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 email@example.com
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.
Field surveys were conducted across the Blacklands region of Texas during 2016 and 2017 to document the distribution of herbicide-resistant Lolium spp. infesting winter wheat production fields in the region. A total of 68 populations (64 Italian ryegrass, four perennial ryegrass) were evaluated in a greenhouse for sensitivity to herbicides of three different modes of action: an acetolactate synthase (ALS) inhibitor (mesosulfuron-methyl), two acetyl-coenzyme-A carboxylase (ACCase) inhibitors (diclofop-methyl and pinoxaden), and a 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) inhibitor (glyphosate). Herbicides were applied at twice the label-recommended rates for mesosulfuron-methyl (29 g ai ha−1), diclofop-methyl (750 g ai ha−1), and pinoxaden (118 g ai ha−1); and at the recommended rate for glyphosate (868 g ae ha−1). The herbicide screenings were followed by dose-response assays of the most-resistant ryegrass population for each herbicide at eight rates (0.5, 1, 2, 4, 8, 16, 32, and 64×), compared with a susceptible population at six rates (0.0625, 0.125, 0.25, 0.5, 1, and 2×). The initial screening and dose-response experiments were conducted in a completely randomized design with three replications and two experimental runs. Survivors (<80% injury) were characterized as highly resistant (0% to 20% injury) or moderately resistant (21% to 79%). Results showed that 97%, 92%, 39%, and 3% of the Italian ryegrass populations had survivors to diclofop-methyl, mesosulfuron-methyl, pinoxaden, and glyphosate treatments, respectively. Of the four perennial ryegrass populations, three were resistant to diclofop-methyl and mesosulfuron-methyl, and one was resistant to pinoxaden as well. Perennial ryegrass populations did not exhibit any resistance to glyphosate. Dose-response assays revealed 37-, 196-, and 23-fold resistance in Italian ryegrass to mesosulfuron-methyl, diclofop-methyl, and pinoxaden, respectively, compared with a susceptible standard. One Italian ryegrass population exhibited three-way multiple resistance to ACCase-, ALS-, and EPSPS-inhibitors. The proliferation of multiple herbicide–resistant ryegrass is a challenge to sustainable wheat production in Texas Blacklands and warrants diversified management strategies.
Although hypofractionated radiotherapy has been standardised in early breast cancer, even in post-mastectomy no such consensus has been developed for locally advanced breast cancer (LABC), probably due to complex planning and field matching. This study is directed towards dosimetric evaluation and comparison of toxicity, response and disease-free survival (DFS) comparison between hypofractionation and conventional radiotherapy in post-mastectomy LABC.
In total, 222 female breast cancer patients were randomly assigned to be treated with either hypofractionated radiotherapy (n = 120) delivering 40 Gy in 15 fractions over 3 weeks or conventional radiotherapy (n = 102) with 50 Gy in 25 fractions over 5 weeks after modified radical mastectomy (MRM) along with neoadjuvant and/or adjuvant chemotherapy. All patients were planned with treatment planning software and assessed regularly during and after treatment.
Median follow-up period was 178 weeks in conventional arm (CRA) and 182 weeks in hypofractionation arm (HFA). There exists a dosimetric difference between the two arms of treatment, in spite of similar dose coverage [planning treatment volume (PTV) D90 92·04% in CRA versus 92·5% in HFA; p = 0·49], average dose in HFA is less than that of CRA (p < 0·001); so is the maximum clinical target volume (CTV) dose (p < 0·001). Similarly, average lung dose in HFA arm is significantly lower than CRA (9·9 versus 10·84; p = 0·06), but the V20Gy of lung and V30Gy of heart had no difference. The toxicity of radiation was comparable with similar mean time to produce toxicity [CRA: 7 W, HFA: 10 W; hazard ratio 0·64, 95% confidence interval (CI) = 0·28–1·45]. Three-year recurrence event was alike in two arms (CRA: 4·9%, HFA: 5·8%; p = 0·76). Mean DFS in CRA is 230 weeks and that of HFA is 235 weeks with hazard ratio 1·01 (95% CI = 0·32–3·19; p = 0·987).
Though biologically effective dose (BED) in hypofractionation is lesser than that of conventional fractionation, there are indistinguishable toxicity, locoregional recurrence, distant failure rate and DFS between the two modalities.
In insurance analytics, textual descriptions of claims are often discarded, because traditional empirical analyses require numeric descriptor variables. This paper demonstrates how textual data can be easily used in insurance analytics. Using the concept of word similarities, we illustrate how to extract variables from text and incorporate them into claims analyses using standard generalized linear model or generalized additive regression model. This procedure is applied to the Wisconsin Local Government Property Insurance Fund (LGPIF) data, in order to demonstrate how insurance claims management and risk mitigation procedures can be improved. We illustrate two applications. First, we show how the claims classification problem can be solved using textual information. Second, we analyze the relationship between risk metrics and the probability of large losses. We obtain good results for both applications, where short textual descriptions of insurance claims are used for the extraction of features.
Lomatogonium gaurgopalii sp. nov., a new species of Gentianaceae from Sikkim Himalaya, is described and illustrated. It can be distinguished from its morphologically closest relative, Lomatogonium cherukurianum S.K.Dey & D.Maity, mainly by its robust habit, longer internodes, much larger creamy yellow flower and much larger floral parts; the presence of many hairs in an inverted semilunar arrangement behind the filament bases; and its larger, narrowly ovoid to narrowly ellipsoid ovary. Lomatogonium gaurgopalii is also unique in having pollen grains with striate-reticulate exine ornamentation without perforations.
We report the growth of molybdenum trioxide (MoO3) nanoribbons (NRs) on epitaxial Ag and oriented Au nanostructures (NSs) using an ultra-high vacuum (UHV)-molecular beam epitaxy (MBE) technique at different substrate temperatures. An approximately 2 nm silver (Ag) film has been deposited at different growth temperatures (using UHV-MBE) on cleaned Si(100), Si(110), and Si(111) substrates. For faceted Au NSs, an approximately 50 nm Au film has been deposited (using high-vacuum thermal evaporation) on a Si(100) substrate with a native oxide layer at the interface and the sample was annealed in low vacuum (≈10−2) and at high temperature (≈975°C). Scanning electron microscopy measurements were performed to determine the morphology of MoO3/Ag and MoO3/Au composite films. From energy dispersive X-ray spectroscopy elemental mapping and line scans it is found that faceted Au NSs are more favorable for the growth of MoO3 NRs than epitaxial Ag microstructures.
The present work describes the removal of Direct Red 81, Methyl Orange, Methylene Blue and Crystal Violet from aqueous solution using halloysite nanotubes. The clay mineral was physicochemically characterized using various methods. The influences of pH, interaction time, initial dye concentration, adsorbent amount and temperature on adsorption were monitored and interpreted. Although previous work has shown that acidic pH conditions favour the adsorption of pollutants from aqueous systems by clay materials, in this study maximum removal was possible over a wide range of pH conditions (pH ≥2–12). Adsorption was very rapid, and equilibrium was attained within 30 min. For all four dyes studied, chemical reaction seemed significant in the rate-controlling step, and the pseudo-second-order chemical reaction kinetics provided the best correlation of the experimental data. Thermodynamically, the process was spontaneous, with Gibbs energy decreasing with increasing temperature. Halloysite would be suitable for removing dyes from aqueous solution. This was further tested by using the halloysite nanotubes for the removal of complex dyes from printing and ink industry effluents.
High-entropy composites (HECs) were subjected to severe straining by high-pressure torsion (HPT) to evaluate their influence on the evolution of microstructure and deformation behavior. Severe straining leads to a homogeneously strained microstructure and inhomogeneous micro-shear bands in these HECs. Nb addition in HECs varies the microstructure from single phase to eutectic, and the Vickers microhardness in HPT HECs increases to 7.45 GPa. Nb addition up to x = 0.80 in as-cast HECs improves the strength of these materials at the expense of its plasticity. Nevertheless, severe straining provides a better combination of strength and ductility without sacrificing its plasticity. Such improvement in properties is attributed to the evolved microstructural features, formation of “transformation-shear bands (T-SBs)” and “deformation-shear bands (D-SBs)” at severe straining. This assures the homogeneous deformation by shear banding and suggests that shear banding is the dominant deformation mechanism when the lamellar spacing becomes saturated upon severe straining.
Recently, double perovskite-based oxide materials have been proposed for thermoelectric (TE) applications due to their environment-friendly nature, high-temperature stability, better oxidation resistance, and lower processing cost compared to conventional chalcogenides and intermetallics. In this review article, we have comprehensively summarized our recent research studies on Sr2B′B″O6-based double perovskites for high-temperature TE power generation. We have shown that decoupling of phonon-glass and electron-crystal behavior is possible in oxides by reducing thermal conductivity due to induced dipolar glassy state as a result of relaxor ferroelectricity. We have also introduced metal-like electrical conductivity (∼105 S/m) in these ceramics that are inherently insulator in nature. Moreover, we have observed interesting behavior of temperature-driven p–n type conduction switching assisted colossal change in thermopower in some of these oxides, hitherto, obtained only in chalcogenides. The charge transport mechanism in these complex oxides has been analyzed by small polaron hopping conduction model in conjugation with defect chemistry.
A new species, Gentiana arunii D.Maity, S.K.Dey, J.Ghosh & Midday, from alpine pasture in Sikkim Himalaya is described and illustrated, and placed in Gentiana section Chondrophyllae Bunge. The new species is compared morphologically with two related taxa, Gentiana glabriuscula T.N.Ho and Gentiana pluviarum W.W.Sm. subsp. subtilis (Harry Sm.) T.N.Ho.
A new species of Kuepferia (Gentianaceae), K. pringlei D.Maity & Sentu K.Dey from north Sikkim, Eastern Himalaya, is described and illustrated. Details of habitat, phenology and conservation status are given, and it is compared to related species. This previously undescribed species is most similar to, but distinct from, Kuepferia leucantha (Harry Sm. ex T.N.Ho & S.W.Liu) Adr.Favre, known from Bhutan and China.
This chapter deals with the experimental methods related to the measurement of fracture toughness and determination of resistance curves. All tests are done as per certain standards. The standards are generally very exhaustive; they provide all relevant information that may be needed about a test. Useful information in brief about the different testing is presented in this chapter.
Measurement of Plane Strain Fracture Toughness KIC
KIC testing is mostly done as per ASTM E399-90 (Reapproved 1997) (2000) or its equivalent.
The standard specifies specimen geometry, procedure for preparation of specimen, testing machine requirements, the sensitivity of measurement devices, and testing fixtures, and gives guidelines for conducting tests and data collection, along with methods of calculation of toughness and reporting of the experimental data. For a rolled or forged material, there are three distinct directions of symmetry: longitudinal (L), transverse (T), and short transverse (S). The toughness of such a material will depend on the orientation of the crack and the direction of loading during testing. If the loading is in the longitudinal direction and the crack plane is in the short transverse direction, the specimen is identified as L–S specimen; if the loading is in the transverse direction and the crack plane is in the short transverse direction, the specimen is identified as T–S specimen. Thus there are six possible combinations: L–S, S–L, L–T, T–L, S–T, and T–S. Three such combinations are illustrated in Fig. 9.1.
The two most commonly used specimen geometries, compact tension (CT) and three point bend (TPB), are shown in Figs. 9.2 and 9.3, respectively. Arc-shaped specimens are also recommended to facilitate their preparation from pressure vessel stock. For a measured fracture toughness KIC data to be valid according to this standard, specimen thickness B and crack size a must be greater than where σY is the yield point of the material. In the absence of a distinct yield point, 0.2% proof stress can be employed. This calls for an initial estimation of the toughness of the material.
Fracture mechanics studies the development and spreading of cracks in materials. The study uses two techniques including analytical and experimental solid mechanics. The former is used to determine the driving force on a crack and the latter is used to measure material's resistance to fracture. The text begins with a detailed discussion of fundamental concepts including linear elastic fracture mechanics (LEFM), yielding fracture mechanics, mixed mode fracture and computational aspects of linear elastic fracture mechanics. It explains important topics including Griffith theory of brittle crack propagation and its Irwin and Orowan modification, calculation of theoretical cohesive strength of materials through an atomic model and analytical determination of crack tip stress field. This book covers MATLAB programs for calculating fatigue life under variable amplitude cyclic loading. The experimental measurements of fracture toughness parameters KIC, JIC and crack opening displacement (COD) are provided in the last chapter.
Fracture mechanics provides the basis for designing machine and structural components with materials containing defects such as crack, gives rational approach for assessing degree of safety or reliability of an in-service degraded machine component, and helps to calculate the life of a component with crack subjected to cyclically fluctuating load, corrosion, creep, or a combination of all these. A crack is a discontinuity, internal or external (Figs 1.1 and 1.2), in the material with zero tip radius. The development of the subject has been driven by the stringent safety requirements of the aerospace industry, nuclear power plants and other safety-critical applications. The advancement in the understanding of the subject coupled with developments in material science, experimental methods, and numerical techniques such as finite element, boundary element, and meshless methods, has facilitated optimum design and minimization of material usage for an application.
This book presents the gradual development in the fundamental understanding of the subject and in numerical methods that have facilitated its applications. Though the subject can be studied from the viewpoint of material science and mechanics, the focus here is on the latter.
Linear Elastic Fracture Mechanics
Development of the subject originated with the work of Griffith (1921), who propounded the condition of unstable extension of an existing crack in a brittle material within the framework of global energy balance or the First Law of Thermodynamics. The shortcomings of the approach were eliminated by Irwin (1948), who classified the three fundamental modes of crack extension and presented the condition of fracture in terms of a parameter associated with the stress–strain field in the close neighbourhood of the crack-tip. He also showed the link between the crack-tip field parameter, the stress intensity factor (SIF), and the energy release rate parameter introduced by Griffith. These parameters have proved useful in characterizing the fracture of brittle materials and have helped in practical design applications. Brittle materials fracture without showing any plastic deformation before the onset of crack extension or during crack propagation. This type of failure is distinguished by the fact that the fractured parts can be put together to get the original geometry almost reconstructed (Fig. 1.1).
Elastic Plastic or Yielding Fracture Mechanics
Most materials that are used in engineering constructions and machine building are metallic and show plastic deformation around the crack-tip prior to crack extension and during crack extension (Fig. 1.2).