Water Absorption Peak Research Articles

Evaluation of cartilage properties from NIR diffuse reflectance spectra: numerical simulation

Diseased conditions of articular cartilage such as osteoarthritis (OA) are accompanied by a change in the water concentration, together with a decrease in cartilage thickness. These parameters are important indicators of the normal joint functioning. Light scattering in a heterogeneous joint tissue is a complex process and it is important to supplement its study with understanding gained from modelling. In this work we employed Monte Carlo for analysis of the relationship between changes in cartilage parameters and calculated diffuse reflectance spectra. It has been shown that water absorption peak at 980 nm is determined by both water content and cartilage thickness, while changes in diffuse reflectance spectra at 1450 nm are mostly driven only by water content. Since independent assessment of these parameters is clinically relevant, several approaches for their determination were developed. A heuristic algorithm for cartilage thickness determination and its quality metrics (R 2 = 0.96) were obtained. Several regression models were developed using the amplitudes of diffuse reflectance spectra at different wavelengths and it was shown that the use of a wide range of wavelengths (850–1700 nm) allows to determine the cartilage water concentration and its thickness with the accuracy R 2 0.96 and 0.99 while measuring at different probe-detector distances.

Development of the 2.7 μm to 3 μm Erbium-Doped Laser

The 3 μm wavelength band laser is located on the strong absorption peak of water and the atmospheric transmission window. The 3 μm laser with high single pulse energy is used in medical treatment for cutting soft tissues and bones during surgery. It is used as a pump source for optical parametric oscillators, and Fe lasers can realize 3~5 μm or 8~14 μm laser output, which has an irreplaceable role in certain areas (e.g., optoelectronic countermeasures, LIDAR, atmospheric monitoring, etc.). Commercial semiconductor-pumped Er lasers are capable of achieving 3 μm laser output of 600 mJ with the maturation of a 970 nm semiconductor laser. The conversion efficiency is significantly improved. However, the energy is lower than a flash-lamp-pumped Er laser. There are still serious crystal thermal effects and an inefficient conversion process. In this paper, the energy-level systems of 3 μm Er-doped lasers are discussed. A summary of the current state of research on Er lasers using different matrices and the commercialization of Er-doped lasers with wavelengths ranging from 2.7 μm to 3 μm is also provided. Several technical means are given to enhance laser performance. Furthermore, the development of Er-doped solid-state lasers with wavelengths between 2.7 and 3 μm is envisaged in the near future.

Preparation of a water‐absorbent mesoporous material and film to simulate the infrared spectrum of plants

AbstractHyperspectral imaging poses great challenges to traditional camouflage materials, primarily because there is a huge difference between the reflectance spectra of camouflage materials and natural plants in the 1400–2000 nm band. The difficulty of simulating the natural plant spectrum lies in reproducing the absorption peak of water by increasing the water content in a camouflage material. Herein, a mesoporous (MS) material is used to simulate the plant spectrum because such material can absorb and retain a large amount of water. MS was prepared via a two‐step method using tetraethyl orthosilicate and tetrabutyl titanate. The characteristics of the as‐prepared MS were examined via X‐ray diffraction, transmission electron microscopy, ultraviolet–visible diffusion reflectance spectroscopy and nitrogen adsorption–desorption isotherms. In addition, a film was prepared using the fully absorbent mesoporous material, and the water content was determined via near‐infrared spectroscopy and thermogravimetric analysis. The bonding between the mesoporous material and resin was examined via field emission gun scanning electron microscopy. The mechanical properties of the film were measured by a pendulum hardness tester and a cylindrical bending tester. The results indicate that low‐temperature synthesis followed by high‐temperature hydrothermal treatment is conducive to expanding the mesopore aperture, reaching a maximum of 23 nm. Moreover, the regular structure of the as‐prepared titanium‐containing mesoporous material is maintained under high hydrothermal temperature. The mesoporous film exhibits a good water absorption capacity of up to 80% by mass and can effectively simulate the spectrum of plants. The mechanical properties of the film are good, and the hardness of the film is related to the content of mesoporous powder. © 2023 Society of Industrial Chemistry.

Tracking post-storage apple age with polarized light measurements

A rotating retarder fixed polarizer (RRFP) polarimeter operating in the 600 – 1000 nm range was developed and used to measure the polarized reflected light response of post-storage apples. The degree of polarization (DOP) changes on two apple cultivars, Malus x domestica Borkh. (‘Scired’, marketed as Bay Queen®) and Malus x domestica Gala (‘Royal Gala’), was measured as the apples aged at room temperature and humidity (∼22 °C and 65%RH respectively) over an 18-day period. The DOP values were highest at 600 nm with observable peaks around the chlorophyll-related absorption at 675 nm, especially for the Bay Queen cultivar, and around the water-related absorption at 970 nm. The values between 700 and 900 nm were featureless and flat at half the peak values. The DOP values for circularly polarized light were about 50% lower over most of the spectral range than those for linearly polarized light. Overall, the DOP values decreased with apple age. There was a strong linear trend for individually tracked apples that was well correlated with non-destructive impact probe firmness measurements. The DOP loss rate was highest below 700 nm, peaking notably for Bay Queen at 675 nm, and is consistent with a probable loss with aging of visible-range pigment absorbers in the near surface region. In contrast, the DOP loss rate was spectrally near flat above 700 nm, suggesting there are no near-infrared absorber losses in the near surface region of the fruit. There was no evidence of an increased DOP loss rate near the water absorption peak at 970 nm, suggesting the water concentration in the near surface region is effectively constant over the 18-day aging period and despite a 5% total loss of water from the whole fruit. While the individually tracked apples trended linearly with age and correlated with non-destructive firmness, the relationships were very inconsistent between the apples. Also, no trends with age or correlations with firmness could be established for measurements on other untracked apples sampled independently from the same aging populations and tested destructively at each day. It is surmised that DOP reflectance measurements are unlikely to be useful for the direct and non-destructive prediction of internal fruit quality parameters such as firmness.

Rapid determination of the moisture content of triethyleneglycol dinitrate absorption tablets by near-infrared spectroscopy

During the production of triethyleneglycol dinitrate (TEGDN) double-based propellants, excessive moisture content adversely affects the plastination of TEGDN absorption tablets. This study focused on developing a model for detecting moisture content in the TEGDN absorption tablets by near-infrared spectroscopy (NIRS). The spectral intervals of 1149.7–1248.8 nm and 1397.4–1515.1 nm were determined according to the competitive adaptive reweighted sampling (CARS) algorithm and comparison of the absorption peaks of TEGDN absorption tablet samples and the absorption peak of water. A combination of standard normal variables transformation (SNV) and first-order derivative (FD) was selected as the original spectral pre-processing method. The optimum number of factors for the moisture model was chosen as 7. A moisture quantification model was developed based on the Partial Least Squares (PLS) algorithm. The determination coefficient of the calibration and cross-validation (Rc2,Rcv2) were 0.9905 and 0.9869, respectively. The root means square error of the calibration and cross-validation (RMSEC, RMSECV) were 0.0158 and 0.0186, respectively. The developed moisture model was externally validated using a prediction set. The determination coefficient of the prediction (Rp2) was 0.9899, and the root mean square error of the prediction (RMSEP) was 0.0207. The mean absolute and mean relative errors between the predicted values of the NIRS method and the measured values of the traditional method were 0.0091 and 1.0819%, respectively. Therefore, the results show that the moisture model developed by NIRS can quickly and accurately detect the moisture content of TEGDN absorption tablets after removing moisture and determine whether the TEGDN absorption tablets are qualified.

Effect of soluble dietary fibre from barley on the rheology, water mobility and baking quality of wheat flour dough

Incorporation of dietary fibre in a bread recipe is a technological challenge. Therefore, the aim was evaluating the impact of substitution of wheat flour with extracted soluble dietary fibre from barley (BDF) at two levels (4.0% and 8.0%) on dough and bread characteristics. The percent water absorption and mixograph peak mixing time increased for both BDF substitution levels, while T22 relaxation time reduced significantly. In addition, 4.0 and 8.0% BDF substitution levels resulted in a 20.6% and 33.4% reduction in freezable water (FW) content, respectively, and increased G′ and G″ values. In creep tests, BDF dough showed reduced creep compliance values and recoverable strain percentages. BDF limits the water availability in dough for the other biopolymers as reflected in more β-sheet structures, reduced water mobility and lower FW content. The reduction in water availability results in impaired development of an elastic gluten network and an increased resistance to deformation, eventually translating in higher crumb hardness and lower loaf volume. These insights can serve as basis for targeted interventions to recipes and processing to counteract the adverse effects of BDF on bread properties. This study also revealed that 4.0% BDF substitution of wheat flour does not adversely affect bread quality.

Structure and near-infrared spectral properties of mesoporous silica for hyperspectral camouflage materials

Mesoporous silica materials were prepared via a hydrothermal method by adjusting the content of trimethylbenzene (TMB) and PEO-PPO-PEO block copolymer (F127) in mesoporous silica. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy(TEM), nitrogen adsorption–desorption analysis(BET),Fourier transform-infrared spectroscopy (FTIR) and Visible near infrared spectrophotometry (VIS-NIR). The effects of mesoporous structure on the water load capacity and near-infrared spectra were systematically then studied. The results showed that the pore size and volume of the mesoporous silica could be tuned by varying the dosage of TMB and F127. In addition, the hygroscopicity of the mesoporous silica was linearly dependent on the pore size and volume, and the as-prepared mesoporous silica had NIR spectral features similar to those of vegetation leaves. More interestingly, as the water content increased, the water absorption peak of the mesoporous silica in the NIR wavebands was closer to that of natural leaves, showing greater similarity. Finally, camouflage coatings were prepared by using the as-prepared mesoporous silica powder as a functional filler and water-borne polyurethane as an adhesive. The cosine similarity between the camouflage coating and natural leaves reached 98.49%, suggesting that the camouflage coating achieved strong similarity in simulating the reflection spectra of plant leaves, potentially providing a new approach to the design of functional fillers of camouflage materials.

Optimizing Retinal Thermofusion in Retinal Detachment Repair: Achieving Instant Adhesion without Air Tamponade.

Rhegmatogenous retinal detachment repair by intraoperative sealing of the tear without a tamponade agent should enable faster restoration of vision and resumption of normal activities. It avoids the need for further surgery in the case of silicone oil endotamponade. This study evaluated the retinal thermofusion (RTF) retinopexy method of subretinal space dehydration before photocoagulation to create an instantaneous intraoperative retina reattachment in a preclinical model. Preclinical study. Twenty Dutch Belt, pigmented rabbits that underwent RTF repair after experimental retinal detachment. This exvivo model quantified adhesion force between the retina and underlying retinal pigment epithelium and choroid after treatment of 1 retinal edge using postmortem porcine or human retina (6× 12 mm). We compared (1) control, (2) laser photocoagulation alone, (3) dehydration alone, and (4) dehydration followed by photocoagulation (RTF). Optimized parameters for RTF were then applied in the invivo rabbit model of retinal detachment. Animals were followed up for 14 days. For this exvivo model, we measured adhesion force and related this to tissue temperature. For the invivo study, we assessed retinal attachment using funduscopy and histologic analysis. The exvivo model showed that RTF repair produced significantly higher adhesion force than photocoagulation alone independent of dehydration method: warm (60° C) high airflow (50-70 ml/minute) or using laser wavelengths targeting water absorption peaks (1470 or 1940 nm) with coaxial low airflow (10-20 ml/minute). The latter approach produced a smaller footprint of dehydration. Application of RTF (1940-nm laser with coaxial airflow) in an invivo retinal detachment model in rabbit eyes resulted in immediate retinal adhesion, achieving forces similar to those in the exvivo experiments. Retinal thermofusion repair resulted in stable reattachment of the retina over the 2-week follow-up period. We showed that a short preliminary dehydrating laser treatment of a retinal tear margin before traditional laser photocoagulation creates an immediate intraoperative waterproof retinopexy adhesion independent of tamponade and a wound-healing response. This approach potentially will allow rapid postoperative recovery regardless of the tear location and improved vision.

Underwater Performance Analysis of Perovskite Solar Cells

Herein, perovskite solar cells are fabricated and tested in underwater conditions in the laboratory. The fabricated perovskite solar cell (PSC) shows an efficiency of 14.29% outside water. It demonstrates an impressive power density of 10.49 and 11.88 mW cm−2 at a depth of 10 cm in seawater and deionized (DI) water environment, respectively. Compared with commercial silicon solar cells, PSCs are less affected by the water depth level due to their wide bandgap. The quantum efficiency measurement studies show that the perovskite solar cell is quite unaffected over the 400–800 nm wavelength in underwater environment. On the other hand, the spectral response of silicon solar cell is significantly hampered in the infrared region (700–1050 nm) due to light absorption by water. Absorption peaks of water correspond to the observed dips in quantum efficiency spectra of solar cells, indicating that light absorption due to water is primarily responsible for the decrease in photocurrent and electrical performance in underwater conditions.

Physicochemical, antioxidant and starch-digesting enzymes inhibitory properties of pearl millet and sweet detar gluten-free flour blends, and sensory qualities of their breads

Natural sources of hydrocolloids may serve as healthier alternatives to modified hydrocolloids as gluten replacement in gluten-free food products. In this study, the physicochemical, antioxidant and starch-digesting enzymes inhibitory properties of gluten-free whole pearl millet flour (PMF) blended with 1.5% and 3% of either sweet detar flour (SDF, a natural source of hydrocolloids) or sodium carboxymethyl cellulose (SCMC, a modified hydrocolloid), and the sensory qualities of their breads were evaluated. White wheat flour (WWF) and its bread served as the control flour and bread, respectively. Amylose level and solubility index of the blends decreased, whereas their water absorption capacity, peak and final viscosity increased significantly as their proportions of SDF and SCMC increased. Total phenolics, tannins, and total flavonoids contents; DPPH•, ABTS•+ scavenging capacity, and reducing power; α-amylase and α-glucosidase inhibitory activities were significantly higher in PMF and its blends with SDF and SCMC than in the WWF. Further, the blend of PMF and 1.5% SDF had a stronger α-amylase and α-glucosidase inhibitory activity than those of PMF and SCMC (1.5 and 3%). Although the sensory qualities of the WWF bread were better than those of PMF and its blends with SDF and SCMC, the sensory qualities of PMF-SDF and PMF-SCMC breads were comparable. The study indicates that SDF could be a good substitute for SCMC in the development of PMF-based gluten-free bread, with an enhanced starch-digesting enzymes inhibitory property, targeting celiac disease and type 2 diabetes patients.

Pavement condition sensor based on a dual optical frequency comb generator

A pavement condition sensor aims to estimate the pavement surface grip, and therefore the sensor must detect the presence of water, snow, slush or the like on the surface of the pavement. The leading technology for such a sensor is near infrared diffuse reflectance spectroscopy using a wavelength range around a water absorption peak. In this paper we present a pavement condition sensor based on said technique that uses an electro-optic dual optical frequency comb generator as optical source. The proposed sensor provides unique properties in terms of measuring integration time that are necessary to advance the pavement condition several meters ahead of a moving vehicle.

Fiber optic soil water content sensor for precision farming

In this work, we propose a novel and cost effective fiber optic platform for the continuous monitoring of soil water content to be exploited in the agri-food sector and, in particular, in the field of precision agriculture to promote the rational use of water resources. The proposed platform arises from the judicious connection of optical fiber technology and functional materials able to exhibit a change in their optical properties depending on the water content in the environment.Al2O3 disks have been used as functional materials, taking advantage of their capability to absorb water and exhibit a correlated absorbance increase in the wavelength range corresponding to the absorption peak of water. A detailed study has been carried out to obtain the best coupling conditions between optical fibers and the functional disk. The final prototype has been tested directly in soil and the collected results show its capability to detect soil water content variation in the range 0–35% of volumetric water content (VWC) with a sensitivity of 2.3%/%VWC and a VWC resolution lower than 1%. Such performances allow the proposed device to be used for soil water content measurements for applications in several fields and in different hydrogeological conditions, such as, e.g., in smart farming applications, to support farmers in defining a correct irrigation strategy, or for the real-time monitoring of hydrogeological hazard, to prevent rainfall-induced landslide.Moreover, thanks to the capability of optical fibers technology to multiplex different fiber probes while sharing the same interrogation equipment, the proposed platform is endowed with multiplexing capabilities and presents a solid basis for a continuous monitoring of soil moisture monitoring over large areas.

Thulium fiber laser in urology: physics made simple.

In this narrative review, we will focus on a novel thulium fiber laser's physical properties in terms of its clinical applicability. TFL has successfully moved forward from the preclinical trials into clinical practice and now is being widely used in clinics around the world. The available data suggest that the device effectively operates in soft tissues - benign prostate hyperplasia (BPH) and bladder tumors, as well as in lithotripsy. Also, the first promising results were obtained from laparoscopic surgery showing its possible applicability in the management of renal cell carcinoma. The constructional changes in fiber laser's design, lead to alteration of laser-tissue interactions, which resulted in clinical advantages of the device. Yet, the exact mechanism often is considered complex for understanding. With this work, we are aiming to build a bridge between biophysics and clinical practice and give a simple explanation of how the devices is working and why the knowledge of it is important for a clinician. The more effective wavelength (closer to the water absorption peak), favorable beam profile, different modes of action allowing to decrease carbonization on one hand and retropulsion on the other, all this makes TFL an evolution in urologic surgery. Further trials investigating on the possible pros and cons of the device are awaited.

Infrared spectroscopic identification of mineral drugs in herbal preparations with thermogravimetry-guided thermal separation–A case study of alum in a herbal powder for oral ulcer

Identification is the first step to ensure the quality and safety of mineral drugs in herbal preparations. Fourier transform infrared (FTIR) spectroscopy is a simple, rapid, cheap and green technique to identify mineral drugs that are solid materials mainly composed of inorganic ingredients. However, the spectral peaks of mineral drugs are often covered by the absorption bands of other ingredients in the FTIR spectra of herbal preparations. According to the different thermal stabilities of the compositions of herbal preparations, thermal separation procedures can be designed by thermogravimetry (TG) and FTIR analysis to eliminate the spectral masks of other ingredients on mineral drugs. As a result, FTIR spectra of the heated samples can provide more intuitive and reliable evidences for the identification of mineral drugs in preparations. In this research, an FTIR method with TG-guided thermal separation was developed to identify the alum in Kouqiang Kuiyang San (KKS) that is a traditional Chinese medicinal preparation for oral ulcer. TG and FTIR analysis of KKS simulation mixtures and related herbal materials suggested that heating at 250 °C for 1 h can remove the absorption peaks of water and organic molecules but remain the characteristic peaks of NH4+ and 2CaSO4⋅H2O above 3000 cm−1. Adulterated and deteriorated commercial KKS preparations were found by the FTIR method with thermal separation. This research illustrates the feasibility of FTIR spectroscopy and TG-guided thermal separation for the rapid and accurate identification of mineral drugs in herbal preparations.

Comparative Study of Unheated and Heated Rubies from Myanmar

A batch of unheated and heated rubies from Myanmar were obtained from a gemstone processor in Thailand. The gemmological characteristics, chemical composition characteristics, infrared spectrum characteristics and UV-Vis absorption spectrum characteristics were tested and analyzed, so as to obtain the characteristics of the rubies after heat treatment and distinguish them from the unheated rubies from Myanmar. The test results showed that a large number of secondary melt inclusions were found in the heated rubies, while only mineral crystal inclusions and fluid inclusions were observed in the unheated rubies. In terms of chemical composition characteristics, the average content of Ti element in heated rubies is about 1 000 ppm higher than that in the unheated rubies, and the average content of Fe element in heated rubies is about 100 ppm lower than that in the unheated rubies. Absorption peaks of daspore, structural water and free water can be detected in unheated rubies, but these characteristic absorption peaks can not be detected in heated rubies due to the damage of high temperature. Compared with unheated rubies, the fluorescence peak of heated rubies near 694 nm is stronger and sharper.

Effect of cashew nut protein concentrate substitution on the physicochemical properties, antioxidant activity and consumer acceptability of wheat bread.

The effect of incorporating different proportions (5, 10, 15 and 20%) of cashew nut protein concentrate (CNPC) on the physicochemical properties, antioxidant activity and consumer acceptability of bread was investigated. Substitution of wheat flour with CNPC increased the water and oil absorption capacity, swelling capacity, peak and final viscosities. Substitution of CNPC in wheat bread significantly increased the protein (12.69-22.04g/100g), ash, crude fiber, calcium, magnesium, iron (2.09-3.36mg/100g), phosphorus and zinc (0.79-1.57mg/100g) content, while carbohydrate value decreased. Substitution of wheat flour with CNPC in bread increased the loaf weight while specific volume decreased (4.36-2.21 cm3/g). Acceptable bread was prepared with up to 15% CNPC; which contained the highest total phenolics (2.64mg GAE/g), DPPH radical scavenging activity (71.22µmol TE/100g), ferric reducing antioxidant power (427.77µmol TE/100g) and ABTS radical scavenging activity (195.68µmol TE/100g) than the 100% wheat bread (1.28mg GAE/g, 40.81µmol TE/100g, 375.62µmol TE/100g and 154.02µmol TE/100g).

Effect of Brachystegia Eurycoma Flour Addition on the Physicochemical Properties of Whole Millet Flour and the Sensory Attributes of its Gluten-Free Bread

Abstract This study evaluated the effect of addition of Brachystegia eurycoma flour (BEF), a natural source of hydrocolloids, on the physicochemical properties of whole millet flour (WMF) and the sensory attributes of its gluten-free bread. BEF and sodium carboxylmethyl cellulose (a reference hydrocolloid) were added to WMF at 1.5 and 3% proportions, and breads were baked from the blends. Wheat flour (100%CWF) bread served as the control. Amylose level decreased significantly (p < 0.05), while water absorption capacity, peak and final viscosities of the blends increased with increasing proportion of BEF. The 100%CWF bread had better sensory qualities than WMF-BEF breads. Hence, BEF improved the physicochemical properties of WMF-BEF blend, but did not alter the sensory qualities of its gluten-free bread.

Hyperspectral parameters and prediction model of soil moisture in apple orchards

In this study, the apple orchard of Shuangquan town in mountainous and hilly area of central Shandong Province was taken as the research area. The relationship between the ratio spectral index (RSI), difference spectral index (DI) and normalized difference spectral index (NDSI) and soil moisture content in the range of 400nm-2450nm was explored, and then a quantitative estimation model of soil moisture content was build. The results show that the correlation between soil moisture content and spectral reflectance can be improved by different spectral index calculation. The sensitive modeling areas determined by RSI, DI and NDSI are all near the third water absorption peak, among which RSI (R2304, R2081), RSI (R2306, R2080), RSI (R2306, R2081), RSI (R2307, R2079), RSI (R2307, R2080), RSI (R2307, R2081), RSI (R2308, R2080) and RSI (R2308, R2081) the PLSR regression equation constructed for independent variables has the best estimation effect, the largest determination coefficient (R2 = 0.7918), and the smaller Root Mean Square Error (RMSE = 0.0054). The selection of full band spectral index can better extract effective information, and significantly improve the accuracy and adaptability of soil moisture spectral estimation model.

Effect of cereal endospermic cell wall on farinographic and mixographic characteristics of wheat flour

In this study, the effect of cereal endospermic cell wall from wheat, barley, and sorghum on rheological properties with special reference to farinographic and mixographic characteristics of wheat flour dough was observed. For the purpose, endospermic cell wall was isolated from two varieties of each cereals by using popping method. Moreover 1% and 2% of cereal endospermic cell walls were added in wheat flour and farinographic (i.e., water absorption capacity, dough development time, dough stability, softness of dough, mixing tolerance index [MTI]) and mixographic characteristics (i.e., mixing time and peak height) were determined through farinograph and mixograph. Results revealed that rheological properties of wheat flour were significantly improved by the addition of cereal cell walls. Higher increase in water absorption capacity (70.56 ± 0.32%), dough stability (7.77 ± 0.19 min), peak height (70.41 ± 0.34 BU), and MTI (73.59 ± 0.33%) of dough was observed with the addition of barley cell wall followed by wheat and sorghum cell walls at 2%. Moreover dough development time (3.13 ± 0.34 min), mixing time (4.32 ± 0.07 min), and softness of dough (125.60 ± 0.29%) were decreased more significantly through barley cell wall than wheat and sorghum cell walls. Conclusively, utilization of cereal cell wall in cereal-based products improve product quality. Practical applications Cereal cell wall is the layer of polysaccharides, that is, cellulosic and non-cellulosic. These components improve the farinographic and mixographic properties of dough. Cell wall has higher polysaccharides than grain. In this study, cereal cell walls (from wheat, barley, and sorghum) were added in wheat flour and various properties of wheat dough such as water absorption capacity, dough development time, mixing time, softness of dough, dough stability, MTI, and peak height were improved. In nutshell, utilization of cell wall in cereal-based products can fulfill many objectives including improving product quality, shelf life, value addition, and maintaining good health of the consumers. Novel products with improved rheology can be introduced in market as functional foods against various diseases such as diabetes mellitus, cancer, bacterial infections.

Er-doped crystalline active media for ~ 3 μm diode-pumped lasers

Lasers based on erbium ions using 4I11/2 ​→ ​4I13/2 transition can generate laser radiation in the spectral range from 2.7 ​μm to 3 ​μm. Since the strong absorption peak of water is located at 3 ​μm, there has been an effort to develop a suitable laser source for various medical applications, e.g. dentistry, dermatology, urology, or surgery. Laser radiation from this wavelength range can also be used in spectroscopy, as a pumping source for optical parametric oscillators, or for further mid-infrared conversion.This paper represents an overview of the erbium-doped active media (e.g. Er:YAG, Er:YAP, Er:GGG, Er:SrF2, Er:YLF, Er:Y2O3, Er:KYW, etc.) for laser radiation generation in the spectral range 2.7–3 ​μm. In the first part of this paper, the particular active media are discussed in detail. On the other hand, the experimental results summarized absorption and emission cross-section spectra together with decay times at upper (4I11/2) and lower (4I13/2) laser levels of all tested Er-doped samples at room temperature. Moreover, laser results in CW and pulsed laser regime with tunability curves, achieved in recent years, are presented, too.