Carbonate Research Articles

Potential Benefits of Combining Proton or Carbon Ion Therapy with DNA Damage Repair Inhibitors.

The use of charged particle radiotherapy is currently increasing, but combination therapy with DNA repair inhibitors remains to be exploited in the clinic. The high-linear energy transfer (LET) radiation delivered by charged particles causes clustered DNA damage, which is particularly effective in destroying cancer cells. Whether the DNA damage response to this type of damage is different from that elicited in response to low-LET radiation, and if and how it can be targeted to increase treatment efficacy, is not fully understood. Although several preclinical studies have reported radiosensitizing effects when proton or carbon ion irradiation is combined with inhibitors of, e.g., PARP, ATR, ATM, or DNA-PKcs, further exploration is required to determine the most effective treatments. Here, we examine what is known about repair pathway choice in response to high- versus low-LET irradiation, and we discuss the effects of inhibitors of these pathways when combined with protons and carbon ions. Additionally, we explore the potential effects of DNA repair inhibitors on antitumor immune signaling upon proton and carbon ion irradiation. Due to the reduced effect on healthy tissue and better immune preservation, particle therapy may be particularly well suited for combination with DNA repair inhibitors.

Clinical Application and Prospect of New Radiotherapy Technology in Cancer Treatment

Objective: Carbon ion therapy, a new radiotherapy technology, has shown its remarkable efficacy and potential in cancer treatment, especially in the treatment of refractory tumors. Methods: This paper clarifies the physical basis, technological change, and clinical practice effect of carbon ion therapy, comprehensively discusses the future prospects, and evaluates the clinical application effect. Results: The technology has significantly improved the treatment effectiveness and received a positive response from patients. Conclusion: Carbon ion therapy technology has become a major innovation in the field of cancer treatment. It not only has a profound impact on many current cancer therapy methods but also indicates the application blueprint for a wider range of cancer types in the future, showing a new chapter of medical technology advancement.

Quantification of the sp3 content in Diamond-Like carbon Films: Effects of Ne plasma addition in Deep Oscillation Magnetron sputtering

Diamond-like carbon (DLC) films are a class of amorphous carbon materials with unique properties, including high hardness and wear resistance, making them attractive for aerospace and automotive applications. Recently, High Power Impulse Magnetron Sputtering (HiPIMS) has emerged as a new route for magnetron-sputtered hard DLC films. The authors have previously demonstrated that adding Ne to the plasma significantly improves the properties of DLC films deposited by Deep Oscillation Magnetron Sputtering (DOMS), a HiPIMS variant. In this study, the sp3 content evolution with DLC film thickness was measured by Electron Energy Loss Spectroscopy (EELS) and Near Edge X-ray Absorption Spectroscopy (NEXAFS). The sp3 content in the top section of the film deposited in Ar + Ne plasma is close to 40 % and remains constant across the film thickness. Conversely, in films deposited in pure Ar plasma, the sp3 content decreases from approximately 30 % to 18 % towards the surface. Ne addition increases the sp3 content by enhancing the carbon ion flux and counteracting the atomic shadowing effect. These findings provide novel insights into the role of Ne in reducing the atomic shadowing effect and improving the overall quality of DLC films, paving the way for their optimized industrial use.

Proton and carbon ion radiotherapy for operable early-stage lung cancer; a prospective nationwide registry

Background and purposeTo investigate the toxicity and survival outcomes of proton and carbon ion radiotherapy for patients with operable early-stage lung cancer who are eligible for lobectomy. Materials and methodsThis multicenter nationwide prospective cohort study included patients with operable early-stage lung cancer. Proton and carbon ion radiotherapy was performed according to the schedule stipulated in the unified treatment policy. Progression-free survival (PFS), overall survival (OS) and treatment-related toxicities were evaluated. ResultsA total of 274 patients were enrolled and included in efficacy and safety analyses. The most common tumor type was adenocarcinoma (44 %), while 105 cases (38 %) were not histologically confirmed or diagnosed clinically. Overall, 250 (91 %) of the 274 patients had tumors that were peripherally situated, while 138 (50 %) and 136 (50 %) patients were treated by proton and carbon ion radiotherapy, respectively. The median follow-up time for all censored patients was 42.8 months (IQR 36.7–49.0). Grade 3 or severe treatment-related toxicity was observed in 4 cases (1.5 %). Three-year PFS was 80.5 % (95 % CI: 75.7 %–85.5 %) and OS was 92.5 % (95 % CI: 89.3 %–95.8 %). Pathological confirmation and clinical stage were factors significantly associated with PFS, while tumor location and particle-ion type were not. Meanwhile, clinical stage was significantly associated with OS, but pathological confirmation, tumor location, and particle-ion type were not. ConclusionsParticle therapy for operable early-stage lung cancer resulted in excellent 3-year OS and PFS in each subset. In this disease context, proton and carbon ion beam therapies are feasible alternatives to curative surgery.

Towards precise LET measurements based on energy deposition of therapeutic ions in Timepix3 detectors

Objective. There is an increasing interest in calculating and measuring linear energy transfer (LET) spectra in particle therapy in order to assess their impact in biological terms. As such, the accuracy of the particle fluence energy spectra becomes paramount. This study focuses on quantifying energy depositions of distinct proton, helium, carbon, and oxygen ion beams using a silicon pixel detector developed at CERN to determine LET spectra in silicon. Approach. While detection systems have been investigated in this pursuit, the scarcity of detectors capable of providing per-ion data with high spatial and temporal resolution remains an issue. This gap is where silicon pixel detector technology steps in, enabling online tracking of single-ion energy deposition. The used detector consisted of a 300 µm thick silicon sensor operated in partial depletion. Main results. During post-processing, artifacts in the acquired signals were identified and methods for their corrections were developed. Subsequently, a correlation between measured and Monte Carlo-based simulated energy deposition distributions was performed, relying on a two-step recalibration approach based on linear and saturating exponential models. Despite the observed saturation effects, deviations were confined below 7% across the entire investigated range of track-averaged LET values in silicon from 0.77 keV µm−1 to 93.16 keV µm−1. Significance. Simulated and measured mean energy depositions were found to be aligned within 7%, after applying artifact corrections. This extends the range of accessible LET spectra in silicon to clinically relevant values and validates the accuracy and reliability of the measurements. These findings pave the way towards LET-based dosimetry through an approach to translate these measurements to LET spectra in water. This will be addressed in a future study, extending functionality of treatment planning systems into clinical routine, with the potential of providing ion-beam therapy of utmost precision to cancer patients.

Long-term outcomes after particle radiation therapy in patients with nasopharyngeal adenoid cystic carcinoma

BackgroundNasopharyngeal adenoid cystic carcinoma (NACC) is a relatively rare salivary gland tumor that is generally associated with poor outcomes. High-dose radiotherapy is a key treatment for patients with NACC. This study reported the long-term efficacy and safety of particle beam radiation therapy (PBRT) for NACC.Methods and materialsTwenty-six patients with nonmetastatic NACC who received definitive PBRT alone were included in this retrospective study. The majority of patients (92.3%) had locally advanced disease. Twenty-five (96.15%) patients received intensity-modulated proton radiotherapy (IMPT) followed by a carbon ion radiotherapy (CIRT) boost, and one patient received CIRT alone. Overall survival (OS), local control (LC), regional control (RC), and distant metastasis control (DMC) rates were calculated via the Kaplan-Meier method.ResultsThe median follow-up time was 46.95 months for the entire cohort. Seven patients experienced local recurrence, and one patient experience neck lymph node recurrence. The 3- and 4-year OS, LC, RC, and DMC rates were 100% and 91.7%, 92.3% and 84.6%, 95.8% and 87.8%, and 90.2% and 71.3%, respectively. A total of 91.3% of the patients achieved complete remission of gross tumors at 1 year after PBRT. Severe acute toxicity was observed in only two patients. A grade 4 decrease in visual acuity was observed in one patient with orbital apex invasion. No late grade 3 or 5 toxicity was observed.ConclusionDefinitive PBRT provided a satisfactory 4-year OS for patients with locally advanced NACC. The toxicity was acceptable and mild. Further follow-up is necessary to confirm the efficacy and safety of definitive PBRT for patients with NACC.

Effect of chloride binding behavior of cement hydration products on chloride critical value of steel corrosion in the presence of Na+ and Ca2+

To accurately predict the service life of concrete structures, the effect of chloride binding behavior of cement hydration products on steel corrosion should be taken into account. In this study, the steel specimen with cement paste coating were prepared to investigate the effect of chloride binding behavior on steel initial corrosion in the presence of Na+ and Ca2+. The results show that the higher pH level and Ca2+ concentration effectively inhibited the leaching C–S–H, while the Ca2+ increased the Ca/Si ratio of C–S–H, thereby enhancing the physical chloride binding capacity of cement paste coating in the CaCl2-Ns system (the addition of CaCl2 in NaOH solution). This enhancement primarily accounted for the higher critical value (Ccrit) of 0.03 mol/L in the CaCl2-Ns system, surpassing that of specimens exposed to other corrosion solutions, which was 0.01 mol/L. Both chloride ions from NaCl and CaCl2 could partially replace carbonate ions in monocarboaluminate (Mc), indicating that the cation type did not exert significant influence on chemical binding in this study.

The potential of mixed carbon–helium beams for online treatment verification: a simulation and treatment planning study

Objective. Recently, a new and promising approach for range verification was proposed. This method requires the use of two different ion species. Due to their equal magnetic rigidity, fully ionized carbon and helium ions can be simultaneously accelerated in accelerators like synchrotrons. At sufficiently high treatment energies, helium ions can exit the patient distally, reaching approximately three times the range of carbon ions at an equal energy per nucleon. Therefore, the proposal involves adding a small helium fluence to the carbon ion beam and utilizing helium as an online range probe during radiation therapy. This work aims to develop a software framework for treatment planning and motion verification in range-guided radiation therapy using mixed carbon–helium beams. Approach. The developed framework is based on the open-source treatment planning toolkit matRad. Dose distributions and helium radiographs were simulated using the open-source Monte Carlo package TOPAS. Beam delivery system parameters were obtained from the Heidelberg Ion Therapy Center, and imaging detectors along with reconstruction were facilitated by ProtonVDA. Methods for reconstructing the most likely patient positioning error scenarios and the motion phase of 4DCT are presented for prostate and lung cancer sites. Main results. The developed framework provides the capability to calculate and optimize treatment plans for mixed carbon–helium ion therapy. It can simulate the treatment process and generate helium radiographs for simulated patient geometry, including small beam views. Furthermore, motion reconstruction based on these radiographs seems possible with preliminary validation. Significance. The developed framework can be applied for further experimental work with the promising mixed carbon–helium ion implementation of range-guided radiotherapy. It offers opportunities for adaptation in particle therapy, improving dose accumulation, and enabling patient anatomy reconstruction during radiotherapy.

Thermoluminescence response of carbon ion beam irradiated LiCaAlF6: Tb phosphor

Accurate measurement of the dose delivered to patients is crucial in any radiation therapy, including C ion beam radiotherapy, to ensure effective treatment and minimize the risk of damage to healthy tissues. The accessibility of thermoluminescence (TL) - based materials for carbon ion beam dosimetry continues to be constrained. With the aim of this, an investigation has been done to study the TL properties of the Terbium (Tb) doped LiCaAlF6 phosphor following irradiation with C ion beam. The LiCaAlF6: Tb phosphor has been synthesized using melting method in argon gas atmosphere. TL glow curves has been analyzed on exposure to carbon ion beams at energies of 85 MeV and 50 MeV within the fluence range of 109 - 1012 ions/cm2. The TRIM code, relying on Monte Carlo simulation, has been employed to compute parameters such as absorbed dose, ion range, and energy loss. The Tb-doped LiCaAlF6 phosphor exhibits a glow curve structure with distinctly resolved peaks at 130 °C and 325 °C. Notably, the TL intensity has been significantly increased by 105 times than that of undoped LiCaAlF6. This enhancement is attributed to the generation of a high density of Tb-associated defects within the energy band gap. The TL enhancement has been elucidated based on charge compensation mechanism. Further, TL glow curve shape and structure remain consistent across different energies, i.e., 85 and 50 MeV C ion beams, indicating an energy-independent behavior of this phosphor. Nevertheless, the TL intensity at 85 MeV is higher compared to that at 50 MeV. Detailed dosimetry properties have been investigated for 85 MeV C ion beams within the fluence range 2x109-5x1012 ions/cm2. The phosphor exhibits a sublinear dependence against dose for the studied fluence range with no discernible shift in peak position. The favorable outcomes include low fading during the initial days of storage time and batch homogeneity. TL glow curve analysis indicate the formation of trapping level in the range of 0.90–1.72eV within the band gap of the phosphor which are responsible for TL process. The phosphor's simple glow curve structure, minimal fading, consistent batch homogeneity and high stability of the glow curve suggest that the material can be explored for C ion beam dosimetry application.

A quantitative assessment of Geant4 for predicting the yield and distribution of positron-emitting fragments in ion beam therapy

Objective. To compare the accuracy with which different hadronic inelastic physics models across ten Geant4 Monte Carlo simulation toolkit versions can predict positron-emitting fragments produced along the beam path during carbon and oxygen ion therapy. Approach. Phantoms of polyethylene, gelatin, or poly(methyl methacrylate) were irradiated with monoenergetic carbon and oxygen ion beams. Post-irradiation, 4D PET images were acquired and parent 11C, 10C and 15O radionuclides contributions in each voxel were determined from the extracted time activity curves. Next, the experimental configurations were simulated in Geant4 Monte Carlo versions 10.0 to 11.1, with three different fragmentation models—binary ion cascade (BIC), quantum molecular dynamics (QMD) and the Liege intranuclear cascade (INCL++) - 30 model-version combinations. Total positron annihilation and parent isotope production yields predicted by each simulation were compared between simulations and experiments using normalised mean squared error and Pearson cross-correlation coefficient. Finally, we compared the depth of the maximum positron annihilation yield and the distal point at which the positron yield decreases to 50% of peak between each model and the experimental results. Main results. Performance varied considerably across versions and models, with no one version/model combination providing the best prediction of all positron-emitting fragments in all evaluated target materials and irradiation conditions. BIC in Geant4 10.2 provided the best overall agreement with experimental results in the largest number of test cases. QMD consistently provided the best estimates of both the depth of peak positron yield (10.4 and 10.6) and the distal 50%-of-peak point (10.2), while BIC also performed well and INCL generally performed the worst across most Geant4 versions. Significance. The best predictions of the spatial distribution of positron annihilations and positron-emitting fragment production along the beam path during carbon and oxygen ion therapy was obtained using Geant4 10.2.p03 with BIC or QMD. These version/model combinations are recommended for future heavy ion therapy research.

Temperature Effects of Nuclear and Electronic Stopping Power on Si and C Radiation Damage in 3C-SiC.

Silicon carbide has been considered a material for use in the construction of advanced high-temperature nuclear reactors. However, one of the most important design issues for future reactors is the development of structural defects in SiC under a strong irradiation field at high temperatures. To understand how high temperatures affect radiation damage, SiC single crystals were irradiated at room temperature and after being heated to 800 °C with carbon and silicon ions of energies ranging between 0.5 and 21 MeV. The number of displaced atoms and the disorder parameters have been estimated by using the channeling Rutherford backscattering spectrometry. The experimentally determined depth profiles of induced defects at room temperature agree very well with theoretical calculations assuming its proportionality to the electronic and nuclear-stopping power values. On the other hand, a significant reduction in the number of crystal defects was observed for irradiations performed at high temperatures or for samples annealed after irradiation. Additionally, indications of saturation of the crystal defect concentration were observed for higher fluences and the irradiation of previously defected samples.

Aggregation-induced emission active multianalyte sensor: Detection of pH, carbonate, bi-carbonate and nitroaromatics in water

An aggregation-induced emission (AIE) based multi-tasking probe DAAQ (5-(dimethylamino)-N-(9,10-dioxo-9,10-dihydroanthracen-2-yl)naphthalene-1-sulfonamide) has been reported for detecting multiple analytes such as anions (carbonate and bicarbonate ions) and nitroaromatic compounds (2,4-DNP and TNP). Probe DAAQ displayed the photophysical properties of aggregation-induced emission (AIE) in DMSO-water mixture, acidochromism and detected various analytes, making DAAQ a multi-tasking probe. DAAQ respond to carbonate and bicarbonate (CO32− and HCO3−) with a colour change from pale yellow to dark orange. The limit of detections (LOD) was estimated as 0.486 mg/L and 41.35 mg/L for CO32− and HCO3−, respectively. The applications of DAAQ were also explored to detect CO32− ions in water samples collected from various sources and soft drinks. Further, the probe also explored detecting neural aromatic compounds such as 2,4-DNP and TNP by a naked eye colour change and the LODs were calculated as 12.6 µM and 8.19 µM, respectively. DFT calculations were applied for the confirmation binding studies of DAAQ with multiple analytes. The sensing of 2,4-DNP and TNP were achieved through PET with a Turn-Off response. The sensing mechanisms were confirmed with 1H NMR experiments.

The role of [formula omitted] on controlling the pure vaterite transformations

Vaterite calcium carbonate (CaCO3) possesses unique advantages compared to calcite; however, some critical issues need to be addressed, such as vaterite stability. Numerous studies have indicated that NH4+ can promote vaterite formation and prevent its transformation. However, as vaterite is an instantaneous microscopic process that is easy to transform, directly revealing the role of NH4+ in stabilizing vaterite remains challenging in experiments. This research aims to reveal the role of NH4+ in stabilizing vaterite and retarding phase transformations. Vaterite stabilization was investigated at different NH4+ concentrations and characterized by XRD and SEM. The reaction system’s pH, electrical conductivity, and surface tension changes were analyzed in the presence of NH4+. Computational and experimental studies were utilized to determine the role of NH4+ in the stabilization of vaterite. Results revealed that NH4+ can significantly increase the existence time of vaterite in the water solution. The density functional theory (DFT) indicated that the adsorption energy of NH4+ and vaterite (110), (112), and (114) is obviously higher than that of H2O molecules. The molecular dynamics (MD) simulation research shows that NH4+ can replace water molecules on the crystalline surface of vaterite and mainly interact with carbonate ions on the surface of vaterite. The mechanism analysis shows that the inhibitory effect of NH4+ on the phase transformation of vaterite is primarily caused by preventing the dissolution process. This study systematically explains the role of NH4+ in the stability of vaterite and further reveals that NH4+ can not only promote the formation of vaterite but also play a decisive role in inhibiting its phase transition.

Development and verification of an electron Monte Carlo engine for applications in intraoperative radiation therapy.

In preparation of future clinical trials employing the Mobetron electron linear accelerator to deliver FLASH Intraoperative Radiation Therapy (IORT), the development of a Monte Carlo (MC)-based framework for dose calculation was required. To extend and validate the in-house developed fast MC dose engine MonteRay (MR) for future clinical applications in IORT. MR is a CPU MC dose calculation engine written in C++ that is capable of simulating therapeutic proton, helium, and carbon ion beams. In this work, development steps are taken to include electrons and photons in MR are presented. To assess MRs accuracy, MR generated simulation results were compared against FLUKA predictions in water, in presence of heterogeneities as well as in an anthropomorphic phantom. Additionally, dosimetric data has been acquired to evaluate MRs accuracy in predicting dose-distributions generated by the Mobetron accelerator. Runtimes of MR were evaluated against those of the general-purpose MC code FLUKA on standard benchmark problems. MR generated dose distributions for electron beams incident on a water phantom match corresponding FLUKA calculated distributions within 2.3% with range values matching within 0.01mm. In terms of dosimetric validation, differences between MR calculated and measured dose values were below 3% for almost all investigated positions within the water phantom. Gamma passing rate (1%/1mm) for the scenarios with inhomogeneities and gamma passing rate (3%/2mm) with the anthropomorphic phantom, were>99.8% and 99.4%, respectively. The average dose differences between MR (FLUKA) and the measurements was 1.26% (1.09%). Deviations between MR and FLUKA were well within 1.5% for all investigated depths and 0.6% on average. In terms of runtime, MR achieved a speedup against reference FLUKA simulations of about 13 for 10 MeV electrons. Validations against general purpose MC code FLUKA predictions and experimental dosimetric data have proven the validity of the physical models implemented in MR for IORT applications. Extending the work presented here, MR will be interfaced with external biophysical models to allow accurate FLASH biological dose predictions in IORT.

Development and Fabrication of Microdosimeter Arrays Based on Single‐Crystal Diamond Schottky Diodes

The interest in microdosimetry is growing thanks to the advancement in microdosimetric technologies, improving detector performance and reliability. Herein, the fabrication and characterization of a novel diamond‐based microdosimeter are proposed. The microdosimeter consists of an array of single‐crystal diamond Schottky diodes about 1.5 μm thick connected in parallel. The detector prototypes are characterized using the ion beam‐induced charge technique, employing a 6 MeV carbon ions microbeam. Despite a good overall response, the first prototypes are affected by the “bridge effect”: a charge collection beneath the metallic bridges connecting the sensitive volumes (SVs), which alters the energy deposition spectrum. To mitigate the bridge effect, different technological solutions are explored: the selective growth of intrinsic diamond layers and the use of an insulating material such as photoresist. These second prototypes reveal a good SV spatial definition without any charge collection from the bridges and a good response homogeneity within the SVs ranging between 3% and 5% full‐width‐half‐maximum among the different prototypes. While the cell‐like thickness and lateral dimensions of SVs make the diamond microdosimeter array ideal for radiobiological applications, its array configuration can make it highly versatile to perform under different fluence rate conditions in particle therapy.

CO2 microbubbling system for lithium carbonate precipitation

Lithium carbonate (Li2CO3) is becoming increasingly valuable with the growth of the lithium-ion battery industry. For effective Li2CO3 production, the efficient supply of the carbonate source to the solution is crucial. Conventionally, sodium carbonate has been used as the carbonate source; however, the importance of CO2 utilization has been recently recognized. Conventional CO2-based carbonate sourcing exhibits limited efficiency. In this study, we propose a CO2 microbubbling system based on a rotating nozzle for Li2CO3 precipitation. The CO2 micro-bubbling system demonstrated a 1.6 to 1.9 times greater precipitation reaction rate than that of the conventional CO2 bubbling system. This rate enhancement could be attributed to the increased gas-liquid contact surface and greater residence time due to the generation of CO2 microbubbles. Additionally, the Li2CO3 reaction terminated when the pH of the solution dropped below 9.4–9.7 approximately. The re-dissolution of precipitated Li2CO3 occurred below this pH range as bicarbonate ions became the dominant species over carbonate ions. This study successfully demonstrated that CO2 microbubbling technology could be an excellent alternative for carbonate sourcing systems in the Li2CO3 production industry.

Extraction of K2CO3 from empty palm fruit bunch ash and properties analysis

Empty oil palm fruit bunches (EPFB) are the largest solid waste generated from palm oil mills. Accounting for 21-23 % of the total fresh fruit bunches. EFB ash contains K (Potassium) which can be recovered as K2CO3 through extraction. This research aims to recover K2CO3 from empty oil palm fruit bunches (EPFB) as a catalyst raw material because it is alkaline using the K2CO3 extraction method from the ash of empty oil palm fruit bunches (EPFB), which begins with a combustion process at a temperature of 700 oC to obtain ash. Ash extraction was carried out in 2 stages using water as a solvent. The K2CO3 yield from empty palm fruit bunch ash reached 57.28 %. The alkalinity test showed that the K2CO3 content in the solid extract reached 85.91 %. The properties of the ash and K2CO3 produced were analyzed using XRF, XRD and FTIR. The results of XRF analysis show that the potassium content in the ash contains the element K (potassium) which is quite large, namely 71.24 % and after extraction the purity of potassium oxide reaches 97.08 %. XRD analysis of the results of the synthesis of potassium carbonate from empty oil palm fruit bunches showed that the intensity of the material beam was obtained in a 2ϴ pattern which was lower than the intensity pattern of pure potassium carbonate. The results of FTIR analysis show that the spectrum of carbonate ions from the EPFB C-O bend is visible at 1359,879 and 700.75 cm-1 and these results are similaire to the pure carbonate ion vibration mode.

Comparative analysis of reverse osmosis and nanofiltration for the removal of dissolved contaminants in water reuse applications

The increasing demand for drinking water has led to the adoption of unconventional water sources, such as water reuse. Reverse osmosis (RO) and nanofiltration (NF) membranes are effective barriers against trace organic contaminants in potable water reuse applications. However, the use of RO is being challenged by NF, primarily due to NF's potential to achieve similar contaminant removal as RO but with higher productivity and lower energy requirements. This study compares NF and RO membranes in terms of contaminant removal and energy consumption for potable water reuse applications. RO (BW30XFR) and dense and loose NF (NF90 and NF270) membranes were tested in bench-scale systems, and RO (TW30) and NF (NF9) membrane elements were tested in an engineering scale system utilizing UF-filtered reclaimed wastewater. The highest solute passage was observed using NF270 membrane. There was no difference between NF90 and BW30XFR in terms of divalent ion passage, but NF90's total organic carbon and monovalent ion passages were higher. Both NF90 and BW30XFR highly rejected negatively charged trace organic contaminants (TOrCs), though rejections were lower for neutral and positively charged compounds. Furthermore, all compounds were highly rejected in the engineering-scale system by NF9 and TW30. These results highlight the potential of dense NF membranes as an energy-efficient barrier for contaminant removal.

14-3-3σ downregulation sensitizes pancreatic cancer to carbon ions by suppressing the homologous recombination repair pathway.

This study explored the role of 14-3-3σ in carbon ion-irradiated pancreatic adenocarcinoma (PAAD) cells and xenografts and clarified the underlying mechanism. The clinical significance of 14-3-3σ in patients with PAAD was explored using publicly available databases. 14-3-3σ was silenced or overexpressed and combined with carbon ions to measure cell proliferation, cell cycle, and DNA damage repair. Immunoblotting and immunofluorescence (IF) assays were used to determine the underlying mechanisms of 14-3-3σ toward carbon ion radioresistance. We used the BALB/c mice to evaluate the biological behavior of 14-3-3σ in combination with carbon ions. Bioinformatic analysis revealed that PAAD expressed higher 14-3-3σ than normal pancreatic tissues; its overexpression was related to invasive clinicopathological features and a worse prognosis. Knockdown or overexpression of 14-3-3σ demonstrated that 14-3-3σ promoted the survival of PAAD cells after carbon ion irradiation. And 14-3-3σ was upregulated in PAAD cells during DNA damage (carbon ion irradiation, DNA damaging agent) and promotes cell recovery. We found that 14-3-3σ resulted in carbon ion radioresistance by promoting RPA2 and RAD51 accumulation in the nucleus in PAAD cells, thereby increasing homologous recombination repair (HRR) efficiency. Blocking the HR pathway consistently reduced 14-3-3σ overexpression-induced carbon ion radioresistance in PAAD cells. The enhanced radiosensitivity of 14-3-3σ depletion on carbon ion irradiation was also demonstrated in vivo. Altogether, 14-3-3σ functions in tumor progression and can be a potential target for developing biomarkers and treatment strategies for PAAD along with incorporating carbon ion irradiation.

Ocean alkalinity enhancement using sodium carbonate salts does not lead to measurable changes in Fe dynamics in a mesocosm experiment

Abstract. The addition of carbonate minerals to seawater through an artificial ocean alkalinity enhancement (OAE) process increases the concentrations of hydroxide, bicarbonate, and carbonate ions. This leads to changes in the pH and the buffering capacity of the seawater. Consequently, OAE could have relevant effects on marine organisms and in the speciation and concentration of trace metals that are essential for their physiology. During September and October 2021, a mesocosm experiment was carried out in the coastal waters of Gran Canaria (Spain), consisting on the controlled variation of total alkalinity (TA). Different concentrations of carbonate salts (NaHCO3 and Na2CO3) previously homogenized were added to each mesocosm to achieve an alkalinity gradient between Δ0 to Δ2400 µmol L−1. The lowest point of the gradient was 2400 µmol kg−1, being the natural alkalinity of the medium, and the highest point was 4800 µmol kg−1. Iron (Fe) speciation was monitored during this experiment to analyse total dissolved iron (TdFe, unfiltered samples), dissolved iron (dFe, filtered through a 0.2 µm pore size filter), soluble iron (sFe, filtered through a 0.02 µm pore size filter), dissolved labile iron (dFe′), iron-binding ligands (LFe), and their conditional stability constants (KFeL′) because of change due to OAE and the experimental conditions in each mesocosm. Observed iron concentrations were within the expected range for coastal waters, with no significant increases due to OAE. However, there were variations in Fe size fractionation during the experiment. This could potentially be due to chemical changes caused by OAE, but such an effect is masked by the stronger biological interactions. In terms of size fractionation, sFe was below 1.0 nmol L−1, dFe concentrations were within 0.5–4.0 nmol L−1, and TdFe was within 1.5–7.5 nmol L−1. Our results show that over 99 % of Fe was complexed, mainly by L1 and L2 ligands with kFe′L′ ranging between 10.92 ± 0.11 and 12.68 ± 0.32, with LFe ranging from 1.51 ± 0.18 to 12.3 ± 1.8 nmol L−1. Our data on iron size fractionation, concentration, and iron-binding ligands substantiate that the introduction of sodium salts in this mesocosm experiment did not modify iron dynamics. As a consequence, phytoplankton remained unaffected by alterations in this crucial element.