Surface Treatment of Glass Vials for Lyophilization: Implications for Vacuum-Induced Surface Freezing

Freeze-drying is commonly used to increase the shelf-life of pharmaceuticals and biopharmaceuticals. Freezing represents a crucial phase in the freeze-drying process, as it determines both cycle efficiency and product quality. For this reason, different strategies have been developed to allow for a better control of freezing, among them, the so-called vacuum-induced surface freezing (VISF), which makes it possible to trigger nucleation at the same time in all the vials being processed. We studied the effect of different vial types, characterized by the presence of hydrophilic (sulfate treatment) or hydrophobic (siliconization and TopLyo Si–O–C–H layer) inner coatings, on the application of VISF. We observed that hydrophobic coatings promoted boiling and blow-up phenomena, resulting in unacceptable aesthetic defects in the final product. In contrast, hydrophilic coatings increased the risk of fogging (i.e., the undesired creeping of the product upward along the inner vial surface). We also found that the addition of a surfactant (Tween 80) to the formulation suppressed boiling in hydrophobic-coated vials, but it enhanced the formation of bubbles. This undesired bubbling events induced by the surfactant could, however, be eliminated by a degassing step prior to the application of VISF. Overall, the combination of degasification and surfactant addition seems to be a promising strategy for the successful induction of nucleation by VISF in hydrophobic vials.

Influence of Different Pretreatments on Hot air and Microwave-Hot Air Combined Drying of White Sweet Cherry

Microwave (MW)-hot air (HA) combined drying was applied to white sweet cherries besides solely HA drying at 50, 60 and 70°C in the presence of citric acid, sucrose and freezing pretreatment in this study. Single power level of MW (90 W) was chosen, and drying behavior of all samples was modelled by using eleven thin layer equations. Two-term, rational and sigmoid models were the most suitable models for describing drying phenomena. Effective moisture diffusivities (Deff) ranged from 1.724×10-10 to 5.173×10-10 m2/s in HA drying and from 4.260×10-10 to 1.805×10-9 m2/s in MW-HA drying. Activation energies (Ea) were between 2.785 and 30.541 kJ/mol and 6.929 and 42.101 kJ/mol for HA and MW-HA drying techniques, respectively. Total color change (ΔE) levels of the outer surface of dried cherries were generally higher than the ones of inner surface. Freezing pretreatment had a comparably lower enhancing effect on the total phenolic content (TPC) of HA dried white sweet cherries compared to fresh sample. The TPC of freezing pretreated and HA dried at 50°C and HA dried at 70°C control samples were 1.481 ± 0.398 mg gallic acid equivalent (GAE)/g dry matter (DM) and 6.181 ± 0.012 mg GAE/g DM as the minimum and maximum, respectively. These values were determined as 4.183 ± 1.728 and 8.240 ± 0.502 mg GAE/g DM that were belonged to MW-HA dried at 50°C control and freezing pretreated MW-HA dried at 70°C samples in combined procedure, respectively.

Preparation and Properties of Formic Acid Intercalated Mg-Al Layered Double Hydroxides Deicing Additive

Formic acid intercalated Mg-Al layered double hydroxide (Mg-Al Fo-LDH) was prepared by calcination reduction intercalation assembly technology. The structure of the deicing additive was characterized by fourier transform infrared (FTIR) and X-ray diffraction (XRD). The freezing point of aqueous solution with different quality of deicing additive and the surface freezing point and adhesion of asphalt mixture were tested. The results show that formic acid ion has been intercalated into the interlayer of Mg-Al layered double hydroxide by FTIR and XRD patterns. The freezing point of 5wt% Mg-Al Fo-LDH aqueous solution reaches -9.32 °C, while the surface freezing point of the asphalt mixture mixed with 5wt% Mg-Al Fo-LDH is -6.5°C. At -8 °C, the adhesion force of the surface ice layer is 78.4N, and after the asphalt mixture is soaked in water, the surface freezing point and adhesion force of the ice layer do not change.

Supercooled Southern Ocean Waters

<p>In cold polar waters, temperatures sometimes drop below the freezing point, a process referred to as supercooling. However, observational challenges in polar regions limit our understanding of the spatial and temporal extent of this phenomenon. We here provide observational evidence that supercooled waters are much more widespread in the seasonally ice-covered Southern Ocean than previously reported. In 5.8% of all analyzed hydrographic profiles south of 55° S, we find temperatures below the surface freezing point (‘potential’ supercooling), and half of these have temperatures below the local freezing point (‘in-situ’ supercooling). Their occurrence doubles when neglecting measurement uncertainties. We attribute deep coastal-ocean supercooling to melting of Antarctic ice shelves, and surface-induced supercooling in the seasonal sea-ice region to winter-time sea-ice formation. The latter supercooling type can extend down to the permanent pycnocline due to convective sinking plumes—an important mechanism for vertical tracer transport and water-mass structure in the polar ocean.</p>

Influence of air temperature on a landslide some hundred meters a.s.l.

<p>Displacement development of slopes is influenced by many internal (e.g. strength alteration due to deformation) and external (e.g. precipitation) factors. The combination of these factors is mostly unique, so derivation of universal performance rules is difficult, and landslides mostly are individua. The contribution describes a landslide in Flysch, most probably reactivated by exceptional rainfalls as well as by works for the renewal of a weir in the valley bottom in 2009. Monitoring showed that the landslide just some hundred meters a.s.l. moves more rapidly during wintertime caused by reduced evapotranspiration as well as by slope surface freezing both leading to groundwater impounding and, therefore, acceleration of displacements. Thus, it behaves completely different from landslides in higher altitudes, which are influenced predominantly by snowmelt causing larger displacements during late spring and summer.</p>

Controlling Ice Nucleation during Lyophilization: Process Optimization of Vacuum-Induced Surface Freezing

Biopharmaceuticals are often lyophilized to improve their storage stability. Controlling ice nucleation during the freezing step of the lyophilization process is desired to increase homogeneity of product properties across a drug product batch and shorten the primary drying time. The present communication summarizes the process optimization of the freezing process when using vacuum-induced surface freezing to control ice nucleation, in particular for amorphous samples. We characterized freeze-dried samples for solid state properties, and compared these to uncontrolled nucleated samples using bovine serum albumin (BSA) as a model protein. Freezing parameters were optimized to obtain complete nucleation, adequate cake resistance during the subsequent lyophilization cycle, and elegant cakes. We highlight the challenges associated with vacuum-induced surface freezing and propose optimized freezing parameters to control ice nucleation, enabling manufacturing of amorphous samples.