Current and future trends of additive manufacturing for chemistry applications: a review

Three-dimensional (3-D) printing, also known as additive manufacturing, refers to a method used to generate a physical object by joining materials in a layer-by-layer process from a three-dimensional virtual model. 3-D printing technology has been traditionally employed in rapid prototyping, engineering, and industrial design. More recently, new applications continue to emerge; this is because of its exceptional advantage and flexibility over the traditional manufacturing process. Unlike other conventional manufacturing methods, which are fundamentally subtractive, 3-D printing is additive and, therefore, produces less waste. This review comprehensively summarises the application of additive manufacturing technologies in chemistry, chemical synthesis, and catalysis with particular attention to the production of general laboratory hardware, analytical facilities, reaction devices, and catalytically active substances. It also focuses on new and upcoming applications such as digital chemical synthesis, automation, and robotics in a synthetic environment. While discussing the contribution of this research area in the last decade, the current, future, and economic opportunities of additive manufacturing in chemical research and material development were fully covered.

Graphical abstract

     

LCA of second generation bioethanol: A review and some issues to be resolved for good LCA practice

This paper aims at reviewing the life cycle assessment (LCA) literature on second generation bioethanol based on lignocellulosic biomass and at identifying issues to be resolved for good LCA practice. Reviews are carried out on respective LCA studies published over the last six years. We use the classification of lignocellulosic biomass to define system boundaries, so that the comparison among LCA results can be thoroughly assessed based on identified system components. A basis for attributing environmental burden for different biomass feedstocks is also suggested. Despite the non-homogeneous systems, we conclude that second generation bioethanol performs better than fossil fuel at least for the two most studied impact categories, net energy output and global warming. For the latter category, carbon sequestration at the biomass generation stage can even consistently offset the GHG emissions from all parts of the life cycle chains at high ethanol percentage (≥85%). The aspect of biogenic carbon and agrochemical input for energy crops and biomass residues, and the effect of removal of the latter from soil have not been treated consistently. In contrast, the exclusion of upstream chain of biomass waste feedstocks is observed in practice. The bioethanol conversion process is mostly based on simultaneous saccharification and co-fermentation, characterized by high yield and low energy input. In this regard, the LCA results tend to under estimate the real impacts of the current technology. The choice of allocation methods strongly influences the final results, particularly when economic value is used as a reference. Substitution of avoided burden seems to be the most popular allocation method in practice, followed by partition based on mass, energy, and economic values.     

Relocation Counselling and Supportive Services as Tools to Prevent Negative Spillover Effects: A Review

This paper aims to review the literature on negative neighbourhood spillovers connected to four voluntary housing mobility programs: Gautreaux 1 and Gautreaux 2 (Chicago), the Moving to Opportunity Fair Housing Demonstration (five cities) and the Baltimore Housing Mobility Program. Although these four programs involve voluntary moves, a great deal may be learned from them because of (1) efforts to forestall community opposition and (2) special counselling and supportive programs provided to ease adjustment into destination neighbourhoods. Unfortunately, the available research often falls short in providing evidence for or against negative spillover effects. Nevertheless, our review indicates that screening out multi-problem families, limiting the number of housing voucher families moving into particular neighbourhoods and providing both pre- and post-relocation counselling to program participants can minimize the risk of negative neighbourhood spillovers.     

Massive gas embolism following lung inflation for thoracic tomodensitometry in a multiple trauma patient with lung contusions

We report a case of gas embolism into both right and left circulation in a polytrauma patient with lung contusions, revealed by thoracic CT scan showing the heart and aorta filled with gas. It followed a lung inflation with a O2/N2O mixture for about 30 seconds at a pressure of at least 40 cmH2O in order to obtain apnoea for CT scan and to recruit atelectatic territories. The presumed mechanism was the passage of the O2/N2O mixture during the lung inflation manoeuvre out of disrupted airways into torn pulmonary blood vessels and pushed back into the heart chambers. The patient recovered fully. Lung inflation manoeuvre to obtain a prolonged apnoea during CT scan examinations of thorax is contraindicated in case of thorax trauma, as it carries a risk of gas embolism.     

Spearmints: hardware support for performance measurements indistributed systems

Spearmints, a system of hardware components that can be easily interfaced to the nodes of an instrumented distributed system for monitoring or evaluation using event-triggered measurements, is described. Each machine of the target system must have one sensor that collects relevant events and marks them with global time stamps. The sensors can be attached to a common measurement system that samples the marked events on- or offline, orders them chronologically, and analyzes the resulting sequence. The design of Spearmints is based on providing a simple and universal tool that causes little interference and furnishes highly accurate measurements in distributed systems. As Spearmints only requires standard interfaces with its integration into an object system and its connection to a measurement system, it permits the use of a wide range of measurement systems for the evaluation of a variety of distributed systems     

Improved Optical Setup to Measure Growth and Megting of Solid 3He Below 1 mK in Magnetic Fields Up to 9 Tesla

Recent experiments on crystal growth and crystal shape in ³He at zero magnetic field at 0.55 mK by Tsepelin et al. ^{1, 2} in Helsinki have revealed many new facets and strong anisotropy in the growth rates. Since ³He presents the unique possibility of investigating the influence of a magnetic field on crystal growth properties, we intend to extend our experimental studies of the shape and growth rate of solid ³He to magnetic fields up to 9 T at temperatures as low as possible.For that purpose our optical access cryostat with low temperature CCD has been upgraded and modified. The low temperature LED is replaced by a room temperature source coupled to the cell with an optical fiber to obtain clear images of the growth process. Our Pomeranchuk cell has been fitted with a new optical section with pure quartz windows. It has a larger diameter, a larger distance between the optical windows, and an improved thermal link. Also the heat switches between the nuclear stage and the dilution refrigerator were replaced according to a more sturdy design. Initial resugts show clear crystals with sharp facet edges down to T=0.4 mK.     

Preparation and physicochemical evaluation of a new tacrolimus tablet formulation for sublingual administration

The aim of this study was to develop a new fast-disintegrating tablet formulation containing 1?mg tacrolimus for sublingual application. First, solid dispersions containing tacrolimus (2.5%, 5% and 10% w/w) incorporated in Ac-Di-Sol(?) and carriers (inulin 1.8?kDa and 4?kDa, and polyvinylpyrrolidone (PVP) K30) were prepared by freeze drying. Subsequently, a tablet formulation composed of a mixture of the solid dispersions, Ac-Di-Sol(?), mannitol, Avicel(?) PH-101 and sodium stearyl fumarate was optimized concerning drug load in the solid dispersions and the type of carrier. Tablet weight was kept constant at 75?mg by adjusting the amount of Avicel(?) PH-101. Differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD) results indicated the absence of the drug in the crystalline state, which was confirmed by the scanning electron microscopy (SEM). These results suggest that tacrolimus incorporated in all of the solid dispersions was fully amorphous. Dissolution of the tablets containing solid dispersions with a low drug load highly depends on the type of carrier and increased in the order: PVP K30 < inulin 4?kDa < inulin 1.8?kDa. Solid dispersions with a drug load of 10% w/w incorporated in the carriers yielded optimal formulations. In addition, the physicochemical characteristics and the dissolution behavior of the tablet formulation containing inulin 1.8 kDa-based solid dispersions with a drug load of 10% w/w did not change after storage at 20°C/45%RH for 6 months indicating excellent storage stability.     

pH-independent immediate release polymethacrylate formulations – an observational study

Abstract

Using Eudragit® E PO (EudrE) as a polymethacrylate carrier, the aim of the study was to develop a pH-independent dosage form containing ibuprofen (IBP) as an active compound via chemical modification of the polymer (i.e. quaternization of amine function) or via the addition of dicarboxylic acids (succinic, glutaric and adipic acid) to create a pH micro-environment during dissolution. Biconvex tablets (diameter: 10?mm; height: 5?mm) were produced via hot melt extrusion and injection molding. In vitro dissolution experiments revealed that a minimum of 25% of quaternization was sufficient to partially (up to pH 5) eliminate the pH-dependent effect of the EudrE/IBP formulation. The addition of dicarboxylic acids did not alter IBP release in a pH 1 and 3 medium as the dimethyl amino groups of EudrE are already fully protonated, while in a pH 5 solvent IBP release was significantly improved (cf. from 0% to 92% release after 1?h dissolution experiments upon the addition of 20?wt.% succinic acid). Hence, both approaches resulted in a pH-independent (up to pH 5) immediate release formulation. However, the presence of a positively charged polymer induced stability issues (recrystallization of API) and the formulations containing dicarboxylic acids were classified as mechanically unstable. Hence, further research is needed to obtain a pH-independent immediate release formulation while using EudrE as a polmethacrylate carrier.     

Catalyst Deactivation Rate During Hydrogenation of CO2 to Longer-Chained Hydrocarbons Over 6 wt% Potassium-Promoted Co/Al2O3 Catalyst

Catalysis Letters - The deactivation rate of 15%Co-6%K/Al2O3 Fischer–Tropsch catalyst during hydrogenation of CO2 to longer-chained hydrocarbons was investigated. The catalysts used were...     

Development of lignin carbon fibers: Evaluation of the carbonization process

The use of lignin as a renewable resource for the production of less‐expensive carbon fibers has in recent years attracted great interest. In order to develop the strength properties, the stabilization and carbonization processes have to be optimized. For this reason, the process parameters during carbonization have here been studied on stabilized lignin fibers in the temperature interval from 300 to 1300 °C. The effects of temperature, heating rate, and straining of fibers during carbonization on the strength properties of carbon fibers were investigated. The heating rate, in the range from 1 to 40 °C/min, was shown to have no effect on the property development of the fibers. During carbonization with no load applied to the fibers, a shrinkage of 20% was noted. Counteracting the shrinkage by imposing a load on the fibers during the carbonization resulted in fibers with a greater stiffness. The tensile strength was not, however, affected by this loading. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43965.