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Despite extensive efforts on studying the decomposition mechanism of HMX under extreme condition, an intrinsic understanding of mechanical and chemical response processes, inducing the initial chemical reaction, is not yet achieved. In this work, the microscopic dynamic response and initial decomposition of β-HMX with (1 0 0) surface and molecular vacancy under shock condition, were explored by means of the self-consistent-charge density-functional tight-binding method (SCC-DFTB) in conjunction with multiscale shock technique (MSST). The evolutions of various bond lengths and charge transfers were analyzed to explore and understand the initial reaction mechanism of HMX. Our results discovered that the C-N bond close to major axes had less compression sensitivity and higher stretch activity. The charge was transferred mainly from the N-NO2 group along the minor axes and H atom to C atom during the early compression process. The first reaction of HMX primarily initiated with the fission of the molecular ring at the site of the C-N bond close to major axes. Further breaking of the molecular ring enhanced intermolecular interactions and promoted the cleavage of C-H and N-NO2 bonds. More significantly, the dynamic response behavior clearly depended on the angle between chemical bond and shock direction.

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The gonadotropin releasing hormone agonist (GnRH-a) long-protocols and the GnRH-antagonist protocols are two commonly used protocols for in vitro fertilization (IVF), but their cost-effectiveness has not been studied, especially in China. A retrospective study involving 1638 individuals in GnRH-a long-protocol and 621 in GnRH-antagonist protocol were conducted and a decision tree model analysis was used to analyze the cost-effectiveness. Both direct and indirect costs were calculated. As a result, during the fresh embryo transplantation cycles, there was no significant difference in the rate of ongoing pregnancy between the two protocols, the average cost of per ongoing pregnancy in the GnRH-antagonist protocol was $ 16970.85, and that in the GnRH-agonist long-protocol was $19902.24. The probability of cumulative ongoing pregnancy per start cycle was estimated at 60.65% for the GnRH-antagonist protocol and 71.6% for the GnRH-agonist long-protocol (P < 0.01). Considering the cumulative ongoing pregnancy rate, the mean costs per ongoing pregnancy were estimated at $8176.76 and at $7595.28 with GnRH-antagonist protocol and GnRH-agonist long protocol, respectively. In conclusion, in fresh embryo transplantation cycle, the GnRH-antagonist protocol has economic advantage. However, the GnRH-agonist long protocol is more cost effective considering the cumulative ongoing pregnancy rate in the fresh embryo and frozen embryo transplantation cycles. According to a World Health Organization (WHO) report, about 48.5 million couples are affected by infertility worldwide in 2010 1. With the refinement and development of assisted reproductive technology (ART), increasing number of infertile couples seek ART. The European Society of Human Reproduction and Embryology (ESHRE) reported that the worldwide number of babies born as a result of ART has reached an estimated total of 8 million since the world's first, Louise Brown, was born in July 1978 2. Up to now, ART is the most important method to treat infertility in the world. Study has shown that cumulative live birth rates are increased with the number of oocytes obtained 3. Therefore, controlled ovarian hyperstimulation (COH) is an important process to obtain a set number of oocytes for IVF. The GnRH-agonists were introduced into IVF in the late 1980s and the GnRH-agonist long-protocol is still the most frequently used protocol in most centers worldwide 4. The basic principle is to use gonadotropin-releasing hormone agonist (GnRH-a) to regulate pituitary and stimulate follicular growth with exogenous gonadotropin hormone, and avoid endogenous luteinizing hormone (LH) surge before oocyte retrieval 5,6. Since 1990s, GnRH antagonists were used in COH, this protocol competitively blocks pituitary GnRH receptors, inducing a rapid, reversible suppression of gonadotrophin secretion and preventing and interrupting LH surges 6-8. The GnRH-antagonist protocol have been widely adopted in IVF due to these advantages.

Cg1458 was recently characterized as a novel soluble oxaloacetate decarboxylase. However, sequence alignment identified that Cg1458 has no similarity with other oxaloacetate decarboxylases and instead belongs to the FAH (fumarylacetoacetate hydrolase) family. Differences in the function of Cg1458 and other FAH proteins may suggest a different catalytic mechanism. To help elucidate the catalytic mechanism of Cg1458, crystal structures of Cg1458 in both the open and closed conformations have been determined for the first time up to a resolution of 1.9 Å (1 Å=0.1 nm) and 2.0 Å respectively. Comparison of both structures and detailed biochemical studies confirmed the presence of a catalytic lid domain which is missing in the native enzyme structure. In this lid domain, a glutamic acid-histidine dyad was found to be critical in mediating enzymatic catalysis. On the basis of structural modelling and comparison, as well as large-scale sequence alignment studies, we further determined that the catalytic mechanism of Cg1458 is actually through a glutamic acid-histidine-water triad, and this catalytic triad is common among FAH family proteins that catalyse the cleavage of the C-C bond of the substrate. Two sequence motifs, HxxE and Hxx…xxE have been identified as the basis for this mechanism.

In this study, a mesoporous α-Fe 2 O 3 /SiO 2 composite with highly ordered mesostructure and large surface area and pore volume was feasibly fabricated via a spontaneous infiltration route by employing the template-containing mesoporous SiO 2 as support. Fe species are highly dispersed in the framework of the SiO 2 with relatively low Fe content. At high Fe content (rFe:Si = 0.12), α-Fe 2 O 3 nanocrystals with an average size of about 50 nm were incorporated in the matrix of the SiO 2 , existing as both framework and extra-framework forms. The synthesized α-Fe 2 O 3 / SiO 2 composite shows a high adsorption capacity (90 mg•g −1 ) and the superior heterogeneous Fenton-like catalytic activity for the removal of 300 mg•L −1 methylene blue from aqueous solutions (removal efficiency = 100%). The α-Fe 2 O 3 /SiO 2 composite also has a remarkable adsorption and catalysis performance in a wide pH range of 3.0−11.0 and exhibits an excellent stability and reusability.