Book chapters will be unavailable on Saturday 24th August between 8am-12pm BST. This is for essential maintenance which will provide improved performance going forwards. Please accept our apologies for any inconvenience caused.
To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Latrophilin (LPH) is known as an adhesion G-protein-coupled receptor which involved in multiple physiological processes in organisms. Previous studies showed that lph not only involved the susceptibility to anticholinesterase insecticides but also affected fecundity in Tribolium castaneum. However, its regulatory mechanisms in these biological processes are still not clear. Here, we identified two potential downstream carboxylesterase (cce) genes of Tclph, esterase4 and esterase6, and further characterized their interactions with Tclph. After treatment of T. castaneum larvae with carbofuran or dichlorvos insecticides, the transcript levels of Tcest4 and Tcest6 were significantly induced from 12 to 72 h. RNAi against Tcest4 or Tcest6 led to the higher mortality compared with the controls after the insecticides treatment, suggesting that these two genes play a vital role in detoxification of insecticides in T. castaneum. Furthermore, with insecticides exposure to Tclph knockdown beetles, the expression of Tcest4 was upregulated but Tcest6 was downregulated, indicating that beetles existed a compensatory response against the insecticides. Additionally, RNAi of Tcest6 resulted in 43% reductions in female egg laying and completely inhibited egg hatching, which showed the similar phenotype as that of Tclph knockdown. These results indicated that Tclph affected fecundity by positively regulating Tcest6 expression. Our findings will provide a new insight into the molecular mechanisms of Tclph involved in physiological functions in T. castaneum.
The Endangered snow leopard Panthera uncia is a flagship species of mountainous central Asia, and a conservation concern. China has the largest extent of potential snow leopard habitat and is thus crucial for snow leopard conservation. There are many challenges to snow leopard conservation in China, however, and there is still little information on the species for many geographical locations, including the Tianshan Mountains of Xinjiang province, which are important because they potentially connect snow leopard populations in Krygyzstan and Kazakhstan with those in Mongolia. We used camera traps in four areas across eastern, central and western Tianshan, with a total survey effort of 3,216 camera-trapping days. We confirmed the presence of snow leopards and an abundance of potential snow leopard prey, including the Siberian ibex Capra sibirica, in all areas. We found 2–3 individual adult snow leopards at each site, with relatively limited survey effort, and more study is needed to fully investigate the importance of the Tianshan Mountains for the species. Establishing more protected areas is essential for snow leopard conservation, and we have used data from this study to apply for protected area status for several areas.
A sample with a radiocarbon concentration estimated to be greater than 105 times Modern was inadvertently graphitized and measured in the Xi'an AMS system last year. Both the sample preparation lines and the ion source system were seriously contaminated and a series of cleaning procedures were carried out to remove the contamination from them. After repeated and careful cleaning as well as continuous flushing with dead CO2 gas, both systems have recovered from the contamination event. The machine background is back to 2.0 x 10–16 and the chemical blank is beyond 50 kyr.
The Queen's University of Belfast, Northern Ireland and University of Waikato, Hamilton, New Zealand radiocarbon laboratories have undertaken a series of high-precision measurements on decadal samples of dendrochronologically dated oak (Quercus patrea) and cedar (Libocedrus bidwillii) from Great Britain and New Zealand, respectively. The results show a real atmospheric offset of 3.4 ± 0.6% (27.2 ± 4.7 14C yr) between the two locations for the interval ad 1725 to ad 1885, with the Southern Hemisphere being depleted in l4C. This result is less than the value currently used to correct Southern Hemisphere calibrations, possibly indicating a gradient in Δ14C within the Southern Hemisphere.
Zinc oxide (ZnO) is a crystalline material with diverse morphology, large bandgap and high visible light transparency. All of these characteristics make ZnO a suitable material for applications in optical devices such as photovoltaic cells and photodiodes. Regarding photovoltaic applications, it is necessary to grow ZnO on a transparent conducting oxide (TCO) substrate. In this work, vertically aligned 1-dimensional ZnO have been synthesized on a TCO substrate through chemical vapor deposition (CVD). Although ZnO is capable of being synthesized at lower temperatures through the use of Zn powder precursor, oxidation of precursor remains a significant limiting factor to control dimensional characteristics of the synthesized product.
In our work we have developed a method by which ZnO is synthesized under lower temperatures through the prevention of precursor oxidation and control of Zn vapor fluid dynamics. Partial pressure of Zn vapor—a significant factor in the morphology and quality of product—is controlled and maintained during growth. The morphology and crystal structure of the synthesized ZnO is characterized by scanning electron microscopy (SEM) and x-ray diffraction (XRD). We also demonstrate the fabrication of dye-sensitized solar cell (DSSC) with synthesized 1-dimensional ZnO, as a photoelectrode, and compare the photovoltaic characteristics of two devices fabricated under same conditions, except for the photoelectrode utilized.
Based on large-signal theory, a one-dimensional theoretical model of a coaxial vircator is developed to give the microwave gain of the nonlinear beam–wave interaction, and the effect of injected current premodulation on the microwave gain is analysed theoretically. In addition, a coaxial vircator with improved dual-cavity modulation structure, which has the advantage of enhancing the effect of the modulation cavity on the injected electron beam by way of feedback microwaves, is presented. The simulation results are presented to test the validity of the proposed theory, and it can be seen that the system power efficiency can become further strengthened by adjusting the parameters of the microwave feedback channel until the feedback electric field is at the proper phase. Finally, through optimization, a structure capable of generating 7.05 GW average output power and 19.5 % power conversion efficiency at 2.95 GHz operating frequency is obtained.
We present a concept to increase efficiencies utilizing nonlinear elements integrated with our semiconductor nanowire networks. Demonstrated here is power generation with thermoelectric devices made of two nanowire networks, one silicon and one indium phosphide, grown on a mechanically flexible copper substrate. Electron microscopy was utilized to characterize structural integrity of the nanowire networks. Non-linear current-voltage characteristics were observed, which suggests a new platform to increase maximum electrical power generation for a given temperature gradient.
The high carrier concentrations typically reported for nanowire devices indicate that when Schottky barrier transport is present, it occurs in the thermionic field emission regime with a substantial but not exclusive tunneling component. Analysis by thermionic field emission is difficult due to its multivariate nature. In recent work, we developed a mathematical stability approach that greatly simplified the evaluation of the multivariate thermionic field emission parameters. This is a general method with potentially wide applicability, requiring only the effective mass m* and relative dielectric constant εr for a given semiconductor as inputs. In the present work, we investigate the influence of the materials properties effective mass m* and relative dielectric constant εr on stability for a range of real and simulated semiconductor nanowires. A further investigation of temperature sensitivity and regime trends is presented.
The need for higher energy density batteries has spawned recent renewed interest in alternatives to lithium ion batteries, including multivalent chemistries that theoretically can provide twice the volumetric capacity if two electrons can be transferred per intercalating ion. Initial investigations of these chemistries have been limited to date by the lack of understanding of the compatibility between intercalation electrode materials, electrolytes, and current collectors. This work describes the utilization of hybrid cells to evaluate multivalent cathodes, consisting of high surface area carbon anodes and multivalent nonaqueous electrolytes that are compatible with oxide intercalation electrodes. In particular, electrolyte and current collector compatibility was investigated, and it was found that the carbon and active material play an important role in determining the compatibility of PF6-based multivalent electrolytes with carbon-based current collectors. Through the exploration of electrolytes that are compatible with the cathode, new cell chemistries and configurations can be developed, including a magnesium-ion battery with two intercalation host electrodes, which may expand the known Mg-based systems beyond the present state of the art sulfide-based cathodes with organohalide-magnesium based electrolytes.
Formation of patterned metal and semiconductor (e.g. silicon) nanowires is achieved using anodic aluminum oxide (AAO) templates with porous structures of different heights resulting from an initial step difference made by etching the aluminum (Al) thin film with a photoresist developer prior to the anodization process. This approach allows for the growth of vertically aligned nanowire arrays on a metal substrate, instead of an oriented semiconductor substrate, using an electroplating or a chemical vapor deposition (CVD) process. The vertically aligned metal and semiconductor nanowires defined on a metal substrate could be applied to the realization of vertical 3D transistors, field emission devices, or nano-micro sensors for biological applications.
Silicon (Si) nanowires offer great potential for field ionization (FI) applications due to well-established Si microfabrication methods combined with favorable ionizing properties of Si. Band bending of semiconductors under applied electric fields increases the FI probability, which is not possible with metal-based counterparts. While it has been demonstrated that scaling down the active material geometry can increase the FI efficiency, maximum electric field at the tip of a single nanowire decreases by quenching effect of nearby nanowires. In this work, optimization of Si nanowire geometries for improved FI efficiencies is explored.
To conduct a meta-analysis to compare the short-term outcomes of robotic thyroidectomy and conventional open thyroidectomy for differentiated thyroid cancer.
Medline, Embase, Science Citation Index Expanded and the Cochrane Library databases were searched for relevant literature. The evaluated endpoints were intra-operative and post-operative outcomes.
Twelve eligible, non-randomised comparative studies involving 2513 patients were included, with 923 patients in the robotic thyroidectomy group and 1590 patients in the conventional open thyroidectomy group. Meta-analysis results revealed that robotic thyroidectomy was associated with significantly longer operative time and a lower number of retrieved central lymph nodes, as compared with conventional open thyroidectomy. No significant differences were found between robotic thyroidectomy and conventional open thyroidectomy in terms of post-operative outcomes.
Robotic thyroidectomy appears to be a feasible and safe surgical procedure for patients with differentiated thyroid cancer. However, more high-quality randomised clinical trials should be undertaken to confirm these findings.
Escherichia albertii is a newly emerging enteric pathogen that has been associated with gastroenteritis in humans. Recently, E. albertii has also been detected in healthy and sick birds, animals, chicken meat and water. In the present study, the prevalence and characteristics of the eae-positive, lactose non-fermenting E. albertii strains in retail raw meat in China were evaluated. Thirty isolates of such strains of E. albertii were identified from 446 (6·73%) samples, including duck intestines (21·43%, 6/28), duck meat (9·52%, 2/21), chicken intestines (8·99%, 17/189), chicken meat (5·66%, 3/53), mutton meat (4·55%, 1/22) and pork meat (2·44%, 1/41). None was isolated from 92 samples of raw beef meat. Strains were identified as E. albertii by phenotypic properties, diagnostic PCR, sequence analysis of the 16S rRNA gene, and housekeeping genes. Five intimin subtypes were harboured by these strains. All strains possessed the II/III/V subtype group of the cdtB gene, with two strains carrying another copy of the I/IV subtype group. Pulsed-field gel electrophoresis showed high genetic diversity of E. albertii in raw meats. Our findings indicate that E. albertii can contaminate various raw meats, posing a potential threat to public health.
We have investigated the transport properties of topological insulator based on single-crystal Bi0.83Sb0.17 nanowires. The single-crystal nanowire samples in the diameter range 200 nm – 1.1 μm were prepared by the high frequency liquid phase casting in a glass capillary using an improved Ulitovsky technique; they were cylindrical single-crystals with (1011) orientation along the wire axis. In this orientation, the wire axis makes an angle of 19.5o with the bisector axis C1 in the bisector-trigonal plane. Bi0.83Sb0.17 is a narrow gap semiconductor with energy gap at L point of Brillouin zone ΔE= 21 meV. In accordance with the measurements of the temperature dependence of the resistivity of the samples resistance increases with decreasing temperature, but at low temperatures decrease in the resistance is observed. This effect, decrease in the resistance, is a clear manifestation of the interesting properties of topological insulators - the presence on its surface of a highly conducting zone. The Arrhenius plot of resistance R in samples with diameter d=1.1 µm and d=200 nm indicates a thermal activation behavior with an activation gap ΔE= 21 and 35 meV, respectively, which proves the presence of the quantum size effect in these samples. We found that in the range of diameter 1100 nm - 200 nm when the diameter decreases the energy gap is growing as 1/d. We have investigated magnetoresistance of Bi0.83Sb0.17 nanowires at various magnetic field orientations. From the temperature dependences of Shubnikov de Haas oscillation amplitude for different orientation of magnetic field we have calculated the cyclotron mass mc and Dingle temperature TD for longitudinal and transverse (B||C3 and B||C2) directions of magnetic fields, which equal 1.96*10-2m0, 9.8 K, 8.5*10-3m0 , 9.4 K and 1.5*10-1m0 , 2.8 K respectively. The observed effects are discussed.