Sharp weighted bounds for one-sided and multiple integral operators

In this paper we establish sharp weighted bounds (Buckley type theorems) for one{sided maximal and fractional integral operators in terms of one{sided $A_p$ characteristics. Appropriate sharp bounds for strong maximal functions, multiple potentials and singular integrals are derived

Impact of adjacent dielectrics on the high-frequency performance of graphene field-effect transistors

Transistors operating at high frequencies are the basic building blocks of millimeter wave communication and sensor systems. The high velocity and mobility of carriers in graphene can open ways for development of ultra-fast group IV transistors with similar or even better performance than that achieved with III-V based semiconductors. However, the progress of high-speed graphene transistors has been hampered by limitations associated with fabrication, influence of adjacent materials and self-heating effects.This thesis work presents results of the comprehensive analysis of the influence of material imperfections, self-heating and limitations of the charge carrier velocity, imposed by adjacent dielectrics, on the transit frequency, fT, and the maximum frequency of oscillation, fmax, of graphene field-effect transistors (GFETs). The analysis allowed for better understanding and developing a strategy for addressing the limitations.In particular, it was shown that the GFET high-frequency performance can be enhanced by utilizing the gate and substrate dielectric materials with higher optical phonon (OP) energy, allowing for higher saturation velocity and, hence, higher fT and fmax. This approach was experimentally verified by demonstration of enhancement in the fT and fmax in GFETs with graphene channel encapsulated by the Al2O3 layers. As a further step, GFETs on diamond, material with highest OP energy and thermal conductivity, were introduced, developed and fabricated, showing the extrinsic fmax up to 50 GHz, at the gate length of 0.5 \ub5m, which is highest reported so far among the best published graphene and semiconductor counterparts.The main achievements of this thesis work are as follows: (i) comprehensive study of correlations between graphene-dielectric material quality, small-signal equivalent circuit parameters and high-frequency performance of the GFETs; (ii) experimental verification of the concept of improving the GFET high- frequency performance via selection of adjacent dielectric materials with high OP energy; (iii) introducing the diamond as a most promising dielectric material for high-frequency GFETs; (iv) development of technology and demonstration of fully integrated X and Ku band GFET IC amplifiers with state-of-the art performance.In conclusion, the routes of future development depicted in this thesis work may allow for enhancing the high-frequency performance of GFETs up to the level or even higher than that of the modern III-V semiconductor counterparts

Effect of Biofertilizer and Plant Spacing on Growth, Yield and Fruit Quality of Brinjal (Solanum melongena L.)

A field experiment “effect of biofertilizer and plant spacing on growth, yield and fruit quality of brinjal” was carried out. Four Biofertilizer levels (B1:0, B2: 6.5, B3: 8.5 and B4: 10.5L ha-1) and four Plant spacing (S1: 60×30, S2: 60×60, S3: 60×90 and S4: 60×120cm) were used. A Randomize Complete Block Design (RCBD) with split-plot arrangement was used in such a way that biofertilizer levels were subjected to main plots and plant spacing was allotted to sub plots. Biofertilizers and plant spacing significantly (P≤0.05) affected most of the attributes studied. Among the Biofertilizer treatments, maximum plant height (108.72cm), number of leaves plant-1(135.33), leaf area (90.73cm2), fruit weight (99.36gm), yield plant-1 (1.77kg), total yield (37.21tons ha-1), fruit pH (5.59), vitamin C (3.00mg) and fruit firmness (2.06kg cm-2) were recorded in biofertilizer application @6.5L ha-1. In case of different plant spacing maximum plant height (102.35cm), number of  leaves plant-1 (123.45), leaf area (86.41cm2), fruit weight plant-1 (89.54gm), yield plant-1 (1.63kg), total yield (40.64tons ha-1), fruit pH (5.44), vitamin C (2.70mg) and fruit firmness (2.05kg cm-2) were recorded in 60x60 cm. It is concluded that biofertilizer application @6.5 L ha-1 with plant spacing 60x60 cm increased the qualitative and quantitative attributes of brinjal. Keywords: Brinjal, biofertilizer, plant spacing, growth, yield, quality

Graphene field-effect transistors for high frequency applications

Rapid development of wireless and internet communications requires development of new generation high frequency electronics based on new device concepts and new materials. The very high intrinsic velocity of charge carriers in graphene makes it promising new channel material for high frequency electronics.In this thesis, the graphene field-effect transistors (GFETs) are fabricated using chemical vapor deposition (CVD) graphene and investigated for high frequency electronics applications. The characterization and simulation of high frequency performance of the state-of-the-art GFETs devices are given. A modified fabrication process is used. This allows for preserving intrinsic graphene properties in the GFET channel and, simultaneously, achieving extremely low graphene/metal contact resistance. As a result, GFETs with state-of-the-art high frequency performance were fabricated and used in further analysis for development of GFETs with continuously improved performance.In particular, the dependencies between the material quality and the high-field high-frequency performance of GFETs fabricated on Si chip have been studied. It was shown, that the low-field carrier mobility can be selected as the material quality parameter. The high-frequency performance of GFETs is characterized by fT and fmax. The surface distribution of the graphene/dielectric material quality across the chip has been exploited as a tool to study the dependencies of GFET high-frequency performance on the material quality. The fT and fmax increase in the range of 20-40 GHz with low-field mobility in the range of 600-2000 cm2/V s. The dependencies are analyzed by combining the models of the drain resistance, carrier velocity, saturation velocity and small-signal equivalent circuit. Additionally, this allows for clarifying the effects of the equivalent-circuit parameters, such as contact resistance (Rc), transconductance (gm) and differential drain conductance (gds), on the fT and fmax. The observed variations of fT and fmax are mainly governed by corresponding variations of gm and gds. Analysis allows for identifying a most promising approach for improving the GFET high-frequency performance, which is selection of adjacent dielectric materials with optical phonon energy higher than that of SiO2, resulting in higher saturation velocity and, hence, higher fT and fmax

“EFFECT OF IRRADIATION ON THE IMMUNOREGULATORY FUNCTIONS EXERTED BY TUMOUR FIBROBLASTS ON MACROPHAGES”

Summary Background/aim of the study: Carcinoma-associated fibroblasts (CAFs) represents a heterogeneous population of cells and are considered one of the dominant stromal component of solid tumours, performing a crucial role in tumour proliferation and metastasis. The main objective of this study was to investigate the immunoregulatory features of CAFs isolated from non-small cell lung carcinomas on macrophages and the potential effects of ionizing radiation on observed effects. Methods: The study comprise primary cultures of CAFs isolated from freshly resected NSCLC (Non Small Lung Cancer) tumours (n=8) and monocyte-derived macrophages prepared from peripheral blood of healthy donors. The experimental settings included both co-cultures and incubations of macrophages with CAF-conditioned medium. Moreover, CAF-mediated effects were studied in both uncommitted and M1-polarized macrophages. Functional assays to study macrophage polarisation included expression of cell surface markers by flow cytometry, production of nitric oxide by flow cytometry and secretion of inflammatory cytokines by ELISA. Results: All functional assays illustrated that CAFs both in co-culture and by conditioned medium, promote changes on uncommitted macrophages (M0) that harmonize with both M1 and M2 phenotypes. CAFs, both in co-culture and by conditioned medium, could inhibit some of the pro-inflammatory features of M1 macrophages as demonstrated by strong inhibition of nitric oxide production, strong inhibition of proinflammatory cytokines secretion and a reduction of some M1 surface markers. Importantly, radiation given at high dose (1x18 Gy) or in fractioned regimens (3x6 Gy) is not able to modify substantially the immunoregulatory features exerted by CAFs over macrophages in vitro. Last, protein expression analyses in CAF supernatants show that both irradiated and non-irradiated CAFs produced approximately the same levels of cytokines. Conclusion: This study display that CAFs-derived soluble factors mediate measurable changes on uncomitted macrophages (M0) and down-regulate pro-inflammatory features of M1 polarized macrophages, even though the soluble factors accountable for this shift remains unknown. On the other hand, this study also illustrates that low dose fractioned radiotherapy and single high dose radiotherapy do not curtail the immunosuppressive effect of CAFs