Fiber structures from hydrothermal treatment of cellulose nanocrystalline

Cellulose is the most abundant and inexpensive material available for chemical synthesis. Hydrothermal treatment of cellulose nanocrystal can resemble the nature carbonization process of carbon species. Recently, carbon nanotubes are reported to be successfully synthesized from hydrothermal treatment of carbon species. We then carefully carry the hydrothermal treatment of cellulose nano crystalline and analysis the product. Fibers resemble single wall carbon nanotube structure were observed under Atomic Force Microscopy. Raman Spectroscopy and Transmission Electron Microscopy results show more information about the fibers, which may further prove our assumption to use cellulose nano crystalline to synthesis single wall nanotube in mild hydrothermal treatment conditions

Synthesis, Application and Protein Nanomaterial Interactions of Selected Nanofiber, Nanoparticle and Nanoarray

Nanomaterials have been a hot research topic for past decades due to their unique optical, electronic, catalytic and mechanical properties. This dissertation aims to investigate selected aspects of nanomaterial synthesis, application and protein nanomaterial interactions. We target to improve nanomaterials synthesis, explore their novel applications and study their potential hazardous. Chapter 1 describes new hydrothermal synthesis of carbon nanofibers from cellulose nanocrystals. The described hydrothermal synthesis from cellulose is an environmentally friendly method that has commercial potential for inexpensive production of carbon nanofibers. Chapter 2 describes the application of poly(methyl methacrylate) (PMMA) stabilized 2D AgNP array for measuring changes of bulk refractive index and sensing of selected volatile organic compound (VOC). The PMMA stabilized 2D AgNP array gives linear response to bulk refractive index changes and can be re-used after rinsing with water. Responsive polymer films were spin-coated on PMMA stabilized 2D AgNP array to fabricate the nanocomposite films. These nanocomposite films exhibit sharp coherent plasmon coupling, spectra position of which is affected by the changes of local dielectric environment when interacting with VOC vapors. Chapter 3 describes studies related to the interaction of AgNP and AuNP with cytoskeleton protein (actin and tubulin), immune system protein (complementary component 3) and plasma protein (albumin and fibronegen). The nanoparticle protein interaction is influenced by both nanoparticle and protein sizes. The work presented here establishes basic knowledge related to nanomaterial synthesis and their advanced applications

Deriving detector-specific correction factors for rectangular small fields using a scintillator detector

The goal of this study was to investigate small field output factors (OFs) for flat-tening filter-free (FFF) beams on a dedicated stereotactic linear accelerator-based system. From this data, the collimator exchange effect was quantified, and detector-specific correction factors were generated. Output factors for 16 jaw-collimated small fields (from 0.5 to 2 cm) were measured using five different detectors including an ion chamber (CC01), a stereotactic field diode (SFD), a diode detector (Edge), Gafchromic film (EBT3), and a plastic scintillator detector (PSD, W1). Chamber, diodes, and PSD measurements were performed in a Wellhofer water tank, while films were irradiated in solid water at 100 cm source-to-surface distance and 10 cm depth. The collimator exchange effect was quantified for rectangular fields. Monte Carlo (MC) simulations of the measured configurations were also performed using the EGSnrc/DOSXYZnrc code. Output factors measured by the PSD and verified against film and MC calculations were chosen as the benchmark measurements. Compared with plastic scintillator detector (PSD), the small volume ion chamber (CC01) underestimated output factors by an average of -1.0% ± 4.9% (max. = -11.7% for 0.5 × 0.5 cm2 square field). The stereotactic diode (SFD) overestimated output factors by 2.5% ± 0.4% (max. = 3.3% for 0.5 × 1 cm2 rectangular field). The other diode detector (Edge) also overestimated the OFs by an average of 4.2% ± 0.9% (max. = 6.0% for 1 × 1 cm2 square field). Gafchromic film (EBT3) measure-ments and MC calculations agreed with the scintillator detector measurements within 0.6% ± 1.8% and 1.2% ± 1.5%, respectively. Across all the X and Y jaw combinations, the average collimator exchange effect was computed: 1.4% ± 1.1% (CC01), 5.8% ± 5.4% (SFD), 5.1% ± 4.8% (Edge diode), 3.5% ± 5.0% (Monte Carlo), 3.8% ± 4.7% (film), and 5.5% ± 5.1% (PSD). Small field detectors should be used with caution with a clear understanding of their behaviors, especially for FFF beams and small, elongated fields. The scintillator detector exhibited good agreement against Gafchromic film measurements and MC simulations over the range of field sizes studied. The collimator exchange effect was found to be impor-tant at these small field sizes. Detector-specific correction factors were computed using the scintillator measurements as the benchmark

Targeting Accuracy of Image-Guided Radiosurgery for Intracranial Lesions: A Comparison Across Multiple Linear Accelerator Platforms

PURPOSE: To evaluate the overall positioning accuracy of image-guided intracranial radiosurgery across multiple linear accelerator platforms. METHODS: A computed tomography scan with a slice thickness of 1.0 mm was acquired of an anthropomorphic head phantom in a BrainLAB U-frame mask. The phantom was embedded with three 5-mm diameter tungsten ball bearings, simulating a central, a left, and an anterior cranial lesion. The ball bearings were positioned to radiation isocenter under ExacTrac X-ray or cone-beam computed tomography image guidance on 3 Linacs: (1) ExacTrac X-ray localization on a Novalis Tx; (2) cone-beam computed tomography localization on the Novalis Tx; (3) cone-beam computed tomography localization on a TrueBeam; and (4) cone-beam computed tomography localization on an Edge. Each ball bearing was positioned 5 times to the radiation isocenter with different initial setup error following the 4 image guidance procedures on the 3 Linacs, and the mean (µ) and one standard deviation (σ) of the residual error were compared. RESULTS: Averaged overall 3 ball bearing locations, the vector length of the residual setup error in mm (µ ± σ) was 0.6 ± 0.2, 1.0 ± 0.5, 0.2 ± 0.1, and 0.3 ± 0.1 on ExacTrac X-ray localization on a Novalis Tx, cone-beam computed tomography localization on the Novalis Tx, cone-beam computed tomography localization on a TrueBeam, and cone-beam computed tomography localization on an Edge, with their range in mm being 0.4 to 1.1, 0.4 to 1.9, 0.1 to 0.5, and 0.2 to 0.6, respectively. The congruence between imaging and radiation isocenters in mm was 0.6 ± 0.1, 0.7 ± 0.1, 0.3 ± 0.1, and 0.2 ± 0.1, for the 4 systems, respectively. CONCLUSIONS: Targeting accuracy comparable to frame-based stereotactic radiosurgery can be achieved with image-guided intracranial stereotactic radiosurgery treatment

Evaluation and verification of the QFix Encompass couch insert for intracranial stereotactic radiosurgery

The QFix EncompassTM stereotactic radiosurgery (SRS) immobilization system consists of a thermoplastic mask that attaches to the couch insert to immobilize patients treated with intracranial SRS. This study evaluates the dosimetric impact and verifies a vendor provided treatment planning system (TPS) model in the Eclipse TPS. A thermoplastic mask was constructed for a Lucy 3D phantom, and was scanned with and without the EncompassTM system. Attenuation measurements were performed in the Lucy phantom with and without the insert using a pinpoint ion chamber for energies of 6xFFF, 10xFFF and 6X, with three field sizes (2 × 2, 4 × 4, and 6 × 6 cm2 ). The measurements were compared to two sets of calculations. The first set utilized the vendor provided Encompass TPS model (EncompassTPS ), which consists of two structures: the Encompass and Encompass base structure. Three HU values for the Encompass (200, 300, 400) and Encompass Base (-600, -500, -400) structures were evaluated. The second set of calculations consists of the Encompass insert included in the external body contour (EncompassEXT ) for dose calculation. The average measured percent attenuation in the posterior region of the insert ranged from 3.4%-3.8% for the 6xFFF beam, 2.9%-3.4% for the 10xFFF, and 3.3%-3.6% for the 6X beam. The maximum attenuation occurred at the region where the mask attaches to the insert, where attenuation up to 17% was measured for a 6xFFF beam. The difference between measured and calculated attenuation with either the EncompassEXT or EncompassTPS approach was within 0.5%. HU values in the EncompassTPS model that provided the best agreement with measurement was 400 for the Encompass structure and -400 for the Encompass base structure. Significant attenuation was observed at the area where the mask attaches to the insert. Larger differences can be observed when using few static beams compared to rotational treatment techniques

Optimization of Treatment Geometry to Reduce Normal Brain Dose in Radiosurgery of Multiple Brain Metastases with Single-Isocenter Volumetric Modulated Arc Therapy

Treatment of patients with multiple brain metastases using a single-isocenter volumetric modulated arc therapy (VMAT) has been shown to decrease treatment time with the tradeoff of larger low dose to the normal brain tissue. We have developed an efficient Projection Summing Optimization Algorithm to optimize the treatment geometry in order to reduce dose to normal brain tissue for radiosurgery of multiple metastases with single-isocenter VMAT. The algorithm: (a) measures coordinates of outer boundary points of each lesion to be treated using the Eclipse Scripting Application Programming Interface, (b) determines the rotations of couch, collimator, and gantry using three matrices about the cardinal axes, (c) projects the outer boundary points of the lesion on to Beam Eye View projection plane, (d) optimizes couch and collimator angles by selecting the least total unblocked area for each specific treatment arc, and (e) generates a treatment plan with the optimized angles. The results showed significant reduction in the mean dose and low dose volume to normal brain, while maintaining the similar treatment plan qualities on the thirteen patients treated previously. The algorithm has the flexibility with regard to the beam arrangements and can be integrated in the treatment planning system for clinical application directly

Dosimetric Evaluation of Fractionated Stereotactic Radiation Therapy for Skull Base Meningiomas Using HyperArc and Multicriteria Optimization

Purpose: Treatment planning of skull based meningiomas can be difficult due to the irregular shaped target volumes and proximity to critical optic structures. This study evaluated the use of HyperArc (HA) radiosurgery optimization and delivery in conjunction with multicriteria optimization (MCO) to create conformal and efficient treatment plans for conventionally fractionated radiation therapy to difficult base-of-skull (BOS) lesions. Methods and Materials: Twelve patients with BOS meningioma were retrospectively planned with HA-specific optimization algorithm, stereotactic normal tissue objective (SRS-NTO), and conventional automatic normal tissue objective to evaluate normal brain sparing (mean dose and V20 Gy). MCO was used on both SRS-NTO and automatic normal tissue objective plans to further decrease organ-at-risk doses and target dose maximum to within clinically acceptable constraints. Delivery efficiency was evaluated based on planned monitor units. Results: The SRS-NTO in HA can be used to improve the mid- and low-dose spread to normal brain tissue in the irradiation of BOS meningiomas. Improvement in normal brain sparing can be seen in larger, more irregular shaped lesions and less so in smaller spherical targets. MCO can be used in conjunction with the SRS-NTO to reduce target dose maximum and dose to organ at risk without sacrificing the gain in normal brain sparing. Conclusions: HA can be beneficial both in treatment planning by using the SRS-NTO and in delivery efficiency through the decrease in monitor units and automated delivery

Improving the Efficacy of Conventional Therapy by Adding Andrographolide Sulfonate in the Treatment of Severe Hand, Foot, and Mouth Disease: A Randomized Controlled Trial

Background. Herb-derived compound andrographolide sulfonate (called Xiyanping injection) recommended control measure for severe hand, foot, and mouth disease (HFMD) by the Ministry of Health (China) during the 2010 epidemic. However, there is a lack of good quality evidence directly comparing the efficacy of Andrographolide Sulfonate combination therapy with conventional therapy. Methods. 230 patients were randomly assigned to 7–10 days of Andrographolide Sulfonate 5–10 mg/Kg/day and conventional therapy, or conventional therapy alone. Results. The major complications occurred less often after Andrographolide Sulfonate (2.6% versus 12.1%; risk difference [RD], 0.94; 95% CI, 0.28–1.61; P=0.006). Median fever clearance times were 96 hours (CI, 80 to 126) for conventional therapy recipients and 48 hours (CI, 36 to 54) for Andrographolide Sulfonate combination-treated patients (χ2=16.57, P<0.001). The two groups did not differ in terms of HFMD-cause mortality (P=1.00) and duration of hospitalization (P=0.70). There was one death in conventional therapy group. No important adverse event was found in Andrographolide Sulfonate combination therapy group. Conclusions. The addition of Andrographolide Sulfonate to conventional therapy reduced the occurrence of major complications, fever clearance time, and the healing time of typical skin or oral mucosa lesions in children with severe HFMD