidic inflammatory environment and intracellular esterase, the released drugs produce hydrogen and BAPTA, which can rapidly eliminate the excess ROS and overloaded Ca2+ , blocking endoplasmic reticulum/mitochondrial apoptosis pathway (ATF4-CHOP-Bax axis, Casp-12-Casp-3 axis, Cyt-C-Casp-3 axis) and inflammatory pathway (TNF-α-NF-κB axis) from the source, thus rescuing the renal cells in the "critical survival" state and further restoring the kidney function. Overall, this nanoparticle shows substantial clinical promise as a potential therapeutic strategy for I/R injury-related diseases.
Subject(s)
Acute Kidney Injury , Calcium , Humans , Calcium/metabolism , Reactive Oxygen Species/metabolism , Feedback , Apoptosis , Acute Kidney Injury/drug therapy , Acute Kidney Injury/metabolism , Kidney/metabolismABSTRACT
Two-Dimensional (2D) materials have attracted immense attention in recent years. These materials have found their applications in various fields, such as catalysis, adsorption, energy storage, and sensing, as they exhibit excellent physical, chemical, electronic, photonic, and biological properties. Recently, researchers have focused on constructing porous structures on 2D materials. Various strategies, such as chemical etching and template-based methods, for the development of surface pores are reported, and the porous 2D materials fabricated over the years are used to develop supercapacitors and energy storage devices. Moreover, the lattice structure of the 2D materials can be modulated during the construction of porous structures to develop 2D materials that can be used in various fields such as lattice defects in 2D nanomaterials for enhancing biomedical performances. This review focuses on the recently developed chemical etching, solvent thermal synthesis, microwave combustion, and template methods that are used to fabricate porous 2D materials. The application prospects of the porous 2D materials are summarized. Finally, the key scientific challenges associated with developing porous 2D materials are presented to provide a platform for developing porous 2D materials.
ABSTRACT
Solar-powered interfacial heating has emerged as a sustainable technology for hybrid applications with minimal carbon footprints. Aerogels, hydrogels, and sponges/foams are the main building blocks for state-of-the-art photothermal materials. However, these conventional three-dimensional (3D) structures and related fabrication technologies intrinsically fail to maximize important performance-enhancing strategies and this technology still faces several performance roadblocks. Herein, monolithic, self-standing, and durable aerogel matrices are developed based on composite photothermal inks and ink-extrusion 3D printing, delivering all-in-one interfacial steam generators (SGs). Rapid prototyping of multiscale hierarchical structures synergistically reduce the energy demand for evaporation, expand actual evaporation areas, generate massive environmental energy input, and improve mass flows. Under 1 sun, high water evaporation rates of 3.74 kg m-2 h-1 in calm air and 25.3 kg m-2 h-1 at a gentle breeze of 2 m s-1 are achieved, ranking among the best-performing solar-powered interfacial SGs. 3D-printed microchannels and hydrophobic modification deliver an icephobic surface of the aerogels, leading to self-propelled and rapid removal of ice droplets. This work shines light on rational fabrication of hierarchical photothermal materials, not merely breaking through the constraints of solar-powered interfacial evaporation and clean water production, but also discovering new functions for photothermal interfacial deicing.
ABSTRACT
Liquid-crystal small molecule donor (LC-SMD) is a new type organic semiconductor, which is attractive not only for the easy synthesis and purification, well-defined chemical structures, etc., but also for the LC state that makes the crystallinity and aggregation state of molecules adjustable. Here, one new LC-SMD (a-BTR-H4) is synthesized with 1D alkoxyl and 2D thiophene-alkylthiol side-chained benzo[1,2-b:4,5-b']dithiophene core, trithiophene π-bridge, and 3-(2-ethylhexyl) rhodanine end group. a-BTR-H4 shows low LC transition temperature, 117 °C, however, counterpart material (a-BTR-H5) with the same main structure but 3-ethyl rhodanine terminal group does not show LC properties. Although a-BTR-H4/H5 show similar Ultraviolet-visible absorption spectrum and energy levels, a-BTR-H4 affords relatively high photovoltaic performances due to favorable blend morphology produced by the consistent annealing temperature of Y6-based accepters and liquid crystal temperature of donors. Preliminary results indicate that a-BTR-H4 gains a power conversion efficiency (PCE) of 11.36% for Y6-based devices, which is ascribed to better light harvest as well as balanced carrier generation and transport, while a-BTR-H5 obtains 7.57% PCE. Therefore, some materials with unique nematic LC phase have great application potential in organic electronics, and further work to utilize a-BTR-H4 for high-performance device is underway.
ABSTRACT
Marine resources in unique marine environments provide abundant, cost-effective natural biomaterials with distinct structures, compositions, and biological activities compared to terrestrial species. These marine-derived raw materials, including polysaccharides, natural protein components, fatty acids, and marine minerals, etc., have shown great potential in preparing, stabilizing, or modifying multifunctional nano-/micro-systems and are widely applied in drug delivery, theragnostic, tissue engineering, etc. This review provides a comprehensive summary of the most current marine biomaterial-based nano-/micro-systems developed over the past three years, primarily focusing on therapeutic delivery studies and highlighting their potential to cure a variety of diseases. Specifically, we first provided a detailed introduction to the physicochemical characteristics and biological activities of natural marine biocomponents in their raw state. Furthermore, the assembly processes, potential functionalities of each building block, and a thorough evaluation of the pharmacokinetics and pharmacodynamics of advanced marine biomaterial-based systems and their effects on molecular pathophysiological processes were fully elucidated. Finally, a list of unresolved issues and pivotal challenges of marine-derived biomaterials applications, such as standardized distinction of raw materials, long-term biosafety in vivo, the feasibility of scale-up, etc., was presented. This review is expected to serve as a roadmap for fundamental research and facilitate the rational design of marine biomaterials for diverse emerging applications.
Subject(s)
Biocompatible Materials , Polysaccharides , Biocompatible Materials/pharmacology , Biocompatible Materials/chemistry , Polysaccharides/chemistry , Tissue Engineering , Drug Delivery SystemsABSTRACT
Long-term and green marine antifouling coatings are an important means to prolong the service life of ships and other marine instruments and equipment. To accomplish this, we prepared three new green and high-efficiency antifouling coatings containing phthalimide derivatives inspired by capsaicin (PDIC-AC) by using a collaborative strategy that incorporates self-polishing, fouling repelling, and antifouling properties. Static simulation tests confirmed that the zinc acrylate resin of the PDIC-AC has excellent self-polishing properties due to changes in the roughness, surface free energy, and mass loss. Antifouling tests demonstrated that both PDIC and PDIC-AC possess efficient antibacterial and anti-algal effects. Moreover, marine field tests showed that the PDIC-AC are highly antifouling for at least 9 months, and their antifouling effect is similar to that of an antifouling coating with chlorothalonil (CT-AC). The collaborative strategy in this study can be used to research and develop long-term environmentally friendly antifouling coatings.
Subject(s)
Biofouling , Anti-Bacterial Agents , Biofouling/prevention & control , Surface PropertiesABSTRACT
The evidence from many studies shows that antifoulants (Cu2O) and organic antifouling agents with broad-spectrum characteristics in antifouling coatings cause varying degrees of damage to the environment. Therefore, this study prepared Cu2O-free self-polishing antifouling coatings based on amide derivatives inspired by capsaicin (ADIC-CSAC) with green and environmentally friendly characteristics. First, the structure of ADIC and the composition of ADIC-CSAC were characterized by IR, 1H NMR, 13C NMR, HRMS, and EDX. Moreover, antibacterial, anti-algal, static raft tests and changes in the mass loss, roughness, contact angle, and surface energy were used to evaluate the antifouling and self-polishing properties of ADIC-CSAC. The test results showed that ADIC and ADIC-CSAC were successfully prepared and ADIC-CSAC possessed good antifouling and self-polishing properties. ADIC-CSAC exhibited antibacterial and anti-algal rates of over 88 and 72%, respectively, and was found to have satisfactory antifouling properties over 9 months in a real marine field. Overall, the prepared ADIC-CSAC possesses good and green antifouling and self-polishing properties, which lays a foundation for research on green antifouling coatings used for environmental protection.
Subject(s)
Biofouling , Amides , Anti-Bacterial Agents/chemistry , Anti-Bacterial Agents/pharmacology , Biofouling/prevention & control , Capsaicin/pharmacologyABSTRACT
In this study, eight polyphenol derivatives were prepared to serve as green antifoulants. Polyphenol derivatives, which can hinder the growth of bacteria and algae and decrease the adhesion of some marine organisms, showed good AF activity; in particular, the activities of these derivatives were much higher than those of the corresponding polyphenols. The antibacterial rates of the products (20 µg ml-1) exceeded 88%. Moreover, the anti-algal rates of compounds a3, b1, b2, b3 and b4 (15 µg ml-1) were over 57% at 240 h, but these compounds showed low toxicity, and the 120 h EC50 values were > 6.60 µg ml-1. In addition, there were fewer marine microorganisms on the test panel than on the control. The above results show that some polyphenol derivatives possess relatively high antibacterial, anti-algal, and AF activity; more notably, the addition of chlorine atoms and amide groups can further increase the activity of these derivatives.
Subject(s)
Biofouling , Polyphenols , Anti-Bacterial Agents/pharmacology , Aquatic Organisms , Biofilms , Biofouling/prevention & control , Polyphenols/pharmacologyABSTRACT
Peptide/protein therapeutics have been significantly applied in the clinical treatment of various diseases such as cancer, diabetes, etc. owing to their high biocompatibility, specificity, and therapeutic efficacy. However, due to their immunogenicity, instability stemming from its complex tertiary and quaternary structure, vulnerability to enzyme degradation, and rapid renal clearance, the clinical application of protein/peptide therapeutics is significantly confined. Though nanotechnology has been demonstrated to prevent enzyme degradation of the protein therapeutics and thus enhance the half-life, issues such as initial burst release and uncontrollable release kinetics are still unsolved. Moreover, the traditional administration method results in poor patient compliance, limiting the clinical application of protein/peptide therapeutics. Exploiting the sustained-release formulations for more controllable delivery of protein/peptide therapeutics to decrease the frequency of injection and enhance patient compliance is thus greatly meaningful. In this review, we comprehensively summarize the substantial advancements of protein/peptide sustained-release systems in the past decades. In addition, the advantages and disadvantages of all these sustained-release systems in clinical application together with their future challenges are also discussed in this review.
Subject(s)
Drug Delivery Systems , Peptides , Delayed-Action Preparations , Half-Life , Humans , ProteinsABSTRACT
Many gallate esters have been applied as food additives due to their good biological properties. Herein, nine novel gallate ester derivatives were synthesized by a Friedel-Crafts alkylation reaction and characterized by melting point (m.p.), infrared (IR) spectroscopy, nuclear magnetic resonance (1 H- and 13 C-NMR) spectra, and high-resolution mass spectrometry (HR-ESI-MS). Their antioxidant and antibacterial activities were measured using a series of classical assays. Studies found that the products showed favorable antioxidant and antibacterial activities. Their 1,1-diphenyl-2-picrylhydrazyl free radical (DPPHâ ) scavenging effect IC50 values were less than 5.00â µg mL-1 and their reducing power was not less than that of vitamin C (Vc). Furthermore, the antibacterial results showed that the minimum inhibitory concentration (MIC) values of the products were not greater than 8.00â µg mL-1 , and their antibacterial rates were over 95 % at 300â µg mL-1 . The above data add valuable and novel information that gallate ester derivatives can be considered potential food additives to address food safety issues because of their high biological activity and health benefits.
Subject(s)
Anti-Bacterial Agents/pharmacology , Antioxidants/pharmacology , Escherichia coli/drug effects , Esters/pharmacology , Gallic Acid/pharmacology , Staphylococcus aureus/drug effects , Anti-Bacterial Agents/chemical synthesis , Anti-Bacterial Agents/chemistry , Antioxidants/chemical synthesis , Antioxidants/chemistry , Biphenyl Compounds/antagonists & inhibitors , Dose-Response Relationship, Drug , Esters/chemical synthesis , Esters/chemistry , Gallic Acid/chemical synthesis , Gallic Acid/chemistry , Microbial Sensitivity Tests , Molecular Structure , Picrates/antagonists & inhibitors , Structure-Activity RelationshipABSTRACT
Solid contact-based ion-selective electrodes (SC-ISEs) based on silver nanoparticles/polyaniline (Ag@PANI) as the solid contact (SC) were successfully prepared. The Ag@PANI SC showed high capacitance and excellent electron transport performance. Owing to the synergetic effects of the Ag nanoparticles and PANI, a GC/Ag@PANI-II/Pb2+-ISE (where II refers to a Ag content of 0.01 wt% in the SC layer) showed a low Pb2+ detection limit (6.31 × 10-10 M) with a slope of 29.1 ± 0.3 mV/dec, a fast response (< 5 s), and high stability. GC/Ag@PANI-II/Pb2+-ISE exhibited a Nernstian response for Pb2+ ions over a wide concentration range (10-3 to 10-9 M). After a 3-week operation, GC/Ag@PANI-II/Pb2+-ISE responded linearly to Pb2+ over the range of 10-7-10-3 M, demonstrating good long-term potential stability. Furthermore, the electrode showed excellent reproducibility and repeatability of the potential values and was successfully applied to detect the Pb2+ concentration in real samples with a recovery of 97 - 109%. Results suggest that Ag@PANI composites offer good transducer performance in trace ion detection sensors.
ABSTRACT
Indole derivatives derived from the secondary metabolites of marine organisms possess the excellent antifouling property to inhibit the biofouling. These compounds and their analogues are simple in structure and have been proven to have low toxicity and bioaccumulation. Therefore, the active indole antifoulants are expected to replace the potentially toxic antifoulants which are widely used in current antifouling coatings. Seven indole derivatives were synthesized via the Friedel-Crafts alkylation reaction and were characterized by IR spectra, 1H NMR, 13C NMR and elemental analysis. Inhibition experiments against marine algae and bacteria were conducted, and the partial inhibition rates of algae and bacteria were more than 90%. This outcome indicates that indole derivatives possess excellent properties suitable for use as targeting anti-fouling compound for algae and bacteria. Non-invasive Micro-test Technology (NMT) reveals that the Ca2+ efflux of Platymonas subcordiformis dramatically increased in the presence of indole derivatives, which is inferred to be the molecular mechanism for inhibiting the growth of marine algae. The antifouling coatings containing indole derivatives were prepared and subjected to an antifouling test in a marine environment, and the results show that N-(1-H-5-bromo-indole-3-ylmethyl) benzamide and N-(1-H-2-phenyl-indole-3-ylmethyl) benzamide possess better antifouling performance compared to copper pyrithione (CuPT). According to these results, indole derivatives in this study might become novel and promising antifoulants.
Subject(s)
Biofouling/prevention & control , Disinfectants/toxicity , Indoles/toxicity , Aquatic Organisms , Bacteria/growth & developmentABSTRACT
The 2D asymmetric benzodithiophene (BDT) unit is used as a donor unit to construct one new polymer PBDTBDD-Th with benzo[1,2-c:4,5-c']dithiophene-4,8-dione (BDD) as acceptor building block. In comparison to the polymer PBDTsTh-BDD with a side chain containing a sulfur atom, the devices based on PBDTBDD-Th/ITIC show better performance due to the introduction of carbon atoms in the side chain, which could weaken the self-aggregations of polymer chains. As a result, the devices based on PBDTBDD-Th/ITIC blends yield power conversion efficiencies (PCEs) over 10%, much higher than those based on PBDTsTh-BDD/ITIC blends (7.09%). The exciton dissociation probabilities (P diss ) of a device based on PBDTBDD-Th/ITIC blends is 95.3%, which suggests that the device achieves good exciton dissociation and charge transfer. In general, the polymer PBDTBDD-Th shows capability to increase the PCEs of polymer solar cells (PSCs) with a non-fullerene acceptor.
Subject(s)
Polymers/chemistry , Solar Energy , Thiophenes/chemistry , Molecular Structure , Polymers/chemical synthesisABSTRACT
Benzo[c][1,2,5]oxadiazole (BO) moiety is a strong electron-withdrawing unit compared to benzo[c][1,2,5]thiadiazole (BT). It is usually introduced as an acceptor to construct narrow band-gap donor-acceptor (D-A) materials. Herein, the π-extended conjugated moiety dithieno[3',2':3,4â³;2,3â³:5,6]benzo[1,2-c][1,2,5]oxadiazole (BOT) was adopted as the acceptor moiety to design D-A polymers. Considering the more extended π-conjugated molecular system of BOT compared to the BO unit, a narrower optical band-gap is expected for BOT-based IDT polymer (PIDT-BOT). Unexpectedly, the UV-vis absorption spectra of PIDT-BOT films display a great hypochromatic shift of about 60 nm compared to a BO-based analog (PIDT-BO). The optical band-gaps of the materials are broadened from 1.63 eV (PIDT-BO) to 2.00 eV (PIDT-BOT) accordingly. Although the range of external quantum efficiency (EQE) of PIDT-BOT-based polymer solar cell (PSC) devices is not as wide as for PIDT-BO-based devices, the EQE response intensities of the PIDT-BOT based device are evidently high. As a result, PSC devices based on PIDT-BOT reveal the best power conversion efficiency at 6.08%.
Subject(s)
Oxadiazoles/chemistry , Polymers/chemistry , Thiophenes/chemistry , Solar EnergyABSTRACT
Particulate matter (PM) in the Kunshan High-Tech zone is studied during a three-month campaign. PM and trace elements are measured by the online pollution monitoring, forecast-warning and source term retrieval system AS3. Hourly measured concentrations of PM10, PM2.5 and 16 trace elements in the PM2.5 section (Ca, Pb, Cu, Cl, V, Cr, Fe, Ti, Mn, Ni, Zn, Ga, As, Se, Sr, Ba) are focused. Source apportionment of trace elements by Positive Matrix Factorization modeling indicates that there are five major sources, including dust, industrial processing, traffic, combustion, and sea salt with contribution rate of 23.68%, 21.66%, 14.30%, 22.03%, and 6.89%, respectively. Prediction of plume dispersion from concrete plant and traffic emissions shows that PM10 pollution of concrete plant is three orders of magnitude more than that of the traffic. The influence range can extend to more than 3km in 1hr. Because the footprint of the industrial plumes is constantly moving according to the local meteorological conditions, the fixed monitoring sites scattered in a few hundred meters haven't captured the heaviest pollution plume at the local scale of a few km2. As a more intensive monitoring network is not operationally possible, the use of online modeling gives accurate and quantitative information of plume location, which increases the spatial pollution monitoring capacity and improves the understanding of measurement data. These results indicate that the development of the AS3 system, which combines monitoring equipment and air pollution modeling systems, is beneficial to the real-time pollution monitoring in the industrial zone.
Subject(s)
Air Pollutants/analysis , Air Pollution/statistics & numerical data , Environmental Monitoring , Particulate Matter/analysis , Industry , Trace Elements/analysisABSTRACT
The dissolution of platinum (Pt) has been one of the heart issues in developing advanced dye-sensitized solar cells (DSSCs). We present here the experimental realization of stable counter-electrode (CE) electrocatalysts by alloying Pt with transition metals for enhanced dissolution resistance to state-of-the-art iodide/triiodide (I(-)/I3(-)) redox electrolyte. Our focus is placed on the systematic studies of dissolution engineering for PtM0.05 (M=Ni, Co, Fe, Pd, Mo, Cu, Cr, and Au) alloy CE electrocatalysts along with mechanism analysis from thermodynamical aspects, yielding more negative Gibbs free energies for the dissolution reactions of transition metals. The competitive reactions between transition metals with iodide species (I3(-), I2) could protect the Pt atoms from being dissolved by redox electrolyte and therefore remain the high catalytic activity of the Pt electrode.
ABSTRACT
Dye-sensitized solar cells (DSSCs) have attracted growing interest because of their application in renewable energy technologies in developing modern low-carbon economies. However, the commercial application of DSSCs has been hindered by the high expenses of platinum (Pt) counter electrodes (CEs). Here we use Pt-free binary Co-Ni alloys synthesized by a mild hydrothermal strategy as CE materials in efficient DSSCs. As a result of the rapid charge transfer, good electrical conduction, and reasonable electrocatalysis, the power conversion efficiencies of Co-Ni-based DSSCs are higher than those of Pt-only CEs, and the fabrication expense is markedly reduced. The DSSCs based on a CoNi0.25 alloy CE displays an impressive power conversion efficiency of 8.39%, fast start-up, multiple start/stop cycling, and good stability under extended irradiation.