We report a novel technique for synthesizing hierarchical mesoporous non-oxide SiC ceramic from a block copolymer precursor. The block copolymers self-assemble into nano-scaled micelles with a core shell structure in toluene and the subsequent pyrolysis converts the aggregation of the micelles into SiC. The resultant SiC shows hierarchical mesoporous structure and has potential applications in catalysis, solar cells, separation, and purification processes. The technique is likely applicable in other non oxide material systems. (C) 2016 Published by Elsevier B.V.

The piezoresistive behavior of polymer-derived amorphous SiAlCO ceramic is studied in a temperature range of 25–300 °C. It is shown that the material exhibits a giant gage factor of 7000–16,000, much higher than that for any reported high-temperature materials. The result also reveals that the material exhibits a positive temperature-dependent piezoresistive stress coefficient within the temperature range. The unusual piezoresistivity of the material was attributed to the structure of the SiAlCO, which consists of highly disordered graphene-like carbon nanoclusters dispersed within an amorphous matrix comprising of SiC x O4−x tetrahedra. The huge piezoresistivity, together with the processibility and low-cost, make the material very promising for high-temperature sensor applications.

Wireless passive temperature sensors for harsh-environment applications based on cylindrical microwave cavity resonators are presented herein. Slot antennas are integrated with sensors with zero additional volume. The resonant frequencies of the sensors are determined by the dielectric constants of the ceramic materials, which monotonically increase versus temperature. Silicoboron carbonitride (SiBCN) ceramic materials, which are very robust inside harsh environments featuring high temperatures and corrosive gases, are optimized in this paper to reduce dielectric losses and increase sensing ranges and accuracies. A robust interrogation antenna is developed to wirelessly measure the sensors up to 1300 °C. Two sensors based on Si6B1 and Si4B1 ceramics are measured up to 1050 °C and 1300 °C, respectively, with a sensitivity of ~0.78 MHz/°C at 1050 °C. This type of wireless, passive, and robust sensor can be used for many harsh-environment applications, such as gas turbines.

Several important structural changes and their energetics during high-temperature annealing of polysilazane-derived amorphous silicon carbonitride ceramics were quantitatively studied. A 29Si solid-state NMR study indicated that the structural transition in the Si-containing area can be described by an equilibrium reaction, 4SiCN3=SiC4+3SiN4. The enthalpy and entropy for the reaction were calculated to be positive. Raman and electron paramagnetic resonance (EPR) studies revealed that the structural evolution within the free carbon area includes the graphitization of amorphous carbon and the lateral growth of nanographite, accompanied by a decrease in the point defect concentration. EPR results also suggested that the materials contain two kinds of point defects: carbon-dangling bonds at the edge and in the interior of the nanographite. It was found that the lateral growth of the nanographite followed a 2-D grain growth process, and that the decrease in the defect concentration was mainly due to the growth of the nanographite. The energetics of the structural changes was rationalized according to a simple structural model, and the effects of these changes on the stability of the materials were discussed.

The electric conductivity of polymer-derived SiBCNs pyrolyzed at different temperatures was studied. We showed that the boron impeded the graphitization of the free-carbon phase in the SiBCN, leading to a higher characteristic temperature and activation energy as compared to the SiCN. Such an impeding effect is due to the interaction between h-BN and graphite phase. We also provided a credible evidence to show that the increase in the electric conductivity of the SiBCN with pyrolysis temperature is likely due to the increase in the conductivity of the free-carbon phase.

Nonoxide SiCN hollow nanospheres were prepared from a block‐copolymer comprising of a precursor block and a sacrificial block. The copolymer was first synthesized and then self‐assembled into core‐shell structured micelles with the sacrificial block forming the core and the precursor block forming the shell. The micelles were subsequently pyrolyzed at high temperatures to transform the shell into ceramics and to completely decompose the core to form a hole. The technique is probably applicable to other material systems.

Study of site-specific N-glycosylation in complex sample remains a huge analytical challenge because protein glycosylation is structurally diverse in post-translational modifications, resulting in an intricacy of N-glycopeptides. Here we have developed a novel approach for high-throughput N-glycopeptide profiling based on a network-centric algorithm for deciphering glycan fragmentation in mass spectrometry. We performed an extensive validation and a high-throughput N-glycosylation study on serum and identified thousands of N-glycopeptide spectra with high confidence. The results revealed a similar level of glycan microheterogeneity to that of conventional glycomics approach on individual proteins and provided the unique in-depth site-specific information that could only be studied through glycopeptide profiling.

This is a prospective clinical study to compare the scattered fetal dose during Accelerated Partial Breast Irradiation (APBI) versus External Beam Radiation Therapy (EBRT). The scattered dose to the lower anterior abdominal wall of 14 consecutive patients treated with Accelerated Partial Breast Brachytherapy (APBI) were recorded using film badges. The film badges were placed on the anterior abdominal wall midway between the umbilicus and symphysis pubis. This is comparative to a 16 week pregnancy. None of the treated women were pregnant. APBI used SAVI devices of different sizes. The dose per treatment was 340 cGy prescribed to one cm around the lumpectomy cavity. One cm bolus was added on top of the film badges. No shielding was attempted for the first 4 cases. For the following 10 cases a lead apron was applied on top of the abdomen and pelvis. The scattered dose was also measured using the same way for another 10 patients treated with external beam radiation using 3D/IMRT to the whole breast. The dose prescribed was 180 cGy per fraction. No abdominal shielding was attempted. The doses were recorded for only five treatments and multiplied by 5 to account for a total dose of 45 Gy. The measured doses for 14 patients treated with APBI (4 without shielding and 10 with lead apron) were analyzed and compared to the doses collected for 10 patients treated with EBRT). Our data showed that APBI patients received much lower doses as compared to patients treated with EBRT. Adding a lead apron had decreased the exposure dose by more than 50% (p = 0.01). The average dose for APBI patients was 9.2 cGy (without shielding) and 4.4 cGy (with shielding) as compared to 15.5 cGy for patients treated with EBRT. The recorded doses were closely related to the distance between the SAVI device and the film badges, (p = 0.05). Also, there was close correlation between the patient weight and the recorded doses (p = 0.05) with heavier patients having lower doses. APBI contributes less scattered dose to the fetus as compared to whole breast radiation. The scattered dose is much easier to block due to the lower energy used. The longer the distance between the SAVI and the pelvis, and the heavier the weight of the patient, the less the dose recorded.

A long-existing problem that the conductivity of amorphous silicon carbonitrides derived from polymeric precursor increases significantly with pyrolysis temperature is investigated. We show that the conductivity exhibited an Arrhenius dependence on pyrolysis temperature, with the activation energy of ∼3.41 eV. Structural analysis using Raman spectroscopy reveals that the free carbon within the material undergoes a sp3-to-sp2 transition as pyrolysis temperature increases, with the activation energy of ∼3.6 eV. We conclude that the pyrolysis-temperature induced increase in the conductivity is mainly due to the increase in the conductivity of the free carbon. A simple model is proposed to correlate the two.

A novel method is presented in this paper to precisely characterize the dielectric properties of silicon carbon nitride (SiCN) ceramic materials at high temperatures for wireless passive sensing applications. This technique is based on a high quality factor ( Q ) dielectrically loaded cavity resonator, which allows for accurate characterization of both dielectric constant and loss tangent. The dielectric properties of SiCN ceramics are characterized from 25 °C to 1000 °C. Two different metallization processes are implemented for the measurements with the highest temperatures of 500 °C and 1000 °C, respectively. A custom-made thru-reflect-line calibration kit is used to maximize the measurement accuracy at every temperature point. It is observed that the dielectric constant and loss tangent of the SiCN sample without Boron doping increase from 3.707 to 3.883 and from 0.0038 to 0.0213, respectively, when the temperature is raised from 25 °C to 500 °C, and for the SiCN with Boron doping (SiBCN), the dielectric constant and loss tangent increase from 4.817 to 5.132 and from 0.0020 to 0.0186, respectively, corresponding to the temperature ranging from 25 °C to 1000 °C. Experimental uncertainties for extracted ε r and tanδ are no more than 0.0004 and 0.0001, respectively. The temperature dependency of Si(B)CN dielectric properties, as well as the dielectrically loaded cavity resonator structure, provides the basis for the development of wireless passive temperature sensors for high-temperature applications.

The volume of cochlea receiving a specified dose can be an important predictor for hearing preservation in stereotactic radiosurgery (SRS) of vestibular schwannomas (VS). This study evaluates those dosimetric parameters as computed by different dose algorithms in Gamma-knife radiosurgery. Hearing loss is the major risk of complication in SRS of VS. Radiation dose to the cochlea can be a significant factor that causes deterioration in hearing after radiosurgery. A statistical correlation has been observed between some cochlea dose parameters and hearing preservation in gamma-knife treatments. Kato et al found a cutoff dose of 4.2 Gy to the central cochlea for hearing preservation. Brown et al reported the dose-volume predictor for hearing preservation to be a mean cochlea dose of 5.1 Gy, and the mean percentage of the cochlea volume receiving a dose greater than 3.7 Gy, 4.7 Gy and 5.3 Gy to be 64%, 45% and 36%, respectively. In addition, they also discovered that every 10% increase in cochlea volume irradiated would result in a 1.68-dB decrease in the pure tone average (PTA). Advances in modern planning software have improved the accuracy in dose calculation. Such improvements can have a considerable impact on the data published earlier. Gamma-knife planning software underwent a major upgrade recently in which the dose calculation algorithm was refined from TMR Classic to TMR 10. The latter algorithm is more accurate due to a better modeling of scatter. In this study, we retrospectively calculated three VS cases treated with the gamma-knife by both TMR classic and TMR 10. Dose-volume parameters for the cochlea, cited for hearing preservation, are compared and evaluated. The cochlea dose parameters that are considered as the predictor for hearing preservation are extracted from the dose volume histogram (DVH) as calculated by both TMR Classic and TMR 10 algorithms. In addition, the maximum point dose to the cochlea is also included. Among the three cases, the maximum difference for V3.7Gy, V4.7Gy and V5.3Gy between the two dose algorithms is 12%, 10% and 7%, respectively. The difference in mean dose and maximum point dose is less than 0.5 Gy. Substantial deviations in dose-volume predictors have been observed when they are calculated using the newly implemented dose algorithm TMR 10 in the gamma-knife planning system, underscoring the importance of accurate dose calculations. As particular dose parameters in the cochlea are critical for hearing preservation in SRS of VS, clinicians should take into account the change in the values of those dose tolerance predictors that were derived from TMR Classic algorithm. New data should be collected and analyzed to test those published criteria.

A wireless passive sensing approach is proposed to measure the resonant frequency of a dielectrically-loaded cavity resonator. This resonator is made of SiCN ceramic material which is very stable inside harsh environments with temperatures up to 1500°C. The resonator is coupled to CPW lines with one antenna placed at each end of the CPW lines. A wide-band signal is transmitted through two antenna pairs and passes the resonator with the maximum transfer of energy at the resonant frequency of the resonator, i.e. 12.6 GHz. This allows for measuring the resonant frequency of the resonator in a wireless manner. Measurement results are provided for distances up to 40 mm with good agreement with simulations. The proposed methodology is aimed for temperature/pressure sensor development inside gas turbine engines.

In this article, we report a simple technique for synthesizing spherical non‐oxide silicon carbonitride ceramic particles from a polysilazane precursor. In this technique, the spherical particles of the polysilazane precursor were synthesized first via a precipitation polymerization process and then converted to ceramic particles by pyrolysis. The resultant ceramic particles exhibited a close‐to‐perfect spherical shape and a narrow size distribution around 430 nm. The precipitation and pyrolysis processes were characterized using SEM, TEM, FTIR, and XRD to illustrate the formation mechanisms of the ceramic particles.

Glycosylation is one of the most important and common forms of protein posttranslational modifications, which is involved in many physiological functions and biological pathways. However, characterization of glycoproteome in complex biological samples, such as plasma/serum and tissue, is analytically challenging due to the enormous complexity of protein and glycan constituents. Here we report our latest progress of high-throughput N-glycopeptide profiling in serum. Serum sample was enriched by sepharose for subsequent N-glycoproteomics analysis. After profiling of de-glycopeptides and glycans, homemade software GRIP (Glycopeptide Revealing & Interpretation Platform) used these information and novel algorithm, which is designed for glycopeptides "sequence tag" searching and composition interpretation, for LTQ-OrbitrapCID MS/MS spectra. After that, HCD fragmentation was performed as the validation for those glycopeptides resulting from GRIP.

For p > 3 an odd prime, let Gamma be a congruence subgroup between Gamma(1)(p) and Gamma(0)(p). In this article, we give an explicit basis for the group of modular units on X(Gamma) that have divisors defined over Q. As an application, we determine the order of the cuspidal Q-rational torsion subgroup of J(Gamma) generated by the divisor classes of cuspidal divisors of degree 0 defined over Q.

A novel technique is presented in this paper to precisely characterize silicon carbonitride (SiCN) ceramic materials at high temperatures for wireless passive sensing applications. This technique is based on a high quality (Q) factor resonator method, which allows accurate characterization of both dielectric constant and loss tangent. SiCN ceramic materials are measured from 50°C up to 500°C. It is observed that the dielectric constant of SiCN increases from 3.71 to 3.87, corresponding to a temperature range between 50 and 500°C. This temperature-dependent dielectric constant behavior provides the basis for the development of wireless passive temperature sensors in high-temperature applications.