Droplet Area Research Articles

High-throughput fat quantifications of hematoxylin-eosin stained liver histopathological images based on pixel-wise clustering

Besides diagnosis of fatty liver disease (FLD) using multiple medical imaging techniques in clinic, accurate fat quantification of liver tissue slice, especially the fat droplets measurement, is still a critical indicator in related pathological researches. Stained by hematoxylin-eosin (HE), different tissue components with different colors need to be identified and measured manually in conventional approaches. Automated liver fat quantification of HE stained images remains challenging because forms and distributions of fat are extremely irregular with no clear boundaries, especially in conducting high-throughput analysis which demands quick processing and higher accuracy for the reference of pathologists. To solve this problem, we propose an automated liver fat quantifications pipeline of HE stained images based on pixel-wise clustering, which firstly extracts high-relevant pixel-level features with color mode transformation, then locates boundaries between nuclei, fat and other components by clustering image pixels in an unsupervised mode, and finally identifies indicative fat droplets based on a set of morphological criteria. The pipeline was verified in analysis of multifold fatty liver treatment assays, with experimental results showing high accuracy and adaptability in fat droplets quantification despite data variance. Quantitative indicators provide a reliable evidence for relevant pathological researches or therapy selection, in which number and average area of indicative fat droplets increased sharply in severe and moderate-grade FLD respectively. Those indicators might be utilized as surrogate biomarkers for further researches.

Altering the coffee-ring effect by adding a surfactant-like viscous polymer solution

A uniform deposition of the suspended particles in an evaporating droplet is necessary in many research fields. Such deposition is difficult to achieve, because the coffee-ring effect dominates the internal flow in a droplet. The present study adopts a biocompatible, surfactant-like polymer (Polyethylene glycol, PEG) to break the coffee-ring effect and obtain a relatively uniform deposition of the microparticles with yielding multi-ring pattern over a droplet area. Movements of the suspended particles in evaporating droplets and deposition patterns of them on a glass substrate were analyzed with microscopic images and video files. The PEG in the droplets successfully altered the coffee-ring effect because of the surface tension variation, which induced a centripetal Marangoni flow. Balancing these two phenomena apparently generated the Marangoni vortex. For PEG solution droplets, the pinning–depinning process during evaporation was periodically repeated and multiple rings were regularly formed. In conclusion, adding a surfactant-like viscous polymer in a droplet could provide a uniform coating of suspended particles, such as cells and various biomaterials, which would be essentially required for droplet assays of biomedical applications.

A kinetic study of the biological catalytic hydration of acrylonitrile to acrylamide

In this study, the kinetic characteristics of the bio-hydration of acrylonitrile by free cell catalysts were studied. Due to the aggregation phenomenon, free cell catalysts showed different characteristic when compared with free enzyme catalysts. The Michaelis constants were obtained through the homogeneous reaction. Both the values of Vm and Km increased with the increase in enzymatic activity, ranging from 100 to 500U/mL, and the variation trend of Km was not consistent with the rule of enzyme-catalyzed reaction. To reduce the external diffusion resistance of acrylonitrile to free cells, a membrane dispersion micro-reactor was used, and the conversion rates of acrylonitrile in the membrane dispersion micro-reactor under all of the experimental conditions reached approximately 90% of the max conversion rates. The reinforcement of the apparent reaction rate by the micro-reactor may have benefitted from the significant increase in the specific surface area of the acrylonitrile droplets and the adsorption of the free cell catalysts on the undissolved droplets.

(-)-Hydroxycitric Acid Reduced Lipid Droplets Accumulation Via Decreasing Acetyl-Coa Supply and Accelerating Energy Metabolism in Cultured Primary Chicken Hepatocytes

Background/Aims: (-)-Hydroxycitric acid (HCA) had been shown to suppress fat accumulation in animals and humans, while the underlying biochemical mechanism is not fully understood, especially little information is available on whether (-)-HCA regulates energy metabolism and consequently affects fat deposition. Methods: Hepatocytes were cultured for 24 h and then exposed to (-)-HCA (0, 1, 10, 50 µM), enzyme protein content was determined by ELISA; lipid metabolism gene mRNA levels were detected by RT-PCR. Results: (-)-HCA significantly decreased the number and total area of lipid droplets. ATP-citrate lyase, fatty acid synthase and sterol regulatory element binding protein-1c mRNA level were significantly decreased after (-)-HCA treatment, whereas peroxisome proliferator-activated receptor α mRNA level was significantly increased. (-)-HCA significantly decreased ATP-citrate lyase activity and acetyl-CoA content in cytosol, but significantly increased glucose consumption and mitochondrial oxygen consumption rate. (-)-HCA promoted the activity/content of glucokinase, phosphofructokinase-1, pyruvate kinase, pyruvate dehydrogenase, citrate synthase, aconitase, succinate dehydrogenase, malate dehydrogenase, NADH dehydrogenase and ATP synthase remarkably. Conclusions: (-)-HCA decreased lipid droplets accumulation by reducing acetyl-CoA supply, which mainly achieved via inhibition of ATP-citrate lyase, and accelerating energy metabolism in chicken hepatocytes. These results proposed a biochemical mechanism of fat reduction by (-)-HCA in broiler chickens in term of energy metabolism.

Seasonal changes in the liver of a non-hibernating population of water frogs, Pelophylax kl. esculentus (Anura: Ranidae)

Seasonal variation of liver glycogen, lipids and melanomacrophages were investigated in a non-hibernating population of Pelophylax kl. esculentus from Calabria by histochemical methods and computer-assisted image analysis. Twenty individuals of both sexes were sampled in a tank in Roseto Capo Spulico (Cosenza, Calabria) in four periods of the year 2016 (February, May, July, October). Portions of liver from each individual were included in paraffin for glycogen and melanomacrophages, and epoxydic resin-araldite for lipid analysis. Sections were stained with periodic acid-Schiff (PAS) for glycogen (with diastase-PAS as control) or osmium-tetroxide for lipids, or left unstained for melanomacrophages (appearing naturally black due to melanin). Image analyses were performed on 9–12 grayscale converted pictures per individual. Total areas per µm2 of glycogen, lipids and melanomacrophages, as well as counts of lipid droplets and melanomacrophages and mean area of single lipid droplets and melanomacrophages, were measured. Statistical analyses were performed by analysis of variance (ANOVA) with bootstrap resampling. Significant variation among sampling periods was found for each variable. Glycogen and lipids co-vary, with higher values observed in October–February and lower values in May–July, whereas melanomacrophages reach a peak in May and have much lower values in the other months. It is concluded that, in the absence of a hibernating period, reproduction is the main force regulating the annual cycles of reserve storing and melanin production.

Upgrading of crude oil in supercritical water: A five-lumped kinetic model

Experiments on upgrading crude oil in supercritical water (SCW) were conducted in an autoclave to investigate the influence of reaction conditions on pyrolysis and a five-lumped kinetic model was established. It can be illustrated that coke is mainly generated by asphaltenes and changing phase structure of the reaction system and enlarging the specific surface area of asphaltenes droplets via increasing water density or water-oil ratio can enhance the output of light components and suppress the formation of coke. The five-lumped kinetic model consists of saturates, aromatics, resins, asphaltenes, coke and coincides well with the experimental data.

An experimental study on removal of exhaust gas recirculation cooler fouling using washer fluid steam

Lowering the temperature of recirculated gas in an exhaust gas recirculation (EGR) system reduces the emission of nitrogen oxide (NOx). However, the EGR cooler can become polluted by PM in recirculated EGR gas, which reduces the cooling efficiency and the gas flow rate. A steam EGR cooler fouling remover (SECFR) system was designed using evaporated washer fluid to remove fouling on the cooler surface. However, the injection pressure is only 5bar, which is not sufficient to atomize the washer fluid. Therefore, in this study, an impinging plate was used to promote the atomization of sprayed washer fluid, and the droplet area ratio (DAR) and droplet uniformity index (DUI) were measured through quantitative analysis of high-speed images. Finally, the performance. of the SECFR system was evaluated in a real diesel engine.

Effect of Air-assisted Spray Application Rate on Spray Droplet Deposition Distribution on Fruit Tree Canopies

<abstract> <b><i>Abstract. </i></b> To improve the utilization rate of pesticides and the adaptability of the application machinery to different canopies and to construct a matching relation between the application rate and the characteristics of fruit trees, this article introduces spray droplet coverage rate and deposition as the investigation indexes. Five different application rates were used with the purpose of investigating the effect of the application rate on spray droplet deposition coverage under different canopy characteristics and quantitatively describing the optimum application rates for different canopies. According to the results of the application with under air-assisted sprayer, the recommended spray application rates for the three types of canopies in the present article were 0.25, 0.20, and 0.14 L/tree in average, which is compared with the traditional manual application rate of 0.25 L/tree in average. To achieve the same level of application effect with traditional manual application, the air-assisted application rate for large and medium canopies can be reduced to 0.20Â L/tree in average, this is a decrease of ¹/₅. Compared with the upside coverage rate of the spray droplets, the underside coverage rate of the spray droplets was more significantly affected by the reduction in the application rate. In addition, in the case of a higher spray droplet deposition and a lower dispersion degree, there would be an inconsistency between the spray droplet coverage rate and the deposition indexes. Thus, it is also necessary to measure the uniformity of the spray droplet dispersion on the leaf surface (spray droplet dispersion index) and the effective lethal area of the spray droplets, which will enable a more accurate expression of the application effect.

Mechanics of Droplet Interface Bilayer “Unzipping” Defines the Bandwidth for the Mechanotransduction Response of Reconstituted MscL

Fully fluidic three‐phase droplet interface bilayers (DIBs) are convenient systems for studies of physiochemical properties of lipid‐stabilized interfaces as well as for reconstitution of biological molecules involved in ion transport, sensing, and energy conversion. Recently, it was reported that the low‐threshold mutant of the bacterial mechanosensitive channel MscL can be transiently activated in DIBs under harmonic mechanical stimulation. However, the experimentally determined range of oscillation frequencies generating sufficient tension for MscL gating is narrow (0.1–0.3 Hz). Here, physical parameters of the system that define tension in the interface bilayer under equilibrium and dynamic regimes and their variations during viscoelastic responses of droplets to compression and retraction, are analyzed. It is found that the rate of interfacial bilayer “unzipping” during the retraction phase limits the process of droplet area relaxation, thus preventing tensile expansion in the subsequent cycles. This article proposes temporally asymmetric stimulation protocols with variable ratio of compression to retraction phases (duty cycle), which allows the slow shape relaxation process and stimulates MscL much more efficiently. The new protocol activates a larger proportion of MscL's fully open states relative to the population of subconductive states over a wider range of frequencies.

Understanding and Discrimination of Biofilms of Clinically Relevant Microorganisms Using Surface-Enhanced Raman Scattering

Biofilm formation is a defense mechanism for microorganisms to survive under both natural and stress conditions. Clinically relevant microorganisms threaten patient health through biofilm formation on medical devices and implants. It is very important to identify biofilm formation in order to suppress their pathogenic activities in early stages. With the aim for better understanding biofilm formation and possibility of detection, in this study, biofilm formation of clinically important microorganisms, Pseudomonas aeruginosa, Staphylococcus epidermidis, and Candida albicans are monitored with surface-enhanced Raman scattering (SERS). The SERS spectra were collected by mapping a dried droplet area where a volume of colloidal silver nanoparticle (AgNP) suspension is placed on microorganism culture plate. The spectral changes on the SERS spectra with increasing incubation time of the model microorganisms from 4 to 120 h are monitored. The unique spectra originating from the biofilms of three pathogenic microorganisms and the spectral changes as a result of time-dependent concentration fluctuations of biomolecular species in their biofilms including carbohydrates, lipids, proteins, and genetic materials allow not only identification but also discrimination of biofilms using principal component analysis.

Hepatic mitochondrial oxidative phosphorylation is normal in obese patients with and without type 2 diabetes.

Hepatic insulin resistance in patients with obesity or type 2 diabetes has been suggested to result from hepatic mitochondrial dysfunction. High-resolution respirometry (HRR) can be used to assess oxidative phosphorylation by measuring the mitochondrial oxygen consumption rate in the individual complexes of the mitochondria. By using HRR, the present study demonstrates no difference in hepatic mitochondrial oxidative phosphorylation among subjects with obesity with or without type 2 diabetes and non-obese controls. Furthermore, the amount of mitochondria, assessed by the citrate synthase activity, is not different between the three groups. Together the present findings indicate that hepatic mitochondrial oxidative phosphorylation capacity is not impaired in patients with obesity or type 2 diabetes. Obese patients with type 2 diabetes (T2DM) and without type 2 diabetes (OB) are characterized by high hepatic lipid content and hepatic insulin resistance. This may be linked to impaired hepatic mitochondrial oxidative phosphorylation (OXPHOS) capacity. The aim of the present study was to investigate and compare hepatic mitochondrial OXPHOS capacity in T2DM, OB and non-obese controls (CON). Seventeen obese patients (nine OB and eight T2DM) and six CON patients had perioperative liver biopsies taken. Samples were divided into three parts to measure (1) complex I, II and IV linked respiration, (2) citrate synthase (CS) activity and (3) lipid droplet (LD) size and area (% of total tissue area filled by LDs). State 3 respiration of complex I, II and IV and the CS activity did not differ in OB, T2DM and CON. LD size was significantly higher in T2DM compared with CON, and LD area tended (P=0.10) to be higher in T2DM and OB compared with CON. The present findings indicate that hepatic OXPHOS capacity is not different in patients with markedly different weight and glycaemic control. Furthermore, the results do not support impaired hepatic mitochondrial respiratory capacity playing a major role in the development of obesity-induced type 2 diabetes.

A brominated flame retardant 2,2⿲,4,4⿲ tetrabrominated diphenyl ether (BDE-47) leads to lipogenesis in the copepod Tigriopus japonicus

De novo lipogenesis (DNL) is a fatty acid synthesis process that requires several genes, including sterol regulatory element binding protein (SREBP), ATP-citrate lyase (ACLY), and acetyl-CoA carboxylase (ACC). DNL up-regulation is able to induce fat accumulation through an increase in fatty acids. To investigate the relationship between DNL up-regulation and the accumulation of fatty acids and lipid droplets in response to 2,2⿲,4,4⿲ tetrabrominated diphenyl ether (BDE-47), we examined DNL in the copepod Tigriopus japonicus. Transcription levels of DNL-related genes were increased after exposure to 2.5μg/L BDE-47 for 24h. After exposure to 2.5μg/L BDE-47, palmitic acid was significantly increased (P<0.05) at days 1 and 4, along with upregulation of fatty acid synthesis-related genes (e.g., desaturases and elongases). However, docosahexaenoic acid and arachidonic acid were down-regulated at days 1 and 4, showing an antagonistic effect. Lipid droplet area significantly increased in Nile red staining analysis after 24h of exposure to 2.5μg/L BDE-47 in T. japonicus, while DNL was down-regulated in response to 500μM salicylate (a lipogenesis inhibitor), indicating that BDE-47 exposure is closely associated with an increase in fatty acids in this copepod. This study provides a better understanding of the effects of BDE-47 on DNL in copepods.

Coverage Area and Fading Time of Surfactant-Amended Herbicidal Droplets on Cucurbitaceous Leaves

Proper use of appropriate surfactants to control droplet behavior on leaf surfaces is critical to improving herbicide application efficacy for controlling paddy melons (). An esterified seed oil surfactant and a petroleum oil surfactant were investigated to modify spread areas and fading times of water and herbicidal droplets on watermelon leaves, which were used to simulate paddy melon leaves. A combination of two systemic herbicides (triclopyr and glyphosate) was also used to form a water-based spray solution for comparisons. The glyphosate herbicide was pre-formulated with a non-ionic surfactant. Tests were conducted with 250 and 450 I¼m sessile droplets at 30% and 60% relative humidity (RH) inside a controlled environmental chamber. The sessile droplets were produced with a single-droplet generator. Droplet fading times significantly increased with both droplet size and RH. Droplet maximal coverage areas increased only with droplet size but not RH. For the water-only solution, addition of seed oil surfactant increased the droplet coverage area by over 2.3 times, but addition of the petroleum oil surfactant did not increase the droplet coverage area. For the spray solution containing two herbicides, addition of the seed oil surfactant increased droplet coverage areas on leaves from 0.146 ±0.012 mm 2 to 0.201 ±0.014 mm 2 for 250 I¼m droplets and from 0.348 ±0.017 mm 2 to 0.537 ±0.024 mm 2 for 450 I¼m droplets. In addition, their fading times increased from 36 ±7 s to 43 ±6 s at 30% RH and from 53 ±10 s to 62 ±3 s at 60% RH for 250 I¼m droplets, and from 98 ±6 s to 107 ±5 s at 30% RH and from 145 ±5 s to 151 ±8 s at 60% RH for 450 I¼m droplets. In comparison, addition of the petroleum oil surfactant to the herbicide solution reduced the maximal coverage areas and shortened the droplet fading times but increased droplet penetration rates. Therefore, to improve spray coverage area and reduce droplet evaporation, herbicide spray solutions that already contain a surfactant could be amended with the seed oil surfactant. The petroleum oil surfactant could be used when enhancement of droplet penetration into leaf tissues is necessary.

Controlled attenuation parameter is correlated with actual hepatic fat content in patients with non-alcoholic fatty liver disease with none-to-mild obesity and liver fibrosis.

Non-invasive steatosis-quantifying methods are required for non-alcoholic fatty liver disease (NAFLD) patients in order to monitor disease severity and assess therapeutic efficacy. Controlled attenuation parameter (CAP) evaluated with vibration-controlled transient elastography can predict the presence of steatosis, but its application to absolute hepatic fat quantitation remains unclear. The aim of this st\udy was to examine whether CAP is correlated with real hepatic fat content in NAFLD patients. Eighty-two NAFLD patients who had undergone percutaneous liver biopsy were enrolled. CAP was measured using FibroScan(®) just before liver biopsy. The percentage of fat droplet area to hepatocyte area in biopsied specimen was determined morphometrically using computerized optical image analyzing system. The correlation between CAP and liver histology was examined. CAP showed an excellent correlation with actual liver fat percentage in the NAFLD patients with body mass index (BMI) of less than 28kg/m(2) (r = 0.579, P <0.0001), especially less than 25kg/m(2) (r = 0.708, P <0.01), but the meaningful correlation disappeared in the patients with BMI of 28kg/m(2) or more. In the patients with BMI of less than 28kg/m(2) , CAP quantitativeness was affected by the presence of stage 2-4 fibrosis, but not the presence of hepatocyte ballooning and severity of lobular inflammation. CAP may be a promising tool for quantifying hepatic fat content in NAFLD patients with none-to-mild obesity and liver fibrosis. Further improvement of CAP performance is needed for the NAFLD patients with BMI of more than 28kg/m(2) or significant hepatic fibrosis.

Experimental study on water separation process in a novel spray flash vacuum evaporator with heat-pipe

Based on the high heat transfer performance of heat pipe (HP) and large specific surface area of small diameter droplets, HP and spray technologies are combined in a novel single stage vacuum evaporator and artificial seawater with 3% saltness is studied experimentally. Parametric studies are carried out, such as cold source and heat source temperature, spray temperature, and spray flow. The results show that: the maximum heat flux density reaches 32Wcm−2 on evaporator bland plate; HPs absorb energy effectively from low grade heat source (40–80°C) then transfer the energy to the droplets already flashed, so as to maintain or even increase the superheat degree of droplets during evaporating process; This method can significantly improve the water separation rate (quality of condensed water/quality of dilute solution∗100%); Changing the parameters can regulate water separation from 0% to 65%. Thus it has important significance for utilizing lower grade heat source effectively, gaining brine, and promoting the fresh water yield per unit volume and adaptability to variable load in desalination project.

YC-1 induces lipid droplet formation in RAW 264.7 macrophages.

Background3-(5'-Hydroxymethyl-2'-furyl)-1-benzylindazole (YC-1) is a potential anticancer drug that may activate soluble guanylyl cyclase (sGC) and increase the level of cyclic guanosine monophosphate (cGMP). The aim of this study was to explore the effects of YC-1 on lipid droplet accumulation and foam cell formation in macrophages.ResultsHuman-oxidized low density lipoprotein (ox-LDL) was used to induce accumulation of lipid droplets in a murine macrophage cell line, RAW 264.7. Oil red O staining showed that treatment with 20 μM YC-1 for 24 h increased the area of intracellular lipid droplets in macrophages. The results of high content screening (HCS) with the AdipoRed™ assay further revealed that YC-1 enhanced ox-LDL-induced foam cell formation. This was evidenced by an increase in the total area of lipid droplets and the mean fluorescence intensity per cell. Inhibition of cGMP-dependent protein kinase (PKG) using KT5823 significantly reduced YC-1-enhanced lipid droplet formation in ox-LDL-induced macrophage foam cells.ConclusionYC-1 induces lipid droplet formation in macrophages, possibly through the sGC/cGMP/PKG signaling pathway. This chemical should be tested with caution in future clinical trials.

Registration of Times of Preserving the Lowered Temperatures of Combustion Products in The Trace of the Aerosol Flow

This study examines the traces of water droplets moving through high-temperature combustion products (initial temperatures are 430–950 K). The temperature of a gas-vapor mixture in the area of droplets’ traces is measured using low-inertia thermocouples (thermal lag is less than 0.1 s). The experiments revealed that the temperature in the trace of water droplets is significantly reduced (from 15 K to 140 K) even when using an aerosol flow with small droplets. The experiments showed that the times of keeping low temperatures in the trace of water droplets may reach 30 s.

Preparation and Thermal Properties of Fatty Alcohol/Surfactant/Oil/Water Nanoemulsions and Their Cosmetic Applications

Physicochemical properties of oil-in-water (O/W) emulsions containing fatty alcohols and surfactants have been investigated with the aim of developing new formulations that are less viscous and more transparent than conventional milky lotions, as well as for providing greater skin-improving effects. O/W-based creams can be converted to low viscosity milky lotions following their emulsification with a homogenizer at temperatures greater than the transition temperatures of their molecular assemblies (α-gel). The stability of the O/W emulsions evaluated in the current study increased as the transition temperatures of the molecular assemblies formed from their fatty alcohol and surfactant constituents increased. A decrease in the emulsion droplet size led to the formation of a new formulation, which was transparent in appearance and showed a very low viscosity. The absence of a molecular assembly (α-gel) formed by the fatty alcohol and surfactant molecules in the aqueous phase allowed for the formation of a stable transparent and low viscosity nanoemulsion. Furthermore, this decrease in droplet size led to an increase in the interfacial area of the emulsion droplets, with almost all of the fatty alcohol and surfactant molecules being adsorbed on the surfaces of the emulsion droplets. This was found to be important for preparing a stable transparent formulation. Notably, this new formulation exhibited high occlusivity, which was equivalent to that of an ordinary cosmetic milky lotion, and consequently provided high skin hydration. The nanoemulsion was destroyed following its application to the skin, which led to the release of the fatty alcohol and surfactant molecules from the surface of the nanoemulsion into the aqueous phase. These results therefore suggest that the fatty alcohol and surfactant molecules organized the molecular assembly (α-gel) and allowed for the reconstruction of the network structure.

Efavirenz Self-Nano-Emulsifying Drug Delivery System: In Vitro and In Vivo Evaluation.

Self-emulsifying drug delivery system (SEDDS) is the isotropic and thermodynamically stable mixture of oil, surfactant, co-solvent/surfactant, and drug. It emulsifies spontaneously when introduced into an aqueous phase under a mild agitation. The current study was aimed to prepare SNEDDS to augment solubility, release rate, and oral bioavailability of BCS class II drug, efavirenz (EFV). A series of oil, surfactant, and co-surfactant was screened out by a ternary phase diagram to locate a better homogenous mixture. The prepared SNEDDS was evaluated regarding its appearance, mean droplet size, phase separation, in vitro drug release, and oral bioavailability. Among the screened oil, surfactant, and co-surfactant, Labrafil M 2125 CS, Tween 80, and Transcutol®P mixture exhibited superior solubilizing capacity, respectively. Optimized SNEDDS exhibits 98.39% drug release. SNEDDS dissolution behavior was attributed to oil/surfactant ratios and properties of the surfactant phase. It also demonstrates threefold increments in the area under curve (AUC) in comparison to neat EFV. Furthermore, the optimized SNEDDS does not show any vitrification during its 3-month storage. In the present study, better performance of SNEDDS is explained by various factors like (i) improved surface area of droplets, (ii) superior solubilization potential for hydrophobic drugs due to Labrafil M 2125 CS, and (iii) result of surfactant on mucosal permeability. This study demonstrated that SNEDDS may be an alternative approach for the poorly soluble drugs to improve their solubility and oral bioavailability.

Development and validation of a laser-induced breakdown spectroscopic method for ultra-trace determination of Cu, Mn, Cd and Pb metals in aqueous droplets after drying

The present study reports a fast and accurate methodology for laser-induced breakdown spectroscopic, LIBS, analysis of aqueous samples for environmental monitoring purposes. This methodology has two important attributes: one is the use of a 300nm oxide coated silicon wafer substrate (Si+SiO2) for the first time for manual injection of 0.5 microliter aqueous metal solutions, and two is the use of high energy laser pulses focused outside the minimum focus position of a plano convex lens at which relatively large laser beam spot covers the entire droplet area for plasma formation. Optimization of instrumental LIBS parameters like detector delay time, gate width and laser energy has been performed to maximize atomic emission signal of target analytes; Cu, Mn, Cd and Pb. Under the optimal conditions, calibration curves were constructed and enhancements in the LIBS emission signal were obtained compared to the results of similar studies given in the literature. The analytical capability of the LIBS technique in liquid analysis has been improved. Absolute detection limits of 1.3pg Cu, 3.3pg Mn, 79pg Cd and 48pg Pb in 0.5 microliter volume of droplets were obtained from single shot analysis of five sequential droplets. The applicability of the proposed methodology to real water samples was tested on the Certified Reference Material, Trace Metals in Drinking Water, CRM-TMDW and on ICP multi-element standard samples. The accuracy of the method was found at a level of minimum 92% with relative standard deviations of at most 20%. Results suggest that 300nm oxide coated silicon wafer has an excellent potential to be used as a substrate for direct analysis of contaminants in water supplies by LIBS and further research, development and engineering will increase the performance and applicability of the methodology.