Research on the Rule of Explosion Shock Wave Propagation in Multi-Stage Cavity Energy-Absorbing Structures

The propagation laws of explosion shock waves and flames in various chambers were explored through a self-built large-scale gas explosion experimental system. The propagation process of shock waves inside the cavity was explored through numerical simulation using Ansys Fluent, and an extended study was conducted on the wave attenuation effect of multiple cavities connected in a series. The findings show that the cavity's length and diameter influenced the weakening impact of shock waves and explosive flames. By creating a reverse shock wave through complicated superposition, the cavity's shock wave weakening mechanism worked. By suppressing detonation creation inside the cavity, the explosive flame was weakened by the cavity's design. The multi-stage cavity exhibited sound-weakening effects on both shock waves and explosive flames, and an expression was established for the relationship between the suppression rate of shock force and the number of cavities. Diffusion cavities 35, 55, 58, and 85 successfully suppressed explosive flames. The multi-stage cavity efficiently reduced the explosion shock wave. The flame suppression rate of the 58-35 diffusion cavity explosion was 93.38%, whereas it was 97.31% for the 58-35-55 cavity explosion. In engineering practice, employing the 58-58 cavity is advised due to the construction area, construction cost, and wave attenuation impact.

A Research Investigation into the Impact of Reinforcement Distribution and Blast Distance on the Blast Resilience of Reinforced Concrete Slabs

Reinforcement is one of the important factors affecting the anti-blast performance of reinforced concrete (RC) slabs. In order to study the impact of different reinforcement distribution and different blast distances on the anti-blast performance of RC slabs, 16 model tests were carried out for RC slab members with the same reinforcement ratio but different reinforcement distribution and the same proportional blast distance but different blast distances. By comparing the failure patterns of RC slabs and the sensor test data, the impact of reinforcement distribution and blast distance on the dynamic response of RC slabs was analyzed. The results show that, under contact explosion and non-contact explosion, the damage degree of single-layer reinforced slabs is more serious than that of double-layer reinforced slabs. When the scale distance is the same, with the increase of distance, the damage degree of single-layer reinforced slabs and double-layer reinforced slabs increases first and then decreases, and the peak displacement, rebound displacement and residual deformation near the center of the bottom of RC slabs gradually increase. When the blast distance is small, the peak displacement of single-layer reinforced slabs is smaller than that of double-layer reinforced slabs. When the blast distance is large, the peak displacement of double-layer reinforced slabs is smaller than that of single-layer reinforced slabs. No matter how large the blast distance, the rebound peak displacement of the double-layer reinforced slabs is smaller, and the residual displacement is larger. The research in this paper provides a reference for the anti-explosion design, construction and protection of RC slabs.

Study on Dynamic and Static Mechanical Properties of Copper-Plated Steel-Fiber-Reinforced Self-Compacting Concrete

The mechanical properties and impact resistance of conventional self-compacting concrete (SCC) need to be further improved. In order to explore the dynamic and static mechanical properties of copper-plated steel-fiber-reinforced self-compacting concrete (CPSFRSCC), the static mechanical properties and dynamic mechanical properties of CPSFRSCC with a different volume fraction of copper-plated steel fiber (CPSF) are tested, and a numerical experiment is carried out to analyze the experimental results. The results show that the mechanical properties of self-compacting concrete (SCC) can be effectively improved by adding CPSF, especially for the tensile mechanical properties. The static tensile strength of CPSFRSCC shows a trend that increases with the increase in the volume fraction of CPSF and then reaches the maximum when the volume fraction of CPSF is 3%. The dynamic tensile strength of CPSFRSCC shows a trend that increases first and then decrease with the increase in the volume fraction of CPSF, and then reaches the maximum when the volume fraction of CPSF is 2%. The results of the numerical simulation show that the failure morphology of CPSFRSCC is closely related to the content of CPSF; with the increase in the volume fraction of CPSF, the fracture morphology of the specimen gradually evolves from complete fracture to incomplete fracture.

Experimental Study on the Effect of Limestone Powder Content on the Dynamic and Static Mechanical Properties of Seawater Coral Aggregate Concrete (SCAC)

The development of island construction concrete can serve as a basis for the development and utilization of island resources. Complying with the principle of using local materials to configure seawater coral aggregate concrete (SCAC) that is able to meet the requirements of island and reef engineering construction could effectively shorten the construction period and cost of island and reef engineering construction. In this paper, quasi-static mechanical experiments and dynamic mechanical experiments were carried out on SCAC with different limestone powder contents. High-speed photography technology and Digital Image Correlation (DIC) were used to monitor the dynamic failure process and strain field of SCAC, and the influence of limestone powder content on the dynamic and static mechanical properties of SCAC was investigated. The results showed that, when the limestone powder content was 20% and 16%, the quasi-static compressive strength and quasi-static tensile strength exhibited the best improvement. Additionally, with increasing limestone powder content, the dynamic tensile strength of SCAC first showed and increasing trend and then a decreasing trend, reaching its maximum value when the limestone powder content was 16%. Moreover, the maximum strain value of SCAC with the same limestone powder content increased with increasing strain rate grade, showing an obvious effect on strain rate.

Experiment Study on the Influence of Density and Confining Pressure on Triaxial Shear Properties of Calcareous Sand

Calcareous sand is one of the main building materials in the construction of islands and reefs, and its shear property is very important for predicting their strength and deformation. However, the correlation research on the shear properties of calcareous sand is limited. In this paper, a series of the triaxial consolidation drainage shear tests of calcareous sand with relative densities (Dr) of 70% and 90% under confining pressures of 100, 200, 400 and 800 kPa were carried out by a triaxial testing apparatus, and the effects of relative density and confining pressure on the deformation and strength characteristics of calcareous sand were analyzed. The results show that the stress-strain curves of calcareous sand show a strain softening characteristic, and both peak deviatoric stress and failure strain increase with confining pressure, but the increase in failure strain is restrained when the confining pressure is larger than 400 kPa. The initial shear modulus of calcareous sand is positively correlated with confining pressure. Additionally, the molar circular envelope of calcareous sand is linear in the range of 100~400 kPa, but it deviates from linear when confining pressure exceeds 400 kPa. The critical state line (CSL) of calcareous sand is nonlinear, with almost the same exponent for calcareous sand with different relative densities. The research results have important reference value for the foundation construction of islands and reefs.

Observation and research of deep underground multi-physical fields-Huainan -848 m deep experiment

Compared with the surface, the deep environment has the advantages of allowing "super-quiet and ultra-clean"-geophysical field observation with low vibration noise and little electromagnetic interference, which are conducive to therealization of long-term and high-precision observation of multi-physical fields, thus enabling the solution of a series of geoscience problems. In the Panyidong Coal Mine, where there are extensive underground tunnels at the depth of 848 m belowsea level, we carried out the first deep-underground geophysical observations, including radioactivity, gravity, magnetic, magne-totelluric, background vibration and six-component seismic observations. We concluded from these measurements that (1) the background of deep subsurface gravity noise in the long-period frequency band less than 2 Hz is nearly two orders ofmagnitude weaker than that in the surface observation environment; (2) the underground electric field is obviously weaker thanthe surface electric field, and the relatively high frequency of the underground field, greater than 1 Hz, is more than two orders of magnitude weaker than that of the surface electric field; the east-west magnetic field underground is approximately the same asthat at the surface; the relatively high-frequency north-south magnetic field underground, below 10 Hz, is at least one order ofmagnitude lower than that at the surface, showing that the underground has a clean electromagnetic environment; (3) in additionto the high-frequency and single-frequency noises introduced by underground human activities, the deep underground spacehas a sig-nificantly lower background vibration noise than the surface, which is very beneficial to the detection of weakearthquake and gravity signals; and (4) the underground roadway support system built with ferromagnetic material interferesthe geomagnetic field. We also found that for deep observation in the "ultra-quiet and ultra-clean" environment, the existinggeophysical equipment and observation technology have problems of poor adaptability and insufficient precision as well asdata cleaning problems, such as the effective separation of the signal and noise of deep observation data. It is also urgent tointerpret and comprehensively utilize these high-precision multi-physics observation data.

ELECTRONIC SUPPLEMENTARY MATERIAL

Supplementary material is available in the online version of this article at 10.1007/s11430-022-9998-2.

Experimental Study on Two-Phase Explosion Suppression of Gas/Pulverized Coal by Explosion Suppressant

Pulverized coal is widely distributed in coal mine roadways, which can enhance the power of a gas explosion. Explosion suppression technology can effectively reduce the explosion power. At present, rock powder shed, a water bag, and ABC powder are widely used in most coal mine explosion suppression technologies. In order to verify the explosion suppression effect of rock powder, water, and ABC powder in the pulverized coal environment, a series of experiments on a suppressing gas/pulverized coal two-phase explosion were carried out with a self-built large-scale gas explosion experimental system. The experimental study in this paper can provide some reference for the improvement of explosion suppression technology in coal mines. In this paper, through the suppression of a secondary explosion, flame, and impact of pulverized coal, the explosion suppression effects of three kinds of explosion suppressants are comprehensively analyzed. The results show that rock powder has a good inhibitory effect on a secondary explosion and flame of pulverized coal, and water has a good inhibitory effect on the shock wave. ABC powder has the best explosion suppression effect; the inhibition of a secondary explosion of pulverized coal is 4.17 times that of rock powder, the inhibition of flame is 4.28 times that of rock powder, and the inhibition of shock wave is 2.24 times that of water.

A high stem to leaf ratio reduced rainfall use efficiency under altered rainfall patterns in a semi-arid grassland in northeast China

Rainfall use efficiency (RUE) is crucial for understanding the changes in grassland productivity due to variations in future rainfall patterns. Recently, numerous studies have been conducted on the relationship between RUE and the amount of rainfall, but there has been little research on the influence of rainfall distribution and the interactive effect of rainfall amounts and distribution on RUE. Here, a simulated rainfall experiment was conducted to evaluate the impacts of rainfall amount (average rainfall amount (R0), 334 mm; decreased (R-) and increased (R+) rainfall amounts, 233 mm and 434 mm, respectively) and dry intervals (comprising 6-day, 9-day, 12-day, 15-day, 18-day and 21-day intervals between rainfall) on productivity and RUE in Leymus chinensis (Trin.) Tzvel., a dominant grass of the Eastern Eurasian Steppe. Our results showed that (1) for biomass production and RUE, moderate extension of dry intervals was conducive to enhancing total biomass production and RUE. The peak values of total biomass and RUE appeared during the 15-day interval for R-, and the 18-day interval for R0 and R+. (2) For biomass allocation, extension of dry intervals decreased the stem to leaf ratio (S/L) and the root to shoot ratio (R/S). (3) Further, the S/L ratio was significantly negatively correlated with RUE. These results suggest that variations in rainfall patterns can alter the RUE by changing the S/L ratio, and finally influence biomass production in L. chinensis. These findings have important implications for understanding and predicting the effect of future climate change on productivity in semi-arid grassland.

Influence of Cavity Width and Powder Filling in a Cavity on Overpressure Evolution Laws and Flame Propagation Characteristics of Methane/Air Explosion

Passive explosion suppression remains an indispensable auxiliary method for gas explosion suppression due to its low cost. To explore a new type of explosion passive suppression technology, three rectangular cavities with different width-diameter ratios were designed and laid in a large-scale methane/air explosion experiment system, and its explosion suppression performance was evaluated by measuring the changes in the explosion flame and shock wave before and after passing through the cavity. The results show that the suppression effect of the cavity is affected by its width. The larger the width-diameter ratio, the faster the attenuation of the flame and shock wave. The cavity-combined aluminum hydroxide powder effectively improves the suppression effect. When the filling amount of the powder is 140 g, the flame is quenched. However, there is an optimal powder filling degree for the suppression of the shock wave in the limited space of the cavity. In the test range, the maximum decay rate of the overpressure and impulse are 49.4 and 39.4%, respectively. This study can provide theoretical guidelines for the suppression of gas explosion.

0200 Trait Mindfulness Moderates the Within-Person Relationship Between Sleep and Pain in Nurses

Introduction

Sleep and pain have a bidirectional relationship in clinical populations; however, we know less about the daily association in non-clinical but potentially vulnerable populations. Nurses are prone to poor sleep and pain symptoms due to work schedules and occupational stress. Implications from mindfulness-based interventions suggest that mindfulness may play a role in improving sleep and subsequently, reducing pain. The current study examined the within-person relationship between sleep and pain in nurses, and whether trait mindfulness moderates the relationship.

Methods

Participants were 60 nurses employed at a cancer hospital (Mage=35.35±11.83, 32% reported pain). For 14 consecutive days, ecological momentary assessment collected participants’ sleep characteristics, pain symptoms (i.e., chest pain, headaches, upset stomach, and other pain), and pain interference with daily activities. Trait mindfulness was measured using the 15-item Mindful Attention Awareness Scale. Multilevel modeling decomposed variances at the between- and within-person levels.

Results

At the between-person level, after controlling for sociodemographic covariates, more frequent insomnia symptoms (β=0.35) or lower sleep sufficiency (β=-0.19) were associated with more pain symptoms (ps<.05). Inversely, individuals with more pain symptoms reported lower sleep sufficiency (β=-0.41, p<.05). At the within-person level, after nights with poorer sleep quality (β=-0.08, p<.01), lower sleep sufficiency (β=-0.08, p<.01), or shorter sleep duration (β =-0.03, p<.05), participants reported more pain symptoms the following day. There were significant interactions of mindfulness with (a) sleep sufficiency predicting pain interference and (b) sleep duration predicting number of pain symptoms, such that the adverse associations of less sufficient and shorter sleep with more pain were more apparent in those with lower mindfulness than those with higher mindfulness.

Conclusion

Although there was a bidirectional association between sleep and pain at the between-person level, sleep was more likely to be the predictor of pain at the within-person level in oncology nurses. The significant moderation by mindfulness suggest that promoting mindfulness among nurses, prone to having poor sleep and pain, may reduce the adverse impact of poor sleep on daily pain.

Support

This work was supported, in part, by the University of South Florida College of Behavioral & Community Sciences Internal Grant Program (PI: Lee, Grant No. 0134930).

0149 Nightly Sleep Characteristics are Associated with Next-Day Mindfulness

Introduction

Previous research shows that insufficient and poor sleep is associated with perceiving more stressors the following day. Sleep may also be associated with daily mindfulness, a state in which one is highly aware and focused on the present moment without evaluating or judging that moment. The association between high mindfulness and better sleep is well-established; yet, less is known about the temporal directionality between sleep and mindfulness. This study examined whether nightly sleep predicts next-day mindfulness, and vice versa.

Methods

Participants were 60 middle-aged adults working as a full-time nurse at a cancer hospital (Mage=35.35±11.83). Using ecological momentary assessments for 14 days, we asked participants about their previous night’s sleep upon waking and participants completed the 5-item state Mindful Attention Awareness Scale an average of 3 times/day. Multilevel modeling examined variance at the between- and within-person levels and tested two temporal directions simultaneously: better sleep predicting mindfulness and mindfulness predicting better sleep.

Results

Daily mindfulness, sleep duration, sleep sufficiency, and sleep quality displayed 34%, 85%, 82%, and 85% within-person variation, respectively. At the within-person level, daily mindfulness was greater on days following longer than usual sleep duration (B=0.39hrs or 23min, p<.01) and greater than usual sleep sufficiency (B=0.26, p<.001). The within-person link between sleep sufficiency and mindfulness remained even after controlling for the strong association of workdays with less sleep sufficiency. Conversely, mindfulness was not predictive of sleep outcomes. At the between-person level, participants who had greater sleep sufficiency and higher sleep quality overall reported greater mindfulness. These associations remained after adjusting for sociodemographics, dayshift vs. nightshift, and workdays vs. non-work days.

Conclusion

Sufficient sleep duration and perceived sleep sufficiency may be antecedents of how mindful individuals are the following day. Future analyses will test whether the daily link between sleep and mindfulness contributes to health outcomes.

Support

This work was supported, in part, by the University of South Florida College of Behavioral & Community Sciences Internal Grant Program (PI: Lee, Grant No. 0134930).

0341 Preliminary Effects of a Music Intervention on Actigraphy-Measured Sleep Among Older Adults with Dementia

Introduction

Music may benefit sleep and daytime alertness by decreasing stress, increasing attention, and potentially, slowing the progression of dementia. This study examined preliminary effects of a group-based music intervention on sleep health among older adults with dementia.

Methods

Participants were older adults with dementia living in an assisted living facility (n=9; Mage=80.11; Mrange=63−89 years). Cohort 1 (n=4) received the intervention in the morning and cohort 2 (n=5) received the intervention in the afternoon. Participants completed a 4-week intervention protocol (12 sessions) along with a one-week actigraphy sleep assessment before and after the intervention. Informed by sleep literature, we constructed a composite sleep health score encompassing Regularity, Satisfaction or quality, Alertness, Timing, Efficiency, and Duration (higher scores indicating more daily sleep problems). Using descriptive statistics and multilevel modeling, we evaluated preliminary effects of the intervention on overall sleep health and each of the sleep dimensions.

Results

Six out of nine participants exhibited a decrease in overall sleep problems at post-intervention. All 4 participants in cohort 1 showed improvement in overall sleep health at post-intervention. Specifically, in cohort 1, participants exhibited a decline in nightly sleep problems, decreased daytime nap duration, and number of naps. In contrast, while two out of five participants in cohort 2 exhibited improvement in overall sleep health, the remainder of the participants exhibited no improvement in daily sleep problems, especially in nap domains. Across cohorts, those younger in age, with vascular dementia, lower weight, and not taking sleep or hypertension related medications tended to respond better to the intervention.

Conclusion

Our preliminary results demonstrate the feasibility and potential benefit of a group-based music intervention in improving overall sleep health among older patients with dementia. Implications for conducting community-based non-pharmacological interventions to improve sleep and daytime functioning among older adults with dementia will be discussed.

Support

This work was supported, in part, by the Florida Department of Health Ed and Ethel Moore Alzheimer’s Disease Research Award (PI: Meng, Grant #9AZ28).

Effects of dietary probiotic supplementation on LXRα and CYP7α1 gene expression, liver enzyme activities and fat metabolism in ducks

1. The objective of this study was to investigate the effects of dietary probiotic supplementation on liver X receptor alpha (LXRα) and cholesterol 7α-hydroxylase (CYP7α1) mRNA levels, protein enzymatic activities and fat metabolism in Cherry Valley Pekin ducks. 2. A total of 750 one-day-old Cherry Valley Pekin ducks were randomly divided into 5 groups with three replicates of 50 ducks each in a completely randomised experiment. Each group was fed on a basal diet supplemented with 0, 500, 1000, 1500 or 2000 mg probiotics/kg. 3. Body rate and feed conversion ratio were highest and abdominal subcutaneous fat % was lowest at 1000 mg probiotic/kg. 4. The mRNA levels of LXRα and CYP7α1 in liver tissue was estimated by RT-PCR; serum triglyceride (TG) and total cholesterol (TC) concentrations were measured by ELISA. 5. The expression levels and enzyme activity of LXRα and CYP7α1 increased in conjunction with decreases in TG and TC concentrations following probiotic supplementation to a maximum at 1000 mg probiotics/kg and decreased thereafter. 6. It is concluded that dietary probiotics can enhance LXRα and CYP7α1 enzyme activities in the liver and reduce lipid concentrations and fat deposition in ducks.

Bio-inspired laminated graphite nanosheets/copper composites

Bio-inspired laminated graphite nanosheets/copper composites with modified mechanical properties.

Establish and verify TSH reference intervals using optimized statistical method by analyzing laboratory-stored data

OBJECTIVE

To establish reference intervals using an optimized statistical method by collecting available laboratory data of thyroid stimulating hormone (TSH), and then to verify with the laboratory-present reference intervals.

METHODS

TSH RIs of the total population and different races, genders, age, source of sample are established through improved Hoffmann and Katayev's method with TSH test results data from Jan 2010 to April 2012 were collected, and finally conduct comparative verification with the laboratory present RIs.

RESULTS

According to the improved method, we get various RIs of different sample populations. On comparing with the laboratory current RI (0.270-4.200 mIU/L) most reference change values (RCV) were within acceptable limits. Only lower limit of Han male, Uygur male and out-patient male populations outwith acceptable limits. On excluding the different values, finally, the new RI by the optimized statistical method is 0.233-4.979 mIU/L. Because the new RI expanded the current RI and was not different from the current RI, it was indicated that new RI could be used to verify the laboratory current RIs and seen as the current RI's confidence interval (CI).

INFERENCE

TSH RIs established by optimized Hoffmann's and Katayev's methods is viable and can be used to verify RIs provided by manufacturers or other laboratories.

Demonstration of a polymorphism in the gene ERCC1 by two DNA sequencing methods

New methodology is important to the advancement of biomedical science. We recently described a polymorphism within exon IV of the ERCC1 gene, which is associated with an approximate 50% decrease in codon usage in some biological systems. In this report we show that this polymorphism can be readily demonstrated by standard manual DNA sequencing, and by a recently developed methodology which relies on spectrophotometric principles. The major advantage of this new methodology is that several-fold more samples can be assessed per unit time, at reduced cost.

Platinum-sensitive and platinum-resistant ovarian cancer tissues show differences in the relationships between mRNA levels of p53, ERCC1 and XPA

We investigated the association between p53 mRNA expression and clinically relevant surrogates of nucleotide excision repair (ERCC1 and XPA) in 28 ovarian cancer specimens. We observed that platinum-resistant tumors showed higher mRNA levels of p53, ERCC1, and XPA than platinum-sensitive tumors; mRNA expression patterns in responders differed substantially from nonresponders; and p53 expression showed a strong correlation with the expression of ERCC1, and of XPA in platinum-sensitive tumor tissues, but not with platinum-resistant tumors. 47% of the mutations from p53 sequence analysis were not related to clinical response to chemotherapy. We conclude that the p53 influence on DNA repair in human malignancy may vary substantially from tumor to tumor, and that such differences are not necessarily related to the mutational status of p53.

Quercetin induces cell-cycle G1 arrest through elevating Cdk inhibitors p21 and p27 in human hepatoma cell line (HepG2)

Quercetin is a flavonoid ubiquitously found in nature. The therapeutic effect of quercetin on human hepatoma cell line (HepG2) was evaluated in this study. Various groups were incubated with different doses of quercetin for 12-, 24-, 48- and 72-h time duration and compared with control groups. Dose- and time-dependent inhibition in HepG2 proliferation was found with quercetin treatment. At 48 h of incubation, 61.78% of the cells were arrested at G(1) phase with 25 microM/l quercetin while 89.62% were arrested at G(1) phase with 50 microM/l quercetin. Furthermore, the results indicate that quercetin increased the content of Cdk inhibitor p21 protein, which was correlated with the elevation in p53 levels during 12 h of incubation. In addition, quercetin also increased the level of Cdk inhibitor p27 protein during 24 h of incubation. From our results it can be concluded that quercetin blocks cell cycle progression at G(1) phase and exerts its growth-inhibitory effect through the increase of Cdk inhibitors p21 and p27 and tumor suppressor p53 in HepG2.

Acousto-optic, point receiver hydrophone probe for operation up to 100 MHz

This work describes the results of initial evaluation of a wideband acousto-optic hydrophone probe designed to operate as point receiver in the frequency range up to 100 MHz. The hydrophone was implemented as a tapered fiber optic (FO) probe sensor with a tip diameter of approximately 7 microm. Such small physical dimensions of the sensor eliminate the need for spatial averaging corrections so that true pressure-time (p-t) waveforms can be faithfully recorded. The theoretical considerations that predicted the FO probe sensitivity to be equal to 4.3 mV/MPa are presented along with a brief description of the manufacturing process. The calibration results that verified the theoretically predicted sensitivity are also presented along with a brief description of the improvements being currently implemented to increase this sensitivity level by approximately 20 dB. The results of preliminary measurements indicate that the fiber optic probes will exhibit a uniform frequency response and a zero phase shift in the frequency range considered. These features might be very useful in rapid complex calibration i.e. determining both magnitude and phase response of other hydrophones by the substitution method. Also, because of their robust design and linearity, these fiber optic hydrophones could also meet the challenges posed by high intensity focused ultrasound (HIFU) and other therapeutic applications. Overall, the outcome of this work shows that when fully developed, the FO probes will be well suited for high frequency measurements of ultrasound fields and will be able to complement the data collected by the current finite aperture piezoelectric PVDF hydrophones.

Vagus nerve stimulation therapy: A research update

Over the past 5 years, and especially within the last year, there has been a rapid expansion of vagus nerve stimulation (VNS)-related preclinical research, as well as clinical studies in indications other than epilepsy. The research advances in understanding VNS are occurring in the midst of a blossoming of other forms of therapeutic brain stimulation, such as electroconvulsive therapy (ECT), transcranial magnetic stimulation (TMS), and deep brain stimulation (DBS). In general, improved understanding of the neurobiological effects of VNS therapy as a function of the different use parameters (frequency, intensity, pulse width, duration, dose) is beginning to guide clinical use and help determine which diseases, in addition to epilepsy, VNS might treat.

Signal-to-noise analysis for detection sensitivity of small absorbing heterogeneity in turbid media with single-source and dual-interfering-source

Previous studies have suggested that the phased-array detection can achieve high sensitivity in detecting and localizing inhomogeneities embedded in turbid media by illuminating with dual interfering sources. In this paper, we analyze the sensitivity of single-source and dual-interfering-source (phased array) systems with signal-to-noise ratio criteria. Analytical solutions are presented to investigate the sensitivity of detection using different degrees of absorption perturbation by varying the size and contrast of the object under similar configurations for single- and dual-source systems. The results suggest that dual-source configuration can provide higher detection sensitivity. The relation between the amplitude and phase signals for both systems is also analyzed using a vector model. The results can be helpful for optimizing the experimental design by combining the advantages of both single- and dual-source systems in object detection and localization.

[Analysis of environmental gradient and community of forest-swamp ecotone in Changbai mountains]

This paper discussed the change pattern between environmental gradients and community structure, productivity and plant diversity of forest-swamp ecotones, and the mechanism forming those community's traits, which could supply a theoretical basis for conserving and managing the biological resources of ecotonal communities. By setting up sample belts along the environmental gradients on three kinds of ecotones between forests and swamps in Changbai Mountains and through investigating initial data and establishing regression models, the authors studied the dynamic pattern of species composition, diameter class and age class of dominant species, plant diversity, community productivity of forest-swamp ecotone communities with environmental gradients. The results showed that the distribution patterns of community structure characteristics, plant diversity and community productivity were consistent with the changes of environmental gradients of forest-swamp ecotones. Along the environmental gradient from swamp to forest, the displace of dominant species happened, and the species number increased by positive exponent. The diameter distribution of trees decreased by inverse curve, and the age class of trees was suited to cubic distribution. The plant diversity increased by quadratic, and the community biomass increased by cubic power curve along the environmental gradients. The above-mentioned results suggested that the relationships between communities and environmental gradients were closely related.

Association between the level of ERCC-1 expression and the repair of cisplatin-induced DNA damage in human ovarian cancer cells

Nucleotide excision repair (NER) is responsible for the repair of platinum-DNA lesions. ERCC-1 is a critical gene within the NER pathway, and cells without a functional ERCC-1 do not repair cisplatin-caused DNA damage. The present study was therefore designed to evaluate the relationship between the expression of ERCC-1 and the repair of cisplatin-induced DNA adducts in human ovarian cancer cells in vitro. One hour exposure of MCAS cells to cisplatin yielded an approximately two-fold increment in the levels of ERCC-1 mRNA and ERCC-1 protein, as determined, respectively, by Northern and Western blottings. In addition, nuclear run-on assay showed that ERCC-1 gene transcription rate was increased to about the same extent as steady-state ERCC-1 mRNA and protein, in response to cisplatin treatment. However, the levels of ERCC-1 mRNA, ERCC-1 protein, and ERCC-1 transcript in MCAS cells are two-fold lower than those in A2780/CP70 cells, as previously reported. Furthermore, the repair of cisplatin-DNA adducts in MCAS cells, as measured by atomic absorption spectrometry, is also nearly two-fold less than that in A2780/CP70 cells, indicating a strong association between the level of ERCC-1 expression and the activity of excision repair in these two human ovarian tumor cell lines. These results suggest that ERCC-1 may be a useful marker to monitor the repair of platinum-DNA damage in tumor cells, and further highlight that potential pharmacological approaches which specifically inhibit ERCC-1 expression may increase cellular sensitivity to cisplatin.

Comparison of two human ovarian carcinoma cell lines (A2780/CP70 and MCAS) that are equally resistant to platinum, but differ at codon 118 of the ERCC1 gene

ERCC1 is an essential gene within the nucleotide excision repair process. We studied two human ovarian carcinoma cell lines for cisplatin resistance, which differed with respect to ERCC1. The A2780/CP70 cell line has been extensively studied previously, and has the wild-type ERCC1 sequence. The MCAS cell line has a recently described ERCC1 polymorphism at codon 118, which is associated with an approximate 50% reduction in codon usage. These cells did not differ with respect to p53 sequence nor p53 mRNA induction following cisplatin exposure. The induction of ERCC1 mRNA was markedly reduced in MCAS cells as compared to A2780/CP70 cells. At the IC50 cisplatin dose for each cell line, MCAS cells were less proficient at cisplatin-DNA adduct repair than A2780/CP70 cells. In absolute terms, A2780/CP70 cells repaired 3-fold as much adduct (2.7 pg/microgram DNA over 6 h vs 0.86 pg/microgram DNA); and when expressed in terms of the maximal DNA adduct load, A2780/CP70 cells repaired 50% more adduct than MCAS cells. MCAS cells had increased cytosolic inactivation of drug at the IC50 dose level, which has been previously suggested to be a compensatory cellular response for reduced DNA repair capacity. These data suggest the possibility that this specific ERCC1 polymorphism, may be associated with reduced DNA repair capacity in human ovarian cancer cells. This association may be effected through a reduction in peak production of ERCC1 mRNA, and a consequent reduction in the translation of ERCC1 mRNA into protein.

[Wetland ecosystems formation and its protection in Yellow River Delta]

Site investigation, satellite photo analysis and historic material analysis show that the vast neonatal wetlands in Yellow River Delta were created by high concentration sediment of the river and the land-sea evolution. Affected by the regional climate, landform, geological deposition, soil, vegetation and their interactions, the wetlands covered 4.5 x 10(5) hm2, 6.84 x 10(4) hm2 of which were artificial wetlands. The wetland ecosystems changed with the waving of the Yellow River Mouth and the land development in the Delta area. From ocean to land, the sublittoral aquatic wetland, eulittoral wetland, eplittoral salt wetland, bulrush-quitch wetland, meadow wetland and land agroecosystem were developed. The wetland ecosystems had abundant biological resources, including 1524 wild animals, 300 birds and 1040 fishes, which were changed recently by the oil development and affected by the interruption of Yellow River. Wetland protection should be strengthened in resources utilization.

Cisplatin and phorbol ester independently induce ERCC-1 protein in human ovarian carcinoma cells

Nucleotide excision repair (NER) is the DNA repair pathway by which cisplatin-induced damage is removed from DNA in human cells. ERCC-1 is one of the essential proteins in NER, and is essential for life. Enhanced ERCC-1 expression has been associated with clinical and cellular resistance to cisplatin. We therefore carried out this study to investigate the effect of cisplatin on ERCC-1 protein expression in A2780/CP70 human ovarian cancer cells. Western blot analysis showed that ERCC-1 protein levels were increased to more than 3 times control after a 1 h cisplatin exposure to A2780/CP70 cells in culture. This increase was time- and concentration-dependent. The effect of cisplatin was maximal at 40 mM and peaked 24-48 h after exposure to the drug. These results extend our previous observations that ERCC-1 mRNA expression is induced by cisplatin in this system. TPA, a known AP-1 activator and tumor-promoting phorbol ester, also induced ERCC-1 protein to the same extent as cisplatin, but did not synergize with cisplatin in this regard. These findings suggest that ERCC-1 gene up-regulation in these cells can result through a DNA damage-response pathway, or through the induction of AP-1 activity, independent of the occurrence of DNA damage.

Alternative splicing of ERCC1 and cisplatin-DNA adduct repair in human tumor cell lines

Alternative splicing is a common natural tool for the inhibition of function of full length gene products. We explored whether there was evidence that alternative splicing of ERCC1 may serve such a function for nucleotide excision repair. The ratio of alternatively spliced species to full length species was assessed for the protein and/or for the mRNA, for a series of human cell lines and tissues. This ratio was plotted against the amount of cisplatin-DNA adduct repair in each cell line (n=9), as measured by atomic absorbance spectrometry. As the percentage of alternatively spliced protein and/or mRNA increased, the amount of cisplatin-DNA adduct that was repaired was reduced. This inverse relationship was associated with a substantial amount of scatter (r=0.635), particularly at low levels of repair. These data demonstrate an association between alternative splicing of ERCC1, and reduction in cellular capability to repair cisplatin-DNA adduct.

A nucleotide polymorphism in ERCC1 in human ovarian cancer cell lines and tumor tissues

We studied the DNA sequence of the entire coding region of ERCC1 gene, in five cell lines established from human ovarian cancer (A2780, A2780/CP70, MCAS, OVCAR-3, SK-OV-3), 29 human ovarian cancer tumor tissue specimens, one human T-lymphocyte cell line (H9), and non-malignant human ovary tissue (NHO). Samples were assayed by PCR-SSCP and DNA sequence analyses. A silent mutation at codon 118 (site for restriction endonuclease MaeII) in exon 4 of the gene was detected in MCAS, OVCAR-3 and SK-OV-3 cells, and NHO. This mutation was a C-->T transition, that codes for the same amino acid: asparagine. This transition converts a common codon usage (AAC) to an infrequent codon usage (AAT), whereas frequency of use is reduced two-fold. This base change was associated with a detectable band shift on SSCP analysis. For the 29 ovarian cancer specimens, the same base change was observed in 15 tumor samples and was associated with the same band shift in exon 4. Cells and tumor tissue specimens that did not contain the C-->T transition, did not show the band shift in exon 4. Our data suggest that this alteration at codon 118 within the ERCC1 gene, may exist in platinum-sensitive and platinum-resistant ovarian cancer tissues.