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A series of Zr incorporated small crystal size Y zeolites were successfully synthesized by a direct hydrothermal method, and the corresponding NiW catalysts were prepared for the hydrocracking of vacuum gas oil (VGO). The synthesized zeolites and prepared catalysts were characterized by XRD, SEM, FTIR, Pyridine FTIR, H2-TPR and TEM techniques. The results show that the synthesized zeolites have uniform morphology and small crystal size, while Zr4+ incorporated into the framework of Y zeolite has been confirmed by XRD and FTIR. The amount of acid sites of xZrY zeolite slightly increases compared with that of Y zeolite by Pyridine FTIR. Moreover, the Zr4+ incorporation into Y zeolite can increase the W species reducibility, modulate the length and stacking of WS2 phase, and enhance the W species dispersion on the catalyst surface by H2-TPR and TEM, which favor to improve the hydrogenation activity of the catalyst to tune the balance between cracking activity and hydrogenation/dehydrogenation activity. Hence, the catalyst containing xZrY zeolite exhibits not only higher yield and selectivity of middle distillate but also slightly higher conversion of VGO compared with the catalyst containing Y zeolite.

This study examined the post-thaw recovery of Jurkat cells cryopreserved in three combinations of five osmolytes including trehalose, sucrose, glycerol, mannitol, and creatine. Cellular response was characterized using low-temperature Raman spectroscopy, and variation of post-thaw recovery was analyzed using statistical modeling. Combinations of osmolytes displayed distinct trends of post-thaw recovery, and a nonlinear relationship between compositions and post-thaw recovery was observed, suggesting interactions not only between different solutes but also between solutes and cells. The post-thaw recovery for optimized cryoprotectants in different combinations of osmolytes at a cooling rate of 1°C/min was comparable to that measured with 10% dimethyl sulfoxide. Statistical modeling was used to understand the importance of individual osmolytes as well as interactions between osmolytes on post-thaw recovery. Both higher concentrations of glycerol and certain interactions between sugars and glycerol were found to typically increase the post-thaw recovery. Raman images showed the influence of osmolytes and combinations of osmolytes on ice crystal shape, which reflected the interactions between osmolytes and water. Differences in the composition also influenced the presence or absence of intracellular ice formation, which could also be detected by Raman. These studies help us understand the modes of action for cryoprotective agents in these osmolyte solutions.

There is considerable interest in the use of sugars to preserve cells. In this study, low temperature Raman spectroscopy was used to characterize the behaviors of sucrose during freezing. The hydrogen bond network between sucrose and water was investigated at -10 °C and -50 °C, and the Raman spectra showed strengthened sucrose-water and sucrose-sucrose hydrogen bonds in more concentrated sucrose solution at -50 °C. The concentration of sucrose at the ice interface increased as the ice density decreased, and it plateaued across a narrow channel of nonfrozen sucrose solution before it decreased toward the next ice interface. The biophysical environment at interfaces between the cell and nonfrozen sucrose solution and between the cell and extracellular ice was also studied. A thin layer of nonfrozen sucrose solution was observed at the interface between the cell and extracellular ice. The extracellular concentration of sucrose at this interface was generally lower than that of bulk nonfrozen sucrose solution. The variation of sucrose concentration outside different regions of the cell membrane suggests that the chemical environment around the cell during freezing may be more heterogeneous than previously thought. Raman spectra and images also showed colocalization of nonfrozen sucrose solution and the cell, which implied that direct interaction between sucrose and cell membrane might be responsible for protective properties of sucrose. Sucrose was predominantly distributed outside the cell, and the observation of strong partitioning of sucrose across the cell membrane is consistent with substantial cell dehydration detected by the Raman spectra. This work enhances our understanding of the behaviors of sucrose solution and its interactions with cells at low temperature and can improve cryopreservation protocols of cells frozen in a sucrose-based media.

Inadequate preservation methods of human induced pluripotent stem cells (hiPSCs) have impeded efficient reestablishment of cell culture after the freeze–thaw process. In this study, we examined roles of the cooling rate, seeding temperature, and difference between cell aggregates (3–50 cells) and single cells in controlled rate freezing of hiPSCs. Intracellular ice formation (IIF), post-thaw membrane integrity, cell attachment, apoptosis, and cytoskeleton organization were evaluated to understand the different freezing responses between hiPSC single cells and aggregates, among cooling rates of 1, 3, and 10°C/min, and between seeding temperatures of −4°C and −8°C. Raman spectroscopy images of ice showed that a lower seeding temperature (−8°C) did not affect IIF in single cells, but significantly increased IIF in aggregates, suggesting higher sensitivity of aggregates to supercooling. In the absence of IIF, Raman images showed greater variation of dimethyl sulfoxide concentration across aggregates than single cells, suggesting cryoprotectant transport limitations in aggregates. The ability of cryopreserved aggregates to attach to culture substrates did not correlate with membrane integrity for the wide range of freezing parameters, indicating inadequacy of using only membrane integrity-based optimization metrics. Lower cooling rates (1 and 3°C/min) combined with higher seeding temperature (−4°C) were better at preventing IIF and preserving cell function than a higher cooling rate (10°C/min) or lower seeding temperature (−8°C), proving the seeding temperature range of −7°C to −12°C from literature to be suboptimal. Unique f-actin cytoskeletal organization into a honeycomb-like pattern was observed in postpassage and post-thaw colonies and correlated with successful reestablishment of cell culture.

In the unique supply chain of cellular therapies, preservation is important to keep the cell product viable. Many factors in cryopreservation affect the outcome of a cell therapy: (i) formulation and introduction of a freezing medium, (ii) cooling rate, (iii) storage conditions, (iv) thawing conditions and (v) post-thaw processing. This article surveys clinical trials of cellular immunotherapy that used cryopreserved regulatory, chimeric antigen receptor or gamma delta T cells, dendritic cells or natural killer (NK) cells. Several observations are summarized from the given information. The aforementioned cell types have been similarly frozen in media containing 5-10% dimethyl sulfoxide (DMSO) with plasma, serum or human serum albumin. Two common freezing methods are an insulated freezing container such as Nalgene Mr. Frosty and a controlled-rate freezer at a cooling rate of -1°C/min. Water baths at approximately 37°C have been commonly used for thawing. Post-thaw processing of cryopreserved cells varied greatly: some studies infused the cells immediately upon thawing; some diluted the cells in a carrier solution of varying formulation before infusion; some washed cells to remove cryoprotective agents; and others re-cultured cells to recover cell viability or functionality lost due to cryopreservation. Emerging approaches to preserving cellular immunotherapies are also described. DMSO-free formulations of the freezing media have demonstrated improved preservation of cell viability in T lymphocytes and of cytotoxic function in natural killer cells. Saccharides are a common type of molecule used as an alternative cryoprotective agent to DMSO. Improving methods of preservation will be critical to growth in the clinical use of cellular immunotherapies.

This study examined the post-thaw recovery of Jurkat cells cryopreserved in single osmolyte solutions containing sucrose, glycerol or isoleucine, as well as in a combination of the three osmolytes. Cell response was determined using low temperature Raman Spectroscopy and variation in post-thaw recovery with composition was analyzed using statistical modeling. Post-thaw recovery of Jurkat cells in single osmolyte was low. A combination of the osmolytes displayed a non-linear relationship between composition and post-thaw recovery, suggesting that interactions exist between the different solutes. The post-thaw recovery for an optimized multicomponent solution was comparable to that observed using 10% dimethyl sulfoxide and a cooling rate of 1 °C/min. Statistical modeling was used to characterize the importance of each osmolyte in the combination and test for interactions between osmolytes. Higher concentrations of glycerol increase post-thaw recovery and interactions between sucrose and glycerol, as well as sucrose and isoleucine improve post-thaw recovery. Raman images clearly demonstrated that damaging intracellular ice formation was observed more often in the presence of single osmolytes as well as non-optimized multi-component solution compositions.

Three catalysts NiW/Al 2 O 3 , NiW–P/Al 2 O 3 and NiW–CA/Al 2 O 3 with different morphologies but similar pore structures and acidity properties were prepared for studying the effect of morphology properties on the hydrodesulfurization (HDS) activity for individual sulfur compounds in fluid catalytic cracking (FCC) diesel. The morphology properties of the selected catalysts in oxidation and sulfidation states were characterized and the contents of individual sulfur compounds were determined by gas chromatography–pulse flame photometric detector (GC–PFPD). The results showed that NiW–P/Al 2 O 3 possessed the highest edge density of WS 2 phase and NiW–CA/Al 2 O 3 had the highest stacking degree of multilayered WS 2 phase. The HDS assessment showed that NiW–CA/Al 2 O 3 demonstrated positive effects on the HDS of refractory sulfur compounds like 4,6-dimethyldibenzothiophene (4,6-DMDBT) or dibenzothiophene (DBT) with alkyl substitutes containing 3 carbons (C 3 DBT) but slight negative effects on the HDS of simple sulfur compounds such as benzothiophene (BT) with alkyl substitutes containing 1 ~ 5 carbons (C 1 ~ C 5 BT) and DBT with alkyl substitutes containing 1 carbon (C 1 DBT); while NiW–P/Al 2 O 3 favored for the HDS of simple sulfur compounds. The present results indicated that the morphology of WS 2 phase has a great influence on the HDS selectivity for different structured sulfur compounds.

USY zeolites were modified by zirconium, phosphorus and both zirconium and phosphorus, and the corresponding catalysts were prepared for hydrocracking of vacuum gas oil. The results showed that Zr-modified USY enhanced W species dispersion on catalyst surface, weakened interaction of W species with support and improved W species reducibility, leading to formation of highly stacked WS2 slabs and higher sulfidation degree of W species, which was favorable for the enhancement of hydrogenation activity. The influence of the modification with zirconium and phosphorus on these properties of catalyst was more pronounced than that of zirconium or phosphorus modification because of the synergistic action of phosphorus and zirconium. The catalyst containing Zr-USY had slightly lower hydrocracking activity than that containing USY owing to a diminution of acid sites, but presented obviously greater middle distillate selectivity arising from the improvement of hydrogenation activity. The middle distillate selectivity on catalyst containing Zr-P-USY was higher than that on catalysts containing Zr-USY or P-USY, corresponding to its more effective catalyst properties.

There is demand for non-dimethyl sulfoxide (DMSO) cryoprotective agents that maintain cell viability without causing poor postthaw function or systemic toxicity. The focus of this investigation involves expanding our understanding of multicomponent osmolyte solutions and their ability to preserve cell viability during freezing. Controlled cooling rate freezing, Raman microscopy, and differential scanning calorimetry (DSC) were utilized to evaluate the differences in recovery and ice crystal formation behavior for solutions containing multiple cryoprotectants, including sugars, sugar alcohols, and small molecule additives. Postthaw recovery of mesenchymal stem cells (MSCs) in solutions containing multiple osmolytes have been shown to be comparable or better than that of MSCs frozen in 10% DMSO at 1°C/min when the solution composition is optimized. Maximum postthaw recovery was observed in these multiple osmolyte solutions with incubation times of up to 2 h before freezing. Raman images demonstrate large ice crystal formation in cryopreserved cells incubated for shorter periods of time (∼30 min), suggesting that longer permeation times are needed for these solutions. Recovery was dependent upon the concentration of each component in solution, and was not strongly correlated with osmolarity. It is noteworthy that the postthaw recovery varied significantly with the composition of solutions containing the same three components and this variation exhibited an inverted U-shape behavior, indicating that there may be a “sweet spot” for different combinations of osmolytes. Raman images of freezing behavior in different solution compositions were consistent with the observed postthaw recovery. Phase change behavior (solidification patterns and glass-forming tendency) did not differ for solutions with similar osmolarity, but differences in postthaw recovery suggest that biological, not physical, methods of protection are at play. Lastly, molecular substitution of glucose (a monosaccharide) for sucrose (a disaccharide) resulted in a significant drop in recovery. Taken together, the information from these studies increases our understanding of non-DMSO multicomponent cryoprotective solutions and the manner by which they enhance postthaw recovery.

This article presents a novel method for preparing hydrodenitrogenation (HDN) catalysts via combined phosphorous modification of alumina and ethylenediaminetetraacetic acid (EDTA)-assisted dispersion of active metals. The results showed that the catalyst prepared with this method possessed high dispersion of nickel and tungsten species, ascribed to EDTA addition. Simultaneously, high sulfidation degree of tungsten and nickel species was obtained due to the addition of phosphorous and EDTA. So the catalyst prepared by this method exhibited a greatly enhanced hydrodenitrogenation activity than the conventional method prepared.