Preventing Cross-Contamination during Lyophilization: GMP and Occupational Cleaning Requirements for Nonproduct and Indirect Product-Contact Parts.

A detailed overview is provided for the possible patient exposure to highly potent active pharmaceutical ingredients (HPAPIs) from potential cross-contamination through the lyophilization process. The intent of this paper is to raise awareness of the risk(s) to patients and stimulate the implementation of adequate risk-based controls, such as containment process(es), use of adequate surrogates in cleaning validation/verification, and test method-sensitivity-based cleaning validation acceptance conditions. Although lyophilizers are considered to be nonproduct-contact surfaces because their surfaces and fixtures do not usually come into direct contact with the product, product contamination can occur at critical locations within a lyophilizer and/or during the unloading process.

Probing optical excitations in chevron-like armchair graphene nanoribbons.

The bottom-up fabrication of graphene nanoribbons (GNRs) has opened new opportunities to specifically tune their electronic and optical properties by precisely controlling their atomic structure. Here, we address excitation in GNRs with periodic structural wiggles, the so-called chevron GNRs. Based on reflectance difference and high-resolution electron energy loss spectroscopies together with ab initio simulations, we demonstrate that their excited-state properties are of excitonic nature.

Exciton-dominated optical response of ultra-narrow graphene nanoribbons.

Narrow graphene nanoribbons exhibit substantial electronic bandgaps and optical properties fundamentally different from those of graphene. Unlike graphene--which shows a wavelength-independent absorbance for visible light--the electronic bandgap, and therefore the optical response, of graphene nanoribbons changes with ribbon width. Here we report on the optical properties of armchair graphene nanoribbons of width N=7 grown on metal surfaces.

Layer resolved evolution of the optical properties of α-sexithiophene thin films.

We report a combined reflectance difference spectroscopy and scanning tunneling microscopy study of ultrathin α-sexithiophene (6T) films deposited on the Cu(110)-(2×1)O surface. The correlation between the layer resolved crystalline structure and the corresponding optical spectra data reveals a highly sensitive dependence of the excitonic optical properties on the layer thickness and crystalline structure of the 6T film.

Stranski-Krastanov growth of para-sexiphenyl on Cu(110)-(2×1)O revealed by optical spectroscopy.

We have studied the growth of para-sexiphenyl (p-6P) on the Cu(110)-(2×1)O surface using reflectance difference spectroscopy (RDS) in combination with scanning tunneling microscopy (STM). The evolution of the optical anisotropy reveals that the growth of p-6P on the Cu(110)-(2×1)O surface at room temperature follows the Stranski-Krastanov growth mode with a two monolayer thick wetting layer. During all stages of growth, the p-6P molecules are well orientated with their long molecular axis aligned parallel to the Cu-O rows along the [001] direction of the Cu(110) substrate.