Qian Chen

Bio: Qian Chen is an academic researcher from Patuxent Wildlife Research Center. The author has contributed to research in topics: Heat exchanger & Pressure drop. The author has an hindex of 1, co-authored 1 publications receiving 145 citations.

Spatial patterns of bee captures in North American bowl trapping surveys

Abstract: . 1. Bowl and pan traps are now commonly used to capture bees (Hymenoptera: Apiformes) for research and surveys. 2. Studies of how arrangement and spacing of bowl traps affect captures of bees are needed to increase the efficiency of this capture technique. 3. We present results from seven studies of bowl traps placed in trapping webs, grids, and transects in four North American ecoregions (Mid-Atlantic, Coastal California, Chihuahuan Desert, and Columbia Plateau). 4. Over 6000 specimens from 31 bee genera were captured and analysed across the studies. 5. Based on the results from trapping webs and distance tests, the per bowl capture rate of bees does not plateau until bowls are spaced 3–5 m apart. 6. Minor clumping of bee captures within transects was detected, with 26 of 56 transects having index of dispersion values that conform to a clumped distribution and 39 transects having positive Green’s index values, 13 with zero, and only four negative. However, degree of clumping was slight with an average value of only 0.06 (the index ranges from −1 to 1) with only five values >0.15. Similarly, runs tests were significant for only 5.9% of the transects. 7. Results indicate that (i) capture rates are unaffected by short distances between bowls within transects and (ii) that bowls and transects should be dispersed throughout a study site.

Performance evaluation of fin-and-tube heat exchangers in an outdoor unit considering air flow mal-distribution

Abstract: The heat transfer capacity of air conditioning outside units is inextricably related to fins and airflow distribution, and research on the combination of the two is lacking. To analyze the fins and fin-and-tube heat exchanger, three-dimensional numerical models of the fins and flow field of the outdoor unit are created in this paper. On the one hand, the heat transfer and fluid flow characteristics of the fins are quantitatively evaluated and analyzed. On the other hand, the resistance coefficients of the porous media are numerically fitted to study the uniformity of the air velocity distribution on the surface of the heat exchanger. Two indexes, the total integrated heat capacity and JF-factor, are applied to evaluate the performance of the fins and fin-and-tube heat exchanger on the overall and specific levels, respectively. The results indicate that slit fins perform better than wave fins at heat transfer, whereas plain fins perform the worst. However, improved heat transfer performance results in increased pressure drop, which has a two-sided effect. It causes both a decrease in air volume flow rate and an increase in air distribution uniformity. Comparing the comprehensive performance of different fins, JF-factors of slit fins and wave fins are on average 20.95% and 14.36% higher than plain fins. In terms of overall performance, slit fins and wave fins have higher integrated heat exchange capacities than plain fins by 18.0% and 9.33%, respectively.

Traditional uses, phytochemistry and pharmacology of Ficus carica: A review

Abstract: Context: Ficus carica Linn (Moraceae) has been used in traditional medicine for a wide range of ailments related to digestive, endocrine, reproductive, and respiratory systems. Additionally, it is also used in gastrointestinal tract and urinary tract infection.Objective: This review gathers the fragmented information available in the literature regarding morphology, ethnomedicinal applications, phytochemistry, pharmacology, and toxicology of Ficus carica. It also explores the therapeutic potential of Ficus carica in the field of ethnophytopharmacology.Materials and methods: All the available information on Ficus carica was compiled from electronic databases such as Academic Journals, Ethnobotany, Google Scholar, PubMed, Science Direct, Web of Science, and library search.Results: Worldwide ethnomedical uses of Ficus carica have been recorded which have been used traditionally for more than 40 types of disorders. Phytochemical research has led to the isolation of primary as well as secondary metabol...

Diverse landscapes have a higher abundance and species richness of spring wild bees by providing complementary floral resources over bees' foraging periods.

Abstract: Anthropogenic landscape simplification and natural habitat loss can negatively affect wild bees. Alternatively, anthropogenic land-use change may diversify landscapes, creating complementary habitats that maintain overall resource continuity and diversity. We examined the effects of landscape composition, including land-cover diversity and percent semi-natural habitat, on wild bee abundance and species richness within apples, a pollinator-dependent crop. We also explored whether different habitats within diverse landscapes can provide complementary floral resources for bees across space and time. We sampled bees during apple bloom over 2 years within 35 orchards varying in surrounding landscape diversity and percent woodland (the dominant semi-natural habitat) at 1 km radii. To assess habitat complementarity in resource diversity and temporal continuity, we sampled flowers and bees within four unique habitats, including orchards, woodlands, semi-natural grasslands, and annual croplands, over three periods from April–June. Surrounding landscape diversity positively affected both wild bee abundance and richness within orchards during bloom. Habitats in diverse landscapes had different flower communities with varying phenologies; flowers were most abundant within orchards and woodlands in mid-spring, but then declined over time, while flowers within grasslands marginally increased throughout spring. Furthermore, bee communities were significantly different between the closed-canopy habitats, orchards and woodlands, and the open habitats, grasslands and annual croplands. Our results suggest that diverse landscapes, such as ones with both open (grassland) and closed (woodland) semi-natural habitats, support spring wild bees by providing flowers throughout the entire foraging period and diverse niches to meet different species’ requirements.

Potential Bias in Pan Trapping as a Function of Floral Abundance

Abstract: Our study sites were located at the Marvin Klemme Research Range (MKRR) and the Stillwater Research Range (SRR). The MKRR is located approximately 15 km South of Clinton in west-central Oklahoma and is predominantly a mixed-grass prairie. We used the MKRR to evaluate pan trap effectiveness at sites with and without floral resource removal via herbicide applications. An aerial application combining 2,4D (2,4-Dichlorophenoxyacetic acid), picloram, and AllyH XP herbicide (0.7 kg acid equivalent/ha) was applied 15 May 2009. Herbicide applications reduced forb species richness by 63.6%, 100%, 88.9%, and 83.3% during June, July, August, and September, respectively, within the study plots. Forb abundance also was reduced by .95% each month in the herbicide treated plots. Four separate pastures (two treated with herbicide and two untreated controls) ranging in size from 40 to 50 ha were sampled at the MKRR, with two sampling areas located a minimum of 200 m apart in each pasture. The SRR is located approximately 21 km southwest of Stillwater in north-central Oklahoma and is predominantly a tallgrass prairie. We used the SRR to evaluate the effect of low and high floral resource availability generated by annual variations in precipitation on pan trap effectiveness. 2006 was a drought year with 30.5% less rainfall than normal based on the 30 year average from 1971–2000, whereas 2007 was a wet year with almost twice as much rainfall as normal (data obtained from a Mesonet station located on the SRR; http://www.mesonet.org/). Although no formal estimates of floral resource availability were recorded, flower resources were very limited in 2006 and abundant in 2007 (KAB, pers. obs.). Three separate pastures

Towards a standardized Rapid Ecosystem Function Assessment (REFA)

Abstract: Quantifying ecosystem functioning is important for both fundamental and applied ecological research. However, there is currently a gap between the data available and the data needed to address topical questions, such as the drivers of functioning in different ecosystems under global change or the best management to sustain provisioning of ecosystem functions and services. Here, we identify a set of important functions and propose a Rapid Ecosystem Function Assessment (REFA). The proposed methods were specifically selected to be low-tech, easy to use, repeatable, and cost efficient. Thus, REFA enables standardized and comparable measurements of proxies for these functions that can be used at a large scale within and across studies. Adopting REFA can help to close the identified ecosystem functioning data gap.

Wild bee abundance declines with urban warming, regardless of floral density

Abstract: As cities expand, conservation of beneficial insects is essential to maintaining robust urban ecosystem services such as pollination Urban warming alters insect physiology, fitness, and abundance, but the effect of urban warming on pollinator communities has not been investigated We sampled bees at 18 sites encompassing an urban warming mosaic within Raleigh, NC, USA We quantified habitat variables at all sites by measuring air temperature, percent impervious surface (on local and landscape scales), floral density, and floral diversity We tested the hypothesis that urban bee community structure depends on temperature We also conducted model selection to determine whether temperature was among the most important predictors of urban bee community structure Finally, we asked whether bee responses to temperature or impervious surface depended on bee functional traits Bee abundance declined by about 41% per °C urban warming, and temperature was among the best predictors of bee abundance and community composition Local impervious surface and floral density were also important predictors of bee abundance, although only large bees appeared to benefit from high floral density Bee species richness increased with floral density regardless of bee size, and bee responses to urban habitat variables were independent of other life-history traits Although we document benefits of high floral density, simply adding flowers to otherwise hot, impervious sites is unlikely to restore the entire urban pollinator community since floral resources benefit large bees more than small bees