Ultrafast and Nonlinear Spectroscopy of Nanomaterials

Ultrafast and nonlinear spectroscopies are implemented in the investigation of excited-state dynamics and structural properties of materials and nanomaterials. In the first study, the excited-state dynamics of size-dependent colloidal TiO2-Au nanocomposites are investigated using ultrafast transient absorption spectroscopy. The dynamics corresponding to the plasmon depletion band are characterized by electron-phonon and phonon-phonon coupling lifetimes that are observed to be independent of the gold nanocluster shell thickness. The excited-state dynamics corresponding to the interband transition of gold is also spectrally overlapped with the interfacial electron transfer lifetime, which is shown to decrease as the nanocluster shell thickness increases. In the second study, in-situ second harmonic generation (SHG), a nonlinear spectroscopic technique, is coupled with extinction spectroscopy to monitor the growth of colloidal gold nanoparticles in real time. The in-situ SHG results capture an early stage of the growth process where a large enhancement in the SHG is observed due to the formation of plasmonic hot spots attributed to a rough and uneven nanoparticle surface. In a third project, the ultrafast carrier dynamics of self-assembled La1-xSrxTiO3-δ (LMSO) is studied using ultrafast reflectivity experiments. The measured long-lived phonon-phonon coupling lifetime for the oxygen deficient LSMO thin film indicates that the phonons are the major energy carrier in the system. Residual oscillations of two distinct phonon frequencies are also observed and are superimposed on a biexponential decay. Both oscillatory signals are fit with an exponentially damping sine function in which both frequency and damping times are obtained. In a fourth project, our ultrafast reflectivity setup is modified with an added microscopy component for our work with the Consortium for Innovation in Manufacturing and Materials (CIMM) to investigate heating and melting dynamics of metals, semiconductors, and metal alloys. Finally, in the last portion of this dissertation, electronic sum-frequency generation spectroscopy is utilized to study the azimuthal angular dependence in α-quartz (0001). This dissertation describes the versatility of these ultrafast and nonlinear spectroscopic techniques through fundamental research on different types of materials and nanomaterials in colloidal suspension and at surfaces

Vertebral Augmentation: State of the Art

Osteoporotic vertebral compression fractures (OVF) are an increasing public health problem. Cement augmentation (vertebroplasty of kyphoplasty) helps stabilize painful OVF refractory to medical treatment. This stabilization is thought to improve pain and functional outcome. Vertebroplasty consists of injecting cement into a fractured vertebra using a percutaneous transpedicular approach. Balloon kyphoplasty uses an inflatable balloon prior to injecting the cement. Although kyphoplasty is associated with significant improvement of local kyphosis and less cement leakage, this does not result in long-term clinical and functional improvement. Moreover, vertebroplasty is favored by some due to the high cost of kyphoplasty. The injection of cement increases the stiffness of the fracture vertebrae. This can lead, in theory, to adjacent OVF. However, many studies found no increase of subsequent fracture when comparing medical treatment to cement augmentation. Kyphoplasty can have a protective effect due to restoration of sagittal balance

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

A rare case of right lower quadrant abdominal pain.

Isolated fallopian tube torsion without involvement of the ovary is a rare condition most frequently presenting during reproductive years. Imaging, vitals, physical exam, and laboratory findings all fail to help establish a definitive diagnosis. The majority of the diagnoses are made on the operating table. Physical exam most often reveals unilateral and localized abdominal pain, often with nausea and vomiting, but few other reliably common findings. Diagnosis becomes even more challenging due to the fact that isolated tubal torsion occurs often in pregnancy and preferentially on the right, further complicating the clinical picture. We describe a case of isolated tubal torsion, unique in that localized necrosis and inflammation from the torsion triggered a secondary appendicitis. The patient required surgical intervention, and an appendectomy and salpingectomy emergently. Given its elusive and rare nature, awareness and early intervention is required by the emergency physician to recognize tubal torsion, as operative intervention is crucial, and can lead to preservation of fertility and improved fetal survival

Excited-state dynamics of size-dependent colloidal TiO\u3csub\u3e2\u3c/sub\u3e-Au nanocomposites

© 2016 AIP Publishing LLC. The ultrafast excited-state dynamics of size-dependent TiO2-Au nanocomposites synthesized by reducing gold nanoclusters to the surface of colloidal TiO2 nanoparticles are studied using pump-probe transient absorption spectroscopy with 400 nm excitation pulses. The results show that the relaxation processes of the plasmon depletion band, which are described by electron-phonon and phonon-phonon scattering lifetimes, are independent of the gold nanocluster shell size surrounding the TiO2 nanoparticle core. The dynamics corresponding to interfacial electron transfer between the gold nanoclusters and the TiO2 bandgap are observed to spectrally overlap with the gold interband transition signal, and the electron transfer lifetimes are shown to significantly decrease as the nanocluster shell size increases. Additionally, size-dependent periodic oscillations are observed and are attributed to acoustic phonons of a porous shell composed of aggregated gold nanoclusters around the TiO2 core, with frequencies that decrease and damping times that remain constant as the nanocluster shell size increases. These results are important for the development of improved catalytic nanomaterial applications

Large Cell Neuroendocrine Carcinoma of the Bladder with Adenocarcinomatous Component

Large cell neuroendocrine carcinoma (LCNC) is one of the rarest types of bladder cancer occurring in <1%. Either pure or mixed with another component, it remains one of the most aggressive types of bladder cancer. We report a case of LCNC of the bladder with an adenocarcinomatous component. The patient was a 64-year-old smoker male, who presented for the first time with dysuria and hematuria. A bladder tumor invading the anterior and right lateral bladder walls was discovered, without any secondary localizations. Tumor biopsy showed an LCNC with adenocarcinomatous components. The patient was treated by recurrent tumor resections, chemotherapy, and radiotherapy. No improvement was noted despite close follow-up and adequate treatment. Neuroendocrine bladder tumor is known to have an aggressive, rapid, and disadvantageous evolution. Multiple case reports were published so far, and a recent review was conducted in March 2020 by Sanguedolce et al. (2020). More cases are needed to establish the best management plan for this type of tumor

Bellini Duct Carcinoma Misdiagnosed with Urothelial Papillary Carcinoma

Background. Collecting (Bellini) duct carcinoma (CDC) or Bellini duct carcinoma (BDC) is a rare subtype of kidney tumors, accounting for less than 3% and known to have the worst prognosis. It is known to have multiple clinical presentations; this is why it can be easily misdiagnosed. The aim of this article is to present a case of CDC that was initially misdiagnosed with urothelial papillary carcinoma (UPC) in a 41-year-old male. Case Presentation. Our patient presented with a left flank pain evolving for one month and one episode of gross macroscopic hematuria. Upon presentation, he had left costovertebral angle tenderness. Initial lab tests were normal. Computed tomography revealed a 5 cm solid mass of the left renal pelvis and multiple infracentimetric perihilar lymph nodes. Subsequently, the patient had left nephroureterectomy. Microscopic examination showed the presence of a high-grade urothelial papillary carcinoma of the renal pelvis’ lumen. All four of the dissected lymph nodes showed disease metastasis. Three years after establishing the diagnosis, the patient presented again for chronic abdominal pain, with a recent history of weight loss. CT scan showed a left paraaortic mass infiltrating the left psoas muscle over a length of 12 cm. Immunohistochemical profiling of this mass confirmed the diagnosis of Bellini duct carcinoma, rejecting the initial diagnosis of UPC. Therefore, the patient required a cisplatin-gemcitabine-based chemotherapy regimen. Conclusion. BDC remains one of the rare aggressive subtypes of RCC, having a multitude of initial clinical presentations and an unfavorable prognosis. In this patient, CDC was masquerading as a transitional cell carcinoma that should always be kept in mind as a possible presentation. Corresponding early imaging and histopathology exams are primordial for a correct diagnosis and thus a better prognosis