Name: macro-rheology characterization of gill raker mucus in the silver carp, hypophthalmichthys molitrix
Uploaded: 2020-07-10T14:00:00.000+00:00
Duration: 9 min 13 s
Description: Watch this Scientific Journal Video about Macro-Rheology Characterization of Gill Raker Mucus in the Silver Carp, Hypophthalmichthys molitrix at JoVE.com

著者らは、GWバイオミメティクスバイオインスピレーション工学センターからの支援と資金援助を認めている。ジョージ・ワシントン大学生物科学科のL・パトリシア・ヘルナンデス教授は、調査にインスピレーションを与え、継続的なコラボレーションを行い、銀鯉の生理学に関する生物学的専門知識を提供し、粘液サンプルを提供してくれたことに感謝します。私たちは、デビッド・パルンボ氏、カーリー・コーエン氏、アイザック・フィンバーグ氏、ドミニク・ペトロシーノ氏、アレクシス・レンデロス氏、プリシラ・ヴァルゲーゼ氏、カーター・テゲン氏、ラガフ・パイジュル氏の研究室での支援、トーマス・エヴァンス氏とTAインスツルメンツのトーマス・エヴァンス氏とジェームズ・トーマス氏に感謝します。図5A,Cの画像は、ジョージワシントン大学生物科学科のL.パトリシア・ヘルナンデス教授が行った解剖中に撮影されました。

<ol>
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利益相反は宣言されていません。

このプロトコルを開発する主な目的の1つは、非常に小さなサンプル量が利用可能な場合にGR粘液のレオロジー特性に適していることを確立することです。我々は、GR粘液のレオロジー特性を完全に特徴付けるために銀鯉の群れからのより多くのサンプルが必要であり、ここに提示されるデータは銀鯉の集団全体の一般化ではないことを認める。我々の技術は、少量のサンプルのレオロジー特?...

銀の鯉、眼圧性モリトリックスは、プランクチボラスフィルターフィーダーであり、米国のいくつかの自然水路に浸透している侵略的な種です。この種は、最初は藻類の花1、2、3を制御するために、ミシシッピ川の上流域で導入されました。銀の鯉は非常に有効なフィーダーである。通常、その消耗品の粒子サイズは4〜20μmから約80μm3、4、5の大きな動物プランクトンまで及ぶ。この種は他の在来魚と競合しており、利用可能な資源1、2、6を制限することで、ネイティブの水路に甚大な被害を与える可能性があります。したがって、銀の鯉や大きな頭の鯉などの魚を餌にするフィルターは、五大湖1、2、6、7、8に大きな脅威を与えます。
魚の餌付けフィルターは、その表面に存在する粘液の薄い層を持つギルレーカー(RS)と呼ばれる特別な器官を持っています。これらの器官は入ってくる液体からの小さい粒子のろ過および凝集の効率を改善する。本明細書に提示されるプロトコルの目標は、銀の鯉の中のギルレーカーの内面から取得した非ニュートン、剪断間薄化材料特性および降伏応力を特徴付ける。GR粘液の降伏応力の値は、回転式の表現力計を用いて確認され、この研究で注目されている。測定された降伏応力は、「見かけの降伏応力」とも呼ばれ、定常せん断速度や動的振動歪型タイプ9、10などの試験方法に依存します。せん断間化の「降伏応力流体」は、重要な加重応力9,11において固体状から液体様の挙動への移行を受ける。見かけの降伏応力は、流れを開始するために必要な最小せん断応力、または粘液がゲル状の材料から流体状の材料に移行するときに、不可逆的な塑性変形が最初に観察される最小せん断応力です。この挙動は、構造化粘弾性材料で観察することができます。GR粘液のゲル状から流体状の挙動への移行には、食品微粒子を収集する接着的役割と、粒子状の送達および濾過プロセスを支援する輸送車両の役割の2つの機能が必要です。粘液の拡張機能は、疾患耐性および呼吸における拡散障壁の作成、栄養因子の制御放出、毒性成分および排泄の制御放出、摂食および入れ子のための代謝経路の作成、捕食者保護の支援、および移動および推進効率12、13、14を改善する境界層改変を生み出すことである。
単純な流体とは異なり、粘液のような複雑な流体は、流れの条件によって異なる特性を持ち、バルクスケールの物理的挙動を定義するために追加の測定パラメータを必要とします。GR粘液の粘度と降伏応力を監視するために、回転レオメーターを使用してレオロジー測定を行います。回転式の回転計は、流体サンプルに接触する回転ディスクを使用して、安定したまたは振動性のせん断応力または歪みを適用し、その応答を測定します。この装置と技術を使用する背後にある根拠は、この測定器は、密度だけでは定義できない銀の鯉のGR粘液の材料特性を記述するための一連の測定値を提供することができるということです。
粘液は粘弾性材料であり、強制変形に対する機械的反応は、純粋な固体(フックの弾性法則によって支配される)と純粋な液体(ニュートンの粘性法則によって支配される)の間にある15,16である。粘液内に含まれる複雑な高分子ネットワークは、外力や変形に応じて伸縮し、方向を変えることができます。回転式の回転計は、図 1と図 2に示すように、円錐形状とペルチェプレートで構成されます (計測仕様については表1を参照)。本研究の目的は、GR粘液のレオロジー特性を決定するプロトコルを開発することであった。粘度計よりも回転式の回転計の利点は、少量のサンプルを使用して動的測定を行う能力です。この研究におけるGR粘液サンプル容積は約1.4mLであった。一方、粘度計は一定のせん断速度に制限されており、大量のサンプルを必要とします。
粘液のレオロジー特性は、銀の鯉の解剖学内で大きく変化することが期待される。例えば、GR表面に存在する粘液の特性は、エピブランチ器官と異なってもよい。魚の異なる領域における粘液特性の潜在的な変動性を考慮して、獲得したGR粘液サンプルを希釈し、回転リオメーターを用いて3つの濃度の溶液を作成し、試験した。プロトコルを実行した後に報告された粘液の変性に関するデータと結果は、測定技術の有効性を示した。この論文で示す例示的なデータは、銀の鯉の集団全体にわたって一般化されることを意図したものではありません。本明細書に提示されるプロトコルは、他の仮説をテストするために、より大きなサンプルセットにわたる粘液学を調査するために拡張することができる。
本研究の目的は、3つの異なる粘液濃度(400mg/mL、200mg/mLおよび100mg/mL)を有するGR粘液学のレオロジー特性の変動を実証することにある。400mg/mL濃度は、魚グラムから採取した生粘液サンプルを表し、除イオン水(DI)を使用して、生の粘液サンプルを200mg/mLおよび100mg/mL濃度に希釈した。粘液サンプルを希釈することで、濃度の関数としての剪断薄化および明らかな収量応力の評価と、GR粘液が非ニュートン行動に移行する濃度の決定が可能となった。シェーカーは、不均一性によるレオロジーデータの誤差を軽減するために、サンプル内の粘液の大きな塊を分解するために使用されました。
魚を含むほとんどの脊椎動物において、主な粘液形成高分子は、絡み合いや化学的架橋によって水中に膨れ込み、ゲル状物質12、13、17、18、19、20を生成する傾向がある糖タンパク質(ムチン)である。高分子、ゲル形成高分子および高含水率は、粘液13における滑りやすさを反映する。高い高い高分子間相互作用はゲル形成をもたらすが、高分子間相互作用または結合の崩壊のレベルが低いと、高粘度流体21が得られる。
魚を供給するフィルターにおける食品微粒子濾過のプロセスは、接着性およびタック22の可能性を決定する凝集および粘度などのGR粘液関連の特性によって助けられている。粘液ベースの接着の強さは、特定の分子間、静電または疎水性相互作用23に依存する。サンダーソンら24 は、粘液ベースの接着の証拠を発見したブラックフィッシュで懸濁液試験を行った。彼らは、粘膜表面を有する浮遊食品微粒子の接着が続いて、それに作用する指向水流によって粘液と結合した粒子の凝集塊の輸送が続くと述べた。水流から発生するせん断ひずみ速度にさらされた粘液は、食物粒子を消化器官に送り込むのを促進する。内視鏡的手法は、ろ過粒子24を観察するために用いた。
GR粘液のレオロジー検査におけるせん断速度と実用的限界の範囲に関する文献は乏しい。そこで、胃、鼻、子宮頸管および肺粘液、サケの皮膚粘液、ハグフィッシュスライム、および骨関節表面潤滑剤に関するレオロジー研究から指導を求め、その後、レオロジー特性と非ニュートン属性を11、12、25、26、27、28、29、30、31に求めた。最近では、魚の皮膚粘液が移動や推進効率に及ぼす影響を、一定のせん断速度粘度測定を用いて検討されている。シーブリーム、シーバスおよびミーグレに関する皮膚粘液の分析研究(希釈または均質化なし)は、典型的には低い剪断速度14で非ニュートンの挙動を示した。 別の関連研究では、セネガルソールの側側および腹側からの生の皮膚粘液サンプルは、非ニュートン的な挙動を示すことが判明し、32と考えられるすべてのせん断速度で腹側粘液のより高い粘度を示した。ヒドロゲル足場の発達に関する他のレオロジープロトコルおよび一定の剪断速度粘度計を用いた高濃度懸濁液についても文献33,34に報告されている。
本研究では、GR粘液特性を、複雑な生体流体25に対する流動学実験で広く使用されている歪速度制御、回転式流動計を用いて調べた。ニュートン流体の場合、見かけの粘度は一定のままで、せん断速度に依存しない、せん断応力はせん断応力率で線形に変化する(図3A、B)。非ニュートン流体(剪断間薄化流体など)の粘度は、せん断速度依存または変形履歴依存である(図3A、B)。損失係数(G")は、材料が流れる傾向に抵抗する程度を表し、流体粘度を表す(図4)。貯蔵弾性率(G')は、応力によって引き起こされた変形に続いて元の形状を回復する材料の傾向を表し、弾性に相当する(図4)。位相角度(δ)または損失接線値は、G"/G'の逆正接から計算されます。これは、エネルギー損失と貯蔵のバランスを表し、粘弾性材料(δ =フック固体の場合は0°、粘性液体の場合はδ=90°、粘弾性固体の場合はδ <45°、粘弾性液体の場合は45°をδ >)を特徴付けるための一般的なパラメータでもあります(図4)25。構造化流体における見かけの降伏応力(σ y)は、定常状態スイープおよび動的応力歪スイープ10からのレオロジーデータで観察できる状態の変化を表す。外部適用応力が見かけの降伏応力よりも小さい場合、材料は弾性的に変形します。応力が見かけの降伏応力(図3Bで「平均応力」としてマーク)を超えると、材料は弾性から塑性変形に移行し、液体状態35で流れ始める。振動応力(または歪み)条件下での粘液サンプルの貯蔵弾性率(G')と損失率(G")を測定すると、ゲル状から粘弾性性の液体状の挙動に物質状態の変化を定量化します。
貯蔵弾性率(G')、損失率(G")および見かけの粘度(η)に関するデータを監視するために実行されるレオメータ試験の種類をここに説明します。ダイナミック振動試験(歪みスイープと周波数スイープ)は、コーンジオメトリの制御された振動の下でG'とG"を監視しました。動的歪みスイープ試験では、固有の材料応答を監視することによって粘液の線形粘弾性領域(LVR)を決定した(図4)。歪みスイープは、一定の振動周波数と温度での降伏動作を決定するために使用されました。動的周波数スイープテストでは、一定の振幅(ひずみまたは応力)と温度での周波数の増加(変形率)に対する材料の応答を監視しました。ひずみは、動的周波数スイープ試験のために線形粘弾性領域(LVR)で維持された。定常せん断率テストでは、コーンジオメトリの安定した回転下での見かけの粘度(η)を監視しました。GR粘液を段階的な応力ステップを行い、見かけの粘度(η、Pa.s)を、せん断速度(ý,1/s)の変化をモニタリングした。
本論文では、GR粘液を、ある線形粘弾性応答範囲を持つ未知の粘弾性の複雑な構造化材料として扱う。魚の粘液は、L.パトリシア・ヘルナンデス教授(ジョージワシントン大学生物科学科)によってミズーリ川のハートクリークの場所での釣り遠征中に銀の鯉のDRから抽出されました1,2,36. Silver 鯉の口の中にある一連の GRs を図 5Aに示し、図5Bに概略図を示します。切除された GR を図5Cに示します。 銀色の鯉のGRsからの粘液の抽出は、図5D、図5D、Eの図の一例として提示される。すべてのレオメータ試験は、22±0.002°Cの一定の制御温度で行われ、漁場1、2、36で記録された温度。 各粘液サンプルを、その測定結果を3回測定し、平均結果を統計的誤差棒と共に提示した。

<table><tbody><tr><td>&lt;strong&gt;Materials&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Kim Wipes</td><td>VWR</td><td>470224-038</td><td>To clean Sample from plate</td></tr><tr><td>Gloves</td><td>VWR</td><td>89428-750</td><td>To prevent contamination of sample</td></tr><tr><td>Pipette</td><td>VWR</td><td>89079-974</td><td>To transport sample from vial to rheometer</td></tr><tr><td>Pipette Tips</td><td>Thermo Scientific</td><td>72830-042</td><td>To transport sample from vial to rheometer</td></tr><tr><td>Shaker</td><td>VWR</td><td>89032-094</td><td>To homogenously mix sample of mucus</td></tr><tr><td>Vials</td><td>VWR</td><td>66008-710</td><td>Contains measured sample volumes</td></tr><tr><td>Weigh Scale</td><td>Ohaus</td><td>Scout &amp;ndash;SPX Balances</td><td>To weigh mass of mucus samples</td></tr><tr><td>&lt;strong&gt;Chemical Reagents&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>De-Ionized Water (H20)</td><td>-</td><td>-</td><td>Liquid</td></tr><tr><td>Sterile 70% Isopropanol (C3H8O)</td><td>VWR</td><td>89108-162</td><td>Liquid</td></tr><tr><td>&lt;strong&gt;GR Mucus&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>100 mg/mL concentration, 2mL</td><td>-</td><td>-</td><td>Viscoelastic Material</td></tr><tr><td>400 mg/mL concentration, 1mL</td><td>-</td><td>-</td><td>Viscoelastic Material</td></tr><tr><td>200 mg/mL concentration, 1mL</td><td>-</td><td>-</td><td>Viscoelastic Material</td></tr><tr><td>&lt;strong&gt;Software&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>MATLAB</td><td>Mathworks</td><td>R2017a</td><td>Data analysis, post-processing and graphical representation</td></tr><tr><td>Trios</td><td>TA Instruments</td><td>v4.5.042498</td><td>Rheometer instrument control and analysis software</td></tr></tbody></table>

macro-rheology characterization of gill raker mucus in the silver carp, hypophthalmichthys molitrix

銀の鯉 、眼圧動性モリトリクスは、その非常に効率的なフィルター供給機構のために、ミシシッピ川の上流域の自然の水路がはびこる侵襲的なプランクチボラスフィルターフィーダー魚です。ギルレーカー(DR)と呼ばれる特徴的な器官は、多くのそのようなフィルターフィーダーに見られる、数ミクロンの大きさの植物プランクトンのような食品粒子の効率的なろ過を促進する。
GR粘液のレオロジーを調査する動機は、銀の鯉のフィルター供給プロセスを支援する役割を理解したいという私たちの願望に由来します。粘液が豊富な流体は、「厚くて粘着性のある」状態で、食品微粒子の付着を促進し得る。GR膜を通る浸透および輸送は、様々なせん断歪速度を誘発する外部せん断力の作用によって促進される。したがって、粘液の手引きは、魚を供給するフィルターのプール内の銀の鯉の驚異的な競争の性質に重要な手がかりを提供することができます。これに基づいて、GR粘液は、食品粒子に接着機能を提供し、フィルター供給プロセスを支援する輸送手段として作用し得ることを示唆した。
プロトコルの主な目的は、粘液の降伏応力を決定することです, 不可逆塑性変形が構造化された粘弾性材料を介して最初に観察される流れを開始するために必要な最小せん断応力に起因します.従って、GR粘液のレオロジー特性、すなわち、粘度、貯蔵、および損失モジュライは、回転レオメータを用いてその非ニュートン、剪断薄膜性について調べた。
ここで提示されたプロトコルは、ミズーリ川のハートクリークの場所で釣られた銀鯉のギルレーカーから抽出された粘液のレオロジー特性を分析するために使用されます。このプロトコルは、構造粘弾性材料と想定される粘液のレオロジー試験および物質的特性化のための効果的な戦略を開発することを目的としています。

このセクションでは、円錐形状(直径40mm、1°0'11')とペルチェプレートを持つ回転式流圧計を用いたGR粘液の実験結果を紹介します。実験は、GR粘液の非ニュートン、せん断間の挙動と、ゲル状物質から流体状の材料への粘液の移行を表す明らかな収量応力を特徴付けるのに役立った。代表的な結果は、低トルク限界と回転式流量計の二次流れ効果の定量的記述を伴う。計測限界と定常および動?...

Watch this Scientific Journal Video about Macro-Rheology Characterization of Gill Raker Mucus in the Silver Carp, Hypophthalmichthys molitrix at JoVE.com

Macro-Rheology Characterization of Gill Raker Mucus in the Silver Carp, Hypophthalmichthys molitrix

このプロトコルは、銀の鯉のギルレーカー(の)上に存在する粘液のレガロジー特性を実行する方法を提示します。粘度、保存および損失モジュライを測定して得られるGR粘液の粘弾性特性は、見かけの収量応力について評価され、GRにおけるフィルタ供給機構を理解する。

銀の鯉、眼圧軟化モリクスにおけるギル・レイカー粘液のマクロ・レオロジー特性

The silver carp, Hypophthalmichthys molitrix, is an invasive planktivorous filter feeder fish that infested the natural waterways of the upper Mississippi ...

macro-rheology-characterization-gill-raker-mucus-silver-carp

Research

JoVE Journal

Engineering

Macro-Rheology Characterization of Gill Raker Mucus in the Silver Carp, Hypophthalmichthys molitrix

3.0K ビュー.  The George Washington University. このプロトコルは、銀の鯉のギルレーカー(の)上に存在する粘液のレガロジー特性を実行する方法を提示します。粘度、保存および損失モジュライを測定して得られるGR粘液の粘弾性特性は、見かけの収量応力について評価され、GRにおけるフィルタ供給機構を理解する。

ビデオ: Macro-Rheology Characterization of Gill Raker Mucus in the Silver Carp, Hypophthalmichthys molitrix

A Time Differential Staining Technique Coupled with Full Bilateral Gill Denervation to Study Ionocytes in Fish

Branchial ionocytes (ICs) are the functional units for ionic regulation in fish. In adults, they are found on the filamental and lamellar epithelia of the gill where they transport ions such as Na+, Cl- and Ca2+ via a variety of ion channels, pumps and exchangers. The teleost gill is extrinsically innervated by the facial (VI), glossopharyngeal (IX) and vagus (X) nerves. The IX and X nerves are also the extrinsic source of branchial IC innervation. Here, two techniques used to study the innervation, proliferation and distribution of ICs are described: a time differential staining technique and a full bilateral gill denervation technique. Briefly, goldfish are exposed to a vital mitochondrion-specific dye (e.g., MitoTracker Red) which labels (red fluorescence) pre-existing ICs. Fish were either allowed to recover for 3 - 5 days or immediately underwent a full bilateral gill denervation. After 3 - 5 days of recovery, the gills are harvested and fixed for immunohistochemistry. The tissue is then stained with an &#945;-5 primary antibody (targets Na+/K+ ATPase containing cells) in conjunction with a secondary antibody that labels all (both new and pre-existing) ICs green. Using confocal imaging, it was demonstrated that pre-existing ICs appear yellow (labelled with both a viable mitochondrion-specific dye and &#945;-5) and new ICs appear green (labelled with &#945;-5 only). Both techniques used in tandem can be applied to study the innervation, proliferation and distribution of ICs on the gill filament when fish are exposed to environmental challenges.

This manuscript describes a protocol to track the re-distribution of branchial ionocytes and their innervation using a time differential staining technique coupled with full bilateral gill denervation.

魚にIonocytesを研究するために完全な二国間ギル脱神経と相まって時差染色技術

Branchial ionocytes (ICs) are the functional units for ionic regulation in fish. In adults, they are found on the filamental and lamellar epithelia of the ...

発生生物学

VacuSIP, an Improved InEx Method for In Situ Measurement of Particulate and Dissolved Compounds Processed by Active Suspension Feeders

Benthic suspension feeders play essential roles in the functioning of marine ecosystems. By filtering large volumes of water, removing plankton and detritus, and excreting particulate and dissolved compounds, they serve as important agents for benthic-pelagic coupling. Accurately measuring the compounds removed and excreted by suspension feeders (such as sponges, ascidians, polychaetes, bivalves) is crucial for the study of their physiology, metabolism, and feeding ecology, and is fundamental to determine the ecological relevance of the nutrient fluxes mediated by these organisms. However, the assessment of the rate by which suspension feeders process particulate and dissolved compounds in nature is restricted by the limitations of the currently available methodologies. Our goal was to develop a simple, reliable, and non-intrusive method that would allow clean and controlled water sampling from a specific point, such as the excurrent aperture of benthic suspension feeders, in situ. Our method allows simultaneous sampling of inhaled and exhaled water of the studied organism by using minute tubes installed on a custom-built manipulator device and carefully positioned inside the exhalant orifice of the sampled organism. Piercing a septum on the collecting vessel with a syringe needle attached to the distal end of each tube allows the external pressure to slowly force the sampled water into the vessel through the sampling tube. The slow and controlled sampling rate allows integrating the inherent patchiness in the water while ensuring contamination free sampling. We provide recommendations for the most suitable filtering devices, collection vessel, and storing procedures for the analyses of different particulate and dissolved compounds. The VacuSIP system offers a reliable method for the quantification of undisturbed suspension feeder metabolism in natural conditions that is cheap and easy to learn and apply to assess the physiology and functional role of filter feeders in different ecosystems.

VacuSIP, an Improved InEx Method for In Situ Measurement of Particulate and Dissolved Compounds Processed by Active Suspension Feeders

We introduce the VacuSIP, a simple, non-intrusive, and reliable method for clean and accurate point sampling of water. The system was developed and evaluated for the simultaneous collection of the water inhaled and exhaled by benthic suspension feeders in situ, to cleanly measure removal and excretion of particulate and dissolved compounds.

VacuSIP、のための改良INEX方法<em&gt;その場で</em&gt;微粒子と溶解した化合物の測定は、アクティブサスペンションフィーダによって処理します

Benthic suspension feeders play essential roles in the functioning of marine ecosystems. By filtering large volumes of water, removing plankton and ...

環境学

Salinity-dependent Toxicity Assay of Silver Nanocolloids Using Medaka Eggs

Salinity is an important characteristic of the aquatic environment. For aquatic organisms it defines the habitats of freshwater, brackish water, and seawater. Tests of the toxicity of chemicals and assessments of their ecological risks to aquatic organisms are frequently performed in freshwater, but the toxicity of chemicals to aquatic organisms depends on pH, temperature, and salinity. There is no method, however, for testing the salinity dependence of toxicity to aquatic organisms. Here, we used medaka (Oryzias latipes) because they can adapt to freshwater, brackish water, and seawater. Different concentrations of embryo-rearing medium (ERM) (1x, 5x, 10x, 15x, 20x, and 30x) were employed to test the toxicity of silver nanocolloidal particles (SNCs) to medaka eggs (1x ERM and 30x ERM have osmotic pressures equivalent to freshwater and seawater, respectively). In six-well plastic plates, 15 medaka eggs in triplicate were exposed to SNCs at 10 mg/L&#8722;1 in different concentrations of ERM at pH 7 and 25 &#176;C in the dark.
We used a dissecting microscope and a micrometer to measure heart rate per 15 sec and eye diameter on day 6 and full body length of the larvae on hatching day (section 4). The embryos were observed until hatching or day 14; we then counted the hatching rate every day for 14 days (section 4). To see silver accumulation in embryos, we used inductively coupled plasma mass spectrometry to measure the silver concentration of test solutions (section 5) and dechorionated embryos (section 6).The toxicity of the SNCs to medaka embryos obviously increased with increasing salinity. This new method allows us to test the toxicity of chemicals in different salinities.

Embryonic stages are the most susceptible to xenobiotics. Although chemical toxicity depends on salinity, no method exists to test the salinity dependence of toxicity to aquatic organisms. Here, we describe a new and high-throughput method for determining the salinity dependence of toxicity to aquatic embryos.

メダカの卵を使用したシルバーナノコロイドの塩分依存毒性アッセイ

Salinity is an important characteristic of the aquatic environment. For aquatic organisms it defines the habitats of freshwater, brackish water, and ...

Challenges in Rheological Characterization of Highly Concentrated Suspensions &#8212; A Case Study for Screen-printing Silver Pastes

A comprehensive rheological characterization of highly concentrated suspensions or pastes is mandatory for a targeted product development meeting the manifold requirements during processing and application of such complex fluids. In this investigation, measuring protocols for a conclusive assessment of different process relevant rheological parameters have been evaluated. This includes the determination of yield stress, viscosity, wall slip velocity, structural recovery after large deformation and elongation at break as well as tensile force during filament stretching.
The importance of concomitant video recordings during parallel-plate rotational rheometry for a significant determination of rheological quantities is demonstrated. The deformation profile and flow field at the sample edge can be determined using appropriate markers. Thus, measurement parameter settings and plate roughness values can be identified for which yield stress and viscosity measurements are possible. Slip velocity can be measured directly and measuring conditions at which plug flow, shear banding or sample spillover occur can be identified clearly. 
Video recordings further confirm that the change in shear moduli observed during three stage oscillatory shear tests with small deformation amplitude in stage I and III but large oscillation amplitude in stage II can be directly attributed to structural break down and recovery. For the pastes investigated here, the degree of irreversible, shear-induced structural change increases with increasing deformation amplitude in stage II until a saturation is reached at deformations corresponding to the crossover of G' and G'', but the irreversible damage is independent of the duration of large amplitude shear. 
A capillary breakup elongational rheometer and a tensile tester have been used to characterize deformation and breakup behavior of highly filled pastes in uniaxial elongation. Significant differences were observed in all experiments described above for two commercial screen-printing silver pastes used for front side metallization of Si-solar cells.

A protocol for a robust and application relevant rheological characterization of highly concentrated suspensions is presented. Silver pastes used for screen-printing application in solar cell production are employed as model systems.

高度に濃縮された懸濁液のレオロジー特性評価における課題 - スクリーン印刷シルバーペーストのためのケーススタディ

A comprehensive rheological characterization of highly concentrated suspensions or pastes is mandatory for a targeted product development meeting the ...

工学

Characterization Of Multi-layered Fish Scales (Atractosteus spatula) Using Nanoindentation, X-ray CT, FTIR, and SEM

The hierarchical architecture of protective biological materials such as mineralized fish scales, gastropod shells, ram&#8217;s horn, antlers, and turtle shells provides unique design principles with potentials for guiding the design of protective materials and systems in the future. Understanding the structure-property relationships for these material systems at the microscale and nanoscale where failure initiates is essential. Currently, experimental techniques such as nanoindentation, X-ray CT, and SEM provide researchers with a way to correlate the mechanical behavior with hierarchical microstructures of these material systems1-6. However, a well-defined standard procedure for specimen preparation of mineralized biomaterials is not currently available. In this study, the methods for probing spatially correlated chemical, structural, and mechanical properties of the multilayered scale of A. spatula using nanoindentation, FTIR, SEM, with energy-dispersive X-ray (EDX) microanalysis, and X-ray CT are presented.

Characterization Of Multi-layered Fish Scales Atractosteus spatula Using Nanoindentation, X-ray CT, FTIR, and SEM

This paper presents the methods used for probing spatially correlated chemical, structural, and mechanical properties of the multilayered scale of Atractosteus spatula (A. spatula) using nanoindentation, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and X-ray computed tomography (X-ray CT). The experimental results have been used to investigate the design principles of protective biological materials.

多層魚の鱗の特性（<em&gt; Atractosteusヘラ</em&gt;）ナノインデンテーション、X線CT、FTIR、およびSEMを用いて

The hierarchical architecture of protective biological materials such as mineralized fish scales, gastropod shells, ram&#8217;s horn, antlers, and turtle ...

生物工学

Modeling the Size Spectrum for Macroinvertebrates and Fishes in Stream Ecosystems

The size spectrum is an inverse, allometric scaling relationship between average body mass (M) and the density (D) of individuals within an ecological community or food web. Importantly, the size spectrum assumes that individual size, rather than species&#8217; behavioral or life history characteristics, is the primary determinant of abundance within an ecosystem. Thus, unlike traditional allometric relationships that focus on species-level data (e.g., mean species&#8217; body size vs. population density), size spectra analyses are &#8216;ataxic&#8217; &#8211; individual specimens are identified only by their size, without consideration of taxonomic identity. Size spectra models are efficient representations of traditional, complex food webs and can be used in descriptive as well as predictive contexts (e.g., predicting responses of large consumers to changes in basal resources). Empirical studies from diverse aquatic ecosystems have also reported moderate to high levels of similarity in size spectra slopes, suggesting that common processes may regulate the abundances of small and large organisms in very different settings. This is a protocol to model the community-level size spectrum in wadable streams. The protocol consists of three main steps. First, collect quantitative benthic fish and invertebrate samples that can be used to estimate local densities. Second, standardize the fish and invertebrate data by converting all individuals to ataxic units (i.e., individuals identified by size, irrespective of taxonomic identity), and summing individuals within log2 size bins. Third, use linear regression to model the relationship between ataxic M and D estimates. Detailed instructions are provided herein to complete each of these steps, including custom software to facilitate D estimation and size spectra modeling.

This is a protocol to model the size spectrum (scaling relationship between individual mass and population density) for combined fish and invertebrate data from wadable streams and rivers. Methods include: field techniques to collect quantitative fish and invertebrate samples; lab methods to standardize the field data; and statistical data analysis.

河川生態系におけるマクロ無脊椎動物と魚類のサイズスペクトルのモデリング

The size spectrum is an inverse, allometric scaling relationship between average body mass (M) and the density (D) of individuals within an ecological ...

Combining Microfluidics and Microrheology to Determine Rheological Properties of Soft Matter during Repeated Phase Transitions

The microstructure of soft matter directly impacts macroscopic rheological properties and can be changed by factors including colloidal rearrangement during previous phase changes and applied shear. To determine the extent of these changes, we have developed a microfluidic device that enables repeated phase transitions induced by exchange of the surrounding fluid and microrheological characterization while limiting shear on the sample. This technique is &#181;2rheology, the combination of microfluidics and microrheology. The microfluidic device is a two-layer design with symmetric inlet streams entering a sample chamber that traps the gel sample in place during fluid exchange. Suction can be applied far away from the sample chamber to pull fluids into the sample chamber. Material rheological properties are characterized using multiple particle tracking microrheology (MPT). In MPT, fluorescent probe particles are embedded into the material and the Brownian motion of the probes is recorded using video microscopy. The movement of the particles is tracked and the mean-squared displacement (MSD) is calculated. The MSD is related to macroscopic rheological properties, using the Generalized Stokes-Einstein Relation. The phase of the material is identified by comparison to the critical relaxation exponent, determined using time-cure superposition. Measurements of a fibrous colloidal gel illustrate the utility of the technique. This gel has a delicate structure that can be irreversibly changed when shear is applied. &#181;2rheology data shows that the material repeatedly equilibrates to the same rheological properties after each phase transition, indicating that phase transitions do not play a role in microstructural changes. To determine the role of shear, samples can be sheared prior to injection into our microfluidic device. &#181;2rheology is a widely applicable technique for the characterization of soft matter enabling the determination of rheological properties of delicate microstructures in a single sample during phase transitions in response to repeated changes in the surrounding environmental conditions.

We demonstrate the fabrication and use of a microfluidic device that enables multiple particle tracking microrheology measurements to study the rheological effects of repeated phase transitions on soft matter.

繰り返し相転移の間に柔らかい物質のレオロジー的性質を決定するためのマイクロ流体システムとレオロジーを組み合わせること

The microstructure of soft matter directly impacts macroscopic rheological properties and can be changed by factors including colloidal rearrangement ...

Automatic Image Processing to Determine the Community Size Structure of Riverine Macroinvertebrates

Body size is an important functional trait that can be used as a bioindicator to assess the impacts of perturbations in natural communities. Community size structure responds to biotic and abiotic gradients, including anthropogenic perturbations across taxa and ecosystems. However, the manual measurement of small-bodied organisms such as benthic macroinvertebrates (e.g., &gt;500 &#181;m to a few centimeters long) is time-consuming. To expedite the estimation of community size structure, here, we developed a protocol to semi-automatically measure the individual body size of preserved river macroinvertebrates, which are one of the most commonly used bioindicators for assessing the ecological status of freshwater ecosystems. This protocol is adapted from an existing methodology developed to scan marine mesozooplankton with a scanning system designed for water samples. The protocol consists of three main steps: (1) scanning subsamples (fine and coarse sample size fractions) of river macroinvertebrates and processing the digitized images to individualize each detected object in each image; (2) creating, evaluating, and validating a learning set through artificial intelligence to semi-automatically separate the individual images of macroinvertebrates from detritus and artifacts in the scanned samples; and (3) depicting the size structure of the macroinvertebrate communities. In addition to the protocol, this work includes the calibration results and enumerates several challenges and recommendations to adapt the procedure to macroinvertebrate samples and to consider for further improvements. Overall, the results support the use of the presented scanning system for the automatic body size measurement of river macroinvertebrates and suggest that the depiction of their size spectrum is a valuable tool for the rapid bioassessment of freshwater ecosystems.

The article is based on the creation of an adapted protocol to scan, detect, sort, and identify digitized objects corresponding to benthic river macroinvertebrates using a semi-automatic imaging procedure. This procedure allows the acquisition of the individual size distributions and size metrics of a macroinvertebrate community in about 1 h.

河川大型無脊椎動物の群集サイズ構造を決定するための自動画像処理

Body size is an important functional trait that can be used as a bioindicator to assess the impacts of perturbations in natural communities. Community ...

Rapid Viscoelastic Characterization of Airway Mucus Using a Benchtop Rheometer

In muco-obstructive lung diseases (e.g., asthma, chronic obstructive pulmonary disease, cystic fibrosis) and other respiratory conditions (e.g., viral/bacterial infections), mucus biophysical properties are altered by goblet cell hypersecretion, airway dehydration, oxidative stress, and the presence of extracellular DNA. Previous studies showed that sputum viscoelasticity correlated with pulmonary function and that treatments affecting sputum rheology (e.g., mucolytics) can result in remarkable clinical benefits. In general, rheological measurements of non-Newtonian fluids employ elaborate, time-consuming approaches (e.g., parallel/cone-plate rheometers and/or microbead particle tracking) that require extensive training to perform the assay and interpret the data. This study tested the reliability, reproducibility, and sensitivity of Rheomuco, a user-friendly benchtop device that is designed to perform rapid measurements using dynamic oscillation with a shear-strain sweep to provide linear viscoelastic moduli (G&#39;, G&#34;, G*, and tan &#948;) and gel point characteristics (&#947;c&#160;and &#963;c) for clinical samples within 5 min. Device performance was validated using different concentrations of a mucus simulant, 8 MDa polyethylene oxide (PEO), and against traditional bulk rheology measurements. A clinical isolate harvested from an intubated patient with status asthmaticus (SA) was then assessed in triplicate measurements and the coefficient of variation between measurements is &#60;10%. Ex vivo use of a potent mucus reducing agent, TCEP, on SA mucus resulted in a five-fold decrease in elastic modulus and a change toward a more &#34;liquid-like&#34; behavior overall (e.g., higher tan &#948;). Together, these results demonstrate that the tested benchtop rheometer can make reliable measures of mucus viscoelasticity in clinical and research settings. In summary, the described protocol could be used to explore the effects of mucoactive drugs (e.g., rhDNase, N-acetyl cysteine) onsite to adapt treatment on a case-by-case basis, or in preclinical studies of novel compounds.

The viscoelastic properties of mucus play a critical role in mucociliary clearance. However, traditional mucus rheological techniques require complex and time-consuming approaches. This study provides a detailed protocol for the use of a benchtop rheometer that can rapidly and reliably perform viscoelastic measurements.

ベンチトップレオメーターを使用した気道粘液の迅速な粘弾性特性評価

In muco-obstructive lung diseases (e.g., asthma, chronic obstructive pulmonary disease, cystic fibrosis) and other respiratory conditions (e.g., ...

医学

Standardizing a Non-Lethal Method for Characterizing the Reproductive Status and Larval Development of Freshwater Mussels (Bivalvia: Unionida)

Actively monitoring the timing, development, and reproductive patterns of endangered species is critical when managing for population recovery. Freshwater mussels are among the most imperiled organisms in the world, but information about early larval (glochidial) development and brooding periods is still lacking for many species. Previous studies have focused on the complex life history stage when female mussels are ready to parasitize host fish, but few studies have focused on the brooding period and timing of larval development. The protocol described here allows researchers to non-lethally evaluate the state of gravidity for female mussels. The results of this study show that this method does not affect a female mussel&rsquo;s ability to stay gravid or become gravid again after sampling has been performed. The advantage of this method may permit its use on federally threatened or endangered species or other populations of high conservation concern. This protocol can be adapted for use on both preserved or live individuals and was tested on a variety of mussel species. The database provided is a repository for a breadth of information on timing of reproductive habits and will facilitate future freshwater mussel research, conservation, and recovery efforts.

Standardizing a Non-Lethal Method for Characterizing the Reproductive Status and Larval Development of Freshwater Mussels Bivalvia: Unionida

Freshwater mussel conservation is dependent on monitoring reproductive patterns and processes of species. This study standardizes a non-lethal protocol for sampling gill contents, characterizing larval development, and providing a digital repository for data collected. This protocol-database package will be an important tool for mussel researchers in recovery of imperiled species.

淡水ムール貝の生殖状態と幼虫発達を特徴付けるための非致死的方法の標準化(ビバルビア:ユニオンダ)

Actively monitoring the timing, development, and reproductive patterns of endangered species is critical when managing for population recovery. Freshwater ...

銀の鯉、眼圧軟化モリクスにおけるギル・レイカー粘液のマクロ・レオロジー特性

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