Atomic Layer Deposition of Buffer Layers for the Growth of Vertically Aligned Carbon Nanotube Arrays

Vertically aligned carbon nanotube arrays (VACNTs) show a great potential for various applications, such as thermal interface materials (TIMs). Besides the thermally oxidized SiO₂, atomic layer deposition (ALD) was also used to synthesize oxide buffer layers before the deposition of the catalyst, such as Al₂O₃, TiO₂, and ZnO. The growth of VACNTs was found to be largely dependent on different oxide buffer layers, which generally prevented the diffusion of the catalyst into the substrate. Among them, the thickest and densest VACNTs could be achieved on Al₂O₃, and carbon nanotubes were mostly triple-walled. Besides, the deposition temperature was critical to the growth of VACNTs on Al₂O₃, and their growth rate obviously reduced above 650 °C, which might be related to the Ostwald ripening of the catalyst nanoparticles or subsurface diffusion of the catalyst. Furthermore, the VACNTs/graphene composite film was prepared as the thermal interface material. The VACNTs and graphene were proved to be the effective vertical and transverse heat transfer pathways in it, respectively.

High-Performance On-Chip Supercapacitors Based on Mesoporous Silicon Coated with Ultrathin Atomic Layer-Deposited In2O3 Films

On-chip supercapacitors have attracted considerable attention because of their high power density, long cycling life, and compatibility with integrated circuits. One critical drawback that restricts their practical application is the low energy density. In this work, low-resistivity mesoporous silicon with a high aspect ratio is prepared by Pt film-assisted chemical etching and utilized as the scaffold of the supercapacitors. Subsequently, low-resistivity (<0.0015 Ω·cm) and ultrathin In₂O₃ films are coated on the mesoporous silicon scaffold by atomic layer deposition at 200 °C, serving as the active electrode material. The electrochemical measurements reveal that the coating of the In₂O₃ film remarkably improves the performance of the supercapacitors compared with those without the In₂O₃ coating. The supercapacitors with a 4.5 nm In₂O₃ film coating exhibit a capacitance density of 1.36 mF/cm² at a scan rate of 10 mV/s as well as a better stability against the scan rate. In addition, it is found that the pristine mesoporous silicon walls are collapsed after 400 times of sweeping while those with the In₂O₃ film coating are still intact even after 2000 times of sweeping. Meanwhile, a high energy density is also achieved without sacrificing the power performance.

Systematic Study of the SiOx Film with Different Stoichiometry by Plasma-Enhanced Atomic Layer Deposition and Its Application in SiOx/SiO₂ Super-Lattice

Atomic scale control of the thickness of thin film makes atomic layer deposition highly advantageous in the preparation of high quality super-lattices. However, precisely controlling the film chemical stoichiometry is very challenging. In this study, we deposited SiO_x film with different stoichiometry by plasma enhanced atomic layer deposition. After reviewing various deposition parameters like temperature, precursor pulse time, and gas flow, the silicon dioxides of stoichiometric (SiO₂) and non-stoichiometric (SiO_1.8 and SiO_1.6) were successfully fabricated. X-ray photo-electron spectroscopy was first employed to analyze the element content and chemical bonding energy of these films. Then the morphology, structure, composition, and optical characteristics of SiO_x film were systematically studied through atomic force microscope, transmission electron microscopy, X-ray reflection, and spectroscopic ellipsometry. The experimental results indicate that both the mass density and refractive index of SiO_1.8 and SiO_1.6 are less than SiO₂ film. The energy band-gap is approved by spectroscopic ellipsometry data and X-ray photo-electron spectroscopy O 1s analysis. The results demonstrate that the energy band-gap decreases as the oxygen concentration decreases in SiO_x film. After we obtained the Si-rich silicon oxide film deposition, the SiO_1.6/SiO₂ super-lattices was fabricated and its photoluminescence (PL) property was characterized by PL spectra. The weak PL intensity gives us greater awareness that more research is needed in order to decrease the x of SiO_x film to a larger extent through further optimizing plasma-enhanced atomic layer deposition processes, and hence improve the photoluminescence properties of SiO_x/SiO₂ super-lattices.

Thermal dependence of feeding performance and resting metabolic expenditure in different altitudinal populations of toad-headed lizards

Inter-population variations in growth rate can result from independent or interactive effects of genetic and environmental factors, and be induced by some physiological differences as well. Toad-headed lizards (Phrynocephalus vlangalii) from a higher-elevation population were shown to have a higher growth rate than those from a lower-elevation population. The physiological basis of growth rate variation in this species is not well understood. Here, we investigated the feeding performance and resting metabolic rate (RMR) of lower- and higher-elevation individuals at different test ambient temperatures to evaluate the role of differences in energy intake, assimilation efficiency and metabolic expenditure on growth rate variations. Within the range of 25-35 °C, lizard RMR increased with increasing test ambient temperature, but food intake, apparent digestive coefficient (ADC, food energy minus faecal energy divided by food energy), and assimilation efficiency (AE, food energy minus faecal and urinary energy divided by food energy) were less thermally sensitive in both populations. Higher-elevation lizards tended to eat more food and have a lower RMR than lower-elevation ones, despite the lack of differences in ADC and AE. Our result showed that more energy intake and reduced maintenance cost may be associated with the higher growth rate of higher-elevation lizards. Accordingly, inter-population differences in energy acquisition and expenditure could act as potential sources for geographic variation in growth rate.

Measurements of Microstructural, Chemical, Optical, and Electrical Properties of Silicon-Oxygen-Nitrogen Films Prepared by Plasma-Enhanced Atomic Layer Deposition

In this study, silicon nitride (SiNx) thin films with different oxygen concentration (i.e., SiON film) were precisely deposited by plasma enhanced atomic layer deposition on Si (100) substrates. Thus, the effect of oxygen concentration on film properties is able to be comparatively studied and various valuable results are obtained. In detail, x-ray reflectivity, x-ray photoelectron spectroscopy, atomic force microscopy, and spectroscopic ellipsometry are used to systematically characterize the microstructural, optical, and electrical properties of SiON film. The experimental results indicate that the surface roughness increases from 0.13 to 0.2 nm as the oxygen concentration decreases. The refractive index of the SiON film reveals an increase from 1.55 to 1.86 with decreasing oxygen concentration. Accordingly, the band-gap energy of these films determined by oxygen 1s-peak analysis decreases from 6.2 to 4.8 eV. Moreover, the I-V tests demonstrate that the film exhibits lower leakage current and better insulation for higher oxygen concentration in film. These results indicate that oxygen affects microstructural, optical, and electrical properties of the prepared SiNx film.

Anticipatory parental effects in a subtropical lizard in response to experimental warming

Parental effects may produce adaptive or maladaptive plasticity that either facilitates persistence or increases the extinction risk of species and populations in a changing climate. However, empirical evidence of transgenerational adaptive plastic responses to climate change is still scarce. Here we conducted thermal manipulation experiments with a factorial design in a Chinese lacertid lizard (Takydromus septentrionalis) to identify the fitness consequences of parental effects in response to climate warming. Compared to present climate conditions, a simulated warming climate significantly advanced the timing of oviposition, depressed the immune capability of post-partum females, and decreased the hatching success of embryos, but did not affect female reproductive output (clutch size and egg mass). These results indicate that maternal warming negatively affects female health, and embryonic hatchability. More interestingly, we found that offspring from parents exposed to warming environments survived well under a simulated warming climate, but not under a present climate scenario. Accordingly, our study demonstrates anticipatory parental effects in response to a warming climate in an ectothermic vertebrate. However, the fitness consequences of this parental effect will depend on future climate change scenarios.

Thermal physiological performance of two freshwater turtles acclimated to different temperatures

The thermal physiological performance of invasive species may play a crucial role in determining their invasion success. In this study, we acclimated two cohorts of hatchlings of freshwater turtles (native Mauremys reevesii and invasive Trachemys scripta elegans) from low and high-latitude collection sites, respectively, to different thermal conditions (20 and 30 °C) for 4 weeks, and then compared their thermal tolerance and locomotor performance. T. scripta elegans hatchlings could swim faster (but righted themselves more slowly), and tolerate a higher temperature and wider temperature range than M. reevesii hatchlings. Similarly, T. scripta elegans hatchlings had a greater maximal performance (P_max) value for swimming speed (but a lower P_max value for righting time) than M. reevesii hatchlings. Temperature acclimation had a significant impact on the thermal tolerance and locomotor ability of turtles, but the acclimation effect did not differ between the two species. T. scripta elegans hatchlings seemed to have a greater thermal plasticity than M. reevesii hatchlings. High-latitude individuals showed a greater low-temperature tolerance, but lower locomotor ability (longer righting time) than low-latitude ones. However, the thermal plasticity did not differ between latitudinal cohorts. Our results indicated that T. scripta elegans performed better than M. reevesii, which might contribute to its range expansion and invasive success.

[The clinical significance of PRL-3,VEGF expression in sinonasalsquamous cell carcinoma]

Objective:To analyze the clinical significance of phosphatase of regenerating liver-3(PRL-3) and vascular endothelial growth factor(VEGF)expression in sinonasal squamous cell carcinomas.Method:We use immunohistochemical analysis and RT-PCR to detecte the expression of PRL-3 and VEGF protein in 62 cases of sinonasal squamous carcinoma tissues(SNSCC),30 cases of nasal polyps(NP),and 25 cases of normal nasal mucosa(NM).Result:①The expression of PRL-3 and VEGF in sinonasal squamous cell carcinoma tissues were statistically higher than in nasal polyps and normal nasal mucosa tissues (P<0.05).②The expression of PRL-3 and VEGF were not correlated with patient's age or gender(P>0.05).But the High expression of PRL-3 and VEGF in SNSCC was significantly related with advanced,lower tumor differentiation and lymph node metastasis(P<0.05).③The expression of PRL-3 and VEGF was positively correlated in sinonasal squamous cell carcinomas.Conclusion:The expression of PRL-3 and VEGF in SNSCC may involve in the regulation of tumor growth and differentiation.The expressing intensity may reflect the proliferation activity of sinonasal squamous cell carcinoma cell.PRL-3 and VEGF may promote the tumor metastasis in a synergistic manner.

Environmental causes of between-population difference in growth rate of a high-altitude lizard

Background

Ectothermic animals living in cold (high latitude or high elevation) regions are predicted to grow slower due to limited thermal opportunities for activity and food resources than those living in warm regions. However, the Qinghai toad-headed lizards (Phrynocephalus vlangalii) grow faster and reach a larger adult size at a high-elevation site than at a low-elevation site. In this study, we aimed to identify the genetic and environmental causes of this between-population difference in growth rate by conducting mark-recapture and common garden experiments on juvenile growth rate, and investigating the thermal environment, lizard body temperature, potential prey availability at the two elevation sites.

Results

Compared with low-elevation individuals, high-elevation juvenile lizards had higher growth rates in the field, but grew at similar rates in the laboratory. High-elevation lizards had higher active body temperatures than low-elevation lizards despite similar air temperatures in the period of field investigation. The high-elevation site had relatively more and larger preys than the low-elevation site.

Conclusions

Inter-population difference in growth rate of P. vlangalii may primarily result from developmental plasticity in response to the difference in environmental resources, rather than genetic differentiation. The higher growth rate of high-elevation lizards is likely associated with higher potential food availability and higher active body temperatures.

Modification of the Potential Landscape of Molecular Rotors on Au(111) by the Presence of an STM Tip

Molecular rotors on solid surfaces are fundamental components of molecular machines. No matter whether the rotation is activated by heat, electric field or light, it is determined by the intrinsic rotational potential landscape. Therefore, tuning the potential landscape is of great importance for future applications of controlled molecular rotors. Here, using scanning tunneling microscopy (STM), we demonstrate that both tip-molecule distance and sample bias can modify the rotational potential of molecular rotors. We achieve the potential energy difference variations of ∼0.3 meV/pm and ∼18 meV/V between two configurations of a molecular rotor, a tetra- tert-butyl nickel phthalocyanine molecule on Au(111) substrate. Further analysis indicates that the mechanism of modifying the rotational potential is a combination of the van der Waals interaction and the interaction between the molecular dipole and an electric field. This work provides insight into the methods used to modify the effective rotational potential energy of molecular rotors.

Maternal warming influences reproductive frequency, but not hatchling phenotypes in a multiple-clutched oviparous lizard

The understanding of life-history responses to increased temperature is helpful for evaluating the potential of species for tackling future climate change. Herein, adult southern grass lizards, Takydromus sexlineatus, were maintained under two thermal regimes simulating current thermal environment and a 4 °C warming scenario to determine the effects of experimental warming on female reproduction and offspring phenotypes. Experimental warming caused females to oviposit earlier and more frequently; however, it did not affect other reproductive traits, including clutch size, egg mass and clutch mass. Accelerated embryonic development and energy accumulation rate might have occurred in warmed females. Maternal warming appeared to increase early embryonic mortality, but did not shift hatchling size and locomotor performance. Embryos of oviparous lizards might be more vulnerable to climate change at early stages than at later stages. The impacts of climate change in oviparous lizards might be adverse in the longer term because of the shift in pre-ovipositional embryo viability, which possibly led to a decreased number of hatchlings.

[Effect of different course of omeprazole in the treatment of laryngopharyngeal reflux]

Objective:To compare the efficacy and safety of omeprazole in the treatment of laryngopharyngeal reflux. Method:One hundred and sixty patients with laryngopharyngeal reflux in our hospital from March 2015 to January 2017 (diagnosis treatment for 8 weeks) were selected and randomly divided into group A, B, C, D, with 40 cases in each group. Each group of patients were treated with omeprazole enteric-coated capsules (20mg, Bid) for 1, 2, 3 and 4 months, respectively. The reflux symptom index(RSI), reflux finding score(RFS) score, and 24h intraesophageal pH-metry , pepsin detection were compared between the four groups before treatment, at the end of treatment, at 1 month and 2 months after treatment. The efficacy and side effects were evaluated.Result:With the increase of treatment course, patient's RSI and RFS score, 24h pH-metry <4.0 percentage, pepsin positive rate decreased gradually, and there was a significant difference between before and after treatment. After treatment, there was a statistical significance in group B and group A, group C and group B. There was no significant difference between group D and group C. After the end of treatment and up to 2 months of follow-up, the RSI and RFS scores gradually increased and 24h Ph-metry <4.0 percentage, pepsin positive rate increased in group A and B,and those were not significantly different in group C and group D. With the increase of treatment duration, the effective rate of treatment increased, which was 67.5%, 80.0%, 90.0% and 95.0%, respectively. The difference was statistically significant, but the adverse effects did not increase (P>0.05).Conclusion:Omeprazole is safe and effective in the treatment of laryngopharyngeal reflux. The symptoms and signs of the patients are obviously improved during the 5 months of the course, and the condition is relatively stable and the recurrence rate is low.

[Anterior cervical discectomy and fusion to treat cervical spondylosis with sympathetic symptoms]

OBJECTIVE

To investigate the clinical effectiveness of polytheretherketone (PEEK) cages assisted anterior cervical discetomy and fusion (ACDF) to treat cervical spondylosis with sympathetic symptoms.

METHODS

Retrospective analysis was undertaken for 39 patients who were diagnosed as cervical spondylosis with sympathetic symptoms and underwent ACDF with PEEK cages. Radiographs obtained before surgery, after surgery, and at the final follow-up were assessed for quality of fusion. The following criteria were used for assessing radiographic success of fusion: (1) endplate obliterated with no lucent lines; (2) obliteration of disc space by bony trabeculae; (3) less than 2°of intervertebral motion or 2 mm of motion between the spinous processes at the operated segment on flexion-extension lateral radiographs. The sympathetic symptoms including vertigo, headache, tinnitus, nausea and vomiting, heart throb, hypomnesia and gastroenterological discomfort were scored by 20-point system preoperatively, 2 months postoperatively and at the final follow-up. The recovery rate and clinical satisfaction rate were also evaluated. Surgical complications were also assessed.

RESULTS

They were followed up for at least one year. The mean follow-up was 15.6 months. Radiographs of the cervical spine at the last follow-up revealed a solid fusion with no signs of a pseudoarthrosis in 36 cases. In two patients delayed union and bony fusion were achieved at the end of 9 and 11 months. Pseudoarthosis was found in 1 case but the patient had no symptoms. The score of sympathetic symptoms before surgery, 2 months after surgery and at the final follow-up were 8.4±1.0,2.2±0.3,and 2.4±0.3, respectively. There were 22 excellent cases, 15 good cases, 1 fair case and 1 bad case in terms of RR. Good to excellent results were attained in 95% of theses patients. The sympathetic symptoms improved in all the patients and the score was significantly improved after surgery. There was one patient who had cerebral spinal fluid leakage but he recovered one week after surgery. Two patients felt a mild swallowing discomfort, but it disappeared within one month after surgery. Subcutaneous hematoma occurred in one patient due to obstructed drainage. It was cleared two days after surgery.

CONCLUSION

Cervical spondylosis patients with sympathetic symptoms may be managed successfully with ACDF using PEEK cages. Successful clinical results regarding symptom improvement and general satisfaction with the surgical procedure depend not only on obtaining successful decompression and radiographic fusion but also on patient selection.

Atomic Layer Deposition of Nickel on ZnO Nanowire Arrays for High-Performance Supercapacitors

A novel hybrid core-shell structure of ZnO nanowires (NWs)/Ni as a pseudocapacitor electrode was successfully fabricated by atomic layer deposition of a nickel shell, and its capacitive performance was systemically investigated. Transmission electron microscopy and X-ray photoelectron spectroscopy results indicated that the NiO was formed at the interface between ZnO and Ni where the Ni was oxidized by ZnO during the ALD of the Ni layer. Electrochemical measurement results revealed that the Ti/ZnO NWs/Ni (1500 cycles) electrode with a 30 nm thick Ni-NiO shell layer had the best supercapacitor properties including ultrahigh specific capacitance (∼2440 F g^-1), good rate capability (80.5%) under high current charge-discharge conditions, and a relatively better cycling stability (86.7% of the initial value remained after 750 cycles at 10 A g^-1). These attractive capacitive behaviors are mainly attributed to the unique core-shell structure and the combined effect of ZnO NW arrays as short charge transfer pathways for ion diffusion and electron transfer as well as conductive Ni serving as channel for the fast electron transport to Ti substrate. This high-performance Ti/ZnO NWs/Ni hybrid structure is expected to be one of a promising electrodes for high-performance supercapacitor applications.

Water assisted atomic layer deposition of yttrium oxide using tris(N,N′-diisopropyl-2-dimethylamido-guanidinato) yttrium(iii): process development, film characterization and functional properties

We report a new atomic layer deposition (ALD) process for yttrium oxide (Y₂O₃) thin films using tris(N,N′-diisopropyl-2-dimethylamido-guanidinato) yttrium(iii) [Y(DPDMG)₃] which possesses an optimal reactivity towards water that enabled the growth of high quality thin films. Saturative behavior of the precursor and a constant growth rate of 1.1 Å per cycle confirm the characteristic self-limiting ALD growth in a temperature range from 175 °C to 250 °C. The polycrystalline films in the cubic phase are uniform and smooth with a root mean squared (RMS) roughness of 0.55 nm, while the O/Y ratio of 2.0 reveal oxygen rich layers with low carbon contaminations of around 2 at%. Optical properties determined via UV/Vis measurements revealed the direct optical band gap of 5.56 eV. The valuable intrinsic properties such as a high dielectric constant make Y₂O₃ a promising candidate in microelectronic applications. Thus the electrical characteristics of the ALD grown layers embedded in a metal insulator semiconductor (MIS) capacitor structure were determined which resulted in a dielectric permittivity of 11, low leakage current density (≈10⁻⁷ A cm⁻² at 2 MV cm⁻¹) and high electrical breakdown fields (4.0–7.5 MV cm⁻¹). These promising results demonstrate the potential of the new and simple Y₂O₃ ALD process for gate oxide applications.

A new water assisted atomic layer deposition (ALD) process was developed using the yttrium tris-guanidinate precursor which resulted in device quality thin films.

Band Offsets and Interfacial Properties of HfAlO Gate Dielectric Grown on InP by Atomic Layer Deposition

X-ray photoelectron spectroscopy and high-resolution transmission electron microscopy have been used to determine interfacial properties of HfO₂ and HfAlO gate dielectrics grown on InP by atomic layer deposition. An undesirable interfacial InP_xO_y layer is easily formed at the HfO₂/InP interface, which can severely degrade the electrical performance. However, an abrupt interface can be achieved when the growth of the HfAlO dielectric on InP starts with an ultrathin Al₂O₃ layer. The valence and conduction band offsets for HfAlO/InP heterojunctions have been determined to be 1.87 ± 0.1 and 2.83 ± 0.1 eV, respectively. These advantages make HfAlO a potential dielectric for InP MOSFETs.

Effects of Post Annealing Treatments on the Interfacial Chemical Properties and Band Alignment of AlN/Si Structure Prepared by Atomic Layer Deposition

The influences of annealing temperature in N₂ atmosphere on interfacial chemical properties and band alignment of AlN/Si structure deposited by atomic layer deposition have been investigated based on x-ray photoelectron spectroscopy and spectroscopic ellipsometry. It is found that more oxygen incorporated into AlN film with the increasing annealing temperature, resulting from a little residual H₂O in N₂ atmosphere reacting with AlN film during the annealing treatment. Accordingly, the Si-N bonding at the interface gradually transforms to Si-O bonding with the increasing temperature due to the diffusion of oxygen from AlN film to the Si substrate. Specially, the Si-O-Al bonding state can be detected in the 900 °C-annealed sample. Furthermore, it is determined that the band gap and valence band offset increase with increasing annealing temperature.

Optical Constants and Band Gap Evolution with Phase Transition in Sub-20-nm-Thick TiO2 Films Prepared by ALD

Titanium dioxide (TiO₂) ultrathin films with different thicknesses below 20 nm were grown by atomic layer deposition (ALD) on silicon substrates at 300 °C. Spectroscopic ellipsometry (SE) measurements were operated to investigate the effect of thickness on the optical properties of ultrathin films in the spectra range from 200 to 1000 nm with Forouhi-Bloomer (F-B) dispersion relation. It has been found that the refractive index and extinction coefficient of the investigated TiO₂ ultrathin film increase while the band gap of TiO₂ ultrathin film decreases monotonically with an increase in film thickness. Furthermore, with the purpose of studying the temperature dependence of optical properties of TiO₂ ultrathin film, the samples were annealed at temperature from 400 to 900 °C in N₂ atmosphere. The crystalline structure of deposited and annealed films was deduced by SE and supported by X-ray diffraction (XRD). It was revealed that the anatase TiO₂ film started to transform into rutile phase when the annealing temperature was up to 800 °C. In this paper, a constructive and effective method of monitoring the phase transition in ultrathin films by SE has been proposed when the phase transition is not so obvious analyzed by XRD.

Direct Growth of Al2O3 on Black Phosphorus by Plasma-Enhanced Atomic Layer Deposition

Growing high-quality and uniform dielectric on black phosphorus is challenging since it is easy to react with O₂ or H₂O in ambient. In this work, we have directly grown Al₂O₃ on BP using plasma-enhanced atomic layer deposition (PEALD). The surface roughness of BP with covered Al₂O₃ film can reduce significantly, which is due to the removal of oxidized bubble in BP surface by oxygen plasma. It was also found there is an interfacial layer of PO _x in between amorphous Al₂O₃ film and crystallized BP, which is verified by both X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) measurements. By increasing temperature, the PO _x can be converted into fully oxidized P₂O₅.

In Situ Analysis of Oxygen Vacancies and Band Alignment in HfO2/TiN Structure for CMOS Applications

The density of oxygen vacancies characterization in high-k/metal gate is significant for semiconductor device fabrication. In this work, a new approach was demonstrated to detect the density of oxygen vacancies by in situ x-ray photoelectron spectroscopy (XPS) and ultraviolet photoelectron spectroscopy (UPS) measurement. Moreover, the band alignment of the structure with optical band gap measured by spectroscopic ellipsometry (SE) and valence band offset by UPS were reported. The specific areal density of oxygen vacancies in high-k dielectric of HfO₂/TiN was obtained by fitting the experiment data to be 8.202 × 10¹⁰cm^- 2. This study would provide an effective approach to characterize the oxygen vacancies based defects which cause threshold voltage shifts and enormous gate leakage in modern MOSFET devices.

Low-Temperature One-Step Growth of AlON Thin Films with Homogenous Nitrogen-Doping Profile by Plasma-Enhanced Atomic Layer Deposition

The AlON film with homogeneous nitrogen-doping profile was grown by plasma-enhanced atomic layer deposition (PEALD) at low temperature. In this work, the precursors of the NH₃ and the O₂ were simultaneously introduced into the chamber during the PEALD growth at a relatively low temperature of 185 °C. It is found that the composition of the obtained film quickly changes from AlN to Al₂O₃ when a small amount of O₂ is added. Thus, the NH₃:O₂ ratio should be maintained at a relatively high level (>85%) for realizing the AlON growth. Benefited from the growth method, the nitrogen can be doped evenly in the entire film. Moreover, the AlON films exhibit a lower surface roughness than the AlN as well as the Al₂O₃ ones. The Al 2p and N 1s X-ray photoelectron spectra show that the AlON film is composed of Al-N, Al-O, and N-Al-O bonds. Moreover, a three-layer construction of the AlON film is proposed through the Si 2p spectra analysis and reconfirmed by the transmission electron microscopy characterization. At last, the electrical and optical tests indicate that the AlON films prepared in this work can be employed as the gate dielectric in transistor application as well as the antireflection layer in photovoltaic application.

[Polymethylmethacrylate augmentation of bone cement injectable cannulated pedicle screws was used to treat degenerative lumbar scoliosis with osteoporosis]

OBJECTIVE

To describe the application of polymethylmethacrylate (PMMA) augmentation of cement-injectable cannulated pedicle screws for the treatment of degenerative lumbar scoliosis with osteoporosis.

METHODS

Retrospective cohort study was used to compare cement injectable cannulated pedicle screws (CICPs) group with PMMA augmentation and control group with traditional method in the correction surgery for Lenke-silva level III and level IV degenerative scoliosis cases with osteoporosis. Both groups were followed up for 1 year. The clinical results were assessed by visual analog scale (VAS) of pain on lumbar and lower limbers, Oswestry disability index (ODI) score and EuroQol-5 dimensions (EQ-5D) score. The coronal major curve Cobb angel in coronal plane and thoracic kyphosis Cobb angle, lumbar lordosis Cobb angle and sagittal vertical axis (SVA) in sagittal plane were tested in whole long spine X ray. The fusion rates were evaluated by lumbar X ray and dynamic X ray.

RESULTS

In this study 34 cases were enrolled, 15 cases in CICPs group and 19 cases in control group. The general characteristics including age, gender, weight, height, BMI and BMD were without statistical difference between the two groups. There were (5.7±2.2)PMMA augmentation screws in CICPs group. The operation time, blood loss and blood transfusion were higher in CICPs group than in control group, but without statistical difference. Lumbar VAS, lower limbers VAS, ODI score and EQ-5D were all better in 1 month postoperation, 6 months postoperation and 1 year postoperation than in preoperation in both groups. lumbar VAS scores of CICPs group in 6 months postoperation (CICPs group 3.1±1.3 vs. control group 4.4±1.4, P<0.01) together with lumbar VAS scores (CICPs group 3.3±1.0 vs. control group 5.2±1.4, P<0.01), ODI scores (CICPs group 22.7±17.2 vs. control group 31.4±18.5, P<0.01) and EQ-5D in 1 year postoperation (CICPs group 2.9±2.0 vs. control group 3.5±2.5, P<0.01)were lower than those of control group. The coronal major curve Cobb angels were all lower in 1 month postoperation, 6 months postoperation and 1 year postoperation than in preoperation in both groups; thoracic kyphosis Cobb angle and lumbar lordosis Cobb angle were all higher in 1 month postoperation, 6 months postoperation and 1 year postoperation than in preoperation in both groups. The coronal major curve Cobb angel was lower in CICPs group than that in control group in 1 year postoperation (CICPs group 17.6°±6.9° vs. control group 21.2°±7.2°, P<0.01)and thoracic kyphosis Cobb angle was higher in CICPs group than that in control group in 6 months postoperation (CICPs group -33.5°±8.8 ° vs. control group -28.9°±8.3°, P<0.01) and 1 year postoperation (CICPs group -33.0°±8.1° vs. control group -26.3°±7.4°, P<0.01) together with lumbar lordosis Cobb angle were higher in CICPs group than that in control group in 1 year postoperation (CICPs group 26.4°±8.1° vs. control group 22.1°±7.3°, P<0.01).

CONCLUSION

Polymethylmethacrylate augmentation of bone cement-injectable cannulated pedicle screws for the treatment of degenerative lumbar scoliosis with osteoporosis was effective and safe, the short-term clinical result was good.

[Polymethylmethacrylate augmentation of bone cement-injectable cannulated pedicle screws for the treatment of degenerative lumbar diseases with osteoporosis]

OBJECTIVE

To describe the application of polymethylmethacrylate augmentation of bone cement-injectable cannulated pedicle screws for the treatment of degenerative lumbar diseases with osteoporosis.

METHODS

Observation group included 14 cases of degenerative lumbar diseases with osteoporosis received polymethylmethacrylate augmentation of bone cement-injectable cannulated pedicle screws from November 2014 to July 2015, control group included 12 cases of degenerative lumbar diseases with osteoporosis received polymethylmethacrylate augmentation with traditional pedicle screws.The operation time, blood loss, number of pedicle screws and number of augmented pedicle screws in the two groups were compared. The bone cement leakage and pulmonary bone cement embolism in the two groups were also compared. The fusion rate and pedicle screws loosening by lumbar X ray and dynamic X ray were evaluated. The clinical results were assessed by visual analog scale (VAS) of pain on lumbar and lower limbers, lumbar Japanese Orthopaedic Association scores (JOA), Prolo functional scores and Oswestry disability (ODI) scores.

RESULTS

Differences of operation time and blood loss in the two groups were not statistically significant. The average number of pedicle screws was 9.9±4.7 and the average number of augmented pedicle screws was 5.9±2.6 in observation group while the average number of pedicle screws was 7.1±2.8 and the average number of augmented pedicle screws was 3.0±1.9 in control group. The ratio of augmented pedicle screws was higher in observation group than in control group (0.69±0.30 vs.0.47±0.30,P<0.05). The bone cement leakage rate was lower in observation group than in control group (5/83 vs. 12/42, P<0.01). All the cases in observation group were without leakage to the interspinal canal while one case in control group suffered from bone cement leakage to the interspinal canal with augmentation of 3 pedicle screws. The follow up period was (10.6±2.3) months in observation group and (36.5±7.2) months in control group. In final follow up, no case with non-fusion or pedicle screws loosening was found in both groups. Lumbar VAS, lower limbers VAS, lumbar JOA scores, Prolo functional scores and ODI scores were all better than pre-operation (P<0.01).

CONCLUSION

Polymethylmethacrylate augmentation of bone cement-injectable cannulated pedicle screws for the treatment of degenerative lumbar diseases with osteoporosis was effective, with simple working processes and lower risk of bone cement leakage. The short-term clinical result was good.

Low-Cost and High-Productivity Three-Dimensional Nanocapacitors Based on Stand-Up ZnO Nanowires for Energy Storage

Highly powered electrostatic capacitors based on nanostructures with a high aspect ratio are becoming critical for advanced energy storage technology because of their high burst power and energy storage capability. We report the fabrication process and the electrical characteristics of high capacitance density capacitors with three-dimensional solid-state nanocapacitors based on a ZnO nanowire template. Stand-up ZnO nanowires are grown face down on p-type Si substrates coated with a ZnO seed layer using a hydrothermal method. Stacks of AlZnO/Al2O3/AlZnO are then deposited sequentially on the ZnO nanowires using atomic layer deposition. The fabricated capacitor has a high capacitance density up to 92 fF/μm(2) at 1 kHz (around ten times that of the planar capacitor without nanowires) and an extremely low leakage current density of 3.4 × 10(-8) A/cm(2) at 2 V for a 5-nm Al2O3 dielectric. Additionally, the charge-discharge characteristics of the capacitor were investigated, indicating that the resistance-capacitance time constants were 550 ns for both the charging and discharging processes and the time constant was not dependent on the voltage. This reflects good power characteristics of the fabricated capacitors. Therefore, the current work provides an exciting strategy to fabricate low-cost and easily processable, high capacitance density capacitors for energy storage.

The thickness-dependent band gap and defect features of ultrathin ZrO2 films studied by spectroscopic ellipsometry

The band gap and defect features of ultrathin ZrO2 films with varying thicknesses have been investigated by spectroscopic ellipsometry through the point-by-point data inversion method. The ε2-sprectra in the 3-6 eV range are extracted based on an optical model consisting of a Si substrate/effective ZrO2 film/air ambient structure where the effective ZrO2 film is a combination of interfacial layers and ZrO2. Evident widening of the band gap with a reducing size is observed when the effective ZrO2 films are below a critical thickness, somewhere between 8.80 nm and 17.13 nm. This is due to quantum-confinement and amorphous effects. Moreover, the sub-band-gap defects at interfacial layers and in bulk ZrO2 are identified and present strong thickness dependence as well. The interfacial defects at 3.26, 4.13, 4.43, and 4.77 eV mainly exist below the critical thickness and exhibit a significant suppression with increasing film thickness. The bulk defects at 4.15 eV and 4.46 eV dominate in ZrO2 films once they are over the critical thickness. The evolution of the band gap and defects is closely related to variance in the electronic structure of amorphous ZrO2. Our results may be helpful in understanding controversial problems concerning the size effect on ultrathin high-k oxide films and exploring the further miniaturization of electronic devices based on them.