Publications by authors named "Sandip Singh"

The International Subarachnoid Aneurysm Trial led to a shift from clipping to endovascular coiling as the primary therapy for cerebral aneurysm particularly in the management of posterior circulation aneurysm. However, endovascular therapy is often unavailable in low-resource settings, emphasizing the importance of maintaining surgical skill sets in resource-poor countries. This article presents a detailed case report on the successful microneurosurgical management of a 65-year-old female with a history of headache and weakness with past history of hypertension and a right posterior cerebral artery territory infarct who was diagnosed with a ruptured aneurysm situated within the intracranial vertebral artery.

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Lignin utilization in value-added co-products is an important component of enabling cellulosic biorefinery economics. However, aqueous dilute acid pretreatments yield lignins with limited applications due to significant modification during pretreatment, low solubility in many solvents, and high content of impurities (ash, insoluble polysaccharides). This work addresses these challenges and investigates the extraction and recovery of lignins from lignin-rich insoluble residue following dilute acid pretreatment and enzymatic hydrolysis of corn stover using three extraction approaches: ethanol organosolv, NaOH, and an ionic liquid.

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Corn stover was subjected to dilute sulfuric acid pretreatment to assess the impact of pretreatment conditions on lignin extractability, properties, and utility as a phenol replacement in wood phenol-formaldehyde (PF) adhesives. It was identified that both formic acid and NaOH could extract and recover 60-70% of the lignin remaining after pretreatment and enzymatic hydrolysis under the mildest pretreatment conditions while simultaneously achieving reasonable enzymatic hydrolysis yields (>60%). The availability of reaction sites for the incorporation of lignins into the PF polymer matrix (i.

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 Pancreaticoduodenenctomy is a complex surgery and the sequence of steps is affected by anatomical variations involving small intestine and major vascular structures. This article depicts our approach to two such cases and highlights the importance of identifying these variations preoperatively on imaging, so as to modify the surgery plan accordingly.  We report following two cases of pancreatic head adenocarcinoma (1) one with incomplete intestinal rotation with a replaced right hepatic artery and (2) one with intestinal nonrotation.

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The impact of catalyst choice and reaction conditions during catalytic hydrogenolysis of silver birch biomass are assessed for their effect on aromatic monomer yields and selectivities, lignin removal, and sugar yields from enzymatic hydrolysis. At a reaction temperature of 220 °C with no supplemental H, it was demonstrated that both Co/C and Ni/C exhibited aromatic monomer yields of >50%, which were close to the theoretical maximum expected for the lignin based on total β-O-4 content and exhibited high selectivities for 4-propylguaiacol and 4-propylsyringol. Pd/C exhibited a significantly different set of products, and using a model lignin dimer, showed a product profile that shifted upon inclusion of supplemental H, suggesting that the generation of surface hydrogen is critical for this catalyst system.

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Prior work has identified that lignins recovered from dilute acid-pretreated corn stover exhibit superior performance in phenol-formaldehyde resins used in wood adhesive applications when compared to diverse process-modified lignins derived from other sources. This improved performance is hypothesized to be due to the higher content of unsubstituted phenolic groups specifically p-coumarate lignin esters. In this work, a diverse set of corn stover samples are employed that exhibit diversity in p-coumarate content and total lignin content to explore the relationship between dilute acid pretreatment conditions, p-coumarate ester hydrolysis, xylan solubilization, and the resulting glucose enzymatic hydrolysis yields.

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Background: In this work, three pretreatments under investigation at the DOE Bioenergy Research Centers (BRCs) were subjected to a side-by-side comparison to assess their performance on model bioenergy hardwoods (a eucalyptus and a hybrid poplar). These include co-solvent-enhanced lignocellulosic fractionation (CELF), pretreatment with an ionic liquid using potentially biomass-derived components (cholinium lysinate or [Ch][Lys]), and two-stage Cu-catalyzed alkaline hydrogen peroxide pretreatment (Cu-AHP). For each of the feedstocks, the pretreatments were assessed for their impact on lignin and xylan solubilization and enzymatic hydrolysis yields as a function of enzyme loading.

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Polyurethane chemistry can yield diverse sets of polymeric materials exhibiting a wide range of properties for various applications and market segments. Utilizing lignin as a polyol presents an opportunity to incorporate a currently underutilized renewable aromatic polymer into these products. In this work, we will review the current state of technology for utilizing lignin as a polyol replacement in different polyurethane products.

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Ionic liquids (ILs), are considered as eco-friendly solvents due to their low vapor pressure and non-volatile properties compared to organic solvents and can be employed during processes for the extraction and/or conversion of lignin and chitin to value-added products which can improve the overall economics of the integrated biorefinery concept. However, relatively few studies have investigated their ability to solubilize and modify during solvation of lignin and chitin in terms of crystallinity, molecular weight, etc., with a significant focus on polysaccharides like cellulose and hemicellulose.

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Engineering biomass into functional nanomaterials is captivating. The limitation of versatility in green precursors is pursued by exploring the formation of carbon dots with respect to the contents of the green precursor, . The intermediates formed at different intervals are analyzed.

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Rheumatic heart disease (RHD) is a major cause of cardiovascular morbidity and mortality in developing nations like India. RHD commonly affects the mitral valve which is lined by a single layer of endothelial cells (ECs). The role of ECs in mitral valve damage during RHD is not well elucidated.

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The aim of this work was to study the difference in properties of lignins, those (organosolv lignins (ORGLs, 12±3% yield and 93±5% mass balance) were isolated from diverse rice husk (RH) substrates using organosolv procedure (water:ethanol, HSO) carried out at 180°C for 1h. To identify the possible alterations in lignin structures several bulk and molecular level advanced characterization tools were employed. Even though lignins were extracted using common isolation procedure from three varieties of similar species of RH; from XRD, GPC, and elemental analysis it was found that those have comparable properties on bulk level.

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the causative agent of human tuberculosis, has two proteins belonging to the truncated hemoglobin (trHb) family. Mt-trHbN presents well-defined internal hydrophobic tunnels that allow O and NO to migrate easily from the solvent to the active site, whereas Mt-trHbO possesses tunnels interrupted by a few bulky residues, particularly a tryptophan at position G8. Differential ligand migration rates allow Mt-trHbN to detoxify NO, a crucial step for pathogen survival once under attack by the immune system, much more efficiently than Mt-trHbO.

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Background/aims: The MPS 9000 uses a psychophysical technique known as heterochromatic flicker photometry to measure macular pigment optical density (MPOD). Our aim was to determine the measurement variability (noise) of the MPS 9000.

Methods: Forty normally sighted participants who ranged in age from 18 to 50 years (25.

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Introduction: Though physeal injuries are common in children, concomitant multiple closed contiguous physeal injuries in a limb along with vascular compromise are rare. An associated distractional-separation type of physeal injury is being documented for the first time. We present here two such cases.

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