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OBJECTIVE: Among postmenopausal women, oral, ultra-low-dose continuous combined estradiol (E0.5 mg) plus dydrogesterone (D2.5 mg) reduces vasomotor symptoms (VMS). METHODS: This study was a post hoc analysis of data from two phase 3, double-blind studies. Postmenopausal women were randomized 2:1:2 to receive E0.5 mg/D2.5 mg, E1 mg/D5 mg (not included in this analysis) or placebo for 13 weeks (European study), or randomized 1:1 to receive E0.5 mg/D2.5 mg or placebo for 12 weeks (Chinese study). Endpoints assessed in ethnicity subgroups (European and Chinese) included changes from baseline in number of hot flushes, number of moderate-to-severe hot flushes and Menopause Rating Scale (MRS) score. RESULTS: Overall, 579 women were included in the analysis (E0.5 mg/D2.5 mg, n = 288; placebo, n = 291). European and Chinese women receiving E0.5 mg/D2.5 mg experienced greater reductions from baseline in mean daily number of hot flushes and mean daily number of moderate-to-severe hot flushes at week 4, week 8 and end of treatment versus those receiving placebo. Significant improvements in the 'hot flushes, sweating' MRS item score were reported in both European and Chinese women. CONCLUSION: Oral, ultra-low-dose continuous combined 0.5 mg 17ß-estradiol and 2.5 mg dydrogesterone improved VMS compared with placebo in European and Chinese postmenopausal women, with a positive impact on health-related quality of life.
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Objective: To assess the safety and tolerability of ultra-low dose estradiol and dydrogesterone (E0.5 mg/D2.5 mg) among postmenopausal women. Methods: This pooled analysis of data from three clinical studies assessed the effects of continuous combined ultra-low-dose estradiol and dydrogesterone among postmenopausal women. Participants received E0.5 mg/D2.5 mg or placebo for 13 weeks (double-blind, randomized, European study), E0.5 mg/D2.5 mg or placebo for 12 weeks (double-blind, randomized, Chinese study), or E0.5 mg/D2.5 mg for 52 weeks (open-label, European study). Safety outcomes included treatment-emergent adverse events (TEAEs), treatment-emergent serious adverse events (TESAEs), treatment discontinuation due to a TEAE, and adverse events of special interest (AESIs). Results: Overall, 1027 women were included in the pooled analysis (E0.5 mg/D2.5 mg, n = 736; placebo, n = 291). Mean treatment exposure was 288.9 days in the E0.5 mg/D2.5 mg group and 86.6 days in the placebo group. The proportion of women experiencing ≥1 TEAE was similar in the E0.5 mg/D2.5 mg and placebo groups (50.1% vs 49.5%, respectively). TESAEs occurred in 12 (1.6%) women receiving E0.5 mg/D2.5 mg and 9 (3.1%) women receiving placebo. Discontinuation of study treatment was infrequent in both groups (E0.5 mg/D2.5 mg: 1.5%; placebo: 2.4%). The occurrence of breast pain was more common in the E0.5 mg/D2.5 mg group than in the placebo group (2.0% vs 0.3%) as was uterine hemorrhage (6.5% vs 2.4%). The incidence of acne, hypertrichoses and weight increased was similar between groups. Conclusions: Across three studies, ultra-low-dose estradiol plus dydrogesterone was well tolerated among postmenopausal women, with no increase in TEAEs or TESAEs compared with placebo.
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Didrogesterona , Estradiol , Pós-Menopausa , Humanos , Didrogesterona/administração & dosagem , Didrogesterona/efeitos adversos , Feminino , Estradiol/administração & dosagem , Estradiol/efeitos adversos , Pessoa de Meia-Idade , Método Duplo-Cego , Idoso , Terapia de Reposição de Estrogênios/métodos , Terapia de Reposição de Estrogênios/efeitos adversos , Progestinas/administração & dosagem , Progestinas/efeitos adversos , Fogachos/tratamento farmacológicoRESUMO
Recently, the potential dangers of viral infection transmission through water and air have become the focus of worldwide attention, via the spread of COVID-19 pandemic. The occurrence of large-scale outbreaks of dangerous infections caused by unknown pathogens and the isolation of new pandemic strains require the development of improved methods of viruses' inactivation. Viruses are not stable self-sustaining living organisms and are rapidly inactivated on isolated surfaces. However, water resources and air can participate in the pathogens' diffusion, stabilization, and transmission. Viruses inactivation and elimination by adsorption are relevant since they can represent an effective and low-cost method to treat fluids, and hence limit the spread of pathogen agents. This review analyzed the interaction between viruses and carbon-based, oxide-based, porous materials and biological materials (e.g., sulfated polysaccharides and cyclodextrins). It will be shown that these adsorbents can play a relevant role in the viruses removal where water and air purification mostly occurring via electrostatic interactions. However, a clear systematic vision of the correlation between the surface potential and the adsorption capacity of the different filters is still lacking and should be provided to achieve a better comprehension of the global phenomenon. The rationalization of the adsorption capacity may be achieved through a proper physico-chemical characterization of new adsorbents, including molecular modeling and simulations, also considering the adsorption of virus-like particles on their surface. As a most timely perspective, the results on this review present potential solutions to investigate coronaviruses and specifically SARS-CoV-2, responsible of the COVID-19 pandemic, whose spread can be limited by the efficient disinfection and purification of closed-spaces air and urban waters.
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Color images taken by a smartphone camera were used to estimate the rate of advanced photo-oxidation reaction of Direct Red 23 (DR23) azo dye as a model organic pollutant. The red, green, blue color coordinates were tested to quantify the dye. Images of the reaction mixture were taken at specified intervals to obtain kinetic lines and reaction rate constants. Both the reaction rate constant and the final degree of degradation were plotted as functions of the photocatalyst dose and the concentration of H2O2. The smartphone measurements are fully consistent with the reference spectrophotometry data. The maximum degradation efficiency of the DR23 dye was recorded at C0(H2O2) = 2.5 mM and photocatalyst dose equal to 1.0 mg/L. Higher H2O2 concentrations reduce the degradation rate as a result of the side reaction of H2O2 with OH radicals. A two-factor experimental design was used to study the effects of photocatalyst dose and H2O2 concentration with five and seven levels, respectively. The analysis of variance results indicated that the concentration of H2O2 had the greater influence. The smartphone provides quick and easy measurement of the photodegradation rate directly in the solutions without sampling. The proposed approach can be applied under field conditions in wastewater treatment plants.
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Peróxido de Hidrogênio , Poluentes Químicos da Água , Colorimetria , Oxirredução , Smartphone , Titânio , Raios UltravioletaRESUMO
The fast growth in the anthropogenic activities, that involve a wide use of pharmaceuticals, has led to the appearance of new toxic and hazardous chemical compounds, called "emerging pollutants", which could cause unpredictable consequences to the ecosystems. The current review is focused on emerging pollutants occurring in food or air and include caffeine and nicotine, as well as on pharmaceuticals, in particular amoxicillin, and the concerns caused by its wide usage for medical purposes. This review, for the first time, analyzes and discusses the potential risks and implications of caffeine, nicotine and amoxicillin as emerging environmental pollutants, a field that remains underrepresented to date. Both caffeine and nicotine belong to life style compounds, while pharmaceutical amoxicillin is one of the very popular ß-lactam antibiotics used to take care of human and animal infections. The review covers the toxic effect caused by caffeine, nicotine and amoxicillin on humans and animals and describes some of the main adsorbents utilized for their removal (e.g., grape stalk, tea waste, wheat grains, bentonite, activated carbon, acid and base modified grape slurry wastes, graphene oxides, modified graphene oxides, zeolites, etc.). The isotherm and kinetic models for the analysis of caffeine, nicotine and amoxicillin adsorption by different adsorbents are presented. The impact of pH, temperature, adsorbent dosage and thermodynamic studies were deeply analyzed. The review also discusses the mechanism of adsorption for the above-mentioned emerging pollutants, which includes π-π interaction, cation-π bonding, electron-donor and electron-acceptor forces, van der Waals forces, electrostatic interactions, etc. The present review has a potential value for chemists, ecologists, toxicologists, environmental engineers, and other professionals that are involved in environmental protection.
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Águas Residuárias , Poluentes Químicos da Água , Adsorção , Amoxicilina , Cafeína , Ecossistema , Cinética , NicotinaRESUMO
Dydrogesterone is an oral retroprogesterone widely used to treat progesterone deficiencies, including irregular menstrual cycles (MCs). This prospective, non-interventional, single-arm, post-marketing, observational study evaluated the effects of dydrogesterone on MC regularization. Women aged 18-40 years who had been prescribed dydrogesterone to treat irregular MCs due to progesterone deficiency were enrolled across 64 centers in Russia, Ukraine, Kazakhstan and Uzbekistan. Study objectives included: patients reporting ≥1 regular MC during treatment; the number of regular MCs after the end of treatment over a 6-month follow-up (FU) period. In total, 996 women were enrolled. Of those who completed treatment, 946/955 patients (99.1%) achieved ≥1 regular MC. During FU, 680/860 patients (79.1%) maintained ≥6 regular MCs. Patient grading of menstrual pain and anxiety decreased significantly during treatment (p ≤ 0.0001 versus baseline); this persisted during FU. Dydrogesterone was associated with high or very high patient satisfaction (856/955; 89.6%); the clinical response was considered good or excellent in 819/955 patients (85.8%). In total, 16/986 patients (1.6%) reported an adverse event (AE); two had serious AEs (SAEs) (unrelated to treatment) and three discontinued treatment due to non-SAEs. Dydrogesterone therapy was effective in achieving MC regularization and reducing menstrual pain and anxiety, during both treatment and 6-month FU.
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Didrogesterona/uso terapêutico , Distúrbios Menstruais/tratamento farmacológico , Progestinas/uso terapêutico , Adulto , Didrogesterona/farmacologia , Feminino , Humanos , Ciclo Menstrual/efeitos dos fármacos , Progestinas/farmacologia , Estudos Prospectivos , Adulto JovemRESUMO
Chemical modification of the surface of halloysite nanotubes (HNT) by alkalization (with sodium hydroxide (NaOH)) and grafting with silanes (bis(trimethylsilyl)amine (HMDS)) was carried out. The efficiency of the alkalization and grafting process was evaluated by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and the nitrogen adsorption method were used. XRD and FTIR analysis confirmed the formation of bonds of trimethylsilyl groups to the HNT surface which changed the nature of the surface from hydrophilic to hydrophobic. In addition, it was noted that grafting with silanes decreases by 7.2% the specific surface area of the halloysite compared to the alkalized material. High-density polyethylene (HDPE) composites with halloysite (HNT), alkalized halloysite (alk-HNT), and HMDS-modified halloysite (m-HNT) were processed in the molten state in a Brabender mixer chamber. On SEM/EDS micrographs of HDPE composites with silanized HNT, a change in surface characteristics from smooth to ductile was observed. Higher melting point values based on differential scanning calorimetry (DSC) analysis of HDPE composites with 5%wt silanized halloysite in comparison with HNT and alk-HNT of, respectively, 2.2% and 1.4% were found, which indicates a slight beneficial influence of the filler on the quality of ordering of the crystalline phase of the matrix.
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A lab-scale reactor with a fixed-bed hematite catalyst for the effective decomposition of H2O2 and bacteria inactivation was designed. The bactericidal effect is the largest at a low initial bacterial count of 2·103 CFU/L, which is typical for natural surface waters. When using a 5 mM H2O2 solution and a residence time of 104 min, the reduction in the number of E. coli bacteria is about 3.5-log. At a higher initial bacterial count of 1-2·104 CFU/L, a 5 mM H2O2 solution reduces the bacteria number by about 4-log. The H2O2 decomposition follows the log-linear kinetics of a first-order reaction while the bacterial inactivation does not. The kinetics of bacterial inactivation was described using the Weibull model in the modified form: log10(N0/N) = b · tn. The values of the non-linearity parameter n were found to be lower than 1, indicating that bacterial inactivation slows down over time. With increasing initial H2O2 concentration, the rate parameter b increases while the non-linearity parameter n decreases. With increasing temperature, both parameters increase. The stability of the catalyst has been proved by XRD, FTIR, SEM, and ICP-OES. The concentration of iron leaching into water during disinfection is much lower than the limit declared by WHO for iron in drinking water. The results show that technical-grade hematite is a promising Fenton-like catalyst for water disinfection. The fixed-bed reactor can be the basis of the mobile installations for water purification in emergencies.
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Desinfecção , Compostos Férricos , Peróxido de Hidrogênio , Purificação da Água , Peróxido de Hidrogênio/química , Desinfecção/métodos , Cinética , Purificação da Água/métodos , Catálise , Compostos Férricos/química , Escherichia coli/efeitos dos fármacosRESUMO
OBJECTIVE: To explore the distribution of Rotterdam-based PCOS phenotypes and their associations with anthropometric parameters predictive of cardiometabolic risks in Ukrainian referral PCOS women. STUDY DESIGN: It was a cross-sectional study conducted by the Ukrainian Society of Gynecological Endocrinology between September 2021 and January 2022 involving 42 clinics in 10 regional centres representing the major geographical parts of Ukraine. Two hundred obstetrician-gynecologists whose practice facilities corresponded to study criteria were committed to entering records of their PCOS patients aged 20-45 years into the uniform data collection forms. The recorded parameters were: PCOS phenotype with the mandatory assessment of biochemical hyperandrogenism, age, BMI, waist circumference, and hyperandrogenism symptoms. RESULTS: 5254 patients' records were completed. Phenotype A was the most prevalent - 47.7 %, phenotypes B, C, and D were almost equally distributed in the studied population: 17.6 %, 17.4 %, and 17.3 % respectively. The total prevalence of androgenic phenotypes based on the presence of biochemical hyperandrogenism was 82.7 %. The incidence of obesity and hyperandrogenism symptoms, and mean BMI values were higher in phenotypes A and B compared to C and D. At the same time, the presence of 34.1 % and 46.2 % of normal-weight subjects in phenotypes A and B respectively, supports the fact that the excessive BMI is not a universal characteristic of androgenic phenotypes. In younger age groups, phenotypes C and D demonstrated the predominance of normal weight, but in older subgroups, the situation changed: in the age group of 36-45 y.o. compared to 18-25 y.o., the percentage of overweight and obese subjects for the non-classic phenotypes increased more than for the classic ones: C (OR = 3.91, 95 % CI: 2.41-6.38), D (OR = 4.14, 95 % CI: 2.64-6.52), A (OR = 2.30, 95 % CI:1.72-2.08), and B (OR = 2.56, 95 % CI:1.69-3.89). CONCLUSIONS: In thoroughly assessed Ukrainian referral PCOS population the classic phenotypes prevailed as in other clinical cohorts. The classic phenotypes were characterized by the higher rate of adiposity and severity of clinical hyperandrogenism. At the same time, obese, overweight, and normal-weight subjects were present in all phenotypes, and the risk of obesity in non-classic phenotypes was higher in older age groups.
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Hiperandrogenismo , Síndrome do Ovário Policístico , Humanos , Feminino , Idoso , Adulto , Pessoa de Meia-Idade , Síndrome do Ovário Policístico/complicações , Síndrome do Ovário Policístico/epidemiologia , Síndrome do Ovário Policístico/diagnóstico , Hiperandrogenismo/epidemiologia , Estudos Transversais , Sobrepeso/complicações , Sobrepeso/epidemiologia , Ucrânia/epidemiologia , Androgênios , Fenótipo , Obesidade/complicaçõesRESUMO
Vitamin D deficiency (VDD) is a global problem, however, there were no Ukrainian guidelines devoted to its screening, prevention, and treatment, which became the reason for the Consensus creation. This article aimed to present the Consensus of Ukrainian experts devoted to VDD management. Following the creation of the multidisciplinary Consensus group, consent on the formation process, drafting and fine-tuning of key recommendations, and two rounds of voting, 14 final recommendations were successfully voted upon. Despite a recent decrease in VDD prevalence in Ukraine, we recommend raising awareness regarding VDD's importance and improving the strategies for its decline. We recommend screening the serum 25-hydroxyvitamin D (25(OH)D) level in risk groups while maintaining a target concentration of 75-125 nmol/L (30-50 ng/mL). We recommend prophylactic cholecalciferol supplementation (800-2000 IU/d for youthful healthy subjects, and 3000-5000 IU/d for subjects from the risk groups). For a VDD treatment, we recommend a short-term administration of increased doses of cholecalciferol (4000-10,000 IU/d) with 25(OH)D levels monitored after 4-12 weeks of treatment, followed by the use of maintenance doses. Additionally, we recommend assessing serum 25(OH)D levels before antiosteoporotic treatment and providing vitamin D and calcium supplementation throughout the full course of the antiosteoporotic therapy.
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Deficiência de Vitamina D , Adulto , Humanos , Consenso , Deficiência de Vitamina D/diagnóstico , Deficiência de Vitamina D/tratamento farmacológico , Deficiência de Vitamina D/epidemiologia , Colecalciferol , Calcifediol , EtnicidadeRESUMO
Microplastics are one of the most concerning groups of contaminants that pollute most of the surroundings of the Earth. The abundance of plastic materials available in the environment moved the scientific community in defining a new historical era known as Plasticene. Regardless of their minuscule size, microplastics have posed severe threats to the life forms like animals, plants, and other species present in the ecosystem. Ingestion of microplastics could lead to harmful health effects like teratogenic and mutagenic abnormalities. The source of microplastics could be either primary or secondary in which the components of microplastics are directly released into the atmosphere and the breakdown of larger units to generate the smaller molecules. Though numerous physical and chemical techniques are reported for the removal of microplastics, their increased cost prevents the large-scale applicability of the process. Coagulation, flocculation, sedimentation, and ultrafiltration are some of the methods used for the removal of microplastics. Certain species of microalgae are known to remove microplastics by their inherent nature. One of the biological treatment strategies for microplastic removal is the activated sludge strategy that is used for the separation of microplastic. The overall microplastic removal efficiency is significantly high compared to conventional techniques. Thus, the reported biological avenues like the bio-flocculant for microplastic removal are discussed in this review article.
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Microplásticos , Poluentes Químicos da Água , Animais , Plásticos/química , Água , Ecossistema , Poluentes Químicos da Água/análise , Monitoramento AmbientalRESUMO
The cobalt ferrite Fenton catalysts were obtained by the flow co-precipitation method. FTIR, XRD, and Mössbauer spectroscopy confirmed the spinel structure. The crystallite size of the as-synthesized sample is 12 nm, while the samples annealed at 400 and 600 °C have crystallite sizes of 16 and 18 nm, respectively. The as-synthesized sample has a grain size of 0.1-5.0 µm in size, while the annealed samples have grain sizes of 0.5 µm-15 µm. The degree of structure inversion ranges from 0.87 to 0.97. The catalytic activity of cobalt ferrites has been tested in the decomposition of hydrogen peroxide and the oxidation of caffeine. The annealing of the CoFe2O4 increases its catalytic activity in both model reactions, with the optimal annealing temperature being 400 °C. The reaction order has been found to increase with increasing H2O2 concentration. Electromagnetic heating accelerates the catalytic reaction more than 2 times. As a result, the degree of caffeine decomposition increases from 40% to 85%. The used catalysts have insignificant changes in crystallite size and distribution of cations. Thus, the electromagnetically heated cobalt ferrite can be a controlled catalyst in water purification technology.
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Peróxido de Hidrogênio , Purificação da Água , Peróxido de Hidrogênio/química , Cafeína , Óxidos , Cobalto/químicaRESUMO
PURPOSE: Thyroid cancer (TC) is the most common endocrine cancer worldwide, affecting mainly women of reproductive age. However, no data exist about its association with endometrial or uterine disorders. This study aimed to assess the risk of hyperproliferative pathology of the reproductive system in female ТС survivors. METHODS: This was a cross-sectional study of female patients aged 20-45 years diagnosed with papillary TC (PTC) from 1994-2018. Age-matched females with normal thyroid structures served as controls. RESULTS: One hundred and sixteen patients (mean age 36.7±61 years) and 90 age-matched controls were included. PTC survivors demonstrated an increased risk for adenomyosis [odds ratio (OR) 2.5, 95% confidence interval (CI) 1.3-4.8] and endometrial hyperplasia (OR 3.9, 95% CI 1.1-14.3), compared with controls. The risk for adenomyosis was higher after the ten post-operative years (OR 5.3, 95% CI 2.29- 12.05) than during the first 5-10 years (OR 2.3, 95% CI 1.02-5.10) and increased with the number of RAI courses and the degree of TSH suppression. The risk of endometrial hyperplasia was most evident during the first five years post-thyroidectomy (OR 6.0, 95% CI 1.4-25.5), especially in patients with TSH <0.1 mU/L (OR 6.8, 95% CI 1.4-33.28) No difference in uterine leiomyomas or endometrial polyps was found between PTC survivors and controls. CONCLUSIONS: Female PTC survivors are at increased risk of endometrial hyperplasia and adenomyosis compared with those with normal thyroid structures.
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It is well-documented that accumulation of pharmaceutically active compounds (PhACs), such as antibiotics, in aquatic ecosystems is a prominent environmental hazard. Herein, a series of 2D materials-based heterojunctions, conceptualized based on the integration of graphitic carbon nitride (g-C3N4) with tungsten disulfide (WS2), was fabricated through a facile one-step calcination process, and systematically evaluated for eliminating tetracycline (TC) and sulfamethoxazole (SMX) from aqueous matrices. The microstructure, optical properties, and surface chemistry of the as-prepared composites were examined with a range of microscopy and spectroscopy techniques. In comparison with pristine g-C3N4 or bare WS2, the g-C3N4/WS2 material, with optimal WS2 loading, showed significantly improved photocatalytic activity, towards degradation of TC (84%) and SMX (96%), under visible light. Free radical scavenging experiments revealed that superoxide anions and hydroxyl radicals were predominantly responsible for the rapid breakdown of the PhACs. In addition, the dissociation intermediates and residues were identified and the plausible photocatalytic degradation pathways of TC and SMX over the as-constructed 2D/2D heterojunction were discussed. Further, the photocatalysis end products were non-toxic, as inferred via the resazurin cell viability assay, employing Escherichia coli as a model organism. Most importantly, the 2D/2D g-C3N4/WS2 architecture was structurally resilient and exhibited a fairly stable cycling performance for persistent usage in wastewater treatment. The outcomes of this study testify that 2D/2D heterojunction of g-C3N4 fragments and WS2 nanosheets holds great promise for destroying antibiotics or their metabolites, usually present in wastewaters.
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Poluentes Ambientais , Ecossistema , Catálise , Antibacterianos/química , Tetraciclina , Sulfametoxazol , Luz , Preparações FarmacêuticasRESUMO
PURPOSE: Bariatric surgery is very efficacious in treating severe obesity. However, its effect on menstruation and ovulation is currently unknown. The purpose of this study was to assess the effect of gastric sleeve resection (GSR) on menstrual pattern in women with stages III-IV obesity and ovulatory dysfunction compared with conventional management. METHODS: This was a prospective, multicentre, non-randomized trial, in premenopausal women, who fulfilled the criteria for gastric sleeve resection (GSR). Both women with and without polycystic ovary syndrome (PCOS) were evaluated at 3, 6, 9, 12 and 15 months post-surgery. RESULTS: Menstrual cycle irregularities were identified in 122 severely obese women (60 with PCOS; 62 without PCOS). The % total weight loss was greater with GSR than with conventional management (33.4% vs. 3.6% in PCOS; 24.8% vs. 3.6% in non-PCOS, respectively). Intermenstrual interval was shortened towards normal length (≤ 35 days) both in PCOS and non-PCOS GSR groups, by the 6th and 12th post-surgical month, respectively. Furthermore, ovulation at 6 months was achieved in 63.6% of PCOS and 45% of non-PCOS subjects post-GSR, which was higher than in controls (11.1% and 13.6%, respectively; p < 0.05). This percentage rose to 75.7% and 81.8% at 12 and 15 months in PCOS, respectively, but not in the non-PCOS group (55% and 52.5%, respectively; p < 0.05). CONCLUSIONS: Weight reduction after GSR improved menstrual irregularity towards normality in women with severe obesity. Ovulation dysfunction was also resumed in more than half of these patients at 6-15 months. These effects were more evident in women with PCOS.
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Obesidade Mórbida , Síndrome do Ovário Policístico , Feminino , Humanos , Menstruação , Distúrbios Menstruais/cirurgia , Obesidade/complicações , Obesidade/cirurgia , Obesidade Mórbida/cirurgia , Ovulação , Síndrome do Ovário Policístico/complicações , Síndrome do Ovário Policístico/cirurgia , Estudos Prospectivos , Redução de PesoRESUMO
Designing and fabrication of smart hybrid multifunctional materials for energy/fuel production and environmental detoxification is indeed of great significance for sustainable development. Herein, we synthesized a new well-structured S-scheme heterostructure Fe@TiO2/Boron Carbon nitride (FT/BCN) with high performance tetracycline degradation and selective CO2 photo-reduction to CH4. Under visible light irradiation, 96.3% tetracycline was degraded in 60 min using best performing FT30/BCN sample with a high 83.2% total organic carbon removal in 2 h. The tetracycline degradation rate for FT30/BCN composite catalyst was â¼7 times than bare boron carbon nitride (BCN). The impact of reaction parameters as pH, presence of interfering electrolytes, light source and water matrix was also investigated. The FT30/BCN photocatalyst shows dramatic improvement in CO2 photoreduction as exhibited in 24.7 µmol g-1 h-1 CH4 and 2.4 µmol g-1 h-1 CO evolutions with optimal 91.1% CH4 selectivity. Pure BCN shows a poor 39.1% selectivity. Further, effect of alkali activation, CO2/H2O feed ratio, reducing agent and light source onto CH4 production and selectivity was also investigated. The CH4 evolution and selectivity was improved because of enhanced visible light absorption, high adsorption potential, charge carrier separation and high reducing power of photogenerated electrons induced by an effective S-scheme heterojunction between Fe@TiO2 and boron carbon nitride. An S-scheme (step-scheme) charge transfer mechanism is here operative both during tetracycline removal and CO2 reduction. The drug degradation route and photocatalytic mechanism for antibiotic removal and CO2 reduction was also predicted.
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Gases de Efeito Estufa , Antibacterianos , Boro , Dióxido de Carbono , Nitrilas , Tetraciclina , TitânioRESUMO
Cobalt-zinc ferrite nanoparticles were synthesized using environmentally friendly approach with quince extract as a reducing agent. Crystal structure and morphology of the obtained materials were studied by XRD, SEM-EDS, Mössbauer and IR spectroscopy. The synthesized nanoparticles have a cubic spinel structure and crystallite size ranging from 5 to 9 nm. The infrared spectra contain characteristic absorption bands for the MA-O (â¼560 cm-1) and MB-O bonds (â¼420 cm-1). Force constants were calculated for both tetrahedral and octahedral bonds. As the Co content increases, the force constant for the tetrahedral bond increases and the force constant for the octahedral bond decreases. The obtained ferrite nanoparticles have good magnetization as shown by VSM (in the range from 36 to 67 emu/g). Magnetic nanoparticles CoxZn1-xFe2O4 were also tested for induction heating with electromagnetic field. The sample with x (Co) = 0.4 has the highest specific absorption rate. The synthesized samples were tested as adsorbents using the Congo Red dye as model pollutant. The best adsorbent was pure zinc ferrite with the adsorption capacity of 24.7 mg/g. The catalytic activity of the obtained ferrites for the decomposition of H2O2 was studied as well. The most active catalyst was pure cobalt ferrite. Probably, the active centers are octahedral cobalt ions. Thus, the obtained magnetic nanoparticles can be used for the adsorptive removal of pollutants, catalytic decomposition of the H2O2 and low-frequency hyperthermia.
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Recuperação e Remediação Ambiental , Rosaceae , Adsorção , Cobalto/química , Compostos Férricos , Peróxido de Hidrogênio , Extratos Vegetais , Zinco/análiseRESUMO
The magnesium-zinc ferrites Mg1-xZnxFe2O4 (x = 0 1) were studied as magnetic sorbents for environmental applications. Low-temperature Mössbauer spectroscopy was used to determine the distribution of magnesium and ferric ions in the spinel crystal lattice. The influence of Zn content on magnetic parameters was investigated on the basis of VSM data. As the molar ratio of zinc to magnesium increases from 0 to 1, the pHPZC value decreases from 10.5 to 8.9. Langmuir and Freundlich models were used to check whether single-layer or multi-layer adsorption occurs. The adsorption of Cr(VI) and Ni(II) ions is well fitted by the Langmuir equation. To check the physical or chemical nature of the sorption process, the Dubinin-Radushkevich equation was used. It was found that the processes of adsorption of Cr(VI) and Ni(II) ions are of a chemical nature. The best Cr(VI) ion adsorption capacity was found for the Mg0·2Zn0·8Fe2O4 sample (qe = 30.49 mg/g). The percentage of heavy metal removal by the mixed ferrite samples increases with increasing zinc content. The most effective sorbent for Ni(II) removal is the Mg0·4Zn0·6Fe2O4 sample (93.2%). Modeling the antistructure provides deeper insight into the mechanism of heavy metal adsorption. The obtained magnesium-zinc ferrites are promising magnetic adsorbents for removing chromate and nickel ions from the environment.
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Poluentes Químicos da Água , Zinco , Adsorção , Cátions , Cromo , Compostos Férricos , Concentração de Íons de Hidrogênio , Íons , Cinética , Magnésio , Fenômenos Magnéticos , Poluentes Químicos da Água/análise , Zinco/análiseRESUMO
Magnetic magnesium-zinc spinel ferrite Mg1 - xZnxFe2O4 (where x = 0.4, 0.6, and 0.8) was investigated as adsorbent for the efficient removal of Sr(II) ions and salicylic acid (SA) contaminants from aqueous medium. The characterization of ferrites was carried out using XRD, VSM, BET, SEM, and EDS. The surface charge of magnetic adsorbents was measured by the drift method. The determination of SA and Sr(II) ion concentrations in the solution phase was carried out by UFLC and complexometry, respectively. It was shown that varying of the Zn(II) content affected the adsorption capacities of magnesium-zinc ferrites. The increasing of zinc content from x(Zn2+) = 0.4 to x(Zn2+) = 0.6 increased the adsorption of Sr(II) ions from 50 to 65 mg/g, and then it was decreased to 36 mg/g for the sample with x(Zn) = 0.8. The Mg0.4Zn0.6Fe2O4 sample demonstrated the maximum adsorption capacity of 74 mg/g. The adsorption isotherm for Sr(II) was fitted by the Dubinin-Radushkevich, Langmuir, Freundlich, and Sips models. The adsorption kinetics of Sr(II) was analyzed by PFO, PSO, and Elovich models. The adsorption kinetics of SA was also investigated. It was demonstrated that the Mg0.2Zn0.8Fe2O4 sample exhibited 90% removal of salicylic acid from the water solutions. The results demonstrated that magnetic Mg-Zn ferrites with spinel structure are good sorbents for the removal of SA and Sr(II) ions from aqueous solution.
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Poluentes Químicos da Água/análise , Zinco/análise , Adsorção , Compostos Férricos , Concentração de Íons de Hidrogênio , Íons , Cinética , Magnésio , Fenômenos Magnéticos , Ácido Salicílico , TermodinâmicaRESUMO
The effect of Zn-doping in CoFe2O4 nanoparticles (NPs) through chemical co-precipitation route was investigated in term of structural, optical, and magnetic properties. Both XRD and FTIR analyses confirm the formation of cubic spinel phase, where the crystallite size changes with Zn content from 46 to 77 nm. The Scherrer method, Williamson-Hall (W-H) analysis, and size-strain plot method (SSPM) were used to study of crystallite sizes. The TEM results were in good agreement with the results of the SSP method. SEM observations reveal agglomeration of fine spherical-like particles. The optical band gap energy determined from diffuse reflectance spectroscopy (DRS) varies increases from 1.17 to 1.3 eV. Magnetization field loops reveal a ferromagnetic behavior with lower hysteresis loop for higher Zn content. The magnetic properties are remarkably influenced with Zn doping; saturation magnetization (Ms) increases then decreases while both coercivity (HC) and remanent magnetization (Mr) decrease continuously, which was associated with preferential site occupancy and the change in particle size.