Laboratory Characterization of Geomechanical and Hydraulic Properties of Deep-Sea Hydrate Deposits

Methane hydrate has been considered as a future energy resource due to the vast amount of carbon in the natural hydrate reservoirs. During gas production from deep-sea hydrate deposits via depressurization, the effective stress of hydrate-bearing sediments can increase and alter the mechanical, physical, and hydraulic properties of the sediments. This thesis explores the geomechanical and hydraulic properties of tetrahydrofuran hydrate-bearing sand specimens subjected to high effective stress. Specifically, the focus is placed on understanding the role of hydrate crystals on the compressibility, particle grain crushing, wave velocity, the coefficient of earth pressure at rest, and permeability anisotropy in hydrate-bearing sediments. This thesis also explores hydrate morphology in clayey sediments and ensued geophysical properties using X-ray computed tomography and elastic wave measurements. The major findings of this thesis include: (i) the presence of hydrate crystals restrains particle rotation and rearrangement during loading, resulting in less pronounced particle crushing in sediments with higher hydrate saturation; (ii) the coefficient of earth pressure at rest K0 is mainly affected by hydrate saturation and applied vertical stress levels, and the cementation effect and the creep behavior of hydrate crystals play a vital roles in the evolution of K0; (iii) the permeability anisotropy of hydrate-bearing sediments increases exponentially with the increase of effective vertical stress under the oedometer condition, implying that vertical direction permeameter tests may underestimate the reservoir’s flow performance; and (iv) the morphology and hydrate saturation of tetrahydrofuran hydrate in clayey sediments are affected by the nucleation induction time, and the sediments with higher hydrate saturation attenuate P- and S-waves more significantly. These findings are expected to provide a comprehensive understanding of the geotechnical and the hydraulic behavior of hydrate-bearing specimens under high effective stress conditions and wave-based characterization of hydrate-bearing clayey specimens.Ph.D

Visualizing Quaternion Multiplication

Quaternion rotation is a powerful tool for rotating vectors in 3-D; as a result, it has been used in various engineering fields, such as navigations, robotics, and computer graphics. However, understanding it geometrically remains challenging, because it requires visualizing 4-D spaces, which makes exploiting its physical meaning intractable. In this paper, we provide a new geometric interpretation of quaternion multiplication using a movable 3-D space model, which is useful for describing quaternion algebra in a visual way. By interpreting the axis for the scalar part of quaternion as a 1-D translation axis of 3-D vector space, we visualize quaternion multiplication and describe it as a combined effect of translation, scaling, and rotation of a 3-D vector space. We then present how quaternion rotation formulas and the derivative of quaternions can be formulated and described under the proposed approach.112sciescopu

Clinical outcomes of FOLFIRINOX in locally advanced pancreatic cancer: A single center experience

Systemic chemotherapy or chemoradiotherapy is the initial primary option for patients with locally advanced pancreatic cancer (LAPC). This study analyzed the effect of FOLFIRINOX and assessed the factors influencing conversion to surgical resectability for LAPC.Sixty-four patients with LAPC who received FOLFIRINOX as initial chemotherapy were enrolled retrospectively. Demographic characteristics, tumor status, interval/dosage/cumulative relative dose intensity (cRDI) of FOLFIRINOX, conversion to resection, and clinical outcomes were reviewed and factors associated with conversion to resectability after FOLFIRINOX were analyzed.After administration of FOLFIRINOX (median 9 cycles, 70% of cRDI), the median patient overall survival (OS) was 17.0 months. Fifteen of 64 patients underwent surgery and R0 resection was achieved in 11 patients. During a median follow-up time of 9.4 months after resection, cumulative recurrence rate was 28.5% at 18 months after resection. The estimated median OS was significantly longer for the resected group (>40 months vs 13 months). There were no statistical differences between the resected and non-resected groups in terms of baseline characteristics, tumor status and hematologic adverse effects. The patients who received standard dose of FOLFIRINOX had higher probability of subsequent resection compared with patients who received reduced dose, although cRDIs did not differ between groups.FOLFIRINOX is an active regimen in patients with LAPC, given acceptable resection rates and promising R0 resection rates. Additionally, our data demonstrate it is advantageous for obtaining resectability to administer FOLFIRINOX without dose reduction

Interactions between Cells with Distinct Mutations in c-MYC and Pten in Prostate Cancer

In human somatic tumorigenesis, mutations are thought to arise sporadically in individual cells surrounded by unaffected cells. This contrasts with most current transgenic models where mutations are induced synchronously in entire cell populations. Here we have modeled sporadic oncogene activation using a transgenic mouse in which c-MYC is focally activated in prostate luminal epithelial cells. Focal c-MYC expression resulted in mild pathology, but prostate-specific deletion of a single allele of the Pten tumor suppressor gene cooperated with c-MYC to induce high grade prostatic intraepithelial neoplasia (HGPIN)/cancer lesions. These lesions were in all cases associated with loss of Pten protein expression from the wild type allele. In the prostates of mice with concurrent homozygous deletion of Pten and focal c-MYC activation, double mutant (i.e. c-MYC+;Pten-null) cells were of higher grade and proliferated faster than single mutant (Pten-null) cells within the same glands. Consequently, double mutant cells outcompeted single mutant cells despite the presence of increased rates of apoptosis in the former. The p53 pathway was activated in Pten-deficient prostate cells and tissues, but c-MYC expression shifted the p53 response from senescence to apoptosis by repressing the p53 target gene p21Cip1. We conclude that c-MYC overexpression and Pten deficiency cooperate to promote prostate tumorigenesis, but a p53-dependent apoptotic response may present a barrier to further progression. Our results highlight the utility of inducing mutations focally to model the competitive interactions between cell populations with distinct genetic alterations during tumorigenesis

A Reusable Fuzzy Extractor with Practical Storage Size

After the concept of a Fuzzy Extractor (FE) was rst introduced by Dodis et al. , it has been regarded as one of the candidate solutions for key management utilizing biometric data. With a noisy input such as biometrics, FE generates a public helper value and a random secret key which is reproducible given another input similar to the original input. However, helper values may cause some leakage of information when generated repeatedly by correlated inputs, thus reusability should be considered as an important property. Recently, Canetti et al. (Eurocrypt 2016) proposed a FE satisfying both reusability and robustness with inputs from low-entropy distributions. Their strategy, the so-called Sample-then-Lock method, is to sample many partial strings from a noisy input string and to lock one secret key with each partial string independently. In this paper, modifying this reusable FE, we propose a new FE with size-reduced helper data hiring a threshold scheme. Our new FE also satises both reusability and robustness, and requires much less storage memory than the original. To show the advantages of this scheme, we analyze and compare our scheme with the original in concrete parameters of the biometric, IrisCode. As a result, on 1024-bit inputs, with false rejection rate 0.5 and error tolerance 0.25, while the original requires about 1TB for each helper value, our scheme requires only 300MB with an additional 1.35GB of common data which can be used for all helper values

Nearly 100% Horizontal Dipole Orientation and Upconversion Efficiency in Blue Thermally Activated Delayed Fluorescent Emitters

The relationship between anisotropic orientation and molecular structure of thermally activated delayed fluorescent (TADF)‐based organic light emitting devices (OLEDs) is studied using TADF emitters with carbazole, biscarbazole, and triscarbazole donor units. The bicarbazole and triscarbazole donors are more effective than the carbazole donor in driving the anisotropic orientation of the TADF molecules. A near‐perfect in‐plane orientation of the TADF dipole moment is demonstrated using the triscarbazole donor. In addition, the triscarbazole donor based OLED shows high photoluminescence quantum yield and an upconversion efficiency close to 100%. As a consequence, an external quantum efficiency >30% is obtained.A systematic study correlating donor structure with horizontal dipole orientation of blue triscarbazole thermally activated delayed fluorescent (TADF) emitters shows an exceptionally high horizontal dipole orientation of 95%. The dipole orientation and high photoluminescence quantum yield result in an external quantum efficiency >30% in organic light‐emitting diodes employing these TADF emitters.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145231/1/adom201701340.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/145231/2/adom201701340_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/145231/3/adom201701340-sup-0001-S1.pd

CRYPTO-MINE: Cryptanalysis via Mutual Information Neural Estimation

The use of Mutual Information (MI) as a measure to evaluate the efficiency of cryptosystems has an extensive history. However, estimating MI between unknown random variables in a high-dimensional space is challenging. Recent advances in machine learning have enabled progress in estimating MI using neural networks. This work presents a novel application of MI estimation in the field of cryptography. We propose applying this methodology directly to estimate the MI between plaintext and ciphertext in a chosen plaintext attack. The leaked information, if any, from the encryption could potentially be exploited by adversaries to compromise the computational security of the cryptosystem. We evaluate the efficiency of our approach by empirically analyzing multiple encryption schemes and baseline approaches. Furthermore, we extend the analysis to novel network coding-based cryptosystems that provide individual secrecy and study the relationship between information leakage and input distribution

Systematic Control of the Orientation of Organic Phosphorescent Pt Complexes in Thin Films for Increased Optical Outcoupling

Orienting light‐emitting molecules relative to the substrate is an effective method to enhance the optical outcoupling of organic light‐emitting devices. Platinum(II) phosphorescent complexes enable facile control of the molecular alignment due to their planar structures. Here, the orientation of Pt(II) complexes during the growth of emissive layers is controlled by two different methods: modifying the molecular structure and using structural templating. Molecules whose structures are modified by adjusting the diketonate ligand of the Pt complex, dibenzo‐(f,h)quinoxaline Pt dipivaloylmethane, (dbx)Pt(dpm), show an ≈20% increased fraction of horizontally aligned transition dipole moments compared to (dbx)Pt(dpm) doped into a 4,4′‐bis(N‐carbazolyl)‐1,1′‐biphenyl, CBP, host. Alternatively, a template composed of highly ordered 3,4,9,10‐perylenetetracarboxylic dianhydride monolayers is predeposited to drive the alignment of a subsequently deposited emissive layer comprising (2,3,7,8,12,13,17,18‐octaethyl)‐21H,23H‐porphyrinplatinum(II) doped into triindolotriazine. This results in a 60% increase in horizontally aligned transition dipole moments compared to the film deposited in the absence of the template. The findings provide a systematic route for controlling molecular alignment during layer growth, and ultimately to increase the optical outcoupling in organic light‐emitting diodes.Pt(II) complex orientation is controlled by modifying the molecular structure and structural templating. Molecules with modified structures show ≈20% increased fraction of horizontally aligned transition dipole moments (TDMs) when doped into a host. Alternatively, a highly ordered molecular template drives the alignment of a subsequently deposited polycrystalline emissive layer, showing a 60% increase in horizontally aligned TDMs versus without template.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151333/1/adma201900921.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151333/2/adma201900921_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151333/3/adma201900921-sup-0001-S1.pd