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The electromagnetic simulation can be used to design the macroscopic absorbing structure of the microwave absorbing material. Research indicates that the macrostructure can adjust the impedance matching and electromagnetic properties of the materials, thereby improving the absorption performance. Among them, the honeycomb structure is often used in actual products due to its good absorption characteristics and mechanical properties. Therefore, in this work, the absorption performance of the carbon microsphere material was improved through the honeycomb structure design. The carbon microsphere material is firstly prepared by sintering phenolic resin, which has the advantages of convenient synthesis, high yield, and a narrow absorption bandwidth of 4.4 GHz. Then, through the high frequency structure simulator (HFSS) electromagnetic simulation, the honeycomb structure based on the carbon microspheres was macroscopically designed, achieving a larger 8.3 GHz absorption frequency bandwidth. This research completed the combination of electromagnetic simulation and honeycomb structure, improved the absorption bandwidth of carbon microspheres, and opened up a new way for the further improvement and practical application for traditional absorption materials. [ABSTRACT FROM AUTHOR]

Antimony (Sb) is a toxic pollutant, but data for Sb toxicity to springtails in soil are limited, and the effects of Sb speciation, soil physiochemical properties, and aging time on Sb toxicity have not been investigated. To address this, the effects of Sb on Folsomia candida were evaluated in laboratory studies. The results demonstrated that compared with Sb(III), no significant change in mortality was observed in Sb(V)-treated soil, but the EC50 value for the reproduction was 28-fold higher than that of Sb(III). Sb(III) toxicity was very different in four soils. The LC50 values for the survival were 2325-5107 mg kg−1 in the acute test and 605-2682 mg kg−1 in the chronic test, and the EC50 values for the reproduction were 293-2317 mg kg−1. The toxicity discrepancies were associated with the variations in oxidation potential and sorption capacity among corresponding soils. Toxicity significantly positively correlated with the clay and amorphous iron content but significantly negatively correlated with pH. Long-term aging markedly decreased Sb(III) toxicity, and the EC50 and LC50 values were unexpectedly higher than the highest test concentration in soil aged for 180 days. Sb(III) toxicity was probably modified more by oxidation than by changes in the available Sb fraction during aging. [ABSTRACT FROM AUTHOR]

Single RE3+ (RE = Eu3+, Tb3+, Dy3+, Sm3+) doped Ba2Gd(BO3)2Cl phosphors were synthesized by the high temperature solid state reaction. Spectroscopic properties of Ba2Gd(BO3)2Cl: RE3+ under vacuum ultraviolet (VUV), ultraviolet (UV) light and low-voltage electron beam excitations were investigated. The Ba2Gd(BO3)2Cl: Dy3+ shows a white light emission under VUV, UV light and electron beam excitation, respectively. Upon different excited source excitation, Ba2Gd(BO3)2Cl: Tb3+ shows similar yellowish-green emissions. Ba2Gd(BO3)2Cl: Sm3+ and Ba2Gd(BO3)2Cl: Eu3+ phosphors show bright orange-red and red emitting under VUV, UV light and electron beam excitation. These results indicated that the Ba2Gd(BO3)2Cl: RE3+ phosphors can be considered as a bright multicolor phosphors for multifunctional application, such as Hg-free lamps, PDPs, W-LEDs and FEDs. [ABSTRACT FROM AUTHOR]

A series of novel silicate-based red-emitting K4Ca1−xSi3O9:xEu3+ (x = 0.01-0.30) phosphors were successfully synthesized via a high-temperature solid-state reaction method for the first time. The compounds were crystallized in the cubic structure with the space group Pa3¯. The photoluminescence spectrum of K4CaSi3O9:Eu3+ phosphor shows four peaks assigned to the 5D0-7FJ (J = 0, 1, 2, 3 and 4) transitions of Eu3+ upon 396 nm excitation. Judd-Ofelt intensity parameters and CIE were calculated from the photoluminescence data. The quenching temperature for K4CaSi3O9:0.30Eu3+ was estimated to be above 500 K. The superior thermal stability can be attributed to the rigid structure of the host. The good color saturation and high thermal stability indicate that K4CaSi3O9:Eu3+ phosphor is a potential candidate for light-emitting diodes. [ABSTRACT FROM AUTHOR]

The p53-regulated GADD45 gene is one of the important players in cellular response to DNA damage, and probably involved in the control of cell cycle checkpoint, apoptosis and DNA repair. There are both the p53-dependent and -independent pathways that regulate GADD45 induction. Following ionizing radiation, induction of the GADD45 gene is regulated by p53 through the p53-binding motif located in the third intron of the GADD45 gene. In contrast, GADD45 induction by methyl methanesulfonate (MMS), UV radiation (UV), and medium starvation is independent of p53 status although p53 may contribute to these responses. However, the regulatory elements that control the p53-independent induction of GADD45 remain uncertain. In this report, we have performed detailed analyses to characterize the responsive components that are required for the induction of the GADD45 promoter. We have found that the region between -107 and -62 of the GADD45 promoter is crucial for the induction. Sequence analysis indicates that there are two OCT-1 sites and one CAAT box located in this region. Site-directed mutations of both OCT-1 and CAAT motifs substantially abrogate the induction of the GADD45 promoter by DNA damage. In addition, both Oct-1 protein (binding to OCT-1 site) and NF-YA protein (binding to CAAT box) are induced after cell exposure to DNA damaging agents. Moreover, the Electrophoretic Mobility Shift Assay (EMSA) has demonstrated the direct bindings of Oct-1 and NF-YA proteins to their consensus sequences in the GADD45 promoter. Therefore, these results have presented the novel observation that transcription factors Oct-1 and NF-YA participate in the cellular response to DNA damage and are involved in the regulation of stress-inducible genes. Oncogene (2001) 20, 2683–2690. [ABSTRACT FROM AUTHOR]

Breast cancer susceptibility gene BRCA1 has been implicated in the control of gene regulation and such regulated genes are thought to mediate the biological role of BRCA1. Overexpression of BRCA1 induces GADD45, a p53-regulated and stress-inducible gene. However, the molecular mechanism by which BRCA1 induces the expression GADD45 remains unclear. In this report, we have shown that the GADD45 promoter is strongly activated following expression of wild-type BRCA1. In contrast, both the tumor-derived BRCA1 mutants (p1749R and Y1853insA) and truncated BRCA1 mutant protein (Δ500–1863 BRCA1), which lack transactivation activity, were unable to activate the GADD45 promoter, indicating that the BRCA1-mediated activation of the GADD45 promoter requires normal transcriptional properties of BRCA1. BRCA1 did not induce the c-Jun and c-fos promoters, which rules out a general effect of BRCA1 on other immediate-responsive genes. Expression of the human papillomavirus E6 and the dominant-negative mutant p53 proteins had no effect on the induction of the GADD45 promoter by BRCA1, suggesting that activation of the GADD45 promoter by BRCA1 is independent of cellular p53 function. With the 5′-deletion analysis, the BRCA1-responsive element of the GADD45 promoter was mapped at the region from -121 to -75. Disruption of this region resulted in the abrogation of BRCA1 activation of the GADD45 promoter. Taken together, these results demonstrate that the mechanism by which BRCA1 induces GADD45 is mainly through the transactivation of the GADD45 promoter, further demonstrating the evidence that GADD45 acts as one of the BRCA1-regulated genes. Oncogene (2000) 19, 4050–4057 [ABSTRACT FROM AUTHOR]