Acoustic emission characteristics and damage evolution of basalt by microwave irradiation.

The microwave-assisted rock breaking technology has been proven to be feasible, and has received considerable attention in the field of civil and mining engineering. A copper foil was used to wrap basalt to simulate rock excavation of practical application scenario in this paper. To this end, a multi-mode cavity with an operating frequency of 2.45 GHz was used to conduct microwave irradiation experiments on basalts with different irradiation times and different power. The thermal properties, AE characteristics, and damage evolution process of basalt were studied. The results show that the high heat generated by microwave leads to the development of cracks in the upper part of basalt. The higher the power level, the higher the degree of crack propagation in the sample, the lower the basalt strength, and the more active the AE activity. The fluctuation rule of the b value indicates that the basalt is dominated by small-scale microfractures before failure. High power levels or long irradiation time lead to more microwave-induced cracks participating in the failure process during loading. Compared with unheated basalt, microwave-heating basalt detects the characteristics of the precursor of failure in advance. The AE source location and the nephogram of the maximum principal stress of microwave-treated basalt reflected that the fracture path begins in the upper part of the rock. In addition, the combination of high power level and short irradiation time can achieve the purpose of energy saving.

Analysis of the Chinese Alligator TCRα/δ Loci Reveals the Evolutionary Pattern of Atypical TCRδ/TCRµ in Tetrapods.

Atypical TCRδ found in sharks, amphibians, birds, and monotremes and TCRµ found in monotremes and marsupials are TCR chains that use Ig or BCR-like variable domains (VHδ/Vµ) rather than conventional TCR V domains. These unconventional TCR are consistent with a scenario in which TCR and BCR, although having diverged from each other more than 400 million years ago, continue to exchange variable gene segments in generating diversity for Ag recognition. However, the process underlying this exchange and leading to the evolution of these atypical TCR receptor genes remains elusive. In this study, we identified two TCRα/δ gene loci in the Chinese alligator (Alligator sinensis). In total, there were 144 V, 154 Jα, nine Jδ, eight Dδ, two Cα, and five Cδ gene segments in the TCRα/δ loci of the Chinese alligator, representing the most complicated TCRα/δ gene system in both genomic structure and gene content in any tetrapod examined so far. A pool of 32 VHδ genes divided into 18 subfamilies was found to be scattered over the two loci. Phylogenetic analyses revealed that these VHδ genes could be related to bird VHδ genes, VHδ/Vµ genes in platypus or opossum, or alligator VH genes. Based on these findings, a model explaining the evolutionary pattern of atypical TCRδ/TCRµ genes in tetrapods is proposed. This study sheds new light on the evolution of TCR and BCR genes, two of the most essential components of adaptive immunity.

Nonparaxial propagation of vector vortex beams diffracted by a circular aperture.

In terms of the vectorial Rayleigh-Sommerfeld diffraction integral, the analytical expressions of the arbitrary vector vortex Laguerre-Gaussian beams on the higher-order Poincaré sphere diffracted by a circular aperture propagating in the nonparaxial and paraxial regimes are presented. The cylindrical vector beam, circularly polarized vortex beam, and elliptically polarized vortex beam are viewed as the special cases of our general result. The analyses show that the nonparaxial evolution properties of the apertured vector vortex beams are determined by the waist width, the truncation parameter, the topological charge, and the ellipticity angle.

Analysis of TCRß and TCRγ genes in Chinese alligator provides insights into the evolution of TCR genes in jawed vertebrates.

All jawed vertebrates have four T cell receptor (TCR) chains that are expressed by thymus-derived lymphocytes and play a major role in animal immune defence. However, few studies have investigated the TCR chains of crocodilians compared with those of birds and mammals, despite their key evolutionary position linking amphibians, reptiles, birds and mammals. Here, employing an Alligator sinensis genomic bacterial artificial chromosome (BAC) library and available genome data, we characterized the genomic organization, evolution and expression of TRB and TRG loci in Alligator sinensis. According to the sequencing data, the Alligator sinensis TRB locus spans approximately 500 Kb of genomic DNA containing two D-J-C clusters and 43 V gene segments and is organized as Vß(39)-pJß1-pCß1-pDß1-Dß2- Jß2(12)-Cß2-Vß(4), whereas the TRG locus spans 115 Kb of DNA genomic sequence consisting of 18 V gene segments, nine J gene segments and one C gene segment and is organized in a classical translocon pattern as Vγ(18)-Jγ(9)-Cγ. Moreover, syntenic analysis of TRB and TRG chain loci suggested a high degree of conserved synteny in the genomic regions across mammals, birds and Alligator sinensis. By analysing the cloned TRB/TRG cDNA, we identified the usage pattern of V families in the expressed TRB and TRG. An analysis of the junctions of the recombined VJ revealed the presence of N and P nucleotides in both expressed TRB and TRG sequences. Phylogenetic analysis revealed that TRB and TRG loci possess distinct evolutionary patterns. Most Alligator sinensis V subgroups have closely related orthologues in chicken and duck, and a small number of Alligator sinensis V subgroups have orthologues in mammals, which supports the hypothesis that crocodiles are the closest relatives of birds and mammals. Collectively, these data provide insights into TCR gene evolution in vertebrates and improve our understanding of the Alligator sinensis immune system.

Neurotoxicity associated with exposure to 1-bromopropane in golf-club cleansing workers.

BACKGROUND: 1-Bromopropane (1-BP) is an alternative to ozone-depleting solvent that is used in degreasing, dry cleaning, spray adhesives, and aerosol solvents. Occupational exposure to 1-BP is associated with adverse peripheral sensory, motor, and central nervous system (CNS) effects. We report our Health Hazard and Medical Evaluation of 6 patients with neurotoxicity associated with occupational exposure to 1-BP. Case series and environmental evaluation. Six workers, 1 male and 5 female, were exposed to high ambient 1-BP concentrations while employed in a golf club cleaning factory. 1-BP was identified in the bulk solvent sample used by the workers and confirmed the workers' daily occupational exposure to 1-BP for 3-10 months. The major presenting symptoms were tingling pain, soreness in lower extremities, and paresthesia. N-acetyl-S-(n-propyl)-L-cysteine (AcPrCys), a 1-BP metabolite, was identified by LC/MS/MS in the urine (0.171-1.74 mg/g-Cr) of these workers 5-26 days following 1-BP exposure. DISCUSSION AND CONCLUSION: An occupational outbreak of 1-BP poisoning occurred as a result of recurrent power outages, condenser, and exhaust fans malfunction, and inadequate personal protection. Occupational exposure to 1-BP may result in peripheral neuropathy as well as adverse CNS effects. Urine AcPrCys may be a specific biomarker for 1-BP exposure.

Distribution of endocrine cells in the digestive tract of Alligator sinensis during the active and hibernating period.

The digestive tract is the largest endocrine organ in the body; the distribution pattern of endocrine cells varies with different pathological and physiological states. The aim of the present study was to investigate the distributed density of 5-hydroxytryptamine (5-HT), gastrin (GAS), somatostatin (SS) and vasoactive intestinal peptide (VIP) immunoreactive (IR) cells in the digestive tract of Alligator sinensis during the active and hibernating period by immunohistochemical (IHC) method. The results indicated that 5-HT-IR cells were distributed throughout the entire digestive tract, which were most predominant in duodenum and jejunum. The density increased significantly in stomach and duodenum during hibernation. GAS-IR cells were limited in small stomach and small intestine. The density decreased significantly in small stomach during hibernation, while increased in duodenum. What's more, most of the endocrine cells in duodenum were generally spindle shaped with long cytoplasmic processes ending in the lumen during hibernation. SS-IR cells were limited in stomach and small stomach. The density increased in stomach while decreased in small stomach during hibernation, meanwhile, fewer IR cells occurred in small intestine. VIP-IR cells occurred in stomach and small stomach. The density decreased in small stomach, while increased in stomach during hibernation. These results indicated that the endocrine cells in different parts of digestive tract varied differently during hibernation, their changes were adaptive response to the hibernation.

A general scenario of Hox gene inventory variation among major sarcopterygian lineages.

BACKGROUND: Hox genes are known to play a key role in shaping the body plan of metazoans. Evolutionary dynamics of these genes is therefore essential in explaining patterns of evolutionary diversity. Among extant sarcopterygians comprising both lobe-finned fishes and tetrapods, our knowledge of the Hox genes and clusters has largely been restricted in several model organisms such as frogs, birds and mammals. Some evolutionary gaps still exist, especially for those groups with derived body morphology or occupying key positions on the tree of life, hindering our understanding of how Hox gene inventory varied along the sarcopterygian lineage. RESULTS: We determined the Hox gene inventory for six sarcopterygian groups: lungfishes, caecilians, salamanders, snakes, turtles and crocodiles by comprehensive PCR survey and genome walking. Variable Hox genes in each of the six sarcopterygian group representatives, compared to the human Hox gene inventory, were further validated for their presence/absence by PCR survey in a number of related species representing a broad evolutionary coverage of the group. Turtles, crocodiles, birds and placental mammals possess the same 39 Hox genes. HoxD12 is absent in snakes, amphibians and probably lungfishes. HoxB13 is lost in frogs and caecilians. Lobe-finned fishes, amphibians and squamate reptiles possess HoxC3. HoxC1 is only present in caecilians and lobe-finned fishes. Similar to coelacanths, lungfishes also possess HoxA14, which is only found in lobe-finned fishes to date. Our Hox gene variation data favor the lungfish-tetrapod, turtle-archosaur and frog-salamander relationships and imply that the loss of HoxD12 is not directly related to digit reduction. CONCLUSIONS: Our newly determined Hox inventory data provide a more complete scenario for evolutionary dynamics of Hox genes along the sarcopterygian lineage. Limbless, worm-like caecilians and snakes possess similar Hox gene inventories to animals with less derived body morphology, suggesting changes to their body morphology are likely due to other modifications rather than changes to Hox gene numbers. Furthermore, our results provide basis for future sequencing of the entire Hox clusters of these animals.

Why do Chinese alligators (Alligator sinensis) form bellowing choruses: a playback approach.

Crocodilians are quite vocal relative to other reptile groups, and the alligators are among the most vocal of the crocodilians. The Chinese alligator, Alligator sinensis, is usually solitary but engages in bellowing choruses in certain waters during the mating season. This paper reports the organization of Chinese alligator's bellowing choruses based upon field observations and playback experiments. Alligators of both genders engaged in the choruses, remaining immobile throughout and inclining toward bellowing synchronously (i.e., starting and finishing at about the same time). The choruses lasted about 10 min with abrupt onset and offset. Moreover, playback experiments revealed that both male and female alligators responded equally to bellowing stimuli from the same and opposite sexes and that none of the tested alligators approached the loudspeaker in spite of playback of male or female stimuli. These suggest that Chinese alligators may not bellow to compete for or attract mates during the choruses. Instead, when their ecological behaviors, namely, dispersed inhabitation, multi-copulation, restricted mating season, etc., are considered, we hypothesize that they may synchronize bellows to enhance group detectability for assembling individuals into certain waters for subsequent copulations.

Acoustic signals of Chinese alligators (Alligator sinensis): social communication.

This paper reports the first systematic study of acoustic signals during social interactions of the Chinese alligator (Alligator sinensis). Sound pressure level (SPL) measurements revealed that Chinese alligators have an elaborate acoustic communication system with both long-distance signal-bellowing-and short-distance signals that include tooting, bubble blowing, hissing, mooing, head slapping and whining. Bellows have high SPL and appear to play an important role in the alligator's long range intercommunion. Sounds characterized by low SPL are short-distance signals used when alligators are in close spatial proximity to one another. The signal spectrographic analysis showed that the acoustic signals of Chinese alligators have a very low dominant frequency, less than 500 Hz. These frequencies are consistent with adaptation to a habitat with high density vegetation. Low dominant frequency sound attenuates less and could therefore cover a larger spatial range by diffraction in a densely vegetated environment relative to a higher dominant frequency sound.

[D-loop sequence variation of mitochondrial DNA in captive Chinese alligator].

Chinese alligator, Alligator sinensis, is a critically endangered endemic species under legislative protection in China. Result of recent investigations revealed that number of the alligators was continuously declining in the past 50 years and less than 150 individuals were surviving in the wild until 2000 years. In order to prevent the extinguishing of this species, two breeding farms were set up in early 1980s at Xuanzhou county, Anhui Province and Changxing County, Zhejiang Province respectively. After twenty years of breeding efforts, the number of captive individuals has been brought up to more than 9,000 in total, forming two separate captive subpopulations, Xuanzhou subpopulation (XZSP) and Changxing subpopulation (CXSP). Because of lack of the information regarding genetic diversity of the captive populations, 42 captive individuals including 33 individuals from XZSP and 9 from CXSP were sampled randomly to investigate their genetic status for the strategy in the next protection action. PCR method was adopted for amplification of mitochodrial DNA control region using primers designed in this research. After purification of PCR products, all of amplicons were sequenced directly with ABI BigDye Terminator Cycle Sequencing Ready Reaction Kit and ABI 310 genetic analyzer. Consequently, 5' end of control region with length of 462 base pair was obtained from 39 samples. Sequence alignment shows there is no any variation site in this range of control region among the individuals assayed here, namely only one haplotype of the region shared by these alligators. This result strongly indicates that the population of captive Chinese alligator is in very poor genetic diversity status. Reasons for the losing of genetic diversity in the population are mainly attributed to population depression and number of individual decreasing sharply in the past 50 years. Another factor accounting for the phenomena is the limit of founder number of captive population. Finally, authors proposed three pieces of advice for the genetic conservation of Chinese alligator.