Kinetics of Degradation of Eosin Y by One of the Advanced Oxidation Processes (AOPs)—Fenton’s Process

Kinetics of homogeneous degradation of Eosin Y (EY), also known as Acid red 87 (CI 45380), are studied, mostly using Fenton’s process, at 30℃ by monitoring its absorbance at 517 nm (λmax of EY). This process is one of the advanced oxidation processes (AOPs). Mixture of H2O2 and Fe(II) ion in acetate buffer medium (pH 2.74 - 4.56) generates hydroxyl free radicals (?OH) which attack the dye molecules, resulting in degradation of the dye molecules. Results show that the initial rate of EY degradation decreases with the increasing of solution pH because of removal of kinetically important Fe (iron) species through formation of ferric hydroxide. On the other hand, the rate increases with increasing the concentrations of H2O2, Fe(II) and EY at low solution pH. The initial rate increases with increasing of concentration of H2O2 and, subsequently remains unaffected with further increase of its concentration at a constant Fe(II) concentration because of the enhanced scavenging environment created by H2O2 at its higher concentration. The initial rate also increases with increasing of concentration of Fe(II) at a constant H2O2 concentration and remains unaffected with its further increase. EY concentration also enhances the initial rate at low pH. However, the initial rate is significantly enhanced by UV light. This is because of formation of additional hydroxyl radicals through excitation of the dye molecules by UV light. During the period of experiment, EY in aqueous solution alone hardly suffered any degradation. Degradation mechanism of EY by the Fenton and photo-Fenton’s processes is also discussed. Statistical analysis was used to validate the experimental results. Low values of the standard deviation for both the initial rate and % degradation indicated the consistency of the experimental data.

Controlling of weld hot cracks of aluminum alloy sheets by transverse pre-stressing

A new ideological and theoretical model—a technology to control weld hot cracks by transverse compressive pre-stress in the welding of aluminum alloy was put forward,which was further proved by the subsequent self-designed test setup.Experiments are conducted on the fishbone shaped specimen under conventional welding and welding with various pre-stress values.The experimental results turn out that,the initiation rate of the weld hot cracks decreases with increasing values of the compressive pre-stress.When the pre-stress reaches 0.3-0.4 of the yield stress,the cracks even disappear.In mechanical viewpoint,the researches here develop a new way to control weld cracks.

Control of ribosome synthesis in bacteria:the important role of rRNA chain elongation rate

Bacteria growth depends crucially on protein synthesis,which is limited by ribosome synthesis.Ribosomal RNA(rRNA)transcription is the rate-limiting step of ribosome synthesis.It is generally proposed that the transcriptional initiation rate of rRNA operon is the primary factor that controls the r RNA synthesis.In this study,we established a convenient GFP-based reporter approach for measuring the bacterial rRNA chain elongation rate.We showed that the rRNA chain elongation rate of Escherichia coli remains constant under nutrient limitation and chloramphenicol inhibition.In contrast,rRNA chain elongation rate decreases dramatically under low temperatures.Strikingly,we found that Vibrio natriegens,the fastest growing bacteria known,has a 50%higher rRNA chain elongation rate than E.coli,which contributes to its rapid ribosome synthesis.Our study demonstrates that r RNA chain elongation rate is another important factor that affects the bacterial ribosome synthesis capacity.

Kinetics of Soil Potassium Release Under Long-Term Imbalanced Fertilization in Calcareous Soils

Knowledge on potassium ion(K^+) release from soils makes K fertilizer recommendation more efficient and profitable.Kinetics of K^+release under continuous fertilization of no fertilizer(CK), urea(N), triple superphosphate(P), and urea + triple superphosphate(NP) without K fertilizer was investigated in calcareous(chloritic and kaolinitic) soils on the Miandarband Plain in Kermanshah Province of Iran.The results showed that the kinetics of K^+release included an initial reaction and a slow reaction.The phosphateand NH_4^+-induced K^+release followed the same rate process during the rapid(2–192 h) and slow release periods(192–1 090 h).There were no significant differences in the cumulative K^+released from the chloritic and kaolinitic soils among all the treatments.The cumulative K^+released was positively correlated with P adsorption capacity for the chloritic(r = 0.461, P < 0.05) and kaolinitic soils(r = 0.625, P < 0.01), and negatively correlated with K fixation potential for the chloritic(r = 0.720, P < 0.01) and kaolinitic soils(r =-0.513, P < 0.01).There was a significant(P < 0.001) interactive effect of K fixation potential × P adsorption capacity on the cumulative K^+released for both soil groups.The initial release rate(IRR) index(a·b, where a and b are the rate coefficients of the power function equation) for the chloritic soils was significantly(P < 0.05) higher under applications of P and NP than N and CK.The IRR index values among different fertilization treatments were in the order of NP = P > N = CK for the chloritic soils, and N =P > NP > CK for the kaolinitic soils.This study showed that K fixation potential and P adsorption capacities controlled K^+release from soils.This information will be helpful for precise fertilizer recommendations for the studied soils.

Regulation of Torpor in the Gray Mouse Lemur:Transcriptional and Translational Controls and Role of AMPK Signaling

The gray mouse lemur（Microcebus murinus） is one of few primate species that is able to enter daily torpor or prolonged hibernation in response to environmental stresses. With an emerging significance to human health research, lemurs present an optimal model for exploring molecular adaptations that regulate primate hypometabolism. A fundamental challenge is how to effectively regulate energy expensive cellular processes（e.g., transcription and translation） during transitionsto/from torpor without disrupting cellular homeostasis. One such regulatory mechanism is reversible posttranslational modification of selected protein targets that offers fine cellular control without the energetic burden. This study investigates the role of phosphorylation and/or acetylation in regulating key factors involved in energy homeostasis（AMP-activated protein kinase, or AMPK, signaling pathway）, m RNA translation（eukaryotic initiation factor 2a or e IF2 a, eukaryotic initiation factor 4E or e IF4 E, and initiation factor 4E binding protein or 4EBP）, and gene transcription（histone H3） in six tissues of torpid and aroused gray mouse lemurs. Our results indicated selective tissue-specific changes of these regulatory proteins. The relative level of Thr172-phosphorylated AMPKa was significantly elevated in the heart but reduced in brown adipose tissue during daily torpor, as compared to the aroused lemurs, implicating the regulation of AMPK activity during daily torpor in these tissues. Interestingly, the levels of the phosphorylated e IFs were largely unaltered between aroused and torpid animals. Phosphorylation and acetylation of histone H3 were examined as a marker for transcriptional regulation. Compared to the aroused lemurs, level of Ser10-phosphorylated histone H3 decreased significantly in white adipose tissue during torpor, suggesting global suppression of gene transcription. However, a significant increase in acetyl-histone H3 in the heart of torpid lemurs indicated a possible stimulation of transcriptional activity of this tissue. Overall, our study demonstrates that AMPK signaling and posttranslational regulation of selected proteins may play crucial roles in the control of transcription/translation during daily torpor in mouse lemurs.