Primary Radical Research Articles

Photosynthesis of 3-Alkylated Coumarins from Carboxylic Acids Catalyzed by a Na2S-Based Electron Donor-Acceptor Complex.

A simple and practical electron donor-acceptor (EDA) strategy to synthesize various 3-alkylated coumarins from easily available coumarins and naturally abundant carboxylic acids under photocatalyst-, oxidant-, and additive-free and mild conditions is reported. Using Na2S as the catalytic electron donor, a series of primary, secondary, and tertiary carbon radicals can be efficiently generated, and the EDA complex can be regenerated without an alkaline additive.

Preoperative Neutrophil to Lymphocyte Ratio (NLR) Can Predicts High Risk Surgicopathological Features in Patients of Early Stage Cervical Cancer (stage IB to IIA) Treated by Radical Hysterectomy with Pelvic Lymphadenectomy

Introduction: Globally cervical cancer is the 4th most common cancer in females after breast, colorectal, and lung cancer. In patients with early-stage cervical cancer (stage IB-IIA) who have undergone radical hysterectomy, postoperative histopathologic features along with clinical staging predict prognosis and are used for planning further treatment. Neutrophil-lymphocyte ratio (NLR) is a nonspecific marker to predict prognosis. This study aimed to evaluate the predictive values of preoperative values of NLR for high-risk surgical-pathological features identification in patients with early-stage cervical cancer undergoing primary radical hysterectomy with pelvic lymphadenectomy. Methods: This cross-sectional study was carried out in the Department of Gynaecological Oncology at Bangabandhu Sheikh Mujib Medical University (BSMMU) between July 2019 and June 2020 to evaluate the relationship of preoperative NLR with surgical-pathological features of cervical cancer stage IB-IIA who underwent primary radical hysterectomy and pelvic lymph node dissection. A total of fifty cervical cancer patients were enrolled in this study. Their clinical and histopathological findings and complete blood count reports were collected and analyzed. Result: The ROC curve revealed NLR was 2.670 (sensitivity 63%; specificity 91.3%; Areas under the curves 0.801). Surgical pathological analysis showed that NLR was linked to lymphovascular space invasion. Sixty-three percent of patients having NLR >2.670 were 17.85 times more likely to have LVSI. Conclusion: The study findings conclude that high pretreatment NLR was linked to lymphovascular space invasion. Thus NLR can be used preoperatively to predict the prognosis of cancer cervix and triage the patients into monovalent treatment- either surgery or chemoradiation.

Clinical outcomes of revision radical mastoidectomy surgeries to dry ears: A retrospective study.

This study retrospectively investigated the reasons for failure to dry the ear after primary radical mastoidectomy for chronic otitis media. In this retrospective study, we analyzed the main causes of dry ear failure in 43 patients (46 ears) who underwent radical mastoidectomy. We found that inadequate exposure of the mastoid cavity, incomplete removal of pathological tissues, and poor drainage of the surgical cavity were the main reasons for failure of radical mastoidectomy. Lesions in the tympanic ostium of the eustachian tube and incorrect selection of surgical techniques could also cause dry ear failure. Revision surgery based on preoperative temporal bone computed tomography and intraoperative surgical findings could achieve dry ear in 100% of cases and no complications were observed. In patients who underwent tympanoplasty, there was a significant postoperative decrease in the decibel hearing level for the air conduction threshold and air-bone gap ( P < .05). Based on the reasons for failure, the corresponding treatment was undertaken to achieve dry ears during revision surgery.

Comparing the outcomes of robotic assisted radical prostatectomy in black and white men: Experience of a high-volume center.

Global cancer incidence ranks Prostate Cancer (CaP) as the second highest overall, with Africa and the Caribbean having the highest mortality. Previous literature suggests disparities in CaP outcomes according to ethnicity, specifically functional and oncological are suboptimal in black men. However, recent data shows black men achieve post radical prostatectomy (RP) outcomes equivalent to white men in a universally insured system. Our objective is to compare outcomes of patients who self-identified their ethnicity as black or white undergoing RP at our institution. From 2008 to 2017, 396 black and 4929 white patients underwent primary robotic-assisted radical prostatectomy (RARP) with a minimum follow-up of 5 years. Exclusion criteria were concomitant surgery and cancer status not available. A propensity score (PS) match was performed with a 1:1, 1:2, and 1:3 ratio without replacement. Primary endpoints were potency, continence recovery, biochemical recurrence (BCR), positive surgical margins (PSM), and post-operative complications. After PS 1:1 matching, 341 black vs. 341 white men with a median follow-up of approximately 8 years were analyzed. The overall potency and continence recovery at 12 months was 52% vs 58% (p=0.3) and 82% vs 89% (p=0.3), respectively. PSM rates was 13.4 % vs 14.4% (p = 0.75). Biochemical recurrence and persistence PSA was 13.8% vs 14.1% and 4.4% vs 3.2% respectively (p=0.75). Clavien-Dindo complications (p=0.4) and 30-day readmission rates (p=0.5) were similar. In our study, comparing two ethnic groups with similar preoperative characteristics and full access to screening and treatment showed compatible RARP results. We could not demonstrate outcomes superiority in one group over the other. However, this data adds to the growing body of evidence that the racial disparity gap in prostate cancer outcomes can be narrowed if patients have appropriate access to prostate cancer management. It also could be used in counseling surgeons and patients on the surgical intervention and prognosis of prostate cancer in patients with full access to gold-standard screening and treatment.

Highly dispersed g-C3N4 on well-designed three-dimensional porous nanostructured ZrO2 for high-performance photocatalytic degradation and H2 production

A novel polymer-assisted freeze-drying method was adopted for preparing three-dimensional porous nanostructured ZrO2 (3DPZ) with macro self-supporting properties. Then, g-C3N4 was in-situ grown uniformly on the 3DPZ through a gas-solid reaction, forming 3D nanoporous ZrO2/g-C3N4 heterojunctions (3DP/ZC) with different g-C3N4 loadings that retained self-supporting characteristics. The kapp value of Rhodamine B (RhB) degradation and H2 evolution rate of the 3DP/ZC-2 under visible light reached 0.035 min−1 and 1013.1 μmol h−1 g−1, which were 19.6 and 6.6 times higher than pure g-C3N4, respectively. The ZrO2 nanoparticles (ZNps) prepared via freeze-drying, but without polymer precursor, were used as support to form ZrO2/g-C3N4 nanoparticles (ZCNps-2) for comparison study. The RhB degradation rate and H2 evolution rate of the 3DP/ZC-2 under visible light were about 3.7 and 5.3 times higher than ZCNps-2. Their enhanced photocatalytic activity could be attributed to their unique 3D heterointerface with matched energy bands for rapid charge separation and transfer and a hierarchical porous structure for mass transfer and surface reaction processes. The scavenger trapping and ESR measurements confirmed that the primary reactive radicals for degradation were superoxide radical ions (⋅O2−), hydroxyl radicals (⋅OH), and photogenerated holes (h+). The pH-dependent photocatalytic degradation activity originated from the H+-related ⋅OH conversion reaction. Besides, the macro self-supporting nature could provide excellent separability and recyclability, and self-supporting membranes were also constructed and demonstrated as stable and recyclable photocatalysts. This work provides a new routine for designing 3D-heterojunctions as new kinds of functional materials for applications in environmental remediation and green energy production.

MONITORING ASSESSMENT OF THE EFFECT OF TRANSCRANIAL ELECTRICAL STIMULATION ON THE PSYCHO-EMOTIONAL STATE IN THE WOUND PROCESS AFTER SURGICAL INTERVENTIONS IN THE ORAL CAVITY

The Goal is evaluation of the analgesic effect and psychoemotional state of patients against the background of the use of TES therapy in the wound process after dental interventions in patients.&#x0D; Materials and methods We selected two representative clinical groups by age, medical and social status, and the nature of the pathology. The first group (main) included 105 patients, where after primary radical operations; treatment of the wound process was carried out comprehensively with the use of transcranial electrical stimulation (TES). Group II (comparison) consisted of 128 patients who received traditional therapy according to the clinical protocol. In all patients with open wounds, pain syndrome, psychoemotional state, and clinical course of the wound process were evaluated by generally accepted methods.&#x0D; Research results It has been established that long-term pathological processes in stomatological pathology increase both depression and contribute to the development of psychological dysfunction (Table 2). The assessment of the pain syndrome in a comparative aspect was carried out in the main and comparison groups starting from the second day, since the residual effect of painkillers can be observed on the first day. The results are shown in Table 3&#x0D; It follows from our data that a significant decrease in pain syndrome was observed in patients on the background of TES therapy already on the 2nd day after surgical interventions (p &lt; 0.001). And starting from the 3rd day, the pain syndrome had a pronounced tendency to decrease, and on the 5th day in the II and III main groups it was (2.78 ± 0.32 and 1.13 ± 0.08) points. and on the 8th day (1.62 ± 0.08 and 0.80 ± 0.02) points, respectively, which is significantly higher than the comparison group (р &lt; 0.05).&#x0D; The analysis of the psychological state indicates that against the background of TES-therapy, there is a more significant decrease in the level of reactive anxiety, as well as situational and personal anxiety compared to the comparison group, which has a positive effect, as evidenced by clinical observations, on the course of the wound process and wound healing.&#x0D; From the data in Table 4, on the background of TES therapy, there is only a significant decrease in the level of reactive anxiety both in patients of the 1st group, and in the 2nd and 3rd groups compared to patients on the background of traditional treatment.&#x0D; In addition, in the II and III groups, compared to the comparison group, the level of situational anxiety decreased to (31.4 ± 2.3 and 35.0 ± 2.4) points, which almost corresponds to the level of the control group&#x0D; (p &gt; 0.05). Personal anxiety in these groups was at the level of (37.5 ± 4.3 and 39.6 ± 4.1) points, which is significantly higher than the control group (p &lt; 0.05). In the comparison groups, both situational and personal anxiety even on the 5th day of postoperative intervention was significantly higher than the control group (p &lt; 0.05).&#x0D; Conclusions:&#x0D; &#x0D; Timely assessment of pain syndrome and psycho-emotional state before and after dental intervention allows for their timely correction, which has a positive effect on wound healing.&#x0D; The use of TES therapy in the wound process in the complex treatment of the wound process is more effective than traditional therapy in terms of correcting the pain syndrome and psycho-emotional state of patients.&#x0D; High efficiency, lack of negative impact on the human body makes it possible to recommend the TES-therapy method in dental practice.&#x0D;

'Green-to-Green': Iron oxides embedded in lignin-based carbon scaffolds for water remediation via oxidation excluding free-radical pathways.

Advanced oxidation processes (AOP) are a common tool to remove organic compounds from the water cycle. The process is mostly relied on free radicals (i.e., SO4•- and HO•) with high oxidation power in solution. Surface-mediated mechanism could improve this process to prevent undesired quenching of aqueous radicals that widely exists in free radical pathways and alleviate metal leaching through direct electron transfer. In this work, a facile low-temperature pre-treatment combined with pyrolytic strategy was employed to construct a green catalyst with iron oxides embedded in Kraft-lignin derived bio-char (γ-Fe2O3 @KC), upon which radicals stay surface mediated and the activity-stability trade-off is achieved for pollutant degradation. The γ-Fe2O3 @KC is capable of activating PMS to generate non-radical species which are more stable (1O2 and Fe(V)=O) and of enhancing electron transfer efficiency. A surface-bound reactive complex (Catalyst-PMS*) was identified by electrochemical characterization and was discussed with primary surface-bound radical pairs to explain the contradictions between quenching and EPR detection results. We analyzed the γ-Fe2O3 @KC as a PMS-activating catalyst for a wider range of oxidation targets, such as Rhodamine B (∼100%), p-nitrophenol (∼85%), and Ciprofloxacin (∼63%), and found competitive removal efficiencies. The system also shows an encouraging reusability for at least 5 times and high stability at pH 3-9, and the low concentration of iron in γ-Fe2O3 @KC/PMS system implies the carbon scaffold of biochar alleviate the leakage process. The combined findings highlight the applicability in 'green (source) to green (application)' processes using cost-effective and bio-friendly iron@carbon catalysts, where alternative oxidation pathways are activated to play a dominant role for water purification.

Impact of iodide ions on the speciation of radiolytic transients in molten LiCl-KCl eutectic salt mixtures.

The fate of fission-product iodine is critical for the deployment of next generation molten salt reactor technologies, owing to its volatility and biological impacts if it were to be released into the environment. To date, little is known on how ionizing radiation fields influence the redox chemistry, speciation, and transport of iodine in high temperature molten salts. Here we employ picosecond electron pulse irradiation techniques to elucidate for the first time the impact of iodide ions (I-) on the speciation and chemical kinetics of the primary radiation-induced transient radicals generated in molten chloride salt mixtures (eS- and Cl2˙-) as a function of temperature (400-700 °C). In the presence of I- ions (≥ 1 wt% KI in LiCl-KCl eutectic), we find that the transient spectrum following the electron pulse is composed of at least three overlapping species: the eS- and the Cl2˙- and ICl˙- radical anions, for which a deconvoluted spectrum of the latter is reported here for the first time in molten salts. This new transient spectrum was consistent with gas phase density functional theory calculations. The lifetime of the eS- was unaffected by the addition of I- ions. The newly observed interhalogen radical anion, ICl˙-, exhibited a lifetime on the order of microseconds over the investigated temperature range. The associated chemical kinetics indicate that the predominate mechanism of ICl˙- decay is via reaction with the Cl2˙- radical anion. The iodine containing product of this reaction is expected to be ICl2-, which will have implications for the transport of fission-product iodine in MSR technologies.

Current Controversy and Developments Regarding the Cytoreductive Prostatectomy for Oligometastatic Prostate Cancer.

Oligometastatic prostate cancer is a term that is most often used to refer to limited sites of disseminated tumor growth following primary radical prostatectomy (RP) or radiotherapy (RT), while de novo oligometastatic is a term that is used to refer to prostate tumors that have disseminated to limited sites before definitive treatment. In patients with de novo oligometastatic prostate cancer, treatment planning must thus consider the need to manage the primary tumor and the associated distant lesions. Traditionally, resectioning primary metastatic tumors is not thought to offer significant benefits to affected patients while increasing their risk of surgery-related complications. Recent clinical evidence indicates that patients undergoing cytoreductive prostatectomy (CRP) may observe substantial enhancements in overall survival rates while not experiencing a noticeable decline in their quality of life. Nevertheless, based on the current body of evidence, it is deemed inadequate to justify revising clinical guidelines. Consequently, it is not advisable to propose CRP for patients with oligometastatic prostate cancer. The present review was compiled to summarize available data regarding the indications, functional outcomes, and oncological outcomes associated with cytoreductive radical prostatectomy to provide a robust and objective foundation that can be used to better assess the value of this interventional strategy from a clinical perspective.

Electro-assisted catalytic oxidation of flue gas desulfurization-derived magnesium sulfite using cobalt ferrite as catalyst under moderate condition

The catalysts were prepared by supporting cobalt ferrite (CoxFe3−xO4) on the surfaces of sphere mesoporous silica (MCM−41) nanoparticles. The electro-assisted catalytic oxidation of MgSO3 displayed an improved oxidation rate under moderate temperatures. Electric field and CoFe2O4/MCM−41 exhibited a beneficial synergistic effect because the associated MgSO3 oxidation rate is 3.38 times the oxidation rate when only the electric field was present, and 1.83 times the oxidation rate when only the catalyst was present. The cyclic voltammetry results proved that the catalysts reduced the oxidation potential of SO32− in the presence of an electric field, and increased the electron transfer rate in the oxidation. Both the X-ray photoelectron spectroscopy (XPS) characterization and free radical scavenging experiment results indicated that Co2+ served as the initiator in the generation of superoxide ions (O2−·), which was the primary active free radical responsible for the oxidation of SO32−. The electron spin resonance (ESR) spectra showed that the electric field and high current density expedited the production of O2−·. The XPS results convincingly demonstrated that the electric field effectively alleviated the catalyst deterioration, and, as a result, significantly improved the catalyst's recyclability. Lastly, the synergistic mechanism between the electric field and the catalyst in the catalytic oxidation of MgSO3 was explored.

Peculiarities of treatment of patients with complicated forms of the large bowel cancer in conditions of general clinical stationary

Objective. To estimate the structure of complicated forms of colorectal cancer and surgical tactics of treatment in patients with this pathology in conditions of general surgery stationary.&#x0D; Materials and methods. Into the investigation 71 patients were included, treated for complicated forms of colorectal cancer.&#x0D; Results. Primary radical operative interventions were performed in 48 (67.61%) patients, palliative – 18 (25.35%), and symptomatic – 5 (7.04%).&#x0D; Conclusion. The treatment and diagnosis tactics, formatted in the general surgery stationary conditions,leads to certainly high level of morbidity – 45.07% (the complications have occurred in 32 patients),and lethality – 11.27% (8 patients died).

FLASH irradiation does not induce lipid peroxidation in lipids micelles and liposomes

FLASH radiotherapy (FLASH-RT) enables the delivery of ultra-high dose rate (UHDR) radiation to a tumor, increasing the mean dose rate from 0.1 Gy· s−1of conventional radiotherapy (CONV-RT) to 100 Gy· s−1and above. Animal models have demonstrated that FLASH-RT preserves healthy tissues while yielding similar tumor growth delay as conventional irradiation. Despite the promise of FLASH-RT, the physico-chemical and biological mechanisms underlying the FLASH effect are still under investigation. Two mutually non-exclusive hypothesis have been proposed that could explain the FLASH effect: 1) a reduction in radical diffusion due to a higher recombination rate of primary radicals and, 2) a reduction in tissue oxygenation levels able to alter downstream responses to FLASH-RT. In this respect, lipid peroxidation is a chemical reaction consuming oxygen, which might be involved in the FLASH effect. Here we used linoleic acid micelles and phosphatidylcholine (PC) liposomes as a proxy for cell membrane to investigate the lipid peroxidation yield after irradiation with electrons in FLASH and CONV modalities. With this system, we measured significant differences in concentrations of lipid peroxidation endproducts between both modalities of irradiation. The lipid micelles and PC liposomes exhibited enhanced and linear dose-dependent levels of lipid peroxidation with CONV, while FLASH did not induce lipid peroxidation. Lowering the oxygen content from 21 to 4% resulted in a diminution of the lipid peroxidation yield in CONV, but not its complete suppression. The lipid peroxidation yield dropped rapidly when the dose per pulse was increased from 0.008 Gy·pulse−1to 10 Gy·pulse−1, with no lipid peroxidation occurring above 0.2 Gy·pulse−1. Our results are the first to identify the lack of lipid peroxidation after FLASH-RT, and point to lipids as potentially critical target in rationalizing possible mechanisms underlying the FLASH effect across multiple normal tissue sites.

Dominant Dissolved Oxygen-Independent Pathway to Form Hydroxyl Radicals and the Generation of Reactive Chlorine and Nitrogen Species in Breakpoint Chlorination.

Due to the complexities of the interactions between ammonia, chlor(am)ine, and intermediate species such as ONOOH, the radical formation in breakpoint chlorination and the consequential removal of micropollutants remain largely unexplored. In this study, the dominant generation pathway of HO•, as a primary radical in breakpoint chlorination, was examined, and the generations of HO•, reactive chlorine species (RCS), and reactive nitrogen species (RNS) were quantitatively evaluated. A dissolved oxygen (DO)-independent pathway was verified by 18O labeling and contributed over 90% to HO• generation. The commonly believed pathway, the decomposition of ONOOH involving DO, contributed only 7% to HO• formation in breakpoint chlorination. The chlorine to nitrogen (Cl/N) ratio and pH greatly affected the generations and speciations of the reactive species. An optimum Cl/N mass ratio for HO•, Cl2•-, and RNS generations occurred at the breakpoint (i.e., Cl/N mass ratio = 9), whereas excessive free chlorine shifted the radical speciation toward ClO• at Cl/N mass ratios above the breakpoint. Basic conditions inhibited the generations of HO• and RNS but significantly promoted that of ClO•. These findings improved the fundamental understanding of the radical chemistry of breakpoint chlorination, which can be extended to estimate the degradations of micropollutants of known rate constants toward the reactive species with influences from the Cl/N ratio and pH in real-world applications.

Weakly supervised learning for multi-organ adenocarcinoma classification in whole slide images.

The primary screening by automated computational pathology algorithms of the presence or absence of adenocarcinoma in biopsy specimens (e.g., endoscopic biopsy, transbronchial lung biopsy, and needle biopsy) of possible primary organs (e.g., stomach, colon, lung, and breast) and radical lymph node dissection specimen is very useful and should be a powerful tool to assist surgical pathologists in routine histopathological diagnostic workflow. In this paper, we trained multi-organ deep learning models to classify adenocarcinoma in biopsy and radical lymph node dissection specimens whole slide images (WSIs). We evaluated the models on five independent test sets (stomach, colon, lung, breast, lymph nodes) to demonstrate the feasibility in multi-organ and lymph nodes specimens from different medical institutions, achieving receiver operating characteristic areas under the curves (ROC-AUCs) in the range of 0.91 -0.98.

Photocatalytic Alkyl Addition to Access Quaternary Alkynyl α-Amino Esters.

A regioselective alkylation of β,γ-alkynyl-α-imino esters by visible-light photocatalysis has been developed. This method enables 1,2-addition of methyl, primary, secondary, and tertiary alkyl radicals to the conjugated imines under mild conditions to produce a variety of quaternary alkynyl α-amino acid and cyclic amino acid motifs. Alkyl radicals are generated from alkyl bis(catecholato)silicates with an organic photocatalyst. This process is effective under an air atmosphere, providing operational benefits compared to conventional alkylation using organometallic reagents.

Enantioselective Radical Addition to Ketones through Lewis Acid-Enabled Photoredox Catalysis.

Photocatalysis opens up a new window for carbonyl chemistry. Despite a multitude of photochemical reactions of carbonyl compounds, visible light-induced catalytic asymmetric transformations remain elusive and pose a formidable challenge. Accordingly, the development of simple, efficient, and economic catalytic systems is the ideal pursuit for chemists. Herein, we report an enantioselective radical photoaddition to ketones through a Lewis acid-enabled photoredox catalysis wherein the in situ formed chiral N,N'-dioxide/Sc(III)-ketone complex serves as a temporary photocatalyst to trigger single-electron transfer oxidation of silanes for the generation of nucleophilic radical species, including primary, secondary, and tertiary alkyl radicals, giving various enantioenriched aza-heterocycle-based tertiary alcohols in good to excellent yields and enantioselectivities. The results of electron paramagnetic resonance (EPR) and high-resolution mass spectrum (HRMS) measurements provided favorable evidence for the stereocontrolled radical addition process involved in this reaction.

Radical chemistry, degradation mechanism and toxicity evolution of BPA in the UV/chlorine and UV/H2O2

UV-assisted advanced oxidation processes (AOPs) are widely used and studied in degradation of bisphenol A (BPA). However, detailed information on their radical chemistry and degradation mechanisms is still lacking. In this study, degradation of BPA was comparatively evaluated to investigate the radical mechanisms, products and the toxicity variation in UV/chlorine and UV/H2O2 processes. In comparison with UV/H2O2, UV/chlorine had a higher BPA degradation efficiency and higher pH-dependency due to chlorination and the synergy of •OH and RCS. The •OH and Cl• played a pivotal role as the primary radicals in BPA degradation by UV/chlorine process at all pH investigated (6–8). The relative contributions of the secondary radicals ClO• gradually decreased with a variation of pH from 6 to 8 in this process. Presence of HCO3─ and HA inhibited BPA degradation to different extents in UV/chlorine process, while the effect of Cl─ could be neglected. According to the identified transformation products, chlorination (major), hydroxylation and breakage of the isopropylidene chain were BPA decomposition pathways in the UV/chlorine system. In the UV/H2O2 system, only hydroxylation (major) and breakage of the isopropylidene chain occurred. The toxicity analysis, based on the proposed degradation pathways, indicated that the generation of chlorinated products in the UV/chlorine system led to a higher toxicity of the resulting mixture than in the UV/H2O2 system. Although UV/chlorine has an excellent BPA degradation effect and it is cost-effective, the possible environmental risk should be carefully considered when UV/chlorine system is used to remove BPA in real waters.

Could sulfidation enhance the long-term performance of nano-zero valent iron in the peroxymonosulfate activation to degrade 2-chlorobiphenyl?

Sulfidation can enhance the hydrophobicity of nano-zero valent iron (nZVI) and improve its long-term degradation performance in reduction technology. However, whether sulfidation can enhance its long-term performance in sulfate radical-based advanced oxidation processes hasn't been systematically studied. Herein sulfide-modified nZVI (S-nZVI) was prepared by different sulfidation methods and S/Fe ratios. The behavior of S-nZVI on the peroxymonosulfatec (PMS) activation to degrade 2-chlorobiphenyl for continuous 5 rounds was investigated. The results showed that sulfidation couldn't always promote the long-term degradation performance. S-nZVI prepared by one-step sulfidation method with high S/Fe ratio (S-nZVIonestep-7%, S-nZVIonestep-14%) exhibited inferior degradation performance than unmodified nZVI (52.2%). This was because that the electron donor Fe0 was consumed rapidly and the crystalline lepidocrocite accumulated on the surface, thus inhibited PMS activation. In contrast, S-nZVI prepared by post-sulfidation method with high S/Fe ratio (S-nZVIpost-7%, S-nZVIpost-14%) exhibited more Fe0 residual, less FeOx accumulation, and more catalytic Fe2+ regeneration. Consequently, S-nZVIpost exhibited superior degradation capacity (69.3%). Moreover, the radical quenching experiments revealed that the primary free radicals involved in the degradation were transformed from SO4•- to •OH with prolongation of the degradation. Additionally, Fe (IV) contributed to the degradation through non-radical mechanism, especially in the S-nZVIpost-7%/PMS system.

Light-induced damage to photosystem II at a very low temperature (195 K) depends on singlet oxygen.

Photosynthetic organisms, like evergreen plants, may encounter strong light at low temperatures. Light, despite being the energy source of photosynthesis, irreversibly damages photosystem II (PSII). We illuminated plant thylakoid membranes and intact cyanobacterial cells at -78.5°C and assayed PSII activity with oxygen evolution or chlorophyll fluorescence, after thawing the sample. Both UV radiation and visible light damaged PSII of pumpkin (Cucurbita maxima) thylakoids at -78.5°C, but visible-light-induced photoinhibition at -78.5°C, unlike at +20°C, proceeded only in the presence of oxygen. A strong magnetic field that would decrease triplet chlorophyll formation by recombination of the primary radical pair slowed down photoinhibition at -78.5°C, suggesting that singlet oxygen produced via recombination of the primary pair is a major contributor to photoinhibition at -78.5°C. However, a magnetic field did not affect singlet oxygen production at +25°C. Thylakoids of winter leaves of an evergreen plant, Bergenia, were less susceptible to photoinhibition both at -78.5°C and +20°C, contained high amounts of carotenoids and produced little singlet oxygen (measured at +20°C), compared to thylakoids of summer leaves. In contrast, high carotenoid amount and low singlet oxygen yield did not protect a Synechocystis mutant from photoinhibition at -78.5°C. Thylakoids isolated from Arabidopsis thaliana grown under high light, which reduces PSII antenna size, were more resistant than control plants against photoinhibition at -78.5°C but not at +20°C, although carotenoid amounts were similar. The results indicate that visible-light-induced photoinhibition at -78.5°C depends on singlet oxygen, whereas photoinhibition at +20°C is largely independent of oxygen.

An approach on reactive processing of plastic waste

AbstractAn approach on the reactive processing and compatibilization of plastic waste was simulated for the mixture of thermoplastics with the major content in municipal plastic waste: low‐density polyethylene, high‐density polyethylene, polypropylene, polystyrene, poly(vinyl chloride) (PVC), polyethylene terephthalate, polymethyl methacrylate, PA6, and acrylonitrile‐butadiene‐styrene. Peroxide initiators 2,5‐bis(tert‐butylperoxy)‐2,5‐dimethylhexane (L101) and hydrogen peroxide (H2O2) and poly(styrene‐b‐ethylene‐b‐butylene‐b‐styrene) grafted with maleic anhydride (SEBS‐g‐MAH) were used for the reactive processing of polymer blend under optimized conditions (concentration, reaction temperature, and time). The compatibilization was evidenced by “online” monitoring of the melt viscosity during reactive processing of polymer blend and examined by melt volume rate, oscillatory rheology, mechanical testing, and scanning electron microscopy. The effect of selected peroxides on the type of radical reaction was also evidenced for individual thermoplastics. Both L101 and hydrogen peroxide modify the melt viscosity with different effectivity due to different miscibility, decomposition mechanism, and limited reactivity of individual thermoplastics toward primary radicals. Therefore, the efficiency of compatibilization is limited. On the other hand, SEBS‐g‐MAH acts is an “universal” and effective reactive compatibilizer for multicomponent polymeric blend due to combination of covalent and non‐covalent interactions with blended thermoplastics, resulting in the improvement of mechanical properties and morphology of polymer blend.