Increasing Shell Thickness Research Articles

Size-dependent optical response of complex CoFe@Ag & CoFe@Au core-shell nanospheres

Mie theory was used to investigate the optical characteristics at resonance wavelength of complex CoFe@Ag & CoFe@Au core-shell nanoparticles of systematically varied core-sizes between 5–25 nm and shell thickness 2–10 nm. The observed spectra are originating in the wavelength range between 385–398 nm & 518–530 nm with increasing core-sizes of fixed Ag & Au shell thickness. Also, absorption spectra are found in the range of 361–435 nm & 514–532 nm wavelengths with increasing shell thickness of fixed core-sizes. The optical properties of CoFe alloy nanoparticles coated with Ag or Au shell as a function of core size and shell thickness can be tuned and controlled in the visible region of the electromagnetic spectrum and have potential applications in medicine, imaging, and bio-sensing.

Effect of Pelargonidin on carrier recombination lifetime of CTS quantum dots

In the current work, we have prepared stacks of Copper tin sulphide (CTS)/Pelargonidin core/shell quantum dots on soda lime substrates by SILAR technique. Copper tin sulphide quantum dots were of tetragonal phase matching well with JCPDS 089-4714. The absorption coefficient of the core/shell quantum dots increased while the photoluminescence intensity decreased with increasing shell thickness. Decrease of charge carrier confinement energy due to leakage of wavefunction into the shell is the cause of fall in PL intensity. Three transitions were found in all the samples corresponding to 1Se-1Sh, 1Pe-1Ph and 1De-1Dh transitions using the non-interacting particle model. Charge carrier recombination lifetime of P state was found to be in the order of 100 ns, with lifetime increasing with shell thickness, probably due to the P state being the most occupied at room temperature and decrease of surface trap sites with increasing shell thickness. Owing to the high lifetime of CTS/Pelargonidin core/shell quantum dots, these can be used effectively in solar cells where recombination time is a deciding factor for efficiency and also in bioimaging of living cells and tissues.

Effect of Dietary Zinc Level on Egg Production Performance and Eggshell Quality Characteristics in Laying Duck Breeders in Furnished Cage System

In order to investigate the effect of dietary Zn levels on laying performance, eggshell quality, and eggshell microstructure in Muscovy duck breeders under furnished cages. Firstly, the effects of age (35 weeks vs 40 weeks) and rearing system (littered floor vs furnished cage) on eggshell quality of laying duck breeders were studied (Exp. 1). Then, a total of 324 30-week-old Muscovy duck breeders were allotted into 3 dietary Zn groups with 6 replicates (18 ducks per replicate), including 0 mg Zn/kg (control-Zn group, C-Zn), 40 mg Zn/kg (normal-Zn group, N-Zn), and 140 mg Zn/kg (high-Zn group, H-Zn). The experimental period for 6 weeks was divided into 3 periods of 30-32, 32-34, and 34-36 weeks of age (Exp. 2). In Exp. 1, duck breeder eggs in the furnished cage system had lower the average shell thickness than birds in the littered floor system at 40 weeks of age (P < 0.05), not at 35 weeks of age. In Exp. 2, N-Zn and H-Zn groups had greater egg weight, egg production, and egg to feed ratio of duck breeders than C-Zn group (P < 0.05). Additionally, H-Zn group had higher laying rate, qualified egg ratio, and Haugh unit as well as lower mammillary cone width than C-Zn group (P < 0.05), with no differences between C-Zn and N-Zn groups (P > 0.05). Diet supplemented with 140 mg Zn/kg increased shell thickness and palisade layer thickness of duck breeders at 36 weeks of age (P < 0.05), but not at 32 and 34 weeks of age. In conclusion, diets with 40 or 140 mg Zn/kg improved egg production performance and egg quality of laying duck breeders during 30-36 weeks of age in a furnished cage system. Dietary supplementation of 140 mg Zn/kg level increased the ultrastructural palisade layer thickness contributing to greater eggshell thickness of duck breeders at 36 weeks of age.

Mechanical behavior of core–shell nanostructures

Nanotexturing reduces the effective contact between surfaces in relative motion, which can result in a lower coefficient of friction. However, nanotextured surfaces lack structural integrity, resulting in permanent deformation even at moderate contact forces. Therefore, core–shell nanostructures (CSNs) have been developed to protect the structural integrity of nanotextured surfaces. These CSNs can withstand higher contact forces, might include some plastic deformation (dislocations), but during unloading there is no evidence of residual plastic deformation. Therefore, the CSN is deformation resistant. In the current study, molecular dynamics simulations are used to study the effect of core (aluminum) radius, shell (amorphous silicon) thickness, and the random atomic distribution in the amorphous shell, on mechanical properties of core–shell nanostructures. The results suggest that core radius does not have a significant influence on the initial plastic deformation of the CSN. The shell thickness should be chosen so that the core to shell ratio is less than two to have deformation resistant CSNs. Further we observe that with an increase in core radii or shell thickness, the ability of a CSN to fully recover decreases. These results will help in the design of deformation resistant surfaces for MEMS/NEMS applications.

Micromagnetic simulations of reversal magnetization in core ((Nd&lt;sub&gt;0.7&lt;/sub&gt;, Ce&lt;sub&gt;0.3&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt;Fe&lt;sub&gt;14&lt;/sub&gt;B)-shell (Nd&lt;sub&gt;2&lt;/sub&gt;Fe&lt;sub&gt;14&lt;/sub&gt;B) type

The effects of core size, shell thickness and shell distribution on the coercivity of single-grain core ((Nd&lt;sub&gt;0.7&lt;/sub&gt;,Ce&lt;sub&gt;0.3&lt;/sub&gt;)&lt;sub&gt;2&lt;/sub&gt;Fe&lt;sub&gt;14&lt;/sub&gt;B)-shell (Nd&lt;sub&gt;2&lt;/sub&gt;Fe&lt;sub&gt;14&lt;/sub&gt;B) magnets are studied by programming and modeling them through using the C++ language. All the micromagnetic simulations are carried out via object oriented micro magnetic framework (OOMMF). The results show that the coercivity decreases with the increase of core size when the shell thickness is constant. It is considered that for the grain, the increase in the size of the core leads the average magnetocrystalline anisotropy field to increase and the total demagnetization energy to increase, thereby contributing to the magnetization reversal occurring under a smaller external field. When the core size is unchanged, as the shell thickness increases gradually, the coercivity first increases and then decreases. The analysis of the position of the nucleation point shows that the reason why the coercivity increases in the early period is mainly that the nucleation point is located at the core-shell junction and belongs to the core. As the thickness of the shell increases, the exchange interaction effect between the magnetic moment of the shell and the one of the nucleation point is strengthened, so a larger external field is needed in the nucleation process. As for the decrease of the coercivity in the later period, the main reason is that the nucleation points are exactly the vertices of the shell (also the vertices of the grain), and the increase of the shell thickness conduces to increasing the total demagnetization energy, so the nucleation points can be formed under a smaller external magnetic field. With core size and shell volume kept unchanged, when the shell is distributed on the two easy-axis planes (i.e. the planes perpendicular to the easy axis) of the core, the coercivity of the magnet reaches a largest value. It is because that the nucleation points are located at the vertices of the shell (also the vertices of the grain), of which the magnetocrystalline anisotropy field is larger, and the demagnetization field is smaller. Via magnetocrystalline anisotropy field, the demagnetization energy, nucleation point, etc, the changes of coercivity in above cases can be explained.

The effects of compression speed and positions on some cracking characteristics and kernel extraction quality of hazelnuts cv. Sivri

Bu çalışmada farklı sıkıştırma hızları (0.5, 1.0, 1.5 ve 2 mm/s) ve yönlerinin (uzunluk, genişlik ve kalınlık), Sivri fındık çeşidinde bazı kırılma özellikleri (kırma kuvveti, kırma enerjisi ve özgül deformasyon) ile iç çıkma kalitesi üzerine etkileri belirlenmiştir. Ayrıca kabuk kalınlığı ve geometrik ortalama çap değerleriyle bu kırılma özellikleri ve iç çıkma kalitesi arasındaki ilişki incelenmiştir. Bu amaçla 16.40 mm’den büyük ve küçük olan iki grup kabuklu fındık örneği üniversal tekstür cihazıyla sıkıştırma testlerine tabi tutulmuştur. En düşük kırılma kuvveti (167 N) ve enerjisi (105 J) uzunluk yönünden kuvvet uygulanan ikinci grup fındıklarda bulunmuştur. İncelenen fındık örneklerinde geometrik ortalama çap ve kabuk kalınlıklarının, kabuk kırılma özelliklerini önemli şekilde etkilediği bulunmuştur. Kabuk kalınlığı ve geometrik ortalama çap arttıkça genellikle kabuk kırılma kuvveti ve kırılma enerjisi artmış, özgül deformasyon ise düşmüştür. Yükleme hızı arttıkça birinci grup meyvelerde kırılma için ihtiyaç duyulan kuvvet ve enerji artarken, ikinci grupta bu değişim kararlılık göstermemiştir. Tüm kombinasyonlarda kırılma hızı artıkça iç çıkma kalitesi bariz olarak azalmıştır. Geometrik ortalama çap ile iç çıkma kalitesi arasında herhangi bir ilişki saptanamamıştır. Sonuç olarak iki grup için ortalama değerler dikkate alındığında en düşük kırılma kuvveti (199.5 N) uzunluk yönünden yapılan testlerde elde edilirken, iç çıkma kalitesi bakımından en iyi sonucu (5.00) genişlik ekseninde kırılan fındıklar vermiştir. Sivri fındık çeşidi için incelenen hızlar dikkate alındığında kaliteli iç eldesi için 1 mm/s’nin üzerindeki kırma hızları önerilmemektedir.

Facile synthesis of α-Fe2O3/ZnO core-shell nanowires for enhanced H2S sensing

The α-Fe2O3/ZnO core-shell nanowires (NWs) on micro-electro-mechanical system structure were prepared for hydrogen sulfide (H2S) gas sensing. Core α-Fe2O3 NWs were prepared by thermal oxidation and the ZnO shell layer was coated by atomic layer deposition, respectively. The diameter of the obtained α-Fe2O3/ZnO core-shell NWs increases uniformly with the increase of ZnO shell thickness. When the operating temperature is 250 °C, the maximum response of the α-Fe2O3/ZnO core-shell NWs gas sensor to 5 ppm H2S is 5.98, which is about five times of pure α-Fe2O3 NWs gas sensor (∼1.1). Moreover, α-Fe2O3/ZnO core-shell NWs-based gas sensors showed good selectivity, response, and recovery properties to H2S. The improvement of gas response of core-shell NWs is due to the slender α-Fe2O3/ZnO core-shell NWs and the appropriate energy band structure between ZnO and α-Fe2O3. Thus, the proposed α-Fe2O3/ZnO core-shell NWs will be one of ideal sensitive materials for H2S high-performance sensor.

Synthesis and Optical Properties of Cubic Chalcopyrite/Hexagonal Wurtzite Core/Shell Copper Indium Sulfide Nanocrystals.

We report a synthetic method to produce heavy-metal-free heterophase core/shell CuInS2 nanocrystals, which comprise differently sized cores with a cubic chalcopyrite (CP) structure overgrown with hexagonal wurtzite (WZ) shells. For a given core size, CP/WZ core/shell CuInS2 nanocrystals experience shifts in both absorption and photoluminescence spectra toward the near-infrared with increasing shell thickness. Studies of the photoluminescence dynamics of these heterophase CuInS2 nanocrystals reveals behavior similar to that of the typical type II nanostructures constructed from different semiconductor materials of the same crystal structure. The interface between the CP core and the WZ shell has an important effect on the photoluminescence quantum yield.

Monitoring the growth dynamics of colloidal gold-silver core-shell nanoparticles using in situ second harmonic generation and extinction spectroscopy.

The growth dynamics of gold-silver core-shell (Au@Ag) nanoparticles are studied using in situ time-dependent second harmonic generation (SHG) and extinction spectroscopy to investigate the nanoparticle shell formation. The silver shell is grown by reduction of silver cations onto a 14 nm gold core using ascorbic acid in colloidal aqueous solution under varying reaction concentrations producing Au@Ag nanoparticles of final sizes ranging from 51 to 78 nm in diameter. The in situ extinction spectra show a rapid increase in intensity on the timescale of 5-6 s with blue shifting and narrowing of the plasmonic peak during the silver shell formation. The in situ SHG signals show an abrupt rise at early times of the reaction, followed by a time-dependent biexponential decrease, where the faster SHG lifetime corresponds to the timescale of the shell growth, and where the slower SHG lifetime is attributed to changes in the nanoparticle surface charge density. A large enhancement in the SHG signal at early stages of the reaction is caused by plasmonic hot spots due to the nanoparticle surface morphology, which becomes smoother as the reaction proceeds. The final extinction spectra are compared to finite-difference time-domain (FDTD) calculations, showing general agreement with experiment, where the plasmon peak red shifts and increases in spectral width as the silver shell thickness increases. These in situ SHG and extinction spectroscopy results, combined with FDTD calculations, help characterize the complicated processes involved in colloidal nanoparticle shell formation in real time for developing potential plasmon-enhanced nanomaterial applications.

Dependence of Energy Product to the Shell Thickness in FePt/Fe3O4 Core/Shell Nanoparticles

A new model is presented to calculate energy product variation for FePt/Fe3O4 core/shell in the terms of Fe3O4 shell thickness. The spins at the core/shell interface and some parts of the core volume have a random orientation due to the presence of chemical disorder created by the experimental procedures. The mentioned random effects based on the chemical disorder and intermixing of core and shell produces random interactions, which according to the presented model can behave similar to the spin glass system. Due to the existence of a competition between exchange and anisotropy energies, the coercivity field contain two parts: In the first part, the effects of exchange interactions will dominate the effects of anisotropy. As a result, this section will include low anisotropy and frustrated spins, which is coupled to neighbor particles due to the strong exchange interactions. In the second part, which is the volume part of matter, the anisotropy is higher; in this case, the spins are frozen and remain fixed so that the neighbor particles do not have much effect on them. Since the nanoscale particles have a significant value of surface to volume ratio, there will be a competition between these two parts. Energy product variations for FePt/Fe3O4 core/shell increases when coherent rotation is dominant in the core/shell system. By increasing shell thickness, coherent rotation of spins disappears and the magnetization rotation will not be uniform, which leads to a decrease in energy product. To increase the maximum product energy, we need to increase the value of coercivity which is achieved by increasing the core thickness. If we can increase the magnetocrystalline anisotropy constant of the core, then the coercivity and thus the maximum energy product will increase.

Roughness and amorphization impact on thermal conductivity of nanofilms and nanowires: Making atomistic modeling more realistic

In this work, the impact of roughness and amorphization on the effective thermal conductivity of silicon nanofilms and nanowires is studied with atomistic simulations. The discrepancy between simulations and experimental measurements shows that it is necessary to consider realistic roughness and amorphization to reach an agreement. We show that subnanometric roughness and specific correlation length can reduce thermal transport by a factor of two in both nanofilms and nanowires; in addition, this reduction is even more pronounced than the one related to the existence of native oxides or amorphous phases on nanostructure edges. Furthermore, an interfacial thermal resistance parallel to the heat flux is observed. This thermal resistance is increasing upon the increase of the amorphous shell thickness, reaching a maximum value for thickness of 6 nm. Our findings could improve the strategy to elaborate nanomaterials with enhanced thermoelectric efficiency by tuning thermal conductivity through the engineering of surfaces.

Brachiopod shell thickness links environment and evolution

AbstractWhile it is well established that the shapes and sizes of shells are strongly phylogenetically controlled, little is known about the phylogenetic constraints on shell thickness. Yet, shell thickness is likely to be sensitive to environmental fluctuations and has the potential to illuminate environmental perturbations through deep time. Here we systematically quantify the thickness of the anterior brachiopod shell which protects the filtration chamber and is thus considered functionally homologous across higher taxa of brachiopods. Our data come from 66 genera and 10 different orders and shows well‐defined upper and lower boundaries of anterior shell thickness. For Ordovician and Silurian brachiopods we find significant order‐level differences and a trend of increasing shell thickness with water depth. Modern (Cenozoic) brachiopods, by comparison, fall into the lower half of observed shell thicknesses. Among Ordovician–Silurian brachiopods, older stocks commonly have thicker shells, and thick‐shelled taxa contributed more prominently to the Great Ordovician Biodiversification but suffered more severely during the Late Ordovician Mass Extinction. Our data highlight a significant reduction in maximum and minimum shell thickness following the Late Ordovician mass extinction. This points towards stronger selection pressure for energy‐efficient shell secretion during times of crisis.

On the formation of core-shell granules in batch high shear granulators at two scales

High shear granulation of powders with a wide size distribution can lead to the formation of core-shell particles consisting of a few larger particles in the core with a shell of fine particles. We demonstrate successful scale down of core-shell granule formation and, using a new model for interpreting observed cross-sections, show that above a critical speed the shell-thickness remains constant at about ~5% of the granule diameter with a crushing strength of about 5.5 MPa. Below this speed and at low fill-levels, shell-thickness increases and granule strength reduces. Under a low mixing intensity at the lowest fill-levels core-shell particles are not formed at all.Theoretical work on the strength of liquid bridges shows that small particles attached to each other would redistribute more easily than the same particles attached to a large particle. We propose therefore that a detachment-reattachment process is responsible for the formation of core-shell granules.

Facile and Affordable Process to Control Shell Thickness of Polydopamine-Assisted Polystyrene/Silver Core-Shell Particles

We prepared polystyrene (PS)/silver (Ag) core-shell particles with an excellent electrical conductivity in a facile, affordable and eco-friendly way. As core particles, monodisperse PS particles were synthesized by the process of dispersion polymerization. Then, the PS particles were coated with polydopamine (PDA) through the spontaneous oxidative polymerization of dopamine to produce PDA-coated PS particles. In essence, it is noted that the catechol and amine groups of PDA coated on PS particles can weakly reduce metallic ions. As a secondary reducing agent with an affordable price, glucose was therefore added to promote the reduction of metallic ions. Herein, the effect of glucose concentration on the Ag shell thickness of PDA-assisted PS/Ag core-shell particles was investigated. The degree of Ag reduction increased with an increase characteristically in glucose concentration, resulting in the increase of Ag shell thickness. Notably, a thick and uniform Ag shell layer could be plated on PDA-coated PS particles, which were noted to have rendered excellent electrical conductivity. When the glucose concentration of 55 mM was applied, the electrical conductivity of the PS/Ag core-shell particles reached as high as 7.8×105 S/m, which was almost close to that of conductive metals.

Fractal evolution of dual pH- and temperature-responsive P(NIPAM-co-AA)@BMMs with bimodal mesoporous silica core and coated-copolymer shell during drug delivery procedure via SAXS characterization

The dual (pH- and temperature-) responsive core-shell structured mesoporous nanomaterial P@BMMs were prepared using bimodal mesoporous silica as a core and poly(N-isopropylacrylamide-co-acrylic acid) P(NIPAM-co-AA) copolymer as a shell. Ibuprofen (IBU) was used as a model drug, and the effects of copolymer-coated shell thickness on drug loading and controlled release behavior were investigated by means of N2 sorption isotherms, dynamic light scattering measurements, X-ray diffraction patterns, Fourier transform infrared spectra, scanning electron and transmission electron microscopy, thermogravimetric profiles, and elemental analysis techniques. Particularly, their fractal evolutions in the drug delivery durations were explored via small angle X-ray scattering methods, demonstrating that the resultant P@BMMs before IBU-loading and after releasing possess the typical fractal features with spherical morphology. Meanwhile, the estimation for shell thickness of P@BMMs coating in different time intervals indicated that the drug-loaded capacity was improved with the increasing shell thickness, but drug-released rate varies, strongly depending on both shell thickness and release conditions. The drug delivery mechanism was preliminarily explored, following the Korsmeyer-Peppas model. Finally, cytotoxicity in cell and pharmacokinetic of released-IBU from hybrid nanocomposite in mice via intravenously injection were preliminarily explored.

Plasmon-enhanced photocatalytic activity of Pt@Au and Pt@Cu nanoparticles in quantum size regime

We have synthesized Pt@Au and Pt@Cu bimetallic nanoparticles and investigated their surface plasmon resonance (SPR) and plasmon-enhanced photocatalytic activity in the quantum size regime. The SPR wavelength of Pt@Au bimetallic nanoparticles monotonously blue-shifts as the thickness of Pt shell increases comparing with the quantum-sized Au core nanoparticles with diameter dAu = 3.6 ± 0.4 nm. On the other hand, the SPR of Pt@Cu bimetallic nanoparticles blue-shifts at first and then red-shifts as the Pt shell thickness increases comparing to the quantum-sized Cu core nanoparticles with diameter dCu = 3.7 ± 0.5 nm. Then, we comparatively investigated the photocatalytic activities of the Pt@Au nanoparticles with quantum and classical sizes. The photocatalytic rate for 4-NP:NaBH4 is enhanced 2 times by the strong plasmon resonance and the large surface area/volume ratio of quantum-sized Pt@Au nanoparticles. Additionally, the increasing photocatalytic activity of the quantum-sized Pt@Cu with the increase of Pt shell thickness is also observed. These findings reveal the significance of the quantum plasmon resonance on the enhancement of photocatalytic activity.

Cross-Linked Polystyrene Shells Grown on Iron Oxide Nanoparticles via Surface-Grafted AGET-ATRP in Microemulsion.

Most applications of nanoparticles require robust stabilization, for example, by surface-bound ligands or the encapsulation within polymer shells. Furthermore, for biomedical applications, the particles must be dispersible in a complex biological environment. Thus, high-quality nanoparticles synthesized in organic solvents must be transferred into aqueous media. Here, we present a novel scalable method enabling the robust hydrophilic encapsulation of non-agglomerated nanoparticles by growing polystyrene shells via AGET-ATRP in microemulsion. To demonstrate this approach, we encapsulate iron oxide nanoparticles (diameter: 13.7 ± 0.6 nm). Because the ATRP initiator is grafted onto the nanoparticles' surface, the shells are covalently attached to the iron oxide cores. By varying the amount of monomers, the shell thickness can be adjusted precisely, as indicated by the increasing hydrodynamic size from ∼22 to 26 nm (DLS, number mean) with an increasing amount of added monomers. Moreover, the degree of cross-linking can be controlled by the amount of added divinylbenzene (DVB). To evaluate the robustness of the polymer shells against ion infusion, we introduce a novel colorimetric method, which is based on the formation of the red iron thiocyanate complex. After addition of HCl, the increase in absorbance at 468 nm indicates leaching of iron ions from the polymer-encapsulated core particles. These measurements confirm that with increasing shell thickness, significantly improved shielding is achieved. Furthermore, high concentrations of added DVB [33-50% (v/v) in a monomer mixture] improve the shielding effect. However, when smaller amounts of DVB were added [10-25% (v/v)], the shielding effect was diminished, even in comparison to non-cross-linked polymer shells. This finding suggests a higher porosity of shells with a low degree of cross-linking.

Core-Shell Cadmium Telluride Quantum Platelets with Absorptions Spanning the Visible Spectrum.

CdS and CdSe shells are deposited on wurtzite CdTe quantum platelets (nanoplatelets) by exchanging the initial primary-amine ligation to Cd(OAc)2 ligation, with subsequent reaction of the Cd(OAc)2 ligand shell and thiourea or selenourea, respectively. Shell deposition is conducted in a cyclic manner, with 0.21-0.34 monolayers of CdS and 0.99-1.20 monolayers of CdSe being deposited in each cycle. The CdTe quantum platelets having an initial thickness of 1.9 nm are converted to CdTe-CdS and CdTe-CdSe core-shell quantum platelets having maximum thicknesses of 3.0 and 6.3 nm, respectively. The morphologies and wurtzite structure of the initial CdTe quantum platelets are retained upon shell deposition. The absorption spectrum of the CdTe quantum platelets is progressively shifted to lower energy with increasing shell thickness, across the entire visible spectrum. The spectral shifts observed scale with the inverse square of the total core-shell thickness.

Laying performance, immune response and antioxidant properties of hens segregating for naked neck and frizzle genes under low ambient temperature

Major genes could be introgressed into laying hens to attenuate heat stress. However, under cold and/or moderate ambient temperature, these genes might possess different behaviour. The main objective of this study was to evaluate laying performance, immune response, and antioxidant status of native laying hens segregating for naked neck (Na) and frizzle (F) genes under low ambient temperature. Five genotypes were studied: homozygous naked neck (NaNaff), heterozygous naked neck (Nanaff), homozygous frizzle (nanaFF), heterozygous frizzle (nanaFf), and normally feathered (nanaff). The hens were raised under temperature range 22.2–16.7°C. No adverse effect due to ambient temperature was detected in laying performance for naked neck genotypes. Significant decrease in egg weight was recorded in nanaFF genotype compared to the other genotypes leading to significant decrease in egg mass. Significant improvement in shell thickness was associated with Na and F genes. NaNaff genotype had a significantly higher eggshell strength compared to nanaff. Furthermore, Na and F genes improved cellular mediated immune responsiveness, whereas this improvement did not extend to humoral immunity. Birds carrying F gene in homozygous state had a higher total antioxidant activity compared to the remaining genotypes. It could be concluded that the presence of Na and F genes in laying hens raised under low ambient temperature significantly increased shell thickness and, in turn, improved shell strength. Moreover, they greatly enhanced cellular immunity, particularly in heterozygous naked neck status.

Chiroptical Activity of Type II Core/Shell Cu2S/CdSe Nanocrystals.

Ligand-induced chirality in core/shell nanocrystals (NCs) has attracted extensive attention because of many valuable potential applications. However, the cause of chirality especially in semiconductor nanomaterials is still under debate despite the creation of chiral type I core/shell structures. Herein, we synthesized a kind of new Cu2S/CdSe core/shell nanostructure to study the underlying reason. Four samples of Cu2S/CdSe were synthesized utilizing successive ion layer adsorption and reaction to vary the thickness of the CdSe shell upon a Cu2S core with 5 nm diameter. The chirality of type II Cu2S/CdSe NCs is imparted by l-/d-cysteine and penicillamine, which could be modulated with an increasing thickness of the CdSe shell. To the best of our knowledge, this is the first report of chiral type II core/shell semiconductor NCs. The hybridization theory can explain the variation trend of g factors with every increase in shell thickness from four monolayers (4 ML) to 7 ML. The results indicate that the chiroptical activity of semiconductor NCs is mainly due to hybridization between the holes in the valence band of NCs and the highest occupied molecular orbitals of the chiral ligands. In addition, Cu2S/CdSe NCs show a better chiroptical intensity in comparison with the type I structure according to previous work. The first design of chiral type II Cu2S/CdSe core/shell NCs and a detailed investigation of chiral variation trend help to give a better understanding of the chiral interaction between ligands and core/shell semiconductor nanostructures.