3D Raman mapping as an analytical tool for investigating the coatings of coated drug particles

The properties of dry-coated paracetamol particles(fast-dissolving model drug)with carnauba wax particles as the coating agent(dissolution retardant)were investigated.Raman mapping technique was used to non-destructively examine the thickness and homogeneity of coated particles.The results showed that the wax existed in two forms on the surface of the paracetamol particles,forming a porous coating layer:i)whole wax particles on the surface of paracetamol and glued together with other wax surface particles,and ii)deformed wax particles spread on the surface.Regardless of the final particle size fraction(between 100 and 800 mm),the coating thickness had high variability,with average thickness of 5.9±4.2 mm.The ability of carnauba wax to decrease the dissolution rate of paracetamol was confirmed by dissolution of powder and tablet formulations.The dissolution was slower for larger coated particles.Tableting further reduced the dissolution rate,clearly indicating the impact of subsequent formulation processes on the final quality of the product.

Coating of bioactive glass on magnesium alloys to improve its degradation behavior: Interfacial aspects

The preferable mechanical properties of Mg alloys along with excellent compatibility with human bone have established their applicability as implant biomaterials.However,a higher corrosion/degradation rate of Mg alloys in body fluids limits its biomedical applications.In this direction,surface modification and coating are explored as appropriate strategies to mode the degradation rate of Mg alloys.The constituents of bioactive glass(BG)provide strength,bio-inertness and bone bonding capability.Hence,researchers have explored the coating of BG on Mg alloys and investigated chemical,mechanical and biological properties of the coated alloys.In this review,we have made an attempt to compile the literature works done on the coating of BG on Mg alloys and its features.Underlying interfacial aspects of the coated substrates towards the degradation behavior are highlighted.The way forward to further improve the coating characteristics of BG coated Mg alloys are remarked.

Thick tongue coating: diagnostic markers for metastatic colorectal cancer?

Background:According to World Health Organization,colorectal cancer is the third most common cancer in the world.The prognosis assessment and condition judgment of the colorectal cancer remains a challenge clinically.Therefore,identification of diagnostic markers to evaluate the prognosis of colorectal cancer clinically should be urgently developed.We have observed that a lot of cancer patients had thick tongue clinically,but what is the relationship between tongue coating and the tumor?Methods:Seventy-four patients with colorectal carcinoma were collected through the outpatients of Tianjin Medical University Cancer Institute and Hospital from May 2010 to September 2011,in which there were 49 patients confirmed with recurrence or metastasis.All photos of patients’tongue were taken with a SONY camera in the same room and under constant conditions such as brightness or distance.Regression equation predicting thickness of tongue coating was constructed using binary logistic regression analysis.The optimal cut off of probabilities to diagnosis thick tongue coating was determined by receiver operating curve analysis.χ2 test for paired data and kappa test were used to determine the diagnostic value for recurrence and/or metastasis in colorectal cancer patients.Kolmogorov-Smirnov test was used to determine the distribution of ALT,AST,ALP ALB,TP,GLO,TBIL,DBIL,GGT,LDH,GLU,UA,CA724,CA199,CA242 and CEA.Data with the skewed distribution were presented as median(quartile interval).The association between the thickness of tongue coating and clinical-pathological character was evaluated by chi square test and two-independent-sample test.The two-independent-samplesχ2 was used to determine whether there were significant differences in the thin coating and thick coating between patients with recurrence and/or metastasis and patients without recurrence and/or metastasis.Kaplan-Meier method was used to analyze survival time.Statistical analysis was performed by SPSS(version 16.0).Results:Through retrospective clinical study we found that overall survival of colorectal cancer patients with thick greasy tongue coating is less than the patients with less tongue coating.What’s more,the risk for recurrence or/and metastasis overall survival in thick coating group was higher than thin coating group.In addition,the histological staining of the tongue slices of rats showed that EGFR receptors in the tongue root were the most among whole tongue surface.Tongue thick coating may be due to tumor patients with high levels of serum EGF which results in significantly increasing tongue coating.This finding suggested that the tongue coating of cancer patients may reflect the level of serum EGF levels in patients which may be related to shorter survival time.In addition,another study showed that serum lactic dehydrogenase level in patients with thick tongue coating is higher than patients with thin tongue coating.Conclusions:These studies suggest that tongue coating is likely to reflect some of the growth factor and enzyme levels.By observing the tongue coating we could predict the prognosis of patients and the characteristics of tongue coating may be used as new diagnostic markers to patients with colorectal carcinoma.

Influence of resin flow on shrinkage of additive manufacturing coated sand molds

Coated sands are used extensively for additive manufacturing sand molds in the metal casting process, and the packing structure changes caused by the resin flow promote the shrinkage and deformation of the part. During the coated sand heating, the resin on the surface flowing to the contact points of the particles forms the resin neck and causes particles to pack close to each other. In this work, the diameters of the coated ceramsite sand before and after heating were measured based on in-situ experimental observations with image measuring apparatus and blue laser, to obtain the relationship between resin coating thickness and the particle diameter. The particle packing model was established to describe the particles' achievement of a stable state one by one. A re-packing simulation was then performed after reducing the particle diameter according to the resin coating thickness, to obtain the shrinkage ratios at different particle size distributions. It was found that the resin coating thickness increased from 0.8 to 2.3 μm as the particle diameter increased from 107 to 500 μm, for the coated ceramsite sand with the resin content of 2 wt.%; the shrinkage ratio decreased first and then increased as the particle diameter increased. The experimental minimum shrinkage ratio was 3.28%, and the corresponding particle diameter was 300-375 μm, while the minimum shrinkage ratio obtained by simulation was 3.43%, and the corresponding particle diameter was 214-300 μm. After mixing the five groups proportionally, the shrinkage ratios of the simulation and experiment dropped to 2.81% and 3.04%, respectively, indicating the best results.

Coating behavior and surface hardening of Pd_(77)Cu_6Si_(17) thin film metallic glass on AZ31 magnesium alloy

Pd77Cu6Si17(PCS) thin film metallic glasses(TFMGs) with high glass forming ability and hardness were selected as a hard coating for improving the surface hardness of AZ31 magnesium alloy. Both microindentation and nanoindentation tests were conducted on specimens with various PCS film thicknesses from 30 to 2000 nm. The apparent hardness and the relative indentation depth(β) were integrated using a quantitative model. The interaction parameters involved and relative hardness values were extracted from iterative calculations. According to the results, surface hardness can be enhanced greatly by PCS TFMGs in the shallow region, followed by gradual decrease with increasing β ratio. In addition, specimens with thinner coatings(e.g., 200nm) showed greater substrate-film interaction and those with thick coatings(e.g., 2000nm) became prone to film cracking. The optimum TFMG coating thickness in this study was estimated to be around 200 nm.

A Model of Spray Tool and a Parameter Optimization Method for Spraying Path Planning

The digital camouflage spraying of special vehicles carried out by robots can greatly improve the spraying efficiency, spraying quality, and rapid adaptability to personalized patterns. The selection of spray tool and the accuracy of the adopted mathematical spray tool model has a great impact on the effectiveness of spray path planning and spraying quality. Since traditional conical spray tool models are not suitable for spraying rectangular digital camouflage, according to the characteristics of digital camouflage, the coating thickness cumulative distribution model of strip nozzle spray tool for 2 D plane spraying and 3 D surface spraying is derived, and its validity is verified by simulation. Based on the accumulation velocity model of the coating thickness(AVCT) on the curved surface and aiming at spraying path planning within the same surface and different surfaces, a path parameter optimization method based on coating uniformity evaluation of adjacent path overlapping area is proposed. Combined with the vehicle surface model, parameters such as path interval, spray tool angle and spray tool motion velocity can be calculated in real-time to ensure uniform coating. Based on the known local three-dimensional model of vehicle surface and the comprehensive spraying simulation, the validity of the purposed models: the coating thickness on the adjacent path area(CTAPA), the coating thickness on the intersection of two surfaces(CTITS), the coating thickness on the intersection of a plane and a surface(CTIPS), and the optimization method of path parameters are verified. The results show that compared with the traditional spray tool, the strip nozzle can better ensure the uniformity of the coating thickness of digital camouflage spray. Finally, according to a practical spraying experiment, the results prove that the proposed models not only are effective but also meet the practical industrial requirements and are of great practical value.