• Korean Journal of Soil Science and Fertilizer
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• v.32 no.3
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• pp.274-278
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• 1999

Determination of soil texture, particularly the clay fraction, is an important measurement in most researches related with soil. In this study micro-pipette method For soil particle size analysis was compared with the standard hydrometer method. Micro-pipette method can eliminate the need for bulky laboratory equipment and long settling times associated with the standard hydrometer or pipette method. In the results of this investigation, the particle size data obtained with micro-pipette method were in good agreement with those found using standard hydrometer method. And with this method one person could run analysis much larger numbers of soil sample per day than with hydrometer method in relatively small laboratory space.

• Preventive Nutrition and Food Science
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• v.4 no.2
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• pp.85-87
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• 1999

A simple and rapid method to estimate the viscosity of chitosan using laboratory pipettes was developed. The voscosities of nine different chitosan samples, prepared ini 1 % acetic acid at a 1% concentration , were measured with a standard viscometer. Prior to measurement of flow time of 1% chitosan solution with a pipette, twelve pipettes were assorted into three groups with flow times of 4, 5 and 6 sec after measuring passage of 9 ml of 1% acetic acid througth a 10 ml pipette. With each group of pipettes. flow time of 1% chitosan solution was determined by measuring the delivery time of 5 ml of the 10ml solution through a 10 ml pipette. Results of regression analyses revealed high linear relationship(R2=0.9812, 0.9663, and 0.9754) between viscosities calculated with a viscometer and flow times measured with 4, 5 or 6 sec group pipettes. The viscosity of chitosan could be readily and accurately estimated from these linear regression equation by measuring flow times based on pipette delivery.

• Korean Journal of Environmental Agriculture
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• v.35 no.4
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• pp.263-269
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• 2016

BACKGROUND: The personal protective equipments (PPEs) is the most important factor for reducing the pesticide exposure during the preparation and spraying of pesticides. This study was to investigate the retention, repellence and penetration of protective clothing of PPEs according to the ISO 22608 'Liquid penetration resistance-pipette test. Protective clothing for agriculture worker is very important for their health. However, test method for measurement of protective clothing is not presented in Korea. METHODS AND RESULTS: In order to measure the retention, repellence and penetration of protective clothing, a apparatus for pipette method in accordance with the ISO Guideline was prepared. The test was conducted at $25{\pm}5^{\circ}C$, $60{\pm}10%$ of relative humidity and pipette applied to a apparatus was validated to take exact amount(0.2 mL). The retention, repellence and penetration of five types of protective clothing and one type of shirt were analyzed by GC/MS. Pendimethalin(5% a.i, emulsion) was used as a test pesticide to measure above factors. The retention were less than 11.0% with the exclusion of two types(F4 and shirt) and the repellency was more than 67.0% with the exclusion of shirt material. The penetration was less than 5.4%, however, that of shirt was 66.7%. CONCLUSION: This results indicated that all protective clothing were suitable to use as PPEs according to the criteria specified by ISO Guide 22608. However, shirt was not suitable due to high penetration. This test method established for measurement the retention, repellence and penetration of protective clothing will help to establish the test notice of pipette method.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.6
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• pp.741-748
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• 1997

In the present study, we have investigated the effect of metabolic inhibition on the inward rectifier K current ($I_{K1}$). Using whole cell patch clamp technique we applied voltage ramp from +80 mV to -140 mV at a holding potential of -30 mV and recorded the whole cell current in single ventricular myocytes isolated from the rabbit heart. The current-voltage relationship showed N-shape (a large inward current and little outward current with a negative slope) which is a characteristic of $I_{K1}$. Application of 0.2 mM dinitrophenol (DNP, an uncoupler of oxidative phosphorylation as a tool for chemical hypoxia) to the bathing solution with the pipette solution containing 5 mM ATP, produced a gradual increase of outward current followed by a gradual decrease of inward current with little change in the reversal potential (-80 mV). The increase of outward current was reversed by glibenclamide ($10\;{\mu}M$), suggesting that it is caused by the activation of $K_{ATP}$. When DNP and glibenclamide were applied at the same time or glibenclamide was pretreated, DNP produced same degree of reduction in the magnitude of the inward current. These results show that metabolic inhibition induces not only the increase of $K_{ATP}$ channel but also the decrease of $I_{K1}$. Perfusing the cell with ATP-free pipette solution induced the changes very similar to those observed using DNP. Long exposure of DNP (30 min) or ATP-free pipette solution produced a marked decrease of both inward and outward current with a significant change in the reversal potential. Above results suggest that the decrease of $I_{K1}$ may contribute to the depolarisation of membrane potential during metabolic inhibition.

• Korean Journal of Animal Reproduction
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• v.19 no.3
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• pp.181-189
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• 1995

In this study, methods on fabrication of microtool and setting of micromanipulator were examined and relationship between first polar body extrusion rate and maturation time of follicular oocyte, enulceation rae and repetition of trial, and enucleation rate and maturation period were investigated. The results are as follows: 1. Suitable outside diameter of micropipette tube was 1mm. Holding pipette with less than diameter of oocyte was fitred for manipulation, and zona dissection needle was easily operated when its sharp-point had diameter of about 8 ${\mu}{\textrm}{m}$ and length of 300${\mu}{\textrm}{m}$. The injection pipette with 20~35${\mu}{\textrm}{m}$ outside diameter was adequate for injection of blastomere into perivitelline space. 2. Separation of blastomere was effective when zona pellucida had cut with zonadissection needle and the embryo was pipetted gently with the pipette that had narrower diameter than that of embryo until separation of blastomeres had completed. 3. The extrusion rate of first polar body was 78% during 20~24% hours incubation for maturation. 4. According to repetitions of micromanipulation, the enucleation rate was increased to 85% and the time required for enucleation of a oocyte was shortened to 3 min. 5. The extrusion rate of first polar body and enucleation rate were 82 and 76% respectively, in the group of the oocytes cultured for 22 hours. However in the group cultured for 24 hours, the extrusion rate of first polar body and enucleation rate were 53 and 100% respectively.

• Journal of the Korean Institute of Intelligent Systems
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• v.14 no.4
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• pp.411-417
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• 2004

Recently, instruments and systems related on biological technology have been enormously developed. Particularly, many researches for biological cell injection have been carried out. Usually, excessive contact force occurring when the end-effector and a biological cell contact might make a damage on the cell. Unfortunately, the excessive force could easily destroy the membrane and tissue of the cell. In order to overcome the problem, we proposed a new injection system for biological cell manipulation. The proposed injection system can measure the contact force between a pipette and a cell by using a force sensor. Also, we used vision technology to correctly guide the tip of the pipette to the cell. Consequently, the proposed injection system could safely manipulate the biological cells without any damage. This paper presents the introduction of our new injection system and design concepts of the new micro end-effector. Through a series of experiments the proposed injection system shows the possibility of application for precision biological cell manipulation such as DNA operation.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.5
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• pp.315-320
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• 2006

A precision test of hydrometer method, used to determine soil texture, was conducted on selected 10 soil samples, compared to pipette method. Soil texture measurements with hydrometer method were performed with monitoring the temperature of soil suspension in settling cylinder. The temperature and its fluctuation during settling time had a range of $13^{\circ}C-28^{\circ}C$ and $0.2^{\circ}C-4.4^{\circ}C$, respectively. The difference of clay content between hydrometer and pipette method were distributed from -6.4% to 4.0%. Positive end of difference in clay content was observed at soil having very low clay content, whereas negative end at soil having high organic matter content and exchangeable cations. Except both ends, difference in clay content of soils was less than 3%, and expecially closed to 0% in soils having clay content more than 25%. The difference of sand content were distributed from -1.5% to 4.2%. Similar to clay content, positive end soil was soil sample having lowest sand content.

• The Korean Journal of Physiology and Pharmacology
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• v.8 no.6
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• pp.335-338
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• 2004

There are numerous studies on transepithelial transports in duct cells including $Cl^-$ and/or $HCO_3^-$. However, studies on transepithelial $K^+$ transport of normal duct cells in exocrine glands are scarce. In the present study, we examined the characteristics of $K^+$ currents in single duct cells isolated from guinea pig pancreas, using a whole-cell patch clamp technique. Both $Cl^-$ and $K^+$ conductance were found with KCI rich pipette solutions. When the bath solution was changed to low $Cl^-$, reversal potentials shifted to the negative side, $-75{\pm}4\;mV$, suggesting that this current is dominantly selective to $K^+$. We then characterized this outward rectifying $K^+$ current and examined its $Ca^{2+}$ dependency. The $K^+$ currents were activated by intracellular $Ca^{2+}$. 100 nM or 500 nM $Ca^{2+}$ in pipette significantly (P<0.05) increased outward currents (currents were normalized, $76.8{\pm}7.9\;pA$, n=4 or $107.9{\pm}35.5\;pA$, n=6) at +100 mV membrane potential, compared to those with 0 nM $Ca^{2+}$ in pipette $(27.8{\pm}3.7\;pA,\;n=6)$. We next examined whether this $K^+$ current, recorded with 100 nM $Ca^{2+}$ in pipette, was inhibited by various inhibitors, including $Ba^{2+}$, TEA and iberiotoxin. The currents were inhibited by $40.4{\pm}%$ (n=3), $87.0{\pm}%$ (n=5) and $82.5{\pm}%$ (n=9) by 1 mM $Ba^{2+}$, 5 mM TEA and 100 nM iberiotoxin, respectively. Particularly, an almost complete inhibition of the current by 100 nM iberiotoxin further confirmed that this current was activated by intracellular $Ca^{2+}$. The $K^+$ current may play a role in secretory process, slnce recycling of $K^+$ is critical for the initiation and sustaining of $CI^-$ or $HCO_3^-$ secretion in these cells.

• Proceedings of the Korean Biophysical Society Conference
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• 1997.07a
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• pp.17-17
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• 1997

We investigated the relationship between the voltage-operated calcium channel current and the corresponding [Ca$^{2＋}$]i change (Ca$^{2＋}$-transient) in guinea-pig gastric myocyte. Fluorescence microspectroscopy was combined with conventional whole-cell patch clamp technique and fura-2 (80 $\mu$M) was added into the CsCl-rich pipette solution.(omitted)

• The Korean Journal of Physiology and Pharmacology
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• v.3 no.6
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• pp.547-554
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• 1999

The aim of the present study is to investigate the contribution of $Ca^{2+} ?activated\;K^+\;(K_{Ca})$ channels and delayed rectifier $K^+\;(K_V)$ channels to the resting membrane potential (RMP) in rabbit middle cerebral arterial smooth muscle cells. The RMP and membrane currents were recorded using the whole-cell patch configuration and single $K_{Ca}$ channel was recorded using the outside-out patch configuration. Using the pipette solution containing 0.05 mM EGTA, the RMP was $-25.76{\pm}5.08$ mV (n=12) and showed spontaneous transient hyperpolarizations (STHPs). The membrane currents showed time- and voltage-dependent outward currents with spontaneous transient outward currents (STOCs). When we recorded the membrane potential using the pipette solution containing 10 mM EGTA, the RMP was depolarized and did not show STHPs. The membrane currents showed no STOCs but only showed slowly inactivating outward currents. External TEA (1 mM) reversibly inhibited the STHPs, depolarized the RMP, reduced the membrane currents, abolished STOCs, and decreased the open probability of single $K_{Ca}$ channel. When $K_V$ currents were isolated, the application of 4-AP (5 mM) depolarized the RMP. The important aspect of our results is that $K_{Ca}$ channel is responsible for the generation of the STHPs in the membrane potential and plays an important role in the regulation of the RMP and $K_V$ channel is also responsible for the regulation of the RMP in rabbit middle cerebral arterial smooth muscle cells.