Heterogeneous Brønsted Catalysis in the Solvent-Free and Multigram-Scale Synthesis of Polyalcohol Acrylates: The Case Study of Trimethylolpropane Triacrylate

This article presents a thorough investigation into the synthesis of trimethylolpropane triacrylate (TMPTA) via the esterification reaction of trimethylolpropane (TMP) with acrylic acid using Amberlite™ 120 IR (H+), Amberlyst® 15, and Dowex™ 50WX8 resins as heterogeneous catalysts. Preliminary comparative tests explored the impact of air flow on water removal during the reaction and different acid-to-alcohol molar ratios (3:1, 6:1, or 9:1 mol:mol). The findings revealed that introducing air significantly enhances TMPTA yield and -OH group conversion, particularly at a 6:1 acid-to-alcohol molar ratio. Based on cost considerations, Amberlite™ 120 IR (H+) was selected as the preferred catalyst for further optimization. This included evaluating the effect of catalyst loading (10%, 5.0%, and 2.5% w/wtot) and assessing the impact of a pre-drying process on resin efficiency. The study concluded that optimal conditions did not necessitate drying, requiring 120 °C, a catalyst loading of 10% w/wtot, a 4 h reaction time, an acid:alcohol ratio of 6:1 mol:mol, the presence of MEHQ (0.1% mol/molAA), and air bubbling at 6 ± 1 Nl/h. Catalyst recycling was effectively implemented with a slight reduction in catalytic activity over consecutive runs. Furthermore, the study explored a scaled-up system with a mechanical stirrer, demonstrating the potential for multi-hundred grams scale-up. Considerations for optimizing the air flow stripping system are also highlighted. In summary, this study provides valuable insights into designing and optimizing the esterification process for TMPTA synthesis, laying the foundation for potential industrial applications.

Widespread Megaripple Activity Across the North Polar Ergs of Mars

The most expansive dune fields on Mars surround the northern polar cap where various aeolian bedform classes are modified by wind and ice. The morphology and dynamics of these ripples, intermediate-scale bedforms (termed megaripples and Transverse Aeolian Ridges [TARs]), and sand dunes reflect information regarding regional boundary conditions. We found that populations of polar megaripples and larger TARs are distinct in terms of their morphology, spatial distribution, and mobility. Whereas regionally restricted TARs appeared degraded and static in long-baseline observations, polar megaripples were not only widespread but migrating at relatively high rates (0.13 ± 0.03 m/Earth year) and possibly more active than other regions on Mars. This high level of activity is somewhat surprising since there is limited seasonality for aeolian transport due to surficial frost and ice during the latter half of the martian year. A comprehensive analysis of an Olympia Cavi dune field estimated that the advancement of megaripples, ripples, and dunes avalanches accounted for ~1%, ~10%, and ~100%, respectively, of the total aeolian system's sand fluxes. This included dark-toned ripples that migrated the average equivalent of 9.6 ± 6 m/yr over just 22 days in northern summer-unprecedented rates for Mars. While bedform transport rates are some of the highest yet reported on Mars, the sand flux contribution between the different bedforms does not substantially vary from equatorial sites with lower rates. Seasonal off-cap sublimation winds and summer-time polar storms are attributed as the cause for the elevated activity, rather than cryospheric processes.

Periodic Bedrock Ridges at the ExoMars 2022 Landing Site: Evidence for a Changing Wind Regime

Wind-formed features are abundant in Oxia Planum (Mars), the landing site of the 2022 ExoMars mission, which shows geological evidence for a past wet environment. Studies of aeolian bedforms at the landing site were focused on assessing the risk for rover trafficability, however their potential in recording climatic fluctuations has not been explored. Here we show that the landing site experienced multiple climatic changes in the Amazonian, which are recorded by an intriguing set of ridges that we interpret as Periodic Bedrock Ridges (PBRs). Clues for a PBR origin result from ridge regularity, defect terminations, and the presence of preserved megaripples detaching from the PBRs. PBR orientation differs from superimposed transverse aeolian ridges pointing toward a major change in wind regime. Our results provide constrains on PBR formation mechanisms and offer indications on paleo winds that will be crucial for understanding the landing site geology.

Megaripple Migration on Mars

Aeolian megaripples, with 5- to 50-m spacing, are abundant on the surface of Mars. These features were repeatedly targeted by high-resolution orbital images, but they have never been observed to move. Thus, aeolian megaripples (especially the bright-toned ones often referred as Transverse Aeolian Ridges-TARs) have been interpreted as relict features of a past climate. In this report, we show evidence for the migration of bright-toned megaripples spaced 1 to 35 m (5 m on average) in two equatorial areas on Mars indicating that megaripples and small TARs can be active today. The moving megaripples display sand fluxes that are 2 orders of magnitudes lower than the surrounding dunes on average and, unlike similar bedforms on Earth, can migrate obliquely and longitudinally. In addition, the active megaripples in the two study areas of Syrtis Major and Mawrth Vallis show very similar flux distributions, echoing the similarities between dune crest fluxes in the two study areas and suggesting the existence of a relationship between dune and megaripple fluxes that can be explored elsewhere. Active megaripples, together with high-sand flux dunes, represent a key indicator of strong winds at the surface of Mars. A past climate with a denser atmosphere is not necessary to explain their accumulation and migration.

Bloodstream infections can develop late (after day 100) and/or in the absence of neutropenia in children receiving allogeneic bone marrow transplantation

We retrospectively evaluated the incidence and time from transplantation of bloodstream infections occurring in children receiving bone marrow transplant (BMT) at G Gaslini Children's Hospital between September 1984 and December 1997. During this period the incidence was 35% after allogeneic and 26% after autologous BMT (P=0.08). Among these episodes, 38% after allogeneic BMT and 90% after autologous BMT were detected in the presence of neutropenia within the first 30 days from reinfusion (P < 0.001). Incidence of catheter-related bloodstream infections was 40% after allogeneic and 8% after autologous BMT (P < 0.001). Bloodstream infections in the absence of neutropenia were 55% after allogeneic BMT vs 10% after autologous BMT (P < 0.001) and occurred later after reinfusion (mean 199 vs 41 days, P <0.001). Among the episodes occurring after allogeneic BMT and in the absence of neutropenia, 61% were related to the presence of a central venous catheter, 15% were related to the presence of GVHD, but 23% were not associated with any of major risk factors for infection. Finally, 38% of episodes following allogeneic BMT were detected after day 100 vs 1% after autologous BMT. We concluded that patients receiving allogeneic BMT experience a high incidence of bloodstream infections in the absence of neutropenia and that a significant proportion of these episodes is not clearly associated with well known risk factors such as GVHD or central venous catheters. Moreover, many episodes develop a long time after the transplantation procedure. Therefore, any febrile episode following allogeneic BMT even late and/or in the absence of neutropenia should be intensively managed.

Topical dimethylsulfoxide for the prevention of soft tissue injury after extravasation of vesicant cytotoxic drugs: a prospective clinical study

PURPOSE

To evaluate the activity and tolerability of dimethylsulfoxide (DMSO) in the prevention of soft tissue toxicity after extravasation of cytotoxic drugs.

PATIENTS AND METHODS

From June 1991 to December 1994, all patients who had an extravasation during intravenous (IV) infusion of cytotoxic drugs in our institution were considered for an open, prospective study of preventive treatment with 99% DMSO, applied topically on the extravasation site every 8 hours for 7 days. Intermittent local cooling (for 1 hour three times daily) on the first 3 days was also used.

RESULTS

One hundred forty-four patients with extravasations of doxorubicin (n = 11), epirubicin (n = 46), mitomycin (n = 5), mitoxantrone (n = 13), cisplatin (n = 44), carboplatin (n = 6), ifosfamide (n = 14), and fluorouracil (n = 5) entered the study; 127 were assessable. Only one patient suffered an ulceration. The treatment was well tolerated, with mild local burning and a characteristic breath odor being the only side effects of DMSO application, even in cases in which treatment continued for up to 6 weeks to obtain remission of the symptoms of extravasation.

CONCLUSION

Topical DMSO is an effective and safe antidote that may be used with local cooling after extravasations of vesicant drugs other than those drugs for which standard interventions are defined.

[Sulodexide in the prevention of post-mastectomy lymphedema]

Post-mastectomy lymphedema of the upper limb, that can be noticed by 10 to 20 percent of patients with breast cancer, is usually related to some risk factors: use of radiotherapy on the axilla, obesity, venous outflow obstruction, delayed wound healing or infection. The most important contributing factor to postsurgical edema is the development of lymphangitis in the upper limb. Although literature contains numerous accounts on the use of pharmacological agents for the treatment of postmastectomy lymphedema, the results are not satisfactory in term of clinical response and side effects. In the present study we investigate tolerability and feasibility of the use of suledexide in patients, submitted to mastectomy for breast cancer, with an initial lymphedema of the limb omolateral to surgery or other risk factors for the development of a clinical remarkable lymphedema. Our results show that sulodexide is a very satisfactory therapy in term of lack of side effects and good compliance.

Combined management in the treatment of epidoxorubicin extravasation. A case report

Inadvertent extravasation during intravenous antitumor therapy is not an unusual complication and can cause damage ranging from minor erythema to severe local necrosis. The appropriate management of these iatrogenic accidents as a part of supportive care in oncology has been addressed by several experimental studies, but there has been little clinical study and no conclusive evidence on the best therapeutic strategies to adopt. The case reported here of a patient suffering from severe soft-tissue injury caused by extravasation of epidoxorubicin demonstrates the usefulness of a combined management (medical, surgical and rehabilitative) in the appropriate care of extravasation.

Hyaluronidase as an antidote to extravasation of Vinca alkaloids: clinical results

Skin necrosis is a recognized potential consequence of an inadvertent extravasation of Vinca alkaloids in the surrounding tissues during i.v. administration. Experimental studies suggest that hyaluronidase, an enzyme that degrades hyaluronic acid and improves the absorption of locally injected drugs, can reduce the risk of progressing to skin necrosis. On this basis, we used this enzyme as a local treatment after extravasations of Vinca alkaloids in seven patients. No patient suffered from subsequent skin necrosis. To the best of our knowledge, this is the first clinical report confirming the positive findings of experimental studies on the effectiveness of this antidote.