Manganese–cerium mixed oxides supported on rice husk based activated carbon with high sulfur tolerance for low-temperature selective catalytic reduction of nitrogen oxides with ammonia

A rice husk-derived activated carbon supported manganese–cerium mixed oxide catalyst (Mn–Ce/RAC) was prepared by an impregnation method and tested for the selective catalytic reduction of nitrogen oxides with ammonia (NH₃-SCR). 5 wt% Mn–Ce/RAC catalyst showed the highest activity, yielding nearly 100% NO_x conversion and N₂ selectivity at 240 °C at a space velocity of 30 000 h⁻¹. Compared with commercial activated carbon supported manganese–cerium mixed oxide catalyst (Mn–Ce/SAC), a higher SCR performance with good SO₂ tolerance could be observed in the tested temperature range over the Mn–Ce/RAC catalyst. The characterization results revealed that the Mn–Ce/RAC catalyst had a higher Mn⁴⁺/Mn³⁺ ratio, amount of chemisorbed oxygen and more Brønsted acid sites than the Mn–Ce/SAC catalyst. The XRD analysis indicated that Mn–Ce oxides were highly dispersed on the RAC support. These properties of Mn–Ce/RAC assisted the SCR reaction. Moreover, in situ DRIFTS results demonstrated that sulfate species formation on Mn–Ce/RAC was much less in the presence of SO₂ than that of Mn–Ce/SAC, which might be ascribed to the reduced alkalinity of the catalyst by the presence of SiO₂ in RAC.

A rice husk derived catalyst exhibited high SCR activity and excellent SO₂ + H₂O tolerance.     

Evaluation of toxic and essential elements in whole blood from 0- to 6-year-old children from Jinan,China

ObjectiveThe aim of the study is to evaluate the distribution and correlation of toxic and essential elements in whole blood from 0- to 6-year-old children from Jinan, China.Design and methodsLevels of toxic and essential elements found in the whole blood of 1110 children were analyzed using an atomic absorption spectrometer. Distributions and correlations of trace elements in different age groups were analyzed and compared.ResultsThe overall mean blood lead (Pb) and cadmium (Cd) levels (49.42 ± 20.16 and 1.47 ± 1.08 μg/L, respectively) were relatively stable among different age groups. The prevalence of Pb and Cd intoxication in all children was 1.4% and 0.4%, respectively. Calcium (Ca) levels decreased gradually with age, with an overall concentration of 1.82 ± 0.15 mmol/L. Whole levels of copper (Cu) and magnesium (Mg) were 17.79 ± 4.22 μmol/L and 1.52 ± 0.14 mmol/L, respectively. While 7.6% of all children showed Cu levels below the normal threshold, the levels of Mg were stable in different age groups. Though the overall mean blood zinc (Zn) and iron (Fe) concentrations (59.59 ± 15.15 μmol/L and 7.39 ± 0.74 mmol/L, respectively) gradually increased with age and the overall deficiency levels (59.8% and 59.5%, respectively) decreased with age, Zn and Fe deficiencies were still very common. Significant positive correlations were found when comparing Cu to Zn, Ca, Mg, and Fe; Zn to Mg and Fe; and Mg to Ca and Fe. Additionally, minor positive correlations were found when comparing Pb to Zn and Fe.ConclusionThe degree of Pb and Cd intoxication in all the children studied was low; however, Pb and Cd exposure was still evident. The importance of Ca deficiency and supplementation is well recognized, but the severity of Fe and Zn deficiency is not as well documented.     

High Removal Efficiency of Diatomite-Based X Zeolite for Cu2+ and Zn2+

Diatomite-based X zeolite was obtained and its crystallinity, morphology, and interface properties were investigated by XRD, BET, SEM, EDS, and XRF. The obtained X zeolite possessed a unique meso-microporous structure and showed good ion exchange properties for Cu²⁺ and Zn²⁺. The pseudo-second-order model and Langmuir isotherm model can best describe the adsorption kinetics and isotherms of Cu²⁺ and Zn²⁺, respectively. The maximal adsorption capacities of X zeolite for Cu²⁺ and Zn²⁺ were 146 and 195 mg/g at 323 K, respectively. Meanwhile, the adsorption process for Cu²⁺ and Zn²⁺ were chemical adsorption and ion exchange, respectively. Furthermore, the adsorption data turned out to be an endothermic and spontaneous process. Compared with other reported materials, the adsorption capacity of X zeolite synthesized from diatomite was among the highest. Therefore, it could be a promising adsorbent for the disposal of wastewater that contains metal ions.     

Chest pain in adolescents: distinguishing cardiac from noncardiac causes

Chest pain, a common problem motivating adults to seek medical care, occurs frequently in adolescents. Physicians may embark on a sequence of nonproductive investigations that can be costly and anxietyprovoking for the adolescent and parent. This review attempts to simplify the medical evaluation and management of the young patient with chest pain. Idiopathic chest pain is the most common diagnosis for childhood and adolescent chest pain, accounting for about 40% of cases. Of those cases for which a cause is found, musculoskeletal causes are most common, accounting for at least 20% of chest pain. Hyperventilation or panic disorders account for 10 to 20% of diagnoses. Noncardiac chest pain typically occurs at rest, which is helpful in distinguishing it from cardiac pain. In those with exercise-induced chest pain asthma must be carefully sought. Congenital coronary artery anomalies leading to angina must also be considered in those with exertional chest pain. Although exertional chest pain should raise a red flag, not all exertional chest pain is worrisome; it may simply reflect poor conditioning or an anxious athlete. In these cases a normal cardiac evaluation including a normal treadmill exercise test with or without reproducible chest pain may help provide the reassurance the anxious athlete needs. After eliminating the possibility of a medical illness, the psychiatrist is in a unique position to provide reassurance and counseling because knowledge about recent life events and the adolescent's beliefs about the symptoms may be necessary prerequisites for successful treatment.     

The influence of age on the inducibility of rat liver cytochrome P450IA1 (CYPIA10 and P450IA2 (CYPIA2) mRNAs

The levels of the messenger RNAs for the cytochromes P450IA1 (CYPIA1) and P450IA2 (CYPIA2) were determined in liver cytoplasmic RNA of rats of various ages after maximal induction with either 3-methylcholanthrene or isosafrole and in untreated rats. An increase in the CYPIA1 mRNA levels was observed only after treatment with 3-methylcholanthrene, whereas both 3-methylcholanthrene and isosafrole were able to induce the levels of CYPIA2 mRNA. The study presented here shows that the maximal induction of these 2 mRNAs did not change with age when 3-methylcholanthrene was used as the inducing agent. Isosafrole induction did not yield higher CYPIA1 mRNA levels in young rats but reduced the amount of this mRNA in old animals to levels below the detection limit of our assay. After induction with isosafrole the levels of the CYPIA2 mRNAs in the older age groups were lower than those observed in young rats. It is concluded that with age the responsiveness to cytochrome P450 inducers may change. This change is different for the various cytochrome P450 enzymes and depends on which inducer is used.     

Succession of the microbial community during the process of mechanical and biological pretreatment coupled with a bio-filter for removal of VOCs derived from domestic waste: a field study

Changes in the microbial community can not only reflect the efficiency of waste disposal, but also reveal the effect of odor control during the treatment process. This study aimed to evaluate the removal efficiency of volatile organic compounds (VOCs) by the process of mechanical and biological pretreatment (MBP) coupled with a bio-filter (BF). An interesting phenomenon was found that the VOCs were effectively reduced through the MBP process. To understand the removal mechanism of VOCs, the abundance and diversity of microbial bacteria and fungi in the biological dehydration (BD) process, biological fermentation process, and BF process were explored. The abundance and diversity of microbes in the BF were relatively high, of which the bacteria such as Lactobacillus, Bacillus and Candida were the dominant species for VOCs treatment. The proposed technical process and the positive effects observed in this study indicate that it could be applied to the control of VOCs in the treatment of domestic waste.

Changes in the microbial community can not only reflect the efficiency of waste disposal, but also reveal the effect of odor control during the treatment process.